Hello everyone,

following is the account of all we know about the Czechoslovak hightier TVP project, at least the rough outline. It is clear that proper research into this will take more time, but we’ll get there.

Summary

The development of post-war Czechoslovak tanks started very soon – by the end of 1945, where VTÚ (Vojenský Technický Ústav – Military Technical Institute) filed a report to MNO (Ministry of National Defense) and to the local Red Army committee on the state of current tanks and other armored vehicles development. This led to series of proposals I will deal with later, culminating with the TVP project (Tank Všeobecného Použití – Tank for General Use). TVP was heavily influenced by both Soviet (cast turret) and German development (gun mount, welded turret version, mantlet) and drew from the best of both worlds.

1945-1946 specifications and first Škoda proposal

Based on the abovementioned report, on 17.10.1945, the 1st Department of Army HQ submitted its ideas about the new medium tank to VTU. The requirements included:

- 30-33 ton weight
- 5 man crew
- 8,5 to 10,5 cm gun with 80 shells and with a coaxial Vz.37 or BESA heavy machinegun, with another MG of the same type used as bow machinegun (3600 rounds for both MG’s)
- armor plates – RHA plates of following thicknesses: 65mm, 40mm, 30mm and 20mm
- 450mm clearance
- ground pressure of 0,5kg/cm3
- a diesel engine
- road speed of 50 km/h

Interesting fact is that the vehicle design itself was to be selected only after selecting the gun itself (the tank was supposed to be “built around the gun”), based on comparison trials of all the guns available. In December 1945 to February 1946 (Dubánek here mixes the dates, an obvious typo – I fixed it), the VTU representatives considered the 88mm German AA gun (the AA role is specifically mentioned, but it’s possible the author has the KwK 43 L/71 in mind – in post-war Czechoslovakia, the PaK 43 and 41/43 were adopted due to the lack of native or Soviet AT guns as PTK vz.43 (protitankový kanon – AT gun, vz.43 – 1943 pattern) with shell velocity of 1000 m/s or a 105mm gun (900 m/s) to be viable, as during tests, both were able to penetrate 100mm of armor at 3000 meters (60 deg – means 30 deg using German angle methodology, at that point Czechoslovak army was using the German trial methods, unlike the pre-war ones, that were very obscure).

Second department of III.section of VTU introduced on 1.3.1946 their preliminary project of a medium tank with a model of 1:50 scale, called the TVP (Tank Všeobecného Použití).

It was a classic Czechoslovak tank school concept. The hull shape resembled the one of LT-38 and it still had leaf springs. The mantlet shape was influenced by German tanks, the driver and radioman hatches were actually inspired by British designs. The Soviet inspiration was in the electrical propulsion of the turret rotator. This first version also had a hull flamethrower, linked to the bow machinegun (Vz.37 or BESA). It was considered to implement an automatic loading mechanism by Škoda (37mm, 47mm and 57mm versions existed), but at that point it was decided semi-automatic breech would be sufficient. The coaxial machinegun was to be linked to the gun within the gun mount in order to save space in the turret. Commander’s copula was recommended to be made fully traversable with 5 episcopes attached to the traversing ceiling, along with commander’s binoculars or artillery binocular sights and was to be equipped with holes for emeregency signal flags. The turret was also proposed to be equipped with a roof-mounted grenade launcher/mortar for close defense (5-20 meters).

The bow machinegun (and the flamer) were capable of -10 to +25 elevation thanks to the mount, similiar to the LT-38 tank. The flamethrower was to be fuelled by a 100 liter napalm tank (not technically napalm, Czechoslovaks developed their own flamethrower fuel of excellent properties, might get into that if necessery) – this tank would prolong the hull only by cca 25 cm. The vehicle was to be equipped with a smoking device and by additional side armor (“Schurzen style” – another German lesson) consisting of steel mesh, fixed at 20 cm from the main hull. This mesh armor was trialed as early as 1945.

The mobility was to be ensured by an unspecified diesel air-cooled engine, providing the vehicle with power-to-weight ratio of 20 horsepower/ton (interestingly, the ratio was specified, not engine type or horsepower, given the fact the tank was proposed to weight 33 tons, the engine would have to have 660 horsepower). Ground pressure was not to exceed 0,5 kg/cm3. The design counted on leaf springs for suspension, which was clearly a weakness the designers realized. The commander of VTU, Col. Ing. Josef Trejbal proposed at least two prototypes to be built by each of the design competitiors (realistically, only Škoda and Praga were available). Each of the prototypes was to be built without the gun first.

