Categories
WW2 German prototypes

VK30.01(D) and VK30.02(M) – Panther Prototypes

Nazi Germany (1942)
Medium Tank Prototypes – 4 Built

“…I was quite startled, however, by an unusual event in connection with the tank in question. In the spring of 1941, Hitler had given his express permission that a Russian officer’s commission be permitted to visit our tank training schools and armor production facilities, and had ordered that the Russians be allowed to see everything. During this visit, the Russians, when shown our Panzer IV, simply refused to believe that this vehicle was our heaviest tank. They repeatedly claimed that we were keeping our newest design from them, which Hitler had promised to demonstrate. The commission’s insistence was so great that our manufacturers and officials in the Waffenamt finally concluded that the Russians had heavier and better types than we did…”

– General Heinz Guderian, Erinnerung eines Soldaten/Panzer Leader

This should have been the first warning sign to the Germans that the Soviet Red Army was not as far behind technologically as they had believed. In 1941, World War II was in full swing, Germany had swept through most of Europe, and with the Channel blocking their advance into England, the only way left to go was east, turning on their one-time ally, the Soviet Union.

As early as July of 1940, Hitler had been thinking about invading the Soviet Union; he was counting on their obsolete and disorganized military to quickly fall to the blitzkrieg as the rest of Europe already had. Although Germany and the Soviet Union had signed a non-aggression pact in 1939, both countries still held a distrust of one another. This would be validated on the Soviet’s part when the Germans invaded on June 22nd, 1941.

At the start of Operation Barbarossa, the German invasion of the Soviet Union, Germany’s primary tanks were the Panzer III and the Panzer IV, both of which were mid-1930s designs. Even so, they were still seen as superior to anything the Russians could field. Indeed, the Panzer III’s 3.7 cm KwK 36 cannon would have no trouble at all punching through T-26s and BT tanks; but time had not stood still since the Germans were last allowed to examine the Soviet’s tanks. Whether through arrogance or ignorance, the Germans had failed to realize that Soviet tank development in 1941 had far outpaced their own. Only one day into Operation Barbarossa they would see this firsthand.

June 23rd, 1941, would see the combat debut of the T-34 and KV-1, the latter all but impregnable to German 3.7 cm and 5 cm anti-tank guns. The T-34 in particular was seen by the Germans as a massive leap forward in tank design, combining maneuverability, a powerful cannon, and good protection on account of its comprehensive use of sloped armor. The appearance of these new enemy tanks left the German army scrambling to find a solution to defeat them. The companies of Henschel and Porsche had been involved in work on a heavy breakthrough tank since early 1937 and late 1939 respectively, but this had not been seriously pursued up until this point. However, the appearance of the new Soviet tanks, and the promise of even better ones to come, led to much more focus being laid on the design that would eventually become the Tiger. Moreover, a new, more modern tank design was needed, incorporating the advantages of sloped armor but retaining the maneuverability that had made the Panzer III and IV so successful.

On July 18th, 1941, Rheinmetall-Borsig was contracted to develop a new tank cannon specifically to defeat the heavy Soviet armor encountered on the Eastern Front. It was to be capable of penetrating 140 mm (5.51 in) of armor at 1 kilometer (0.62 miles). They were also asked to develop a turret to house it. This gun and turret was to be mounted on the VK45.01(H2) [Tiger], but that project instead went with an 8.8 cm gun in a different turret, leaving the 7,5cm gun for what would become the Panther. For this purpose, the turret would be redesigned, becoming more squat and losing the side hatches and rear machine gun mount.

The 7.5 cm cannon was originally designed with a barrel length of L/60, or 60 calibers; this gave it a barrel length of 4,500 mm (177.2 inches). However, as the gun turned out to be slightly anemic, the barrel length was increased to L/70; resulting in a length of 5,250 mm (206.7 inches). This gun would be standardized as the 7.5 cm KwK 42 L/70.

The Rheinmetall-Borsig turret and 7,5cm cannon, here still 60 calibers in length, mounted on the VK45.01(H2) wooden mockup. To the left of the VK45.01(H2) appears to be another Tiger hull mockup, with another version of the turret that more closely resembles the turret that would be used on the Panther. Source
Rear view of the Rheinmetall-Borsig turret and 7,5cm cannon mounted on the VK45.01(H2) wooden mockup. Source

Upon experiencing the shock of encountering the T-34 firsthand at the Battle of Mtsensk on October 6th, 1941, General Heinz Guderian, the commander of the 2nd Panzer Army, sent for a commission to come and study the T-34 tanks that had been knocked out, and to talk to the men that had been involved in fighting them to determine what advantages the Soviet tanks possessed over the German vehicles, and what could be incorporated into new German designs.

The Special Armor Investigation Committee was led by Oberst Sebastian Fichtner, head of Waffen Prüfämter (Weapons Testing Office) 6, or Wa. Prüf. 6, the German organization in charge of tank development. The team included Heinrich Ernst Kniepkamp (senior engineer at Wa. Prüf. 6), Major Ruden (also of Wa. Prüf. 6), Otto Wunderlich (representing Daimler-Benz), Erwin Aders (representing Henschel), Director Dorn (representing Krupp), Engineer Oswald (representing Maschinenfabrik Augsburg-Nürnberg (M.A.N.)), Ferdinand Porsche (representing Porsche), Engineer Zimmer (representing Rheinmetall-Borsig), Oskar Hacker (representing Steyr), and Walter Rohland (representing Vereinigte Stahlwerke).

The commission arrived at the front on November 18th, 1941, and stayed until the 21st. During this time they heard the experiences of officers of the engineering corps, as well as suggestions from a tank repair company on how best to improve air filters to deal with the dusty conditions of the Russian summer. They examined a recent battlefield and met with repair and recovery personnel of the XXIV Panzer Korps.

While at the front, the commission examined several knocked out T-34s. They quickly determined three design advantages the T-34 possessed over the Panzer III. The first, which has been pointed out already, was the sloped armor, which afforded greater protection than flat armor of the same thickness. The second was the suspension; the T-34 had five large roadwheels and no return rollers, giving a smoother ride and greater suspension travel. In addition, its wide tracks gave low ground pressure, ensuring that it did not bog down on soft terrain. The third promising feature of the T-34 was the long gun barrel overhanging the front of the tank. This had previously been avoided by German tank designers as it could complicate maneuvering in forests and cities. A longer barrel affords more time for the shell to accelerate before leaving the cannon, resulting in better muzzle velocity and thus better armor penetration.

General Guderian laid out for them the issues experienced so far and requested the following:

  • Current tanks should be up-gunned.
  • New tanks must be made with wider tracks and lower ground pressure to deal with the Rasputitsa mud. Tanks must be able to drive cross-country and on unimproved trails in all seasons.
  • The new tank must have heavier armament, improved armor protection, and higher tactical mobility compared to previous designs. It should also have a more powerful motor and maintain a high power-to-weight ratio.

With their work done, the commission returned to Germany to distribute their findings.

Sebastian Fichtner was opposed to starting development on an entirely new tank, as the VK24.01, the fruit of the previous VK20 project to replace the Panzers III and IV, was nearly completed. However, the Reich Minister for Armaments and Ammunition, Fritz Todt, disregarded Fichtner’s concerns and gave the go-ahead to start work on a new tank.

Wa. Prüf. 6 therefore put forth a design competition on November 25th, 1941, issuing contracts to the firms of Daimler-Benz and M.A.N. to develop a new tank with the following parameters:

  • Combat weight of 30 to 35 metric tonnes
  • Maximum width of 3,150 mm (10’4’’)
  • Maximum height of 2,990 mm (9’9.7’’)
  • Minimum ground clearance of 500 mm (19.7 inches)
  • 60 mm (2.36 inch) thick frontal armor, sloped at 35° from the horizontal
  • 40 mm (1.57 inch) thick side armor, sloped at 50° from the horizontal
  • 16 mm (0.63 inch) thick floor and roof armor
  • Main armament was to be Rheinmetall’s 7,5cm cannon
  • Engine expected to be between 650 and 700 metric horsepower
  • Steering mechanism was expected to be the L 600 C unit
  • Speeds of between 4 kph (2.5 mph) in lowest gear and 55 kph (34.2 mph) in top gear
  • Cooling system capable of operating in temperatures up to 42° C (107.6° F)
  • Capable of running for 5 consecutive hours

The design was expected to be ready by Spring of 1942.

Remarkably, on the very same day the new design competition was ordered, M.A.N. had drafted a new version of their VK20.02 incorporating sloped armor (Drawing No. Tu 13947). This design strongly resembles M.A.N.’s later design for the VK30.02 [Panther], and even more so the little brother of this design, the Gefechtsaufklärer Leopard. Assuredly this is no coincidence, as both M.A.N. and Daimler-Benz used experience gained with the VK20 series of tanks in creating their VK30 designs. Source: Panzer Tracts 5-1

Development of the M.A.N. Design


Illustration of the M.A.N. design by Andrei Kirushkin

In response to a postwar inquiry as to what inspired the Panther design, M.A.N. stated that, “Previous steps were design studies conducted under the names VK20.01, VK24.01, and VK30.01. Based on requirements established by Wa. Prüf. 6, they were reworked to slope the walls like the Russian design [T-34].” No other mention of VK24.01 or of a VK30.01(M) have been found. If they existed at all, they have been lost to time.

M.A.N.’s design team, led by Paul Max Wiebicke, utilized the turret developed by Rheinmetall-Borsig for mounting the 7.5 cm cannon. The turret was placed in the center of the tank as far back as possible to reduce the length of the barrel overhanging the front of the tank. Secondary armament consisted of two 7.92 mm (0.31 inch) MG 34 machine guns. One was mounted coaxially to the right of the main cannon, and the other was given to the radio operator to fire through a bow position.

Crew layout was typical for German tanks, driver and radio operator/machine gunner in the hull, with the driver on the left and the machine gunner on the right; gunner, commander, and loader in the turret, with the gunner and commander on the left and loader on the right of the gun. Hatches were placed in the roof above the driver and radio operator; this provided an easier means to evacuate wounded crew members than the side hatches the Daimler-Benz design used. An escape hatch for the turret crew was placed on the rear of the turret.

Frontal hull armor was 60 mm (2.36 inches) thick, sloped back by 55° from the vertical (both upper and lower glacis). Side hull armor was 40 mm (1.57 inch) thick, vertical behind the tracks and sloped back by 40° above them. The rear of the hull was 40 mm (1.57 inch) thick with a 30° reverse slope. The hull roof and belly were both 16 mm (0.63 inch) thick at 0°; as was the turret roof, although the forward section was slightly angled, at 85° from the vertical. The front of the turret was 80 mm (3.15 inches) thick, sloped at 12°; the sides and rear were 45 mm (1.77 inch) sloped at 25°. The overall dimensions of the design were 6.839 meters (22’5.3’’) long excluding gun barrel, or 8.625 meters (28’3.6’’) including the barrel; 3.270 meters (10’8.7’’) wide, and 2.885 meters (9’5.6’’) tall including the turret, or 2.314 meters (7’7.1’’) tall excluding the turret.

The powerplant was originally suggested to be a 650 hp liquid-cooled two-stroke V8 diesel engine being developed at M.A.N.’s Augsburg plant. Despite the fact this engine had been in development since 1940, originally being designed for 450 hp output, Fichtner urged M.A.N. to push for 700 hp. Development of this engine was slow and it became too large and heavy, eventually being abandoned. Instead, M.A.N. went with Maybach’s HL 210 engine; bringing in Maybach to do the work of mounting the engine and designing the cooling system and other accessories. Air for the engine was sucked in from under two protective domes mounted in the middle of the engine deck, while two fans, one on either side of the engine block, circulated air through the radiators. Interestingly, the fans were driven by bevel gears and shafts, as opposed to fan belts. The Maybach engine would power a driveshaft passing through a 250×250 mm (9.8 inch) square shroud under the fighting compartment, and into a front-mounted transmission, as was common for German tanks. The transmission was an AK 7/200 unit of the standard mechanical type. It was coupled to an L 600 C hydraulic, controlled differential, regenerative steering mechanism that was also used on the VK45.01(H) [Tiger]. M.A.N. had originally wanted to use solid disk brakes for steering but was told that these would cause issues with heat from friction.

The VK30.02(M)’s suspension consisted of three rows of 860 mm (33.9 inch) diameter roadwheels, mounted on double torsion bar suspension. With tracks that had two rows of guide horns, one row of wheels ran on the outside of either row of guide horns, and the center row of wheels ran between them. The roadwheels of the center row were double units, resembling two normal roadwheels bolted together. The leading axle carried a central double wheel. The second axle carried a pair of single wheels flanking the first roadwheel on either side; this was repeated four times down the length of the suspension. This design was described as an ‘interleaved eight wheel setup’, as there were eight axles, even though each axle carried more than one wheel. Hemscheidt HT 90 shock absorbers were mounted to the second and sixth axles. Suspension bumpers had to be placed under the first, second, and seventh roadwheel arms to keep the roadwheels from traveling too far, overloading, and breaking the torsion bars. This limited suspension travel to a still impressive 510 mm (20.1 inches).

This complicated suspension system, combined with a wide track (660 mm (26 inch)) gave the tank a smooth ride and a consistent, low ground pressure of 0.68 kg/cm2 (9.67 psi). Although this type of suspension was already being used on half-tracks and on the Tiger tank, there was still trepidation from some regarding its use over more traditional designs. Equally, there were people who felt it was the way forward, such as Sebastian Fichtner and Heinrich Kniepkamp.

The VK30.02(M) carried 750 liters (198.1 gallons) of fuel, giving it an impressive projected on-road range of 270 km (167.7 miles) and an off-road range of 195 km (121.2 miles)*. Top speed was 55.8 kph (34.7 mph) and sustained road cruising speed was 40 kph (24.9 mph). The design was capable of a vertical step of 826 mm (32.5 inches) and a gradeability of 35°. Ground clearance was 500 mm (19.7 inches). The floor space of the fighting compartment was calculated as 7.26 square meters (78.1 square feet), but this did not include the steering mechanism, transmission, and other components, which if factored in would reduce the overall fighting space dramatically.

Shortly after work started on the VK30, M.A.N. was also tasked with creating a light scout version of the tank; this would become the VK16.02. The VK16.02 generally resembled a smaller version of the VK30.02(M), and very strongly resembled the VK20.02. In January 1942, Wa. Prüf. 6 transferred development responsibility for the VK16.02 to MIAG, to allow M.A.N. to focus on the VK30.02. In theory, Daimler-Benz also would have been developing a version of the VK16.02 based on their own tank, however no documentation regarding this survives.

On January 22nd, 1942, Paul Max Wiebicke and Otto Meyer (the General Manager of M.A.N.) met with Fichtner, Kniepkamp, Oberst Joachim von Wilcke, and a Major Crohn (the latter two also being members of Wa. Prüf. 6, although their roles are unclear) to discuss their VK30 design. The M.A.N. representatives reported that although they had settled on 32.5 metric tons as the weight of their design on December 9th, 1941, changes to the design had increased the projected weight to 36 metric tons. Wa. Prüf. 6 had apparently already been informed of the change, and constructed the scale model of the M.A.N. design so to reflect this. Wiebicke and Meyer were also shown the scale model of the Daimler-Benz design at this time, remarking that it was “very attractive”. The two tank models were to be shown to Hitler at a meeting at his headquarters the next day, on January 23rd. During the meeting on the 23rd, Fritz Todt decided that another meeting between the two companies should be held, so that the two designs could be standardized against each other. The date for this was set as February 2nd, 1942.

The scale model of the M.A.N. design. Source

While the steering mechanism for the VK30 was intended to be the L 600 C, M.A.N. had been developing simplified alternative designs, claiming that only by using their simplified steering mechanism could they build their tank with a pointed front hull. Wa. Prüf. 6 agreed to this, as long as the steering mechanism was ready before August 1942.

With most people of influence preferring the Daimler-Benz proposal, M.A.N. decided they needed to do something to make their design more appealing. What they came up with was sealing the engine compartment with a rubber lining to allow deep wading. With the engine compartment watertight, it would be able to operate underwater so long as the air intake on the top of the engine deck wasn’t submerged. The radiators, which were mounted vertically on either side of the engine, were not encompassed by this watertight compartment; instead they were exposed to the water whereby they could radiate heat. Because the cooling system was designed to flood whenever the tank entered water, all parts involved had to be impervious to water damage. All that had to be done to ready the tank for deep wading was shutting off the engine fans, which could be done from the driver’s position, and closing open ports, such as the air intake covers. Unfortunately, as would be discovered later, the rubber that kept the water out was also very good at keeping heat in. Heat buildup in the engine, from a wading system that was never even requested, would lead to many breakdowns and issues before it was fixed.

On February 2nd**, Paul Wiebicke, as well as Friedrich Reif (another worker from M.A.N.), went to the Heereswaffenamt building in Berlin to meet with Fichtner, Kniepkamp, von Wilcke, Crohn, and the design team from Daimler-Benz. When they arrived, they were informed that the meeting with Daimler-Benz had been cancelled, as Wilhelm Kissel (head of the Daimler-Benz board of directors) had managed to convince Reichsminister Todt to end the collaboration between M.A.N. and Daimler-Benz, and to allow Daimler to start work on building their prototypes. Regardless, the M.A.N. team had a constructive meeting regarding their tank design, and Sebastian Fichtner reassured them that Daimler was only being given permission to construct prototypes, not that they had been declared the winner of the competition. However, only a few days later, on the evening of February 10th, Fichtner again spoke to the M.A.N. representatives and informed them that after further discussion, Todt had approved the Daimler-Benz design for mass production.

**Germany’s Panther Tank gives this date as February 3rd, while it is in agreement with other sources that the meeting was supposed to take place on February 2nd. This could be a typo, but it is also possible the meeting had been postponed a day, before being cancelled.

The trip to Berlin had not been a total loss however, as M.A.N. was able to submit their final design to Wa. Prüf. 6, only one day after Daimler-Benz had done the same. Even though it was their ‘final’ design which they submitted as their entry, they were still making changes to it, some details of which were discussed at this meeting. The previous requirement that the M.A.N. design needed to be able to use the Daimler-Benz diesel engine was dropped, on account of the fact that cooperation between the companies was ended. Wiebicke and Meyer knew that Daimler wanted to deliver their first prototype by May of 1942, so they declared M.A.N. would also make this promise. Minor changes to the design suggested by Wa. Prüf. 6 had been incorporated or clarified by February 20th. The winner of the VK30 competition would be chosen following a presentation of the two designs in Berlin on March 3rd.

Development of the Daimler-Benz Design


Illustration of the Daimler-Benz Design by Andrei Kirushkin

Daimler-Benz’s VK30 design was a much closer copy of the T-34 than M.A.N.’s design. It retained the all-round sloping armor, forward mounted turret, and rear-mounted transmission – a feature uncommon in German tanks. The VK30.01(D) was armed with the Rheinmetall 7.5 cm cannon as per Wa. Prüf. 6’s design requirements, however Daimler opted to go with their own turret design instead of using the one developed by Rheinmetall. Secondary armament was identical to the M.A.N. design, two 7.92 mm (0.31 inch) MG 34 machine guns, one mounted coaxially to the right of the main gun, and another fired by the radio operator through a slot in the hull. Daimler-Benz’s turret had a turret ring diameter of 1600 mm (63 inches), 50 mm (2 inches) less than that of the Rheinmetall turret used on M.A.N.’s design; this would be its downfall.

Frontal hull armor was 60 mm (2.36 inches) thick, sloped back by 55° from the vertical (both upper and lower glacis). Side hull armor was 40 mm (1.57 inches) thick, vertical behind the tracks and sloped back by 40° above them. The rear of the hull was thicker than the sides, 50 mm (1.97 inches) sloped at 25°. The turret roof, hull roof, and belly were all 16 mm (0.63 inch) thick. The turret was sloped 30° all around, with frontal thickness of 80 mm (3.15 inches) and sides and rear of 45 mm (1.77 inches). The overall dimensions of the design were: 9.015 meters (29’6.9’’) long (including gun barrel), 3.280 meters (10’9.1’’) wide, and 2.690 meters (8’9.9’’) tall.

The VK30.01(D)’s suspension was similar to the suspension of the M.A.N. design in that it consisted of four sets of interleaved roadwheels, arranged in three rows. These roadwheels were 900 mm (35.4 inches) in diameter. The roadwheels of the center layer were built differently to the inner and outer layer wheels. Rather than being two single wheels joined together, as in the M.A.N. design, they had a groove down the middle, to accommodate the single row of guide horns on the tracks. Each set of roadwheels, meaning the leading central wheel, and the single wheels that flanked it on either side, was supported on its own U-shaped rocker bar. There were four such units on each side of the tank, each unit being connected to the hull by a suspension arm, the end of which opposite the rocker bar rested in a square bracket bolted to the side of the hull. Two of these brackets existed per side, with the forward one supporting the front two suspension units, and the rearward one supporting the rear two suspension units.

