EE-9 M4 APFSDS Testbed. Illustrations by Godzilla funded by our Patreon Campaign.
Federative Republic of Brazil (1985)
Wheeled Reconnaissance Vehicle – 1 Built
In 1984, Engesa initiated the development of an APFSDS (Armor Piercing Fin Stabilized Discarding Sabot) round for the low pressure 90 mm gun of the EE-9. Why exactly Engesa entered such an endeavor is unknown, as kinetic energy projectiles are usually not viable for low pressure guns. Nevertheless, the round was developed and would offer a wider range of ammunition for their customers and make it look like the EE-9, now reaching 10 years of service, was still keeping up with modern developments of its time.
Developing an APFSDS round did not come without its challenges, however. Issues like the muzzle brake, a rifled barrel, materials and manufacturing processes had to be resolved. The culmination of the project seems to have taken place in July 1985, when an EE-9 fitted with a pepperpot-type muzzle brake was presented to an Iraqi delegation. This may suggest an Iraqi influence or interest in the APFSDS round, but sadly, the Iraqis did not end up acquiring the APFSDS round and the project was, for all intents and purposes, abandoned.
The EE-9 M4 APFSDS Testbed.
Source: Claudio Agostini
The EE-9 and Iraq
The story of why the EE-9 Cascavel (English: Rattlesnake) was developed can be traced back to the Second World War. Brazil sent an expeditionary force, known as the ‘Smoking Snakes’, to fight in Italy alongside the Allies. During the Italian campaign, the Brazilian forces were equipped with the 6-wheeled M8 Greyhound armored car. The Greyhound turned into a beloved vehicle for the Brazilian soldiers for its armor, simplicity and mobility, and after WW2, this love would remain embedded in the Brazilian Army.
Although Brazil enjoyed its diplomatic relations with the United States well into the 1970s, the first steps to break free from the United States, from an army materiel point of view, started in 1967. The United States had become increasingly involved with the Vietnam War and, as a result, could not supply Brazil with the cheap equipment it once did. As such, it was decided that the Brazilian Army would instead try to develop their own armored vehicles.
One of these was the EE-9 Cascavel, which was passed on to Engesa for production after the Army had developed a number of prototypes. The EE-9 was a 6 x 6 wheeled vehicle initially armed with a 37 mm, but would be armed with a 90 mm on suggestion of the Portuguese. While being the spiritual successor of the M8 Greyhound, two of the main innovations of the EE-9 were the usage of the boomerang suspension, which enabled it to cross much more difficult terrain ,and the incorporation of bimetallic armor, which offered improved protection over homogenous steel. Engesa managed to secure an export deal with Libya for 200 EE-9s in 1974 and, soon after, would receive an order for an additional 200 vehicles. From there, the EE-9 became Engesa’s flagship product, as they would sell it to multiple South American countries as well.
The use of the EE-9 Cascavel by Libya and its export success managed to get the attention of Iraq. After three weeks of negotiations, Engesa managed to secure the export contract for 364 EE-9s and 148 EE-11s on May 5th 1978. Iraq would be the first to receive a new model of EE-9, known as the EE-9 M4. In contrast to previous models, the EE-9 M4 used an MT-643 transmission which could handle the more powerful Detroit Diesel 6V53 212 hp engine. In addition, the hull featured a number of redesigns, like the integration of the headlights in the lower hull plate instead of the installation on top of the upper front plate. The most significant change was the redesigned ET-90 turret, known as ET-90 II, which was able to incorporate night vision sights.
Iraqi EE-9 M4s lined up.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
A New Generation of Ammunition
Engesa was known for developing a wide range of concepts or options to market to potential customers. Some of these developments were fairly reasonable, while others just seem to have been developed for the sake of making a product and perhaps even the company looking more impressive. The EE-11 Urutu, effectively an EE-9 turned into an armored personnel carrier, was the prime subject for receiving all kinds of variants which tended to not generate any sales, but were extremely simple and cheap to manufacture nonetheless.
The development of the new EE-9 APFSDS (Armor Piercing Fin Stabilized Discarding Sabot) and canister (a round filled with steel balls) rounds may have been such a project according to an ex-Engesa employee, but could also have had some Iraqi influence as well. In 1984, the Engesa subsidiary Engequímica was founded, which was tasked with both the manufacture of all Engesa’s ammunition and the development of the new generation of EE-9 ammunition. The writer will refer to Engequímica for the development side of the ammunition while for the marketing and overarching business side the writer will refer to Engesa instead.
The Engequímica factory.
Source: Engesa Brochure
Considering the EE-9 was still very much the flagship product of Engesa, it is quite likely the company decided to make the gun seem more modern and appealing by offering an APFSDS round. While APFSDS was not a new concept, it had started to generate much more interest by the late 1970s, with NATO countries shifting from APDS (Armor Piercing Discarding Sabot) to APFSDS for both their 105 mm and 120 mm armament. The French also developed a wide range of APFSDS rounds for their high pressure 90 mm F4 guns, which would be mounted on the Brazilian Tamoyo 1 tank, and even some gun-mortars. At the time, Bernardini had also started to take steps by copying and subsequently manufacturing the French APFSDS round of the 90 mm F4 for the Tamoyo program.
The Tamoyo 1.
Source: Author’s collection
Additionally, the Iraqi Army was thought to have requested the development of a canister round for the EE-9 Cascavel somewhere in 1984, as it was embroiled in the Iran-Iraq war at the time. At a similar time, General Amer Rashid had also requested the development of an anti-air EE-9 and it could be that he requested the development of the new ammunition as well. Why exactly the Iraqis sought a canister round for the EE-9 is unknown. It was likely that the canister round was requested to make the EE-9 better equipped against dealing with infantry formations. The Engequímica team developing the round called it the Cartucheira Gigante or Giant Cartridge in English. When the round was fired, it could sweep everything in a cone of about 20 meters (22 yards) wide at a distance 100 meters (109 yards) away, basically functioning like a giant shotgun. In the end, both the APFSDS and canister rounds were presented to an Iraqi delegation.
The canister round weighed 6.2 kg in total and was filled with 1,400 steel balls. Each ball had a diameter of 6 mm (0.25 inch) and weighed 0.88 grams for a total of 1.23 kg of balls inside the round. The effective range of the round was said to have been 150 to 200 meters (164 to 219 yards) and the muzzle velocity was around 520 m/s. Interestingly, Iraq supposedly also requested for the development of a longer range shrapnel round, which seems to appear in an Engesa brochure. Here, the shrapnel round had a muzzle velocity of 600 m/s and an effective range of 700 meters (765 yards). The maximum range was 800 meters (875 yards) with a dispersion of 1 mil (1 meter at 1,000 meters). In contrast to the canister round, which would function like a shotgun, the shrapnel round would detonate at a certain range and act like a large grenade.
The EC-90 Gun
Initially in 1974, Engesa sold the EE-9 Cascavel with the H-90 turret and the 90 mm D921 gun from the French, which was initially used on the AML-90. While preferring to only acquire the guns, the French only sold the gun and turret in a single package. As such, Bolivia, Chile and Libya received the French package. This was fairly advantageous for Engesa, as the AML-90 was widely available to their customer base and crews would need little retraining to serve in an EE-9.
As 284 EE-9s with the French turret were sold, the French caught on to the competitive challenge the vehicle could have on their own export market. As a result, the French raised the turret prices to such an amount that Engesa had no choice but to look for a different option. They found their solution with the Belgian company Cockerill and the EC-90 gun.
Libyan EE-9 M2s with the French turret.
Source: Engesa EE-9 Cascavel 40 anos de combates 1977-2017
The EC-90 90 mm gun was a license production from the Cockerill Mk.3. Engesa acquired the license to produce the low-pressure 90 mm Cockerill 90 Mk. 3 gun in 1975 for US$3 million (US$15.5 million in 2021). The gun would be designated EC-90 by Engesa, with the E standing for Engesa, C for Canhão (Cannon), and 90 for the 90 mm gun. This license deal not only made it possible for Engesa to manufacture their own guns, but it also opened the door for them to design their own turrets. Additionally, due to the incorporation of the bimetallic steel armor, these turrets were also better protected than the French counterparts.
Low Pressure APFSDS?
Developing an APFSDS round for the EC-90 gun did come with a number of issues -the biggest being the very nature of the gun. The EC-90 was a so-called low pressure gun. This meant that the gun used low muzzle velocities which allowed larger caliber guns to be installed on extremely light platforms, such as the 5.5 tonne AML-90 or even a Toyota Technical. The use of low muzzle velocities entailed that traditional kinetic energy (K.E.) based anti-tank rounds, like AP and APDS, became unfeasible, as they relied on high muzzle velocities and thus high pressures for penetration performance.
This issue was circumvented by the usage of chemical energy (C.E.) ammunition, known as HEAT (High Explosive anti-Tank) and HESH (High Explosive Squash Head) ammunition. Chemical energy ammunition takes its penetration performance from the chemical charges inside the ammunition. As such, chemical energy ammunition performance was mostly bound by gun diameter rather than muzzle velocity. This meant that a HEAT round would have the same penetration at point blank as at 1,000 meters (1094 yards), as the potential penetration energy stored inside the round remained the same. Higher muzzle velocities mainly had influence on the accuracy and maximum effective range of the HEAT rounds.
This made low velocity 90 mm guns extremely dangerous, as the HEAT round of the French D921 could penetrate around 320 mm (12.6 inches) of flat steel armor at any range, while the Cockerill and EC-90 could penetrate around 250 mm (10 inches) of flat steel armor at any range as well. The difference in performance had to do with the French expertise in the development of HEAT ammunition. In just a few years, light reconnaissance platforms which previously were lightly armed and posed little threat to main battle tanks could theoretically destroy tanks like the T-55 family and the M48 Patton, even when engaging them frontally.
With the introduction of APFSDS, this performance gap between kinetic and chemical energy ammunition on low pressure guns became more equal. As APFSDS did not require spin stabilization, both the Length to Diameter ratio (L/D ratio), and velocity could be increased, boosting penetration performance. This change over the older AP and APDS rounds made the use of a kinetic energy round in the form of APFSDS more practical from low pressure guns.
The APFSDS round would still be somewhat inferior in penetration performance compared to a HEAT round for the 90 mm low pressure guns, but the gap was closed. The APFSDS round which was developed on the EE-9 was rated to penetrate a NATO single medium plate at 1,100 meters (1,200 yards), or 130 mm (5.1 inches) at 60° at 1,100 meters. Interestingly however, a later APFSDS round from Cockerill with fairly similar specifications is only rated in Cockerill’s brochures as 100 mm (4 inches) at 60° at 1,000 meters. Although there is variation as to exactly how these tests were conducted, it seems logical to assume that the APFSDS round of Engesa penetrated anywhere from 100 to 130 mm at 60° at 1,000 meters. Comparatively, this is marginally worse than the HEAT round, which is rated at 130 mm at 60° at any range.
It is also interesting to note that Engesa marketed the APFSDS round not as being a better round than the HEAT round in penetration performance, but in terms of the hit probability. The APFSDS boasted a higher but still relatively low muzzle velocity of 1,175 m/s, compared to the 890 m/s of the HEAT ammunition. However, the velocity increase and the much smaller projectile meant that accuracy of the APFSDS round at 1,000 meters was doubled from 0.8 mils (0.8 meters at 1,000 meters) dispersion of the HEAT round to 0.4 mils (0.4 meters at 1,000 meters). Additionally, the effective range doubled as well from 1,000 m to 2,000 m and the maximum range increased from 2,100 m to 3,000 m. Effectively, the APFSDS round offered a more accurate round at the price of only a small reduction in penetration which could still pose a theoretical threat to tanks like the T-55 family and the M48 Patton.
Development and Testing
Development of the APFSDS round started at an unknown date, but due to the dates available on later images and Engesa’s tendency to quickly design and develop new equipment, it is thought development started in 1984. At this point, Engesa would have had some experience in the role of APFSDS in armored vehicle design with the EE-T1 Osorio tank project which started in 1982. Additionally, the Brazilian subsidiary Engequímica, which designed the ammunition, was founded in 1984.
Engequímica designed a saddle/spool type APFSDS round in accordance with NATO style APFSDS rounds of the time period. The engineers supposedly considered both steel and tungsten for the penetrator, but went with the more capable tungsten in the end. This would be essential, considering the penetration gap to be bridged between the APFSDS and HEAT rounds for the APFSDS to be a viable option.
The tungsten penetrator had a 16:1 L/D ratio, with a diameter of 20.2 mm (0.8 inches) and a length of about 323 mm (12.7 inches). The penetrator and sabot combined weighed 2.9 kg and the sabot itself 1.8 kg. The sabot was most likely made from aluminum, like most other sabots were, making up about 38% of the projectile launch weight. The sabot weight was on the heavier side of the spectrum, as sabots tended to weigh about 30 to 39% of the total projectile launch weight at the time.
A disassembled APFSDS round of Engequímica.
Source: Jane’s Armour and Artillery 1986-1986
As previously mentioned, development likely started in 1984, and an image dated in October at an unknown year may suggest that live firing trials with the new round were initiated around that period. This is because later images of testing appeared in May 1985 and the testbed appeared in July 1985. Considering no APFSDS acquisition was requested after the testbed was presented, it is assumed that further development of the APFSDS round was canceled. This is further supported by an ex-Engesa employee noting that they never fixed some of the design issues, suggesting that the development was shelved as no interest was shown.
The EC-90 gun with the pepperpot style muzzle brake, note the triple baffle muzzle brake placed on the floor underneath.
Source: Edson Kiyohara
A Matter of Muzzle Brakes
The image of testing in October also excellently illustrates one of the main issues of APFSDS ammunition for light weight platforms. In the image, the standard triple baffle muzzle brake was placed on the ground and a so-called pepper pot muzzle brake was mounted on the gun instead. Complicated multi-stage muzzle brakes tend to interfere with the proper separation effect of the sabot, as the sabot would start to separate prematurely inside the muzzle brake.
Ex-Engesa employee Edson Kiyohara, assigned to the Engequímica program, noted that they tested the APFSDS rounds on both muzzle brakes to see if the triple baffle muzzle brake could be used. According to him, Engequímica first tested the standard Cascavel muzzle brake, but that the muzzle brake was damaged by the sabot separating inside.
As a result, Engequímica switched to the much simpler pepper pot muzzle brake, which is not much more than a steel tube with holes drilled into it to redirect the propellant. Since the pepperpot effectively acted as an elongation of the gun barrel, the sabot would not separate in the muzzle brake, as it would not get the required space to split. However, due to its simple nature, the effectiveness of limiting the gun recoil force was reduced compared to the standard muzzle brake. As a result, premature wear or a less comfortable vehicle for the crew to be in while firing the gun would be the compromise. Additionally, the increased trunnion pull force would also mean that the gun became less suitable for lighter vehicles, although this was less of a problem for the EE-9.
Had the APFSDS round for the EE-9 actually caught on, it would not be surprising if Engequímica would have switched to the single baffle muzzle brake, as on the French guns, of which the 90 mm F4/CN90 BR3 on the Tamoyo 1 tank was an excellent example. Supposedly, these muzzle brakes were more effective than the simple pepper pot muzzle brakes. Eventually, Engequímica could also have taken inspiration for a more advanced pepperpot design as on the B1 Centauro, as Engequímica would use the same 105 mm OTO-Melara gun on the EE-18 Sucuri tank destroyer.
Further testing of the APFSDS round itself seems to have been carried out in May 1985, as multiple images appear of the gun and the round at the Marambaia testing grounds. The tests included penetration tests and sabot separation tests, according to an Engesa/Engequímica employee present.
An Engesa Employee holding the 90 mm APFSDS round.
Source: Edson Kiyohara
The sabot separation tests seem to have not been much more than a mesh fixed to a wooden frame at which the APFSDS round was fired. The goal of the test was to see if the sabot separated more or less equally and this could be tested to by observing if the distances between the projectile in the middle and the three sabot spreads was more or less equal. In the image available, the APFSDS round fired showed a satisfactory sabot spread.
The excellent sabot spread during a test.
Source: Edson Kiyohara
The penetration tests were essentially firing the APFSDS round at a target consisting of a number of spaced steel plates. The gun was mounted in a static gun mount which was positioned 250 meters away from the steel plates. Each steel plate was 25 mm thick and placed vertically with a gap of 25 mm of air in between each plate. This would dampen the kinetic energy and blunt the APFSDS round as it would be subjected to various impact shocks while going through the plates. As a result, the APFSDS round managed to penetrate just 2 plates during this test.
Interestingly, this test seems to undercut Engesa’s brochure claim that the APFSDS round could penetrate a triple medium NATO target at point blank range. For a triple medium target, the round would have to penetrate a 10 mm, a 25 mm and finally a 60 mm plate. Considering the 25 mm plate penetration tests were done at 250 m on a 90 mm gun, this would have been the equivalent of a point blank test.
Steel target plate penetrated by the 90 mm APFSDS round.
Source: Edson Kiyohara
The claim that the APFSDS round could penetrate a NATO single Medium target was not, however, impossible. The previously mentioned similar Cockerill round was rated to be able to defeat 100 mm of steel armor at 60° at 1,000 m. Considering NATO penetration standards required 50% of the rounds to go through to rate it at a penetration, it would not be unfeasible if Engesa simply listed the higher potential estimate to make the round look more appealing on paper.
Presentation of the EE-9 APFSDS Testbed
In July 1985, an Iraqi delegation visited the Marambaia proving grounds to receive a presentation of the various projects which Engesa was carrying out for Iraq and other countries at the time. Among the vehicles presented were the prototype ET-25 armed Cascavel on the standard hull, the EE-9 with the pepper pot muzzle brake for the APFSDS test batch, and the EE-T1 P0 Osorio mock-up.
The vehicles were shown and some test firing was carried out. It does seem that Iraq had no real interest in the APFSDS round, as no further images of the EE-9 with the pepper pot muzzle brake seem to have appeared and the APFSDS round development never got further than the initial test batches. It is quite likely that the lack of interest of the Iraqi delegation in the round would have caused further development of the round to have been shelved until a customer showed serious interest in acquiring it again.
The EE-9 APFSDS testbed during the visit of the Iraqi delegation.
Source: Claudio Agostini
EE-9 M4 APFSDS Testbed in Detail
The EE-9 M4 APFSDS testbed weighed around 12.5 tonnes (13.8 US tons) combat-loaded. It was an estimated 6.3 m (20.7 feet) long including the gun and 5.25 m (17.2 feet) without the gun. It was 2.59 m (8.5 feet) wide, about 2.29 m (7.5 feet) tall to the top of the turret and 2.6 m (10.5 feet) tall to the top of the ET-7.62 commander’s cupola. The EE-9 M4 had a crew of three, consisting of the commander/loader (turret left), gunner (turret right), and the driver in the middle front hull.
A rear image of the EE-9 with the prototype ET-25 turret.
Source: Claudio Agostini
Hull
The hull of the EE-9 M4 was manufactured from welded bimetallic steel plates. The hull also featured two covers which were mounted on the hull above the Boomerang suspension, effectively functioning as mudguards and very minor spaced armor. These mudguards could also have recesses in the middle, as on the Iraqi EE-9 M4s, to stow additional jerrycans.
The front upper hull plate presented 16 mm (0.63 inches) of bimetal armor at an angle of 60º. The sides and rear were 8.5 mm (0.33 inches) thick at varying angles, and the top and bottom hull were 6.5 mm (0.26 inches) thick. The front of the EE-9 was meant to protect from .50 caliber machine gun fire at an unknown range, while the entire vehicle was protected from 7.62 mm AP rounds at 100 m (109 yards), and standard 7.62 mm rounds at 50 m (54 yards).
The average effectiveness of the bimetallic plates was about 1.8 times the thickness of an equivalent homogeneous plate against 7.62 mm or 1.5 times the thickness against .50 caliber machine gun fire. This meant that, against .50 caliber machine gun fire, a 16 mm bimetallic plate could be used instead of a 25 mm homogenous steel plate. These protection advantages over homogenous plates effectively meant that the Cascavel saved a lot of weight without compromising protection. The outer layer would shatter and blunt the incoming projectile, while the inner layer would relatively move with the bullet, slowing it down and stopping it without shattering.
The EE-9 M4 had two headlights and black-out lights integrated in both sides of the lower front plate. A rearview mirror could be mounted on both sides of the upper front plate. Below the driver’s vision block was a foldable windshield, which the driver could use when driving with an open hatch. The driver had access to 3 periscopic sights mounted in a sort of vision block in front of him. The driver’s rotating sliding hatch was part of the top plate and was located behind the vision blocks. These periscopes and other periscopes or sights would not have been active or passive night vision equipment unless the Cascavel was ordered with these devices. The standard periscopes were manufactured by D.F. Vasconcellos.
A frontal view of a Colombian EE-9 M4 showing the headlights, the windscreen, and the 3 periscopes.
Source: Rodolfo Alberto Riascos Rodriguez
A ventilation inlet was installed on both upper hull side plates. These ventilation inlets are recognizable by their frustum shape. A siren was installed behind the ventilation inlet on the right side of the vehicle. The fuel tank cap of the Cascavel was located on the left side, in the middle of the upper side hull plate, with the fuel tank installed on the hull floor. The EE-9 had a large ventilation grille on the rear of the vehicle, reminiscent of the M8 Greyhound, and had a rear light on both sides of the ventilation grill. The engine could be accessed through two large hatches on the hull top rear. The engine exhaust was located on the top right rear plate, as was unique to the EE-9 M4s.
An interior sketch of an EE-9 M4.
Source: EE-9 M4 Manual
The M4 used an adjustable ZF 8062 hydraulic powered steering wheel and had two pedals: the throttle on the right side of the steering wheel, and the brake to the right of the throttle. The gear selector was located to the right of the driver and the hand brake was located to the left. A control panel was located on the front left of the driver for, among other things, the headlamps, siren, windshield, the various meters, and interior lighting. To the right was the pressure selector for the central tyre inflation system.
Mobility
The EE-9 M4 used the Detroit Diesel 6V53N V6 engine, which produced 212 hp at 2,800 rpm and 598 Nm at 1,800 rpm. The engine had a total cylinder capacity of 5.212 liters, with a cylinder diameter of 98 mm and a stroke of 114 mm. The M4 Cascavel had a top speed of 95-100 km/h (59 mph) and an operational range of 750 km (466 miles).
It had a turning radius of 8.12 m (8.88 yards) and it could ford a depth of 1 m (3.3 feet) without additional preparation. The Cascavel could climb a 65º slope, could climb a vertical obstacle of 0.60 m (2 feet), cross a 1.65 m (5.4 feet) trench, and had a ground clearance of about 0.5 m (1.6 feet). The front-wheel could travel for 0.2 m (0.66 feet), while the rear wheels could travel for 0.9 m (3 feet). It used 12 x 20 run-flat tires which were 0.5 m (1.6 feet) wide. The EE-9 M2 had a distance between the front axle and rear axle of 3.05 m (10 feet), and a distance of 1.4 m (4.6 feet) between the two rear wheels.
The EE-9 M4 used an automatic Detroit Allison MT-643 transmission with four forward and one reverse gears. The transmission system could handle up to 250 hp and was the only transmission used in the EE-9s which could mount the Detroit 6V53 engine. The M7s would also use this transmission, but they were never paired with a Detroit when they were sold by Engesa.
In addition, the Cascavel used an Engesa 2 speed transfer case, which allowed the Cascavel to be used in reduced and high gear. By putting the Cascavel in reduced gear, horsepower was sacrificed for increased torque, making it more effective in climbing slopes. The vehicle was 6 x 6 driven, of which the rear 4 wheels were part of the Boomerang suspension. The Boomerang suspension, in combination with the Engesa 2 speed transfer case, enabled the Cascavel to cross challenging terrain and provide maximum traction in most situations.
The drivetrain of an EE-9.
Source: Engesa Manual
The power of the engine was distributed to a differential on the front side of the vehicle, and a differential in the rear. The rear differential drove the Boomerang suspension with a single axle, which made the Boomerang suspension such an ingenious design.
In 1969, this suspension was invented by Engesa to enable trucks to transport oil to the refineries through rough terrain with bad infrastructure. With this suspension, the trucks could traverse otherwise untraversable hills for conventional suspension systems, as the wheels would always stay in contact with the ground to provide maximum traction.
The suspension system was a two wheeled-single axle driven suspension. The advantage of the Boomerang suspension was that it could be fitted on existing differentials with a single axle. Normally, this meant that the single axle, designed for the torsion forces of a single wheel, was subjected to the torsion forces of two wheels. Through excellent engineering, half of the torsion forces of the two wheels were mitigated by the suspension system built around the original axle. This design not only enabled the drive of two wheels by a single axle but, with clever usage of gears and bearings on both the axle and tube around the axle, the suspension system can rotate around its axle for 360º. This ability to rotate in extreme angles would enable the vehicles to traverse very difficult terrains and still provide maximum traction, as the suspension system curved with the terrain so that all the wheels were always in contact with the ground.
Exploded view of a Boomerang suspension.
Source: Engesa Manual
The Boomerang suspension used leaf springs for dampening. The two front wheels were used for steering. The wheels on the Boomerang suspension all rotated at the same speed. The front wheels were dampened by large coil springs. The vehicle used hydraulic disc brakes, and was steered with hydraulics as well.
A Central Tyre Inflation System (CTIS) came standard with the M4s. This system would help in obtaining the appropriate traction at various speeds by regulating the tyre pressure. This could help in crossing rough terrain but also save fuel. This was done by the driver through a switch. A Bendix Tu-flo 500 air compressor was used to provide the air flow and pressure for the CTIS.
Turret
The EE-9 APFSDS testbed used an all-welded bimetallic steel construction to protect against small arms fire. The ET-90 II turret had 16 mm of armor at the front and 8 mm of armor at the sides, rear, and top. The turret had a hatch for the commander/loader on the left and the gunner on the right. The commander’s position could also incorporate the ET-7,62 commander’s cupola. The turret had access to a pistol port on the left side to remove spent casings from the turret, and 3 smoke launchers on each side rear of the turret. Additionally, the turret was provided with 4 lifting hooks, an illumination lamp at the front and a stowage rack on the rear.
The ET-90 II turret.
Source: Engesa Manual
The ET-7,62 commander’s cupola was armored with 8 mm bimetal steel plates angled at 15° from vertical minimum and had a 680 mm diameter turret ring. It mounted a gun mount for a 7.62 mm machine gun, although the EE-9 APFSDS used an ET-50 gun mount for a .50 caliber machine gun instead. This seems fairly characteristic for the Iraqis at the time, who were said to have a preference for using heavy machine guns against helicopter ambushes of the Iranians during the Iraq-Iran war. The machine guns could be fired remotely from the inside and were provided with a reticule in the sight, but also a simple steel ring in front of the middle sight. The cupola had access to 5 sights, of which the middle front sight could use an SS-130 day-night sight. The SS-130 sight was an image intensifier sight with no magnification. The commander also had access to two periscopes on the front sides, and direct vision sights on the rear sides. The commander used a manual drive to rotate the cupola.
The ET-7.62 commander’s cupola.
Source: Engesa Manual
The gunner was located on the right and had access to a day/night sight for the main gun. This was an SS-122 sight on the Cascavels, an image intensifier sight which provided 10x magnification for the day sight and 9x for the passive night vision channel. The sight mirrors were coupled to the main armament to allow for automatic elevation of the sight mirrors in accordance with the gun elevation.
