Categories
Swedish armor

Stridsvagn 74

Sweden (1953-84)
Medium Tank – 225 Built

After the Second World War, Sweden was in urgent need of modern tanks. Their current medium tank, the strv m/42, was horribly outdated, being armed with a short-barreled 75 mm gun. The Swedish military was certainly impressed by French AMX-13’s and considered buying them, but eventually they concluded that their armor was too weak to fulfill their needs, along with several other flaws pointed out by General Swedlund. The deal with the French was cut-off and the Swedes eventually decided to buy the British Centurion, which offered significantly better protection against nuclear weapons and conventional weapons.

However, the need for a light tank still persisted. Designing a completely new tank would take too long, around seven years, so instead the Swedes chose to reuse the chassis of the wartime strv m/42.

The idea of upgunning the strv m/42 had been proposed earlier, in 1944. The design would feature a new turret complete with a new gun and autoloader. The turret was named “delat torn”, meaning “split turret”, because the autoloading mechanism would split the turret into two separate compartments. The gun was placed far back in the turret in order to reduce the barrel overhang. A mockup of the turret was made and tested in 1944 and was later prototyped in 1945, but tests in 1946 proved that the design was flawed.

The turret that was designed for the upgraded Strv m/42 in 1944. Source

The idea to overhaul the strv m/42 to improve its performance was brought up again in 1953. To revive this old chassis, a new turret was needed in order to fit a more capable gun. Firstly, it was considered to put the turret of the recently studied AMX-13 onto the chassis, but this was not deemed possible as the turret ring was too small. Therefore, a completely new turret was designed. The gun of choice was the 7,5 cm lvkan m/36, one of the most effective Swedish heavy anti-aircraft guns. Modified as a tank gun, it was capable of penetrating 260 mm armor at an angle of 90 degrees at point-blank.

The lvkan m/36 in its original configuration. Note the big, single recoil chamber that would later be replaced when converted to a tank gun. Source
Armor scheme for the strv 74. Source

In early 1954, two prototypes were ordered by the Swedish military. One of the main reasons this project was ambitiously supported by the military was the fact that the new turret modification was cheaper than buying a foreign tank. Because the old strv m/42 turrets would later be used as fortification turrets, the new turret could not reuse any of the old parts. As the strv m/42 EH was only available in small numbers and suffered reliability issues because of its Volvo engine, the double-engined strv m/42 TH and TV variants were chosen to mount the new turret on.

Prototype strv 74 during exercises. Note the muzzle brake. Source
The Bofors gun in the factory, receiving its new recoil system. Source

Turret

The new turret had a futuristic look, being heavily sloped on all sides. Crew conditions were certainly improved over the Strv m/42, with the roomier turret making operating the tank a lot more comfortable. In order to keep production simple, many of the Centurion’s components were used, such as the turret traverse override, the sights, smoke dischargers, sextant and many more. The back of the turret was occupied by an industrial Volkswagen engine, providing power through an electric generator for ventilation and heating. The unique design of the turret, with a specialized gun mantlet, enabled the gun to depress up to an impressive -15 degrees. However, the armor protection was quite disappointing, only 20 mm at best. The armor was kept modest in order not to add any additional stress on the already heavily overloaded suspension.

Armament

The original recoil system for the gun had to be replaced, as it was far too big to be mounted in a turret. Besides replacing the old recoil system with a new one, the barrel was slightly cut down as well. A new balancing component for the gun, invented by engineer Sven Berge, who would design the strv 103 later in his career, was also tested and proved to be satisfactory. New APDS (Armor Piercing Discarding Sabot) ammunition further improved the anti-armor capabilities of the gun. The hull machine gun placed on the right side of the driver was removed in order to create more room for the ammunition, as the new shells were much longer than the shorter shells the strv m/42 used. An 8 mm ksp m/39B strv machine gun was stationed on top of the turret and another one was placed coaxially.

Strv 74 prototype in hull-down position, showing off its formidable gun depression. Source

Chassis and Body-on-Frame

The heavier turret meant that the chassis had to be revised. The expected weight increase was calculated at 1.5 tonnes, an estimation far from reality. In fact, the increase turned out to be more than double the planned weight increase, 3.5 tonnes. As a result, the front was reinforced, the shock absorbers were replaced with improved ones and the steering mechanism was changed. The tracks were slightly widened, making the ground pressure 25% less, a much needed improvement. Changes to the driver’s hatch were also made. The hatch received a double prism periscope, but the driver did have a harder time getting in and out of the tank. This was because the turret traverse blocked the hatch and prevented it from fully opening up. Plates were put (Note: not welded, they were apparently attached to hinges) over the steering gear hatches in order to make the vehicle NBC proof.

Engine and Other Driving Mechanics

The engines were replaced by the more powerful Scania-Vabis 607 engines, which themselves were improved as well by replacing the carburetor with direct injection. They now delivered 340 hp as opposed to the 325 hp on the original strv m/42. This also resulted in much lower fuel consumption and allowed the engines to function properly at temperatures as low as -25º C.

Radio Equipment

The radio equipment consisted of 3 independent radios: one for internal communication, one for communication within the battalion and one to communicate with the infantry. Just like most German wartime vehicles, a laryngophone (throat microphone) was used for local communication.

Trials

Tests at Särna proved to be successful and more modifications were added to the turret, such as a spare road wheel, smoke dischargers and a turret basket. The idea of attaching a fuel trailer to the tank was abandoned after it was made possible to hang 10 jerry cans at the back of the vehicle, as it was much more practical. This would give it a wider range during mobilisation, but it was eventually decided not to add the jerry cans at all.

Tests were conducted with three different caliber weapons in order to measure the effectiveness of the turret armor:

Firstly, a 20 mm “tubkanon” (a smaller caliber gun inserted into a larger caliber one, usually used during practice in order to reduce costs) was fired, using 20 mm slppjr m/42 rounds. It proved unable to penetrate the turret front, however, the sides were consistently penetrated from a distance of less than 300 m.

Secondly, a Bofors 37 mm pvkan m/34 anti-tank gun was fired, using 37 mm slppjr m/49 rounds. It was able to penetrate the armor at all sides at a distance of less than 750 m.

Lastly, the 75 mm gun of another strv 74 was fired, using 75 mm slppjr m/49 rounds. It was able to penetrate the turret mantlet from a distance of 1,400 m and cause significant damage to the interior. Its effective distance could quite possibly be more, but this was not tested.

Production

After the design was completed, the production of the two prototypes could begin. The first prototype had a wooden mockup turret, roughly presenting how the strv 74 would look like. The same ammunition as on the pvkv m/43 was used, which made production even cheaper.

After satisfactory tests, manufacturing the production series of strv 74 began in 1957. 225 vehicles were ordered, and the orders were equally spread among the companies Hägglunds & Söner and Landsverk which produced military equipment. Two variants of the strv 74 were produced: the H-variant and the V-variant. The H-variant was based on the strv m/42 TH and the V-variant on the strv m/42 TV. The differences between these versions being only minimal. The gearboxes differed from each other, one being mechanical and the other hydraulic. The order was fully completed in 1960.

Active service

The strv 74, just like all other Swedish Cold War tanks, never saw combat. They were dispersed among 4 armored brigades, each receiving 48 tanks. The crew consisted of 4: a commander, a gunner, a loader and a driver. Even though the strv 74 was originally designed as a light tank, the military decided to turn them into infantry support vehicles in the 1960s. Their numbers started to decline when the new ikv 91 entered service, as it was much more efficient in its role of infantry support. The new 90 mm gun it was equipped with provided significantly better anti-armor capabilities than the 7,5 cm kan strv 74. The remaining strv 74s were either stored and kept as reserves or dedicated to other secondary roles. The very last of the strv 74 was retired in 1984. Some of the turrets were recycled and placed on bunkers along the coastline (the so-called ‘värntorn’), staying there up until the late-90s
.