Škoda reacted on these VTU demands first with its proposal from 8.12.1946 (archive drawing designation Am 39-P), which was considered to be the “factory” version of the theoretical VTU TVP design. Between 1947 and 1948, the conditions of the project were being “chiseled”, including the final version of army demands (that were always in the flux). There is very little known about the TVP project from this era. Czech historian Oto Holub (Československé tanky a tankisté, 1980) claims that in 1948, Škoda was working on a “medium TVP tank” weighing 16 tons with a 75mm gun, powered by a Škoda 147,2kW (197hp) engine with Praga Wilson transmission and 3-man crew, but it is widely believed (Dubánek et. al.) that Holub simply mixed up the Škoda T-17 light tank project with TVP. Holub also mentions a “heavy” version of TVP tank (which most likely would be the TVP we are talking about) of following parameters: 30 tons, 75mm frontal armor (40mm sides), armed with a (German) 105mm gun (900 m/s), powered by an unspecified Škoda 454 kW engine (609 hp), Praga Wilson transmission and 50km/h maximum speed.

As for the guns used for this early project, two are mentioned. First is the 105mm gun (apparently of German origin) with 900 m/s velocity, which would correspond to the German 105mm FlaK 38/39 (881 m/s) of which 200 or so were made and some where most certainly left on Czech territory after the war was over. The Czechoslovak army officially adopted the type into service after the war with the designation of 105 mm PLK vz.39N (PLK = Protiletadlový Kanon, AA gun – vz.39 = vzor 1939, 1939 pattern and N = německý, “German”), on 1.2.1949 the army had 24 of them in service, on 1.4.1960, 16 were still in service officially.

The gun had following characteristics, according to US Catalog of Enemy Ordnance:

Caliber: 105mm
Barrel length: L/52,8
Shell velocity of HE shell: 880 m/s
Shell velocity of AP shell: 860 m/s
Weight of HE shell: 26 kg
Weight of AP shell: 26,1 kg
Capable of firing an APC shell of following penetration:

165,1 mm at 1000 yards (914 meters)
152,4 mm at 1500 yards (1371,6 meters)
142,2 mm at 2000 yards (1828,8 meters)

Further research into this type of shell is possible.

Another gun mentioned by M.Dubánek was the 75mm A26 autoloaded gun with a drum loading mechanism, trialed in Czechoslovakia on a Tiger I testbed tank in 1947. There is some sort of mix-up regarding what this gun actually is. It is clear that there were both the A18 and A26 Škoda projects in existence, but I.Pejčoch (obrněná technika) mentions the A18 75mm gun (for Škoda T-25) trialed on the Tiger in 1947 – with a drum autoloader too. For the T-17 light tank project, Dubánek mentions the 75mm A18. Dubánek himself admits (page 170) that the times were turbulent and many documents simply “got it wrong”. Given the fact that in 1945 according to all sources the 75mm caliber gun was considered insufficient (and thus was not developed further after 1945), I am inclined to believe that in this case, the A26 and A18 on Tiger are one and the same gun. In such a case, the gun would have following parameters:

A18/26
Caliber: 75mm
Barrel length: L/55 (4310 mm)
Shell type: probably specific Czechoslovak test shell (“vzor 1943″)
Shell velocity: 900 m/s
Shell weight: 6kg
Penetration: 90mm (60 degrees) at 1000m
Factory rate of fire: 15 rounds per minute (Dubánek however mentions 40 rounds per minute for the A26 variant, trialed on the Tiger)
Gun weight, including autoloader: 1600kg

The penetration at 1000 meters is the only real data we have on its penetration. 90mm at 60 degrees (almost certain to be 60 degrees, as Czechoslovak army used German methodology during the war) means cca 104mm at 90 degrees. Based on PaK 40 L/48 and PaK 42 L/70 examples, the loss of penetration between 100m and 1000m is roughly 20 percent, which would give us solid penetration of 130mm at 100m. The capacity of the autoloading mechanism is however not known to any of the Czech sources. Given the fact that proposed tier 6 T-25 would use this gun too, it gives us a nice continuation possibility.

If needed, three more guns could be considered. All three were paper designs from 18.3.1947 – these three Škoda proposals were: 76,2mm L/49 (6,58kg shell, 840 m/s), 76,2mm L/66,5 (6,58kg shell, 1000 m/s) and 88mm L/66 (10,2kg shell, 1000 m/s). The 88mm project was scrapped on 10.6.1947 (76,2mm caliber was decided to be sufficient) and the development of the other two led to the development of the A19 AT gun (76,2mm L/70, 6,4kg Soviet AP shell in a longer casing, 915 m/s velocity). The A19 gun was subsequently improved to L/72, muzzle velocity was increased to 925 m/s, Dubánek mentions the use of a (Soviet) 76,2mm subcaliber shell. A prototype was made (firing trials were successful) and the development continued until 1951, when the gun was rebored to 85mm (or, rather, Vz.44S (S-53) 85mm gun barrel was used), resulting in the creation of 85mm Vz. 52 cannon, but that’s already irrelevant. The original A19 prototype exists physically in Lešany tank museum.