The SS-122 gunner’s sight.
Source: Jane’s Armour and Artillery
The commander was also the loader of the vehicle, having 12 rounds located in the turret bustle on the left side and 12 rounds in two 6-round revolver style magazines behind both the gunner and commander/loader. He had 8 boxes of machine gun ammunition in front of him and another box to his rear. The coaxial machine gun was located to the left of the gun, in front of the commander/loader and also housed a box of ammunition, for a total of 11 boxes when including the machine gun on the commander’s cupola.
The ET-90 II turret basket. Note the straight turret basket rods instead of the tapering rods of the ET-90 I turret.
Source: Engesa Manual
The electronics, like intercoms, control boxes for the sights and switches were located to the right of the gunner, while the radios were located in the turret bustle. The SS-122 sight was in front of him, with a control box for a laser rangefinder to his front left. As the EE-9 APFSDS testbed did not mount a laser rangefinder on top of the gun, it is unclear if the control box was in the vehicle. It is likely that Engesa did not mount it, as the vehicle was only used for test firing at a range with the distances already known. The gunner had access to 3 more periscopes, of which 2 were located on the side of the turret and 1 to the rear of the gunner. The gunner used manual drives to elevate the gun and to rotate the turret. Although Engesa did market an electric drive system, it is unknown if this system was ever sold to any country.
The electronics to the side of the gunner.
Source: Engesa Manual
Armament
The EE-9 APFSDS testbed used a modified EC-90 III cannon as its main armament. The EC-90 was a licensed production of the 90 mm Cockerill Mk.3 gun, obtained in 1975, and was 36 calibers long. This resulted in a barrel length of 3.24 meters (10.6 feet) excluding the muzzle brake. As the muzzle brake was replaced with a less efficient one to enable the use of APFSDS, it was quite likely that the recoil force increased as a result. It would have been possible to increase the gun recoil stroke from the standard 500 mm to 530 mm (19.7 inches to 20.9 inches) to help mitigate the inefficiency of a pepperpot muzzle brake design.
EE-9 M4 APFSDS testbed ammunition
Round
Capability
Maximum range
Velocity
APFSDS (Armored Piercing Fin Stabilized Discarding Sabot)
100 to 130 mm at 60° from vertical at 1,100 meters.
3,000 meters (3,280 yards)
1,175 m/s
HEAT – NR 478A1 (High Explosive Anti-Tank)
250 mm-300 mm (9.8-11.8 inches) flat at any range and 130 mm at 60° from vertical at any range.
2,000 meters (2,185 yards)
890 m/s
HESH – NR 503A2 (High Explosive Squash Head)
Meant for bunkers, walls and light vehicles.
2,000 meters (2,185 yards)
800 m/s
HE – NR 501A1 (High Explosive)
Lethal radius of 15 meters (16 yards)
1,600 meters (1,750 yards)
700 m/s
White Phosphorus – Smoke – NR 502A2
50 meter wide smoke screen for 20 to 30 seconds
1,600 meters (1,750 yards)
695 m/s
HEAT-TP – NR 479A2 (High Explosive Anti-Tank – Training Projectile)
Inert (no explosive filling)
2,000 meters (2,185 yards)
750 m/s
The firing table and the ‘crosshair’ of the direct-fire telescope for the EC-90 gun went up to 3,000 m for the HEAT round, 2,380 m for the HE and smoke round, and 1,020 m for the coaxial machine gun. The main armament was fired with a pedal on the turret basket floor and could be cut off through the main electrical system box. This box controlled things such as the ability to fire the main and coaxial armament, configure the ventilation system, and internal lights. In some EE-9s, the firing table was added as a plate on the electrical system box as well. The electrical system box was mounted to the right of the gunner. Additional control boxes would be added for equipment such as laser rangefinders and day/night sights if needed.
The ammunition for the EC-90 gun lined up from left to right: HE, HEAT Training Projectile, HESH, HEAT, Smoke.
Source: Jane’s Armour and Artillery 1985-1986
The ET-90 II turret of the APFSDS testbed used a 7.62 mm FN MAG M971 machine gun as its coaxial armament and had a .50 caliber machine gun mount on the ET-7.62 commander’s cupola. In theory, the M971 could fire up to 1,000 rounds per minute, while the practical rate of fire was about 600 rounds per minute. Its maximum practical range was 1,200 m and it weighed 2.8 kg. The coaxial machine gun was installed on the commander’s side, as the commander acted as the loader, but was fired by the gunner through a button on the main gun’s elevation handle. It could be manually fired by the commander if needed. The gun had an elevation of 15° and a depression of -8°. The EE-9 carried 2,200 rounds of 7.62 ammunition, divided between 11 cases, and a total of 44 rounds for the main gun, of which 20 were stored in the hull and 24 in the turret.
Sketch of the M971 machine gun.
Source: Engesa Manual
Cancellation and Unsolved Issues
When the APFSDS round development was exactly canceled is unknown. Considering the Iraqis did not seem to take interest in it in July 1985, it is quite likely the APFSDS round development was canceled soon after, as they would be Engesa’s most likely buyer for the APFSDS. It is also a possibility that the Iraqis did not have the money to acquire such a niche round as, from 1985 on, the Iraqi finances started to gradually run out due to the Iraq-Iran War. According to one of the engineers who worked on the project, a number of issues with the APFSDS round were never resolved.
The rifled gun posed a number of challenges for the APFSDS round to work properly, as the round was not supposed to spin when leaving the barrel. The rifling meant that pressure had to be limited, but it also damaged the so-called nylon obturator ring holding the sabot together and supposedly the sealing ring. Another challenge was finding out the proper depth for the so-called buttress threading on which the sabot is placed to allow it being forced through the barrel by the pressure, but also split when the projectile leaves the barrel. When machined too shallow, the sabot would not split, but when machined too deeply, the sabot would split too early in the barrel. The engineer was convinced they could have fixed these issues, had the project not been canceled. Additionally, it would be quite likely that, had the project gone through, Engesa would have offered a more efficient muzzle brake design than the pepperpot.
Why exactly the project was canceled is unknown as well, but a number of indicators point towards multiple reasons on why a customer would prefer to stick with the HEAT ammunition instead. The first is that the APFSDS round does not offer any penetration performance advantage over the HEAT round. It was more accurate and offered a better effective range, but it can be questioned how much the increased effective range would actually be utilized, as the penetration performance would drop further as well. Additionally, and perhaps the main reason, the APFSDS round would have cost about US$630 each, compared to about US$460 for the HEAT round. This meant that a customer would be paying US$170 more for a less versatile and worse performing round for a little increased accuracy and range, of which the latter may or may not be used too much.
While Engesa never seems to have considered this, it would have perhaps been a better idea if it had started offering a more anti-tank focused gun instead for the EE-9. These could have been the 60 mm HVMS, although this gun lacked the ammunition versatility of the EC-90, or, perhaps more competitively, the 90 mm F4. The 90 mm F4 was a high pressure and high velocity gun which was already in Brazil in 1984, as it was mounted on the Tamoyo 1 in 1984. The 90 mm F4 was also mounted on the French ERC-90 Sagaie 6×6 wheeled vehicle, which meant that the EE-9 could have directly competed with it. In essence, the 90 mm F4 used the same ammo as on the French 90 mm D921, but also introduced an APFSDS round. As such, Engesa could have simply refitted their existing projectiles for his gun as well, but with modified casings.
However, from a different point of view, most of the larger Sagaie sales already happened at the turn from the 70s to the 80s and only about 20 were sold after 1984. Additionally, the Sagaies could be sold with much more advanced systems, like stabilization, a linked fire control system, a semi-autoloader, and electro-hydraulic turret drives. The EE-9 would either have to be sold with a similar fire control system or be sold as a cheap and simple upgunned competitor instead.
The fate of the EE-9 M4 APFSDS testbed is unknown. It is likely that it remained as a test vehicle for Engesa with the pepperpot muzzle brake removed, but its fate after Engesa’s bankruptcy is unknown. It was likely either sold to one of the legacy companies, like Universal or Columbus, scrapped, or potentially sold to Iraq in the last batch of EE-9s sold in 1985. A number of Engesa vehicles, like both Osorio tanks and the EE-3 Jararacas, would initially end up with the 13th RCMec in Pirassununga, but this does not seem to have happened with the testbed.
Conclusion
In the end, the costs of the APFSDS round for the EE-9 simply outweighed the minor benefits it brought to the table. The performance was lacking and the price tag did not justify the increased accuracy and extended range compared to the HEAT ammunition. It would have perhaps been more effective if Engesa had decided to offer a more dedicated anti-tank version, although this would have been a much more expensive vehicle with perhaps a very limited market. An APFSDS shooting EE-9 ended up as a dead end.
EE-9 M4 APFSDS Testbed. Illustrations by Godzilla funded by our Patreon Campaign.
Specifications (EE-9 M4 ET-25)
Dimensions (L-W-H)
6.3 x 2.59 x 2.29 m (20.7 x 8.5 x 7.5 feet)
Total weight
12.5 tonnes (13.8 US tons)
Crew
3 (driver, commander, gunner)
Propulsion
Detroit Diesel 6V53 212 hp engine (or OM352A 172 hp engine)
Speed (road)
95-100 km/h (59 mph)
Operational range
750 km (466 miles)
Armament
90 mm KBA cannon
7.62 mm FN MAG (coaxial)
Optional .50 machine gun (turret top)
Armor
Hull Bimetal
Front 16 mm (0.63 inches)
Side 8 mm (0.32 inches)
Rear 8 mm (0.32 inches)
Top 6.5 mm (0.26 inches)
Floor 6.5 mm (0.26 inches) ET-25 turret (Estimated)
Front 16 mm (0.63 inches)
Side 8 mm (0.32 inches)
Rear 8 mm (0.32 inches)
Top 8 mm (0.32 inches)
Produced
1
Special thanks to Expedito Carlos Stephani Bastos, the leading expert of Brazilian armored vehicles https://ecsbdefesa.com.br/, Jose Antonio Valls, an Ex-Engesa employee and expert in Engesa vehicles, Paulo Bastos, another leading expert of Brazilian Armored vehicles and the author of the book on Brazilian Stuarts and the website https://tecnodefesa.com.br, Adriano Santiago Garcia, a Captain in the Brazilian Army and ex-company commander on the Leopard 1 and ex-lecturer on the Brazilian Armored School, and Guilherme Travassus Silva, a Brazilian with whom I was able to endlessly discuss Brazilian Vehicles and who was always willing to listen to my near endless ability to talk about them.
Sources
Engesa EE-9 Cascavel 40 anos de combates 1977-2017 – Expedito Carlos Stephani Bastos
Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020 – Expedito Carlos Stephani Bastos Blindados no Brasil – Expedito Carlos Stephani Bastos
Engesa manuals
Engesa brochures
Dual Harness skin stops armor-piercing projectiles Article of Richard M. Ogórkiewicz Technology of Tanks – Richard M. Ogórkiewicz
Personal correspondence with Ex-Engesa Employees
Personal correspondence with Expedito Carlos Stephani Bastos
Personal correspondence with Paulo Roberto Bastos Jr.
EE-9 M4 Cascavel armed mounting the ET-25 turret. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.
Federative Republic of Brazil (1985)
Wheeled Anti-Aircraft Vehicle – 1 Built
As the Iraq-Iran War was raging on, Iraq was searching for anything which might be able to swing the conflict in its favor. To accomplish this, Iraq sought help from a rising powerhouse in the defense export world to help bring this advantage. The rising Brazilian defense industry had interesting and functional concepts, but most importantly, Iraq could buy its loyalty and heavily fund the industry for it to develop new equipment fully catering to Iraqi requirements.
One of these projects was to fill the requirement of a wheeled anti-aircraft screening vehicle to help cover the Iraqi convoys from Iranian helicopter attacks. Iraqi Army officials contacted the Brazilian company Engesa, which had previously delivered 364 EE-9 Cascavels and 148 EE-11 Urutus, to suggest that the Iraqi Army would be willing to acquire such a vehicle if the company could develop a suitable solution.
As such, Engesa went to work. The company decided that developing a 25 mm autocannon armed turret to be mounted on the EE-9 Cascavel was the way forward, and so, the EE-9 with ET-25 turret was born.
The EE-9 M4 Cascavel armed mounting the ET-25 turret.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
The EE-9 and Iraq
The story of why the EE-9 Cascavel (English: Rattlesnake) was developed can be traced back to the Second World War. Brazil sent an expeditionary force, known as the ‘Smoking Snakes’, to fight in Italy alongside the Allies. During the Italian campaign, the Brazilian forces were armed with the M8 Greyhound. The Greyhound turned into the most loved vehicle by the Brazilian soldiers, and after WW2, this love would remain embedded in the Brazilian Army.
Although Brazil enjoyed its diplomatic relations with the United States well into the 1970s, the first steps to break free from the United States, from an army materiel point of view, started in 1967. The United States got increasingly involved with the Vietnam War and, as a result, could not supply Brazil with the cheap equipment it once did. As such, it was decided that the Army would try to develop their own armored vehicles.
One of these was the EE-9 Cascavel, which was passed on to Engesa for production after the Army had developed a number of prototypes. Engesa managed to secure an export deal with Libya for 200 EE-9s in 1974 and soon after would receive an order for an additional 200 vehicles. From there, the EE-9 became Engesa’s flagship product, as they would sell it to multiple South American countries as well.
The usage of the EE-9 Cascavel by Libya and its export success managed to get the attention of Iraq. After three weeks of negotiations, Engesa managed to secure the export contract for 364 EE-9s and 148 EE-11s on May 5th 1978. Iraq would be the first to receive a new model of EE-9, known as the EE-9 M4. In contrast to previous models, the EE-9 M4 used an MT-643 transmission which could handle the more powerful Detroit Diesel 6V53 212 hp engine. In addition, the hull featured a number of redesigns like the integration of the headlights in the lower hull plate instead of the installation on top of the upper front plate. The most significant change was the redesigned ET-90 turret, known as ET-90 II, which was able to incorporate night vision sights.
Iraqi EE-9 M4s lined up.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
This deal started the arms relations between the two countries for the next 13 years. This relation would eventually morph into Iraq becoming virtually the most important customer for the Brazilian defense industry. The start of the Iraq-Iran War in 1980 and the subsequent stalemate would catapult the Brazilian defense industry into its golden age. Systems like the successful ASTROS rocket launcher, the Piranha air-to-air missile, and the EE-T4 Ogum were mostly funded and specifically built to cater to the Iraqi market. An EE-9 for anti-air purposes was also requested by the Iraqi Army.
The Iraq-Iran War saw the most intensive use of helicopters of any conventional war up to that point. Early on, Iraqi tank convoys were attacked and successfully destroyed through the use of TOW and Maverick air-to-surface missile armed AH-1J helicopters. In order to protect these convoys from so-called pop-up attacks, the Iraqi Army sought a vehicle which could act as an anti-helicopter screen and that could immediately engage an enemy helicopter when the convoy was ambushed or when it encountered it. As such, infantry dismounts with surface-to-air missiles and especially expensive and vulnerable surface-to-air missile systems which needed time to be deployed were less suitable for this role.
The requirements and request for the development of such a screening vehicle were supposedly passed on to Engesa by General Amer Rashid at an unknown date. Considering Engesa’s ability to develop prototypes very rapidly (the EE-T4 Ogum prototype was developed and built in just 6 months), it is quite likely that this request was made somewhere in late-1984 to early-1985. In any case, Engesa went to work.
How the development process exactly went is unknown. It is likely that Engesa looked at the platforms they had available, which were in service with the Iraqi Army, and which were suitable to receive such a role. Engesa likely selected the EE-9 to be used for the anti-aircraft concept as it already drove alongside the armored columns. The Cascavels were used as reconnaissance vehicles and thus were already used to screen the armored columns against potential ground targets. An anti-aircraft EE-9 could still be used in a similar way for reconnaissance but with the emphasis laying on air targets instead.
Turret Designations
Before going into the turrets designed for the 25 mm armed Cascavel, it is perhaps useful to clarify a number of things regarding designation. As far as is known, two ET-25 turrets were made. The first seems to have been converted from the pre-existing ET-90 II turret of the standard EE-9. The second was an actual ET-25 turret which was designed from the ground up.
The first prototype ET-25 turret.
Source: Claudio Agostini
Normally, as with the ET-90 turrets, the first could be designated ET-25 I and the second ET-25 II. Since there is no documentation regarding how Engesa itself designated the turrets, the first turret will be designated in this article as the ET-25 prototype. The second turret will simply be designated ET-25.
The ET-25 turret.
Source: Jane’s Armour and Artillery
Developing the ET-25 Turret
According to earlier sourcing from the Brazilian armored vehicle expert Expedito Carlos Stephani Bastos, the very first prototype turret built by Engesa was suspiciously identical in every way to the T 25 turret from OTO Melara. While there is the extremely remote possibility that Engesa copied the T 25 turret, it seems extremely unlikely. The turret also does not fit the more functional and simplistic design style of the company either. As such, it is very unlikely that this turret was built by Engesa, which seems to be supported by the fact that the turret is omitted from later works of Expedito Carlos Stephani Bastos.
The T 25 turret.
Source: Engesa EE-9 Cascavel 40 anos de combates 1977-2017
There is still a possibility that the T 25 turret influenced the ET-25 turret from Engesa instead. The interior layout seemed to be somewhat similar and the overall shape in the later design stages of the ET-25 turret started to resemble a more functional and simplified version of the T 25. In the early stages, however, Engesa quite simply seemed to have taken the ET-90 turret and adapted it to be armed with the Oerlikon 25 mm KBA autocannon.
A cut-out depression on the right side of the turret was made to facilitate a shell case ejection system, like on the T 25. What does stand out is that while the turret seems to be based on the ET-90 II turret, it does differ in hatch opening concept. From the ET-90 II on, the crew hatch of, for example, the gunner hinged open toward the front, protecting the front of his body when leaving the vehicle. The initial ET-25 prototype turret had both the hatches for the gunner and commander open towards the rear, like in the older ET-90 I design.
The ET-90 II turret.
Source: Engesa Manual
It is interesting to note that the Osorio composite armor variant was developed through the use of an Oerlikon 25 mm autocannon as well. Scale models of the composite armor package were tested by shooting at them with the autocannon to simulate the impact 105 and 120 mm tank rounds at the CTA (Centro Técnico Aeroespacial, Aerospace Technical Center). When this was carried out is unknown, but it seems to have been done before 1985, as the CEO of Engesa claims the composite armor was ready in an interview in 1985. As such, it is a possibility that the 25 mm autocannon used to test the Osorio composite is the same 25 mm which ended up arming the ET-25 turret, as it was already in the country and had no other use. This lines up timetable wise, as the first testing of the ET-25 prototype turret was carried out in April 1985.
The EE-T1 P0 Osorio mock-up with the EE-9 ET-25 prototype in the background in July 1985, when an Iraqi delegation examined both vehicles.
Source: Claudio Agostini
The EE-9 with the ET-25 Prototype
The first picture of an EE-9 mounting a prototype ET-25 turret was taken in April 1985 at the Marambaia proving grounds. According to the ex-Engesa employee Edson Kiyohara, the turret was ready and tested as well at that moment. What is perhaps even more interesting than the ET-25, is the EE-9 it was mounted on. The EE-9 shown in the picture is perhaps the single rarest EE-9 Cascavel to have existed, as it uses wheel hubs with planetary gears.
The EE-9 testbed carrying the prototype ET-25 turret in April 1985.
Source: Edson Kiyohara
No EE-9 in service ever used such a system and it only ended up being used on the EE-11 M7 Urutu versions. The advantage of such systems is that they have much better power and torque transmission efficiencies over conventional designs. Drive shafts suffer only a third of the torque over conventional systems as well.
In July 1985, the turret was mounted on a standard EE-9 M4 hull. An EE-9 M4 can be distinguished from the other EE-9s due to the engine exhaust being located on the top right rear plate. Only Detroit powered EE-9s had this exhaust placement style and only M4s are known to have mounted Detroit 6V53 engines. While EE-9 M7s could mount such an engine as well due to them also having an MT-643 transmission, they seemingly were never acquired with them. The likely reasons for this ranged from pre-existing logistical structures to increased costs of about US$20,000 per vehicle, with less capital heavy customers being the main buyers of the EE-9 M7.
The EE-9 M4 with the prototype ET-25 turret in July 1985.
Source: Claudio Agostini
The July 1985 Iraqi Delegation
In July 1985, an Iraqi delegation visited the Marambaia proving grounds to receive a presentation of the various projects which Engesa was carrying out for Iraq and other countries at the time. Among the vehicles presented were the prototype ET-25 armed Cascavel on the standard hull, an EE-9 with a pepper pot muzzle brake for the APFSDS test batch, and the EE-T1 P0 Osorio mock-up.
The Iraqi delegation examining the EE-9 with the ET-25 prototype turret, with the EE-9 APFSDS testbed in the rear. Note the muzzle brake of the APFSDS testbed.
Source: Claudio Agostini
The vehicles were shown and some test firing was carried out. The concept was something of a success, as Engesa started designing a brand new 25 mm armed turret from the ground up. It would not be unsurprising if the converted ET-90 turret was a proof of concept to gauge the Iraqi interest in a 25 mm armed Cascavel.
The prototype ET-25 turret test firing for the Iraqi delegation.
Source: Claudio Agostini
Redesigned ET-25
With the seeming enthusiasm secured from the Iraqi delegation, Engesa set off developing a new turret. The turret was smaller in shape and more in line with what was needed to house the 25 mm gun. The turret bustle was reduced in size, as it did not need to store 90 mm ammunition as on the ET-90. and the front tapered off much more heavily due to the much smaller breach of the 25 mm. In addition, a round commander’s cupola was introduced for the commander to have better vision around the vehicle and a searchlight was introduced on the front left side of the turret.
The round commander’s cupola and the searchlight.
Source: Jane’s Armour and Artillery
While the turret was more in line with the needed size to house the 25 mm gun, it was just 50 kg lighter, at 2200 kg, than the ET-90 turret, which weighed 2250 kg. This most likely had to do with the introduction of electric turret drives. As far as is known, no ET-90 turret ever received electric turret drives when they were sold by Engesa. The turret drives would have been heavy and above all, they cost as much as the entire turret itself. For the ET-25 however, electric turret drives were a must to help the crew in dealing with more nimble and faster helicopters.
It is interesting to note that an ex-Engesa employee recalls that the ET-25 turret was a manual turret. According to Jane’s Armour and Artillery, this seems to not be the case, as the ET-25 turret came standard with the electric turret drives. It is, however, possible that the employee referred to the prototype ET-25 turret instead, which does seem to have been a repurposed ET-90 II turret.
From here on, the timeline starts to get hazy. This mainly has to do with a single picture of the EE-9 with the new ET-25 turret being tested in Iraq with an Iraqi paint scheme. This hull could be the same hull as the one with the prototype ET-25, but an ex-Engesa employee remembered that the turret was tested on one of the Iraqi hulls. This last detail of the ex-Engesa employee may hold the potential clue in the timeline.
The ET-25 being tested on an Iraqi EE-9 M4 hull.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
The course of events seems to have gone as follows. An Iraqi commission visited the Engesa factory in September 1986. During this visit, led by Minister of Military Affairs General Abdul Jabbar Shanshal, the founder of Engesa, José Luiz Whitaker Ribeiro, showed the EE-9 ET-25 to the Iraqi general. The vehicle was presented in a brown and dark green camouflage with the EE-T1 P2 Osorio presented behind the vehicle.
The EE-9 with ET-25 being presented to Iraqi Minister of Military Affairs General Abdul Jabbar Shanshal (right) by Engesa founder José Luiz Whitaker Ribeiro (left).
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
After that, in February 1987, it was presented at the Engesa facilities to a Kuwaiti delegation. Why Kuwait was interested in the vehicle is unknown. The turret was dismounted from the hull but still retained the brown and dark green camouflage. Afterwards, the turret seems to have been sent to Iraq for final trials, where it was mounted on an EE-9 M4 hull from Iraq. It failed to garner enough interest and was sent back to Brazil.
The ET-25 turret presented to the Kuwaiti delegation.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
A 30 mm armed ET-25?
While researching the EE-9 ET-25, the writer found a number of mistakes in previous sourcing. The Italian turret was one of these, while the other error was a supposed 30 mm armed ET-25. According to Expedito Carlos Stephani Bastos, the new ET-25 turret was armed with a 30 mm gun. Multiple ex-Engesa employees refute this claim however, of which one was present when the delegation from Kuwait came to visit the turret.
In addition, the Jane’s Armour and Artillery book also presented the ET-25 turret and never mentioned an optional possibility to mount a 30 mm autocannon. This would be strange if the 30 mm was actually built as Engesa was known to offer as many options as possible to cater to potential customers. As such, it is very unlikely that a 30 mm armed ET-25 was ever built.
EE-9 ET-25 in Detail
As the EE-9 ET-25 was meant for Iraq and was actually mounted on an EE-9 M4 hull, the writer will write the technical section based on the EE-9 M4 specifications. This does not, however. mean that the ET-25 turret would have been exclusively offered on EE-9 M4 hulls.
The EE-9 ET-25 weighed around 12.5 tonnes (13.8 US tons) combat-loaded. It was an estimated 5.3 m (17.4 feet) long including the gun, as the muzzle brake seems to slightly extend further than the hull, and 5.25 m (17.2 feet) without the gun. It was 2.59 m (8.5 feet) wide, about 2.57 m (8.4 feet) tall to the top of the turret and about 3.2 m (10.5 feet) tall if the ET-50 .50 caliber machine gun mount was counted as well. The EE-9 ET-25 had a crew of three, consisting of the commander/loader (turret left), gunner (turret right), and the driver in the middle front hull.
A rear image of the EE-9 with the prototype ET-25 turret.
Source: Claudio Agostini
Hull
The hull of the EE-9 M4 was manufactured from welded bimetal steel plates. The hull also featured two covers which were mounted on the hull above the Boomerang suspension, effectively functioning as mudguards and very minor spaced armor. These mudguards could also have depressions in the middle, as on the Iraqi EE-9 M4s, to stow additional jerrycans.
The front upper hull plate presented 16 mm (0.63 inch) of bimetal armor at an angle of 60º. The sides and rear were 8.5 mm (0.33 inch) thick at varying angles, and the top and bottom hull were 6.5 mm (0.26 inch) thick. The front of the EE-9 was meant to protect from .50 machine gun fire at an unknown range, while the entire vehicle was protected from 7.62 mm AP rounds at 100 m (109 yards), and standard 7.62 mm rounds at 50 m (54 yards).
The average effectiveness of the bimetal plates was about 1.8 times the thickness of an equivalent homogeneous plate against 7.62 mm or 1.5 times the thickness against .50 machine gunfire. This meant that, against .50 machine gun fire, a 16 mm bimetal plate could be used instead of a 25 mm homogenous steel plate. These protection advantages over homogenous plates effectively meant that the Cascavel saved a lot of weight without compromising protection. The outer layer would shatter and blunt the incoming projectile, while the inner layer would relatively move with the bullet, slowing it down and stopping it without shattering.