The suspension itself was leaf springs; three bundles per side. The first suspension unit was sprung on a small leaf spring bundle, bolted to the hull forward of the first square support bracket. The central two suspension units were each sprung on one side of a large central leaf spring bundle, mounted between the two support brackets. Finally, the rear suspension unit mirrored the first, and was sprung on another small leaf spring bundle, rearward of the second support bracket. The leaf spring suspension had the advantages of being easy to repair and maintain, and was already familiar to tank crews.

Relatively narrow tracks (540 mm (21.3 inches)) gave the 35 metric ton tank a ground pressure of 0.83 kg/cm2 (11.8 psi). The design was capable of a vertical step of 730 mm (28.7 inches) and a 40° grade, 5° better than the M.A.N. design. Ground clearance was 530 mm (20.9 inches).

VK30.01(D) suspension models, made by Tanks Encyclopedia’s own C. Ryan

Power would be provided by a Daimler-Benz MB 507 water-cooled V12 diesel engine, working through a rear-mounted KSG 8/200 hydraulic-assist transmission with an L 600 C hydraulic, controlled differential, regenerative steering mechanism. This transmission, developed jointly between Daimler-Benz and Ortlinghaus, incorporated a hydraulic multi-plate clutch, which afforded smooth gear changes and was easy to use. This choice of transmission was influenced by Daimler-Benz’s previous experience with the VK20.01(D). However, the hydraulic system had downsides as well; it was rather long compared to similar mechanical transmissions, and was not widely used. The only experience German heavy industry had with this type of transmission at the time was in small diesel switcher locomotives. To keep the tank compact, the engine was offset to the starboard side, with the output facing forward, from whence the powertrain was turned around and went through the transmission, which was mounted beside the engine.

VK30.01(D) engine-transmission layout blueprint. Source

The VK30.01(D) could carry 550 liters (145.3 gallons) of fuel, giving it a projected on-road range of 195 km (121.2 miles) and an off-road range of 140 km (87 miles)*. It also carried additional fuel tanks on the rear of the hull that could be jettisoned before going into battle. These auxiliary fuel tanks were likely intended to offset the fact that the M.A.N. design had a 200 liter (52.8 gallon) internal fuel capacity advantage over the Daimler-Benz design. Top speed was 56 kph (34.8 mph) and sustained road cruising speed was 40 kph (24.9 mph).

Cooling was provided by air sucked in through the tops of the protrusions on either side of the hull behind the turret. The air was passed over laterally-mounted radiators on either side of the engine and exhausted out the back. Four fans circulated air to the engine, one powered directly by the engine and the other three via V-belts. For deep wading, all hatches were sealed and air inlets and outlets would be closed off from the outside by valves. This would leave the engine running uncooled, giving a running time of a mere ten minutes before damage started to occur.

Crew was to consist of five men, as usual for German tanks; driver, radio operator/machine gunner, gunner, loader, and commander. Two convenient side hatches were provided in both the hull and turret to allow the crew to escape should the tank be knocked out. Because the turret was mounted so far forward, it was considered moving the driver into the turret with the rest of the crew, but after the initial design study this idea was not pursued. The area of the fighting compartment, from the engine firewall forward, was calculated as 6.43 square meters (69.2 square feet).

The scale model of the Daimler-Benz design. Source: Peter Chamberlain

On the 28th and 29th of January, 1942, Wilhelm Kissel and Richard Oberländer (technical manager of Daimler-Benz Werke 40, the main Berlin-Marienfelde plant) met with Reichsminister Todt and Sebastian Fichtner to discuss their proposed tank design. Fichtner pointed out that Daimler’s design had narrower tracks than M.A.N.’s; he also stated that he believed torsion bar suspension was superior to leaf spring suspension, as torsion bars allow greater internal width of the hull. The Daimer representatives disagreed with him on the superiority of torsion bars, as leaf springs allowed their design to be 200 mm (7.9 inches) lower than if it had used torsion bars, and leaf springs did not require the complicated shock absorbers that torsion bars did. Daimler believed that because their track had longer length in contact with the ground their design still had better ground pressure than the M.A.N. design, despite having narrower tracks. However, in actuality the track length in contact with the ground for both the VK30.01(D) and VK30.02(M) was the same, 3,920 mm (154.3 inches).

When recounting this meeting after the fact, Daimler representatives said that, “When compared to the competition, our tank with the longer suspension has improved performance when rolling over uneven terrain, crossing trenches, and climbing obstacles.” One interpretation of this statement is that the Daimler representatives were speaking of the aforementioned belief their tank had a longer track run than the M.A.N. design; however, another interpretation is that this statement seems to imply that Daimler had multiple suspension designs. It is possible that this is the explanation for why the unfinished chassis seen at the end of the war has return rollers, while no other depiction of the VK30.01(D) is shown to have them. The author puts forward the theory that the VK30.01(D), as it is most commonly depicted with no return rollers, is the “standard model”, while the unfinished chassis was to be built with the aforementioned “long suspension”, which must have necessitated return rollers by placing the roadwheels further from the drive sprocket.

During this meeting, the rear-mounted transmission was discussed at length; Fichtner was opposed to this feature as it could lead to tracks being thrown. (All the way back in 1928, the Germans had experienced this problem with the original Leichttraktor. They found that the rear-mounted transmission would cause the track to be “thrown”, or unseat itself from the drive sprocket. To correct this they instead went to front-mounted transmissions and stuck with them until the end of the war.) Daimler felt that wherever the transmission was mounted, there was no difference in the reliability and handling of the tank, as shown by Russian tanks. On this topic, Daimler-Benz representatives said, “Employment of the rear drive provides additional crew space and also a better slope to the hull front armor, which is especially important in preventing penetration of armor-piercing shells. If no option is possible for the choice of motor, our design also allows the installation of the Maybach [HL 210] motor. However, in basic principle, only our MB 507 and MB 503 motors will be proposed.”

The turret Daimler used was also discussed, with Daimler insisting on using the “OKH-Einheitsturm” (Oberkommando des Heeres Standard Turret), which reportedly Fritz Todt was in support of. It is never clarified exactly what the OKH-Einheitsturm is. Some sources seem to have assumed this meant the Panzer IV turret and associated 7.5 cm KwK 40, however this is certainly false, as from the start, the VK30 project was to use Rheinmetall’s 7.5 cm cannon. The Oberkommando des Heeres, or German Army High Command was not a designing office and would not have its name applied to anything other than for the purpose of official endorsement.

Further confounding this, the only other reference to the “Einheitsturm” is in Germany’s Panther Tank by Thomas Jentz, which indicates that it was to have been used on Krupp’s VK20.02(K) in late 1941/early 1942, mounting a “7.5 cm KwK 44”. Two 7.5 cm cannons used the designation “KwK 44”, and both came much later in the war. The first was the KwK 44 L/70, an improvement on the KwK 42 L/70 that would have been used in the Panther Ausf.F; the second was the KwK 44 L/36.5, the cannon that was mounted coaxially in the Maus. Although the latter would be the more reasonably sized given the context, neither gun is of the correct time period.

Einheitsturm may very well be the name for the turret designed by Daimler-Benz for the VK30.01(D), but the question of whether this turret design was approved by the OKH as a future standardized turret, as the name suggests, why it was chosen, how it came to be, and why no record of it exists apart from two off handed mentions, remains unanswered.

During the January 28/29th meeting, the Daimler representatives inquired as to the allowed weight of the vehicle, which Fichter told them was still 32 to 35 metric tons (even though M.A.N. had already exceeded this). Wilhelm Kissel also took this time to talk to Fritz Todt about the cooperation between M.A.N. and Daimler-Benz on their projects, which he felt was no longer beneficial. He emphasised that, “everything that is expected in meeting the design requirements derived from experience on the Eastern Front, is being met by the Daimler-Benz design.” Implying that involving M.A.N. in development was only holding Daimler back. Kissel also said that, should the Daimler design win the VK30 competition, Daimler-Benz was prepared to finish the design at their own expense. Fritz Todt agreed that the cooperation between M.A.N. and Daimler-Benz had outlived its usefulness and would allow the two firms to develop their designs separately. Following this, the February 2nd meeting between M.A.N. and Daimler was canceled.

Kissel had managed to convince Todt to allow the VK30.01(D) to go forward, and on February 2nd, Daimler’s design was finalized and deemed ready for mass production without change, much to Kniepkamp and Fichtner’s dismay. Daimler-Benz was approved to construct five prototypes, one with an MB 507 diesel engine, one with an MB 503 gasoline engine, and three with Maybach HL 210 engines. The first of these was projected to be completed in June of 1942. This is not to say that Daimler’s design had been chosen at this point, but Fritz Todt had allowed Daimler-Benz to go ahead with further development on their design without making radical changes.

The same day, February 2nd, Wilhelm Kissel wrote to Jakob Werlin (head of Daimler-Benz Munich) about his success, “Assuredly, you will greatly enjoy hearing that it was possible for me to convince the Reichsminister that a decision in favor of our new proposed tank is the correct one. When this decision is reached, the gentlemen from both the Heereswaffenamt [Wa. Prüf. 6] and M.A.N. will indeed be astonished.” A day later, M.A.N. would submit their finalized design as well. The winner of the competition would be chosen following a presentation of the two designs in Berlin on March 3rd.

On February 8th, Fritz Todt was killed in a plane crash; whatever plans he had for the VK30.01(D) went with him. However, much to Daimler-Benz’s fortune, the new Reich Minister for Armaments and Ammunition, Albert Speer, was also a proponent of their design.

On March 5th, 1942, Hitler, acting on the recommendation of Albert Speer, ordered Daimler-Benz to prepare for production of their design, giving them an order for 200 units. Hitler felt that the Daimler design was superior in almost every way, and particularly liked the fact that it used a diesel engine; he felt this was the way forward in tank design. Whether these views were entirely Hitler’s, or were seeded by Speer, is up for debate. At this time, the order for prototypes from Daimler-Benz seems to have been reduced to just two.

*These figures are rounded to the nearest fifth. They were found using the following formulae determined by the Kraftfahrt Versuchsstelle (driving test center) at Kummersdorf.
On-road fuel consumption: 8 liters per vehicle ton per 100 km
Off-road (moderate) fuel consumption: 11 liters per vehicle ton per 100 km
Calculations assumed the vehicle in question was running on 74 octane gasoline, however the Daimler-Benz design ran on diesel; meaning it would have been 15 to 20% more efficient than calculated.

Judgement

The results of the scheduled presentation of the VK30 designs in Berlin on March 3rd, 1942, have not been recorded by any available sources. Whether it occurred at all is unknown.

The scale model of the M.A.N. (left) and Daimler-Benz design (right), shown to Hitler on January 23rd. Source

As design work on the VK30 machines was finished and a winner needed to be chosen as soon as possible, Hitler had a special committee put together to weigh the advantages of both designs and suggest which should go into production. In charge of this committee was Oberst Wolfgang Thomale (OKH Inspector of the tank corps) and Robert Eberan von Eberhorst (professor at Dresden Technical University). The committee first met on May 1st, 1942, in the Bendlerblock building in Berlin, the headquarters of the OKH. Four meetings in total would be held, the subsequent three occurring on May 5th, 6th, and 7th.

Drawing No. Tu 16901 of the VK30.02(M), dated May 2nd, 1942, submitted along with M.A.N.’s proposal to the Panther Committee. Source: Germany’s Panther Tank by Thomas L. Jentz

There were two main considerations regarding which design would be selected. First was that a large number of the tank would need to be operational by the summer of 1943, and to facilitate this, production should start in December 1942. This requirement was felt to outweigh all others. The December 1942 deadline was supposedly set by Karl-Otto Saur (Albert Speer’s deputy) in a bid to win favor with Hitler by getting the new tank into production faster. The second consideration was that, in order to combat the numerical superiority of the enemy, the German machine needed to be of higher quality.

Both designs were capable of a top speed of over 55 kph (34 mph) and an on-road cruising speed of 40 kph (25 mph). Both designs carried the specified 7,5cm KwK 42 L/70 cannon with the same number of shells (79 rounds), and both designs incorporated the requested sloped 60 mm thick frontal hull armor. In fact, the armor of both tanks was nearly identical, besides differing angles of sloping the only difference was the M.A.N. design’s 40 mm (1.57 inches) of rear hull armor compared to the Daimler’s 50 mm (1.97 inch).

Comparison of the M.A.N. and Daimler-Benz designs by their stats on paper. While the Daimler-Benz design has a small advantage in armor, the M.A.N. design has a larger advantage in automotive capabilities. Table produced by Author.

Particular attention was paid to the advantages and disadvantages of transmission placement. The advantages of the forward-mounted transmission in the M.A.N. design were seen as:

  • Direct operation of the gearbox and steering (The Daimler-Benz design had to have a complicated series of linkages to allow the driver to control the transmission.)
  • The steering brakes could be adjusted from inside the vehicle
  • Less mud would be jammed up in the drive sprocket, as it would have more time to be shaken from the tracks on their return trip

Advantages of the rear-mounted transmission of the Daimler-Benz design were:

  • The heat, smell, and noise from the transmission would be as far away from the crew as possible
  • The driver and radio operator had more room
  • Space inside the fighting compartment was used more efficiently
  • The whole vehicle was lower (The hull of the Daimler-Benz design was 52 mm (2 inches) shorter than the M.A.N. design.)

Both designs would take nearly the same amount of time to construct once in production; the amount of work that would go into making one tank was projected as 1,063 man-hours for the Daimler-Benz design, and 1,078.5 for the M.A.N. design. Of these numbers, 351.5 man-hours would be required for assembly of the hull for the Daimler-Benz design, and 327 for the M.A.N. design. The M.A.N. design would require a special type of drill press to manufacture the hull.

Unfortunately, because Daimler-Benz had designed their own turret instead of using the one designed by Rheinmetall, as M.A.N. had done, they would not be able to have the turret in production by the December deadline. Additionally, the machine gun mount and optics of Daimler’s turret design were seen as vulnerable areas compared to the Rheinmetall turret. However, the final nail in the coffin for the Daimler-Benz design was the smaller turret ring. Because Daimler’s turret ring was 50 mm smaller in diameter than Rheinmetall’s, the latter turret would not fit onto the Daimler-Benz hull without significant redesign to widen the whole tank. Furthermore, the Daimler-Benz design was felt to too strongly resemble the T-34, which could lead to incidents of friendly fire. The forward-mounted turret was also seen as an issue, as the greater gun overhang increased the likelihood of impaling the gun barrel in the ground when going down hill, or catching it on trees or buildings. The M.A.N. design minimized this issue by putting the turret in the center of the vehicle. Finally, the M.A.N. design had greater operational range, provided a better firing platform on account of its suspension, used an engine that was already in production, and was more suitable for deep wading due to its sealed engine compartment. For these reasons, the “Panther Committee”, as it was known, unanimously chose the M.A.N. design.

Their decision was handed down to the chairman of the Panzerkommission, Dr. Ferdinand Porsche, on May 11th. This was also the date on which the name “Panther” was first recorded in regard to the project. The origin of the name is unknown, though Albert Speer later recalls in his book, Inside the Third Reich, that this was chosen to signify the new tank’s agility in comparison with the Tiger.

Hitler was informed of the Panther Committee’s findings in detail on the 13th of May. He felt that the rear-mounted transmission of the Daimler-Benz design was still superior, and that the 60 mm (2.36 inches) of armor on both designs was insufficient. He did concede, however, that getting the tank into production as fast as possible was the deciding factor, and that producing both tanks alongside each other would hinder this. Hitler stated that he would study the commission’s findings overnight and give his decision through his adjutant, Gerhard Engel, the next day.

Engel relayed to Porsche on the 14th that Hitler was in agreement with the committee’s findings, and that the M.A.N. design was to go ahead instead of the Daimler-Benz design. However, Hitler had stipulated that the frontal armor needed to be increased to 80 mm (3.15 inches). On May 15th, 1942, Fichtner placed a phone call to M.A.N. to inform them that they had won the contract, and of the increase in armor required by Hitler. It was also suggested that they consider Dr. Porsche’s suggestion of using a Kolben-Danek (ČKD) steering system, like the kind used in the Panzer 38(t).

Out of the Frying Pan and into the Fire

With M.A.N.’s Panther design going forward with the utmost priority, Heinrich Kniepkamp took personal charge of development. The design received the name Panzerkampfwagen V “Panther” and the Sonderkraftfahrzeug nummer (special vehicle number) Sd.Kfz.171.

On or around May 4th, one week before their design for the VK30 was chosen, M.A.N. had a final meeting regarding their design where the major details were reviewed. In addition to what has already been covered, in this meeting it was specified that:

  • There were 86 track links per side, and the width of the tracks would not prohibit transport by rail.
  • The transmission used a Maybach OLVAR 0640 12 16 gear drive.
  • The final point worth mentioning the author has been unable to determine the meaning of, other than that it relates to the transmission. “Spur gear side transmission doubly geared down, with sprockets of module 9 and 11. The middle tooth group was not required to be ground since it made no contact.”

At this point, the steering system that was to be used in the tank was undecided. It was assumed that a traditional clutch-brake steering system would be used initially. The reason for this change was that the companies that would be involved in the manufacture of the Panther did not have the proper equipment, specifically slotting machines, to cut the gears for the controlled differential type transmission. A portion of the 29 gears that made up each controlled differential were “hollow” gears, that is, the teeth were on the inside of the wheel, rather than the outside. This type of gear was significantly harder to make.

The transmission housing would be cast with steel of a strength of 60 kg/mm². Converted to megapascals, the most common unit of pressure used in describing tensile strengths, this is 588 MPa. Compare this to high strength steels, which range in the area of 750 to 850 MPa, and armor plate which goes above 900 MPa. The reason why the steel used in the transmission was so weak, relatively speaking, was to allow more units to be made. The weak drivetrain, already propelling a tank several tons heavier than it was designed for, and now made of lower quality materials, would plague the Panther throughout its service life. Any shrink holes that formed in the transmission housing from the casting process would be welded over and the whole casing would be heated and allowed to gradually cool, a toughening process known as annealation.

A conference was held on May 19th, 1942, at the Reich Ministry for Armaments and War Production. In this meeting it was determined that a majority of the facilities involved in manufacturing parts for the Panther tank would be those captured in France.

A conference with Hitler was held on June 4th, 1942, in regard to the new Panther tank. Hitler felt that by the spring of 1943, even the increased frontal armor of 80 mm (3.15 inches) would not be enough. He demanded that it be attempted to increase all frontal armor of the tank to 100 mm (3.94 inch) thickness. The same day, another meeting was held (presumably back at the Reich Ministry for Armaments and War Production, if the meeting with Hitler had not been there in the first place) between representatives of the four companies selected to build the new tank; M.A.N. of Nürnberg, Daimler-Benz of Berlin, Maschinenfabrik Niedersachsen-Hannover (M.N.H.) of Hannover, and Henschel of Kassel. It was determined that by the 12th of May, 1943, 250 Panther tanks must be available for combat. A model of the tank was displayed at the end of the meeting.

At some point during development, the L 600 C steering mechanism that was originally intended for the Panther had been dropped, in its place was the Einradienlenkgetriebe (single radius steering gear), also called the Maybach Double Differential. It is not known whether this steering mechanism is the same as the one insisted upon by M.A.N. that would allow for a pointed front hull, or if it was an entirely separate development. The Einradienlenkgetriebe is a steering mechanism completely unique to the Panther tank, having not been used on any other machine before or since. It combined two types of tank steering: the normal double differential and the controlled differential. “Single radius” refers to the fact that each gear has its own fixed turning radius (as opposed to other steering mechanisms, wherein the turning radius is variable depending on how much steering input is given). As there were seven forward gears, there were seven different turning radii, plus neutral steering.

A contract was awarded to Adler of Frankfurt am Main to deliver 50 Maybach OLVAR transmissions for testing in the Panther as an alternative to the Zahnradfabrik AK 7/200. In this configuration, the tank would have been known as Panther Model B, however the OLVAR transmissions were never installed.

In a meeting on the 13th of July, 1942, Paul Wiebicke insisted that the Einradienlenkgetriebe must be used from the start in all Panthers. When confronted with the possibility of this totally new and untested steering mechanism failing to work, he suggested that 60 clutch-brake steering systems should be built just in case, therefore they would be available to complete tanks if the Einradienlenkgetriebe turned out to not be ready.

The Panzerkommission met the next day, and again the Panther’s steering mechanism was discussed. They came to the conclusion that the first 100 tanks would have the interim clutch-brake steering system while production of the Einradienlenkgetriebe got underway. All tanks with clutch-brake steering were to be backfitted with Einradienlenkgetriebe by the end of April 1943.

M.A.N. hoped that trials of the new steering mechanism would be completed by mid-October 1942. Three different sets of gearing were put forward, the differences between them being the turning radius. The three setups would have given turning radiuses of 50, 80, and 115 meters (164, 262, and 337 feet) respectively, when in seventh gear. For speed and simplicity it was decided to only test the gearing that would give 80 and 115 meter turning radiuses. To test the two types against each other it was planned to make two interchangeable sets of gears for each of the first 20 to 30 steering units. In the final analysis, the 80 meter turning radius gearing was chosen.