By 1948, (now nationalized) Škoda was ordered to actually deal with the project, since the chassis was proposed to be used for several SPG and TD project (this was ordered by the DKS (artillery committee – a panel of ministry of defense and Škoda artillery experts) on a meeting, held from 18.11.1948 to 20.11.1948.

Summary:
Crew: 5
Dimensions (VTU proposal):

Length: 6560mm (8978mm with barrel)
Width: 3280mm
Height: 2043mm (2367mm with copula)
Clearance: 537mm

Škoda proposal:

Length: 6429mm (8980mm with barrel)
Width: 3265mm
Height: 2041mm (2347mm with copula)
Clearance: 510mm

Armor: 65mm (75mm for Škoda) frontal upper plate and front turret plate, 40mm sides, 30mm rear, 20mm roof and bottom
Gun: see above (75mm A18, 105mm FlaK 38/39, 76,2mm A19, two 76,2 and one 88 proposals)
Maximum speed: 50 km/h
Engine: unspecified – 600 or 609hp diesel
Transmission: Praga-Wilson
Suspension: leaf springs
Ground pressure: 0,5kg/cm3

T-50 and T-51

Based on the preliminary works mentioned above from January 1948, in January 1949, the HQ of the army issued an official request for a tank project to Škoda and Praga. For Škoda, the project had designation T-50 (task 181 B), for ČKD (Praga), the designation was T-51 (task 181 A). The original proposed weight of 35 tons was later increased to 40 tons. Upgunning was also needed and the caliber picked for the final version of the official demand was 100mm (the shell velocity was specified at 845 m/s, the vehicle was to carry 60 to 70 rounds). Further demands included sufficient protection while keeping excellent mobility on the battlefield, air-cooled diesel engine capable of operating under all climatic conditions. Maximum length was set to 6500mm, maximum width was set to 3200mm and maximum height to 2800mm, clearance was to be 500mm. Frontal armor was to be 65mm thick, sides and rear 40mm and everything else 20 to 30mm. The hull was to be welded. Secondary armament was to be a new 12,7mm AA machinegun (apparently Soviet DshkM) with 1000 rounds a hull-mounted 7,62mm machinegun and a coaxial 7,62mm machinegun (both were supposed to be newly designed Czechoslovak machineguns with 3600 rounds for both). According to the plan from 1949, the preliminary project was to be approved until 21.8.1949, by the end of 1950 the prototype assembly drawings were supposed to be ready and on 1.3.1950, the first prototype parts production was to be initiated. The entire development was to be ready in June 1952.

The VTU oversight of the Škoda project was performed by Maj.Ing.Jan Hajšman and of the ČKD project by Cpt.Ing.Albín Třešňák. During the development, other preliminary projects based on TVP chassis were added, such as the TVP ARV, bridgelayer tank, flame tank and mineclearing TVP with dozer blade. The development of most of these project however was not even started.

On 27.1.1949 the preliminary project from Škoda and Praga were ordered. Škoda was to present a tank and cannon drawings and create a 1:1 wooden mockup until 30.9.1949 (ČKD had the same deadline). Apparently, Škoda met the deadline with its T-50 project and presented the entire project in September 1949, including wooden mock-up, but the vehicle was criticized by the attending military staff for tactical reasons: the soldiers complained that the tank is too tall and probably too heavy too. After five meetings held in Pilsen (Škoda) and Prague (MNO), the project was rejected. On 24.11., new proposal was presented and on 2.12.1949, 1:10 mockup of this new variant was created. This variant had a “pike nose”, much like the IS-3, but only a day later (3.12.1949), the soldiers rejected this feature. For drawings of this model, an archive visit is most likely necessery.

The T-51 was even more “mysterious” and the researchers have not found any drawings of this model to work with and very little is known apart from the fact that it had one less roadwheel and didn’t have the pike nose. In the absence of any hard data, the only thing we have is the set of requirements and the hints above. One thing is for certain: by the end of 1949, both the T-50 and T-51 project were united into the T-50/51 project.