The EE-9 M4 had two headlights and black-out lights integrated in both sides of the lower front plate. A rearview mirror could be mounted on both sides of the upper front plate. Below the driver’s vision block was a foldable windshield, which the driver could use when driving with an open hatch. The driver had access to 3 periscope sights mounted in a sort of vision block in front of him. The driver’s rotating sliding hatch was part of the top plate and was located behind the vision blocks. These periscopes and other periscopes or sights would not have been active or passive night vision equipment unless the Cascavel was ordered with these devices. The standard periscopes were manufactured by D.F. Vasconcellos.
A frontal view of a Colombian EE-9 M4 showing the headlights, the windscreen, and the 3 periscopes.
Source: Rodolfo Alberto Riascos Rodriguez
A ventilation inlet was installed on both upper hull side plates. These ventilation inlets are recognizable by their frustum shape. A siren was installed behind the ventilation inlet on the right side of the vehicle. The fuel tank cap of the Cascavel was located on the left side, in the middle of the upper side hull plate, with the fuel tank installed on the hull floor. The EE-9 had a large ventilation grille on the rear of the vehicle, reminiscent of the M8, and had a rear light on both sides of the ventilation grill. The engine could be accessed through two large hatches on the hull top rear. The engine exhaust was located on the top right rear plate, as was unique to the EE-9 M4s.
An interior sketch of an EE-9 M4.
Source: EE-9 M4 Manual
The M4 used an adjustable ZF 8062 hydraulic powered steering wheel and had two pedals: the throttle on the right side of the steering wheel, and the brake to the right of the throttle. The gear selector was located to the right of the driver and the hand brake was located to the left. A control panel was located on the front left of the driver for, among other things, the headlights, siren, windshield, the various meters, and interior lighting. To the right was the pressure selector for the central tyre inflation system.
Mobility
The EE-9 M4 used the Detroit Diesel 6V53N V6 engine which produced 212 hp at 2,800 rpm and 598 Nm at 1,800 rpm. The engine had a total cylinder capacity of 5.212 liters, with a cylinder diameter of 98 mm and a stroke of 114 mm. The M4 Cascavel had a top speed of 95-100 km/h (59 mph) and an operational range of 750 km (466 miles).
It had a turning radius of 8.12 m (8.88 yards) and it could ford a depth of 1 m (3.3 feet). The Cascavel could climb a 65º slope, could climb a vertical obstacle of 0.60 m (2 feet), cross a 1.65 m (5.4 feet) trench, and had a ground clearance of about 0.5 m (1.6 feet). The front-wheel could travel for 0.2 m (0.66 feet), while the rear wheels could travel for 0.9 m (3 feet). It used 12 X 20 run-flat tires with a diameter of 0.5 m (1.6 feet). The EE-9 M2 had a distance between the front axle and rear axle of 3.05 m (10 feet), and a distance of 1.4 m (4.6 feet) between the two rear wheels.
The EE-9 M4 used an automatic Detroit Allison MT-643 transmission with four forward and one reverse gears. The transmission system could handle up to 250 hp and was the only transmission used in the EE-9s which could mount the Detroit 6V53 engine. The M7s would also use this transmission, but they were never paired with a Detroit when they were sold by Engesa.
In addition, the Cascavel used an Engesa 2 speed transfer case, which allowed the Cascavel to be used in reduced and high gear. By putting the Cascavel in reduced gear, horsepower was sacrificed for increased torque, making it more effective in climbing slopes. The vehicle was 6 x 6 driven, of which the rear 4 wheels were part of the Boomerang suspension. The Boomerang suspension, in combination with the Engesa 2 speed transfer case, enabled the Cascavel to cross challenging terrain and provide maximum traction in most situations.
The drivetrain of an EE-9.
Source: Engesa Manual
The power of the engine was distributed to a differential on the front side of the vehicle, and a differential in the rear. The rear differential drove the Boomerang suspension with a single axle, which made the Boomerang suspension such an ingenious design.
In 1969, this suspension was invented by Engesa to enable trucks to transport oil to the refineries through rough terrain with bad infrastructure. With this suspension, the trucks could traverse otherwise untraversable hills for conventional suspension systems, as the wheels would always stay in contact with the ground to provide maximum traction.
The suspension system was a two wheeled-single axle driven suspension. The advantage of the Boomerang suspension was that it could be fitted on existing differentials with a single axle. Normally, this meant that the single axle, designed for the torsion forces of a single wheel, was subjected to the torsion forces of two wheels. Through excellent engineering, half of the torsion forces of the two wheels were mitigated by the suspension system built around the original axle. This design not only enabled the drive of two wheels by a single axle but, with clever usage of gears and bearings on both the axle and tube around the axle, the suspension system can rotate around its axle for 360º. This ability to rotate in extreme angles would enable the vehicles to traverse very difficult terrains and still provide maximum traction, as the suspension system curved with the terrain so that all the wheels were always in contact with the ground.
Exploded view of a Boomerang suspension.
Source: Engesa Manual
The Boomerang suspension used leaf springs for dampening. The two front wheels were used for steering. The wheels on the Boomerang suspension all rotated at the same speed. The front wheels were dampened by large coil springs. The vehicle used hydraulic disc brakes, and was steered with hydraulics as well.
A Central Tyre Inflation System (CTIS) came standard with the M4s. This system would help in obtaining the appropriate traction at various speeds by regulating the tyre pressure. This could help in crossing rough terrain but also save fuel. This was done by the driver through a switch. A Bendix Tu-flo 500 air compressor was used to provide the air flow and pressure for the CTIS.
Turret
The EE-9 ET-25 used an all-welded bi-metal steel construction to protect against small arms fire. The armor layout of the ET-25 is unknown, but considering the weight of the turret, it would quite likely be similar to that of the ET-90 II turret. This would mean that the ET-25 would have had 16 mm of bimetal armor at the front and 8 mm at the side, rear and top. This would make sense since the hull had a similar armor layout.
The turret front had a wedge shape with the 25 mm KBA autocannon in the gun mount being located in the middle. A coaxial 7.62 mm machine gun was located to the left of the turret in a separate mounting system which seemed to be slaved to the elevation of the main armament. Two lifting hooks were attached to the front side plates, one on each side of the turret. A main armament slaved search light was mounted on the left front side of the turret and a spent shell case ejection system was located in a depression on the right front side of the turret. The shell election system was further protected by two steel covers. The turret had three electrically operated 81 mm smoke dischargers on each side of the rear side plates.
A side view of the turret, note the two folding covers over the shell case ejection system.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020
The commander was located on the left side of the turret and had access to a raised cupola. The cupola was able to receive the ET-50 .50 machine gun mount as well for the commander and had a rear-opening hinge hatch. The commander had access to an unknown 3x day periscope which could be replaced by a 2.7x magnification night periscope. In addition, the commander had access to four 1x magnification periscopes located circularly around the hatch.
The gunner was located on the right and had access to a day/night sight as the main gun sight. The sight type is unspecified, but considering Engesa and Iraq widely used the SS-122 sight on the Cascavels and considering the magnification levels listed, it is quite likely the ET-25 uses an SS-122 sight. The SS-122 sight was an image intensifier sight which provided 10x magnification for the day sight and 9x for the passive night vision channel. The sight mirrors were coupled to the main armament to allow for automatic elevation of the sight mirrors in accordance with the gun elevation.
The SS-122 gunner’s sight.
Source: Jane’s Armour and Artillery
On the ET-25, the sight used an integrated laser rangefinder and offered graticules for air engagements. The turret did not seem to have utilized the SS-123FC fire-control system however, as the turret description does not mention the turret having access to a system providing a moving aiming mark for the sights. As such, target engagement would have had to be done through manual operation of the turret drives and the necessary lead caused by moving helicopters would have had to be estimated by the gunner. This effectively meant that, while the EE-9 ET-25 was to serve as practically the last line of defense of a convoy, it did not have all the potential tools at its disposal to somewhat reliably engage fast moving helicopters.
The turret used an electrically powered traverse and elevation system which was powered by the gunner’s controls. This enabled the ET-25 turret to have a turret traverse speed of 36°/s and an elevation speed of 21°/s. The turret offered a gun depression of -10° and an elevation of +55°. It had a 1.6 m turret diameter, which was the same as the other EE-9 turrets, and had a 0.63 m penetration depth within the hull.
Armament
The EE-9 with ET-25 was armed with an Oerlikon 25 mm KBA autocannon. The 25 mm KBA had a total length of 2,888 mm and a barrel length including muzzle brake of 2,173 mm. It had a recoil stroke of 25 to 34 mm and weighed 112 kg in total. The KBA used a double belt feed, allowing for two types of ammunition to be fired and offered multiple firing modes. It could fire in single shot, programmable rapid single shot with a rate of fire of up to 200 rounds per minute and fully automatic with a rate of fire of 600 rounds per minute. The gun was described by an ex-Engesa employee as a work of engineering art.
The 25 mm KBA has seen service on a wide array of vehicles including infantry fighting vehicles, reconnaissance vehicles, armored personnel carriers, and anti-aircraft vehicles. Most autocannon based anti-aircraft vehicles used at least multiple cannons and had some form of fire-control system to help track air targets, two things which the ET-25 did not have. In addition, practically all other uses with a single autocannon were on reconnaissance vehicles or infantry fighting vehicles where engaging air targets was a secondary mission, not the main objective, as with the EE-9 ET-25.
The ET-25 had 325 ready-use rounds for the 25 mm autocannon, of which 190 would have been High-Explosive Incendiary rounds and 135 would have been Armor-Piercing Discarding-Sabot ammunition. The latter could penetrate up to 25 mm of steel at 2,000 m at an inclination of 30°. It had an effective firing range of 3,020 m and a maximum firing range of 5,850 m. The APDS ammunition would reach a target at 2,000 m in 1.7 s and the HEI in 3.3 s.
In addition, the ET-25 had 200 ready use rounds for the coaxial 7.62 model F-1 machine gun. It supposedly also had 200 rounds in reserve, which would be somewhat strange, as the standard ET-90 turrets had 2,000 rounds in reserve for the coaxial machine gun, which seems a more likely value. In addition, a .50 machine gun could be mounted, which would likely entail that some 7.62 ammunition boxes would have had to be swapped out for .50 boxes instead. The amount of reserve 25 mm ammunition the EE-9 ET-25 carried is unknown.
Fate
In the end, the EE-9 with ET-25 turret failed to get any sales. After testing, Iraq returned the turret to Engesa, where it was supposedly scrapped. The EE-9 ET-25 concept seemed to have mainly suffered from the flaw of being everything and nothing. While the 25 mm KBA was used for anti-aircraft purposes on vehicles, autocannon armed anti-aircraft vehicles usually had multiple autocannons and a fire-control system to help engage the air targets. The ET-25 had neither of these and was already lacking in acting as an anti-aircraft vehicle, especially as a last line of defense. In addition, an ex-Engesa employee recalled the tendency of the Iraqis to make widespread use of heavy machine guns to achieve somewhat similar results.
In addition, vehicles that did use a single 25 mm autocannon were usually either reconnaissance vehicles or infantry fighting vehicles. This issue with using the EE-9 ET-25 as a reconnaissance vehicle was that it was a more expensive 90 mm armed EE-9 which also served as a reconnaissance vehicle.
The autocannon alone was already about US$100,000 in 1988 compared to the US$60,000 for the 90 mm gun. In addition, the turret structure itself was also US$5,000 more expensive than a standard ET-90 turret (US$45,000 compared to US$40,000). Had the buyer requested the turret drives to be installed as well, the turret price would have increased with an additional US$58,000. This would have made a fully outfitted EE-9 ET-25, which would have been somewhat capable of fighting off helicopters, cost about US$361,000 compared to the standard Cascavel at US$258,000 without turret drives.
With regards to serving as an infantry fighting vehicle, the Brazilian Army had already identified in the mid-1970s that the EE-9 Cascavel would be unfit for such use due to its lack of armor. Additionally, it could not transport troops either, turning it into either a fire support vehicle or reconnaissance vehicle. The EE-9 ET-25 would have been outclassed by the more cost-effective 90 mm armed EE-9 in both roles.
Additionally, from 1987 onwards and even before, financial war fatigue had reached the Iraqi government. After 7 years of fighting, stalemate, and being the largest arms importer throughout this period, the Iraqi coffers had started to run dry. In its quest to find new and more arms to tip the scales in its favor, the Iraqi government proceeded spending itself into potential bankruptcy. Among the arms to be bought by the Iraqis were for example Astros 2 rocket ammunition, which ended up being stockpiled by Avibras to then be sold to Saudi Arabia in 1991 and used against Iraq in the Gulf War. It is quite likely that Iraq simply could not afford such a specialized and seemingly not very effective vehicle like the EE-9 ET-25.
Conclusion
The EE-9 ET-25 turned out to be the only EE-9 to receive a different main gun than the original 90 mm gun by Engesa or the initial 37 mm. But for all the goals, it seemed to have failed in actually delivering on those promises. It was a jack-of-all trades vehicle with all the shortcomings a jack-of-all trades tends entail. It lacked the ammunition volume and fire control system to serve as an effective anti-aircraft vehicle, the cost-effectiveness to serve as a reconnaissance vehicle, and the armor and infantry carrying capability to serve as an infantry fighting vehicle.
Why exactly the Iraqis did not decide to buy the vehicle is unknown, but it is a possibility that the Iraqi staff had also recognized these flaws. In addition, Iraq simply could not afford the armament which it once could anymore. In short, the EE-9 ET-25 was, for all intents and purposes, a failure in both concept and sales.
The EE-9 testbed carrying the prototype ET-25 turret in April 1985. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.EE-9 M4 Cascavel armed mounting the ET-25 turret. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.The EE-9 M4 with the prototype ET-25 turret in July 1985. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.
Specifications (EE-9 M4 ET-25)
Dimensions (L-W-H)
5.3 (with gun) x 2.59 x 2.57 m (17.4 feet x 8.5 feet x 8.4 feet)
Total weight
12.5 tonnes (13.8 US tons)
Crew
3 (Driver, commander, gunner)
Propulsion
Detroit Diesel 6V53 212 hp engine (or OM352A 172 hp engine)
Speed (road)
95-100 km/h (59 mph)
Operational range
750 km (466 miles)
Armament
25 mm KBA autocannon
7.62 mm N model F-1 (coaxial)
Optional .50 machine gun (turret top)
Armor
Hull Bimetal
Front 16 mm (0.63 inch)
Side 8 mm (0.32 inch)
Rear 8 mm (0.32 inch)
Top 6.5 mm (0.26 inch)
Floor 6.5 mm (0.26 inch)
ET-25 turret (Estimated)
Front 16 mm (0.63 inch)
Side 8 mm (0.32 inch)
Rear 8 mm (0.32 inch)
Top 8 mm (0.32 inch)
Produced
1
Special thanks to Expedito Carlos Stephani Bastos, the leading expert of Brazilian armored vehicles https://ecsbdefesa.com.br/, Jose Antonio Valls, an Ex-Engesa employee and expert in Engesa vehicles, Paulo Bastos, another leading expert of Brazilian Armored vehicles and the author of the book on Brazilian Stuarts and the website https://tecnodefesa.com.br, Adriano Santiago Garcia, a Captain in the Brazilian Army and ex-company commander on the Leopard 1 and ex-lecturer on the Brazilian Armored School, and Guilherme Travassus Silva, a Brazilian with whom I was able to endlessly discuss Brazilian Vehicles and who was always willing to listen to my near endless ability to talk about them.
Sources
Engesa EE-9 Cascavel 40 anos de combates 1977-2017 – Expedito Carlos Stephani Bastos
Brazilian Engesa EE-9 Cascavel 6×6 at war 1977-2020 – Expedito Carlos Stephani Bastos
Blindados no Brasil – Expedito Carlos Stephani Bastos
Engesa manuals
Engesa brochures
Dual Harness skin stops armor-piercing projectiles Article of Richard M. Ogórkiewicz
Personal correspondence with Ex-Engesa Employees
Personal correspondence with Expedito Carlos Stephani Bastos
Personal correspondence with Paulo Roberto Bastos Jr.
Personal correspondence with Adriano Santiago Garcia
EE-9 with ET-90 turret. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.
Federative Republic of Brazil (1974)
Wheeled Reconnaissance Vehicle – 464 Built (M2), 200 Built (M3)
While the EE-9 was still in its pre-production stage, known as the CRM, the Brazilian Army considered arming their new wheeled reconnaissance vehicle with a 90 mm gun in 1972. The 90 mm gun would not only make the Cascavel more capable to fight potential enemies during reconnaissance, it also made the vehicle more appealing for export. Sadly, the debate on how to arm the EE-9 raged for most of the 1970s and it would be foreign countries which gave the needed nudge for the 90 mm armed Cascavel to be created.
While building the pre-production vehicles, Engesa trialed the EE-9 in Portugal in 1973. Portugal was impressed with the platform, but did not like the 37 mm cannon with which all the Cascavel prototypes were armed up to that point. The Portuguese suggested rearming the platform with the gun and turret combination of the French Panhard AML-90, known as the H-90 turret. Engesa built a 90 mm armed version and then returned for trials in early 1974. The legendary 90 mm armed EE-9 Cascavel was born, and with it, Engesa’s most successful armored fighting vehicle entered the world stage of wheeled reconnaissance vehicles.
The EE-9 M2.
Source: Rodolfo Alberto Riascos Rodriguez
The Road to the EE-9
The first steps towards the EE-9 Cascavel were taken in 1967 with the creation of the Parque Regional de Motomecanização da 2a Região Militar (PqRMM/2, English: Regional Motomecanization Park of the 2nd Military Region). The PqRMM/2 was a group of army automotive engineers gathered to study, develop and produce armored vehicles in Brazil, and were the pioneers of the Brazilian defense industry.
They began with an engine replacement program for the M8 Greyhound and the M2 half-track with diesel engines. With the success of these projects, they continued to the next phase of the program and developed Brazil’s first wheeled vehicle with serial production in mind. The Viatura Blindada Brasileira 1 (VBB-1) (English: Armored Car of Brazil 1) was a 4 x 4 vehicle meant for reconnaissance and mounted a copy of the M8 Greyhound’s turret.
The VBB-1, note the influence of the M8 Greyhound on aspects such as the turret.
Source: Blindados no Brasil
Although the VBB-1 seems to have successfully performed its tests when the vehicle was presented to the Army in 1969, the Army did not want a 4 x 4. It was briefly considered by the engineers to cut the hull in half and lengthen it to accommodate a 6 x 6 suspension, but the idea was almost immediately rejected, as the development of a new vehicle was deemed more effective.
The first mock-up of the new 6×6 was known as the Viatura Blindada de Reconhecimento 2 (VBR-2, English: Armored Reconnaissance Vehicle 2). The VBR-2 was pretty much a Brazilian copy of the M8 Greyhound and it was armed with a 37 mm cannon and a .50 cal machine gun. A single metal mock-up of the VBR-2 was made by the PqRMM/2 in early 1970.
The VBR-2 mock-up underwent various redesigns together with a redesignation to Carro de Reconhecimento sobre Rodas (CRR) (English: Wheeled Reconnaissance vehicle). The hull underwent some geometric redesigning compared to the VBR-2, causing the vehicle to look less like a box because of the more angled side plates. Another difference in the hull design, which enabled the hull to receive an improved ergonomic design, was the redesign of the driver’s raised hull construction.
Another important step in the development of the CRR was the installation of the Boomerang suspension from Engenheiros Especializados SA, better known as Engesa. Engesa had previously modernized and delivered new trucks for the Brazilian Army with their Total Traction system. This patented traction system was the key for Engesa in the defense industry, mainly because it was identified as a system ‘of interest to National Security’ by the Army. Engesa also participated in the VBB-1 project by supplying the transfer box.
With the installation of the Boomerang suspension and the redesign of the hull, the basis was laid for what would become the EE-9 Cascavel. The mock-up of the CRR was built in early 1970 and presented to General Plínio Pitaluga, a veteran of the FEB (Força Expedicionária Brasileira, Brazilian Expeditionary Force). It seems that, almost immediately after the mock-up was finished, the PqRMM/2 engineers started the production of the first working prototype. The prototype of the CRR was completed in 1971. It used a copied and redesigned M8 turret, armed with a 37 mm cannon and a .50 machine gun on the roof. The turret was fully enclosed. The vehicle-mounted run-flat tires had previously been developed by Novatracão for the VBB-1 project.
The CRR, note the M8 copied turret and the Boomerang suspension.
Source: Engesa brochure
The CRR was extensively tested by the Brazilian Army and overseen by the PqRMM/2. The tests were successful, as the construction of a 5 vehicle pre-series was approved. This increased to 8 vehicles after the Diretoria de Pesquisa e Ensino Técnico do Exército (DPET) (English: Army Directorate of Research and Technical Education), which oversaw the PqRMM/2 developments, signed a contract with Engesa in June 1971 for the development and construction of the pre-series. Production began in 1972 and was finalized in September 1975.
With the signing of this contract, the CRR was officially carried over to Engesa. What is interesting is that the Brazilian Army, despite having developed the CRR, signed off all their intellectual property rights to Engesa. This effectively meant that the Brazilian Army itself would not directly profit from any sales of the future EE-9 Cascavel to other countries. This transfer to Engesa also meant that the CRR would be marketed as the EE-9 Cascavel.
Engesa
Engenheiros Especializados SA, or Engesa, was the largest and the most famous company in the Brazilian armored vehicle industry. Engesa was founded in São Paulo in 1958 by José Luiz Whitaker Ribeiro. Initially, Engesa focused on oil prospecting, production, and refinement equipment. With the invention of Engesa’s Total Traction suspension system, they were hired to modernize and build trucks for the Brazilian Army.
In 1969, Engesa introduced its flagship Boomerang suspension for its wheeled vehicles. Only a single axle was needed to drive the 4 wheels which were in continuous contact with the ground, providing constant traction. At the time, this was a simple, sturdy, and relatively cheap construction. Although not fit for heavy vehicles, it was perfect for the armored vehicles that Engesa would start to manufacture in the near future.
With Engesa’s involvement in refitting the Army’s trucks with the Total Traction system and the development of their Boomerang suspension, they were contacted by the Army to help develop the wheeled vehicles together with the PqRMM/2 team. This joint development resulted in the EE-9 Cascavel and the EE-11 Urutu. The EE-9 Cascavel paved the way for Engesa to take its position as the leading company of the Brazilian defense industry.
The EE-9 Cascavel was part of a family of wheeled vehicles, all named after snakes found in Brazil. These vehicles were the EE-3 Jararaca, EE-9 Cascavel, EE-11 Urutu, and EE-17/18 Sucuri, meaning jararaca, rattlesnake, crossed pit viper, and anaconda, respectively.
The EE-3 was a 4 x 4 reconnaissance vehicle which could mount a wide range of turrets. The EE-9 was also a reconnaissance vehicle, but due to its mobility and the 90 mm cannon, it would be employed in all kinds of roles. The EE-11 was a troop transport, but could be configured to perform all sorts of specialized roles, such as anti-aircraft, mortar carrier, and ambulance. The EE-17 and EE-18 Sucuri were two 105 mm armed 6 x 6 wheeled tank destroyers.
Logos of Engesa’s Snake family.
Source: Blindados no Brasil – Expedito Carlos Stephani Bastos
The EE-9 was effectively the flagship of this family, even though Engesa thought the EE-11 would be their most successful vehicle. The EE-11 was successful nevertheless, but the Jararaca and the Sucuri were less of a success. The Jararaca was sold in very limited numbers, while the Sucuri was not even sold at all.
With the transfer of the CRR to Engesa also came a new designation. The exact date of when the CRR was designated as EE-9 is unknown. But it is estimated to have been renamed between 1972 and 1973, with EE referring to Engenheiros Especializados (English: Specialized Engineers) and the 9 to its weight in tonnes. The interesting part is that practically every Cascavel exported by Engesa weighed more than 10 tonnes empty. As such, the 9 in EE-9 refers to the 37 mm version of the Cascavel. The weight in a brochure, which is estimated to have been written between 1973 and 1974, refers to the Cascavel with a 37 mm gun as having a 9 tonnes combat weight.
The CRR was redesignated by the Army as well, with the completion of the pre-production batch, to Carro de Reconhecimento Médio (CRM) (English: Medium Reconnaissance Car). This designation is more of a vehicle classification, like the CRR, than a name. This effectively means that the prototype CRR, the pre-production CRM, and the production vehicles were all known and sold as EE-9s.
What is interesting is that Engesa seems to have skipped designating an M1 Cascavel and immediately built M2 hulls after the CRM. It might be that the 37 mm Cascavels were unofficially seen as first production versions, but through hull classification were simply branded as M2s.
Since the EE-9 Cascavel was built and developed for 18 years, it received upgrades and design changes over time. To keep track of these changes, a so-called Modelo or Model system was used. It is important to note that different guns or turrets did not determine a different Cascavel model. The Cascavel M2 for example, used two 90 mm turrets offered by Engesa (HS-90 turret with the French D-921 gun and the ET-90 I turret with EC-90 gun). It was mainly changes to the hull, and especially the transmissions, which caused the Cascavels (Portuguese: Cascavéis) to be classified as a certain model. The Modelos were then further subdivided in production batches or Séries. The differences between the series could be as small as different bolts or different tyre nozzles. The development of the Cascavel was an evolutionary process, and certain manuals would be written specifically for a range of series of a certain model.
The enthusiast’s guide to Engesa’s Cascavel galaxy
Model
Characteristics
Date
Number sold by Engesa
CRM
The pre-production EE-9 with a manual Clark 280V transmission and a 37 mm gun, practically an improved M8 Greyhound.
1971
8
EE-9 M2
Interestingly, Engesa seems to have skipped designating a Cascavel with the M1 designation. As a result, the production Cascavels with 37 mm guns are also M2’s.
The first EE-9 to have a 90 mm gun as its main armament. Overall hull redesign, larger dimensions of the hull to mount the new 90 mm armed turrets. Used a manual Clark 280V Transmission
1974
Brazil: 157 of which at least 9 were originally armed with 37 mm.
Bolivia: 24
Chile: 83
Libya: 200
EE-9 M3
Effectively an M2 Cascavel, but with an automatic MT-540 transmission (the first Cascavel model with an automatic transmission). The first Cascavel model to receive the EC-90 gun.
1975
Libya: 200
EE-9 M4
The M4 was specifically designed, built and sold with the Detroit Diesel 6V53 engine. Overall strengthening of components and further evolution of the hull design. It used an MT-643 transmission.
1979
Brazil (CFN): 6
Colombia: 128
Cyprus: 124
Iraq: 364
EE-9 M5
Used the M4 design but was a cheaper version. It was sold with either an AT-540 or AT-545 transmission in combination with the OM-352A engine.
1981
Bovington Tank Museum: 1
Gabon: 14
Uruguay: 15
EE-9 M6
Automotive enhancements over the previous models. Used the AT-545 in combination with the OM-352A engine.
1982
Brazil: 37
EE-9 M7
The same as the M6, but used an MT643 transmission. This Cascavel was the final model designed by Engesa. It could mount every engine which Engesa sold with the Cascavel, although it only seems to have been used with the OM-352 and the OM352A engines.
Total: around 1,742 sold and less than 1,800 produced.
Arming the EE-9 Cascavel
In 1972, with the start of the construction of the pre-production Cascavels, came the discussion of what the future reconnaissance vehicles of the Brazilian Army should be armed with. Up until then, reconnaissance doctrine of the Brazilian Army had not changed since their experiences in World War 2, and this old doctrine was still somewhat ingrained in the Army.