M.A.N. had received a contract to complete an experimental VK30.02(M) chassis by August 1942, and a second, complete prototype by September. Both prototypes were made out of mild steel. The exact date these prototypes were finished is unknown; sources are divided as to whether the first was completed in late August or early September, but the latter seems more likely. Panther & Its Variants claims it was delivered at the end of September.

On August 3rd, Krupp, which had been in the process of designing the unrelated Panzerselbstfahrlafette IVd assault gun on the basis of their Panzerselbstfahrlafette IVc self-propelled anti-aircraft gun, was informed that the 8.8cm L/71-armed assault gun would no longer be based on its own unique chassis, but on that of the VK30.02(M), and should be redesigned accordingly. This would become what is known as the Jagdpanther.

On August 4th, M.A.N. announced that they would begin construction of the first prototype hull, and they requested that the foremen and chief operators from the Henschel, M.N.H., and Daimler-Benz plants visit M.A.N. in Nürnberg to familiarize themselves with the project.

The first prototype, VK30.02(M) Chassis Number V1, was finished without a turret. Instead, it had a box-shaped weight to simulate the turret. This machine was used for driving tests on the M.A.N. factory grounds in Nürnberg. The suspension of the V1 differed from all other Panthers in that the shock absorbers were mounted to the first and eighth roadwheel arms, as opposed to the second and sixth.


Illustration of VK30.02(M) Chassis Number V1 by Andrei Kirushkin

Due to unavailability of parts and for the sake of simplicity, the prototype was completed with a clutch-brake type steering unit. This was less efficient than the Maybach type, produced higher wear on parts, and did not allow the tank to neutral steer. Additionally, in place of the intended planetary reduction gear, this machine was fitted with a two-stage spur gear reduction of the final drive; the end result of a final drive reduction being the trade-off of speed for torque. It is unclear what steering system the V2 prototype used.

The only known photograph of the VK30.02(M) V1 undergoing trials at the M.A.N. factory grounds, seen here attempting to climb a rather impressive grade. Evidence of the vehicle’s descent into the pit, or perhaps a separate attempt at climbing out, can be seen on the far side. Source: Panther & Its Variants

The second prototype was a complete tank with turret. VK30.02(M) Chassis Number V2 mounted the 7.5 cm KwK 42 L/70 with an early, 220 mm (8.66 inch) diameter, single-baffle muzzle break in the Rheinmetall-Borsig turret. While similar to the muzzle break used by the 7.5 cm KwK 40 L/43 on the Panzer IV Ausf.F2, it was not identical. The V2 had apparently been delayed by the Rheinmetall turret not being ready in time. The turret housing was finished on September 16th, and final assembly of the turret was done at Rheinmetall’s Düsseldorf plant.

The turret used on the VK30.02(M) V2 was derived from the turret developed for the VK45.01(H2), the original Tiger tank. Back in May of 1942, it had a maximum width of 2.14 m (7 feet) which tapered to a frontal width of 1.84 m (6 feet). Excluding the cupola it was 770 mm (30.3 inches) tall. By the time the turret was built and mounted, it had grown to 790 mm tall (31.1 inches) and 2.30 m (7’7’’) wide, tapering to 2.104 m (6’11’’) wide. Increasing the height of the turret by 20 mm (0.79 inches) while also keeping the frontal plate sloped at 12° and the rear at 25°, meant that the turret also became 20 mm (0.79 inches) longer. The length would not be changed on production turrets, even when the frontal turret armor was increased to 100 mm (3.94 inches), meaning that the 20 mm of extra space needed was taken from the inside, instead of being expanded outward. Another feature of the prototype turret that would not be changed in the production model was the offsetting of the entire gun mantlet by 40 mm (1.57 inches) to the right of the centerline.

Inside view of the prototype turret mounted on the VK30.02(M) V2. The gunner’s position is to the left of the cannon and the loader’s to the right. The commander’s seat can be seen at the far left of frame. Source: Panzer Tracts 5-1

The most distinctive feature of the Versuchs-Turm (experimental turret) though, was the curved turret sides and bulge stamped into the left side of the turret to accommodate the cupola. The controls for the smoke grenade launchers were placed inside this bulge. The sides of the production turret would be widened to eliminate the cupola bulge; the layout of many of the interior components would also be changed.

View of the inside of the Versuchs-Turm from the loader’s position, facing the rear. The controls for the Nebelkerze (smoke dischargers) can be seen in the bulge under the commander’s cupola. The hatch to the left of frame is the main entrance and exit for the turret crew. Source: Panzer Tracts 5-1

When it was completed, the second prototype VK30.02(M) was sent to Kummersdorf proving grounds for official testing. The V1 was registered as IIN-2686 and the V2 as IIN-0687. “IIN” was the prefix for license plates registered to the cities of Nürnberg and Fürth. What is strange about this is that registered German military vehicles usually had a registration number with the prefix “WH” for the Heer (army) or “WL” for the Luftwaffe. Instead, the VK30.02(M) prototypes were registered as civilian vehicles in Nürnberg, the home city of M.A.N.

The hulls of the two Panther prototypes differed slightly from the production model. None of the hull plates were interlocking, as they would be on all Panthers that came after. The hull side plate did not extend past the rear plate at all. Between the 16 mm (0.63 inch) thick bottom of the hull and the 40 mm (1.57 inch) thick rear plate (reverse sloped at 30°) was a small 30 mm (1.18 inch) thick plate reverse sloped at 60°. On production vehicles this piece was eliminated, meaning the belly plate and the rear plate were directly connected to each other. The driver’s periscope was only 432.5 mm (17 inches) to the left of the centerline, on production vehicles it would be moved further out, to about 490 mm (19.3 inches) left of center line. The casting of the armored covers that went over the fans on top of the engine deck included an extension that encompassed the radiator filler cap, this would be eliminated on the production model. The drive sprockets on the prototypes were different to the production type. The dual exhausts shared a single horizontally mounted muffler, with a single exhaust pipe exiting at the center, just behind the engine deck. The roadwheels had 18 rim bolts each as opposed to 16. Finally, at the rear of the engine compartment was a single large fuel tank, the filler cap for this tank was to the left of the center line on top the engine deck.

VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the ball-shaped muzzle break, drive sprocket, and clean-cut side armor plates. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the bulge on the side of the turret which accommodates the cupola, and also the ladder on the side of the hull. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the license plate held on with wire. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the narrow rear of the Versuchs-Turm, the extensions of the armored fan covers which encompass the radiator filler ports, the single exhaust pipe, and the rear license plate hanging from the exhaust. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Source: Panther External Appearance & Design Changes
View of the engine deck of the VK30.02(M) V2 with all cover panels removed. The large single fuel tank in the rear (nearest to the camera) would be changed on the production model, with the filler port being moved to the right and the section of tank on the left being deleted. Source: Panzer Tracts 5-1

On account of the 80 mm (3.15 inch) thick frontal armor demanded by Hitler, the V2 weighed 43 metric tons – 8 tons over the 35 ton weight limit for the VK30. It was powered by a 650 hp Maybach HL 210 engine, giving it a power-to-weight ratio of just 15.1 hp/ton. This figure was 25% worse than the initial VK30.02(M) design projected. On the positive side, trials showed that there was less stress on the rubber roadwheel tires than was expected, and less stress on the torsion bars as well (16kg/mm square actual versus 20-22kg/mm square expected).

VK30.02(M) V2 on trials, likely at Kummersdorf. Source

The Panzerkommission met for the 11th time on November 2nd and 3rd, either at the 2nd Panzer Regiment’s training field in Berka an der Werra, or the nearby city of Eisenach. The following week a wide variety of experimental vehicles were to be demonstrated at Berka an der Werra — the “rough terrain” outpost of Kummersdorf — for Albert Speer and personnel of Wa. Prüf. 6. The vehicles slated to be present at the demonstration included VK30.02(M) V2, VK30.01(D), a VK36.01(H), a Panzer II with a Zahnradfabrik Electric Transmission, a Panzer III with Ostketten, a Zugführerwagen 40 (Panzer III with Schachtellaufwerk overlapping suspension), the Zugführerwagen 41 (Panzer III with rubber-saving roadwheels), two Henschel Tigers, one with a Zahnradfabrik 12E-170 Electric Transmission, two Porsche Tigers, two Panzer IIIs and two armored cars with with flamethrower equipment, a T-34, and a KV-1. A number of half-tracks, trucks, and tractors were also involved in the display, namely four Sd.Kfz.3s, an Sd.Kfz.10, an Sd.Kfz.11, two Radschlepper Ost, a Raupenschlepper Ost, a French Latil, and an Opel Blitz 3,6-6700 A.

The supposed presence of a VK30.01(D) at this demonstration is the only evidence for a Daimler-Benz Panther ever being built to a degree where it would be operable. Sadly, there are no known photographs of the vehicle selection at this demonstration which would confirm many details about the lost history of the VK30.01(D).

On the first day of demonstrations, Albert Speer drove the VK30.02(M) V2 for one and a half hours. He was highly complimentary of the tank’s handling. The trials showed that the differential worked well in rough terrain and that the tank turned fine without having to rely on brake steering. At this time, the V2 was temporarily equipped with a controlled differential discontinuous regenerative steering unit. This would not be the same as the Einradienlenkgetriebe, and may in fact be the L 600 C. The delegation from M.A.N. present at the demonstration stated they were satisfied with the performance of their prototype.

On the 4th of December, the first Einradienlenkgetriebe delivered by Henschel was installed in the VK30.02(M) V1. The performance of this vehicle with the new steering mechanism was not recorded. This was the last use of the VK30.02(M) as a developmental platform, as the Panzerkampfwagen V went into production in January 1943.

Daimler’s Requiem

Information regarding the development and construction of the Daimler-Benz design is frustratingly slim. Only bits and pieces exist that, when cobbled together, give a rough idea of the sequence of events following Daimler’s loss of the Panther contract. Unfortunately, many of Daimler-Benz’s files were destroyed at the end of the war, and much of what did survive fell into possession of the Soviets. While the Iron Curtain has now fallen, this information has still not escaped the Russian archives.

Following M.A.N.’s victory in the VK30 program, Albert Speer informed Daimler-Benz on the 20th of May that work on their design was to cease. However, they would be allowed to complete the two prototype machines that were already under construction. With M.A.N.’s design selected after all, the previous order for 200 Daimler-Benz tanks was withdrawn.

The loss of the VK30 contract was discussed by the Daimler-Benz board of directors on June 3rd, 1942. The following transcript of that meeting is from Germany’s Panther Tank by Thomas Jentz.
“Our proposal for the new tank was not accepted by the special commission established by Hitler. Instead they selected the M.A.N. design for large scale production, after the initial proposal from M.A.N. apparently was improved. During a meeting, M.A.N. had the opportunity to learn all the advantages of our proposal which they then took into consideration in their own design.
At first, the majority of the experts were impressed by our proposal. Even Hitler expressed his approval. But then, the commission consisting of Thomale and Eberan, decided against us for the following reasons:

  • The double torsion bar suspension from Porsche was chosen over our proposed leaf springs.
  • The MB 507 motor proposed by us can not be produced in the number required.
  • Our design requires a new turret. The turret for the M.A.N. design was already designed. The M.A.N. vehicle had front drive, our vehicle rear drive. Because of the rear drive our vehicle required a new turret design. It was admitted that the rear drive possessed advantages.

We are completing only two experimental vehicles, that positively will make a good impression. The two experimental vehicles are to be completed in June/July 1943. The entire tank should be completed since we can finally obtain the turret ourselves. We still have the contract to build these two prototypes and therefore we also want to demonstrate these as completed tanks.”

The same month, June 1942, the MB 507 diesel engine was installed in the first prototype. It is believed the first VK30.01(D) was completed about September, likely excluding any sort of turret. As was discussed in the previous section, it is reported that the Daimler-Benz Panther was present at Berka an der Werra in November of 1942, and that it competed alongside the VK30.02(M) prototype.

The fact that an operational VK30.01(D) existed no later than November is an apparent contradiction to Daimler’s own estimate of June or July 1943 as the completion date. It is possible this was the projected date for total completion of both the first and second prototypes, including turrets, which needed to be made from scratch.

If the VK30.01(D) prototype was in fact made to run at some point in 1942, then the question remains, why are there no photographs of it? While photographs of the VK30.02(M) prototypes are few in number, enough exist to give us a visual history of the vehicles. Only two photos remain of a VK30.01(D) prototype, both show it in an incomplete state without a turret and running gear, left outside the Daimler-Benz plant in Berlin at the end of the war.

A still image from a video survey taken by the western Allies of the Daimler-Benz Marienfelde plant after the end of the war. The unfinished VK30.01(D) hull is seen among other discarded weapons and vehicles. It is painted in RAL 3009 Oxidrot (oxide red) primer. The vehicle to the right of frame is the VK20.01(D), the earliest ancestor of the Daimler-Benz Panther. The field gun beside the VK30.01(D) is an 8cm Panzerwurfkanone 8H63, previously known as the PAW 600. To the left of the VK30.01(D) is the hull of a StuG III Ausf.G with the Saukopf gun mantlet. Source: Unknown

The quality of these photographs is poor, but with digital manipulation, more details can be brought out that show this hull is quite different to the original VK30.01(D) design. The most prominent feature is the presence of return rollers mounted on top of the leaf spring bundles. This has been the most vexing question raised during the writing of this article, and one which no credible source dares to expand on. While the interpretation regarding the January 28/29th meeting that the phrase “long suspension” is in fact talking about the length of suspension travel and not the length of the track in contact with the ground is very much grasping at straws, there is no other explanation for the change in suspension layout that is not based entirely in conjecture and even fiction.

In addition to the suspension, mudguards, and the slightly redesigned driver’s visor, which placed the periscope further forward than that of the mockups, other features seen only on this hull include an amorphous bulge on either side of the lower hull, just rearward of where the idler wheel would be, and a black-colored triangular extension of the hull atop the left side mudguard. The purpose of these features is not known; the only potential clue to their use is one of the only known blueprints for the VK30.01(D), which shows a linkage of the track tensioning system protruding up through the frontal glacis of the hull in the same area as the box

VK30.01(D) blueprint, notice the black linkage coming from the idler wheel at the front of the hull. Source
A lightened and cropped version of the first picture, showing the first of three return rollers and the bulge on the left side of the hull. Source
Photograph taken of the same hull from the other side. This angle more clearly shows the undocumented features of this hull, namely the box atop the left side fender, the front mudflaps, modified driver’s port, and suspension with return rollers. Also of note are the Panther tracks in the foreground; it is not known whether these were to be used on this prototype, or if it is merely a coincidence they are here. The hull of the vehicle to the left of frame seems to be that of another VK20.01(D). Source: Panther & Its Variants
An enhanced version of the previous photo. The three return rollers and unfinished suspension are easier to see.
Another still taken from the same film as the first photograph of the VK30.01(D) hull. The framework on the building on the right matches that seen in the first still. At the extreme right of frame is what appears to be the front right corner of the VK30.01(D) hull poking above a pile of rubble between it and the camera. Note at the extreme left of frame is the hull of an Sd.Kfz.8 Typ DB 10 half-track. Source
Overview of the bombed out Daimler-Benz Marienfelde plant taken from across the street. This photo seems to be from a later date as some of the rubble has been cleared and the scaffolding on the main building has been removed. Arrows have been drawn on the enlarged portion of the photo to show the Sd.Kfz.8 hull and what may be the VK30.01(D) or the VK20.01(III). Source: Daimler AG “Mercedes-Benz Classic”

The history of the Daimler-Benz Panther between November 1942 and June 1945 has been lost to time. While there is no direct evidence that the second prototype, which would have mounted the MB 503 gasoline engine, was ever completed, or even laid down, there is circumstantial evidence to suggest this may be the case. Daimler-Benz’s official production numbers for Panther vehicles is 545 for 1943, and 1,215 for 1944. These figures are including all vehicle types in the Panther family, for instance the 1,215 figure is a summation of the 1,175 Panthers and 40 Bergepanthers that Daimler-Benz produced in 1944. Daimler’s figures are perfectly in line with the actual production numbers confirmed by the author, with the exception that Daimler-Benz produced only 543 Panthers in 1943. This leaves 2 vehicles unaccounted for; the same number of VK30.01(D) prototypes Daimler intended to make.

Without knowing for certain when and how the change in suspension came about, it can not be taken for granted that the vehicle seen in the photos is the first prototype. Its incomplete state would indicate that some work had gone into the VK30.01(D) after the November demonstration in which the first prototype took part, whether this was construction of a second prototype or deconstruction of the first. The final fate of the Daimler-Benz Panther remains unknown.


Conservative reconstruction of the incomplete VK30.01(D) hull found at the Daimler-Benz factory in 1945 based off of photographs and supplemented with known features of the original design. The hull with return rollers is seen in photos to have the same mounting brackets for leafsprings as the original hull design, thusly it is drawn here with leafsprings.


Hypothetical reconstruction of the incomplete VK30.01(D) hull with return rollers, closely following the original design which lacked them. The retention of the same leafsping suspension suggests relatively unchanged running gear, merely lengthened to accommodate the return rollers, hence the author’s “long suspension” theory. Certainly this arrangement looks quite attractive, and would have greatly improved the VK30.01(D)’s vertical stepping ability — an area where it was outclassed by the VK30.02(M). All illustrations on this page by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

Final Disposition of the Prototypes

With the Panzerkampfwagen V Panther in production, the two VK30.02(M) prototypes had served their purpose. What became of the VK30.02(M) V2 is not known, as there is no record of it past December 1942. The V1 prototype, on the other hand, did go on to serve a useful purpose as a suspension testbed. No written sources detail the post-1942 career of the VK30.02(M) V1, photographs are all that is left to tell the story.

Sometime in 1943 or 1944, the VK30.02(M) V1 was modified to replace its 18 bolt roadwheels with new Gummisparenden Laufwerke (rubber-saving running gear), all-steel roadwheels. These 800 mm (31.5 inch) diameter roadwheels were designed to save precious rubber, a resource that Germany was quickly running out of; they were to be used on both the Panther II and Tiger II, and eventually would also be used on the Tiger Ausf.E and Panther Ausf.G. The VK30.02(M) V1 was also fitted with Transportketten (transport tracks) and new drive sprockets and idler wheels. Transportketten were 660 mm (26 inch) wide tracks used on the Tiger and Tiger II to allow those vehicles to fit on railcars; these tracks were intended to be used as the main combat tracks for the Panther II, which was under development in 1943, aimed to replace the troubled Panther Ausf.D and standardize components with the Tiger II, then also under development. The drive and idler wheels used on the VK30.02(M) V1 test vehicle seem to be completely unique, they do not resemble those used on the Panther II or any other tank.

Without supporting documentation as to when this conversion was made, it is impossible to say for certain its purpose; however, the fact it is equipped with Gummisparenden Laufwerke and Transportketten, both features of the Panther II, would suggest that this was a testbed for that vehicle. This is contradicted by the fact that the only known photos of the VK30.02(M) V1 in this configuration come from 1944, a year after the Panther II was cancelled.

During a series of tests in 1944 at the M.A.N. plant, the VK30.02(M) V1 Testbed was fitted with a vibration measuring apparatus. This consisted of a bicycle wheel “idler” in contact with the ground, a vertical track for the idler to move up and down on so to stay in contact with the ground, a lever which reduced the input from the idler by 2:1, and a further 6:1 reduction device in conjunction with a vibration recorder. Several wires ran from the sensor to the inside of the tank, presumably to a recording device.

The VK30.02(M) V1 Testbed driving over a wave road in 1944. The single bicycle tire on a vertical track mounted to the side of the tank is a system for measuring vibration. Source: Panzer Tracts 5-1
Another shot of the above. The license plate seems to have fallen off between this shot and the previous one and has been stuck back on sideways. On the left mudguard appears to be a Wolfsangel, a rune emblematic of the 2nd SS Panzer Division; the purpose of its presence is not known. Source
Closeup view of the vibration measuring device. Source
What may possibly be a photo of the VK30.02(M) V1. Other Panther chassis used for developmental purposes were also fitted with the same type of turret-simulating test weight, but usually without the observation cupola. The fact that this tank has two headlights and an apparent foot step on the side of the test weight are in line with the VK30.02(M) V1, but without greater detail it cannot be said for certain. Source

Allied reports on the post-war evaluation of Henschel’s Tank Proving Ground in Haustenbeck mention what may be one of the VK30.02(M) prototypes. Apart from the incomplete E-100 and Grille 17, two Tiger IIs, a Jagdtiger, a Panther Ausf.G, and two VK30.01(H)s also found at Haustenbeck, it is recorded that, “Two tanks made during early German tank development are also in this area. They are of light armor plate and show distinct lines of the Mark IV and Mark V tanks. The salient feature is in the development phase of their suspension systems.” Unfortunately, photos of these tanks have not been found.