Conclusion and Fate

The Swedish military considered the project to be a success. Had they bought the French AMX-13 instead, their expenses would have been SEK 80 million (roughly 8.5 million USD) higher, quite a considerable amount. Opinions on the tank however still remain mixed. The profile of the vehicle was quite high and the torsion bars were heavily stressed under the turret’s weight. Many crew members had positive reflections about the vehicles, maintaining that as soon as you ‘had come to know their personality’, they would function properly.

A few Strv 74s have survived to this day and are currently stored or on display at the Arsenalen Museum, the Föringen P5 Museum, Försvarsmuseum Boden, the Kubinka tank museum, the Hässleholms Museum, the Gotlands Försvarsmuseum, the Saumur Museum and the American Armored Foundation Museum. Some were also used as targets on firing ranges.

Strv 74 at Försvarsmuseum Boden. Source: Andreas Lakso on Wikimedia Commons
Strv 74 at the Kubinka Tank Museum. Source
Strv 74 at the Hässleholm Military Vehicle Museum. Source


Illustration of the Stridsvagn (strv) 74, produced by Tank Encyclopedia’s own David Bocquelet.

strv 74 specifications

Dimensions 7.9 (6.1 o.a.) x 2.4 x 3.3 m
Total weight 26 tonnes
Crew 4 (Commander, Driver, Gunner, Loader)
Propulsion (TE and TM) 2x Scania-Vabis type 607, each 170 hp
Gearbox H-variant: Hydraulic gearbox
V-variant: Mechanical gearbox
Speed (road) 45 km/h
Armament 7.5 cm kan strv 74
2x 8 mm ksp m/39B strv
Armor 8-55 mm
Total production 225

Sources

www.ointres.se
www.ointres.se/sven_berge.htm
ftr.wot-news.com
tanks.mod16.org
tanks.mod16.org
the.shadock.free.fr


Categories
Swedish armor

CV9040A and B

Sweden (1991)
Infantry Fighting Vehicle – 345 built

Early in the development of the CV90, it was decided that the CV 9040 version should be developed into a family of vehicles comprising four additional variants:

  • CV90 FCV (Forward Command Vehicle)
  • CV90 FOV (Forward Observer Vehicle)
  • CV9040 AAV (Anti-Aircraft Vehicle)
  • CV90 ARV (Armored Recovery Vehicle)
Strf 9040A. Photo: Måns Thuresson

The basic design philosophy of the CV9040 emerged from the few overarching requirements given by the Swedish Defence Materiel Administration (Försvarets materielverk, FMV) in a priority list, with mobility in northern Sweden being at the top. This emphasized the necessity to reduce the vehicle’s weight without negatively affecting the armament and protection. As the armored hull took up most of the weight, the philosophy was to make the vehicle “big on the inside and small on the outside” or, otherwise said, the vehicle layout had to be as volume efficient as possible.

Any increase in weight and volume lead to a negative feedback spiral, as a heavier or larger vehicle requires the upsizing of many subsystems, which in turn lead to more weight and more occupied volume. During the development of the CV90, the designers realized that every useful feature that could be added to the design or its subsystems had a price to be paid in terms of useful volume and weight.

Terramechanic simulations undertaken during the development stage led to the conclusion that the track ground contact length should be as long as possible in order to ensure a low ground pressure and high mobility even on soft terrain. At the same time, the number of road wheels should be as large as possible and they should be arranged close together in order to create an even distribution of the vehicle’s weight.

CV 90 track assembly layout. Source: Hägglunds)

In order to have good steering performance, the ratio between the track ground contact to the distance between centerlines of the two track center lines should not exceed 1.7. This put an upper limit on the vehicle length, as the width was already limited by external limitations for road and rail transport.

In order to ensure that the vehicle would not get stuck on obstacles, the armored hull should not protrude too much in front or behind of the track assembly. These mobility concerns more or less determined the maximum possible length of the armored hull and, thus, the maximum size of the role-specific volume. The role-specific volume is the internal vehicle volume left after subtracting the volume needed for the armor, suspension and automotive components.

Chassis Layout

The CV 9040 has a three-man crew consisting of a driver, a commander, and a gunner, with the commander and gunner operating the turret. In the rear of the vehicle, a rifle squad with eight fully equipped soldiers is carried, who can disembark through the rear doors. This was later reduced to seven men in order to free up space for more equipment.

CV 9040 main layout. Source: Hägglunds)

It was preferred to have the load area rectangular in shape and as long as possible. It was also decided that no other vehicle systems, such as the transmission or fuel tanks, should intrude in the role-specific area in order to provide a common base within the vehicle family. The length of the role-specific volume was increased by the use of a short power-pack. For this, the natural engine choice was the Swedish Scania DSI14 V8 diesel giving 550 hp.

By placing the cooling system in the rear of the right-side sponson, the driver´s station and the engine compartment could be efficiently placed side by side at the front of the vehicle, without any other ergonomic compromises. The CV 9040 turret has a shallow basket offset to the left side and above the bottom of the track sponson.

CV 9040 driver´s station and engine compartment: Left photo: Saddam the explorer, engine compartment photo from Mats Carlsson, Försvarsmakten
Ammunition stowage and escape hatch under the turret. Photo: Hägglunds

The dimensions and volume needed for the rifle squad were determined during early mock-up tests made by the Swedish Army. In comparison with the American M113 APC, the troop area in the CV9040 is taller and approximately 200 mm wider.

The space needed for a sitting soldier is directly linked to the vehicle’s internal volume and the sitting position is also closely related to the vehicle’s width and height. In the CV 9040, the soldiers’ seats have a “relaxed” position that lowers the required height of the compartment and of the vehicle. Mine tests with instrumented test dummies have shown that the seats gave good and well-distributed support for the backbone which reduced the risk of severe injury from explosion shocks from underneath.

The conventional seating position (left) would mean an increased roof height to cover the soldiers sat in the back, but the semi-reclined position (right) reduces the height of the vehicle. The popular ‘babysitter’ seat was the inspiration for the seat design in the CV 9040. One of the requirements was that it should be comfortable to sleep in, something soldiers know is important.
Soldiers sleeping inside a CV9040. Photo: Bezav Mahmod, Försvarsmakten

Early full-scale complete-vehicle mock-ups showed that an inclined hull rear wall was optimal for exiting the vehicle. This also gave a shortened the hull bottom, and it eliminated any issues related to the lower hull protruding beyond the track assembly.

The roof above the rifle squad has a 1° inclination with the purpose of increasing the height of the rear door. Two large, rectangular hatches are located on the roof, allowing for close fire support from two soldiers on each side.

Four soldiers inside a CV 9040 popping their heads out of the roof hatches to provide fire support; There is a support for 7.62 mm machine-guns on each side of the troop compartment, with the other two soldiers using their personal weapons. Photo: Henrik Svensk

Size of the CV 90 Compared With Other IFVs

The low frontal height of the CV 9040 was made possible by having the radiators in the rear part of the right sponson instead of above the engine. Due to this placement of the radiators, all of the major systems in the vehicle’s front are at the same height, an important factor for high volume efficiency.

The CV 9040’s cooling system air outlet at its rear; Photo Niklas Englund, Försvarsmakten
By having a focus on weight and volume, the CV 90 is approximately three tonnes lighter than other vehicles in a comparable role.
Size comparison between the American M2 Bradley and the CV9040. Source: Raino Sommer

Power-Pack

The CV90’s 550 hp power-pack consists of a Scania DSI14 engine built together with the X-300-5 transmission originally developed by Detroit Diesel Allison for the M2 Bradley.

The basic Scania truck engine was modified for a dry sump lubrication system to reduce the engine height and allow for operation at large vehicle inclinations.