An analysis regarding the specifications for a reconnaissance vehicle was released on July 10th 1967. The requirements called for a vehicle which could penetrate its own armor at ranges up to 1,000 m, fire in all directions (have a turret), a rate of fire of at least 3 shots per minute, and the armament did not have to be used for anti-aircraft purposes. The issue with these requirements was that practically every gun of 20 mm and larger could perform this job.
With the initiation of the VBR-2 project, a discussion emerged within the Army. Recommendations were gathered on what to arm the coming generation of reconnaissance vehicles with. The issue was that the Armies (plural) of Brazil, generals, and departments gave conflicting advice. Aside from this, the Army also had to take export potential into consideration for Engesa. Since the Brazilian Army completely handed over the project to Engesa, they also wanted to keep logistics and profit for the company as advantageous as possible. By the end of 1972, the Brazilian Army had selected two ranges of potential cannons: 20 to 40 mm or the 90 mm. The Army referred to the FV107 Scimitar for the lower caliber cannons, potentially suggesting that they wanted an autocannon on the Cascavel, and not the 37 mm which they had used so far.
With the selection of the two ranges, a new discussion came at the forefront regarding the purpose of the reconnaissance vehicle. It was recognised that less than 4% of the missions performed by cavalry units during World War 2 were pure reconnaissance missions. The question then was which role would the future Cascavel perform the most and which of these guns was the most suitable. The 90 mm would perform best for anti-tank missions, while the 20 to 40 mm range would be more fit against personnel and overall perform an infantry fighting vehicle role, without being able to carry infantry. It was identified that the EE-9 would not be fit to fill the Infantry Fighting Vehicle (IFV) role as it lacked the needed armor. At the same time, it was recognised that a 90 mm gun would give the Cascavel a better fighting chance against potential enemy armor. The reasoning came mainly from an isolation point of view, in which a Cascavel on a reconnaissance mission had to fend for itself and take out potential enemies, such as tanks. It was determined that the 90 mm was the most suited for this role, considering most of Brazil’s neighbors operated the Shermans as their heaviest armored vehicles at the time, and employed a large number of light AMX-13s and SK-105s as their other combat tank.
It took up to the second half of the 1970s for the Brazilian Army to completely make up its mind on which cannons should be used on the Cascavel. When this discussion still raged in 1977, the Cascavel with 90 mm gun was already used by Libya against Egypt, and multiple countries ordered the 90 mm cannon. What might have steered the Brazilians towards eventually deciding to solely operate a 90 mm Cascavel force were the trials in Portugal in 1973.
Armoring the EE-9 Cascavel
Until 1968, armor studies were practically non-existent in Brazil. There had been some brief attempts during the revolutions of 1924, 1930, and 1932, but these were mainly of improvised nature. With the initiation of national armored vehicle development also came studies on what to armor the upcoming armored vehicles with. The PqRMM/2 team started off by evaluating all the steel compositions of the vehicles which were acquired by the Brazilian Army over time. The team discovered that the homogenous steel plate of the M2 Half-Track had been heat-treated on the outer side to provide a harder surface, while providing a more ductile surface on the inside to prevent shattering.
The team determined that the effort needed to carry out the necessary techniques for hardening was only justifiable for mass production. With mass production of the future armored vehicles being expected, the team decided that the development of a dual-hardness plate or bimetal armor would be viable. This type of steel was previously developed in Sweden in 1930 and was known as duplex steel. It would find its first extensive usage on armored vehicles in Brazil. The main difference from other examples of face hardened armor is that two plates of varying carbon content were welded together in production to form a bimetal plate instead of bolting on a hardened plate afterward.
The steel for the bimetal plates was provided by Eletrometal and Usiminas. With Eletrometal providing the high-carbon outer plates and Usiminas the medium-carbon plates. The plates were joined, with 25% of the total plate thickness being high-carbon steel and 75% medium-carbon. The plates were laid on top of each other and subsequently welded around the edges. The bimetal plates were then forged together from 65 mm to about 30 mm thickness and then hot-rolled to the required thickness. This was followed by a quench, tempering, and hardening to the desired hardness. The high-carbon plate was hardened to 700 Brinell while the medium-carbon plate was 250 Brinell.
The average effectiveness of the bimetal plates was about 1.8 times the thickness of an equivalent homogeneous plate against 7.62 mm or 1.5 times the thickness against .50 machine gunfire. This meant that, against .50 machine gun fire, a 16 mm bimetal plate could be used instead of a 25 mm homogenous steel plate. These protection advantages over homogenous plates effectively meant that the Cascavel saved a lot of weight without compromising protection. The outer layer would shatter and blunt the incoming projectile, while the inner layer would relatively move with the bullet, slowing it down and stopping it without shattering.
An interesting tidbit of information according to an ex-Engesa employee who worked at the tempering station was that, at some point, the armor did not perform according to standards. It turned out that the tempering oven was not maintained properly, and the temperature control was faulty. This issue would remain for a few years until it was finally resolved. In order to keep building the armored vehicles, a lot of these plates were approved by quality check anyway, despite being faulty.
From Former Colony to Colonizer to Former Colony
In early 1973, Engesa trialed their vehicle in Portugal in an attempt to export them. Portugal was fighting uprisings in its colonies in the War of Ultramar, also known as the Overseas War in English. At the time, the Portuguese Army was operating a mix of AML-90 and Panhard EBR armored cars in Africa.
The Portuguese were impressed by the EE-9 Cascavel, which at that time was most likely still in its CRR configuration, but they suggested that Engesa should arm the Cascavel with the same turret and gun as the AML-90 and return to trial the vehicle again. The platform of the EE-9 was good, but its 37 mm armament was outdated and not competitive with what Portugal already had.
With Engesa wanting to arm the Cascavel with a 90 mm gun, the Brazilian Army opted to go for the 90 mm gun on the X1 project as well. They bought 53 turrets and guns from the French company SOFMA. Most of these turrets were ditched by the X1 program, as they did not meet the protection requirements of the Brazilian Army, and local turrets were designed (based on the HS-90 turret of the AML-90) and built as a result. The reason why the Brazilians did not just buy the guns if they were going to ditch the turrets anyway, was because the French company SOFMA refused to sell the gun independently from the turret. Engesa would arm the EE-9 sent to Portugal with the French turret, but also developed their own turret.
The EE-9 in Portugal was trialed again in early 1974 together with an EE-11 Urutu. The EE-9 probably had the eventual production variant hull design to solve some practical issues of the CRR and CRM configuration and mounted an HS-90 turret,armed with a D-921 90 mm gun. This EE-9 trialed in Portugal could be officially counted as being the first EE-9 M2 Cascavel with a 90 mm gun. But so far, no pictures have been found of the Portuguese trials to definitively prove which exact prototype was sent and how it looked.
The problem is that a number of designs were made before pictures of the actual production variant of the EE-9 appear. For this reason, it is uncertain what the exact vehicle looked like, although Paulo Bastos, the Brazilian author and leading expert in the field, stated it was the EE-9 M2 with 90 mm production version. Portugal would not acquire the EE-9 M2 because of a coup d’etat in the country on April 25th 1974, which also put an end to the War of Ultramar.
The influence of Portugal in the success of the EE-9 should not be understated. After the failed attempt to sell the EE-9 Cascavel to the Portuguese, the Engesa team loaded the Cascavel and Urutu back in their freighter and set course to Libya. There, the EE-9 M2 would find success and manage to secure a deal for 200 Cascavels. This deal brought the necessary cash for Engesa to buy a large production plant, and by 1975, the first production Cascavels started rolling from the production line. In 4 years, Engesa had sold the EE-9 M2 and M3 with the 90 mm gun to 4 countries, including Brazil, for a total number of 655 Cascavels.
The request of the Portuguese to arm the EE-9 with a 90 mm gun effectively helped Engesa to secure a deal with Libya, which used the Cascavel in combat, generating more sales and making the Cascavel the success it was. At the same time, Brazil also started the development of locally produced turrets for the 90 mm guns for both the Cascavel and X1.
The 90 mm Turret Designs on the EE-9 and Prototype Hulls
The switch from 37 mm towards the 90 mm would normally mean that the EE-9 Cascavel is an EE-9 M2. A number of projects however, were specifically designed on the early CRR hull or on a hybrid between the CRR and the pre-production vehicle which would be designated as Carro de Reconhecimento Médio (CRM, English: Medium Reconnaissance Car). The problem is that these designs were made before the production vehicle of the EE-9 was built. For this reason, these projects will be seen as prototypes for the EE-9 M2. There were two designs: a CRR/CRM hybrid mounting the copied and lengthened M8 turret and armed with a 90 mm gun and a CRR with the French turret. These designs are thought to have been made after early 1973 and before early 1974. This is because the brochure shows both designs while not showing an actual built Cascavel with 90 mm gun.
The CRR with HS-90 turret
The Brazilians made a design with the CRR hull mounting an HS-90 turret. This design was effectively the predecessor of the EE-9 M2 Cascavel. The HS-90 turret was ordered from France and had to be bought as a full package, including the D-921 gun. This Cascavel would have had a gun depression of 8º and an elevation of 15º. Aside from the 90 mm gun, it was also armed with a coaxial 7.62 mm machine gun and 3 smoke launchers on each rear side of the turret. It could mount a turret top machine gun, night vision sights, radio and intercom, laser rangefinder, and an extra ammunition stowage as optional equipment. It is stated that the EE-9 sent to Portugal used this turret, but it is unlikely that the CRR hull was used for these trials.
The CRR with a HS-90 turret.
Source: Engesa brochure
The reason for this is that the HS-90 turret would not only be too big for the hull and come in collision with both the driver’s vision structure, but also with the engine bay covers. On top of that, the driver’s vision structure would make it virtually impossible to depress or even fire the gun on a flat angle. As such, it seems that the drive for the 90 mm turret caused the hull to be redesigned to resolve these issues.
A sketch detailing the collision issues of the HS-90 turret on the CRR hull.
Done by Godzilla.
The CRR/CRM Hybrid with M8 Copy Turret
Another of the designs was effectively a hybrid between the CRR and the later CRM production vehicle. The main hull design change which hints towards it being a hybrid design is the altered headlight guard. On the CRR, the headlight guard was a simple square design, while in this design, it was curved, like on the CRM.
In addition, the copied M8 turret also received some changes which would be seen in the turret later used on the pre-production CRM. Compared to the original CRR turret, this turret had a ventilation inlet on the top of the turret and the antenna, which was originally on the left rear side of the hull, had now been installed on the turret as well. Apart from these 2 features, the turret also provided periscopes for the gunner, apart from the direct sight in the gun mantlet. The 90 mm gun would have a depression of 8º and an elevation of 13º and be installed in a turret with a turret diameter of 1.6 m. It could mount a turret-top machine gun for anti-aircraft purposes.
In addition, a Perkins type 6357 6 cylinders in-line 142 hp diesel engine, along with a Chrysler type 318 HD V8 196 hp diesel engine, were offered. Engesa also offered to fit in other engines, depending on the customer’s needs. It would use a 6-speed manual gearbox with five forward and one reverse speeds. It would have been protected from the front with bimetal armor, protecting against .50 machine gun fire and from the sides from 7.62 mm fire. The exact weight and speed of this design are unknown but are estimated at around 10 to 11 tonnes and 95 km/h, depending on the engine selected.
The CRR with the redesigned M8 turret, armed with a D-921 90 mm gun.
Source: Engesa brochure
The CRM and a Bid for a National Turret
By September 1975, the production of the pre-series of 8 vehicles armed with 37 mm cannons, known as the CRM, was finished. The pre-series hulls still carried over much of the design of the CRR hulls. The CRM can be easily identified and distinguished from the CRR in two ways. The first is the redesigned headlight guards, which were now curved instead of simple squares. The second is the relocation of the antenna and most likely the radio set as well. On the CRR, the antenna was located on the left rear of the hull, while on the CRM, the antenna was moved to the turret.
The CRR on the left with the simple square headlight guards and the antenna on the hull, and the CRM on the right with the redesigned headlight guards and without an antenna on the hull.
Source: https://pt.wikipedia.org/wiki/EE-9_Cascavel#/media/Ficheiro:Cascavel1.jpg and Ford M-8 Greyhound no Exército Brasileiro – Expedito Carlos Stephani Bastos
What makes the CRM complicated with the timeline of the EE-9 M2 with 90 mm gun, is that the CRM still used a number of design features from the CRR which would have made mounting a HS-90 turret practically impossible. It still used the raised driver structure, an external exhaust, and similar engine bay designs. What is thought to have happened is that the design and production of the pre-production batch was already well underway during late 1973 and early 1974, which would cause Engesa and the Army not to change the design of the pre-production vehicles. In addition, the Army had not yet finalized its stance towards the 90 mm gun, so a redesign might not even have been needed at that point.
Another important reason might be that the pre-production design was meant to be the final hull design for the EE-9. This is partially supported by a program in Brazil for a new national turret for the EE-9 for which both Engesa and Bernardini (the manufacturer of the X1 light tank) put forward their designs for the new turret. These turrets are for all intents and purposes the same as the turrets of the X1, with Engesa proposing the X1 turret of the first X1 prototype, and Benardini proposing the X1 production turret, but armed with a 37 mm. These turret designs were of a higher profile than the Hs-90 turret and with these turrets, the 90 mm could depress without collisions with the driver’s structure. It is unknown if Engesa built and offered a 37 mm turret. Both of these proposals were built on CRM hulls.
Bernardini’s Entry
Bernardini would have most likely entered the competition with both the 37 mm turret and the 90 mm turret. The turret which Bernardini offered was the production turret of the X1, which was designated BT-90A1. The Brazilian Army had previously bought 53 HS-90 turrets and D-921 90 mm guns. The issue was that the turret armor of the HS-90 was insufficient for the requirements of the Centro de Pesquisa e Desenvolvimento de Blindados (CPDB) (English: Center for the Research and Development of Tanks). As a result, Bernardini and the Brazilian Army started developing a local turret which was armored with 25 mm thick plates to protect the X1 from .50 cal machine gun fire. The design of the BT-90A1 turret was heavily inspired from the HS-90 turret, with the first prototype of the turret (BT-90) even using some components of the HS-90 turret. The main differences between the HS-90 and the BT-90A1 were the addition of a gun shield on the BT-90A1, improved armor, and the BT-90A1 overall being more bulky than the HS-90. The main difference between the 37 mm and the 90 mm turrets from Bernardini was that the 37 mm turret received a new gun shield and was altered for the 37 mm armament.
Engesa’s design was almost a copy of the turret from the X1 prototype, also known as a BT-90 turret. The turrets differed in a very minor way. The rear sides of the Engesa turret, on which the most rearward smoke launcher was installed, went inwards instead of being a flat plate. It is unknown if this turret used bimetal armor or not. The vehicle was armed with a 90 mm gun and a coaxial 7.62 mm machine gun. In addition to its armament, the turret also mounted 2 pairs of 3 smoke grenade launchers on both sides of the rear turret.
It is unclear which company won this specific bid, as both the Engesa turret and the Bernardini turrets were never mass-produced. What most likely happened, was the switch from the D-921 gun to the license produced EC-90 gun, which was based on the Cockerill 90 mm Mark 3 gun. In 1975, Engesa got a license deal with Cockerill for their 90 mm gun. This turret design bid was most likely initiated in between 1973 and 1975 and probably ended when Engesa got the license deal in order. It is unclear if a new bid for an ET-90 armed turret was opened, but what is known is that Engesa would design the ET-90 turret which would be used on the Cascavels from that point on.
The First Customers for the EE-9 M2 with 90 mm gun
It might be that the Portugal trials are not only responsible for the 90 mm gun on the Cascavel, but also for the hull redesign of the EE-9 production versions to enable them to mount low-profile 90 mm turrets. If this is the case, then it is very likely that the EE-9 M2 trialed in Portugal is in fact an EE-9 M2 hull as we know it today and is potentially even the first prototype of the production hull for both the EE-9 M2 with 37 mm gun and with 90 mm gun.
In any case, the EE-9 M2 became a success with 200 vehicles being ordered by Libya in 1974. Chile also bought 60 EE-9 M2s in the same year. Bolivia followed suit not too long after with 24 EE-9 M2s, but at what exact date the order was made remains unclear. The exact delivery dates also remain somewhat uncertain, but based on a document from Engesa, Libya was the first country to receive its EE-9s. Sourcing is a bit unclear here as the Engesa document states that the EE-9 M2s were delivered over a 2 year period from 1975 to 1976, in seemingly two batches, while another source seems to suggest that they were delivered in a single lot. In general, the wording of Brazilian sourcing seems to be open to interpretation as it usually states when the vehicles were bought and less when they were exactly delivered. As such, all delivery dates will be based on Engesa documents.
EE-9 M3 Cascavel meant for Libya at Santos in São Paulo state.
Source: Engesa EE-9 Cascavel 40 anos de combates 1977-2017
The sale of the EE-9 to Libya also meant that Engesa could take a big step. The order was paid upfront and Engesa used the money to build a large factory in São José dos Campos in São Paulo state to be able to serialy produce the armored vehicles, which was in operation by September 1974. By 1975, Engesa had built its 100th EE-9 and a total of 125 was said to have been delivered to Libya that year. The shipping route from the factory to Libya was quite interesting as well. Considering the EE-9 M2s still used the French HS-90’s, Engesa built the hulls, then shipped the hulls to Toulouse in France where they would mount the turrets. After the EE-9s received the turrets, the vehicles were shipped to Libya.
The Cockerill Gun
Bolivia and Chile received their first EE-9 M2s with the HS-90 turret in 1976 and the orders were completed a year later, in 1977. After the export of the 60 EE-9 M2s with HS-90 turrets to Chile was finalized in 1977, it seems that Chile ordered another batch of 23 EE-9 M2s mounting the new ET-90 I turret with the EC-90 gun. These 23 vehicles were, again, seemingly delivered over a two year period.
In 1975, the first significant design switch was made by Engesa. With 284 EE-9 M2s exported, the French realized that the EE-9 could become a competitor to their own wheeled armored car sales.
Still selling a significant amount of AML-90s at the time and not yet having their own 6 x 6 rendition similar to the Cascavel, the EE-9 could be seen as a better platform than the AML-90. The EE-9 was larger and heavier, but it did offer better mobility through the Boomerang suspension, it offered better armor through bimetal steel plates and it was offered for the same role as the AML-90. In response to the EE-9’s success, the French company SOFMA (which was responsible for the French export sales) recognised that Engesa was dependent on them for building the EE-9s as they had to buy the turrets from SOFMA. It is said that SOFMA started raising its prices to such a degree, that it effectively forced Engesa to look for another option as the HS-90 turret was simply not viable anymore.
Engesa found its solution in Belgium. They acquired the license to produce the low-pressure 90 mm Cockerill 90 Mark 3 gun in 1975 for US$3 million (US$15.5 million in 2021). The gun would be designated EC-90 by Engesa, with the E standing for Engesa, C for Canhão (Cannon), and 90 for the 90 mm gun. This license deal not only made it possible for Engesa to manufacture their own guns, but it also opened the door for them to design their own turrets. In addition, these turrets were also better than the French HS-90 turrets as Engesa incorporated bimetal steel on the turrets as well.
The EC-90 gun schematics.
Source: Manual de Opercão 9110-733-604 – Torre ET-90 II e Armamento
The EE-9 M3 and Recognition
The next step in the Cascavels design was the EE-9 M3. The EE-9 M3 is effectively an EE-9 M2, but with an AT-540 automatic transmission instead of a manual Clark 280V transmission. As such, it is practically impossible to tell an M2 from an M3 from the outside. The only way one could properly distinguish an M2 from an M3 is by going inside the vehicle and looking at an Engesa ID plate to read what kind of gear shift it uses. Considering there seem to be no interior pictures of the supposed EE-9 M3, we have to rely on Brazilian sourcing stating that they were M3s until photographic evidence of those two specific details for what is thought to be an M3.
Using evidence from EE-9s in service with African states, M2 and M3 hulls can be distinguished regardless of the turrets installed. It seems that only the M2 hulls received steel ridges on the front hull to give the crew extra grip, while the M3 hulls received an anti-slip surface instead. Another detail is the rear light configuration. The M2 uses two lights which are next to each other horizontally, while the M3 uses two lights installed vertically. Sadly, the steel ridge detail does not completely hold up for any later modifications to the vehicle as some modified M3 Cascavels appear to have received them on pictures during the Libyan Civil War. In any case, the rear light and anti-slip recognition methods seem to be the most reliable to distinguish M2 and M3 hulls in Africa, regardless of the HS-90 or ET-90 I mounted turrets.
The M3 was the first Cascavel to have an automatic transmission, it was the first to be armed with the 90 mm Cockerill gun in the newly designed ET-90 I turret from Engesa, and it seems to have been the first EE-9 to have received a laser rangefinder. The E of the ET-90 I stood for Engesa, T for Torre (turret), 90 for the armament, and I was added later as Engesa redesigned the first ET-90 turret which would be known as the ET-90 II. It is important to note that the turrets of the Cascavel do not necessarily indicate the model of the EE-9, as the EE-9 M2 has mounted two of the three 90 mm turrets (all but the ET-90 II).
That being said, the EE-9 M2 and M3 do have an exception to this rule. The EE-9 M2 is the only Cascavel hull to have officially mounted the French HS-90 turret and the EE-9 M3 has only officially mounted the ET-90 I turret. A reason for the EE-9 M3 to have only officially used the ET-90 I turret, is because the M3 was only sold to Libya. However, there is proof that Libya and potentially other countries operating the M2 and M3 vehicles have switched around the turrets at some point on a number of EE-9s. The next customer after Bolivia, Chile, and Libya was Iraq in 1979. At this point, the EE-9 hull had received significant redesigns by Engesa and was known as the EE-9 M4.
Iraqi EE-9 M4s, note the integrated hull lights.
Source: Rodolfo Alberto Riascos Rodriguez
The Cascavels’ Finest “Hour’’?
In 1977, the Cascavel supposedly proved itself in combat between the Egyptians and Libyans. From July 21st to 24th Egypt and Libya were engaged in a four day border war, later known as the Egyptian-Libyan War or the Four Day War. Preluding the war, clashes between the two sides intensified on July 12th, 16th, and 19th. Supposedly, during one of these clashes or raids, the Cascavels reached the front much quicker than the other vehicles of the Libyan Army and managed to take out an Egyptian T-55.
It is quite likely that this supposed success happened either at the start of the war or before it, as the Libyan Army was, for all intents and purposes, outclassed and outnumbered by the Egyptian Army. The war ended with a truce although hostilities remained. The success of the Cascavel is thus likely to have been before the war began where its reputation would be less spoiled by the subsequent failure of the Libyan Army.
It is somewhat complicated to properly verify if this statement of the EE-9’s performance in Libya is true, as international press was barred from the conflict zone, leaving reliable information and pictures of the conflict to be desired. If Brazilian sourcing is to be believed, the Cascavel’s remarkable performance caused more countries to take note of the armored car and would end up in more sales for Engesa. How far this is actually the case can be somewhat questioned, as the first order for the EE-9 made after the war was done by Iraq in 1979, and all other orders came after 1980.
Libyan EE-9 M2s.
Source: Engesa EE-9 Cascavel 40 anos de combates 1977-2017
Brazil Gets the EE-9 M2 with 90 mm gun
When Brazil started operating the EE-9 M2 with a 90 mm gun remains a mystery. According to Paulo Bastos, writer for Tecno Defesa and one of the leading experts on Brazilian vehicles, Engesa did deliver a significant number of turretless Cascavels to the Brazilian Army during the 1970s. Refraining from unnecessarily mounting outdated turrets would save the Army a significant amount of money later down the road when they did make a decision. This would not be strange as the Brazilian Army seems to have still discussed the armament for the Cascavel until at least June 1977, considering a 90 mm or an autocannon ranging from 20 to 40 mm.
It might even be after 1978, as a picture shows that at least 9 37 mm armed EE-9s participated during the September 7th parade of 1978, suggesting that the Cascavels were not yet rearmed. In addition, a single EE-9 M2 armed with a 90 mm also appeared during that parade, but it mounted the French HS-90 turret and not the ET-90 with the Cockerill gun.
An EE-9 M2 with the HS-90 turret and Brazilian Cruzeiro do Sul markings at the 7th September 1976 Independence Day parade.
Source: https://youtu.be/Ii6yUDB8xxI
A Deputy Chief of the Brazilian Army suggested the production of the X1A2 light tank in July 1978, which would be armed with the EC-90 to better standardize ammunition with the EE-9s. It is thus a distinct possibility that the eventual choice to arm the Brazilian Cascavels with the EC-90 gun was made sometime between June 1977 to July 1978.
This might be further supported as the first batch of 148 EE-9 M2s delivered until 1978, all used the same parts catalog, while an additional 9 EE-9 M2s delivered in 1980 fell under a new catalog. This time gap might suggest that in between 1978 and 1980, the Brazilian Army made its choice and initiated the arming and rearming of the EE-9s with the ET-90 I turrets.
This theory is also further corroborated by a maintenance manual for an M2 Cascavel from the Brazilian Army with the designation MM 022 06 79. This manual shows a Cascavel M2 with a HS-90 turret, but with the D-921 gun having a “photoshopped’’ EC-90 muzzle brake instead. The appearance of a manual for a 90 mm armed EE-9 Cascavel seems to suggest an official incorporation of the vehicle within the Brazilian Army.
The writer thinks that the MM 022 06 79 designation means Manual de Manutencão of the date 22-06-79 or June 22nd 1979. This thought seems to be further supported with a Colombian operational manual for the EE-9 with the designation 09682, of which 1982 would be the year when Colombia received their Cascavels. Another Brazilian manual with the designation of 12782 for the M6 Cascavel also points toward 1982, which is the year the Brazilian Army received a number of M6 Cascavels.
The EE-9 M2 with the altered muzzle brake.
Source: Engesa Manual MM 02 06 79
The website Armas Nacionais does claim to have a more specific date on when the Brazilian Army received their first 90 mm EE-9s and on how many. According to Armas Nacionais, the Brazilian government signed a contract with the Army after the delivery of the initial 102 EE-9 M2s for the rebuilding of 60 EE-9 M2s in 1976. This does line up with the order/delivery dates of these 102 EE-9s. The first batch of EE-9s with 90 mm guns arrived in 1977 and another batch of 46 EE-9 M2s was ordered in the same year. In 1980, the Brazilian Army ordered another 9 EE-9 M2 Cascavels, making the total number of 90 mm armed EE-9 M2s operated by Brazil at 115.
The dates and numbers mentioned do line up with when the Cascavels were ordered and delivered by other sourcing, but these sources do not specifically mention when these conversions were carried out, nor when Brazili received their first batch. In addition, the writer has been unable to confirm the story from Armas Nacionais with the sourcing used in their article.
All in all, the Armas Nacionais explanation is not a bad explanation with the numbers and dates lining up. Sadly, no other source so far confirms this. Another strange detail is that this would mean that a total of 42 EE-9s would remain unconverted unless these were converted at a later date. Regardless, it is clear that the Brazilian Army lists a total of 157 EE-9 M2s of various series in their service and that the arming of them with the 90 mm seems to have begun somewhere in between 1976 to 1979.
The 90 mm armed EE-9 M2 of Brazil.