Sources

AFV Profile 10 Panzerkampfwagen V Panther – Chris Ellis and Peter Chamberlain, ~1972
Armor at War Series Panther cn7006 – Thomas Anderson and Vincent Wai, 1996
Germany’s Panther Tank: The Quest for Combat Supremacy – Thomas L. Jentz, 1995
Osprey Military Fighting Armor of WWII Panther Variants 1942-1945 – Hilary Doyle and Thomas Jentz, 1997
Osprey New Vanguard Panther Medium Tank 1942-45 – Stephen A. Hart, 2003
Panther vs T-34 Ukraine 1943 – Robert Forczyk, 2007
Panther & Its Variants – Walter J. Spielberger, 1993
Panzer Tracts No.5-1 – Thomas L. Jentz and Hilary Louis Doyle, 2003
Panther External Appearance & Design Changes – Roddy MacDougall and Martin Block, 2016
Inside the Third Reich – Albert Speer, 1969
https://warspot.ru/14561-panteri-predki
http://www.gizmology.net/tracked.htm
ETO Ordnance Technical Intelligence Report 288 – Henschel Tank Proving Ground, 24 May 1945
100 Jahre DaimlerChrysler Werk Berlin – Chronik 1902 – 2002
Correspondence between the author and staff of Daimler AG
Correspondence between the author and staff of Rheinmetall AG

The author would like to express the utmost gratitude to the staff of Daimler/Mercedes for their generous assistance in providing information.

Categories
Cold War American Other Vehicles

Crawler-Crusher, or “The Monster”

USA (1968-1969)
Civil Engineering Vehicle – 1 built

Background – The Cross Florida Barge Canal: “The Ditch of Dreams”

As far back as 1565 with Governor Pedro Menéndez de Avilés, when Florida was ruled by Spain, people have dreamed of cutting a waterway across it to shorten the voyage to the Gulf of Mexico from the east coast of America and from Europe. United States territorial governments in Florida first started considering a canal in the 1820s, with the first legislation being the Canal Memorial sent to Congress in 1825. Andrew Jackson (President of the United States, 1829-1837) had supported the idea of a canal during his tenure as Governor of Florida in 1821, but he did not condone the use of taxpayers’ money for the project as President, and the project was rejected as unfeasible.

The next attempt to build a canal across the width of Florida after the failed 1820 motion, was during the Great Depression. Calvin Coolidge’s River and Harbor Act of 1927, which ordered the US Army Corps of Engineers to carry out surveys, the cost of which had been determined two years prior, would form the basis for the project which would see the first breaking of ground on a cross-Florida canal. After extensive lobbying and political squabbling, in 1935, President Franklin D. Roosevelt approved the use of 5 million dollars to construct the Atlantic-Gulf Ship Canal, which would provide jobs as part of his New Deal program.

Route 13B was chosen as the path for the canal. It would run from Palatka to Yankeetown via the St. Johns, Ocklawaha, and Withlacoochee rivers. The St. Johns River, and to a lesser extent, the Ocklawaha River, had been important transport and trade routes for much of Florida’s history. The St. Johns is a wide river providing access from the Atlantic Ocean to the cities of Jacksonville and Palatka. The Ocklawaha River is a much smaller, winding tributary of the St. Johns, which feeds into the latter just north of Lake George. The Ocklawaha meanders its way further inland before turning South and continuing all the way to Lake Griffin, near Leesburg. Before railways were built, the Ocklawaha had been the route connecting Lake Apopka with Jacksonville and the ocean. The Withlacoochee is on the other side of Florida; emptying into the Gulf of Mexico near Yankeetown. It runs inland and then south to Green Swamp. Green Swamp also happens to feed the Ocklawaha, though indirectly. Had the canal been finished, the two halves would have come together south of Ocala, Florida.


Map of the would-have-been Cross Florida Barge Canal, made in January 1971 Source

Construction began in 1935. The canal was to be a sea level canal, meaning it would cut straight through any mountains or hills along its path, and would not require any locks to change ships’ elevation. Due to political opposition from Secretary of the Interior Harold Ickes, who claimed that a sea level canal would destroy Florida’s aquifers, work on the canal was cancelled within a year. Other political factors also contributed to the cancellation of the Atlantic-Gulf Ship Canal, such as a need for disaster relief elsewhere in Florida, and pressure from the railroads and the city of Miami. The Depression Era canal attempt ended with only a few miles of ditches dug, some abandoned structures, and $5.4 million in wasted federal appropriations.

The cross-Florida canal idea was revisited in 1942 as World War II was in full swing and thousands of tons of shipping were being lost to German U-boats off the coast of Florida. The canal was proposed as a means for ships to avoid the U-boat infested waters of the Atlantic when making trips from the US East Coast to the Gulf of Mexico. Construction of the canal was approved as a wartime defense measure, however, Congress was still divided on it, ending in a tie that was only settled in favor of the canal by Vice President Henry Wallace. Despite being approved, the canal was never funded; unsurprising considering the mixed response from Congress in the first place. Political pressure also influenced this decision, as there was concern that had a canal been built it would rob port traffic from Palm Beach, Fort Lauderdale, and Miami. However, the men who served in World War II, and saw the loss of life at the hands of the U-boats first hand, would remember the government’s indifference to what they saw as a life-saving measure. Some of them would go into politics and would ascertain the third and final attempt at a canal in the 1960s.

Approved in 1963 by President John F. Kennedy, work started in 1964 under President Lyndon B. Johnson, the Cross Florida Barge Canal project was born out of a political struggle much too in depth to cover here. The project would run from 1964 to 1971 and follow much the same route that the 1930s canal would have. It was intended that the canal would benefit central Florida militarily, economically, and recreationally. The US Army Corps of Engineers was put in charge of construction of the canal and broke ground in February, 1964.

Only two locks, Buckman and Inglis, were completed on the Cross Florida Barge Canal, with a third, Eureka, left unfinished. The first lock built was originally known as the St. Johns Lock, but was renamed Henry H. Buckman Lock, or simply Buckman Lock. Buckman Lock is the closest lock on the canal to the St. Johns River. It sits on a man-made portion of the canal connecting Rodman Reservoir and the St. Johns, bypassing the lower Ocklawaha. Buckman Lock is less than two miles (about 3 kilometers) from the St. Johns River and 4.75 miles (7.64 km) from Rodman Reservoir. Construction began in 1964 and was completed in 1968. Buckman Lock is the lock for Rodman Reservoir, despite being some distance away from it.

Work on Rodman Dam and Eureka Lock and Dam began about the same time in 1966. Rodman Dam is roughly 7 miles (11.25 km) from the St. Johns River. Eureka Lock and Dam, named for the nearby town of Eureka, is 21 miles (33.8 km) upstream from Rodman Dam. Eureka Lock and Dam was entirely complete apart from a 400 foot (122 meter) section of the 4,000 foot (1,220 meter) wide earthen dam that was never filled in.

Work on Rodman Dam and Reservoir was conducted by the Army Corps of Engineers from 1966 until September 30th, 1968, when the dam was closed and the reservoir filled. Rodman Dam is about 7,200 feet (2,200 m) long, 300 feet (91 m) wide at the base, and 30 feet (9 m) wide at the top. It has a four gate spillway, each gate measuring approximately 40 feet (12.2 m) wide by 15 feet (4.6 m) tall. The gates can be lifted above the spillway to increase flow. The top of the dam is 28 feet (8.5 m) above sea level and 22 feet (6.7 m) above the surrounding natural ground elevation. The spillway crest is only 6 feet (1.8 m) above sea level. The spillway’s ‘apron’ (the flat, sloping, concrete path where the water leaving the spillway flows) is 100 feet (30.5 m) long, about 160 feet wide (48.8 m), and ranges in elevation from 3 to 15 feet (0.9 to 4.6 m) below sea level. The spillway discharge channel is nearly a mile long, has a depth of between 8 and 20 feet (2.4 to 6.1 m) depending on flow, and narrows from about 300 feet (91 m) to about 150 feet (46 m) before meeting what remains of the Ocklawaha River. The Ocklawaha meanders for another 11.6 miles (18.7 km) and then empties into the St. Johns south of the canal exit.

The only other completed lock is on the Gulf coast of Florida, near Yankeetown. The Inglis Lock and Dam is located on the Withlacoochee River, and holds back Lake Rousseau. Inglis Lock is the only portion of the Cross Florida Barge Canal to have seen use besides Rodman Reservoir. The lock has since fallen into disrepair and has not operated since 1999.

In total, the Cross Florida Barge Canal would have been 107 miles (172 km) long when completed. However, construction work was slow, and quickly fell behind schedule, probably not least in part due to lack of unified enthusiasm for the canal and public backlash. In an age when environmentalism was on the rise, seeing ancient forests destroyed and thousands of species of plants and animals threatened to make way for “more recreational waters” and a barge canal that was not really needed angered and divided the population. Marjorie Harris Carr, for whom the greenway that now spans the would-be area of the canal is named, led the public protest efforts against the canal for much of the losing battle. In the end, however, public outcry was too much to ignore, which led President Richard Nixon to sign an executive order to halt construction of the canal on January 19th, 1971.

The Monster from Fern Gully

Part of creating the aforementioned dams and the artificial reservoirs that would be held behind them was clearing the area of trees and other ground clutter. The goal was to have a central channel through the reservoir, of sufficient depth (12 feet / 3.65 m) to accomodate barge traffic. The area the channel would be cutting through on the Rodman and Eureka Reservoirs would be the general path once run by the flowing Ocklawaha. Area around the channel, which would soon be underwater if it wasn’t already marshland, would also need to be cleared to prevent underwater obstacles being swept into the barge lane, and to keep the area open for recreational pleasure craft. The task of clearing the swamp that occupied the area that was slated to become the Rodman Reservoir was especially daunting, in some places the swamp water was up to 6 feet (1.83 m) deep.

With this in mind, the Army Corps of Engineers asked for bids from civilian firms to do the clearing work. The barge channel was to be 400 feet (122 m) wide and 16.5 miles (26.55 km) long in Rodman Reservoir alone. 5,617 acres of land were to be cleared, 708 acres of that figure representing just the channel. The heavily forested section of Rodman Reservoir comprised 6,325 acres of ancient swamp forest. The time allotted for clearing the reservoir was a mere 445 days.

F. Browne Gregg, head of the company Gregg Gibson & Gregg, put in a very low bid; far too low in hindsight. With a bid 1 million dollars less than the next lowest bidder, Browne Gregg easily won the contract from the Army and was awarded $4,191,047. Soon though it was abundantly clear that doing the work traditionally of felling and removing thousands of acres of swamp and forest on the budget that the bid had given them would run the company a major loss. To get around this, Gregg came up with a novel solution; he would build a massive tracked vehicle, capable of going on land or water, that could be filled with water to increase its weight. The vehicle would weigh so much, and be so large, that with its sheer bulk it could push over trees up to 6 feet (1.83 m) in diameter, drive over them, stripping them of their branches and crushing the trunk and branches into the mud, where they would remain. Gregg hoped that this machine would save over a million dollars in clearing costs. The Crawler-Crusher was designed in only a few hours and perfected over only one weekend. It was designed to clear swamp at a speed of only half a mile per hour (0.8 kph), slightly slower for clearing dry land.

“I literally woke up from a sound sleep with ideas running through my head. I wasn’t thinking in words in my sleep but in moving pictures of machines and how I would utilize the equipment. I got up and went to the kitchen to brew myself a pot of coffee. By the time I had a hot mug in my hand, I knew what my first sketch would be. I had a draft board with a target light set up in my bedroom and I went to work.

I stayed at it, working on what I called the Crawler Crusher night and day. I was obsessed by the thing. I was oblivious to [my friend] Fred and his pal Jeff Cherry coming in and out of the bedroom. Jeff kept asking me, “What’s that you’re drawing, Mr. Gregg?” I ignored him as I was concentrating. He looked over my shoulder and watched what I was doing. He spoke right up and said, “Mr. Gregg, you forgot to put the hole on the top for the man to crawl into.” He was right and I told him I would get to it later. And sure enough, a few hours later, the boys were back, checking up on me. To them it was just a nifty army tank I was drawing for our military.”
-F. Browne Gregg on designing the Crawler-Crusher, taken from his autobiography Progress Through Innovation.

US Patent 3418961A, plainly entitled “Swamp Clearing Machine”, was filed by Frederick Browne Gregg of Leesburg, Florida, on behalf of Gregg Gibson & Gregg, Inc. on March 17th, 1967 and issued on December 31st, 1968, the machine itself having been completed at least several months prior. The dates surrounding its construction and operation are not known.

Crawler-Crusher patent Figures 2 and 4 respectively, showing the right side and right side cutaway of the machine. Source

In summary, the Crawler-Crusher is described by the patent as follows:
“It is a very large machine consisting of two large, hollow, watertight track pods. These pods can be separated for transport, and contain pumps that facilitate filling and draining them of water to control the weight of the vehicle. The design builds upon the armored, amphibious tree clearing machines in use by the US Army in Vietnam at the time. The Crawler-Crusher is superior to the Army’s tree clearers because it is fully amphibious and can regulate its ballast. While the Army’s tree clearers are at home on hard ground, sand, or open water, they struggle to operate in mud and marsh, where they bog down and cannot gain sufficient traction.”

The Crusher’s left and right track pods were mirror images of each other, but otherwise were identical. Each pod by itself measured roughly 50 feet (15.2 m) long, 12 feet (3.65 m) wide, and 12 feet 6 inches (3.8 m) high. Including the operator’s cabin, the entire machine stood 22 feet (6.7 m) high. For comparison, the largest tracked tank ever built (albeit unfinished), the K-wagen, measured 42 feet 8 inches (13 m) long and 19 feet 8 inches (6 m) wide.

Structurally, the Crawler-Crusher’s track pods were constructed and reinforced with hundreds of I-beams. Sixteen I-beams were oriented widthwise along the bottom of the pod, above the area containing the track rollers and their supports. The I-beams near the front and rear of the pod were tilted to follow the curvature of the bottom of the pod. There were two rows of short, vertical beams running down the center of the bottom of the pod between the two track roller channels, these supported the above mentioned 16 I-beams.

Above each of the 16 horizontal I-beams were 4 beams arranged diagonally which resembled a “W” shape when viewed as a cutaway from the front. The outermost arms of the “W” were placed in front, with the inner arms following immediately afterward. Each of these cross-beams was half the width of the I-beam they rested on, meaning they were all fully supported. In the center of each “W”, of which there were 16, one for each supporting I-beam, was another, shorter, vertical beam that separated the “W” in half. There were also occasional vertical I-beams placed directly against the inner and outer walls of the track pod, on either end of the “W”s; it is unclear from the blueprints whether these were continuous down the entire length of the track pod, if there were 16 of them and they were attached to the “W” frames, or if there was only a couple that were placed in specific areas.


Crawler-Crusher patent Figure 3, showing the vehicle from the front, the right side pod cutaway back to the partition wall midway down the length of the vehicle. Source

The four beams of the “W”, the central vertical beam, and the side vertical beams all supported a framework inside the pod that formed a floor, or “inner deck”. The height of the inner deck was at approximately 40% of the pod’s total height. Above the inner deck, extending to the roof, were over 100 vertical I-beam supports. There were 18 or 19 rows lengthwise down the pod, each row consisting of 7 beams widthwise. The outermost two beams in each row were placed directly against the outer and inner walls respectively. At the top of the pod, supported by the aforementioned vertical beams, was another framework of I-beams that support the roof and return rollers.

Entrance to the pod was via a side hatch, which was watertight and could be locked with two dogs (small, solid pieces of metal that are hinged on one side and can be flipped out to secure the door). The side entrance doors were hinged on the side facing the rear of the vehicle and opened outwardly. The entrance hatches were between rows 10 and 11 of the vertical I-beams (counting from the front). Directly across from the two exterior doors, on the inner walls of the pods, were two more doors. These allow travel and communication between the two pods when the machine is assembled. The inner doors were virtually identical to the outer doors, also being watertight and having locking dogs, but they are presumed to open inwardly. When the right side inner door is viewed from the inside, the hinges were on the right; the left side inner door is not illustrated or seen in any photos. The inner deck was partitioned off at beam row 10, dividing the interior of the pod into two large sections. Access to the forward compartment was via another hatch, identical to the side access hatch; it was placed between beam columns 3 and 4 (counting from outboard to inboard). For the right side pod, this hatch was hinged on the side facing outboard; again, the hatch in the left side pod is not seen in the blueprints.

Entrenched in the bottom of each pod were two channels containing the support rollers for the track. There were 188 rollers in total; the rollers themselves were the type normally used on Caterpillar D8 bulldozers. Each roller axle was supported by a pillow block bearing on either side, meaning there was no suspension at all. The roller itself was a cylinder with an enlarged band in the middle and flanged ends, this arrangement created two channels on the roller in which the track’s guide horns rested.

The return rollers on the top of the machine were nearly identical in construction to the support rollers, except for the fact that their ends had smaller flairs, and that the channels they rested in were not continuous along the entire vehicle. Each return roller had its own “well”, a recessed area it rested in. Each return roller well had a drain plug at the bottom underneath the roller, to let out rainwater. There were 4 top return rollers per channel, meaning 8 per pod, and 16 in total. At the back of the pod, above a small slanted rear roof section, were 2 more return rollers per channel, meaning 4 per pod, and 8 total. In total there were 12 return rollers on each track pod; 41 support rollers for each channel, 82 on each pod, and 164 total. For comparison, the TOG II* tank, known for its size and length, had only 32 support rollers in total.

The track links themselves were 11½ feet wide (3.5 m) and were made from a special steel alloy used by Caterpillar. Each track had a grouser of approximately 5 inches (127 mm) long, tapering from approximately 2.5 inches (63.5 mm) to 1.5 inches (38.1 mm) in girth. These long grousers gave the Crawler-Crusher a means of propulsion in the water, acting like paddle wheels. “Skids or wear strips” were placed along the bottom of the pod near the ends of the track links to support the outer length of the track and prevent them from bending and warping under the machine’s weight.

Propulsion for each track pod was provided by a Caterpillar D432 diesel engine, taken out of a Cat D8H bulldozer. Each engine produced 270 horsepower at the flywheel, for a total of 540 (FW) hp. Each engine, mounted on a support beam above the inner deck of its respective pod, drove a driveshaft that went through the rear wall of the pod, into a differential that took up the entirety of the rear of the pod beyond the rear wall. On either side of the differential was a large drive sprocket. The clutch for the differential was pinned in place, as it was only driving one large track instead of two smaller ones, and moving one sprocket more quickly than the other would be catastrophic. The patent remarks that even though the machine being built is powered by internal combustion, the design could accommodate any means of heavy-duty propulsion, such as hydraulic or electric drives.

At the front end of the vehicle, the toothed idler wheels were supported on sliding members that were mounted on top of support beams that jutted out through the front wall of the pod. The idler wheels were each connected to a tensioning piston that was connected to a double-acting cylinder, mounted on the same support beam but on the interior of the pod. This support beam was held strongly in place and continued all the way back to beam row 4.

Each track pod weighed approximately 200,000 pounds (90,700 kg) and could be increased by 100,000 additional pounds (45,400 kg) by filling the area below the inner deck with water. An inlet pipe was mounted directly on top the inner deck between beam rows 12 and 13; it carried water from a small, screened opening on the side of the pod to near the middle of the pod, where it made a 90° turn downward, dumping through the roof of the lower compartment. A solenoid valve was mounted along the pipe immediately after it entered the pod from the outside, this could be controlled by the operator of the machine remotely to start or stop filling the ballast.

A 4 inch (101.6 mm) ballast pump was mounted atop the inner deck next to the front of each of the engines. The pump was driven by a belt from the engine; itself driving a shaft that went to an impeller on the end facing the front of the pod. The patent again remarks the pump can be hydraulic, electric, or even a separate combustion engine if desired. A header pipe came out the front of the impeller housing and made an immediate 90° turn downward through the deck. The header pipe met a cross-joint at the same level as the I-beams that lay widthwise across the roller channels. The cross-joint split the pipe into three separate pipes, one continued straight down, while the other two traveled out to the sides of the pod before making 90° downward turns. All three of these sump intakes were held at only about an inch or two (~25 to 50 mm) above the bottom of the pod. Attached radially to the top of the impeller shroud, the outlet pipe went directly out to the side of the pod, passing through a one-way valve before going out the side wall behind and above the inlet pipe. The sump tubing was contained between beam rows 13 and 14.


Crawler-Crusher patent Figure 5, showing the right side pod cutaway back to the sump, just in front of the engine. Source

A feature outlined in the patent that does not seem to have been used on the actual machine is the vent line. Mounted on the inner wall, just behind beam row 9, the vent line seems to have been a safety feature of dubious necessity, perhaps for if the ballast tank became overfull, or somehow became pressurized. The vent line would be opened and closed by a wheel valve mounted at about chest height. It continued from below the inner deck, up and out through the top of the pod, rising to just under the bottom of the control cab, before making a quick 180° curl outward, to prevent rain from getting in. An optional auxiliary vent line could be built off the main one, extending from under the wheel valve, back through the partition wall at beam row 10, making a 90° turn downward and going through the floor. The auxiliary vent line could have a blow off valve mounted on top of it, underneath the wheel valve on the main vent line, should it be so desired.

The track pods were attached together by multiple sets of splined recesses, or sockets, that were inlaid into the inner walls of each pod. A splined shaft is fitted between each of these sets of sockets so that they line up, and then can be pushed together. (This is very similar to how Lego axles, or “stick” pieces are attached together). A heavy duty bolt is fed through the end of one socket, through the middle of the joining piece, and out the other socket, where it is secured by a nut.