The X-300 transmission was first used in the British Warrior IFV under the X-300-4B designation. It is a fully automatic cross-drive transmission offering four forward and two reverse gears driven through a torque converter with a lock-up clutch.

Steering is continuously variable (meaning the vehicle can turn with any turning radius) with true pivot turn in neutral (meaning it can turn on the spot) which is achieved with hydrostatically controlled double differentials. Service and parking brakes are incorporated into the transmission and they are hydraulically applied with mechanical back-up.

The Swedish version has the designation X-300-5. The main difference is that the transmission oil filter is inclined to enable a direct assembly to the engine.

Power-pack with crankshaft coupling for hydraulic pump drive. Photo: Hägglunds

During cold chamber tests, excessive oil pressure occurred, leading to transmission damage, a significant problem for a Swedish IFV given the harsh winter climate. Modifications to the transmission were introduced to limit pressure build-up. The cold start problems were solved by these modifications together with the use of synthetic oil with better low-temperature viscosity.

Cold chamber tests in Karlsborg. Photo: Försvarsmakten

The power-pack is designed with a minimized number of connections in order to enable a fast exchange of the complete unit without drainage of fluids. The hydraulic system’s reliability is closely linked to oil cleanliness and it is therefore important to avoid opening the system at a power-pack lift.

The complete hydraulic system is located in the chassis, there is no power-pack hydraulics. The pump unit is located in the rear part of the engine compartment and the pumps are mechanically driven from the engine crankshaft. A disconnect of the drive shaft is the only action at power-pack lift.

Power-pack lift; Photo Mats Carlsson. Photo: Försvarsmakten

Maintenance and repair are also possible without a power-pack lift as most subunits are accessible from inspection hatches in the engine compartment walls.

CV 90 Suspension and Tracks

As with the CV90 in general, the suspension was designed with efficiency in mind. Besides being weight-efficient, the suspension also has a low height in order to allow as much volume as possible inside the hull sponsons.

The Infanterikanonvagn 91 was the first armored vehicle in the Swedish Army that met the mobility requirements for use in northern Sweden due to low ground pressure in addition to a favorable suspension and track design from a mobility standpoint. This vehicle was the natural starting point for the design of the CV90 track and suspension system.

The Ikv 91 had six road wheels. Each was 670 mm in diameter and had 220 mm of travel. The bottom of the sponsons acted as a stopper for the road wheels, preventing the torsion bars from being overloaded. The large road wheel diameter, in combination with the limited road wheel travel, made it possible to use conventional linear shock absorbers.

The Ikv 91. Seen here a Tankfest 2018. Photo: Mark Nash

The road wheel diameter of the CV90 is smaller than that of the Ikv 91 in order to enable the installation of seven wheels in a densely packed configuration. The M2 Bradley’s tracks and 610 mm road wheels were a natural choice to use, with the additional benefit of ease of production. The increased road wheel travel in the CV90, together with these smaller wheels, means that there is no room for conventional linear dampers.

CV9040 track assembly. Photo: Daniel Klintholm, Försvarsmakten

The CV90 rotary dampers exist in two versions, the first one is designed to cope with the high gun recoil at salvo firings, being lockable. The introduction of a stabilized turret in the CV9040B upgrade opened the possibility of introducing a new damper which did not have to support locking in place for firing.

CV9040 Turret

The 40 mm gun in the CV9040 is based on a modified 40 mm L/70 towed anti-aircraft gun, but inverted with the ammunition feed from below. The gun can fire single shots or salvos of 4 or 8 rounds, with an automatic rate of fire of 5 rounds/sec. The spent cartridge cases are ejected upwards and forwards through a hatch in the turret roof.

CV9040 firing, note the ejected cartridge case. Photo: Daniel Klintholm, Försvarsmakten

Additional armament consists of a 7.62 machine gun and two banks of Galix smoke dischargers that fire IR concealing smoke grenades. The 7.62 mm coaxial machine gun is linked to the 40 mm gun and aimed from the main gun’s UTAAS sight. The turret can be rotated 360 degrees and has an electric gun drive system with a manual back-up in both elevation and traverse. The turret houses two crewmembers, the commander and the gunner, sitting on either side of the Bofors 40 mm L/70B gun system.

CV9040B turret with a standing commander. Note the closed sight cowl. Photo: SPHF

The commander has seven fixed periscopes for all-around visibility. The hatch can be locked in an “umbrella” position enabling the commander to have direct observation with overhead protection.

The commander of a CV9040 observing his surroundings with the hatch in the ‘umbrella’ position. Note the smoke dischargers and the open empty case ejection hatch. Photo: SPHF

The gunner has the UTAAS IR-sight in front. The top module of the sight has an armor protection cowl that can be opened from inside the turret. The gunner is provided with three periscopes for observation to the right of the turret.

The right side of the turret with the gunner’s observation periscopes. Photo: SPHF

CV9040 Ammunition

The ammunition magazines are divided into three eight-round compartments. Each compartment is loaded with one type of ammunition. The change from one compartment to another is done by sliding the magazine sideways. With those three compartments, different ammunition combinations can be fired in the same salvo.

The 40 mm L/70 gun system. Source: Bofors

One basic requirement was that all types of existing L70 ammunition should be usable by the CV90’s gun. In addition to the existing types of High Explosive (HE) ammunition, a new Armor Piercing Fin Stabilized Discarding Sabot (APFSDS) ammunition was developed.

Newly developed 40 mm ammunition for the CV 9040. Source: Bofors

In order to further enhance ammunition performance, the new programmable 3P ammunition was introduced (3P ammunition – Prefragmented Programmable Proximity fuzed ammunition). A video of the 3P ammunition in use can be found HERE.

The 3P bursting munition has a programmable multi-function fuze that can be set in one of six modes in order to achieve the best effect on target. Each 3P fuze is automatically and individually programmed by a Proximity Fuze Programmer which continuously receives data from the Fire Control Computer. Immediately before firing, the fuze is programmed to the selected mode.

Reloading the gun is done by a rotatable carousel that is easily accessible by both the gunner and the commander. This carousel can store 48 rounds and is a part of the turret basket.

Strf 9040A turret with ammunition carousel. Photo: Lovisaulrika – improveme.se

UTAAS Sight and Fire Control System

The basic requirements for the fire control system come from the seven-point priority list. Namely, it has to be effective against land targets and, at the same time, be effective against low flying aircraft and helicopters.

CV9040 gun at full elevation: Photo: David Gernes, Försvarsmakten

UTAAS is short for Universal Tank and Anti-Aircraft Sight and it is designed to be effective against both ground and air targets. The design of the top module allows for large lead angles in both azimuth and elevation that are essential for effectiveness against fast aircraft.

CV9040 UTAAS sight. Photo: SAAB

The sight is of a modular design with an integrated fire control system that includes both a ballistic calculator and a variable repetition frequency laser rangefinder for both ground and air target capability.

UTAAS has an independent line of sight that enables the operator to retain the target in the center of the reticule during the entire aiming and laser range-finding sequence. No re‑aiming is needed. Gun-laying is automatically controlled by the fire-control computer.

Night and all-weather operations are enabled by a thermal camera integrated to the sight. A monitor at the commander’s station gives access to the IR picture from UTAAS.

CV9040 Variants in the Swedish Army

The first 9040 serial vehicles were delivered in 1994, with the last deliveries being completed in 2002. Originally, these vehicles did not have a fire on the move capability due to the lack of a gun stabilization system.

The later produced CV9040A version can easily be recognized by the addition of a damping cylinder on the turret front that reduced gun oscillations during movement.

CV9040 first turret version on the left, CV9040A turret on the right. Photo: SPHF

A number of modifications were introduced during production, primarily to improve firepower and to allow for firing on the move. All the first series of Strf 9040’s were later rebuilt to the same standard, named CV9040A. In addition to turret modifications, more storage and better emergency exits reduced the number of seats in the troop compartment to seven.