Source: Private collection
The EE-9 M2 and M3 in Detail
The EE-9 M2 with 90 mm gun weighed 10 tonnes empty and 11 tonnes combat-loaded (11 and 12.1 US tons respectively). It was 6.22 m (20.4 feet) long including the gun and 5.19 m (17 feet) without the gun. It was 2.59 m (8.5 feet) wide and about 2.3 m (7.55 feet) tall with the HS-90 turret. The EE-9 had a crew of three, consisting of the commander/loader (turret left), gunner (turret right), and the driver in the middle front hull.
An EE-9 M2 or M3 during testing, most likely at the Marambaia testing grounds.
Source: Engesa Brochure
Hull
The hull of the EE-9 M2 was manufactured from welded bimetal steel plates. The upper front plate was well angled at 60º from vertical. The hull also featured two covers which were mounted on the hull at the positions above the Boomerang suspension, effectively functioning as mudguards and very minor spaced armor.
The front upper hull plate presented 16 mm (0.63 inch) of bimetal armor at an angle of 60º. The sides and rear were 8.5 mm (0.33 inch) thick at varying angles, and the top and bottom hull were 6.5 mm (0.26 inch) thick. The front of the EE-9 was meant to protect from .50 machine gun fire at an unknown range, while the entire vehicle was protected from 7.62 mm AP rounds at 100 m (109 yards), and standard 7.62 mm rounds at 50 m (54 yards).
The EE-9 had two headlights externally mounted on top of both sides of the upper front hull plate. A rearview mirror could be mounted on both headlight guards. A black-out light was installed on the right side of the left headlight. Below the driver’s hatch was a foldable windshield, which the driver could use when driving with an open hatch. The driver’s hatch was a two-piece hatch, with the front part being part of the upper front plate, while the back part was part of the top hull plate. The front hatch had three periscopes for the driver for 180º of vision. Interestingly, the Libyan EE-9’s only had 1 periscope. These periscopes and other periscopes or sights would not have been active or passive night vision equipment unless the Cascavel was ordered with these devices. The standard periscopes were manufactured by D.F. Vasconcellos.
A frontal view of the EE-9 showing the headlights, the windscreen, and the 3 periscopes.
Source: Engesa Brochure
It is interesting to note however, that all the Libyan EE-9s (M2s and M3s) use a single driver’s periscope. It is unknown why this was done, as the three sight EE-9’s were already around at the time. It might have been to save money or the Libyans might simply not have seen the use of the extra periscopes providing a larger view arc.
A ventilation inlet was installed on both upper hull side plates, these ventilation inlets are recognizable by their frustum shape. A siren was installed behind the ventilation inlet on the right side of the vehicle. The fuel tank cap of the Cascavel was located on the left side, in the middle of the upper side hull plate, with the fuel tank installed on the hull floor. The EE-9 had a large ventilation grille on the rear of the vehicle, reminiscent of the M8, and had a rear light on both sides of the ventilation grill. The engine could be accessed through two large hatches on the hull top rear.
Interior of the EE-9 M2 at the Saumur Tank Museum, with the operating panels on the two pictures on the left, the steering wheel in the 3rd picture from the left, and the gear shift on the most right.
Source: Saumur Tank Museum
The M2 used an adjustable hydraulic powered steering wheel for steering and had 3 pedals: the clutch for gear shifting on the left side of the steering wheel, the brake on the right side of the steering wheel, and the throttle to the right of the brake. The gear shift stick was located to the right of the driver. A control panel was located on the front left of the driver for, among other things, the headlights, siren, windshield, and interior lighting. The dashboard was located to the right which included a speedometer, ignition switch, fuel meter, and temperature meter among other things.
What the driver’s station on the M3 looks like is unknown, but it is thought to be fairly similar to the stations of later Cascavels which use automatic transmissions. This would mean that the gear shift stick was replaced with a gear selector stick and the clutch pedal was removed. In essence, both the M2 and M3 are essentially driven like cars.
Mobility
The EE-9 M2 used the OM352 and the OM352A engines, while the M3 only used the OM352A engine. These are both 6-cylinder inline diesel engines of which the OM352A is turbocharged. The OM352 produces 125 hp at 2,600 rpm and 353 Nm at 1,600 rpm, while the OM352A produces 172 hp at 2,800 rpm (DIN standard) and 431 Nm at 1,800 rpm. The Brazilian Army seems to have only used the OM352A engine, although it is unknown if early Brazilian Cascavels might have received the standard OM352 engine to be rebuilt or replaced later on. Libya is the only country to have operated the OM352 with certainty in their first 200 EE-9 M2 Cascavels, the other operators only used the OM352A.
An OM352A in a Brazilian EE-9 M2 on the right and the oil tank on the front left.
Source: Adriano Santiago Garcia
The M2 Cascavel had a top speed of 95-100 km/h (59 mph) and an operational range of 750 km (466 miles). It had a turning radius of 7.7 m (8.1 yards) and it could ford a depth of 1 m (3.3 feet). The Cascavel could climb a 35º slope, could climb a vertical obstacle of 0.65 m (2.1 feet), cross a 1.65 m (5.4 feet) trench, and had a ground clearance of about 0.5 m (1.6 feet). The front-wheel could travel for 0.2 m (0.66 feet), while the rear wheels could travel for 0.9 m (3 feet). It used 12 X 20 run-flat tires with a diameter of 0.5 m (1.6 feet). The EE-9 M2 had a distance between the front axle and rear axle of 2.8 m, and a distance of 1.4 m (4.6 feet) between the two rear wheels.
The EE-9 M2 used a manual Clark 280V transmission with 5 forward and one reverse gears. The EE-9 M3 used an AT-540 automatic transmission instead, with 4 forward and one reverse gears. The automatic transmission would make the vehicle much easier to drive and significantly reduced the chance of misshifts in stress situations.
The plate on the Clark transmission of the EE-9 M2 in Brazil.
Source: Adriano Santiago Garcia
In addition, the Cascavel used an Engesa 2 speed transfer case, which allowed the Cascavel to be used in reduced and high gear. By putting the Cascavel in reduced gear, horsepower was sacrificed for an increased torque, making it more effective in climbing slopes. The vehicle was 6 x 6 driven, of which the rear 4 wheels were part of the Boomerang suspension. The Boomerang suspension, in combination with the Engesa 2 speed transfer case, enabled the Cascavel to cross challenging terrain and provide maximum traction in most situations.
The drivetrain of an EE-9.
Source: Engesa Manual
The power of the engine was distributed to a differential on the front side of the vehicle, and a differential in the rear. The rear differential drove the Boomerang suspension with a single axle, which made the Boomerang suspension such an ingenious design.
In 1969, this suspension was invented by Engesa to enable trucks to transport oil to the refineries through rough terrain with bad infrastructure. With this suspension, the trucks could traverse otherwise untraversable hills for conventional suspension systems, as the wheels would always stay in contact with the ground to provide maximum traction.
The suspension system was a two wheeled-single axle driven suspension. The advantage of the Boomerang suspension was that it could be fitted on existing differentials with a single axle. Normally, this meant that the single axle, designed for the torsion forces of a single wheel, was subjected to the torsion forces of two wheels. Through excellent engineering, half of the torsion forces of the two wheels were mitigated by the suspension system built around the original axle. This design not only enabled the drive of two wheels by a single axle but with clever usage of gears and bearings on both the axle and tube around the axle, the suspension system can rotate around its axle for 360º. This ability to rotate in extreme angles would enable the vehicles to traverse very difficult terrains and still provide maximum traction, as the suspension system curved with the terrain so that all the wheels were always in contact with the ground.
Exploded view of a Boomerang suspension.
Source: Engesa Manual
The Boomerang suspension used leaf springs for dampening. The two front wheels were used for steering. The wheels on the Boomerang suspension all rotated at the same speed. The front wheels were dampened by large coil springs. The vehicle used hydro-pneumatic drum brakes, and was steered with hydraulics as well.
A Central tyre Inflation System (CTIS) was also offered by Engesa for the EE-9 M2 and M3, but it is unknown if any if the M2s or M3s were sold with this system. The Brazilian Army does not seem to have the CTIS on the M2 or many of their other EE-9s either.
Turret
The EE-9 M2 used both the HS-90 and the ET-90 I turret, while the M3 officially only mounted the ET-90 I turret, although turrets seem to have been switched around on a number of different vehicles in Libya. The HS-90 was the imported turret and the ET-90 I was the locally produced turret and essentially a redesigned HS-90 turret. It shared many concepts and had a fairly similar design. The main difference between the two were armament and materials, as the ET-90 I used both a Cockerill gun and bimetal armor, making it the superior turret.
The Brazilian Army only officially operated the ET-90 I turret on the EE-9 M2s, although a single vehicle in Brazilian markings with the HS-90 turret was shown on the September parade of 1978.
HS-90
The HS-90 turret was manufactured from steel plates welded together. The turret’s armor ranged from 14-15 mm frontally to 7-8 mm in the rear. It was manned by a two-man crew, with the commander/loader on the left and the gunner on the right. The commander’s position can be easily recognized by the dome-shaped cupola. Both crew members had their own hatch, which opened to the rear.
The cannon was aimed with a direct sight telescope coaxial to the gun with 6x magnification. The commander and gunner each had access to 4 sights, all with 1x magnification. A laser rangefinder could be installed on top of the gun shield if requested, although this never seems to have been done on the HS-90 turrets for the EE-9. The turret also had a spotlight on the left front side of the commander’s hatch. A ventilation inlet was located on the top of the turret on the rear.
The turret stored 24 rounds of 90 mm ammunition, of which 12 rounds on the left side of the turret bustle and another 12 rounds in two 6 round-revolver style magazines behind the gunner and the commander. The turrets stored 2,000 rounds (10 boxes) for the 7.62 mm coaxial machine gun, of which at least 6 were stored in a magazine in the frontal part of the turret basket floor.
The turret had a gun depression of -8° and an elevation of +15°, a mechanical drive system and an electrical system functioning on 24 V. It also had 6 76 mm smoke launchers, of which 3 on each rear side of the turret. A roof-mounted 7.62 mm anti-aircraft machine gun, active or passive night vision sights, and laser rangefinder were offered as optional equipment for the turret by Engesa.
A schematic interior view of the HS-90 turret.
Source: Panhard Armored Car Enthusiasts’ manual
ET-90 I
The ET-90 I turret was manufactured by Engesa from a welded bimetal steel plate structure. The turret was armored with 16 mm thick plate allround except for a 8 mm thick plate on the top. It was manned by a two-man crew, with the commander/loader on the left and the gunner on the right. The commander’s position can be easily recognized by the dome-shaped cupola. Both crew members had their own hatch, which opened to the rear.
The ET-90 I turret.
Source: Engesa manual
The ET-90 I turret is, for all intents and purposes, a simplified copy of the HS-90 turret, but superior. It is very likely that you could put the crew from an AML-90 into an ET-90 I turret, and they would be able to operate the turret with the same efficiency from the start, except for having to adjust for the increased muzzle velocities of the EC-90 (license produced Cockerill Mk.3) main gun. This decision not only made it easier for Engesa to produce the turrets and save in development time, it also made it easier to market to countries already operating HS-90 turreted vehicles looking for a replacement. This makes sense considering the HS-90 turret is one of the most widely used turrets on armored cars in the world.
Ammunition stowage of the ET-90 I in the turret bustle.
Source: Engesa Manual
The ET-90 I is a wider turret than the HS-90 in order to simplify its design, sacrificing turret profile for simplicity. At the same time, it could be argued that the larger profile might offer more effective turret ergonomics for the crew and that the usage of bimetal steel compensates for the larger turret profile as well, as it is more effective than monosteel. A clear example of the simplified construction are the commander and gunner hatches. Where the HS-90 had a structure welded to the turret sides with sights integrated in them, Engesa simply widened the turret so they could use a single plate and would not have to make use of such a structure.
The cannon was aimed with a direct line-of-sight telescope from D.F. Vasconcellos coaxial to the gun with 6x magnification. The commander and gunner had access to 4 sights manufactured by D.F. Vasconcellos, all with 1x magnification. These periscopes gave an instantaneous 46° horizontal and 9° vertical field of view, and a total 55° horizontal and 18° vertical field of view. The turret also used a spotlight on the left front side of the commander’s hatch, although this did not seem to be common practice. A ventilation inlet was located on the top of the turret on the rear.
A sketch showing all the vision devices of the ET-90 I turret.
Source: Engesa Manual
The turret stored 24 rounds of 90 mm ammunition, of which 12 rounds on the left side of the turret bustle and another 12 rounds in two 6 round-revolver style magazines behind the gunner and the commander. The turrets stored 2,000 rounds (10 boxes) for the 7.62 mm coaxial machine gun, of which at least 7 were stored in a magazine in the frontal part of the turret basket floor and 1 next to the gunner.
Turret basket of the ET-90 I
Source: Engesa Manual
The turret had a gun depression of -8° and an elevation of +15°, a mechanical drive system and an electrical system functioning on 24 V. It also had 6 smoke launchers, of which 3 on each rear side of the turret. A turret top mounted 7.62 mm anti-aircraft machine gun, active or passive night vision sights and laser rangefinder were offered as optional equipment for the turret by Engesa.
Armament
The EE-9 M2 used both the French DEFA D-921 90 mm low pressure gun and the license produced EC-90 gun, while the EE-9 M3 only officially used the EC-90. The EC-90 had a number of advantages over the D-921 gun. The first was increased muzzle velocity from 750 m/s to 890 m/s for the HEAT (High Explosive Anti-Tank) round. This meant that the projectile had a flatter trajectory making it more accurate and it allowed the Cockerill gun to engage targets at longer ranges.
The other slight advantage was ammunition variety. The EC-90 had access to HESH (High Explosive Squash Head) rounds and Engesa attempted to develop an APFSDS (Armor Piercing Fin Stabilized Discarding Sabot) round in the mid-1980s. The latter round was never finalized however and remained a prototype batch.
The APFSDS performance was more or less on par with that of the HEAT round. It would have provided a muzzle velocity of 1,176 m/s if Engesa had finished its development. Engesa had also started development of a canister round which was never finalized either. In any case, the development of the APFSDS and canister rounds were only initiated around the mid-1980s, when the M2 and M3 Cascavels were no longer in production anymore. The final advantage of the EC-90 over the D-921 is that Engesa could license produce it instead of having to buy both the gun and turret.
An Engesa employee with an APFSDS round of the EC-90 at Engesa’s test range.
Source: Private collection
The main advantage the D-921 gun had over the EC-90 is that the D-921 was sold with the OCC 90-62 HEAT round. The OCC round had a penetration of 320 mm against the 250-260 mm of the NR478 of Engesa. The exact reason for this rather large disparate performance is somewhat unclear. Considering France had significant experience with HEAT ammunition, such as Obus G technology, some of these developments might have carried over to the OCC 90-62 HEAT round. The OCC 90-62 is not an Obus G round however. A difference in spin rate and explosive filler type might also have contributed to this disparity or the overall interior design.
Another detail that could be taken into account is the manner of testing. The NR478 is rated at 300 mm when it is tested as a static round (not fired from a gun but discharged point blank at a fixed position). The number of the OCC 90-62 might have come from static testing as well, which would mean that the actual performance might be a bit less. In Jane’s Armour and Artillery 1985-1986, the NR478 is rated as 300 mm at 1,000 meters, while in Engesa’s marketing material and in some table for the Cockerill rounds it is listed as 250 mm. What the correct penetration is, will likely remain a mystery until someone manages to find test reports on both rounds to see where these numbers exactly come from.
90 mm D921
Round
Capability
Effective range
Velocity
HEAT (High Explosive Anti-Tank)
320 mm (12.6 inch) flat at any range.
1,500 meters (1,640 yards)
750 m/s
HE (High Explosive)
Lethal radius of 15 meters (16 yards)
1,500 meters (1,640 yards)
650 m/s
White Phosphorus – Smoke
50 meter wide smoke screen for 20 to 30 seconds
1,500 meters (1,640 yards)
750 m/s
HEAT-TP (High Explosive Anti-Tank – Training Projectile)
Inert (no explosive filling)
1,500 meters (1,640 yards)
750 m/s
The firing table and the ‘’crosshair’’ of the direct-fire telescope for the EC-90 gun went up to 3,000 m for the HEAT round, 2,380 m for the HE and smoke round, and 1,020 m for the coaxial machine gun. The main armament was fired with a pedal on the turret basket floor and could be cut off through the main electrical system box. This box controlled things such as the ability to fire the main and coaxial armament, configure the ventilation system, and internal lights. In some EE-9s, the firing table was added as a plate on the electrical system box as well. The electrical system box was mounted to the right of the gunner. Additional control boxes would be added for equipment such as laser rangefinders and day/night sights if needed.
The ammunition for the EC-90 gun lined up from left to right: High Explosive, HEAT Training Projectile, High Explosive Squash Head, High Explosive Anti-Tank, Smoke.
Source: Jane’s Armour and Artillery 1985-1986
Although the EC-90 is able to fire a wide variety of ammunition, according to inside sources, the Brazilian Army only uses HEAT, HEAT training projectiles, and HE rounds for the Cascavels. This might change during wartime however. Imbel is responsible for the manufacture of these rounds in Brazil after Engesa’s ammunition manufacturing subsidiary Engequímica went bankrupt along with Engesa in 1993.
90 mm EC-90
Round
Capability
Effective range
Velocity
HEAT – NR 478A1 (High Explosive Anti-Tank)
250 mm-300 mm (9.8-11.8 inch) flat at any range.
2,000 meters (2,185 yards)
890m/s
HESH – NR 503A2 (High Explosive Squash Head)
Meant for bunkers, walls and light vehicles.
2,000 meters (2,185 yards)
800 m/s
HE – NR 501A1 (High Explosive)
Lethal radius of 15 meters (16 yards)
1,600 meters (1,750 yards)
700 m/s
White Phosphorus – Smoke – NR 502A2
50 meter wide smoke screen for 20 to 30 seconds
1,600 meters (1,750 yards)
695 m/s
HEAT-TP – NR 479A2 (High Explosive Anti-Tank – Training Projectile)
Inert (no explosive filling)
2,000 meters (2,185 yards)
750 m/s
The ET-90 I turret used a 7.62 mm N model F-1 machine gun as its coaxial armament. In theory, it could fire 700 rounds per minute, while the practical rate of fire was about 250 to 300 rounds per minute. Its maximum range was 1,200 m and it weighed 10.5 kg. The coaxial machine gun was installed on the commander’s side as the commander acted as the loader, but was fired by the gunner through a button on the main gun’s elevation handle. It could be manually fired by the commander if needed.
Sketch of the F-1 machine gun.
Source: Engesa manual
The EE-9 carried 2,000 rounds of 7.62 ammunition, divided between 10 cases, and a total of 44 rounds for the main gun, of which 20 were stored in the hull and 24 in the turret. The hull ammunition storage was offered as an optional feature and consisted of boxes installed between the front wheel and the turret ring on both sides. The Brazilian EE-9s seem to operate with the hull stowage racks.
The Brazilian EE-9s are said to operate with night sights in the manuals, but inside sources dispute this claim and state that the EE-9 only uses day sights. How far this is true remains to be seen and it might only be valid during peacetime operations, although the vehicles do not use the SS-122 day/night sights which were sold by Engesa. What is true, is that almost none of the Brazilian EE-9s operate with a laser rangefinder, with only one or two vehicles mounting it, which are either EE-9 M6s or M7s. In addition, the traverse and elevation systems of the Brazilian EE-9s are all manual and not electric, even though electric drives were optional choices. All in all, the Brazilian EE-9s are quite barebones when it comes to fire control systems.
Other Systems
The power of the EE-9 was divided in a 12 V and a 24 V circuit, of which the 24 V circuit was mainly meant for the turret and the 12 V circuit for the general operation of the hull. It used 4 batteries of 12 V and 95 Ah, which were located in the engine bay. In addition, it used a K1 Alternator of 12/14 V and 55 A and a 12V 4 hp starting engine.
The exact radios used in the EE-9s are unknown. The VHF/FM and/or HF/SSB and intercom systems were offered as optional equipment by Engesa. The Brazilian Army used equipment which received their EB11 radio systems, which were widely used in the Brazilian Army. Among potential installations were the EB11 ERC-201 according to a contact in the Brazilian military, or the EB11 ERC-204 which was mounted in an Urutu. A Brazilian Army contact claims that the current Brazilian Cascavels do not use radio equipment or intercoms as the old EB11 radios have been phased out but not replaced by the Brazilian Army. To what extent this is true is unverified, but various videos showing the interior of the EE-9 do not show radios or the usage of intercom equipment.
Supposedly, the lack of radios and intercoms were a result of the EE-9 programs being in limbo. It was uncertain if they were going to be modernized and it was unclear how quickly they were going to be replaced. The lack of a radio has been somewhat solved by using Falcon walkie-talkies with a range of about 10 km, and it should be completely resolved with the modernization program.
Additional features such as a heater and air conditioning system were offered for the EE-9 as well. Interestingly, these two options seem to have been dropped in later variants or at least no longer mentioned in brochures. It might be that there was simply no demand for the systems or it might have had some practical issues. In any case, it is unknown if any Cascavel was equipped with either a heater or air conditioner by Engesa.
The EE-9 did have a ventilation system in the turret and hull to ventilate the fumes from firing the main cannon. Air was sucked from the air intake on the rear turret top and blown out in front of both the commander and gunner on the turret top. The toxic fumes were sucked in through a duct on the rear side of the turret, with an exhaust mounted in the middle of the turret bustle. The hull had two exhaust fans located at the frustums on both hull sides. It is possible that this was the air conditioning system and that it was nothing more than a basic ventilation system.
A sketch of the ventilation system of the ET-90 I.
Source: Engesa manual
Organization
Cascavels can be found in a number of brigades (army > division > brigade > regiment > squadron > platoon) within the Brazilian Army, which are in turn subdivided into either regiments or squadrons depending on the type of brigade. The vehicles are used in 7 different types of brigades and 15 brigades in total. The EE-9s are operated in Mechanized Cavalry Squadrons and Mechanized Cavalry Regiments (Esquadrão de Cavalaria Mecanizado and Regimento de Cavalaria Mecanizado respectively) within these brigades. There is one exception, as the 14th Mechanized Cavalry regiment is bound under a division, not a brigade.
List of Brigades, Regiments and Squadrons using the EE-9 in the Brazilian Army (2020)
Division/Brigade type
Division/Brigade
Regiments or Squadrons
Army division
5a Divisão de Exército
14° Regimento de Cavalaria Mecanizado
Jungle infantry brigade
1a Brigada Infantaria de Selva
12° Esquadrão de Cavalaria Mecanizado
Mechanized infantry brigade
15a Brigada Infantaria Mecanizada
16° Esquadrão de Cavalaria Mecanizado
Light infantry brigade
4a Brigada Infantaria Leve (Montanha, Mountaineers)
4° Esquadrão de Cavalaria Mecanizado
11a Brigada Infantaria Leve
13° Regimento de Cavalaria Mecanizado
Motorized infantry brigade
3a Brigada Infantaria Motorizada
3° Esquadrão de Cavalaria Mecanizado
7a Brigada Infantaria Motorizada
16° Regimento de Cavalaria Mecanizado
8a Brigada Infantaria Motorizada
8° Esquadrão de Cavalaria Mecanizado
9a Brigada Infantaria Motorizada
15° Regimento de Cavalaria Mecanizado
10a Brigada Infantaria Motorizada
10° Esquadrão de Cavalaria Mecanizado
Armored infantry brigade
6a Brigada Infantaria Blindada
6° Esquadrão de Cavalaria Mecanizado
Armored cavalry brigade
5a Brigada Cavalaria Blindada
5° Esquadrão de Cavalaria Mecanizado
Mechanized cavalry brigade
1a Brigada Cavalaria Mecanizada
1° Regimento de Cavalaria Mecanizado
2° Regimento de Cavalaria Mecanizado
19° Regimento de Cavalaria Mecanizado
2a Brigada Cavalaria Mecanizada
5° Regimento de Cavalaria Mecanizado
8° Regimento de Cavalaria Mecanizado
3a Brigada Cavalaria Mecanizada
3° Regimento de Cavalaria Mecanizado
7° Regimento de Cavalaria Mecanizado
12° Regimento de Cavalaria Mecanizado
4a Brigada Cavalaria Mecanizada
10° Regimento de Cavalaria Mecanizado
11° Regimento de Cavalaria Mecanizado
17° Regimento de Cavalaria Mecanizado
The structure of the squadrons and regiments is a little different, with the regiments operating a command and support squadron alongside three mechanized platoons in which the Cascavels are operated. The squadrons very roughly forgo the command and support squadron and only use the command and subcommand group and a mortar platoon alongside the three mechanized platoons.
Each mechanized platoon operates a command group, 2 exploration/pathfinder groups, a wheeled armored reconnaissance vehicle section, a combat group, and a support part. The wheeled armored reconnaissance vehicle section operates 2 EE-9 Cascavels. This means that every cavalry regiment and squadron of the Brazilian Army actively operates 6 EE-9s in total.
The Brazilian Army has 23 cavalry regiments and squadrons, which means that Brazil theoretically operates 138 EE-9s. One of the regiments owns 19 Cascavels, which is a little over three times the number they actually operate. If this is taken as a rule of thumb, it would mean that Brazil needs about 414 EE-9s of which a third are in active service and two thirds are in reserve/stocks. This number is reasonable considering the Brazilian Army bought 409 EE-9s of all types from Engesa.
Brazilian Service
Despite operating a total of 157 EE-9 M2s and a total of 409 EE-9s (excluding 6 EE-9 M4s from the Corpo de Fuzileiros Navais; the Brazilian Marine Corps), Brazil never really did anything with the vehicles, while the more modern M7s would be used in the 1996 UN peacekeeping mission in Angola and to suppress the strike at the CSN steel factory in 1988 as passive onlookers.
The actual service number of EE-9s is somewhat in question as well. The current numbers are based on the initial delivery figures by Engesa and do not include any written off vehicles over the years. Some vehicles have been used as part donors and some might simply not be in operation anymore due to old age and bad maintenance. Although the number of actual usable Cascavels is unknown, it is almost certainly less than 409 which has been the active service number since 1988, with the first EE-9s entering service in 1975.
Modernization and Replacement
The first modernization program was proposed to the Brazilian Army by QT Engenharia e Equipamentos Ltda in 1995, 2 years after Engesa’s Bankruptcy. An EE-9 M2 and an EE-11 M2 were modernized by the company with the goal of modernizing as many vehicles in Brazil’s fleet as possible. QT Engenharia won the bid to modernize the two previously mentioned vehicles which were remnants from Engesa’s old stocks when they went bankrupt. The Cascavel received a new fire control system which used night vision and a laser rangefinder, with night vision blocks for the commander, driver and gunner. An automatic transmission was installed, considering the EE-9 M2 did not have access to one, and the drum brakes were replaced with disc brakes. A more powerful 280 hp engine was also considered. The project would have converted every Brazilian EE-9 to an improved version of the most advanced EE-9 Engesa offered until its bankruptcy, offering a more powerful engine than any EE-9 had at the time.The project was canceled in the late 1990s due to high costs.
The only available picture of the QT Engenharia upgrade proposals.