When fitted together, the two-track pods form two vertical sockets between them which the 8 inch (203 mm) thick support posts for the operator’s cabin fit into. The two support posts were cross-braced to each other; the overhanging portion of the cabin was supported on the four corners by diagonal supports coming off the support posts. In the patent, the cabin is shown as a simple box, the bottom half of which is solid (presumably wood or metal) and the top half wire mesh, with a flat roof. The real machine had a cabin of less crude construction, with glass replacing the wire mesh, and a tall, curved roof.

Behind the sockets for the cabin supports, each track pod also had a long, shallow recess that when fitted together created a vertical “letter slot” extending from behind the cabin nearly to the end of the vehicle. This slot was divided with vertical separators into a forward section, a small middle section, and a rear section. The front section was connected to ductwork running along the roof of the right side track pod, providing air to the engine. The rear section of the open-air slot likewise, but providing air to the left side engine. Both engines exhausted into the center section.



Crawler-Crusher patent Figures 1 and 6. Figure 1 shows the entire vehicle as seen from above. Figure 6 shows the rear half, with the engine compartments, final drives, air intake ducts, and exhausts outlined. Figures 7 and 8 show the method of attaching the two track pods together by splined sockets and shaft, and Figure 9 shows a side view of several track links. Source

At the front of the vehicle, there was a large pusher-bar for pushing over trees. The concrete-filled pusher bar extended 5 feet (1.5 m) forward of the vehicle, and towered approximately 15 feet (4.57 m) off the ground. The pusher bar was supported by two A-frames, one on either side of the machine. The top leg of each A-frame was connected by a pin to a support bracket on the top corner of the respective track pod. The bottom leg of the A-frame was also connected to a bracket by a pin, the bracket being supported by a structural beam coming off of the lower side of the track pod. Diagonal struts reinforced the corners of the pusher bar. The patent mentions the possibility of making the top A-frame brackets into pivots and replacing the bottom ones with hydraulic pistons to raise or lower the pusher bar, but this seems highly unnecessary.

The difficulty of transporting 50 foot (15.24 m) long, 12 foot (3.66 m) wide track pods, as well as the machine’s other accessories is quickly glossed over in the patent. It is claimed the track pods, when separated, can be moved to or from a job site by barge, railway flat car, flatbed truck, “or any other known manner”; however, while the length of the apparatus will fit on a railcar or semi-truck, the width would be a major problem. At 12 feet (3.66 m) wide, just one Crusher track pod would be an exceptionally oversize load, requiring escort vehicles and advanced planning to move. The height of 12 feet 6 inches (3.8 m) would not be much of a problem, provided it was taken on a low load trailer, which it certainly would need be; weighing 200,000 pounds (90,000 kg), or 100 US tons (90.7 metric tons) dry, just one track pod is over four times the weight limit of even a modern flatbed trailer. It would require a specialized heavy trailer to move. The weight would not pose such an issue for movement by rail, but the width would be an even bigger issue than on the road. The track pod would overhang by several feet on either side of the railcar, meaning that all oncoming traffic would need to be stopped and rerouted, or put into a siding while the train carrying the Crusher parts passed, for fear of collision with the wide load. The same problem is encountered when trying to transport exceptionally large tanks, such as the French Char 2C, or the German Panzerkampfwagen Maus or Karl-Gerät by rail.
Once at a job site, the track pods were to be placed in a swamp so that they were easier to manipulate. The splined shafts were fitted in the sockets on one pod and the other pod is mated to it. They were bolted in place, and then the cabin supports and cabin could be dropped in from above. Electrical connections from the cabin were connected to the pods, the intakes and exhausts to the central recess, and the pusher bar was mounted.

The main points and key features of the design that are claimed in the patent were thus:

  • An amphibious vehicle with two independent, watertight propulsion units consisting of two sets of very wide tracks having only a narrow space between them, and the ability to fill with or pump out liquid to increase or decrease mass to the desired level.
  • Such a vehicle with the control cabin placed centrally on narrow supports between the two propulsion units.
  • Such a vehicle that has separate engines for each of the propulsion units.
  • Such a vehicle with a bar for pushing over trees.
  • Such a vehicle intended for crushing trees and undergrowth.
  • Such a vehicle with channels on the underside that contain support rollers for the use of tracks.
  • Such a vehicle that is joined together using the splined socket-and-shaft method.

The Heaviest Tracked Amphibian Ever Built

At 306 US tons (277.6 metric tons) fully loaded and 204 US tons (185 metric tons) dry, the Crawler-Crusher is the fourth heaviest amphibious vehicle of all time. It is surpassed only by the Aist-class LCAC hovercraft at 302.8 metric tons fully loaded, the Saunders-Roe N.4 Mk.III passenger hovercraft, at around 320 metric tons, and the Zubr-class LCAC hovercraft, which can weigh over 500 tons when fully loaded. The Crawler-Crusher is by far the largest and heaviest tracked amphibian of all time, vastly surpassing all other conventionally- (non-hovercraft) powered amphibious vehicles. For such a heavy vehicle, the Crawler-Crusher was surprisingly buoyant, able to float in just 7 feet 10 inches (2.38 m) of water. In terms of overall dimensions, the Crawler-Crusher was 58 feet (17.7 m) long, 24 feet (7.3 m) wide, and 22 feet (6.7 m) tall.


Source

It is not known precisely when the Crawler-Crusher was constructed, but we do know that it went into operation in April 1967. It cost $700,000 to build and employed many of the companies in Leesburg and the surrounding area. The Jacksonville Shipyard constructed the two-track pods, and most of the assembly work was done by Tucker’s Heavy Equipment Service (now Tucker’s Machine & Steel Service, Inc.) in Leesburg, Florida, with assistance from Leesburg Welding & Machine Company. Adams Air & Hydraulics from Tampa, Florida, did the hydraulic work, and Rozier Machinery Company, at the time a Caterpillar dealership, assisted in the construction by supplying Caterpillar parts.

In was not recorded as to what extent the built vehicle differed from the vehicle outlined in the patent, but there are some observations that can be drawn from photos. Most noticeably, the pusher bar is more heavily reinforced between the top legs of the A-frames. As already mentioned, the cabin is more competently built, and the vent lines do not appear to have been implemented. The controls for the engines and transmissions were electronically-operated hydraulics. Hydraulic pumps and generators were carried in the engine compartments, while the electronic equipment, spare parts, tools, and fuel was carried in the forward compartments.

During testing, the Crusher was found to overheat when it was especially hot out or the machine was worked continuously. Murray Tucker Sr. was discussing the issue at dinner one night when his son Charles Tucker overheard. Being a student at the Southern Technical Institute in Georgia, he asked his professor for help, who in turn assigned the problem to the class. They came up with the idea of running copper pipes down into the ballast water at the bottom of the machine; the engine coolant would be run through these pipes to disperse the heat into the ballast water. Charles informed his father about the solution.

“He acted like he knew it all along. He got the guys in the shop on it right away. He never did tell Mr. Gregg.” – Charles Tucker


F. Browne Gregg (left) and Murray Tucker Sr. (right) standing atop the Crawler-Crusher as the cabin is lowered into place by crane. Notice that the front face of the cabin is smooth and lacking the equipment that can be seen in other photos. Source: “Progress Through Innovation” by F. Browne Gregg

The completed Crusher was first demonstrated for a crowd of 300 people off of State Route 19, 15 miles (24 km) south of Palatka, Florida. Husebo Advertising & Public Relations organized the event that brought in news reporters from across the United States and Europe. The Crawler-Crusher exceeded every expectation, clearing 5 acres of land during the 1-hour demonstration — far more than the half-acre it was expected to accomplish. In both flooded swamp and dry land it left behind a smooth, clean surface.

The Crusher’s first and only job would be to clear the area behind Rodman Dam that would be known as Rodman Reservoir, Rodman Pool, or Lake Ocklawaha. The field supervisor from Gregg, Gibson & Gregg that saw over the use of the Crusher was a man named Jack Perko, the superintendent for the clearing overall was Andy Crabb. The Crawler-Crusher did its work extremely quickly, said to have been able to clear an acre or two of land an hour at a sustained rate. For it to clear 4,500 acres (7 square miles; 18.2 square kilometers) took between just 18 and 27 weeks.



“The Monster” and “The Tree Killer” were some of the creative nicknames given to the Crawler-Crusher by those who opposed the canal. Source

Able to mow over trees up to 6 feet (1.8 m) in diameter, or as many as eight 2 foot (0.6 m) diameter cypress trees at once, the Crawler-Crusher worked with such astonishing efficiency that it served as a rallying point for environmentalists. The Crusher exemplified to the public that the canal was not a long, drawn-out project that would be in the background for years, but was laying waste to the Ocklawaha on an unprecedented scale. Indeed, less than 15% of the trees in the area cleared for Rodman Reservoir were exploited; most were simply doused in diesel fuel and burned, or smashed by ‘Big Charlie’, as the Crusher became known by its operators.


Orange Springs Ferry was one of the first areas to be crushed. Source

Interestingly, one of the Crusher’s assigned jobs was to perform “mosquito control”. It did this by driving around the perimeter of the reservoir (or what would be the perimeter of the reservoir when the water level was between 20 and 21 feet above sea level) and mashing down the swamp forest so that pest control people could spray for mosquitos there. One founding member of the Environmental Defense Fund, which was formed to oppose the canal, was spurred to join the fight against the canal when on one of these mosquito patrols the Crawler-Crusher flattened Cause Springs, one of many natural sources of groundwater around the Ocklawaha, which he had been using as a personal pool!

Erika Ritter, a lifelong resident of the Ocklawaha, witnessed the destruction of the forest on the reservoir first hand when she was a child. Though she wasn’t old enough at the time to play a major part in the environmental movement to save the canal, since 2006 she has run pontoon boat tours on the Ocklawaha and Rodman Reservoir to educate the public about the impact of the canal. She recounts her experience with the Crusher as such:
Once we were in our small wooden boat watching the monster move along the river bank when its weight was too much for the bank and it caved into the river sliding sideways. The operators jumped out and climbed up top and it must have been full of water for maximum crushing weight as soon water started pumping out from various point in a large strong streams! The wave it caused across the river almost swamped our little craft as we cheered for its doom! It crushed everything in front of our house that we loved, I.e. springs, Creek Indian mounds, and [our] favorite fishing hole. They would park it in front of our place for safe keeping since it was an isolated area. We were informed not to come out in the canal clearing when the machine was moving due to the frequent busting off of bolts at a high rate of speed. The tracks had so much pressure on the bolts and breakage was common enough for safety concerns.


Erika Ritter, age 12, standing in front of the Crawler-Crusher while it was undergoing track repairs, October 20th, 1968. Source


Source

5,500 acres (8.6 square miles; 22.25 square kilometers) of land was cleared by the autumn of 1968, when Rodman Dam was completed on the 30th of September, and the reservoir was allowed to fill. Immediately, there was a problem. The trees that had been crushed into the mud by the weight of the Crawler-Crusher, intended to never be seen again, started floating to the surface. There had been a massive oversight during the design of the Crusher; the feasibility study that had been conducted used northern hardwood trees, while the trees along the Ocklawaha were primarily softwoods: gum, bay, pine, cedar, and cypress. The fact that it had been an unusually dry season, and thus the ground being harder than expected, was also cited by the Army Corps of Engineers as a reason for the tree crusher failing to work. Work continued with the tree crusher attempting to stomp the trees back into the muck, but they always came back up.

Despite this massive setback, which rendered the Crawler-Crusher useless as a means of making trees “go away”, work continued on clearing the canal and reservoir to the greatest degree possible. Some effort was expended with a barge-mounted crane and tugboat collecting the floating logs and burning them. The Crusher ran a methodical pattern, clearing a section 400 feet (122 m) wide and 12 feet (3.65 m) deep which would serve as the barge canal. On other portions of the reservoir, trees were left standing to serve as habitat for game fish. Meanwhile, the Army Corps of Engineers had been at work clearing trees from the banks of the Ocklawaha up to 20 miles (32.2 km) upstream from Rodman Reservoir in preparation to excavate and widen the stream to continue the canal.


The Crawler-Crusher wading through a field of floating trees on Rodman Reservoir, February 1969. Note that the pusher bar has been removed. Source

Rodman Reservoir was intended to be kept, under normal operation, at 20 feet (6.1 m) above mean sea level (note, this is not the same as 20 feet in depth), with a maximum of 22 feet (6.7 m) above sea level and an operational minimum of 18 feet (5.5 m) above sea level. At 20 feet, the reservoir covered about 13,000 acres (20.3 square miles; 52.6 square kilometers) of land and was 16 miles (25.7 km) long. At minimum draft, the reservoir covers about 9,200 acres (14.4 square miles; 37.2 square kilometers) and measures 15 miles (24.1 km) long and almost 2 miles (3.2 km) at its widest. The reservoir has been kept at 18 feet above sea level since 1969, with only brief periods of low water to prevent gunk from accumulating on the bottom.

In total, 5,500 acres (8.6 square miles; 22.25 square kilometers) of land was cleared and the rest of the reservoir was left standing; probably because attempting to clear it with the tree crusher would have only created more flotsam. To add insult to injury for the environmentalists that had opposed the canal the whole way, Rodman Reservoir was given the 1969 Army Corps of Engineers “Conservation of Natural Beauty Award” for leaving 5,500 acres of “natural wetlands” go uncleared, and merely putting them underwater. Of the roughly 7,500 acres (11.7 square miles; 30.35 square kilometers) of land that was not cleared, up to 2,000 acres (3.1 square miles; 8.1 square kilometers) have since drowned, leaving only decaying stumps where forest once stood.


Source

But Marjorie Harris Carr and her movement to save the Ocklawaha had one final ace in store. David Anthony was a biochemist from the University of Florida who had been in the field since World War II. With David’s scientific reason as backing, the Environmental Defense Fund (EDF) filed a suit in the United States District Court for the District of Columbia, seeking to halt all work on the Cross Florida Barge Canal. On January 15th, 1971, Judge Barrington D. Parker ruled in favor of the EDF, citing lack of statement regarding environmental impact, as required by the brand new National Environmental Policy Act. On January 19th, Richard Nixon formally ended the canal project. There was much political squabbling after the cancellation of the canal, with the invested parties attempting to reverse the decision, however, the canal project could never regain momentum, and no further work was done beyond finishing several bridges that were in the middle of construction.

In an ironic way, the symbol that had represented everything the environmentalists found wrong with the Cross Florida Barge Canal, the Crawler-Crusher, was a big part in their ultimate success at stopping it. The Environmental Defense Fund used the imagery of the Crusher to such great effect as ‘propaganda’, that it effectively turned public opinion against the canal itself.

Lasting Effects of the Canal and Fate of the Crusher


Press photo of the Crawler-Crusher near to or after the cancellation of the canal. Notice the damage done to the side panels and the bow in the tracks. Also notice the different exhaust structure; at some point it seems to have been rebuilt and extended forward past the cabin for some unknown reason. Source

With Rodman Dam and Reservoir completed, it very quickly became apparent that the environmentalists’ warnings were correct. What hardwood trees remained around the area died off due to being overwatered. Hydrilla and common water hyacinth, highly invasive aquatic weeds, flourished in the shallow, still water. At 18 feet (5.5 m) above mean sea level, the level at which Rodman Pool has usually been held at since its construction, the dam causes a backwater effect (water in a river being held higher than it normally would be) for about 2 miles (3.2 km) downstream, and, though there is debate, about 0.5 miles (0.8 km) upstream as well.

Work on Eureka Dam continued until it was halted in 1970 just shy of completion. It is unknown if there had ever been talk of using the Crawler-Crusher at Eureka as well, but after its utter failure to crush trees effectively at Rodman, it is more likely to have been kicked off the project.

Apart from Rodman Dam (later renamed George Kirkpatrick Dam), the aforementioned Eureka and Inglis Dams, and Buckman Lock, there are three bridges over the Ocklawaha that were built as part of the Cross Florida Barge Canal project that still exist today. These are: the bridge that carries State Road 19 over the canal between Buckman Lock and Rodman Reservoir, the bridge that carries County Road 316 over the Ocklawaha south of Rodman Reservoir, and the Bert Dosh Memorial Bridge on State Road 40 near Silver Springs. All three of these are “high bridges”, meaning they are high enough that barge traffic would have been able to pass underneath. Often thought to be part of the Cross Florida Barge Canal, concrete bridge supports that were poured in the 1930s as part of the Atlantic-Gulf Ship Canal still exist in the wooded area where U.S. Route 301 splits around the Marion County Sheriff Office south of Ocala, Florida.

Even though nearly 50 years have passed since the Crusher finished its work on Rodman Reservoir, its influence can still be seen today. One half of the reservoir is dotted with the stumps of trees drowned out by the raised water level, as well as what patches of forest have managed to cling on, while the other is an endless maze of splintered, floating, and half-sunken trees. These are the same trees that felt the weight of the tree crusher all those years ago, unable to be removed or crushed, they were left in the water, and have posed a hazard to boat traffic for the entire history of the reservoir. This desolate swampland has become suitable habitat for water birds, such as egrets, ibises, grackles, and anhingas, but does not make up for the destruction of the forest and river that was once home to many more species of birds, amphibians, and fish.



Photos of Rodman Reservoir taken during a “drawdown” by Raymond Powers in 2016. Source

The remains of the Cross Florida Barge Canal, especially Rodman Reservoir, remain a hotly debated topic, with people on both sides unwilling to waver in their convictions that the dam should come down or remain up. While it was never used as a shipping lane, or as a recreational lake, Rodman has become a competitive fishing hotspot, known for being chock full of prized largemouth bass. Undoubtedly, the fishing industry holds some sway over Rodman Dam’s continued existence.

As for the Crawler-Crusher, whether it inspired horror or awe, it left a lasting impression on the people of Central Florida, and many wondered what became of it once the canal was canceled. Like many grand machines, whether you agree with its purpose or not, it represented man’s ingenuity and accomplishment, and, like in the story of HMS Warspite making a break for the North Sea, people don’t want to see those accomplishments go gently into the dark night. There were several rumors as to what happened to the Crusher; some people said it went to Texas, or to South America, and was being used there to clear areas for reservoirs and canals; some people believed it had been moved out to Flagler Beach to work on the Intracoastal Waterway, and was abandoned on a spoil island somewhere; and others claimed it went to Vietnam, to support the war effort there. The real fate of the Crawler-Crusher is much less glamorous; with no work left to do, it sat disused for about a year and was scrapped circa 1971. No remnants of “The Monster” are known to exist, save for the thousands of acres of broken trees where it once trod.

One user on heavyequipmentforums.com claims that a friend of a friend was in Florida at an unspecified time and came across massive track links, 10 feet (3 m) wide, in a scrapyard there. There are very few vehicles in history, let alone in Florida, that had tracks that fit this description. In fact, the Crawler-Crusher exceeds this guesstimate, having tracks 11½ feet wide (3.5 m) wide, indicating that at the very least, Big Charlie’s tracks may have hung around for a while even after the machine itself was gone.

In his autobiography, F. Browne Gregg claims that Joe Rozier, the owner of the Caterpillar dealership that helped in building the Crawler-Crusher, was able to put Gregg in touch with the United Nations. He says that at the time the UN was anticipating a famine that would occur in Asia within three to five years. The UN’s interest in the Crusher was to use it to prepare rice paddies in Indonesia.

Gregg met with UN representatives in Hong Kong, where he was offered a contract to produce 500 Crushers in 18 months. In addition to a “mighty tempting” amount of money, he would be allowed to take tax-free ownership of the manufacturing facilities in three years. Even though each Crusher would sell for about 2 million dollars, Gregg passed on the offer due to the work being too momentous, and because it would have taken time away from his other businesses and his family. Perhaps this was the origin of the rumor that the Crawler-Crusher escaped to Vietnam.

The Man Behind The Monster

Frederick Browne Gregg was born on August 13th, 1922, in Lake Junaluska, North Carolina, to William Carter Gregg and Myra Lees Browne Gregg. He suffered from severe dyslexia as a child, something that shaped his life and forced him to think differently from most people. His family moved to Leesburg, Florida, when he was only a year or two old. Frederick graduated from Leesburg High School and started college at The Citadel in Charleston, South Carolina. When Frederick was 20 years old the United States entered World War II. On August 7th, 1942, he applied to the US Army Air Corps in San Antonio, Texas; then went on to pilot a B-26 Marauder, fulfilling his dream of flying. He would fly 37 missions, despite being shot down twice; he earned five Air Medals and was awarded a Silver Star in Paris for engaging with an Me 262 jet fighter. Frederick’s plane, B-26 serial number 43-34190, tail number KX-N, was leading a formation of 108 bombers when they were jumped by an Me 262 of KG(J) 54, supposedly flown by jet ace Heinrich Bär. The 262 downed the flight’s deputy lead aircraft, killing all but one of the crew, and heavily damaged Gregg’s B-26, counting it as a probable kill. With the Silver Star in 1945 he was promoted to the rank of Captain. After the war, Gregg came home to the States aboard RMS Queen Mary.
On January 1st, 1946, he was married to Juanita Osborne. He invested his military savings, about $4,000, into starting an outdoor furniture manufacturing business out of his parent’s garage. Later, Frederick Gregg, his brother Bill (William) Gregg, and their friend Brunson Gibson, with some help from the third Gregg brother, James Gregg, formed Gregg Gibson & Gregg Inc., a construction-oriented business that produced sand and concrete products and provided trucking and dredging services. This would set the tone for the remainder of the business ventures Frederick would undertake in his life.