In total, 209 Strf 9040A have been produced or converted. Of these, one vehicle was rebuilt to an electronic warfare vehicle. All the remaining Strf 9040A vehicles are still in service with the Swedish Army as of the writing of this article.

The 146 remaining CV9040 were all produced to the CV9040B standard. The Strf 9040B turret has an improved stabilization system for firing and observation on the move and the external damping cylinder was removed.

Important inputs for the suspension redesign of the Strf 9040B variant came from the Norwegian testing of the CV9030, where early tests of firing on the move clearly showed the necessity for an improved suspension system. These tests included firing at different vehicle speeds on an obstacle track representing extreme rough terrain. During these trials, it was recognized that the performance of the suspension system was an essential part of achieving a good hit accuracy.

With the fully stabilized 9040B turret, the suspension dampers could be redesigned to only account for mobility aspects. Above the dampers, a new set of torsion bars was introduced having lower spring resistance, leading to better crew comfort and improved hit probability at high vehicle speeds.

CV9040B turret with back-up sight to the left side of the gun. Photo: SPHF

146 CV9040Bs were produced and 55 vehicles of those are upgraded primarily for peacekeeping missions. The Strf9040B1 and Strf9040C versions are upgrades to already produced CV9040B´s.

  • Strf 9040B1: 13 Strf 9040B vehicles were modified for international peacekeeping missions, having a 3P ammunition programmer, climate control and anti-spall liner.
  • Strf 9040C: 42 vehicles were upgraded for international peacekeeping operations. This version has add-on armor, laser filtering in all periscopes and tropical grade air conditioning. Due to the bulk and weight of the upgrade, only six soldiers are carried.

The Strf 9040 were deployed with combat units spread all over Sweden for home defence and training. The Swedish Strf 9040, 9040A, and 9040B did not see any combat action. Only the Strf 9040C version saw action in Liberia and in Afghanistan. The CV90 platform also saw action with other countries, but the Strf 9040, A and B were not tested in actual operations.

Conclusion

The Strf9040 was a success for the Swedish army, which not only acquired hundreds of vehicles for its own use, but is also planning to upgrade them in order to keep them in service for the foreseeable future. The Swedish army also uses other variants of the CV90 chassis for other roles.

The Strf9040 did undergo a series of improvements during production and upgrades after its entry into service, mainly dealing with gun stabilization and mobility aspects.

The true claim to fame of the Strf 9040, however, is the fact that the CV90 platform has been a worldwide commercial success, with six other European nations operating hundreds of CV90 vehicles. The CV90 is also proposed to several other countries looking to replace their obsolete IFV fleets.

At this point, the CV90 is the most common Infantry Fighting Vehicle used by the nations of the European Union and will probably play an important role if a common EU army ever comes to fruition.



A Swedish Strf 9040A in a usual Swedish three-tone camouflage scheme. Illustrated by Tank Encyclopedia’s own David Bocquelet.

Strf 9040A

Dimensions LxWxH 6.55 x 3.17 x 2.77 m
Weight 23.5 tonnes
Crew 3 (driver, gunner, commander) + 7 passengers
Powerpack Scania DSI14 8-cylinder Diesel engine giving 550 hp (404 kW) with a Perkins automatic 4+2 gearbox
Suspension Torsion bars
Maximum speed 70 km/h
Maximum range 320 km
Armament Bofors 40 mm L/70 autocannon
7,62 mm ksp m/58C machine-gun
Galix grenade launchers
Total built 345 built

Sources

Video presentation of CV9040 prototype
FMV presentation of the CV90 project
Swedish Armour Historical Society SPHF: CV 90 Photo guide, 2010
Sources for further information in Swedish
Svantesson, C.-G. & Lindström, R.O.: Svenskt Pansar – 90 år av svensk
stridsfordonsutveckling, 2009
Presentation of the CV90 project by Rickard O. Lindström
Swedish Armour Historical Society SPHF

About the Author

Alfons Falk graduated in 1967 from the Royal Institute of Technology (KTH Stockholm), majoring in aircraft engineering. In 1975, he started his employment at BAE Systems Hägglunds and became the head of armor vehicle design in 1979, later to include test and verification. Being the head of all armored vehicle design, he has been responsible for the development of the CV90 for Sweden and thereafter for CV90 export versions.

In 2005, The Society for Swedish Mechanical Engineers (SMR) presented him with the Ljungström Medal, an award given only once every three years. The medal was given with the following commendation:

“CV90 – today the most modern IFV in the world – has been a great success in Sweden and internationally. Alfons Falk’s wide knowledge, commitment and ability to transfer operational requirements to excellent technical solutions from system level to detailed design have been decisive for the success of all BAE Systems terrain vehicles. His systematic way of working has changed the development culture within the company.”


Categories
Swedish armor

Pansarbandvagn 302

Sweden (1961)
Armored Personnel Carrier – 350 built

The second Swedish APC

The PBV 301 was the first tracked armored personnel carrier developed for the Swedish army, but it was based on already existing chassis of the old Stridsvagn m/41, itself a licensed copy of the Czechoslovakian Škoda TNH of the thirties. The running gear of the Panzer 38(t) and ‘Hetzer’ can immediately be recognized on the PBV 301. However the PBV 302 (PBV stands for Pansarbandvagn, which translates to armoured tracked vehicle) was a completely new design, from scratch.

PBV 302 at Revinge, 2013
For a larger and more mobile vehicle, the easiest solution would have been to buy the US-built M113 which was just entering service. However, for reasons of neutrality, sovereignty and technological independence, the Swedish authorities preferred a local solution. This led to the PBV 302 in 1961, alongside with the conversion process for the PBV 301 which took place between 1962 and 1963, underlining its stop-gap nature. Both vehicles were quite different.

Development

The general design of the PBV 302 was fairly simple. Hägglund & Söner (the same that manufacture today the famous CV90) started work on the vehicle in 1961, and the preliminary design was ready in 1962, just one year after the project was launched. This first prototype was tested, followed by others, with modifications requested throughout the trials. This culminated in 1966 with the acceptance of the vehicle into service with the Swedish army. Production started the same year and ended in 1971 after 650 had left the factory doors. They replaced the PBV 301 completely, and no PBV 302 was ever exported.

Design

The PBV 302 strongly resembles the contemporary M113 in its shape and capabilities. They were, in the end, designed in the same period. However, the Swedish vehicle had a far more rounded hull and a 20 mm (0.79 in) Hispano-Suiza auto-cannon, just like the PBV 301, which was far more effective than the American cal.50 (12.7 mm). Another difference is that the PBV 302’s hull was made of welded steel. Compared also to the PBV 301, road wheels were quite different to the Str m/41 basis as there are now five, smaller, and with no gap between road wheel 2 and 3. The chassis also has been lengthened from 5.35 m compared to 4.54 m. However, they share a similar type of suspensions.
Its total weight was around 13.5 – 14 tonnes, the same as that of the M113, but the US vehicle was protected by an aluminum-magnesium alloy with 38mm of this alloy frontally compared to 23mm of steel armor on the PBV 302. Their capacities were similar, with a crew of three and eight soldiers in the back. Their top speeds were also similar, around (67 and 66 km/h), due to their similar powered engines (270 and 275 hp). The PBV 302 was of course amphibious.

Prototype, Sextant blog
The particular configuration of the vehicle was due to its rounded hull, both at the front and at the back, contrary to the more angular M113. The driver was seated in the front of the vehicle in the middle, with the engine to his back. The commander and the gunner were to either side of the driver, the first in a rotating cupola to the right and the second in the turret on the left.
Lacking any side viewports or portholes, the infantrymen, who were seated at the back of the vehicle on two benches placed back to back, could instead stand up and fire through two foldable roof panels. This may be the reason why Nuclear-Bacteorological-Chemical (NBC) protection is not mentioned as an option in the documentation. The infantrymen could access the vehicle through the two rear doors.