T-50/51

Former competitors were (because of the orders from ministry of defence) now working together as allies. Both companies were to present their “own” T-50/51 prototypes, the difference between which was mainly the engine used. By the end of 1949, a coordination office was created in order to support the cooperation. However, the differences between former projects (apparently there were some serious ones) led to the fact that the development was basically started from scratch as proven by the fact that during one of the first coordination office meetings on 14.1.1950, the basic specifications were discussed: 35-40 tons. The army requested the speed of 60 km/h, but Ing.Surin of Praga (possibly the most famous Czechoslovak tank designer ever, responsible for the LT-38 for example) stated that this request is unrealistic. On 16.1.1950, the hull shape and engine compartment size were agreed upon and unified. Škoda recieved a permission to work on a new type of turret (cast one) as well as on the new 100mm tank gun in two variants (designated AK1, that was developed along with the 100mm R11 and 100mm A20 – the development of those two started however earlier – end of 1948).

The AK1 was ambitious: It was to be a 100mm L/55 (5500mm barrel length) gun, capable of firing a 14,75kg shell at 900 m/s. The second variant of AK1 was L/53 (or rather 52,7, as the barrel was 5270mm long) with the shell velocity of 890 m/s.

On 23.1. and 24.1.1950, it was decided for the ČKD X-shaped diesel engine to be used. Around this time, Ing.Suring was informally selected as the leader of the entire project because of his contributions. He started working in Škoda on 6.2.1950 in order to get the work going. He is the author of the drawings of the vehicle. Two variants were considered: both had the same hull and cast turret, but one had an H-shaped engine and the other had an X-shaped engine. Surin had only 14 days actually to come up with the drawings – he immediately requested the turret to be made lower (sleeker) – as a result, on 10.2.1950, Ing. Zíka from Škoda presented two drawings with the lower turret (only 800mm tall), including 1:10 wooden mockups. Both options had different mantlets – from front, one was oval-shaped (German style) and one was triangle shaped (apparently, the latter was selected).

By the end of January, the shape of the hull was also discussed, including the number of roadwheels (ČKD had 5 pairs, Škoda had 6 pairs). Apparently, the 6-pair solution was adopted after some pressure from military liaison Maj.Hajšman. It was also decided that one entire prototype hull from armor steel would be produced by VŽKG (Vítkovice steelworks), while three more hulls from regular steel would be produced by Škoda. Škoda and ČKD would then cooperate on further development, while the turret would be developed exclusively by Škoda. Each company would then independently develop the engine, the transmission, drivetrain, steering mechanism, pedals, seats, fuel tanks and engine access ports. Engine air filters were to be developed by ČKD, while Škoda was to develop the suspension, ventilation and electric wiring. Furthermore, both companies were tasked with solving the implementation of the Soviet V-2 engine as a stopgap measure, because the high-power diesels still remained only on paper. What it meant in total was that Škoda would do most of the work, because ČKD was tasked also with the development of the universal LP chassis (light chassis for light tank/light tank destroyer/light SPG use).

On 15.2.1950, the number of planned prototypes was reduced to three (two from soft steel, one from armor steel). Furthermore, each company was to build two prototypes of their engines (Škoda – 16 cylinder AHK, ČKD – 16 cylinder AXK) with transmissions and ČKD was to solve the issue of implementing the Soviet V-2 engine. TVP transmission was actually built and tested in 1949 on a T-34/85 tank (as a part of the T-34/85 upgrade program) and the results were promising. The suspension was now planned to be a torsion bar one, but there were problems with their manufacture. Even though ČKD was developing their own engine air filters, Škoda came up with a plan to use captured Panther air filters. ČKD in turn came up with a proposal to use hydraulic gun elevation control and Ing.Surin came with a plan to introduce a mechanical automatic loader, but both plans were declined by the military representatives.

The key date for development was 27.2.1950, when a meeting took place at Czechoslovak tank army HQ. The committee that assembled approved the final version of the TVP project (based on unified drawings Am 634-P and Am 635-P), which however lacked specific details. Both drawings were actually made earlier (18.2.1950) and the Praga one bears the name of “TNH tA”. These drawings are however missing the assumed bow machinegun and the driver’s hatch. This is how it looked:

T-50/51 was also compared to the T-34/85 tank (that was still in service) and came out favourably. The 100mm gun was able to penetrate 140mm of armor (60 deg) at 1000m and the vehicle was supposed to have superior maneuverability, given the 1000 horsepower AHK/AXK engine and better suspension. However, it was also heavier than the T-34/85. It was also considered for frontal and rear parts of the hull to be cast instead of welded and General František Papoušek was interested in the automatic loading mechanism. The meeting also confirmed previous production distribution and plans and both companies promised to deliver soft steel prototypes until 30.4.1952 (plus the armor steel prototype until 31.12.1952). However, even in 1950 it was clear that neither Škoda nor ČKD would have mass production capabilities (especially given the fact that the ambitious plan counted on mass production after 16 to 22 months from the prototype introduction). Major Hajšman also assumed the full documentation of the tank could be sent to USSR for assessment in November 1950.