Under Gregg Gibson & Gregg Inc. was where Frederick would make his most radical inventions; the Crawler-Crusher, and The Triton, the latter being the world’s largest dredge at the time. The Triton was constructed in 1968 around a surplus World War II destroyer engine to fulfil a $5 million excavation contract issued by the Army Corps of Engineers, the largest ever issued in Florida at the time. Gregg sold the company in 1969.


The Triton dredge. Source

In 1971 he purchased Camp Concrete Rock Co., a small mining operation; out of this was formed Frederick Gregg’s most famous company, Florida Crushed Stone. As the Florida Crushed Stone Company grew, it acquired several other companies, including Consolidated Minerals Inc., which still survives today. Florida Crushed Stone became central Florida’s leading producer of construction aggregates (quite literally, crushed stones; aggregates include concrete and sand).

During the 1980s, Frederick Browne Gregg and Florida Crushed Stone undertook the project they are remembered for best in the construction industry. This was reengineering Central Power & Lime of Brooksville, Florida, as the world’s first integrated power, cement, and lime plant. The rebuild of the plant cost $250 million and involved rebuilding and moving a disused coal-fired electric power plant from Illinois to Florida. The plant’s primary innovation though, was the fact that it operated almost entirely off of waste materials.

In 1994, Browne Gregg was involved in a plane crash that broke his neck and collarbone. Within months, he was skiing with his family in Colorado, despite having to wear a neck brace and being 72 years old.

Not all of his business ventures were successful; he caught criticism from local Floridians for his involvement in the Lake County incineration plant, which, despite being paid for by public funds, remained a private entity. Gregg sold his interests in the plant to Covanta Energy, which still operates it today.

Frederick sold most ownership of the Florida Crushed Stone Company to CSR America in 2000, though he retained some of its operations and combined them with his other businesses as Consolidated Minerals Inc. Today, Consolidated Minerals also owns CL Industries, the largest American manufacturer of pool finishing materials.

Frederick Browne Gregg’s wife Juanita passed away in 2000; he later remarried to Victoria McDonald Gregg. Frederick himself passed away on October 10th, 2014, at the ripe old age of 92. Arrangements were made by Beyers Funeral Home and Crematory. He was laid to rest at Hillcrest Memorial Gardens Cemetery in Leesburg, Florida, on October 15th, 2014, following a funeral at the Morrison United Methodist Church.


Source

F. Browne Gregg is remembered as a kindhearted and enthusiastic inventor and businessman. He and his companies have won many awards, including the Ernst & Young Entrepreneur of the Year Award, Socially Responsible Award, Florida Region for 1995; the Junior Achievement Mid-Florida Business Hall of Fame in 1998; an induction to the Texas Panhandle Veterans Hall of Honor; and several appointments to the Florida Council of 100. He was a benefactor of children’s education and medicine, and made regular contributions to Camp Boggy Creek, Junior Achievement of Central Florida, and Green Isle Children’s Ranch.


Probably the most famous photo of the Crawler-Crusher, showing its destructive power. Gregg’s wife Juanita created an oil painting copy of this photo that hung in Gregg’s office until his death. Source

Crawler-Crusher Specifications

Dimensions 58 x 24 x 22 ft (17.7 x 7.3 x 6.7 m)
Total weight 306 US tons
Crew 1+ (driver-operator, mechanic)
Propulsion 2x Caterpillar D432 270 hp Diesel Engines, 540 hp total
Suspension None
Total production 1
For information about abbreviations check the Lexical Index


Sources

“From Exploitation to Conservation: A History of the Marjorie Harris Carr Cross Florida Greenway” by Steven Noll and M. David Tegeder
“Cutting Through Paradise: A Political History of the Cross-Florida Barge Canal” Doctoral Dissertation by Sallie R. Middleton
“Ocklawaha River Cross Florida Barge Canal Structures” Webpage Report, Paul Nosca, 2015
“‘Our Lady of the Rivers’: Marjorie Harris Carr, Science, Gender, and Environmental Activism” Doctoral Dissertation by Margaret F. MacDonald
Summer 2004 Issue of The Florida Historical Quarterly
Pure Florida Blog’s entry on Rodman Reservoir
River be Dammed.org’s page on the history of Rodman Reservoir
US Patent 3418961A for Swamp Clearing Machine
“Progress Through Innovation” by F. Browne Gregg
Popular Science, April 1968
Heavy Equipment Forums.com
Consolidated Minerals Inc. Page on F. Browne Gregg
Frederick Browne Gregg’s Obituary
Contractors and Engineers Magazine, March 1970 Issue
The author would like to express thanks to Erika Ritter for supplying photos and for recounting her memories of the Crusher.


Illustration of the gargantuan Crawler-Crusher – otherwise known as “The Monster”, produced by Andrei ‘Octo10’ Kirushkin, funded by our Patreon Campaign.

Categories
Modern US Improvised AFVs

CV-990 Tire Assault Vehicle (TAV)

USA, NASA (1995)
Research Drone – 1 Built

By 1993, the U.S. National Aeronautics and Space Administration’s (NASA) four Space Shuttles, Columbia, Challenger, Discovery, and Atlantis, as well as a fifth, Endeavour, which made its inaugural flight less than a year earlier, held between them over 50 completed missions. The Space Shuttles very much formed the backbone of NASA’s space operations. Like all spacecraft, the Shuttles were upgraded throughout their lives. Every system and component was trialed and tested to its breaking point to see if it could be improved. In 1993, it was the humble tire that came under the knife.
The Space Shuttle’s tires weren’t just any tires; having to go to space and back meant that they had to be tough. Each tire, of which there were six, could support over 64 metric tons. The pressure inside the Michelin-brand tires was 340 psi (23.9 kg per square centimeter).
To test the Shuttle tires, NASA roped in an old medium-altitude atmospheric testing aircraft, a modified Convair 990 Coronado narrow-body airliner with the tail number NASA 810. NASA 810 was modified into a landing systems research aircraft or LSRA. Its job was to test the brakes, landing gear systems, nose wheel steering control, and overall durability of the Space Shuttle’s tires. Tests of the Shuttle tires with the Convair 990 LSRA began in April 1993 at NASA’s Dryden Flight Research Center at Edwards Air Force Base in California. The CV-990 LSRA, flown by astronaut and test pilot Charles Gordon Fullerton, completed 155 missions by the close of the program in August 1995.

View of the underside of CV-990 LSRA ‘NASA 810’, showing the Space Shuttle wheel suspended on a special hydraulic assembly between the airliner’s normal landing gear, April 1993. Photo: SOURCE

NASA 810 before it was modified into a landing systems research aircraft, July 1992. Photo: SOURCE
When tires are tested to their limits, blowouts are to be expected; and when there’s enough force behind that blowout to rip limbs from their sockets and hurl massive chunks of rubber hundreds, if not thousands, of feet, one should obviously err on the side of caution. The most dangerous tires were the ones that seemed to survive the tests. Outwardly, a tire could appear completely intact, while on the inside it is ready to burst. Extreme wear, as well as heat and the resulting pressure changes, could weaken the tire to the point that even touching it could cause it to fail. Even allowing the hot tire to cool could be sufficient stress leading to a rupture.
NASA tried several simple ways of safely detonating the tires, but they did not always work, and could even be dangerous. A 450 lb (204 kg) bomb disposal robot, worth 100,000 U.S. dollars, was available to the CV-990 LSRA crew, but it was often preoccupied when they needed it. In addition, the bomb robot was 4 feet (1.22 m) tall, 4 feet (1.22 m) long, and 3 feet (0.91 m) wide, making it too large to effectively maneuver under the plane.

The Last Operational Use of the King Tiger… Kind of

This problem, as with most problems when you put your mind to it, was solved with heavy armor. Not just any heavy armor, the heaviest and most fearsome tank of the Second World War, the King Tiger, albeit made of plastic and much smaller than the original.
David Carrott, a portable radio communications expert contracted by NASA, stepped forward with a way to puncture stressed Shuttle tires coming in off the LSRA. Carrott bought a Tamiya 1/16th scale remote controlled Tiger II (Item No. 56018), retailing at around 1,000 U.S. dollars, and used it as a base to build a tire-popping robot. He built the lower portion of the hull, the suspension, tracks, and rear plate, but forwent the rest, using approximately 25% of the original model’s parts. He then fabricated a metal piece resembling an inverted “U”, which took the place of the upper hull sides and roof. Another metal piece was cut out in the shape of the upper frontal plate and welded to the front of the machine. The use of metal for the hull of the machine was presumably to protect it from debris from exploding tires, which could easily have destroyed it were it made of plastic. Side skirts also made of metal were attached above the tracks with 9 rivets per side. The reason why Carrott thought the vehicle needed side skirts is unknown, though some have theorized it was to keep any stray wires or debris out of the tracks. An interesting detail to note is that the side skirts seem to have been custom ordered, as on the top of the right skirt is what appears to be a NASA-tagged barcode.
The “weapon” of the machine was a DeWalt power drill with a 3/8 inch (9.53 mm) bit. Power was provided by a single 12 Volt, 7 Ah, Black and Decker VRLA rechargeable battery. The handle of the drill was removed and the remaining portion mounted above the radio operator’s area on the right-hand side of the model tank chassis. To the left of the drill was a small pod containing a video camera as well as a transmitter.
Two other Black and Decker/DeWalt electric drill motors were employed to propel the tank, one driving each track through a geared transmission. The motors driving the tracks as well as the drill were all controlled through three separate custom solid-state VANTEC speed controllers. All onboard equipment, such as the video camera and the motors driving the tracks, were powered by the drill battery protruding from the engine deck.
The controller was a JR X388S transmitter and receiver operating on government frequency. The signal from the camera was received by a down-converter and turned into a composite video. A portable black-and-white television displayed the video feed to the operator.
The whole machine was built for under 3,000 U.S. dollars. It weighed 20 pounds (9.1 kg), and was 12 inches (30.5 cm) high, 18 inches (45.7 cm) long, and 8 inches (20.3 cm) wide. Carrott called his creation the CV-990 Tire Assault Vehicle. It was referred to as the TAV for short.


Illustration of the ‘Tire Assault vehicle (TAV)’ by Bernard ‘Escodrion’ Baker, funded by our Patreon campaign.

Use

The TAV was available for 32 of the 155 Shuttle tire test missions. While it only operated from February to August of 1995, catching the tail end of the test missions, the TAV performed its role flawlessly. It safely detonated 9 “live” tires, 4 of which were extremely volatile, and could have endangered the lives of any persons who would have had to go in to defuse them had the TAV not been present.
There is only a single known photo of the TAV in operation (shown below). In it, the camera is seen mounted on an elevated bracket at the far rear of the machine. In place of where the camera is normally seen, to the left of the drill, is what appears to be an infrared thermometer. This would make sense, as the temperature is directly related to pressure inside a tire, monitoring the temperature also allows you to monitor the pressure. Is it possible, probable even, that the TAV used this configuration for most or all of its service life, only being reconfigured after the Shuttle tire tests were finished. It is equally probable that it was reconfigured depending upon the exact situation which it faced.

The Tire Assault Vehicle moving in on a Shuttle tire after Test Flight 145, July 27th, 1995. Photo: SOURCE

Legacy

The tests performed with the Space Shuttle tires between 1993 and 1995 provided a large amount of data. Most notably, the knowledge of the exact behavior of Shuttle tires allowed the crosswind limit for the Shuttle, that is, the maximum speed of wind crossing the runway parallel to the landing aircraft deemed safe to land in, to be increased from 15 knots (17.3 mph, 27.8 kph) to 20 knots (23 mph, 37 kph).
Life as a landing systems research aircraft would be the final mission for NASA 810; after completion of the program, it was retired. It now stands as a gate guard at the Mojave Air and Space Port in California.

NASA 810 as she sits today at the Mojave Air and Space Port, March 2017. Photo: SOURCE
Remarkably, the TAV survives as well. It is located in a plexiglass box in the gift shop of the Air Force Flight Test Museum at Edwards Air Force Base in California, where it spent its entire operational life.

The TAV in its display case at the Air Force Flight Test Museum, Around May 2017.

The plaque at the foot of the TAV display case. Photo: SOURCE

Links & Resources

www.nasa.gov
www.nasa.gov/imagegallery
www.nasa.gov/pastprojects
www.nasa.gov/NewsReleases


German King Tiger Tank – Tank Encyclopedia Support Shirt

German King Tiger Tank – Tank Encyclopedia Support Shirt

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Categories
WW2 German prototypes

German Tank-based Railway Guns

German self propelled guns of ww2 Nazi Germany
Self-propelled superheavy siege guns – None Built

“It seemed like a good idea at the time”

Times of war can lead to unorthodox solutions to unforeseen problems. Sometimes these are successful; the Duplex Drive tank, the jet engine, night vision, and reactive armor. Sometimes these aren’t so successful…
The designs talked about here are not among the former. This article is a collection of little-known projects by Nazi Germany to mount naval artillery, super heavy siege cannons, and railway guns on the combined chassis of two or more tanks. These designs are quite obscure and do not have enough information to warrant their own individual articles.

Projekt NM

Coming from 1943 is possibly one of the strangest ground fighting vehicles ever designed; the Project NM was a massive wooden warehouse structure atop a steel girder frame transported by three turretless Tiger Ausf.E tanks. The entire assembly measured about 17 meters wide by 15 meters long. Inside the wooden warehouse were three turrets mounted line abreast armed with 12.8 cm cannons. The center turret was slightly staggered behind the other two. The cannons pointed back over the rear of the vehicle, poking out through the doors of the warehouse. At the ‘front’ was a single Tiger tank while the other two Tigers were under the rear.
There are two schools of thought as to what the purpose of this vehicle was. The first is that it was destined for use on the plains of the Eastern Front, but there are several problems with this. Firstly, a large warehouse slowly creeping across a field isn’t very inconspicuous. Second, the NM would be unable to cross rivers, neither by fording, due to the rigidity of its construction, nor by bridges, due to its width. As a rigid structure, the NM would be unable to cope with all but the slightest changes in ground slope.
The second possible use for the vehicle is as a mobile coastal defense installation, for example as part of the Atlantikwall. This seems the more reasonable use, as a warehouse on the coastline isn’t likely to draw attention. Just who the project is attributed to is unknown as well, whether it was the Heer (Army) or the Kriegsmarine (Navy). Suspected use, armament, and the name all point to it being a Kriegsmarine project. The Kriegsmarine often designated their projects with capital letters, while the Heer did not. The armament, consisting of three 12.8 cm guns in separate turrets is another indication that the NM was a Kriegsmarine project. The Kriegsmarine referred to all their 128 mm guns as 127 mm guns, probably in order to avoid confusion with the Heer’s cannons. Assuming the NM was a Kriegsmarine project, its armament would have been either 12.7 cm SK C/34, or 12.7 cm SK C/41 cannons, though the former is the more likely choice, as they were more widely used.
Operationally, the NM would likely be deployed to a coast region where an attack was expected, or where the defense needed strengthening. The vehicle would be reversed into position and possibly camouflaged to best appear as a non-threatening structure. When an enemy vessel was within range the doors of the warehouse would be opened, giving the guns a reasonable firing arc. The NM would have time enough to fire a few salvos before the enemy vessels finally realized they were being engaged by a warehouse and not surface vessels or gun emplacements. When return fire started coming in, the NM could drive forward to move itself out of the line of fire.
Unsurprisingly, attaching three Tiger chassis together with steel girders and putting a warehouse on top wasn’t seen as a very practical idea. The NM Project did not advance any further.

Projekt NM Blueprint (Source: Der Panzerkampfwagen Tiger und Seine Abarten – Walter J. Spielberger, 1997)

Tiger H als Tragfahrzeug für schwerste Geschütze

In January 1941 (perhaps this was a typo for 1942, as the project is only mentioned again in December of 1942, nearly two years later), the Waffenamt (German Army Weapons Agency) put out a requirement for a system for transporting the 24 cm Kanone 4.
The K 4 was a project to upgrade the underwhelming 24 cm K 3. Only 14 K 3 guns were built; the reason being was that they were much more time-consuming to set up and operate than comparable guns such as the 21 cm Mörser 18, while their advantage in performance was not significant enough to warrant the hassle. Little information is available on the K 4, other than basic measurements. The barrel length was a ‘L/72’ meaning it was 72 calibers long. (72 x 24 cm gives a total barrel length of 17.28 m) and the gun was meant to fire 160 kilograms (353 lb.) shells up to 49 kilometers (30.4 miles).
Both the firms of Krupp and Rheinmetall-Borsig responded to the requirement. Krupp’s design was to use two unarmored Panzer VI Tiger chassis; while Rheinmetall’s design used the Karl-Gerät chassis. Further information on Rheinmetall’s design is unavailable; presumably, it was rejected early on due to the Karl Gerät chassis being too slow and unmaneuverable.
On the 17th of December, 1942, the OKH (German Army High Command) sent letter Wa J Rü (WuG 6) Villa2 Nr. 9846/42 to Henschel, the manufacturer of the Tiger chassis, requesting the necessary parts to build a prototype. Assembly of the vehicle was to take place at one of Krupp’s plants. The order was signed under the name “Tiger H als Tragfahrzeug für schwerste Geschütze”, or “Tiger H as a carrier for the heaviest guns”.
Krupp’s design aimed to have greater speed and mobility than the lackluster Karl Gerät. The unarmored Tiger chassis weighed 25 tons each. In order to prevent one tank moving while the other wasn’t, which would have damaged the machine, the drive units of each chassis were intended to be hydraulically linked to stay at the same speed. The projected top speed was 30 to 35 kph (18.6 to 21.7 mph). Hydraulic jacks were to be installed in place of the turret in the Tiger chassis; these would support large cylinders which in turn supported the gun platform. The gun platform could be lowered onto its base plate and the Tigers driven away with minimum difficulty. Four outriggers would be deployed to stabilize the gun. Whether or not the gun had any reasonable degree of traverse once in firing position is unknown.
The gun platform was lowered in the center, like a heavyweight railroad flatcar, but even so, the assembly was more than twice as tall as a normal Tiger tank when in transport configuration. Additionally, the ground pressure for each unarmored unit was significantly higher than a normal Tiger tank. However, being too heavy to cross bridges was not seen as a concern as only one load-bearing unit would be on the bridge at one time, due to the vehicle being so long. The distance between the centers of the Tiger chassis was to be 20 to 22 meters (65.5 to 72.1 feet), to give a sense of scale, a normal tractor-trailer truck trailer is 53 feet, or 16.1 meters long.
On the 23rd of December, 1942, Henschel stated that they would be unable to produce more Tiger chassis for a Lastenträger vehicle alongside of normal Tiger production, as they were already at full capacity.
A single prototype of the K 4 was being constructed at Krupp of Essen, but this was destroyed in a bombing raid in March 1943. With the destruction of the prototype, the K 4 project was canceled. If it had not been canceled already, this was surely the death of the Tiger H als Tragfahrzeug für schwerste Geschütze as well.

24 cm Kanone 4 mit Lastenträger Tiger I (Drawing Copyright Hilary Louis Doyle)

Gerät 566 Lastenträger 606/5 für K 5/3 (Tiger)

As the first design was canceled due to the discontinuation of the intended weapon, and not because it was ridiculous and impractical, Krupp decided to persevere with the tank-based railway gun idea using the 28 cm K 5 instead. The K 5 (sometimes incorrectly referred to as Leopold – this was the name of an individual railway gun rather than the name for this system) was the most successful railway gun of World War II; 25 pieces were built in total. The railway version of the gun weighed 218 metric tons; this number is probably not far off from the weight of the tank-based gun had it been built.
To transport the K 5 Krupp chose the Panzer VI Tiger II chassis. The general construction was similar to that of the first design, however, it seems the second design had even thinner support cylinders. Coupled with the immense weight of the K 5, it is even more unlikely the mechanism for raising the gun into transport position and lowering the gun into firing position would be functional and reliable.
Note: The book ‘Der Panzerkampfwagen Tiger und Seine Abarten’ (Spielberger, 1997) seems to suggest that the gun barrel, gun carriage, and base plate were all transported separately. However, the same book shows the illustration below, which implies that the whole assembly was transported as a single unit. Transporting the weapon in pieces would help overcome the problems of its great size and weight, but would make assembly upon arrival a nightmare. The book also states that a separate Tiger II-based vehicle would bring along “closing pieces” for the gun.
The Gerät 566 Lastenträger 606/5 für K 5/3 (Tiger) would have used a late-war development of the K 5 gun; the K 5 Glatt. The K 5 Glatt had a 31 cm smoothbore gun tube that was designed to fire 136 kilograms (300 lb.) subcaliber fin-stabilized rounds called Pfeilgeschoß up to a range of 120 to 150 kilometers (74.5 to 93.2 miles). This was great enough range to fire on London. However, due to the implementation of the V1 ‘Buzz Bomb’ and V2 missile, the K 5 Glatt fell by the wayside. Only two were built, both in railway configuration.