Protection

As already mentioned, the PBV 302 was protected by welded steel armor with a thickness of 23 mm on the frontal arc. The effective thickness is enlarged due to the angle of the front plate and the curvature. The rest of the vehicle was protected against small caliber weapons and shell shrapnel. The cast conical turret was the same as on the Swiss M113 or Gabon’s EE-11 Urutu vehicles. The active protection evolved afterward and the PBV 302 received, as standard, six smoke-grenade launchers and two Lyran flare launchers on the roof.

Armament

With the adoption of a Hispano-Suiza de 20 mm automatkanon m/47D type 804 autocannon, the PBV 302 was far better armed than the regular M113. The cannons were available after the SAAB 29 airplanes were retired and disarmed. However, the PBV 302 was not a true Infantry Fighting Vehicle. The cannon could be elevated from -10° to +60° and rotate a full 360°. It could fire high explosive shells in bands of 135 or armor piercing rounds in short magazines of 10 shots.

PBV 302 at Revinge, 2014
This complex system was replaced by the use of ten universal magazines with 30 shots each, giving 300 shots in total (505 according to another source). The cannon had a foldable sight theoretically used for ranges up to 2000 m and precision anti-aircraft fire. The turret was also armed with a coaxial Ksp 58 7.62 mm (0.3 in) machine-gun with 1000 rounds carried.

Mobility

The heart of the vehicle sat between the crew members. The engine compartment held a Volvo THD 100 diesel capable of developing 270 hp (201 kW). This gave a 19.3 hp/tonne power-to-weight ratio. In turn, this allowed the vehicle to reach 66 km/h (41 mph) on road, with a range of 300 km (186 miles). The suspension used the same components as the Infanterikanonvagn 91 light tank, including the drive wheels at the front, idlers at the rear and 5 rubberized road wheels connected to torsion bars.
The vehicle was amphibious but required some small preparations by the crew beforehand. In water, the vehicle was propelled and maneuvered by its tracks. Its light construction was well adapted to the conditions of the Swedish countryside, wet and muddy in the summer, snowy in the winter. The vehicle had a small ground pressure and a favorable power-to-weight ratio.

Evolution & variants

Despite the small number built, the PBV 302 and its chassis were used for a large number of specialized vehicles

Evolution

PBV 302A: Basic version
PBV 302B: Improved version with interior spall liner and added armor
PBV 302C: Modernized version with the preceding modifications and a reinforced suspension, new headlights, flare launchers, a new turbocompressor and air conditioning. This version was used briefly in Bosnia and Kosovo before it was withdrawn.

Radiolänkpansarbandvagn 3024

Variants

Stridsledningspansarbandvagn 3021: Batallion and brigade-level command vehicle.
Eldledningspansarbandvagn 3022: Advanced artillery observation vehicle.
Batteriplatspansarbandvagn 3023: Artillery command and control vehicle.
Radiolänkpansarbandvagn 3024: Radio communication vehicle.
Pjäsrekognoseringspansarbandvagn 3025: Artillery reconnaissance vehicle.
Sjuktransportpansarbandvagn 3026: Armored unarmed ambulance.
Bärgningsbandvagn 82: Repair and support vehicle based on the PBV 302.
Brobandvagn 941: Bridgelaying vehicle based on the PBV 302.

Service

The PBV 302 was produced by Hagglund & Soner and entered service in 1966. With 350 built, without counting the variants, it was the main armored tracked personnel carrier of the Swedish army for many decades before its retirement in the 2000s. In fact, the first batch of 160 vehicles was retired in 2005, followed by a partial retirement of 210 others (C versions) in 2007.  By 2009 the total retirement was planned, but it was decided that the C versions would remain active until 2018. A project was made to prolong the operational life of the vehicles by 20 years but, given the estimated cost, the proposal was turned down by the army.

PBV 302 IFOR, Bosnia
None were ever exported, as the rules on the matter are very strict in this regard. For this reason, the vehicle is little known outside the realm of the three crowns. The PBV 302 was replaced by the more powerful CV-90 infantry combat vehicles, the BV 308 for winter operations in the north and Finnish Patria wheeled vehicles.


Basic Green BVP-302 in the early 1960s

Standard four-tone Swedish camouflage of the 1980s.

Gallery




Video: PBV 302 live

Links/sources

The PBV on Army-Recognition
Additional data and photos
The Pansarbandvagn 302 on Wikipedia (photos)
Additional photos from the Pansarmuseet
https://www.soldf.com/pbv302.html
https://www.mvif.se/pdf/publ/7782012322.pdf
https://www.revolvy.com/main/index.php?s=Pbv%20302&item_type=topic

Pansarbandvagn 302 specifications

Dimensions (L-w-h) 5.35 x 2.86 x 2.5 m (17’7”x9’5”x8’2”)
Total weight, battle ready 14 t (28,000 lbs)
Crew 3+8 (commander, gunner, driver, 8 infantry)
Propulsion Volvo THD 100, 270 hp (201 kW), 19.29 hp/t
Top speed 66 km/h (41 mph)
Range 300 km (186 mi)
Armament Hispano mk.V 20 mm automatkanon m/47D (0.8 in)
Suspensions Torsion bars
Armor From 8 to 23mm (0.3-0.9 in)
Production 350
Categories
Swedish armor

Stridsvagn 104

Sweden Sweden (1953)
MBT – 212 built

The Swedish Centurion

In the early 1950s, the British Centurion was a big hit, already proven in Korea and precursor of the main battle tank new generation of “universal tanks”. However, if the Swedes approached the British Government but the latter then declined any exports, as it estimated that the needs of the British army had been satisfied first, which was deemed to take between five and fifteen years. Meantime, medium tank developments were led by the vehicle bureau of KAFT with the EMIL programme.
bargningsbandvagn_81_revinge_2012
Bärgningsbandvagn-81 ARV at Revinge in 2012.

Hello dear reader! This article is in need of some care and attention and may contain errors or inaccuracies. If you spot anything out of place, please let us know!

This was dropped later and there was instead a full modernization of the ww2-era Strv m/42 as the Strv m/74. Meanwhile, attention also turned to the lighter innovative French AMX-13, with plans for license production as the X tank, but in 1953 the British Government agreed to allow the Centurion for purchases and negotiations were back on tracks. After purchasing two Marks (Strv 81 and 101), the former modernized as the Strv.102, the last were maintained in service in the 1990s as the Strv.104. One unit trained on these as recently as 2000 but it was demobilized as the Swedish Leopard 2 (Strv 122) has been a standard replacement.
strv-104-youtube
Strv-104 (Youtube)

Strv.81

The same year, 80(100?) Mk3 of the reserve were purchased, entering service in Skåne. It was classed as a heavy tank and designated Strv 81. The latter was unmodified apart for minor details proper to Swedish use. It was delivered all in imperial measurements and Pre-NATO threading made the screws incompatible with the later strv 101. It was then armed with the 90 mm ROF 20-pdr gun of the first generation and was relatively underpowered with a 640hp engine, for a top speed of 34-35 km/h on flat. In 1956, 150(160?) more tanks Mark 3/5 were purchased, all armed with the improved 20 pdr type B, also designated Strv.81. In both cases, the only change was the mounting of Swedish radios.
stridsvagn_102_revinge_2013
Strv-102 at Revinge, 2013. The Strv-101/102 were hardly distinguishable

Strv.101

In 1958 the third batch of about 110 Centurions was purchased, but this time of the Mark 10 type. They were all armed with the soon-to-be-legendary Royal Ordnance Factory L7 105 mm rifled gun. In addition, they had a more powerful engine, 120 mm of frontal armor and NATO-standardized equipment, Swedish instrumentation and Radios. Just like in Great Britain, sub-types appeared when it was decided to upgrade the older Mark 3 and 5s. In the 1980s also appeared the Stridsvagn 101R, upgraded with laser rangefinder equipment.