Source: Blindados no Brasil
It is important to note that not a single EE-9 in Brazilian service (April 2022, Cascavel modernisation not yet in service) uses any form of night vision equipment. Although night vision periscopes are mentioned in the manuals, official Army documents and inside contacts dispute this claim and specifically state that not a single EE-9 has these periscopes in the Brazilian Army. In addition, only a handful of EE-9s in the Brazilian Army use a laser rangefinder.
In 1997, the AGSP (Arsenal de Guerra de São Paulo, São Paulo War Arsenal) effectively inherited the role of the PqRMM/2, the maintenance park which had created the prototypes of the Cascavels and had paved the way for a national defense industry. The AGSP was tasked with finding ways to extend the service life of the EE-9 and the EE-11 until they would be replaced by the Guarani and an 8×8 Fire Support Vehicle. The AGSP was not only in charge of modernisation, but also became the most important maintenance location for the EE-9 and the EE-11. This was important as Engesa’s collapse meant that maintenance had ground to a halt for Brazil and all Engesa’s customers. The AGSP collected the modernized vehicles by QT Engenharia after the project was canceled, where they supposedly reside to this day. The AGSP also carried out a modernisation project of their own.
In 1998, the AGSP mounted a full-scale mock up of a low altitude air defense system armed with 2 Piranha missiles on both an EE-9 M2 hull and a more modern EE-11 hull. This system was known as Simbada, an acronym for Sistema de Defesa Aérea a Baixa Altura which translates to Low Altitude Air Defense System. The concept was not further developed on either the EE-9 or EE-11.
The EE-9 M2 with the SIMBADA system mounted in place of the turret.
Source: Blindados no Brasil
The AGSP initiated its maintenance line in 2001 and had refurbished and standardized more than 200 EE-9s and EE-11s by 2011. The goal set was to fully refurbish about 500 EE-9s and EE-11s out of the combined total of 639 EE-9s and EE-11s. How many have been refurbished fully is unknown. What is known is that the refurbishment process began with the newest vehicles and would work its way through the older vehicles.
It is however very likely that the EE-9 M2 will be phased out and retired from service in the coming decade. Brazil is planning to replace its Cascavel fleet with a yet unknown (April 2022) 8×8 Fire Support vehicle like the B2 Centauro or the LAV-700. To bridge the transition process from EE-9 to the new FSV vehicles, Brazil has initiated a modernisation program for its Cascavels. The modernized EE-9 will receive a new drive train, new fire control systems, and a command and control computer system among other upgrades.
Scale model of the B2 Centauro with a Brazilian camouflage presented at the Iveco factory when the 500th Guarani was delivered.
Source: Caiafa Master
The prototype of this modernisation was built by Equitron, which designated the vehicle EQ-12. The Army designated the modernized vehicle as EE-9U, and the AGSP as MX-8. An EE-9 M2 was again the test subject for this modernisation program and it was delivered to Equitron in the middle of 2014.
Equitron initiated its modernisation and would also acquire the contract for a further modernisation of the turret, which was to be fully automated (the initial modernisation had not yet proposed extensive turret modernisations). By 2016, the modernized EE-9 M2 was completed and Equitron is currently trying to secure the contract for the modernization of 98 to 201 EE-9s.
These limited numbers could suggest that the EE-9 M2s will be phased out in the coming decade or two as it is the oldest of all the EE-9s in service. It is unlikely that the EE-9 M2 will be modernized due to its age and will either continue operations in its current state until it is replaced by the 8×8 FSV or the vehicles will be put in storage. Regardless, the future of the EE-9 M2 is uncertain.
Another interesting modernisation of the EE-9 appeared in 2019, which was built on the exact same hull as the EE-9U prototype, evidenced by the exact same registration. An EE-9 armed with a TORC-30 turret was presented by ARES Aeroespacial and Equitron at the LAAD Defence and Security exposition. The prototype has not yielded any success so far and the original modernized turret of the EE-9U was again mounted on the hull.
Maintenance
One of the biggest challenges Brazil and many other countries using Engesa vehicles had to face after Engesa’s bankruptcy in 1993, was maintenance. Engesa would have been hired to do extensive maintenance work or refurbishment, but users had to figure out what to do with the vehicles they had. Colombia attempted to copy the EE-11 Urutu by creating the Zipa, but this was unsuccessful. The AGSP took on the role of maintaining the Brazilian fleet in Brazil.
Luckily, a number of companies arose after Engesa’s bankruptcy to keep maintaining the vehicles. Companies such as Universal and Columbus International were founded or started supplying spare parts for Engesa vehicles shortly after Engesa’s bankruptcy. Universal was already around in 1967, providing the Brazilian Army with parts from that point onwards. In 1992, it started supplying components for Engesa vehicles with Engesa’s impending bankruptcy and in between 1996 and 2000 the company managed to buy up a large number of vehicles, machines, equipment, tools, and about 30,000 components from Engesa’s bankruptcy auctions. From this point onwards, Universal would start maintaining vehicles for Brazil and other countries and even sold 8 Urutus to the Brazilian Army.
Logo of Columbus.
Source: Columbus
Columbus was founded in 1993 by ex-Engesa employees with the goal of maintaining, modernizing, and developing new projects for Brazil and the countries that operated Engesa equipment. Columbus would go on to develop the Marruá jeeps of which the designs were sold to Agrale. The Marrua is effectively a redesigned EE-12 jeep and is slowly replacing the Brazilian Army’s old jeeps and has seen export success as well. Columbus and Universal both ensured that the Cascavel and Urutu would still have many service years ahead of them and would support the AGSP in maintaining them.
When an EE-9 or EE-11 arrives at the AGSP for maintenance it is fully disassembled. Each component will then be sent for individual checks and maintenance. The hull will be stripped of paint with a sandblaster and subsequently repainted. The entire vehicle will then be reassembled and tested.
Among specific services are the complete overhaul of engines and replacement of the 50 A alternator with 75 A alternatives as the 50 A is not locally produced anymore. The AGSP also does overhauls for the entire drivetrain with the incorporation of some minor improvements over the original design. The turret and armament will be overhauled as well with a potential replacement for the gun if needed, as there are Cascavels still using the original gun breeches from Engesa.
Tyre Shortage
Brazil suffered a tyre shortage for the EE-9 and EE-11 after Engesa went bankrupt from 1993 until at least 1995. The tyres were not mass-produced by the Brazilian industry as the specific manufacturing process of the run-flat tyres was no longer used. The Brazilian Army opted to import Continental tyres from the Czech Republic but these were rejected during testing. The solution was found in using locally produced truck tyres instead, which the Colombians had been doing for some time.
This shortage lasted until at least 1995 and potentially until 1997 or longer. Fourteen EE-11s and 2 EE-9 M7s were sent to the UNAVEM III (United Nations Angola Verification Mission III) UN peacekeeping mission in Angola in 1995. In order to provide the spare tyres needed, the tyres of a number of EE-9s or EE-11s of the Brazilian Army were cannibalized. This lack in tyres is likely a contributing factor for the Brazilian Army to actively start looking for a solution to the matter, even though this should have been done the moment Engesa went bankrupt.
The 2 EE-9 M7s sent to Angola.
Source: Engesa EE-9 Cascavel 40 anos de combates 1977-2017
The harrowing need of the Brazilian Army having to cannibalize tyres for a 2 year mission with just 16 vehicles is indicative of Brazil’s incapability to fight any sort of war with the 609 EE-9s and EE-11s during this time period as no spare tyres would have been available in the initial stages of a potential war. The lack of initiative from the Brazilian Army to solve the issue quickly might have come from the economic difficulties of Brazil during the 1990s or due to bureaucratic issues.
Foreign service
The foreign service of the EE-9 M2 and M3 will be divided in two sections: first with direct exports to Bolivia, Chile, Libya, and a second with international actors that acquired the EE-9 through exports, donations, and captured equipment. Libya has, for example, donated or lost a significant number of the 400 EE-9s they bought from Engesa.
Direct Exports:
Bolivia
Bolivia received 24 EE-9 M2s with the HS-90 turret from Engesa around 1976-1977. They were painted in a yellow and brown camouflage scheme, although the Bolivian EE-9s have been repainted over the years in yellow or in a dark green tone. The EE-9s carry their unit markings usually on the lower side plate between the front wheel and the boomerang suspension. The registration should not be confused with Brazil, Bolivia uses E.B.33-XXXX (with the XXXX seemingly ranging from 0101 to 0124), while the Brazilian Army used EB10-XXX or, more recently, EBXXXXX. Not all Bolivian EE-9s carry their registration however, which seem to have been lost in between repaintings.
A Bolivian EE-9 M2.
Source: Rodolfo Alberto Riascos Rodriguez
Bolivia has used their EE-9s mainly against protests as supposedly passive onlookers. One of these examples was when they were used against the Marcha por la Vida (March for Life) on August 21st 1986.
In an attempt to combat severe economic crisis and hyperinflation, the Bolivian Government enacted Decree 21060 in 1985. The Decree was a shock therapy for the Bolivian economy, adapting tariffs which caused prices to increase drastically, the dismissal of two thirds of the tin and oil company employees from government-managed companies, and the wage freeze of the other third until December 1985. It essentially meant liberalization of the market, removing restrictions on foreign trade which put local production under huge pressure and the end of foreign debt payment for a number of years.
Although the Decree managed to stop the hyperinflation, it also meant that more than 25,000 mine workers and the companies closed down, which in turn affected many other industries in the country. The overall effect of Decree 21060 was devastating for many households in the country. The protestors walked from Oruro to La Paz (the capital of Bolivia) from August 21st to August 29th 1986, until they were stopped and surrounded by the Bolivian Army which used EE-9s as passive onlookers.
In 2003, the EE-9 was used again during the Bolivian gas conflict. The conflict was a culmination of economic policies, coca eradication policies, corruption, and military suppression. The catalyst was a gas pipeline route to the Pacific Ocean which would have had to go through Chile in early 2002. Anti-Chilean sentiments were high, and Bolivians campaigned for the pipeline to go through Peru. In 2002, elected president Gonzalo Sánchez de Lozada expressed his preference for the Chilean option which resulted in heavy protests in the country. EE-9s were used in La Paz as guardians for the Government Palace and National Parliament and for blocking certain streets. The protests resulted in the resignation of President Gonzalo Sánchez de Lozada and around 60 protesters were killed, most of which in El Alto, where martial law was declared.
The Military Police supported by an EE-9 in La Paz.
Source: Rodolfo Alberto Riascos Rodriguez
Chile
The Chileans were perhaps the most interesting original EE-9 M2 buyers of them all. Chile was the only country to buy EE-9s with both the HS-90 turret and the ET-90 I turret and thus using two different 90 mm guns as well (D-921 and the EC-90). They received their first 60 vehicle EE-9 M2 batch with the HS-90 in 1976-1977 and received an additional batch of 23 EE-9 M2s with the ET-90 I in 1978-1979.
A Chilean EE-9 M2 with the HS-90 turret.
Source: Rodolfo Alberto Riascos Rodriguez
The conscript crews of these vehicles had to be rapidly trained as Chile and Argentina were on the brink of war over the Beagle Channel, known as the Beagle Conflict. These tensions rose so much that in 1978 an invasion by Argentina occurred for a few hours, but the impending war was stopped by an intervention from Pope John Paul II, who mediated the situation.
The Chilean EE-9s have received three different camouflage schemes. These include a single tone sand color, a three tone MERDC-style sand, black and dark green, and a three tone sand, dark green and brown. The Chilean EE-9s were retired from service around 1999-2000 and an unclear number of these EE-9s were sold to Israel at an equally unclear date. After modernization, Israel subsequently sold them to Myanmar with likewise vagueness.
A Chilean EE-9 M2 with the ET-90 I turret.
Source: Rodolfo Alberto Riascos Rodriguez
Libya
Libya was the largest operator of the EE-9 M2 and EE-9 M3, operating a total of 400 EE-9s, 200 of each model. The Libyan EE-9 M2s used the D-921 90 mm gun, the manual Clark transmission, and the OM352 engine, while the M3’s used an automatic AT-540 transmission, the OM352A engine, and was the first operator of the EC-90 armed ET-90 I turret. Libya was also the first country to use them in combat during the Four Day War of 1977 and the skirmishes preceding it.
Libyan EE-9 M3s.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
The Libyans continued to use them during the four Chadian-Libyan wars between 1978 and 1987 which culminated in the Toyota War of 1987 and a Chadian victory. During this string of conflicts, the Chadians are said to have captured around 60 EE-9 M2 and M3s from the Libyans. One of these EE-9 M2s ended up in the Saumur Tank Museum in France. The vehicle from Saumur was received in 1986, presumably captured by the French which fought on the Chadian side.
Libya would also donate or sell an unknown number of EE-9s to various international actors in Africa as part of a military diplomacy strategy. These include Burkina Faso, Congo, Ghana, Polisario Front (Sahrawi Organization in the Western Sahara), and Togo.
The most recent usage of the EE-9 in Libya was the Arab Spring and the resulting two civil wars in 2011 and from 2014 to 2020. Supposedly, a large number of EE-9s were in storage which are thought to have been looted during the civil wars. A number of EE-9s were operated by various movements in the country, with some turrets appearing to have been remounted on hulls of other models. A number of EE-9s with improvised side skirts have also been seen. An unknown number of EE-9s have also had their 90 mm guns removed, which were then mounted on pick-up trucks. These pick-ups are armed with both the D-921 and the EC-90 guns.
A Libyan EE-9 M3 with side skirts of the Al-Jazira Battalion
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
Other Operators:
Burkina Faso
Burkina Faso received an unknown amount of EE-9s from Libya. SIPRI (Stockholm International Peace Research Institute) lists two batches of 12 EE-9 Cascavels each for a total of 24 vehicles. These were supposedly delivered in 1983 and 1984. Very little is known about these vehicles and only a handful of pictures of these vehicles are known to exist. 3 EE-9 M2’s can be seen carrying out maneuvers in a video released by RTB.
Burkina Faso uses a four tone camouflage with sand, green, black and green as its tones. A small flag of Burkina Faso is also painted on the lower hull front, together with a registration. The two EE-9s that appear in the pictures do not have a laser rangefinder. The status of these EE-9s is unknown.
An EE-9 from Burkina Faso in 2006.
Source: Nairaland.com
Chad
Chad captured its EE-9s from Libya during the Chadian-Libyan wars from 1978 to 1987. Around 60 EE-9s M2 and M3s are said to have been captured and are, as far as is known, in storage. Some of the captured vehicles do have battle damage and most of them would need refurbishing to be put into service. To showcase Engesa’s business policy, from 1990 up to 1993, when the company faced bankruptcy, the company was in talks with Chad to effectively refurbish the captured EE-9s. In the end, the contract was never signed as Engesa went bankrupt in 1993.
The Chadian EE-9s may have seen combat during the Chadian-Libyan wars in Chadian service, but this is unknown as details of these conflicts remain limited. The Chadian EE-9s seem to have retained the camouflages from the Libyans, using single tone sand or two tone sand and green. It is possible that EE-9s were used during the Chadian civil wars and the Maghreb insurgency campaigns, but no information exists to support this.
Ex-Libyan EE-9s captured by Chad.
Source: Engesa EE-9 Cascavel 40 anos de combates 1977-2017
Democratic Republic of the Congo
The Democratic Republic of the Congo (DRC) seems to have received at least 3 EE-9s. Their origin is vague as they operate 1 EE-9 M3 which has the Libyan periscope layout, but the EE-9 M2s use 3 periscopes for the driver. It is possible that these were later acquired through perhaps Israel like Myanmar did, but this is speculation. When these were acquired and how many remain is unclear. The vehicles are painted in a dark green tone and their status is unknown.
2 EE-9 M2s from Congo, note the 3 periscope driver’s hatch layout.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
At least one EE-9 was used during protests of the 2006 general election. This was the first multiparty election in the country in 41 years. A significant number of protests took place before the election with fatal casualties as a result of fighting between the protestors and the Army. It is possible that the EE-9 was either used as a passive onlooker or to crack down on one of these protests. In the end, the election results remain somewhat questionable due to the events leading up and during the election. Joseph Kabila was voted in as president with 58% of the votes in the second election round (45% in the first) and the People’s Party for Reconstruction and Democracy won the parliamentary elections with 111 seats.
It is possible that the EE-9 saw service during the First and Second Congo wars, the Kivu and Ituri conflicts, and other conflicts or unrest inside the country ranging from 1996 to this day, but no sourcing proves this.
EE-9 M3 from DR Congo.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
France
France obtained a single EE-9 from the Libyans in 1986. If the vehicle was captured by the French or was provided by the Chadians is unclear. The French EE-9 is now located at the Saumur Museum. With the help of Hadrien Barthélemy, a contact with access to the vehicles, the writer has discovered that the first batch of Libyan EE-9s were actually M2s instead of M3s. In addition, the Museum provided documents on the date of the capture of their EE-9’s and interior pictures. The Saumur Museum has been tremendously helpful in uncovering new information on the EE-9 and the writer would like to thank the Museum for their help.
The EE-9 M2 at Saumur.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
Ghana
Ghana is or was an operator of which virtually nothing is known. All that is known is that they have at least a single EE-9 which seems to come from the Libyan batch. When they obtained them and how many is a mystery. The only known Ghanaian Army EE-9 uses a H-90 turret, which means that the hull is likely to be an M2 hull as well. It is painted with a three tone camouflage consisting of sand, black and a dark green. The EE-9 is seen loaded up in an Ilyushin IL-76 supposedly in 2011. No other pictures have been found. The EE-9 might have seen service during the First Libyan Civil War, the Sierra Leone Civil War, The First and Second Ivorian civil wars, the Mali War, the ECOWAS military Intervention in the Gambia, and the Western Togoland Rebellion, although nothing proves this.
The single known Ghanese EE-9 M2.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
Polisario Front
The Polisario Front is perhaps the most interesting group to receive EE-9s from Libya. This is because the Polisario Front is a liberation movement recognised for representing the Sahrawi people, the indigenous people of the Western Sahara. The Polisario Front was officially formed on May 10th 1973 in an attempt to drive out the Spanish from the Western Sahara.
Spain would cede the Western Sahara over to Mauritania and Morocco after the Madrid Accords, effectively causing the Polisario Front to fight both countries. After a coup d’etat in Mauritania in 1978, a peace treaty between the Polisario Front and Mauritania was signed in 1979 with Mauritania recognizing the Sahrawi Arab Democratic Republic and antagonizing Morocco. Morocco attempted to fully annex the region and a guerilla war rages to this day, with a ceasefire from 1991 to 2020 in between. Libya is thought to have supplied arms to the Polisario Front from around mid-1970 to mid-1980.
Among these weapons are an estimated 19 to 30 EE-9 Cascavels (19 according to Oryx and 30 according to Expedito Carlos Stephani Bastos). According to Oryx, these EE-9s were potentially delivered around the early 1980s. Based on the limited pictures available, at least 5 ex-Libyan EE-9 M2s were in service with the Polisario Front. These vehicles were painted in a single tone sand or in a two tone sand and dark green, with registration numbers on the turret sides. How many EE-9s remain in service is unknown.
EE-9 M2s of the Polisario Front.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
Myanmar
The acquisition of the EE-9 to Myanmar, like with other second-hand users, remains clouded with mystery. SIPRI estimates that 12 EE-9s were sold to Myanmar in 2007 and delivered around 2009-2010. The earliest date in Myanmar sourcing seems to be around 2011, which does somewhat seem to support the delivery date. A video of Saymar Ltd (the Israeli company which sold the EE-9 to Myanmar) showing an EE-9 appeared in 2008, with testing videos appearing in 2010 on YouTube which only further seems to support SIPRI’s data. The largest number of Cascavels in a single picture from Saymar and Myanmar total for 11 EE-9s.
EE-9s from Myanmar during a military parade on March 27th 2014.
Source: Brazilian Engesa EE-9 Cascavel 6×6 at War – Expedito Carlos Stephani Bastos
A Brazilian source however claims that 70 EE-9’s were bought from Chile in 2002. This might be possible considering Chile retired them, and it could be possible that this is actually the total number Saymar bought from Chile. It would then be the case that Saymar only managed to sell 12 EE-9s to Myanmar. No sale between Chile and Saymar shows up in SIPRI. There are claims that Mynanmar operates well over 100 EE-9s, but this seems unlikely considering Chile only owned 83 in total.
The Myanmarian EE-9s mainly received a refurbishment with some additional improvements. The original OM352A engine was replaced with an OM366LA 190 horsepower diesel engine, and the fire control system was optimized, including sights and electric turret and gun drives. In addition, the driver’s panel and overall electrics were revitalized and the brakes and suspension were refurbished as well. The refurbished and modernized EE-9s mainly present quality of life upgrades over the old models, but do not seem to be better than the later stages of the EE-9 development, like the EE-9 M4.
In addition, it seems that the Myanmarian EE-9s do not have a laser rangefinder unless they installed it internally in some way. The Myanmarian EE-9s appear to mount the Singaporean 12.7 mm STK 50MG machine gun in combination with a simple steel plate to provide cover for the commander. The EE-9s also appear to have received a stowage rack on the turret bustle, which was not standard on the H-90 turret.
The Cascavels from Myanmar were painted in dark green and received registration on the lower front plate and the turret sides, although the turret side registration does not appear on every Cascavel. The Cascavels are most likely, and seem to have been used based on pictures, against the many insurgencies plaguing the country over the course of the last two decades. They might also have been used during the 2021 coup d’etat and the subsequent resurgence of armed resistance by protestors against the new junta.
Togo
The Togolese Army received a number of EE-9s from Libya through exports. SIPIRI lists anywhere between 3 to 36 EE-9 Cascavels to have been delivered by Libya around 1982 to 1983. Based on a Latin America Report from 1985, Togo would have 5 to 6 EE-9s. In a newspaper entry from Togo from 1980, 5 platoons consisting of 3 vehicles each were said to have been created, consisting of the UR-416, the AML-90 and the EE-9. This would mean that Togo would have 5 EE-9’s in active service and either one or none in reserves.
The Togolese EE-9s may have been used during the First Ivorian Civil War, the Guinea-Bissau Civil War, the Mali War, and the ECOWAS military intervention in the Gambia. No proof exists of the EE-9s participation in any of these conflicts or even further proof of EE-9s in Togolese service exists.
The only known picture of the Togolese EE-9 M2s
Source: Rodolfo Alberto Riascos Rodriguez
Variants
The EE-9 M2 and M3 have had a significant number of variants built from them. A reason for this was because these were the oldest vehicles. Brazil essentially only sacrificed their EE-9 M2s for any prototype considering they were old. This has meant that the variants of the EE-9 M2 range from the very early days up to the present day with the latest EE-9 modernisation project being a conversion from an old M2 Cascavel.
There are a few exceptions in this list. The variants list will not comprise EE-9s armed with the H-90, ET-90 I, and ET-90 II turrets as these are already covered in the article. Any foreign variants will not be included if the upgrade was not carried out by Engesa as these variants are already covered in the sections from their respective countries.
EE-9 M2 SIMDABA
The EE-9 M2 SIMDABA was a prototype developed in 1998. SIMDABA stands for Sistema de Mísseis de Defesa Aérea de Baixa Altitude (Low Altitude Air Defence Missile System). The EE-9s turret was replaced with a system carrying two locally developed and produced Piranha MAA-1 anti-aircraft missiles. The vehicles would use the FILA fire control vehicle from Avibras as its operating system. The idea came from the AGSP and the PqRMnt/1 (Parque Regional de Manutenção da 1ª Região Militar, Regional Maintenance Park of the 1st Military Region) built the mock-up prototype.
The SIMDABA system was designed to provide quick and mobile air defense for important targets such as military columns, ports, airports, supply lines, and so on. As a result, the SIMDABA system was mounted on vehicles such as the EE-9 and the EE-11, but also on ships, trucks, and with towed anti-aircraft platforms. In the end, the project and the SIMDABA project more broadly seems to have gone nowhere.
The EE-9 M2 with the SIMBADA system mounted in place of the turret.
Source: Blindados no Brasil
EE-9 M2 QT Engenharia
The first modernisation program was proposed to the Brazilian Army by QT Engenharia e Equipamentos Ltda in 1995, 2 years after Engesa’s Bankruptcy. An EE-9 M2 and an EE-11 M2 were modernized by the company with the goal of modernizing as many vehicles in Brazil’s fleet as possible. QT Engenharia won the bid to modernize the two previously mentioned vehicles which were remnants from Engesa’s old stocks when they went bankrupt. The Cascavel received a new fire control system which used night vision and a laser rangefinder, with night vision blocks for the commander, driver and gunner. An automatic transmission was installed, considering the EE-9 M2 did not have access to one, and the drum brakes were replaced with disc brakes. A more powerful 280 hp engine was also considered. The project would have converted every Brazilian EE-9 to an improved version of the most advanced EE-9 Engesa offered until its bankruptcy, offering a more powerful engine than any EE-9 had at the time.The project was canceled in the late 1990s due to high costs.
The only available picture of the QT Engenharia upgrade proposals.
Source: Blindados no Brasil
EE-9 EQ-12
The EE-9U is the Army designation for the modernisation program of the Cascavel, which was initiated in the early 2010s. The company Equitron, which managed to acquire a number of the old companies supporting Engesa in producing components such as brakes, would help in the maintenance of a number of EE-9s by providing brand new components. With the success of this project, Equiton was invited to participate in the bidding process for the overhaul of an EE-9 M2 in 2013. Equitron secured the contract and the EE-9 M2 was delivered to them in mid-2014.
In 2015, the Brazilian Army opened another bidding for a modernized EE-9 which would again be secured by Equitron. The Equitron engineers initiated the design of a modernisation package which could be mounted on every Cascavel model of the Brazilian Army. The prototype was designated EQ-12 by Equitron, MX-8 by the AGSP, and EE-9U by the Army.
The engine was replaced with an OM906LA in-line diesel engine. The engine provided 264 hp at 2,200 rpm and 1,100 Nm at 1,600 rpm. The manual Clark transmission was replaced with a ZF 6HP 504C automatic transmission with 5 forward and one reverse gears. The ZF transmission was paired with a MB VG 550 Mercedes-Benz transfer case which offers a high and low gear option.
The main upgrade was to the fire control system. The Cascavel was outfitted with a optronics block on top of the gun, which offers thermals, a laser rangefinder, and laser illumination. In addition, 4 day/night cameras are positioned on each side of the vehicle for 360° view. The turret is outfitted with electric turret drives and the gun and turret are controlled with a joystick. All three crew members have access to a computer screen for vision and control of the systems, such as the gun. The integration of ATGMs on the turret sides was also considered.
The prototype was first tested at Marambaia Proving Grounds in the first half of 2016, with firing tests in October of the same year. The EE-9 modernization program then ended up being shelved for a while and was revived in 2021. Brazil was going to buy 8×8 Fire Support Vehicles, but it would need the Cascavel to remain in service until the deliveries were completed which was expected around 2040. Considering the EE-9 was almost 50 years old at this point, it was clear that it also needed to be modernized. A bidding for the contract was opened in February 2022, but was won by Akaer’s proposal.
Equitron’s proposal seems to have simply required too many structural changes to the vehicle which made it too expensive. Akaer’s proposal did not introduce these significant changes but kept it at the needed requirements to match the contract. As such, Akaer’s proposal is not as good, but is more affordable. In a way, it makes sense, as modernizing a 50 year old armored car as a stopgap should not cost a fortune.