28 cm Kanone 5 mit Lastenträger Tiger II (Drawing Copyright Hilary Louis Doyle)

28 cm DKM 44 auf Panther Langholzprinzip

This design comes from a drawing dated from September 1943, wherein Rheinmetall-Borsig proposed that two Panzerkampfwagen Panther chassis be used to transport their 28 cm Düsenkanone Marine (DKM) 44 recoilless coastal defense gun, then under development in Sömmerda for the Kriegsmarine.
The 28 cm DKM 44 was the largest recoilless cannon being developed in Germany at the time. Rheinmetall-Borsig was the primary, possibly only, firm conducting work on recoilless guns in the later half of the War. They were under contract by the Luftwaffe, Heer (Army), and Kriegsmarine to develop different calibers of recoilless guns for various uses. The two projects Rheinmetall-Borsig was working on for the Kriegsmarine were the 8,8 cm DKM 43, a cannon for small vessels that would normally not mount larger weaponry than machine guns, and the 28 cm DKM 44, a coastal defense gun to defend against enemy landing forces.
The 28 cm DKM 44 would have weighed 28,000 kg (28 metric tons), it had 10 degree barrel rifling, and an electrical ignition system. It was designed by Herr Osthues, and the ballistician for the gun was Engineer Weber. A prototype of the DKM 44 was apparently completed before the end of the war by Hanomag in Hanover, and had even undergone tests. Photographs and blueprints should exist for this gun, but as yet they have not been found.
It is not known where the idea to transport the gun with two Panther chassis originated, whether from Rheinmetall-Borsig or suggested by the Kriegsmarine. More likely it was the former, as the Kriegsmarine, with the exception of their other project on this page, the NM, normally had no involvement with tanks.
The name of Rheinmetall’s design was the 28 cm Düsenkanone auf Panther Langholzprinzip, which translated to English means 28 cm Recoilless Cannon on Panther Long Wood Principle. “Langholzprinzip” is the German term for the practice used in logging whereby fallen trees are attached to a truck at one end and to an independent set of trailing axles at the other. By doing this the logs are allowed to support themselves between the axles and negate the need for a trailer. This same principle was employed on the 28 cm Düsenkanone auf Panther, with one tank taking the place of the truck, and the other taking the place of the trailer, leaving the payload slung between them.
The first Panther had a support that would attach to a collar half-way up the 28 cm DKM 44’s barrel, while the second Panther had a large, crane-like structure that would hold the gun’s breech from above. In order to fire, the gun would be lowered to the ground by large hydraulic rams inside the hulls of the tank chassis. The Panthers would then disconnect from the gun and move away. The cannon could then be used as a normal gun emplacement, able to rotate on its pedestal. Inside the gun’s superstructure was stored 10 two-piece rounds.
There is no surviving evidence if this design was accepted to be the main mode of transporting the DKM 44, however there are very few alternatives for moving such a big gun. Nevertheless the War did not progress in Germany’s favor; the DKM 44 never became operational, and its function as a coastal defense gun was no longer needed.

28 cm DKM 44 auf Panther Langholzprinzip Blueprint Source

Epilogue

Nazi Germany is remembered, among other things, for hideously impractical, ludicrous ‘wonder weapons.’ The idea of making railway guns mobile by sticking multiple tanks together is probably one of the weirdest. In the end even the Nazis had enough sense to see that these designs were hopelessly impractical.
However designs for vehicle-based super heavy siege guns did go on, with such things as the 58 ton Grille 17/21, the 182 ton R 2, and the 1500 ton Landkreuzer P.1500. None of these designs made any impact on the course of the war; only the Grille 17/21 was partially built while the others remained on paper. The only design of this type to become operational, the Karl Gerät, remains a lasting symbol of Hitler’s megalomania and the embracing of unconventional designs by the Third Reich’s war machine.

Sources

Les Armes secrètes du IIIe Reich: Hitler aurait-il pu gagner la guerre? – Laurent Tirone, 2014
Enzyklopädie Deutscher Waffen 1939-1945: Handwaffen, Artillerie, Beutewaffen, Sonderwaffen Gebundene Ausgabe – T.J. Gander and Peter Chamberlain, 2008
Der Panzerkampfwagen Tiger und Seine Abarten – Walter J. Spielberger, 1997
Panther Variants 1942-1945 – Osprey New Vanguard, 1997
Germans Tanks of ww2
Germans Tanks of ww2


Tank Encyclopedia’s own illustration of the 28 cm DKM 44 auf Panther Langholzprinzip by Jaroslaw Janas.

Categories
WW2 German prototypes

Waffenträger Panthers – Heuschrecke, Grille, Skorpion

German ww2 tanks Nazi Germany (1942-45)
Self-propelled weapon carriers – Several Wooden Mockups built

Animal Farm

In early 1942 Wa.Prüf 4, the German organization in charge of field artillery, put forward a design requirement for a vehicle to move heavy artillery. The main stipulation was that it should use parts from the new Panther medium tank. A similar competition was already underway for a vehicle to move lighter field artillery, such as 10.5 cm guns, using the Geschützwagen III/IV chassis. This had inspired Wa.Prüf 4 to do the same for a vehicle to move heavier 12.8 cm and 15 cm artillery pieces, as the Geschützwagen III/IV was too small to handle them. The guns in question were the 12.8 cm K 43 and 15 cm sFH 43. The sFH 43 (schwerer Feld Haubitze, heavy field howitzer) was a projected improvement on the 15 cm sFH 18, the new gun was to use bagged propellant and had a screw-type breech. The 12.8 cm Kanone 43 is unknown in most literature but is presumably a predecessor to the 12.8 cm K 44 L/55. Neither of these cannons were ever built.
In order to keep weight down, the designs were to be open-topped. Prototypes were to be built using Panther parts, but it was projected that any serial production vehicles would be made using the Panther II chassis. This idea was discarded when the Panther II was cancelled in June of 1943.
Both Krupp and Rheinmetall-Borsig took part in this design competition. All designs were able to be transported by rail with a few adjustments, and all could carry at least 30 rounds, however, Rheinmetall’s design had trouble with this.
Despite these vehicles being colloquially known as waffenträgers, very few designs carried the name waffenträger in their designation. Despite “waffenträger” literally meaning “weapon carrier”, most German weapon carriers were called Selbstfahrlafette, meaning “self-propelled gun carriage”.

Krupp’s Cricket – (Sfl.) Krupp I and II

Krupp immediately set to work and on July 1st, 1942, came up with the 12.8 cm K 43 (Sfl.) Krupp I (indexed Gerät 5-1211) and 15 cm sFH 43 (Sfl.) Krupp I (indexed Gerät 5-1528). Both vehicles were nearly identical, only differing in armament. Both vehicles had a dismountable, 360-degree rotating turret and muzzle brakes on their cannons. The 15 cm sFH 43 (Sfl.) Krupp I’s 15 cm sFH 43 L/35.5 had a range of 18 km (11.18 miles). The chassis was called Bauelemente Fahrgestell Panther, literally “components of the Panther chassis.” No blueprints of these vehicles survive, leaving their appearance a mystery.
Shortly after designing the first vehicles, Krupp produced another version, the (Sfl.) Krupp II. Again, the 12.8 cm K 43 (Sfl.) Krupp II and 15 cm sFH 43 (Sfl.) Krupp II were identical except for armament. This second design also had a fully traversable dismounting turret. The chassis was also lengthened slightly, giving a wheelbase of 4,200mm. A full-scale wooden mock-up of the 12.8 cm version was built in November 1942 and shown to Wa.Prüf 4 in January 1943. At this time Krupp stated they could have a working prototype ready by the 1st of September if they received the needed Pather components by the 1st of May, 1943.

12.8 cm K 43 Selbstfahrlafette Krupp II/Grille 12 (Drawing Copyright Hilary Louis Doyle)

15 cm sFH 43 Selbstfahrlafette Krupp II/Grille 15 (Drawing Copyright Hilary Louis Doyle)


Grille 12 Wooden Mockup
On the 18th of February, 1943, an order was placed for the construction of two (Sfl.) Krupp I prototypes; one 12.8 cm and the other 15 cm. On February 24th, 1943, Wa.Prüf 4 informed Krupp of the cover names that were assigned to their projects. The (Sfl.) Krupp I was named Heuschrecke (Grasshopper), and the (Sfl.) Krupp II was named Grille (Cricket).


These blueprints, from November 25th, 1942, show the existing Grille 15 design on top, and on the bottom show an improved version proposed on the 11th of November. The November 11th design has the fighting compartment 15mm lower and slightly forward than that of the existing design, it is also equipped with a new type of muzzle brake. Whether or not this proposal was incorporated into the Grille 15, we do not know at this time. Source



This set of blueprints show the process by which the gun assembly would be dismounted. The vehicle’s gun barrel would be used as a jib. A block and tackle would be attached to allow it to lift the metal frame pieces off the front of the hull and put them in position behind the turret; forming a ramp. Wheels would be attached to the turret pedestal, and a winch on the hull would lower it down the ramp. Once off the vehicle, support legs could be attached to the turret pedestal allowing it to be used as a field gun. Overall a quite complicated process. Source
On the 11th of March, 1943, due to concerns that production of the new 15 cm sFH 43 would be slow, Wa.Prüf 4 requested that the option of mounting the older 15 cm sFH 18 on the Grille 15 be looked into. By April 20th it was determined that utilizing the sFH 18 would cause too many problems. Instead, development went ahead using the 15 cm sFH 43, incorporating as many parts from the 15 cm sFH 18 as possible.
On April 3rd, 1943 Wa.Prüf 6 (the German organization in charge of military vehicles) stepped in and told Krupp they were only allowed to build a prototype of the Grille. On the 5th of May 1943, Krupp informed Wa.Prüf 6 that the February 8th order for two Heuschreckes had been canceled.
On the 21st of May, 1943, Maschinenfabrik Augsburg Nürnberg (M.A.N.), the company producing the Panther, was told to manufacture a complete set of suspension components, engine, transmission and drive train, as well as driver’s periscope and telescoping air intake for Krupp’s Grille prototype.
On June 7th, 1943, Krupp reported that a 1:10th scale mockup of the Grille would be ready by about mid-July, and a full-size prototype by the 1st of November. At an unknown date the 12.8 cm K 43 cannon was changed to a 12.8 cm K 44 L/55 with conventional breach; the 15 cm sFH 43 as well now had a conventional breech instead of a screw-type breach.
By the 20th of October, 1943, Krupp had failed to produce a prototype. Wa.Prüf 4 saw the project as going nowhere and ordered Krupp to stop all work on the project. Krupp did stop work on the Grille and Heuschrecke, but continued to design Panther-based weapons carriers.

Grille Design from January 18th, 1943 (Drawing Copyright Hilary Louis Doyle)

If at First You Don’t Succeed… – Selbstfahrlafette mit Absetzbarer 15 cm sFH 18

On January 20th, 1944, Krupp produced drawing SKA 879 for the Selbstfahrlafette mit Absetzbarer 15 cm sFH 18 (Self-propelled vehicle with dismountable 15 cm sFH 18). The vehicle was basically a normal Panther chassis with a wheelbase of 3,920mm; however, the rear of the hull was lengthened slightly to support a rear mounted artillery turret. The turret rested on a metal box; the turret and box forming the fighting compartment. Using metal beams apparently attached to the idler wheel, the entire assembly could be lifted up and off the vehicle by driving a few feet in reverse. Once off the chassis, the gun assembly could be used as a standalone artillery piece.
On February 3rd, 1943, Krupp presented a second design with drawing SKB 891. This version had the turret centrally mounted with the engine in the rear. The turret, which looks remarkably similar to that of the Heuschrecke 10, was lifted off over the front of the tank in the version 2, as opposed to over the rear as in the version 1. A wooden mockup of the Selbstfahrlafette mit Absetzbarer 15 cm sFH 18 version 2 was built, but neither design progressed past this point.

A conceptual model of the Selbstfahrlafette mit Absetzbarer 15 cm sFH 18, for unknown reasons, the chassis is not that of a Panther. Perhaps originally it was intended to use a custom chassis. This design has often been misidentified as the Heuschrecke 15.

Selbstfahrlafette mit Absetzbarer 15 cm sFH 18 Version 1 (Drawing Copyright Hilary Louis Doyle)

Selbstfahrlafette mit Absetzbarer 15 cm sFH 18 Version 2 Wooden Mockup

Skorpion of the Rhein – (Sfl.) Rheinmetall-Borsig

Like Krupp, Rheinmetall-Borsig also presented their first designs on the 1st of July, 1942. They were the 12.8 cm K 43 (Sfl.) Rheinmetall-Borsig (indexed Gerät 5-1213), and 15 cm sFH 43 (Sfl.) Rheinmetall-Borsig (indexed Gerät 5-1530). The vehicles were identical except for armament. Both had a 360-degree rotating turret and a hydraulic gun dismounting mechanism designed by Daimler-Benz, similar to that used on the Heuschrecke 10.
The 12.8 cm version was armed with a 12.8 cm K 43 L/51 with no muzzle brake. It fired a 28 kilogram projectile at 850 meters per second (2,789 ft/s), at a maximum range of 22 km (13.67 miles). The gun assembly for this version weighed 6.2 metric tons; the total weight of the vehicle was about 38 metric tons. The 15 cm version was armed with a 15 cm sFH 43 L/32.5; identical to the gun used on Krupp’s design except that Rheinmetall’s had no muzzle brake. The armament weighed 8.2 metric tons and consequently left the vehicle weighing 40 metric tons – 2 tons more than the 12.8 cm version. A prototype for each was expected to be ready by Summer 1943.
Rheinmetall’s design was seemingly met with little enthusiasm; Krupp’s Grille was the clear favorite. Despite the design not having been rejected, Rheinmetall chose to drop their original entry and proceed with another design.

12.8 cm K 43 Selbstfahrlafette Rheinmetall-Borsig – please note the end of the barrel has been cropped off in this image. (Drawing Copyright Hilary Louis Doyle)

15 cm sFH 43 Selbstfahrlafette Rheinmetall-Borsig (Drawing Copyright Hilary Louis Doyle)
On January 7th, 1943, Rheinmetall produced three more designs. In reality, these were the same vehicle, but with different armaments. The vehicles had centrally mounted, 360-degree rotating, dismountable turrets. The chassis was that of a Panther, extended to a wheelbase of 4,220mm.
Drawing H-SkB 80449 for 15 cm sFH 43 (Sfl.) Rheinmetall-Borsig
Drawing H-SkB 80450 for 12.8 cm K 43 (Sfl.) Rheinmetall-Borsig
Drawing H-SkB 80451 for 12.8 cm P 43 (Sfl.) Rheinmetall-Borsig
This version of the 15 cm sFH 43 (Sfl.) had a slightly longer gun barrel at L/34. It fired a 43.5 kilogram projectile at 600 meters per second (1,968.5 ft/s) up to 15 km (9.32 miles) range. The 12.8 cm P 43 was a high-performance (presumably) dedicated anti-tank gun. It fired a sub-caliber 14 kilogram (31 lb) shell at 1,175 meters per second (3,855 ft/s). Rheinmetall said they could have a prototype ready by the 1st of August if they received the needed Panther parts by the 1st of April, 1943. A wooden mockup was built of one of the 12.8 cm-armed versions, but this design did not advance any further.

12.8 cm K 43 Selbstfahrlafette Rheinmetall-Borsig – January 7th, 1943 (Drawing Copyright Hilary Louis Doyle)

12.8 cm Selbstfahrlafette Rheinmetall-Borsig – January 7th, 1943 Wooden Mockup
On or around the 24th of February, 1943, Rheinmetall’s entry for the Selbstfahrlafette für 12.8 cm K 43 und 15 cm sFH 43 Project was assigned the cover name “Skorpion”. This name probably covered the January 7th design, but since it is not known when Rheinmetall abandoned it, it cannot be said for certain.
Unwilling to stop perfecting the design, Rheinmetall continued to design more versions. On the 2nd of April 1943, they produced drawing H-SKA 81959 for the 12.8 cm Skorpion mit Panther Bauteilen; and on April 16th drawing H-SKA 82566 for 15 cm sFH 18 mit Panther Bauteilen. These designs had a Panther-based chassis with a wheelbase of 4,025mm. Around the 20th of October 1943, Wa.Prüf 4 canceled the Grille, Heuschrecke, and Skorpion projects.

12.8 cm Skorpion mit Panther Bauteilen – April 2nd, 1943 (Drawing Copyright Hilary Louis Doyle)

15 cm Skorpion mit Panther Bauteilen – April 16th, 1943 (Drawing Copyright Hilary Louis Doyle)

Not Done Yet – 15 cm sFH 18 auf Panther Bauteilen

Despite the Skorpion project being canceled, Rheinmetall continued to make more vehicle proposals in the early part of 1944. These final designs shared the modified Panther chassis developed for the Skorpion. Drawing H-SKA 86187 from the 11th of January, 1944 was yet another proposal for mounting the 15 cm sFH 18 on a Panther-based chassis. An improved version of this design came on January 31st with drawing H-SKA 88200. At some point, the mounting of the gun was raised from 2,500mm to 2,750mm off the ground to allow greater elevation. Further details are unknown.
It seems that after this, Rheinmetall-Borsig stopped all work on Panther-based weapons carriers. If they did take part in the design competition for the July 6th, 1944 requirement; the design has been lost. However, it is more likely they did not; leaving Krupp the only entry.

H-SKA 88200 (Drawing Copyright Hilary Louis Doyle)

Round Two – Mittelerer Waffenträger sFH 18 auf Panther

Please note that the dates for this section are contradictory. Panther & Its Variants gives the date of the issuing of the Geschützwagen Panther für sFH 18/4 (Sf) requirement as February 11th, 1944; while Panther Variants 1942-1945 gives it as July 6th. July seems to be the correct date; it also comes from the more recent book. Strangely, one sentence in Panther & Its Variants says that the Gerät 811 was based on “AZ 735 Wa.Prüf 4/Is from July 6th, 1944.” This would seem to indicate that the Gerät 811 was an entry for the July 6th requirement; perhaps the authors did not realize this at the time. Very little is known about the Gerät 811, apart from the fact it was armed with a 15 cm sFH 18/4. It is plausible that Krupp’s Mittelerer Waffenträger sFH 18 auf Panther was assigned the designation Gerät 811, but that is just conjecture.
On the 6th of July 1944, Wa.Prüf 4 put out the Geschützwagen Panther für sFH 18/4 (Sf) requirement: a request for designs for a vehicle based on the Panther. In near identical repetition of the events two years prior, the requirements were that the vehicle carries a 15cm gun in a dismountable turret that could rotate 360 degrees. The 15 cm sFH 18 cannon was required to have no muzzle brake, as it was supposed to be able to fire Sprenggranate 42 TS sabot rounds. Without the muzzle brake, the force of recoil of the cannon was a massive 28 metric tons; this was deemed acceptable for the chassis.
Krupp was the only company to show interest; on the 16th of September 1944, they unveiled drawing Bz 3423 for the Mittelerer Waffenträger sFH 18 auf Panther. It had a hexagonal, forward mounted turret on a lightly armored Panther chassis. The turret rested on a round pedestal within the tank. To remove the turret assembly, the turret was traversed 90 degrees to the left. The left side panel was folded down, forming two guide rails running perpendicular to the tank. At the end of each guide rail was a vertical spar, reinforced to one another with crossbeams. Roller blocks with two wheels each were affixed to either side of the turret and allowed it to be hoisted up, presumably by hand, onto the guide rails, where it was free to roll. Exactly how the turret was then moved off the tank is unclear. This whole process is described only in “Panther & Its Variants”, which states that two block and tackles were used to lift the turret. These would require some type of overhead gantry, which, if correct, raises the question as to why hoisting the turret assembly onto guide rails first is necessary at all. Presumably, the Panther was then driven away and the turret assembly lowered to the ground.
However the dismounting process was intended; once the turret assembly was on the ground four outriggers, which were otherwise stored fore and aft of the turret on the tank’s hull, were attached to it. Wa.Prüf 4 required that the number of outriggers be changed to three, as this would lower the gun’s overall height and give the gun crew easier access.
Shortly afterward, on the 21st of September 1944, Krupp produced a second version with the turret mounted centrally. Along with the second version, Krupp also proposed a version armed with the 12.8 cm K 44 L/55 (with muzzle brake). The 12.8 cm version’s turret was longer and slightly taller.

Mittelerer Waffenträger sFH 18 auf Panther Version 2 – 15 cm Version (Drawing Copyright Hilary Louis Doyle)

Mittelerer Waffenträger K 44 auf Panther Version 2 – 12.8 cm Version (Drawing Copyright Hilary Louis Doyle)
Only one day later, on the 22nd of September 1944, Krupp representative Dr. Bankwitz met with Wa.Prüf 4 in Berlin. Despite the requirement for a weapons carrier being only two months old, Wa.Prüf 4 ordered Krupp to stop all work on these designs, as they were no longer needed and the Panther chassis was no longer to be used for such purposes.