Strv.102

In the early 1960s, it was decided to standardize the Strv-81s to the 101 standard, starting with the main gun, the L7 105 mm, an operation performed in 1964–1966. Eventually, in the early 1980s, they were upgraded again to the late Mark 10 type, with a newly improved armor and at the same time appeared the Stridsvagn 102R upgraded with laser rangefinder equipment.
stridsvagn_102_revinge_2014
Strv-102 at Revinge in 2014

Strv.104

The last wave of upgraded came with the modernization of a batch of 80 Strv.102 with a brand new, more powerful diesel engine (see later) and upgraded laser rangefinder. But the biggest improvement came from the armor, over which was fit a series of ERA (Explosive Reactive Armour) blocks.

Strv.105/106

Two prototypes were built: One Strv.102R (105) with upgraded suspension and other elements, and another of the 101R type (106).

strv_104_ointres-se
Strv-104 showing its ERA blocks, part of the 1980s REMO (“REnovering och MOdifiering”) package.

Specifications of the Strv.104

Since this was the last and most interesting model, with more proper Swedish modifications than the others of the series, this will be the focus of our attention. Configuration remained identical to the British Centurion, with a standard crew of four: commander, gunner and loader (turret) and front-left driver in the hull. Combat weight was 54 tonnes.
In 1983-1987, Centurions underwent a midlife renovation and modification (REMO) including a night vision equipment, targeting systems, laser range finders, improved gun stabilization, barrel thermal sleeves and exhaust pipes, and more importantly reactive armor.
Mobility
The Strv.104 was given a brand new powerplant, in addition to the REMO package, this stands for Renovation/modification. This powerpack was also shared by the Sho’t Kal Alef, comprising a Continental diesel engine coupled with an Allison automatic gearbox.
Protection
Of course the Strv.104 inherited the Mark X improved armor, 120 mm thick, sloped armor (almost 200 mm of equivalent thickness)
The ERA bocks covered the glacis front, part of the ring, turret front and mantlet, turret roof, and sides over the metal side skirts. These were introduced in the 1980s with the REMO programme and were developed by the Swedish FFV Ordnance.
For active concealment, there were two banks of six-barrel smoke dischargers and two erectile illumination round dischargers on the rear of the turret roof.

The Strv-81-104 in active service

The Swedish Centurion was eventually retired for good in 1992, following specifications for a new MBT, followed by official comparative tests of the T-72, Leclerc, M1A1 and Leopard 2. The competition ended with the choice of the latter, with some local modifications (Strv-122). 350 Strv-81-104 Tanks has been in service covering most of the Swedish Cold War needs, together with the modernized Strv-74s and unconventional S-tanks of the same generation.

Links

The Swedish Centurion on part XIV
The Swedish Centurion on tanknudave
The Swedish Centurion on home4.swipnet
The Swedish Centurion on wikipedia
Walkaround on prime portal

Strv-104 specifications

Dimensions 9.6oa (7.7) x3.3 x2.9 m ( ft)
Total weight, battle ready 54 tons (xx Ibs)
Crew 4 (driver, cdr, gunner, loader)
Propulsion Teledyne Continental AVDS 1790 2DC V12
Suspension Torsion bar suspensions
Speed (road) 50 km/h (35 mph)
Range 480 km (300 mi)
Armament Main: 105 mm L7, 2x 7.62 mm m/39 LMG, 2 Lyran 71 mm light grenade launchers
Armor 120 mm frontal armour + ERA
Total production 80 (350)

Gallery

stridsvagn-104-ft
Strv-104

centurion-atgm
Strv-102R with ATGMs

Video


https://sv.wikipedia.org/wiki/Centurion_(stridsvagn)

strv-81-ss11-proto
Strv-81/102R prototype, with three SS-11 ATGMs. Normally this would be the other side.

strv-101
Strv-101

strv-104
Strv-104

Categories
Swedish armor

Infanterikanonvagn 91

Hello dear reader! This article is in need of some care and attention and may contain errors or inaccuracies. If you spot anything out of place, please let us know!

Sweden (1975)
Light Tank – 212 built

The Swedish cold war light tank

With the Infanterikanonvagn 91 abbreviated as Ikv-91 (for “Infantry gun carrying vehicle”) Hägglunds of Sweden signed one remarkable light tank of the 1970s. And it was even not intended for reconnaissance, but for infantry support, and designated as a tank destroyer. One of its possible influence was the Soviet PT-76. Specifications indeed included the Ikv-91 to be amphibious, a necessity in some regions with Taiga and winter snow. Its manufacturer was Hägglunds and Söner (now Hägglunds Vehicle AB) also responsible for the Pbv 302 APC. Indeed for cost issues, the light tank also reused many parts, including the roadwheels of this model. The first prototype was ready and tested in 1969, but others followed until production was approved in 1975 so it arrived at the time when light tanks started to be replaced by more versatile Infantry Fighting Vehicles.

Ikv91 Nb4776 at the military training field Uddevalla, Sweden.

Design

Protection and general configuration
The Ikv-91 was made of welded steel, with a sloped nose and turret front but flat sides and flat turret walls and rear. Specs of the armor remain unknown but were stated proof against 20-25 mm AP rounds on the frontal arc, both for the turret and hull. The running gear top was protected by rubber side skirts. Provisions were made also for extra add-on armor. Compartmentation was standard, with the driver in the hull’s left-hand side, with its own hatch opening left, and three vision blocks (central IR optional one), while the rest of the crew was located inside the turret in the center. The gunner was located to the right-hand side, with the commander behind and the loader on the left-hand side. Both the loader and commander had their own hatch opening backward and sights, but the commander had no proper cupola with peripheral vision. The loader had a cartridge ejection port at the rear of the turret. Additional storage was provided by an optional turret basket.
Armament:
The Infanterikanonvagn-91 core was its Bofors high-pressure chamber rifled 90 mm KV90S73 L/54 (model 1973) which had a +15° elevation and −10° depression. It was capable of firing either HEAT and HE rounds with an accuracy and velocity approaching the NATO L7 105 mm gun. The rounds were substantially lighter, but 59 could be stored. With a well-trained crew, the average rate of fire was 8 rounds per minute. The barrel had a thermal sleeve and a fume extractor. Although apparently it was not fully stabilized (compared to the later Ikv-105) it was assisted by a laser rangefinder, night vision and a computerized fire-control system for improved first hit capability. Secondary armament comprised two 7.62 mm Browning machine guns or m/39 machine guns (one coaxial, one roof-mounted), a bi-tube Lyran 71 mm light grenade launcher (optionally mounted on the turret) and two banks of six smoke grenade dischargers for concealment on the turret rear sides.
Mobility:
Mobility of the Infanterikanonvagn-91 was assumed by a powerful Volvo Penta model TD 120 A, a 4-step turbocharged straight six-cylinder diesel engine with a cylinder volume of 11.97 litres, which developed 330 hp at 2200 rpm for a favorable power to weight of 20.2 hp/tonne and a top speed in excess of 65 kph on flat. Off-road capabilities were excellent thanks to a relatively low ground pressure, large tracks, and large roadwheels (no return rollers) resting on independent torsion bar units. The drive sprockets were at the rear and idlers at the front.
Field trials showed it could climb a 60% slope, 30% side slope, 0.8 m vertical step, 2.8 m trench and swim at 7 kph. The Ikv-90 was indeed made fully amphibious, buoyant enough thanks to the hull sides cofferdams, to swim with a short preparation, including raising a trim vane folded on the glacis and setting up screens to protect water from entering the engine.