The Brazilian companies Ares and Equitron presented a prototype for a TORC-30 armed EE-9 at the 2019 LAAD exposition. The turret was mounted on top of the original EE-9U prototype from Equitron as it shares the exact same registration. The TORC-30 was designed by Ares (a subsidiary from the Israeli company Elbit) and CTEx (Centro Tecnológico do Exército, Army Technology Center).
As the name suggests, the turret is armed with a stabilized 30 mm Rheinmetall MK30-2/ABM autocannon and can engage both ground and air targets. It has two magazines with 150 and 50 rounds each and a rate of fire of 600 rounds per minute. It can receive armor up to Stanag 4569 level 4 and anti-RPG capabilities. The turret has a hunter/killer and laser warning system combined with thermals and a high definition day camera.
The exact reason why the EE-9 with the TORC-30 was built remains somewhat uncertain. It was likely meant as a testbed for the turret and as a marketing opportunity. The EE-9 with TORC-30 could provide some additional anti-aircraft defenses, but it does not have the protection levels to serve as an infantry fighting vehicle, nor does the amount of ammunition seem to help in this regard. The Brazilian Army essentially concluded this already as far back in the 1970s, where it had recognised the inadequacy of an autocannon on the EE-9 platform as a ground combat vehicle, so the only opportunity would be anti-aircraft in the form of drone defense, for example.
The EE-9 with the TORC-30 and the REMAX RCWS on the turret top.
Source: Tecno & Defesa
Conclusion
The 90 mm armed EE-9 M2 was Engesa’s successful debut to the arms exporting industry. Although having a bit of a hitch because the Brazilian Army spent half a decade deciding what to arm it with, Portugal however, saw potential. Portugal liked the EE-9 platform, with its bimetal armor and Boomerang suspension offering excellent mobility and good protection for its weight, but disliked the 37 mm gun and wanted the 90 mm instead. This proved to be excellent advice, as Engesa would soon after sell 400 90 mm armed EE-9s to Libya in two batches and 107 more to Bolivia and Chile.
These sales and the supposed success of the EE-9 in service with Libya laid the foundations for the future success to build upon. The EE-9 M2 and M3 were still somewhat barebones with the manual transmission for the M2 and the headlights on top of the hull, but with the new funds, Engesa would redesign the turret and the headlights, in addition to offering improved drive components.
The M2 proved that a vehicle could be simple, cheap, effective, reliable, and use essentially heavy automotive/truck components to succeed. The early EE-9s not only provided the money so that Engesa could undertake increasingly ambitious projects, but also showed that a country making simple vehicles could turn into the 6th largest arms exporter with a market fixated on the so-called Third World. The 90 mm armed EE-9 M2 is essentially the vehicle that put the Brazilian arms industry on the map.
Brazilian EE-9 with ET-90 turret. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.EE-9 with ET-90 turret. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.EE-9 with HS-90 turret when it was paraded during the September 7th parada. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.Engesa’s EE-9 with HS-90 turret. Illustrations by the illustrious Godzilla funded by our Patreon Campaign.
Specifications (EE-9 M2 37 mm)
Dimensions (L-W-H)
6.22 m (with gun) x 2.59 m x 2.3 m (20.4 feet x 8.5 feet x 7.5 feet)
Total weight
11 tonnes (12.1 US tons)
Crew
3 (Driver, commander, gunner)
Propulsion
Mercedes OM352 or OM352A (125 and 172 hp)
Speed (road)
95 km/h (59 mph)
Operational range
750 km (466 miles)
Armament
90 mm DEFA D-921 (HS-90)
90 mm EC-90 (ET-90 I)
7.62 mm N model F-1 (Coaxial)
Armor
Hull Bimetal
Front 16 mm (0.63 inch)
Side 8 mm (0.32 inch)
Rear 8 mm (0.32 inch)
Top 6.5 mm (0.26 inch)
Floor 6.5 mm (0.26 inch) HS-90 Turret
Front 14-15 mm (0.6 inch)
Rear 7 to 8 mm (0.3 inch) ET-90 I turret
All-round 16 mm (0.63 inch)
Top 8 mm (0.32 inch)
Produced
464 M2s and 200 M3s
Special thanks to Expedito Carlos Stephani Bastos, the leading expert of Brazilian armored vehicles https://ecsbdefesa.com.br/, Jose Antonio Valls, an Ex-Engesa employee and expert in Engesa vehicles, Paulo Bastos, another leading expert of Brazilian Armored vehicles and the author of the book on Brazilian Stuarts and the website https://tecnodefesa.com.br, Adriano Santiago Garcia, a Captain in the Brazilian Army and ex-company commander on the Leopard 1 and ex-lecturer on the Brazilian Armored School, and Guilherme Travassus Silva, a Brazilian with whom I was able to endlessly discuss Brazilian Vehicles and who was always willing to listen to my near endless ability to talk about them.
Sources
Engesa EE-9 Cascavel 40 anos de combates 1977-2017 – Expedito Carlos Stephani Bastos
Ford M-8 Greyhound Exército Brasileiro – Surge o conceito de blindado 6×6 – Expedito Carlos Stephani Bastos
Blindados no Brasil – Expedito Carlos Stephani Bastos
Brazilian Stuart – M3, M3A1, X1, X1A2 and their Derivatives – Hélio Higuchi, Paulo Roberto
Bastos Jr., Reginaldo Bacchi
Engesa manuals
Equitron manual
Engesa brochures provided by Ed Francis http://www.lexicarbrasil.com.br/
Dual Harness skin stops armor-piercing projectiles Article of Richard M. Ogorkiewicz
Sipri Arms Transfer Database
Stuart: A history of the American Light Tank, Volume 1 – R.P. Hunnicutt
Armored Car: A history of American Wheeled Combat Vehicles – R.P. Hunnicutt
Juan Miguel Fuente Alba Poblete, Familia Acorazada del Ejército de Chile. Historia de los Vehículos Blindados del Ejército (1936-2009) (Santiago de Chile: Ejército de Chile, 2009)
Personal correspondence with Ex-Engesa Employees
Personal correspondence with Expedito Carlos Stephani Bastos
Personal correspondence with Paulo Roberto Bastos Jr.
Personal correspondence with Adriano Santiago Garcia
Federative Republic of Brazil (1971-1975/1976)
Reconnaissance Vehicle – At Least 9 Built + 102 Ordered
Up until 1967, Brazil was dependent on foreign countries for armored vehicles. Throughout and in the aftermath of World War 2, Brazil received large numbers of cheap surplus armored vehicles from the United States, including the M3 Stuart and the M4 Sherman, as it had entered the war on the Allied’s side in 1942. In fact, Brazil had not undertaken any tank design since 1932, and those had only been conversions of tractors and cars into armored vehicles during the revolutions of 1924, 1930, and 1932.
Between 1932 and 1958, the Brazilian Armed Forces created a solid basis of technical institutes from which it could educate technical and research personnel. In turn, these helped the Brazilian automotive industry in developing its own automotive parts and helped in opening laboratories for the manufacturers. In 1967, Brazil set up a plan for the country to become more militarily self-sustaining. The flow of US material had decreased because of its entanglement in the Vietnam War and, after a study, Brazil recognised external dependence on arms suppliers as a serious problem for its political position in South America.
The plan to solve this became the start of the Brazilian defense industry. After the Army had remotorised various vehicles, such as the M8 Greyhound, with diesel engines, they set off developing Brazil’s first wheeled vehicle with serial production in mind. The 4 x 4 VBB-1 which resulted from this development was everything but revolutionary. It did provide the needed experience and confidence for the Brazilian engineers though. With the rejection of the VBB-1 because the Army wanted a 6 x 6 vehicle, Brazilian engineers started developing the vehicle which would become the most successful armored fighting vehicle Brazil ever developed: the EE-9 Cascavel.
The story of why the EE-9 Cascavel (English: Rattlesnake) was developed can be traced back to the Second World War. Brazil sent an expeditionary force, known as the Smoking Snakes, to fight in Italy alongside the Allies. During the Italian Campaign, the Brazilian forces were armed with US M8 Greyhounds. The M8 Greyhound turned into the most loved vehicle by the Brazilian soldiers, and after WW2, this love would remain embedded in the Brazilian Army. The positive experience with the M8 during WW2 caused it to be the most impactful vehicle for the Brazilian development of armored vehicles. As a result, most of the wheeled vehicles and the wheeled vehicle program can trace back their roots to the M8 Greyhound during the Italian campaign. This love for the M8 resulted in the development of Brazil’s EE-9 Cascavel some 25 years after WW2, a heavily improved and altered concept of the M8 Greyhound.
Although Brazil enjoyed its diplomatic relations with the United States well into the 1970s, the first steps to break free from the United States, from an Army materiel point of view, started in 1967. The United States got increasingly involved with the Vietnam War and, as a result, could not supply Brazil with the cheap equipment it once did. This severely undermined Brazil’s political power in South America. Not only were they seen as a United States proxy state, now with the military ties effectively cut loose, Brazil had no way to fight a prolonged war with its neighbors.
The Brazilian Army conducted a study regarding its dependency on the United States in 1967, which resulted in the Triennial Plan 68/70. The Brazilian Army recognized its external dependence as a serious issue and advocated for the encouragement of R&D (Research and Development) of locally designed and produced materiel. This would in turn cause the Diretoria General de Material Bélico (DGMB) (English: General Directorate of War Material) to further study armored equipment from all over the globe, with 4 x 4 and 6 x 6 vehicles in particular. By studying the wheeled vehicles of the United States, the United Kingdom, Belgium, Switzerland, the Netherlands, and Italy at the time, the DGMB called for the intensive adoption of wheeled armored vehicles. These vehicles required a relatively modest investment for their development, and as such, were more viable to develop instead of importing them. The study proposed the creation and adoption of a vehicle like the M8 Greyhound, but simpler.
PqRMM/2
From this point onward, the Parque Regional de Motomecanização da 2a Região Militar (PqRMM/2) (English: Regional Motomecanization Park of the 2nd Military Region) started taking the first steps towards developing armored vehicles for the Army. The PqRMM/2 was a group of army automotive engineers gathered to study, develop and produce armored vehicles in Brazil, and were the pioneers of the Brazilian defense industry.
The first step the PqRMM/2 team undertook was the motorization of Brazil’s M8 Greyhounds and M2 half-tracks with locally produced diesel engines. With the success of these projects, they continued to the next phase of the program and developed Brazil’s first wheeled vehicle with serial production in mind. The Viatura Blindada Brasileira 1 (VBB-1) (English: Armored Car of Brazil 1) was a 4 x 4 vehicle meant for reconnaissance and mounted a copy of the M8 Greyhound turret. The VBB-1’s concept came from the Belgian FN 4RM 62F, but its design was based on the M8 Greyhound. Although the VBB-1 seems to have successfully performed its tests when the vehicle was presented to the Army in 1969, the Army did not want a 4 x 4. It was briefly considered by the engineers to cut the hull in half and lengthen it to accommodate a 6 x 6 suspension, but the idea was almost immediately rejected, as the development of a new vehicle was deemed more effective.
Why the PqRMM/2 engineers developed a 4 x 4 for the Army in the first place is a bit strange, considering they knew that the army wanted a 6 x 6 like the M8 Greyhound. Nevertheless, the VBB-1 would lay the groundwork for the research of the 6 x 6 vehicle. Some components were carried over from the VBB-1 to the upcoming 6 x 6, such as the turret and engine. By starting from scratch, the team could implement all the lessons they learned from the VBB-1 project and thus get a better basis for future developments.
The VBB-1, note the influence of the M8 Greyhound like the turret.. Source: Blindados no Brasil
The VBR-2
For the development of the Viatura Blindada de Reconhecimento 2 (VBR-2) (English: Armored Reconnaissance Vehicle), the PqRMM/2 team followed the specifications of the Diretoria de Motomecanização (DM) (English: Directorate of Motomechanisation). The VBR-2 was pretty much a Brazilian copy of the M8 Greyhound. A single metal mock-up of the VBR-2 was made by the PqRMM/2 in early 1970.
Its overall shape was almost identical to the M8, with the raised hull construction for the driver being one of the most notable features. The hull construction was a bit more simplified though, with more flat plates like the VBB-1, but without some of the complicated shapes of the VBB-1. It mounted the same turret as the VBB-1, which was a copied M8 Greyhound turret but with a closed top. It was armed with a 37 mm cannon and a .50 cal machine gun.
The engine deck style also resembled the M8’s and came from the VBB-1 design as well. Considering the overall design features, it can be expected that the rear of the VBR-2 would also look like the M8, considering the VBB-1 and the later EE-9 Cascavel rear all share the same design.
The VBR-2 mock-up underwent various redesigns together with a redesignation to Carro de Reconhecimento sobre Rodas (CRR) (English: Wheeled Reconnaissance vehicle). The hull underwent some geometric redesigning, causing the vehicle to look less like a box because of the more angled side plates. Another difference in the hull design, which enabled the hull to receive an improved ergonomic design, was the redesign of the driver’s raised hull construction.
The VBR-2 had a raised construction that extended towards both sides of the hull to provide vision for both the driver and co-driver much like the M8 Greyhound. The raised hull construction was now located in the middle of the hull on the CRR and did not extend to both sides of the hull. This meant that the CRR did not have a co-driver, which reduced the crew to 3.
Another important step in the development of the CRR was the installation of the Boomerang suspension from Engenheiros Especializados SA, better known as Engesa. Engesa had previously modernized and delivered new trucks for the Brazilian Army with their Total Traction system. This patented traction system was the key for Engesa in the defense industry, mainly because it was identified as a system ‘of interest to National Security’ by the Army. Engesa also participated in the VBB-1 project by supplying the transfer box. With the VBR-2 built, the PqRMM/2 team sought a better suspension system for the 6 x 6 vehicle and found it in an invention from 1969.
The CRR during construction. Source: Ford M-8 Greyhound no Exército Brasileiro – Expedito Carlos Stephani Bastos
The Boomerang Suspension
In 1969, Engesa invented the Boomerang suspension. The suspension was invented to enable trucks to transport oil from difficult terrain with bad infrastructure to the refineries. With this suspension, the trucks could traverse otherwise untraversable hills for conventional suspension systems, as the wheels would always stay in contact with the ground to provide maximum traction.
An EE-9 M2 showing the boomerang suspension. Source: Engesa Brochure
The suspension system was a two wheeled-single axle driven suspension. The advantage of the boomerang suspension was that it could be fitted on existing differentials with a single axle. Normally, this meant that the single axle, designed for the torsion forces of a single wheel, was subjected to the torsion forces of two wheels. Through excellent engineering, half of the torsion forces of the two wheels were mitigated by the suspension system built around the original axle. This design not only enables the drive of two wheels by a single axle but with clever usage of gears and bearings on both the axle and tube around the axle, the suspension system can rotate around its axle for 360 degrees. This ability to rotate in extreme angles would enable the vehicles to traverse very difficult terrains and still provide maximum traction, as the suspension system curved with the terrain so that all the wheels were always in contact with the ground.
The boomerang suspension. Source: Engesa manual
Engesa
Engenheiros Especializados SA, or Engesa, was the largest and the most famous company in the Brazilian armored vehicle industry. Engesa was founded in São Paulo in 1958 by José Luiz Whitaker Ribeiro. Initially, Engesa focused on oil prospecting, production, and refinement equipment. With the invention of Engesa’s total traction suspension system, they were hired to modernise and build trucks for the Brazilian Army.
In 1969, Engesa introduced its flagship boomerang suspension for its wheeled vehicles. Only a single axle was needed to drive the 4 wheels which were in constant contact with the ground, providing constant traction. At the time, this was a simple, sturdy, and relatively cheap construction. Although not fit for heavy vehicles, it was perfect for the armored vehicles that Engesa would start to manufacture in the near future.
With Engesa’s involvement in refitting the Army’s trucks with the Total Traction system and the development of their Boomerang suspension, they were contacted by the Army to help develop the wheeled vehicles together with the PqRMM/2 team. This joint development resulted in the EE-9 Cascavel and the EE-11 Urutu. The EE-9 Cascavel paved the way for Engesa to take its position as the leading company of the Brazilian Defense Industry.
With the installation of the boomerang suspension and the redesign of the hull, the basis was laid for what would become the EE-9 Cascavel. The mock-up of the CRR was built in early 1970 and presented to General Plínio Pitaluga, a veteran of the FEB. It seems that, almost immediately after the mock-up was finished, the PqRMM/2 engineers started the production of the first working prototype.
Nearing the end of the construction of the CRR prototype, a new turret was developed for the new 6 x 6 vehicle. The CRR mounted a redesigned VBB-1 turret with a turret bustle. The VBB-1 turret was a copy of the M8 Greyhound turret and was manufactured by Fundições Alliperti S/A and Avanzi. It is noted that the redesigned VBB-1 turret was manufactured by Companhia Siderúrgica Nacional (CSN) (English: National Steel Company). Although the CRR received the redesigned VBB-1 turret, the original plan was to mount copied and redesigned M3 Stuart turrets with an added turret bustle, which were also produced by CSN. But, by the time the CRR prototype was finished, the redesigned M3 Stuart turrets were not ready yet.
The finished prototype of the CRR with the VBB-1 turret and boomerang suspension. Source: Ford M-8 Greyhound no Exército Brasileiro – Expedito Carlos Stephani Bastos
The prototype of the CRR was completed in 1971. It used a copied and redesigned M8 turret armed with a 37 mm cannon and a .50 machine gun on top of the turret. The turret was a fully enclosed turret designed by Engesa. The vehicle-mounted run-flat tires were previously developed by Novatracão for the VBB-1 project. The vehicle’s exhaust was located on the right side of the rear. The vehicle had a crew of 3. The driver was positioned in the middle of the hull and had a raised structure for his head and the sights. The remaining two crew members were the gunner and the commander/loader.
The CRR. Source: Engesa brochure
The CRR was extensively tested by the Brazilian Army, tests which were overseen by the PqRMM/2. During the tests, the CRR prototype travelled over 65,000 kilometers and performed various mobility tests. The tests were successful, as the construction of a 5 vehicle pre-series was approved. The number of pre-series vehicles would increase to a total of 8 vehicles after the Diretoria de Pesquisa e Ensino Técnico do Exército (DPET) (English: Army Directorate of Research and Technical Education), which oversaw the PqRMM/2 developments, signed a contract with Engesa in June 1971 for the development and construction of the pre-series. Production of the 8 pre-series vehicles for the Brazilian Army began in 1972 and was finalized in September 1975.
The Finished CRR with the redesigned M8 turret on the right, and the CTRA (Carro de Transporte sobre Rodas Anfíbio, English: Wheeled Amphibious Troop Transport), a predecessor of the EE-11 Urutu, on the left. Source: Engesa Brochure
With the signing of this contract, the CRR was officially carried over to Engesa. What is interesting is that the Brazilian Army, despite having developed the CRR, signed off all their intellectual property rights to Engesa. This effectively meant that the Brazilian Army itself would not directly profit from any sales of the future EE-9 Cascavel to other countries. This transfer to Engesa also meant that the CRR would be marketed as the EE-9 Cascavel.
The CRR during trials. Source: Ford M-8 Greyhound no Exército Brasileiro – Expedito Carlos Stephani Bastos
The Snake Family
The EE-9 Cascavel was part of a family of wheeled vehicles, all named after snakes found in Brazil. These vehicles were the EE-3 Jararaca, EE-9 Cascavel, EE-11 Urutu, and EE-17/18 Sucuri, meaning jararaca, rattlesnake, crossed pit viper, and anaconda, respectively.
The EE-3 was a 4 x 4 reconnaissance vehicle that could mount a wide range of turrets. The EE-9 was Engesa’s reconnaissance vehicle, but due to its mobility and the 90 mm cannon, it would be employed in all kinds of roles. The EE-11 was a troop transport but could be configured to perform all sorts of specialised roles, like Anti-Aircraft, mortar carrier, and ambulance. The EE-17 and EE-18 Sucuri were two 105 mm armed 6 x 6 wheeled tank destroyers.
Logos of Engesa’s Snake family. Source: Blindados no Brasil – Expedito Carlos Stephani Bastos
The EE-9 was effectively the flagship of this family, even though Engesa thought the EE-11 would be their most successful vehicle. The EE-11 was successful nevertheless, but the Jararaca and the Sucuri were less of a success. The Jararaca was sold in very limited numbers, while the Sucuri was not even sold at all.
With the transfer of the CRR to Engesa also came a new designation. The exact date of when the CRR was designated as EE-9 is unknown. But it is estimated to have been named EE-9 between 1972 and 1973, with EE referring to Engenheiros Especializados (English: Specialized Engineers) and the 9 to its weight in tonnes. The interesting part is that practically every Cascavel exported by Engesa weighed more than 10 tonnes empty. As such, the 9 in EE-9 refers to the 37 mm version of the Cascavel. The weight in a brochure, which is estimated to have been written between 1973 and 1974, refers to the Cascavel with a 37 mm gun as having a 9 tonnes combat weight.
The CRR was redesignated by the Army as well, with the completion of the pre-production batch, to Carro de Reconhecimento Médio (CRM) (English: Medium Reconnaissance Car). This designation is more of a vehicle classification, like the CRR, than a name. This effectively means that the prototype CRR, the pre-production CRM, and the production vehicles were all known and sold as EE-9’s.
What is interesting, is that Engesa seems to have skipped designating an M1 Cascavel, and immediately built M2 hulls after the CRM. It might be that the 37 mm Cascavels were unofficially seen as first production versions, but through hull classification were simply branded as M2’s.
Since the EE-9 Cascavel was built and developed for 18 years, it received upgrades and design changes over time. To keep track of these changes, a so-called Modelo or Model system was used. It is important to note that different guns or turrets did not mean that the Cascavel was a different model. The Cascavel M2 for example, used all three 90 mm turrets offered by Engesa (HS-90 turret with the French D-921 gun, ET-90 I turret with EC-90 gun, and the ET-90 II turret with EC-90 gun). It was mainly changes to the hull, and especially the transmissions, which caused the Cascavels (Portuguese: Cascavéis) to be classified as a certain model. The Modelos were then further subdivided in production batches or Séries. The differences between the series could be as small as different bolts or different tyre nozzles. The development of the Cascavel was a process of evolution, and certain manuals would be written specifically for a range of series of a certain model.
The enthusiast’s guide to Engesa’s Cascavel galaxy
Model
Charatistics
Date
Sold numbers by Engesa
CRM
The pre-production EE-9 with a manual Clark 280V transmission and a 37 mm gun, practically an improved M8 Greyhound.
1971
8
EE-9 M2
Interestingly, Engesa seems to have skipped designating a Cascavel with the M1 designation. As a result, the production Cascavels with 37 mm guns are also M2’s.
The first EE-9 to have a 90 mm gun as its main armament. Overall hull redesign, larger dimensions of the hull to mount the new 90 mm armed turrets. Used a manual Clark 280V Transmission
1974
Brazil: 157 of which at least 9 were originally armed with 37 mm.
Bolivia: 24
Chile: 83
Libya: 200
EE-9 M3
Effectively an M2 Cascavel, but with an automatic MT-540 transmission (the first Cascavel model with an automatic transmission). The first Cascavel model to receive the EC-90 gun.
1975
Libya: 200
EE-9 M4
The M4 was specifically designed, built and sold with the Detroit Diesel 6V53 engine. Overall strengthening of components and further evolution of the hull design. It used an MT-643 transmission.
1979
Brazil (CFN): 6
Colombia: 128
Cyprus: 124
Iraq: 364
EE-9 M5
Used the M4 design but was a cheaper version. It was sold with either an AT-540 or AT-545 transmission in combination with the OM-352A engine.
1981
Bovington Tank Museum: 1
Gabon: 14
Uruguay: 15
EE-9 M6
Automotive enhancements over the previous models. Used the AT-545 in combination with the OM-352A engine.
1982
Brazil: 37
EE-9 M7
The same as the M6, but used an MT643 transmission. This Cascavel was the final model designed by Engesa. It could mount every engine which Engesa sold with the Cascavel, although it only seems to have been used with the OM-352 and the OM352A engines.
Total: around 1,742 sold and less than 1,800 produced.
Arming the EE-9 Cascavel
In 1972, with the start of the construction of the pre-production Cascavels, came the discussion of what the future reconnaissance vehicles of the Brazilian Army should be armed with. Up until then, the reconnaissance doctrine of the Brazilian Army had not changed since their experiences in World War 2, and this old doctrine was still somewhat ingrained in the Army.
An analysis regarding the specifications for a reconnaissance vehicle was released on July 10th 1967. The requirements called for a vehicle which could penetrate its own armor at ranges up to 1,000 meters, fire in all directions (have a turret), a rate of fire of at least 3 shots per minute, and the armament did not have to be used for anti-air purposes. The issue with these requirements is that practically every gun of 20 mm and higher could perform this job.
With the initiation of the VBR-2 project, a discussion emerged within the Army. Recommendations were gathered on what to arm the coming generation of reconnaissance vehicles. The issue was that the Armies (plural) of Brazil, generals, and departments gave conflicting advice about what to arm the vehicle with. Aside from this, the Army also had to take export potential into consideration for Engesa. Since the Brazilian Army completely handed over the project to Engesa, they also wanted to keep logistics and profit for the company as advantageous as possible. By the end of 1972, the Brazilian Army had selected two ranges of potential cannons: 20 to 40 mm or the 90 mm. The Army referred to the FV107 Scimitar for the lower caliber cannons, potentially suggesting that they wanted an autocannon on the Cascavel, and not the 37 mm which they had used so far.
With the selection of the two ranges, a new discussion came at the forefront regarding the purpose of the reconnaissance vehicle. It was recognized that less than 4% of the missions performed by cavalry units during World War 2 were pure reconnaissance missions. The question then was which role would the future Cascavel perform the most and which of these guns was the most suitable. The 90 mm would perform best for anti-tank missions, while the 20 to 40 mm range would be more fit against personnel and overall perform an infantry fighting vehicle role, without being able to carry infantry. It was identified that the EE-9 would not be fit to fill the Infantry Fighting Vehicle role as it did not have the armor to reliably perform this role. At the same time, it was recognized that a 90 mm gun would give the Cascavel a better fighting chance against potential enemy armor. The reasoning was mainly from an isolation point of view, in which a Cascavel on a reconnaissance mission had to fend for itself and take out potential enemies, like tanks. It was determined that the 90 mm was the most suited for this role, considering most of Brazil’s neighbours operated the Shermans as their heaviest armored vehicles at the time, and employed a large number of AMX-13’s and SK-105’s as their other combat tank.
It took up to the second half of the 1970s for the Brazilian Army to completely make up its mind on which cannons should be used on the Cascavel. When this discussion still raged in 1977, the Cascavel with 90 mm gun was already used by Libya against Egypt, and multiple countries ordered the 90 mm cannon.
What might have steered the Brazilians towards eventually deciding to operate a 90 mm Cascavel only force were the trials in Portugal in 1973. Portugal was still in the War of Ultramar as it tried to maintain its colonial empire. Among the vehicles the Portuguese used to fight their opponents was the AML-90. The AML-90 was a 4 x 4 armored car which could be used for reconnaissance and was armed with the potent D-921 90 mm gun.