Never Give Up, Never Surrender

Completely ignoring Wa.Prüf 4’s demands, Krupp produced drawing Bz 3445 on October 12th, 1944 for the Mittelerer Waffenträger sFH 18 auf Panther (dünnwandig) (dünnwandig means “thin-walled”). This was a lighter version of the Mittelerer Waffenträger sFH 18 auf Panther. It had thinner armor, carried only 50 rounds of ammunition instead of 60, and had a redesigned, cylindrical turret. These changed saved 7 metric tons of weight.
On the 25th of October 1944, the High Command General of Artillery suggested doing away with the requirement for a dismountable, 360 degree traversing turret for possible future weapons carriers. However, this was deemed necessary and the suggestion was declined. On the 23rd of December 1944, General Wolfgang Thomale requested that the High Command General of Artillery hold off on issuing another panther-based weapons carrier requirement, as Panther production numbers were lower than expected. Instead, he requested that they wait to see if the role could be fulfilled by the upcoming 38(d) platform.
Due to the situation of the War in late 1944 and 1945, surviving information on the remaining projects is highly fragmented.
A Directive dated November 19th, 1944, ordered the cessation of the Gerät 808 project, a Panther-based weapon carrier for the 15 cm sFH 18/2, due to the plans not being ready.
A telex message dated February 6th, 1945, stated that the chassis without turret that Krupp required for the Schwerer Panzerhaubitze was waiting at the steel works in Hannover.
A February 20th, 1945 report on the emergency situation of the War gave a list of projects that were to be immediately terminated. On that list was a 15 cm sFH 18 auf Panther Bauteilen.

Sources

Special Panzer Variants: Development – Production – Operations – Hilary Louis Doyle and Walter J. Spielberger, 2007
Panther Variants 1942-1945 – Osprey New Vanguard, 1997
Panther & Its Variants – Walter J. Spielberger, 1993

Waffenträger 12.8 cm K 43 Selbstfahrlafette Krupp II/Grille 12
12.8 cm K 43 Selbstfahrlafette Krupp II/Grille 12 illustration by David Bocquelet

Waffentrager 12.8 cm Skorpion mit Panther Bauteilen
Waffentrager 12.8 cm Skorpion mit Panther Bauteilen by Jaroslav Janas


Mittelerer Waffenträger sFH 18 auf Panther Version 2 – 15 cm Version. Illustration by David Bocquelet and Alexe Pavel

Germans Tanks of ww2
Germans Tanks of ww2

Categories
WW2 Japanese prototypes

O-I

Japanese Armoured car Japan (1941-1943)
Super Heavy Tank – 1 built

Foreword

Hello, dear reader! Due to the constantly changing nature of this subject, this article has gone out of date. New discoveries have changed the story of the O-I significantly. A revised version of this article is in progress that will include translations of the original documents from Japanese into English. This is a very time-consuming process so please bear with us.

The O-I is a very obscure tank, with very little written on it and few original surviving documents. Even fewer documents can be accessed as they are owned by FineMolds, a private company in Japan. The information presented here has been cobbled together using surviving information to give the best possible assessment of the tank. This article does not incorporate the mountains of misinformation that have surfaced in recent years from rekindled interest in these tanks. Information for the developement the O-I leans heavily on Shigeo Otaka, who had first-hand knowledge of its development and has shared his story. However, it must be said that the recollections of an engineer do not implicitly reflect the entire historical truth, and could be distorted by time or other factors.

Go Big or Go Home

After Japan’s defeat at the Battle of Khalkhin Gol, the army realized its current tanks, the Type 97 Chi-Ha and Type 95 Ha-Go, were no longer competitive against the more modern tanks of the Red Army. Hideo Iwakuro, Chief of Army Affairs, instructed Colonel Murata, head of the 4th Technical Research Institute (an organization for tank development in Japan), to construct a super-heavy tank. Hideo Iwakuro’s exact words were “I want a huge tank built which can be used as a mobile pillbox in the wide-open plains of Manchuria; Top Secret…make the dimensions twice that of today’s tanks”. At the time of this request, the biggest tank in Japan was the modest Type 95 Heavy Tank. This leap in size from 26 tons to what would be over 100 tons worried Colonel Murata’s engineers, but each man kept their doubts to themselves.

The Mi-To Super Heavy Tank

Early Mi-To developmental logbook from Mitsubishi
Early Mi-To developmental logbook from Mitsubishi – Source
In March 1941, the initial design work was complete and the tank was ready to be built. The following month, select engineers, including Shigeo Otaka, were taken to the 4th Technical Research Institute’s Headquarters in Tokyo.  The engineers were told not to speak of what they would see and were guided through the dimly-lit barracks into a soundproof room with no windows, where they would later conduct meetings on the tank’s construction. The only entry to the room was a set of double doors (like an airlock), designed to protect the room’s secrecy from observers. Each officer present at the meeting had a separate piece of the design, that once assembled, revealed the whole tank. The tank’s name was Mi-To, for Mitsubishi, the company behind the construction and design, and the city of Tokyo.
Engineer Shigeo Otaka gave the tank’s parameters as 10 meters in length, 4.2 meters in width, and 4 meters in height (or 2.5 meters without the turret). The width of the tracks was 800 mm (although some sources state 900 mm). Propulsion would be provided by two Kawasaki Ha-9 air-cooled gasoline engines, placed parallel lengthwise in the hull, each producing 550 hp for a total of 1,100 hp.  The transmission was a scaled-up version of that used on the Type 97 Chi-Ha. It was mounted in the rear, between and behind the engines with five forward gears plus reverse. The suspension consisted of two coil spring bogies per side, each having two sets of four all-steel road wheels (four on the inside of the track teeth, four on the outside) for a total of eight pairs of road wheels per side.
The tank was armed with a Type 96 15 cm howitzer in the main turret. In front of the main turret were two mini-turrets, each having a 47 mm Type 1 Tank Gun. A fourth turret with dual Type 97 machine guns was placed above the transmission in the rear.  The armor was appropriate for a mobile bunker; 150 mm at the front, made by bolting an additional 75 mm plate to the tank’s 75 mm frontal hull. The side hull armor was only 35 mm thick, with an additional 35 mm side skirt covering the entire side and tracks.  On the inside, there was enough room for a man to stand comfortably. Two 16 mm bulkheads (other sources claim 20 mm) divided the tank into three sections, driver’s compartment, main turret fighting compartment, and engine compartment.

Construction

The following dates are not sourced. On April 14th, 1941, construction started on the Mi-To.  Colonel Murata’s plan was for construction to last only 3 months, however problems were found with the tank’s cooling system which delayed construction until January 1942. The hull was completed on January 8, 1942 while Mitsubishi manufactured the turrets. Unforeseen problems again delayed construction, and the tank would not be ready until a year later.
Budget table for improvements that could be made to the dive system. It is easy to tell that the Mi-To project was lacking funds as many of these proposals involve reusing old parts and manufacturing new parts from old materials in order to save money.
Budget table for improvements to the dive system. It is easy to tell that the Mi-To project was lacking funds as many of these proposals involve reusing old parts and manufacturing new parts from old materials to save money. – Source
For testing, the Mi-To was shipped to Sagami Armory (modern day Sagami General Depot) in Sagamihara, 51 km (31.7 miles) south of Tokyo. Only the people involved in the development of the tank participated in the transport, making it very difficult. In June 1943, the tank was disassembled for transport and covered with an awning to keep it hidden. Work on moving the tank started in at 2:00 am every day and lasted until dawn.  Transport took 10 days and it arrived at Sagami Armory at the end of June with tests scheduled for August 1, 1943.

Testing

About the time the Mi-To was completed and trials were scheduled, the Army assigned it the name O-I. Following Japanese tank nomenclature, I stands for “first”, and O for “Ooki-I-gou”, Japanese for “big”. This was the only time “O” was used as a tank type. While the Army’s designation was O-I, Mitsubishi’s internal designation continued to be Mi-To.
While it is not specifically recorded that tests were conducted on August 1st, this can be inferred from a fragmentary piece of evidence which states that the testing team ate lunch at 2:30 pm on August 1st. The O-I’s trials took place without the additional 75 mm bolt-on frontal armor and without the main turret, as the 35 mm roof plate was not ready. These exclusions meant the tank weighed only 96 tons. On the day of testing Colonel Murata was deployed at the front, so in his place for observation was Lieutenant Colonel Hidemitsu Nakano. Also present was the chief of Sagami Armory, Tomio Hara.
The testing grounds were the road and field north of the 4th Technical Research Institute’s building. The ground was soft during off-road portions of the tests and the O-I’s tracks sunk into the ground up to a meter. The tank tried to free itself, causing it to sink further and damage the suspension. Following the test, a full bow with both hands to the ground was made to the repair department chief.
O-I test driving schedule, August 1943
O-I test driving schedule, August 1943 – Source
After the tank was pulled out, tests continued on a concrete road, but because of the damage to the suspension the tank tore up the road and damaged its suspension further. The tests were abandoned and the tank was left and covered with a tarpaulin. The O-I was disassembled for scrap between August 3-8 of 1943, or more likely, in 1944. All that remains of the O-I is a single track link, measuring about 800 mm in width, and 300 mm in pitch. It was previously at Wakajishi Shrine but has since been moved to JGSDF Camp Takigahara.

Discrepancies

There was a post-war questioning with four Mitsubishi engineers who worked on the Mi-To, but the only one identified so far is Shinjo Masahisa. Unfortunately, these men did not have much to say about the O-I, and what they did say conflicts with proper sources. The only information they could provide was that the Mi-To had 100 mm of frontal armor, and could reach 40 km/h on roads. Both of these numbers seem incorrect as all other sources state the tank’s armor was 75+75mm and it had a top speed of 30 km/h and their higher claimed speed seems very optimistic for such a heavy tank.
Sagami Armory Chief, Tomio Hara reports the Mi-To as having a 10 cm (10 cm often refers to 105 mm in Japanese gun terminology) main gun, but blueprints show a short 150 mm howitzer. There is also an unverified claim of the tank’s size with a length of 10.1 meters, width of 4.8 meters, and height of 3.6 meters.
The dimensions of the track links are very unclear. One source states the tracks were 900 mm wide, another states 800 mm. Assuming the tank is 4.2 meters wide, then by comparing the hull to the tracks on blueprints, the tracks work out to 660 mm,  however this is too small for such a heavy tank. It is likely that the blueprints only show the run of the tracks, and not the complete width of the links themselves. The single surviving track link measures 800 mm wide, this would seem to be the correct number.
The blueprint’s cutaway side view of the frontal armor is clearly not 75 mm thick which has caused deliberation regarding if the armor on the blueprint is correct among the TankEncyclopedia team. It is likely that the blueprint only shows structural steel, as the Japanese often built tanks by constructing a 35 mm skeleton before welding on armor. However, the frontal towing hooks can be seen attached to this 35 mm plate on the blueprint and tow hooks are normally attached to the armor, not the structural steel. It is possible this was a mistake in the blueprints.

Surviving O-I blueprint
Surviving O-I blueprint – Source

Surviving O-I blueprint
Surviving O-I blueprint – Source

Surviving O-I blueprint
Surviving O-I blueprint – Source

Surviving O-I cutaway blueprint
Surviving O-I cutaway blueprint – Source

Surviving O-I cutaway blueprint
Surviving O-I cutaway blueprint – Source

Detailed view of the O-I's suspension
Detailed view of the O-I’s suspension – Source

O-I driver's periscope
O-I driver’s periscope – Source

Tow bar specifically made for the O-I
Tow bar specifically made for the O-I – Source

Surviving O-I track link
Surviving Mi-To track – Source

O-I specifications

Dimensions (L x W x H) 10 x 4.2 x 4 m (32.8 x 13.8 x 13.1 ft)
Total weight, battle ready 120+ tons
Crew 11 (driver, co-driver, commander, main turret gunner, 2x main turret loaders,
2x 47 mm turret operators, machine gun turret operator, radioman, engineer)
Propulsion 2x 550 hp Kawasaki Ha-9 air-cooled gasoline engines
Suspension Coil springs
Speed (road) 30 km/h (18.6 mph) (Probably an optimistic number)
Armament 150 mm (5.9 in) Type 96 howitzer
2x 47 mm (1.85 in) Type 1 tank guns
2x 7.7 mm (0.3 in) Type 97 heavy tank machine guns
Armor 75+75 mm (2.95 + 2.95 in) frontal armor
35+35 mm (1.38 + 1.38 in) side armor
Total production 1 incomplete prototype
For information about abbreviations check the Lexical Index

About the article

The Tanks Encyclopedia team has spent many hours debating internally about the O-I. Many different opinions were fielded and in the end we agreed to put it aside until more information was discovered. Recently, new information has come to light; which has led to a restructuring and improvement of the article.
Most older sources and representations of the O-I are now completely out of date. Both the 100 ton tank (sometimes called O-Ni even though this designation was never used), and the 140-150 ton O-I (sometimes called O-Ho) are known to be incorrect representations of the O-I. In recent years it was discovered that original documents of the O-I’s development survived the War. These documents were purchased by the model kit company FineMolds. FineMolds allowed people to see them, but only at FineMolds’ headquarters in Japan and to pay a considerable sum of money to access the documents. This led to many new claims regarding the O-I, but by those who would often refuse to reveal their sources, since they had spent money to acquire them. In late 2016 however, a Chinese author, Tang Qian, brought forward some of FineMolds’ documents in his own article and while it is not a complete set of documents, it does give us some proof and history of the O-I superheavy tank.

Sources

Tank and Tank Battles – Shigeo Otaka
Pacific War Secrets: All Japanese Secret Weapons, 2008
Imperial Japanese Army Land Weapon Guide, 1997
Japanese Tanks – Tomio Hara, 1978
Japanese Ground Cannons: Heavy Field Cannons – Sayama Jiro, 2012
The Japanese Superheavy Tanks on For the Record
The O-I on the Warthunder Forums
Finemolds Documents Brought to Light by Tang Qian


Tanks Encylopedia’s own illustration of the O-I

Categories
WW2 German prototypes

Gefechtsaufklärer Leopard (VK16.02)

Nazi Germany (1942)
Light tank – Mockup built

The Leopard that Never Prowled

The need for a small, fast scout tank in the Wehrmacht had long been overlooked. Light tanks and various armored cars had been pressed into this duty when needed. However an all new tank design was coming up, one that would defeat the heavily armored Soviet tanks such as the T-34 and KV-1. It was decided to develop a new scout tank based off of it.
Work was started on the Leopard by M.A.N. in mid 1941, paralleling the development of, and taking inspiration from, the Panther. At this time, M.A.N. had a contract to produce 5 experimental chassis. Blueprints for a wooden mockup were ready in November 1941. In January 1942, Wa.Prüf. 6 (the governing body for tank development) decided to turn detailed design work on the chassis of the Leopard over to MIAG, and the turret to Daimler-Benz. This would allow M.A.N. to focus work on the Panther, which was needed on the Eastern Front as soon as possible.
It is worthy of note that even before the winning design for the Panther was chosen, work had already been started on the Leopard. Daimler-Benz was developing their own version based on their VK30.02(DB) when M.A.N.’s design was chosen. How far Daimler-Benz’s design was developed, or how it may have looked, is not known.
The VK16.02 was based on experience gathered with its closest relative, the VK16.01, also known as the Panzer II Ausf.J. However, the two tanks are very much dissonant, with the Panzer II Ausf.J being more like the British infantry tank Matilda than a scout tank.

The Fuhrer’s Meddling

By the end of May, 1942, a full size wooden mockup had been built. Preliminary designs were shown to Hitler in March of 1942. At this time, he was given the following projections: Design work was to be complete by the end of October, and production was to start in April of 1943. Production was to total 105 tanks by the end of 1943, with 150 more in the spring of 1944. On June 4th, 1942, Hitler was again shown designs for the Leopard; a lighter, faster, 18 ton version, and a heavier, and more thickly armored, 26 ton version. He picked the heavier design, opting for increased fordability and heavier armor, while rejecting the idea that 26 tons was too much for small bridges. On July 27th, 1942, MIAG presented Wa.Prüf. 6 with design FKo 252, for the Gefechtsaufklärer Leopard.
The tank had 50 mm (1.97 in) of frontal armor set back at 50 degrees. Side and rear armor was 30 mm (1.18 in), with deck and belly armor of 16 mm (0.63 in). Armament consisted of a 5 cm (1.97 in) KwK 39 L/60, and a single 7.92 mm (0.31 in) MG 42. It was crewed by four men: a driver, a commander, a gunner, and a loader who was also the radio operator. Propulsion was provided by a Maybach HL 157 P engine putting out 550 hp at 3,600 rpm, driving a Maybach OG 55 11 77 semi-automatic gearbox with 8 forward, and one reverse gear. In common with most German tanks, the transmission was at the front. Communication between the crew was done by intercom, and with other tanks by a FuG 2 radio; or a FuG 5 and FuG 7 for command tanks.
In September 1942, production plans for the Leopard were as follows: 1 in April 1943, 3 in May, 5 in June, 7 in July, 11 in August, 18 in September, with production leveling out at 20 per month in October, 1943. At the same time, Hitler had ordered production of 150 tanks per month, as well as all work on the lighter, 18 ton version to be dropped. Albert Speer met with Hitler on October 13th, 1942, to discuss tanks. Speer informed Hitler that troops unanimously preferred the 18 ton design over the 26 ton design. Speer also pointed out that the 26 ton Leopard was barely different from the Panther, and at that point why wouldn’t they just use the Panther as a basis for a scout vehicle. Hitler agreed that the 18 ton (which at this point was already 22 tons) Leopard could be produced, as long as the role of heavy scout tank could be filled with a Panther variant. On January 3rd, 1943, Hitler decided the Leopard would be dropped, as its armor and armament did not meet specifications that would arise in 1944.
Aufklarungspanzer Panther - Credits: Panzer Tracts 20-2
Aufklarungspanzer Panther – Source: Panzer Tracts 20-2

Leopard’s Legacy

The Panther-based scout vehicle, known as the Aufklärungspanzer Panther, never made it past the design phase. For the rest of the war the only dedicated scout tank to be produced was the Panzer II Ausf.L Luchs, though this was still seen as a stop-gap design. The only physical contribution that came of the Leopard design was the turret; it appears a modified version of Daimler-Benz’s Leopard turret was used on the Sd.Kfz.234/2 Puma armored car. Although there is no documentation to back up that fact, the Puma’s turret is nearly identical to the Leopard’s turret; the only difference being the sides of the turret on the Puma were angled at 20 degrees, compared to the Leopard’s 30.

Variants

Two vehicles were based on the Leopard’s chassis, a Waffenträger (weapon carrier) and a tank destroyer. Hardly anything is known about ether of them.
The 10,5cm LeFH Waffenträger auf Leopard was designed by Rheinmetall. Only a wooden mockup was built.
The Sturmgeschutz Leopard tank destroyer was designed in the autumn of 1942; it was armed with the Panther’s 7,5cm KwK 42 L/70.
Both projects were canceled when the Leopard was dropped.

An article by Harold Biondo

VK 16.02 Leopard specifications

Dimensions (L-W-H) 4.74 x 3.1 x 2.6 m (14.7 x 10.2 x 8.6 ft)
Total weight, battle ready 21.9 Metric tons
Armament 5cm (1.97 in) KwK 39 L/60 with 50 rounds
7.92 mm (0.31 in) MG 42 with 2400 rounds
Armor 16mm to 50mm (0.63 in to 1.97 in)
Crew 4 (driver, commander, gunner, radio operator/loader)
Propulsion Maybach HL 157 P, 550 hp (410 kW)
Speed 60 kph (37 mph) maximum speed, 45 kph (28 mph) realistic top speed
Suspension Torsion bar
Estimated range 500 km (311 mi) on road, 300 km (186 mi) off road
Status 1 wooden mockup

Sources

German Armored Rarities 1935-1945 (Schiffer)
Panzer Tracts 20-2
Encyclopedia of German Tanks of WW2 revised edition

A Gefechtsaufklärer Leopard in a fictional livery, as it might have appeared, had it gone into service in 1944
A Gefechtsaufklärer Leopard in a fictional livery, as it might have appeared, had it gone into service in 1944

Vk 16.02 MAN
by Giganaut

Three way view - Source: Panzer Tracts 20-2
Three way view – Source: Panzer Tracts 20-2
10,5cm leFH Waffentrager auf VK16.02 Leopard
10,5cm leFH Waffentrager auf VK16.02 Leopard Source
Around the internet this tank is claimed to be the Leopard; it is not. These photos are of a Panzer II Ausf.L Luchs variant
Around the internet this tank is claimed to be the Leopard; it is not. These photos are of Panzer II Ausf.L Luchs V29, which was modified with a wooden superstructure and Praga diesel engine. Source
Originally published on August 21, 2016
Germans Tanks of ww2
Germans Tanks of ww2