The Infanterikanonvagn 105

Plans were made to replace the Bofors 90 mm gun by a standard NATO equivalent 105 mm gun or even a TOW missile launcher. The former was made as a prototype in 1983 (Ikv 105) and tested but was seen less attractive as new vehicles were about to enter service like the Leopard 2 or CV-90. The Ikv 105 was marketed for export and evaluated by India and US Army. Compared to the IKv-91 it weighed 18 tons, was able to swim at 12 kph, and its Bofors 105 mm had a low recoil and was fully stabilized, coupled with a new FCS and SAAB IR sight. Both the gunner and commander had displays and gun control.

Service

The production span was quite short for an armored vehicle, just three years (until 1978). The 212 manufactured were given organically to infantry brigades, which had one company of 12 vehicles each acting as tank destroyers although they could naturally have been employed as reconnaissance vehicles. The 10th Mechanized Brigade also had two companies in the 1980s. They traded armor for armament range and mobility and therefore needed to “nail down” their opponents faster and at a longer range. After long years of service, the Ikv 91 was retired gradually in the late 1990s to the early 2000s. Its partial replacement was the CV90 (IFV) and Leopard 2.

Links

The Infanteriekanonvagn 91 on wikipedia
Walkaround on prime portal

specifications

Dimensions 6.41 (8.85oa) x3 x2.32 m (21 x9.8 x 7.5 ft)
Total weight, battle ready 16.3 tons (32.600 Ibs)
Crew 4 (driver, cdr, gunner, loader)
Propulsion Volvo Penta TD 120A, turbo six-cyl diesel 330 hp at 2200 rpm P/w 20.2 hp/t
Suspension Torsion bar beam suspensions
Speed (road) 65 km/h (40 mph)
Range 500 km (311 mi)
Armament Main: 90 mm KV90S73
Sec: 2x 7.62 mm m/39 LMG
2 Lyran 71 mm light grenade launchers
Armor 20 mm frontal arc estimated (0.8 in)
Total production 212

Ikv-91 in standard camouflage
Infantriekanonvagn-91 in standard camouflage.
Ikv-91 with winter camouflage
Ikv-91 with winter camouflage

Video

Gallery

Preserved Ikv-91
Preserved Ikv-91
blueprint
Blueprint of the Ikv-91
Ikv 91 at Puckapunyal museumIkv-105 test vehicles in field trialsIkv-91 in winter camouflageIkv-91 at Bovington museum

Categories
Swedish armor

Pansarbandvagn 301

Sweden (1961)
Armoured Personnel Carrier – 220 built

Based on a 1935 chassis

A bit provocating, this assertion is nonetheless true as the obsolescent light tank Stridsvagn M/41 was a license-built version of the Skoda TNH tank, from which the basic chassis design dated back from 1935. The previous troop transport in service with the Swedish Army then was the Volvo-Scania KP-Bil, a truck conversion which had its flaws like an open-topped compartment, barely compatible with overall protection and the new cold war NBC threats, or off-road capabilities. The Swedish Army then chose to “recycle” old hulls from the now discarded Stridsvagn M/41, and convert them instead as tracked APCs, the first in Swedish service. It was also Sweden’s first IFV (Infantry Fighting Vehicle).

Design of the PBV 301

Engineers from Landsverk had 238 Stridsvagn m/41 produced in 1942-44 at their disposal and comprehensively erased the superstructure and turret, and completely reworked the interior. A new superstructure was built above, with a sloped front glacis, sloped sides and a flat rear, equipped with large-two pieces access doors. The engine (a compact and more modern Svenska Flygmotor B44 gasoline giving 160 hp or 119 kW) was relocated to the front left side but was still partly accessible from the inside of the vehicle. There was no separation between the driver and commander’s seats and the infantry behind, 8 fully equipped infantrymen seated on folding seats with storage boxes under. The welded RHA armor was only 8 mm (0.3 in) at the thickest, providing protection against small arms fire and shrapnel.
The driver was seated on the left-hand side and the commander to the right, in échelon to the rear compared to the driver and facing rearwards when operating the remote controlled main weapon station. Both had armored flaps without sight slits but the commander had additional three vision blocks. The roof comprised a cupola for the commander to the left with six vision blocks and a smaller cupola to the left-rear for the crew, with four vision blocks. The engine exhaust was installed to the front left side, facing downwards. Storage boxes were welded to both sides. There was a large access trap at the lower front part of the glacis to access to the transmission, gearbox and fuel tanks. The main armament was a remote-controlled Bofors 20 mm automatkanon m/45B manned by the commander. The Pansarbandvagn 301 had no secondary armament, no amphibious capabilities nor NBC protection.

Variants

– 185 of the regular production version were delivered by Landsverk AB.
– 20 of the command vehicles version of Stridsledningspansarbandvagn (SLPBV) 3011 were also delivered.
– 15 of the forward artillery observation vehicles Eldledningspansarbandvagn (EPBV) 3012 were also delivered.

A short operational history

This APC was converted from the prototype built in 1959 and accepted in 1960 to 220 vehicles (including variants) and introduced into service in 1961. The Pansarbandvagn 301 was largely seen as seen as a transitional, stopgap vehicle until the model 302 was introduced. It replaced the Kp-Bil in the 1960s but was itself superseded and replaced fast in 1971, after only ten years of service.

Links about the Pansarbandvagn 301:

The Pansarbandvagn 301 on Wikipedia
Additional photos from the Pansarmuseet

Pansarbandvagn 301 specifications

Dimensions (L-w-h) 4.66 x 2.23 x 2.64 m (15.3 x 7.4 x 8.8 fts)
Total weight, battle ready 11.7 t (?? lbs)
Crew 10 (commander/gunner, driver, 8 infantry)
Propulsion S.Flygmotor B44 gas. 160 hp (119 kW) p/w 13.68 hp/t
Top speed 45 km/h (28 mph)
Range 300 km (190 mi)
Armament Bofors 20 mm automatkanon m/45B (0.7 in).
Suspensions Leaf springs
Armor Max 8 mm (0.3 in)
Production 185 (Pbv 301 only)


Pbv 301, with all doors and roof hatches opened. The latter served as improvised shield for firing in a standing position, hatches locked in place.
Pbv 301
Pbv 301. The 20 mm Bofors made it in effect an Infantry Fighting Vehicle.
Pbv 301
Pbv 301. No photos shows any camouflage for this serie.

Gallery Pbv 301

Revinge, 2013
Interior view from the rearside viewPreserved in SträngnäsPreserved in HässleholmPreserved in Sinsheim

Categories
Swedish armor

Stridsvagn 103

Sweden Sweden (1956)
Main Battle Tank – 290 built

The “S-Tank”, a historical landmark?

The Strv-103 is one of a kind, concentrating so many innovative solutions and new ideas into one vehicle, that to this day it has left an unmistakable imprint in tank design, according to most experts. It was a rather original solution to the unique national defense issues of Sweden during the cold war. Sweden chose to adopt the tank best suited for the landscape it was to fight on, this, in turn, produced an unconventional solution: a self-propelled gun used as a main battle tank, classed and recognized as one despite its obvious lack of a turret. It succeeded in this category by concentrating many technological breakthroughs that rendered this paradox possible.

Hello dear reader! This article is in need of some care and attention and may contain errors or inaccuracies. If you spot anything out of place, please let us know!