An AML-90. Source: https://www.super-hobby.nl/products/Panhard-AML-90-Reconessance-vehicle.html
The Portuguese were approving of the EE-9 Cascavel, which boasted better mobility than their AMLs, but suggested that Engesa should retrial the vehicle when it was armed with the French D-921 gun. As a result, the Brazilian Army ordered the turrets and guns for both the single EE-9 of Engesa and the X1 tank program as well. Engesa retrialled the EE-9 in early 1974, but would not manage to sell the vehicle, as the Portuguese government was overthrown and the War of Ultramar ended. The Engesa team decided to pack up their vehicles and head straight to Libya, where they managed to secure a deal for 200 EE-9 Cascavels armed with 90 mm guns.
From this point on, an increasing number of countries started ordering the 90 mm Cascavel, and it is thought that the popularity of the 90 mm gun, in combination with the performance of the 90 mm gun, caused the Brazilian Army to finally opt for the 90 mm armed Cascavel.
Armoring the EE-9 Cascavel
Until 1968, armor studies were practically non-existent in Brazil. There had been some brief attempts during the revolutions of 1924, 1930, and 1932, but these were mainly of improvised nature. With the initiation of national armored vehicle development also came studies on what to armor the upcoming armored vehicles with. The PqRMM/2 team started off by evaluating all the steel compositions of the vehicles which were acquired by the Brazilian Army over time. The team discovered that the homogenous steel plate of the M2 Half-Track had been heat-treated on the outer side to provide a harder surface, while providing a more ductile surface on the inside to prevent shattering.
The team determined that the effort needed to carry out the necessary techniques for hardening was only justifiable for mass production. With mass-production of the future armored vehicles being expected, the team decided that the development of a dual-hardness plate or bimetal armor would be viable. This type of steel was previously developed in Sweden in 1930 and was known as duplex steel. It would find its first extensive usage on armored vehicles in Brazil. The main difference from other examples of face hardened armor is that two plates of varying carbon content were welded together in production to form a bimetal plate instead of bolting on a hardened plate afterward.
The steel for the bimetal plates was provided by Eletrometal and Usiminas. With Eletrometal providing the high-carbon outer plates and Usiminas the medium-carbon plates. The plates were joined, with 25% of the total plate thickness being high-carbon steel and 75% medium-carbon. The plates were laid on top of each other and subsequently welded around the edges. The bimetal plates were then forged together from 65 mm to about 30 mm thickness and then hot-rolled to the required thickness, This was followed by a quench, tempering, and hardening to the desired hardness. The high-carbon plate was hardened to 700 Brinell while the medium-carbon plate was 250 Brinell.
The average effectiveness of the bimetal plates was about 1.8 times the thickness of an equivalent homogeneous plate against 7.62 mm or 1.5 times the thickness against .50 machine gunfire. This meant that, against .50 machine gun fire, a 16 mm bimetal plate could be used instead of a 25 mm homogenous steel plate. These protection advantages over homogenous plates effectively meant that the Cascavel saved a lot of weight without compromising protection. The outer layer would shatter and blunt the incoming projectile, while the inner layer would relatively move with the bullet, slowing it down and stopping it without shattering.
An interesting tidbit of information according to an ex-Engesa employee who worked at the tempering station was that, at some point, the armor did not perform according to standards. It turned out that the tempering oven was not maintained properly, and the temperature control was faulty. This issue would remain for a few years until it was finally resolved. In order to keep building the armored vehicles, a lot of these plates were approved by quality check anyway, despite being faulty.
Trials in Portugal
In early 1973, Engesa trialled their vehicle in Portugal in an attempt to export it. As previously mentioned, Portugal was fighting against its uprising colonies in the War of Ultramar, also known as the Overseas War in English. At the time, the Portuguese Army was operating a mix of AML-90 and Panhard EBR armored cars in Africa. The Portuguese were impressed by the EE-9 Cascavel, which at that time was most likely still in its CRR configuration, but they suggested that Engesa should arm the Cascavel with the same turret and gun as the AML-90 and return to trial the vehicle again.
With Engesa wanting to arm the Cascavel with a 90 mm gun, the Brazilian Army opted to go for the 90 mm gun on the X1 project as well. They bought 53 turrets and guns from the French company SOFMA. Most of these turrets were ditched, as they did not meet the protection requirements of the Brazilian Army, and local turrets were designed and built as a result. Engesa would arm the EE-9 sent to Portugal with the French turret, but also developed their own turret.
The EE-9, most likely with the M2 hull design to solve some practical issues of the CRR configuration, and mounting an HS-90 turret and armed with a D-921 90 mm gun, was trialed again in early 1974. This EE-9 trialed in Portugal could be counted as being the first 90 mm armed EE-9 M2 Cascavel. The problem is that these designs were made before the later production variant of the EE-9 was known to have been built around 1975. For this reason, these projects will be seen as prototypes for both the 90 mm armed EE-9 M2, because of its armament, and as prototypes for the 37 mm EE-9 M2 because of the likely redesigned hull. Portugal would not acquire the EE-9 M2 because a Coup d’Etat put an end to the War of Ultramar.
The influence of Portugal in the success of the EE-9 should not be understated. After the failed attempt to sell the EE-9 Cascavel to the Portuguese, the Engesa team loaded the Cascavel and Urutu back in their freighter and set course to Libya. There, the EE-9 M2 would find success and manage to secure a deal for 200 Cascavels. This deal brought the necessary cash for Engesa to buy a large production plant, and by 1975, the first production Cascavels started rolling from the production line.
The request of the Portuguese to arm the EE-9 with a 90 mm gun effectively helped Engesa to secure a deal with Libya, which would eventually use the Cascavel in combat, generating more sales and making the Cascavel the success it was. At the same time, Brazil also started the development of locally produced turrets for the 90 mm guns for both the Cascavel and X1.
90 mm Turret Designs on the CRR hull
The switch from 37 mm towards the 90 mm would normally mean that the EE-9 Cascavel is an EE-9 M2. These projects were specifically designed on the early CRR hull or on a hybrid between the CRR and the pre-production vehicle which would be designated as Carro de Reconhecimento Médio (CRM) (English: Medium Reconnaissance Car). The problem is that these designs were made before the production vehicle of the EE-9 was built. For this reason, these projects will be seen as prototypes for both the EE-9 M2, because of their armament, and as prototypes for the 37 mm armed EE-9 M2, because of the hull. There were two designs: a CRR/CRM hybrid mounting the copied and lengthened M8 turret and armed with a 90 mm gun and a CRR with the French turret.
The CRR with HS-90 turret
The Brazilians made a design with the CRR hull mounting an HS-90 turret. This design was effectively the predecessor of the EE-9 M2 Cascavel. The HS-90 turret was ordered from France and had to be bought as a full package, including the D-921 gun. This Cascavel would have had a gun depression of 8 degrees and an elevation of 15 degrees. Aside from the 90 mm gun, it was also armed with a coaxial 7.62 machine gun. In addition to its armament, it would also be armed with 3 smoke launchers on each rear side of the turret. It could mount a turret top machine gun, night vision sights, radio and intercom, laser rangefinder, and an extra ammunition stowage as optional equipment. It is stated that the EE-9 sent to Portugal used this turret, but it is unlikely that the CRR hull was used for these trials.
The CRR with a HS-90 turret. Source: Engesa brochure
The reason for this is that the HS-90 turret would not only be too big for the hull and come in collision with both the driver’s vision structure, but also with the engine bay covers. On top of that, the driver’s vision structure would make it virtually impossible to depress or even fire the gun on a flat angle. As such, it seems that the drive for the 90 mm turret caused the hull to be redesigned to resolve these issues.
A sketch detailing the collision issues of the HS-90 turret on the CRR hull. Done by Godzilla.
The CRR/CRM Hybrid M8 Copy Turret
Another of the designs was effectively a hybrid between the CRR and the later CRM production vehicle. The main hull design change which hints towards it being a hybrid design is the altered headlight guard. On the CRR, the headlight guard was a simple square design, while in this design, it was curved, like on the CRM.
In addition, the copied M8 turret also received some changes which would be seen in the turret later used on the pre-production CRM. Compared to the original CRR turret, this turret had a ventilation inlet on the top of the turret and the antenna, which was originally on the left rear side of the hull, has now been installed on the turret as well. Apart from these 2 features, the turret also provided periscopes for the gunner, apart from the direct sight in the gun mantlet. The 90 mm gun would have a depression of 8 degrees and an elevation of 13 degrees and be installed in a turret with a turret diameter of 1.6 meter. It could mount a turret-top machine gun for anti-aircraft purposes.
In addition, a Perkins type 6357 6 cylinders in-line 142 hp diesel engine, along with a Chrysler type 318 HD V8 196 hp diesel engine, were offered. But Engesa also offered to fit in other engines, depending on the customer’s needs. It would use a 6-speed manual gearbox with five speeds forward and one in reverse. It would have been protected from the front with bimetal armor, protecting against .50 machine gun fire and from the sides from 7.62 mm fire. The exact weight and speed of this design are unknown but are estimated at around 10 to 11 tonnes and 95 km/h, depending on the engine selected.
The CRR with the redesigned M8 turret, armed with a D-921 90 mm gun. Source: Engesa brochure
The CRM
By September 1975, the production of the pre-series of 8 vehicles, known as the CRM, was finished. The pre-series hulls still carried over much of the design of the CRR hulls. The CRM can be easily identified and distinguished from the CRR in two ways. The first is the redesigned headlight guards, which were now curved instead of simple squares. The second is the relocation of the antenna and most likely the radio set as well. On the CRR, the antenna is located on the left rear of the hull, while on the CRM, the antenna was moved to the turret.
The CRR on the left with the simple square headlight guards and the antenna on the hull, and the CRM on the right with the redesigned headlight guards and without an antenna on the hull. Source: https://pt.wikipedia.org/wiki/EE-9_Cascavel#/media/Ficheiro:Cascavel1.jpg and Ford M-8 Greyhound no Exército Brasileiro – Expedito Carlos Stephani Bastos
When the CRM was delivered, it seems that the planned altered M3 Stuart copy turrets were still not finished. As a result, the CRM received a much more modernized version of the original CRR turret. The new turret incorporated a ventilation inlet on the left rear of the turret top with the antenna and, most likely, the radio sets moved next to it on the right side. The turret structure on both the commander’s and gunner’s side was also much improved compared to the CRR. A structure was welded on both sides which integrated 2 extra sights to enable a much better overview for the crew.
The CRM, note the added construction on the sides and the redesigned headlight guards. Source: https://pt.wikipedia.org/wiki/EE-9_Cascavel#/media/Ficheiro:Cascavel1.jpg
The 8 vehicles were almost immediately tested after they were delivered. They had to drive back and forth for 32,000 kilometers between São Paulo to Alegrete. The CRM’s drivo 24/7 and only stop for fuel or if maintenance was needed. The CRM’s seemed to have performed well during these trials, as the CRM, and thus the EE-9 Cascavel, was accepted into service. 102 production vehicles were ordered by the Brazilian Army, all armed with the 37 mm gun.
A Bid for a National Turret
It seems that, around this time, a bid was opened by the Brazilian Army for a locally designed and produced turret to be mounted on the EE-9 Cascavel. Interestingly, of the pictures available, Bernardini built a turret with a 37 mm cannon, while Engesa had the turret with a 90 mm gun which was originally mounted on the X1 prototype. It is very likely that Bernardini also offered the 90 mm turret, as the 37 mm turret was effectively the production turret of the X1, but rearmed with a 37 mm cannon. It is unknown if Engesa built and offered a 37 mm turret. Both of these proposals were built on CRM hulls.
Bernardini’s Entry
As previously stated, Bernardini would have most likely entered the competition with both the 37 mm turret and the 90 mm turret. The turret which Bernardini offered was the production turret of the X1, which was designated BT-90A1. The Brazilian Army had previously bought 53 HS-90 turrets and D-921 90 mm guns. The issue was that the turret armor of the HS-90 was insufficient for the requirements of the Centro de Pesquisa e Desenvolvimento de Blindados (CPDB) (English: Center for the Research and Development of Tanks). As a result, Bernardini and the Brazilian Army started developing a local turret that was armored with 25 mm thick plates to protect the X1 from .50 cal machine gunfire. The design of the BT-90A1 turret was heavily inspired by the HS-90 turret, with the first prototype of the turret (BT-90) even using some components of the HS-90 turret. The main differences between the HS-90 and the BT-90A1 were the addition of a gun shield on the BT-90A1, improved armor, and the BT-90A1 overall being more bulky than the HS-90. The main difference between the 37 mm and the 90 mm turrets from Bernardini was that the 37 mm turret received a new gun shield and was altered for the 37 mm armament.
Engesa’s design was the turret which was briefly mounted on the X1 prototype. The turrets differed in a very minor way. The rear sides of the Engesa turret, on which the most rearward smoke launcher was installed, went inwards instead of being a flat plate. It is unknown if this turret used bimetal armor or not. The vehicle was armed with a 90 mm gun and a coaxial 7.62 mm machine gun. In addition to its armament, the turret also mounted 2 pairs of 3 smoke grenade launchers on both sides of the rear turret.
It is unclear which company won this specific bid, as both the Engesa turret and the Bernardini turrets were never mass-produced. Interestingly however, in a platoon manual for mechanized units from 1977 (the first of its kind in Brazil), an EE-9 is presented with the Bernardini turret. The EE-9 was called: CBR MB-1 Cascavel. The MB-1 referred to the Bernardini turret and was armed with the French D-921 cannon.
What seems to have happened, was the switch from the D-921 gun to the license-produced EC-90 gun, which was based on the Cockerill 90 mm gun. Somewhere between 1975 and 1976, Engesa got a licensing deal with Cockerill for their 90 mm gun. This was an essential shift, as the forced purchase of both turret and gun from the French became increasingly expensive, and building a local turret would have been much cheaper. This turret design bid was most likely initiated around 1975 and probably ended when Engesa got the license deal in order. It is unclear if a new bid for an EC-90 armed turret was opened, but what is known is that Engesa would design the ET-90 turret which would be used on the Cascavels from that point on.
The EE-9 M2 37 mm
With the approval of the CRM by the Brazilian Army, 102 production vehicles were ordered. If these 102 vehicles were actually delivered is unclear. Pictures exist where at least 9 production vehicles, known as the EE-9 M2 Cascavel with 37 mm, are shown. According to statements from ex-Engesa employees, the order seems to have eventually been converted into an order for the 90 mm armed Cascavel M2 and the 37 mm EE-9 M2s were supposedly converted to 90 mm M2s. How many 37 mm M2’s were eventually built before the Brazilian Army switched the order is unknown. It is estimated that the Brazilian Army changed the order around 1977.
The production model differed from the CRM in a couple of ways. The most notable two were the copied and redesigned M3 Stuart turrets, which were now finally delivered, and the removal of the raised driver structure on the hull. Another very important change was the slanting of the rear hull. This was done to fix the issue of the turret bustle colliding with the engine bay covers, and enabled the usage of low-profile turrets. It is thought that the mounting of the 90 mm HS-90 turret initiated the redesign of the hull to accommodate the turret. Another change was the removal of the exhaust pipe on the right rear side of the hull. The exhaust was now mostly located inside the Cascavel, with the exhaust coming out of the right rear side of the vehicle, above the rear wheel. In essence, the EE-9 M2 was a streamlining of the CRM and mounted the final turret.
The EE-9 M2 37 mm was unofficially called ‘Cascavel Magro’, meaning Skinny Rattlesnake, while the 90 mm armed Cascavels were unofficially known as ‘Cascavel Gordo’, meaning Fat Rattlesnake.
The EE-9 M2 weighed 11 tonnes (12 US tons). It was about 5 meters (16.4 feet) long, 2.3 meters (7.5 feet) wide, and the height was around 2.3 meters (7.5 feet). The EE-9 had a three-man crew, consisting of the commander/loader (turret left), gunner (turret right), and the driver in the middle front hull.
EE-9 M2s at a parade, most likely an Independence Day parade around 1975. Source: https://webkits.hoop.la/topic/procurando-imagens-do-ee-9-cascavel-magro
Hull
The hull of the EE-9 M2 was manufactured from welded bimetal steel plates. The upper front plate was well angled at 60 degrees from vertical. The hull also features two covers which were mounted on the hull at the positions above the boomerang suspension, effectively functioning as mudguards and very minor spaced armor.
The front upper hull plate presented 16 mm (0.63 inch) of bimetal armor at an angle of 60 degrees. The sides and rear were 8.5 mm (0.33 inch) thick at varying angles, and the top and bottom hull were 6.5 mm (0.26 inch) thick. The front of the EE-9 was meant to protect from .50 machine gun fire at an unknown range, while the entire vehicle was protected from 7.62 mm AP rounds at 100 meters (109 yards), and standard 7.62 mm rounds at 50 meters (54 yards).
The EE-9 had two headlights externally mounted on top of both sides of the upper front hull plate. A rearview mirror could be mounted on both headlight guards. A black-out light was installed on the right side of the left headlight. Below the driver’s hatch was a foldable windshield, which the driver could use when driving with an open hatch. It is not completely clear in pictures, but it seems that the driver’s hatch was a two-piece hatch, with the front part being part of the upper front plate, while the back part was part of the top hull plate. The front hatch had three periscopes for the driver for 180 degrees of vision. These periscopes and other periscopes or sights would not have been active or passive night vision equipment unless the Cascavel was ordered with these devices.
A ventilation inlet was installed on both upper hull side plates, these ventilation inlets are recognizable by their frustum shape. A siren was installed behind the ventilation inlet on the right side of the vehicle. The fuel tank cap of the Cascavel was located on the left side, in the middle of the upper side hull plate. The EE-9 had a large ventilation grille on the rear of the vehicle, reminiscent of the M8, and had a rear light on both sides of the ventilation grill. The engine could be accessed through two large hatches on the hull top rear.
The driver steered the vehicle with a steering wheel and had his gear stick on his right side, and his instrument panel to his left. The acceleration pedal was located on the right side of the steering wheel, and the brake was next to the acceleration pedal on the left. On the left side of the steering wheel was the clutch pedal.
Mobility
The EE-9 M2 used the OM352 and the OM352A engines. These are both 6-cylinder inline diesel engines of which the OM352A is turbocharged. The OM352 produces 125 hp at 2,600 rpm and 353 Nm at 1,600 rpm, while the OM352A produces 172 hp at 2,800 rpm (DIN standard) and 431 Nm at 1,800 rpm. The Brazilian Army seems to have only used the OM352A engine, although it is unknown if the earliest Brazilian Cascavels might have received the standard OM352 engine to be rebuilt or replaced later on.
The M2 Cascavel had a top speed of 95 km/h (59 mph) and an operational range of 700 km (353 miles). It had a turning radius of 7.7 meters (8.1 yards) and it could ford a depth of 1 meter (3.3 feet). The Cascavel could climb a 35-degree slope, could climb a vertical obstacle of 0.65 meter (2.1 feet), cross a trench of 1.65 meters (5.4 feet), and had a ground clearance of about 0.5 meters (1.6 feet). The front-wheel could travel for 0.2 meters (0.66 feet), while the rear wheels could travel for 0.9 meters (3 feet). It used 11 X 20 run-flat tires with a diameter of 0.5 meters (1.6 feet). The EE-9 M2 had a distance between the front axle and rear axle of 2.8 meters, and a distance of 1.4 meter (4.6 feet) between the two rear wheels.
The EE-9 used a manual Clark 280V transmission with 5 gears forward and 1 in reverse. In addition, the Cascavel used an Engesa 2 speed transfer case, which allowed the Cascavel to be used in reduced and high gear. By putting the Cascavel in reduced gear, the Cascavel sacrificed horsepower for torque, making it more effective in climbing slopes. The vehicle was 6 x 6 driven, of which the rear 4 wheels were part of the boomerang suspension. The boomerang suspension, in combination with the Engesa 2 speed transfer case, enabled the Cascavel to cross challenging terrain and provide maximum traction in most situations. The power of the engine was distributed to a differential on the front side of the vehicle, and a differential in the rear. The rear differential drove the boomerang suspension with a single axle, which made the boomerang suspension such an ingenious design.
The Boomerang suspension used leaf springs for dampening. The two front wheels were used for steering. The wheels on the boomerang suspension all rotated at the same speed. The front wheels were dampened by large coil springs. The vehicle used hydraulic drum brakes, and was steered with hydraulics as well.
Transmission system of the EE-9 suspension. Source: Engesa manual
Turret
The turret of the EE-9 M2 was a copy of the M3 Stuart turret. The engineers lengthened the turret to fit radios in the new turret bustle. The turret had two hatches which opened in the same way as on the previous VBB-1 and CRR turrets. In front of those hatches was a machine gun mount. Both the driver and gunner had periscopes around their hatches. An antenna was located on the right rear of the turret. An openable hatch with a vision sight incorporated was installed on both sides of the turret. A basket for stowage was mounted around the entire turret bustle. The commander was located on the left and the gunner on the right.
The turret bustle of the EE-9 M2 with the radio mount on the left.
Source: Author
The armor of the turret is unknown. Considering it was a copy of the M3 turret, the protection levels might have been similar. An estimate of the EE-9 M2 turret protection would be that the front would have been armored with a plate of 51 mm (2 inch) thick at an angle of about 14 degrees from vertical. The gun shield would have been 38 mm thick (1.5 inch). The sides and rear of the M3 Stuart turret were 32 mm (1.26 inch) thick, and the top was 13 mm (0.5 inch) thick.
The EE-9 M2 turret Source: Author
Armament
The EE-9 M2 used a 37 mm M6 cannon as main armament. The 37 mm M6 had a total length of 2.1 meters (6.9 feet) and a bore length of 1.98 meters (6.5 feet). The 37 mm cannon was able to fire the M51 APC round with 53 mm (2.1 inch) of penetration at 455 meters (500 yards) at a 30-degree angle, and 46 mm (1.8 inch) of penetration at 915 meters (1,000 yards) at a 30-degree angle. It could also fire the M74 AP, M63 HE, and M2 canister rounds. In addition to the 37 mm cannon, the EE-9 mounted a coaxial 7.62 machine gun on the right side of the turret, and a .50 caliber M2 machine gun on top of the turret. Interestingly, some pictures show the .50 machine gun mounted on the front top of the turret, while others show the .50 machine gun mounted on the top rear.
The EE-9 M2 had access to 43 rounds of 37 mm ammunition, 400 rounds of .50 machine gun ammunition and 1400 round of .30 machine gun ammunition.
Fate
In the end, only 9 37 mm armed EE-9 M2s have been confirmed to have been built by Engesa. 102 were ordered, but it seems that the rapid developments on the export market of the EE-9 would quickly put an end to the M2 production order. By 1976, the order was probably converted to an EE-9 M290 mm order. The 37 mm EE-9 M2s were supposedly rearmed with 90 mm’s. How many 37 mm M2s were actually built and converted remains a mystery. If these 37 mm EE-9 M2’s ever were delivered to Army units and to which, is unknown. Some sources suggest that up to 50 M2s were built, but they are very vague about this number. It is at least certain that 9 were produced and were later converted to the M2 standard.
Although the 37 mm M2s did receive serial numbers, it is not known if they were operating in a unit or if they were still serving as parade vehicles. If the 37 mm EE-9 M2 was used in service, they would have served in the following mechanized platoon structure: 1 radio jeep, 4 reconnaissance jeeps, 2 EE-9 Cascavels, 1 Urutu, and 1 ammunition carrying jeep.
The EE-9 M2 of Brazil. Source: Private collection
Conclusion
The EE-9 M2 37 mm seems to have been more of a stopgap than anything else. Although the Brazilian Army wanted the 37 mm armed EE-9 M2, debates within the Army were already heading towards either an autocannon or a 90 mm cannon-armed Cascavel. It was at least quite clear from the start that the rest of the world wanted the 90 mm Cascavel. Considering the EE-9 M2 was already ordered by Libya, the M2 37 mm was already outdated before it was even put into production for the Brazilian Army. Eventually, the Brazilian Army folded towards the 90 mm, and made the decision definitive when Engesa could build their own turrets instead of importing them.
As such, the 37 mm EE-9 M2 itself was an excellent platform with an outdated turret. The Portuguese recognized the capabilities of the EE-9 and were the ones to give the nudge to Engesa to go forward and arm it with a 90 mm. The 37 mm was an armament of the past, while the boomerang suspension and the bimetal armor provided excellent mobility in combination with protection. The Brazilians had succeeded in building their improved version of the M8 Greyhound and established the groundwork for what became Brazil’s most-produced armored fighting vehicle of all time.
Illustrations
The VBR-2, done by Godzilla.CRR with the VBB-1 turret, done by Godzilla.The CRR with the M8 copy turret, done by Godzilla.How the CRR with HS-90 turret would have looked like, note the turret collisions. Done by Godzilla.The CRR/CRM hybrid with the 90 mm armed M8 inspired turret. Done by Godzilla.CRM with the modernised M8 inspired turret. Done by Godzilla.CRM with 37 mm armed BT-90 turret of Bernardini.The CRM with the 90 mm armed BT-90 inspired turret by Engesa. Done by Godzilla.The EE-9 M2 37 mm Cascavel, done by Godzilla.
Specifications EE-9 M2 37 mm
Dimensions (L-W-H)
5 meters x 2.3 meters x 2.3 meters (16.4 feet x 7.5 feet x 7.5 feet)
Front 16 mm (0.63 inch)
Side 8 mm (0.32 inch)
Rear 8 mm (0.32 inch)
Top 6.5 mm (0.26 inch)
Floor 6.5 mm (0.26 inch)
Turret
Front 51 mm (2 inch)
Gun mantlet 38 mm (1.5 inch)
Sides 32 mm (1.26 inch)
Rear 32 mm (1.26 inch)
Top 13 mm (0.5 inch)
Production
At Least 9, up to a hundred
Special thanks to Expedito Carlos Stephani Bastos, the leading expert in Brazilian vehicles, please visit his website for further reading on Brazilian vehicles: https://ecsbdefesa.com.br/, Jose Antonio Valls, an Ex-Engesa employee and expert in Engesa vehicles, Paulo Bastos, another leading expert of Brazilian Armored vehicles and the author of the book on Brazilian Stuarts and the website https://tecnodefesa.com.br, Adriano Santiago Garcia, a Captain in the Brazilian Army and ex-company commander on the Leopard 1 and ex-lecturer on the Brazilian Armored School, and Guilherme Travassus Silva, a Brazilian with whom I was able to endlessly discuss Brazilian Vehicles and who was always willing to listen to my near endless ability to talk about them.
Sources
Engesa EE-9 Cascavel 40 anos de combates 1977-2017 – Expedito Carlos Stephani Bastos
Ford M-8 Greyhound Exército Brasileiro – Surge o conceito de blindado 6×6 – Expedito Carlos Stephani Bastos
Blindados no Brasil – Expedito Carlos Stephani Bastos
Brazilian Stuart – M3, M3A1, X1, X1A2 and their Derivatives – Hélio Higuchi, Paulo Roberto
Bastos Jr., Reginaldo Bacchi
Engesa manuals
Engesa brochures http://www.lexicarbrasil.com.br/
Dual Harness skin stops armor-piercing projectiles Article of Richard M. Ogorkiewicz
Sipri Arms Transfer Database
Personal correspondence with Ex-Engesa Employees
Personal correspondence with Expedito Carlos Stephani Bastos
Personal correspondence with Paulo Roberto Bastos Jr.
Personal correspondence with Adriano Santiago Garcia
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Federative Republic of Brazil (1985)
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