The ST vz. 39 also known as the V-8-H was a medium tank developed by CKD during the late 1930’s and like many of the Czechoslovakian medium tanks being developed never got out from the prototype stages of development. Like many of the earlier Czech attempts to create a medium tank the project would be plagued with many issues in particular the engine which had been apparent on earlier Škoda and Tatra designs during the early and mid 1930’s.
Development of the CKD V-8-H would start in October 1936 around the same time Škoda and Praga were working on the ŠP-II-b another prototype medium which would eventually evolve into the Hungarian Turan series of tanks. Cooperation between Czechoslovakian companies was high in the 1930’s with many of these projects sharing components and designs leading to a quick development with the first prototype being ready and conducting factory tests in the summer of 1937. Tests with the military were supposed to be conducted in December 1937 in Milovice however according to both CKD and army officials no such tests took place.
Blueprints of the V-8-H as originally intended.
Like with the majority of Czechoslovakian medium tanks the tank would have 143 listed failures by February 1938, 16 of which were serious in nature with the biggest problem being the Praga NR engine which was powerful but not yet tuned. The undercarriage was another major issue with the rubber bandings of the support wheels constantly falling off which would result in a major rebuild of the tank in March 1938 to try and alleviate these issues. Rigorous testing would continue with the new reconstruction of the vehicle with test drivers praising it’s easy handling and not to demanding maintenance however the testing committee were still not satisfied with the vehicle. The committee had proposed several changes to the design before interruptions in April 1938 with the concerns for the vehicle being on the shape of the hull which mainly concerned the new curved front wall regarding it’s fighting compartment and machinegun placement.
Around April 1938 the tank had finally received a complete turret armed with the 47mm Škoda A11 cannon and a ZB-53 machinegun whilst the engine cooling and gear box had received minor changes with the reconstructions finishing by May 1938 and would continue to do tests until August 1938 were the tank would be send to the factory to replace the transmission with a transmission that had better distributions of speed. From January to August 1938 the tank had travelled 12735m, 5473 of which had been in difficult terrain. Around August of 1938 the vehicle would be selected for a production run of 300 vehicles to be produced by February 1940 of which CKD would be tasked to produce 95 whilst Škoda the other 205 mainly down to CKD’s production run of the very successful LT vz. 38 (Pz 38(t)). It was mainly chosen as despite the committee who deemed the tank not mature enough yet it was the only medium tank of it’s category in the state to begin a production run as medium tanks such as the Škoda T-21 were not ready yet. Like with the LT vz. 38 though the cost for the vehicle from the demands of army was an expected 998,000 crowns a piece however CKD demanded 1,250,000 for each fully equipped tank with the eventuality of the production being agreed upon alongside a further 150 vehicles.
With the Munich Agreement happening in late September 1938 the order for all 450 vehicles was cancelled but the tank would continue to be tested until mid November 1938 were it would be accepted into the army as the ST vz. 39 or Medium Tank model 39. CKD would not take the offer to increase the attractiveness of the vehicle to foreign markets for a commission of 5% and would try to offer the vehicle on the export market on the 21st of November 1938 under it’s factory name.
Germany would occupy the rest of Czechoslovakia by 1939 and the vehicle would be tested at Eisenach where an order for a second prototype would be placed in November 1939 this vehicle however would have a concrete block placed to simulate the load instead of a turret being referred to as V-8-H II or V-8-Hz. Despite the Wehrmacht buying this vehicle because of the Panzer III’s similar technical parameters there was no question of equipping the tank with a stronger German armament. The V-8-H alongside the R-2a and T-21 tanks would all be demonstrated in Romania with the tests showing favours to all three tanks at different points with the eventuality of the T-21 being chosen for production as the R-3. The tank would also be demonstrated to Italy, Sweden, China and the Soviet Union but proved unsuccessful due to the costs. Out of these Sweden was the closest to buying the vheicle however in the end had chosen the Landsverk Strv m/42. Finally the last serious customer Turkey had shown inrest into the vehicle on the requirements that it would be equipped with the 37mm Škoda A7 cannon from the LT vz. 38 but would be cancelled down to various circumstances and relationships.
Blueprints presented of the V-8-Hsv to Sweden
Both prototypes would be demonstrated to Czechoslovakia again after the war and were eventually scrapped.
The crew of the tank consisted of 4 with the driver sitting on the right side whilst the radio operator on the left of the front each with a 50mm bulletproof glass window whilst the commander and gunner sat on a bicycle seas suspended by metal tubes. The commander had access to a small turret that could fully rotate to view from. The guns had 2.6x magnification scopes.
Dimensions (L-W-H): 5.35m x 2.27m x 2.34m (17’6’’ x 7’4’’ x 7’7’’ ft)
Total Weight: 16.2 tons
Crew: 4 (Driver, Radio Operator, Gunner, Commander)
Propulsion: 8 cylinder Praga Type NR V-8 water-cooled , 260hp engine
Transmission: 4 forward, possibly 4 reverse
Power to Weight Ratio: 16.05hp/ton
Suspension: Leaf springs
Top Speed: 43.5km/h (27 mph)
Main Armament: 4.7cm Škoda A11 (80 rounds)
Vertical Guidance: N/A
Secondary Armament: 2x 7.92mm Vz. 37 (3000 rounds) (one hull mounted one Coaxial)
Armour: 32mm front 20mm sides 12mm bottom and top
Production: 2 prototypes