Strv-103 at the Saumur Museum

Development of the Strv-103

In the mid-1950s, the standard Swedish MBT was the British-built Centurion (Stridsvagn 81 to 104). But there were already proponents pushing for its replacement with a domestic tank. The consortium Landsverk, Volvo and Bofors proposed the KRV tank design, using a 155 mm smoothbore into an oscillating turret. It was eventually rejected as it was deemed to be too expensive, and the government turned once more to foreign designs. In the meantime, Sven Berge (of the Swedish Arms Administration) proposed the “Alternative-S” model based on the lowest possible silhouette, which would be far cheaper than the KRV and even some foreign designs. This design eliminated the turret, and the problems of gun elevation and depression found in vehicles without turrets were solved in an unorthodox way.
Berge came up with the idea of a fully automated suspension able to provide vertical motion to the gun, assisted by an automatic transmission. After the plans were submitted, Bofors was asked to build a prototype of the suspension and drive train, which was then successfully tested. In 1958 came an order for two first production prototypes which were completed in 1961. In the meantime, the army ordered an initial pre-production batch of ten tanks. After a few modifications, the “Alternativ S” was put into service as the Stridsvagn 103 (the number stands for being the 3rd tank armed with a 10 cm main gun in service). The full batch production was placed in 1965 and the first deliveries spanned from 1967 to 1971, with 290 machines.
Tank museum Munster

Design

The design was as radical as its roots suggest. Instead of having a standard suspension and some limited elevation and traverse as well as a propensity to strain the transmission when maneuvering like with many casemate-gun vehicles, the S-Tank was given hydropneumatic suspension and a fully automatic transmission. The gun was entirely fixed inside the turret, which allowed the driver in practice to be also the gunner when aiming the gun. The fixed gun also meant that the hull could be made as low as possible. There was a catch, however: this system forbade firing on the move. This was not seen as a great disadvantage, as practice had proven with the Centurion that the best accuracy was obtained while stationary.
The gun, for practical reasons, was a Bofors 105mm L/62, firing the same ammunition as the British 105 mm L7 (50 rounds in store). It had an autoloader (placed at the rear bottom end) to allow a 15 rounds/minute and to reduce the crew to only two. Spent cartridges were ejected through a flap in the rear. The commander normally passed target information to the driver/gunner, which then aimed the gun and fired when stopped, but the commander had duplicate controls and override, plus control over smoke dischargers, in case of need for immediate action. There was enough room for a driver/radio operator facing rearwards, who could drive the tank in reverse if needed, keeping the front armor always pointed to the direction of the enemy.
Consoles were futuristic in appearance and were designed to be ergonomic. For aiming, the tank could traverse smoothly and precisely, despite obstacles in its path, and swivel on its own axis. The elevation/depression range was 22°, better than most MBTs of the time.
In addition, the commander and driver both had the same set of sights but also controls to fire the gun or drive the tank. That also was very specific to the S-Tank. Secondary armament comprised two fixed 7.62 mm KSP 58 machine guns and one anti-aircraft 7.62 mm KSP 58 machine gun placed on the commander’s cupola. A gyro-stabilized cupola model was added during production. In addition, slat armor could be added on the front to help defeat HEAT rounds. This armor was long kept secret.
S-Tank
The hull was indeed also radical, and while it was made of standard RHA, and still relatively thick (90-100 mm on the front glacis) it formed such an angle that the thickness equivalent in direct fire was far greater. The hull could be lowered to a further 13 cm by adjusting the suspension. In addition, it had a folded dozer blade under the front hull to dig itself in the ground (acting also an extra protection). Placing the tank in a hull down position would have given a very little apparent height and quite a limited visual profile to the enemy observers. It was for example 3.5 inches lower than the T-64, but the latter paid for this extremely low silhouette with a very cramped interior.
The Strv-103 was fully amphibious, with a built-in floating screen and could swim after 20-25 min. of preparation. The speed when swimming was around 6 kph (3.7 mph), using the tracks motion to provide some steering. The changes included a new and upgraded frontal armor. Slat armor could be mounted at the front to help defeat HEAT rounds, but it was only to be fitted in the event of war because of its secrecy. Lately, nine jerry cans were added on each side, acting like add-on armor.

The powerplant also was tailored to the hull and was quite original. It was an arrangement of two engines: A flat 240 hp Rolls-Royce K60 opposed-piston diesel for slow cruising and maneuvering when aiming, plus a 300 hp Boeing 502 turbine for high-speed travel and cruising on rough terrain. The latter was found in practice underpowered and soon replaced by a Caterpillar turbine (490 hp) on the B version. This was also the first use of a turbine engine in a production tank, worldwide. With the Caterpillar, the combined output of the powerplant was 730 hp. This provided an 18.3 hp/tonne power-to-weight ratio, a top speed on flat of 50 kph (31 mph) and a 390 km total range (240 miles). The diesel engine was coupled to 2 forward and 2 reverse speeds.The gas-hydraulic hydro-pneumatic suspensions were also very innovative. It served four large coupled rubber-clad roadwheels. There was a drive sprocket at the front and idler at the rear. Due to the narrow space allocated to the nose, the transmission was placed here, right before the driver. This suspension allows the gun (and whole hull) to depress enough in a hull down position that it presents virtually no frontal surface to the enemy while being still capable to spot and destroy opposing targets.

Variants

Strv-103 B

After the 80th tank delivered, operations showed the early production model was somewhat underpowered after all the added modifications compared to the prototype. To keep the performances up, a new Caterpillar 553 turbine was adopted. The latter could deliver 490 hp (365 kW) as compared to Boeing’s 300 hp. The first batch was later called Strv-103A and then upgraded to the “B” standard powerplant.

Strv-103 C

After 15 years of service, it was envisioned an upgrade to keep pace with advances in gunnery in the east. An improved fire control system was installed, but also a dozer blade for all vehicles (one per platoon before). In 1987-88 the aging Rolls-Royce diesel was replaced with 290 hp (216 kW) Detroit Diesel, with additional fuel tanks. The first-hit capability was much improved by the addition of a new laser rangefinder. Reactive or appliqué armor was studied in the early 1990s but this prospect was never carried out as it was decided to retire the model in favor of the Strv-122 (Leopard 2).

Strv-103 D (prototype)

This last upgrade was performed in the mid-1990s, with a new fire-control computer, Gunner & commander thermal sights for low-visibility and night fighting, and a passive light enhancer for the driver. The suspension and engine receive the adjustment and minor modifications. This unique prototype was also even tested under remote control.
4-view drawing

Operational history

The S-Tank was intended to deal with Soviet tanks but also to be suited for suited a landscape alternating rolling farmland in the south and high forests and tundra in the north, frozen or soggy depending on the season. It was to be embedded into earthen ditches, facing the enemy, then retire in fast reverse to join another tactical position. The whole purpose of the “S-Tank” was to fit in a defensive positioning doctrine.
The last Strv-103C was retired in 1997. They were used for training. Nowadays, the single Sstrv-103D and several type C are displayed at the Swedish tank museum Arsenalen, all in running order. The Strv-103 was never tested in combat and never inspired another similar concept, although many of its innovations can be found on modern tanks, like the turbine engine in the M1 Abrams and T-80.

Video: Documentary on the S-Tank

Links about the Strv-103:

The Strv-103 on Wikipedia
Video archive of live test fire (Sw with En subtitles) showing the S-tank protection level

Strv-103 Lynx specifications

Dimensions (L-W-H) 8.99m (7.04m without gun) x 3.63m x 2.43m
(29’5″ (23’1″) x 11’9″ x 7’10” ft.in)
Total weight, battle ready (B/C) 39.7/42.5 tonnes (15 600 lbs)
Crew 3 (commander, gunners, rear driver/radio)
Propulsion RR K60 diesel 240 hp (A-B) Detroit diesel 6V53T 290 hp (C)
Boeing GT502 gas turbine, 300 hp (A) Caterpillar 553 gas turbine, 490 hp (B-C)
Top speed 50 km/h (31 mph)
Range 390 km/290 mi
Armament Main: 105 mm Bofors L/62 50 rounds.
3 x KSP 58 cal 0.3 (7.62 mm) LMGs (1 AA)
Armor From 90 to 100 mm classified (3.5 to 3.9 in)
Production 290

Gallery

S-tank in a public display, 2013S-tank in a public display, 2013S-tank in a public displayS-tank in a public display

Strv-103A
S-Tank of the first serie, 1966.
Strv-103B
Strv-103 B (1970)
Strv-103C
Strv-103 C in the early 1990s