Czechoslovakia obtained the license to produce the T-34/85 in 1949, but it still did not prevent the military from hoping that during the 2nd 5-year plan (1953-1958), Czechoslovakia would produce 1799 pieces. That however was just fantasy. Insufficient production capacities (T-34/85 production ran from 1951) and political pressure from USSR caused the project to be abandoned very early. On 4.3.1950 a meeting took place, where the decision of the Minister of Defense to stop the T-50/51 development was announced. The engine itself was to be further developed and the armor development also ran for a while after. The development was entirely cancelled by the decision No. 15705 sometimes later in 1950, including the development of all TVP-based projects (tank destroyers, SPG’s). All the production capacity was in the meanwhile used for the T-34/85 and in 1955, the first T-54 arrived in Czechoslovakia as a precursor to full-fledged license production, that ran practically until 1981 in one form or another.

100mm guns

Here, basically we have two options: the A20 and the AK1

The “historical” gun for the TVP medium tank was the AK1, described above

AK1
Caliber: 100mm
Barrel length: L/55 (5500 mm)
Shell type: Czechoslovak Vz.49 shell (newly developed) or Soviet 100mm shells for D-10T (a requirement for caliber unification)
Shell velocity: 900 m/s
Shell weight: 14,75 kg
Penetration: 140mm (60 degrees) at 1000m
Rate of Fire: formally 25 rounds per minute

As you can see, the performance of this gun is not exactly stellar. 140mm at 60 degrees gives us cca 162mm at 90 degrees at 1000 meters. If we take the penetration loss for D-10T (which is roughly 22 percent), it gives us cca 198mm penetration at 100 meters. There are several ways how to improve it however. First is the proposed autoloading device. There were functional Škoda autoloaders developed, so this is not just fantasy. However, no further parameters are known. Second way is using Soviet subcaliber and HEAT ammunition for 100mm guns, which would give us roughly the performance of Soviet 100mm guns of tier 9 and 10.

There is however a second option. Along with AK1, its’s “big brother”, the A20 AT gun was developed (along with the 100mm R-11 AA gun). Both the A20 and R11 were developed from July 1948 by Škoda. One of the demands from the Ministry of Defense for this gun was high rate of fire (25 rounds per minute for at least 7,5 minutes) and high penetration (160mm at 60 degrees at 1000m – in WoT terms that’s probably like 225-230mm penetration using the same formula as above). The unification with Soviet shots was considered as early as 1948 and in October 1950, Soviet “advisors” even asked for the weapon plans, because they thought they could use that for Soviet Union as well. The final decision to unify the ammunition happened in 1952 (apart from the R11 version, where Soviet ammunition proved inferior). The development of the AA gun ran until like 1957 when it was finally cancelled.

A20
Caliber: 100mm
Barrel length: L/65 (6470 mm)
Shell type: Czechoslovak Vz.49 shell (newly developed) or Soviet 100mm shells (a requirement for caliber unification)
Shell velocity: 940 m/s
Shell weight: 14,75 kg
Penetration: 160mm (60 degrees) at 1000m
Rate of Fire: formally 25 rounds per minute

The AA version had a tray autoloader implemented. While the original 5 round one is possibly too large, a 3 round autoloader would probably fit inside some closed space. The A20 gun was later modified and accepted in service under the designation of 100mm Vz.53. The gun itself is semi-automatic with wedge breech, firing a 14,74kg AP shell at 955 m/s, barrel length is L/64 (6407mm without muzzle brake), cca 600 were made between 1956 and 1960. Of course, this is too late for the TVP.

T-50/51 dimensions

Length: 6362mm
Width: 3019mm
Height: 2043mm
Turret height: 789mm
Clearance: 464mm
Roadwheel diameter: 929mm
Track width: cca 600mm

Crew: 4-5 (depending on autoloader)

Armor (based on latest drawing measurements):

Turret: front cca 112mm, sides and rear 84mm
Mantlet: near the gun 306mm, otherwise 93mm
Upper frontal plate: 93mm at 30 degrees from horizontal = 186mm EFF
Lower frontal plate: 84mm at 45 degrees from horizontal = 119mm EFF
Hull sides: 75mm

Weight: 40 tons
Speed: 50-60 km/h
Engine: 986hp (1000hp) 16-cylinder AHK or AXK diesel or 493,5hp V-2-34 diesel from T-34/85
Power-to-weight: 25 hp/t (or 12,33 hp/t with V-2-34)