Author: Tadeusz Pakula
Illustrations by Jaroslaw Janas
Thanks to TE for giving us permission to post this article.
WB-10, Polish Medium tank prototype from 1927
The WB-10 (sometimes written W.B.10) was the first tank designed and built in Poland. It was also one of the only Polish interwar armored vehicles that was completely original. Without drawing inspiration from foreign vehicles, as was the case with the TK tankettes or 7TP. The WB-10 was planned as a successor to the French-bought Renaults FT. Unfortunately, the WB-10 was a complete failure and the whole project landed in the dustbin of history.
Very little information has remained to this day. Two photos exist which are speculated to be of the WB-10 prototypes, somewhere near Warsaw in 1939. A supposed drawing of the vehicle is also widely circulated on the internet, but it is not compatible with the vehicles seen in the two pictures.
It is highly important to stress that most of the information with regards to this vehicle should be treated with a healthy dose of skepticism until primary sources can be discovered and shed more light on the curious WB-10.
A new Polish tank
In 1925, the only tanks available to the Polish army were the Renault FTs received in 1919. They were still usable but needed modernizations. The WWI era FT had a lousy maximal speed, a weak armament and had problems with terrain obstacles.
The Polish Army started negotiations with Great Britain over the purchase of British Medium Mark D tanks, but this endeavor failed. Finally, the Army decided that the Polish arms industry should become independent and build its own tanks. So, in 1926, the Polish press announced a contest for a project of a new tank.
The requirements for the new 12-ton design were quite strict
• All-around armor strong enough to resist the 13 mm bullets from 50 meters
• Front and sides strong enough to resist 47 mm shells from 500 meters
• One 47 mm (or higher caliber) cannon
• One 13 mm anti-aircraft machine gun
• One 7.92 mm machine gun for anti-infantry use
• Periscopes giving 360° of vision around the tank
• Engine with a warming and cooling system
• Smoke screen device
• Radio with 10 km range
• Maximal speed ≥ 25 km/h
• Operational range ≥ 200-250 km
• Possibility to ride on 35°- 40° slopes
• Possibility to cross 2.2 meters ditches, 0.8 meters walls and to ford 1 meter of water
• Average ground pressure ≤ 0,50 kg/cm2
The contest entries were underwhelming. As the tank concept was still a novelty, tracked vehicle designers and engineers were rare in Poland. Only three projects were reported – and only one project, the WB-10, designed in cooperation by two companies: S.A.B.E.M.S. and WSABP “Parowóz” (“Steam Locomotive”) received the green light.
Moreover, the two companies designed two alternative versions of the vehicle and built two models powered by small electric engines. They were designed by professor Ludwik Tadeusz Eberman of the Lviv Polytechnic, who was working for WSABP.
Until this contest, the “Parowóz” company built steam locomotives and S.A.B.E.M.S. was building engines.
Unfortunately, little to no information about the two other competitor projects are available. They were supposedly armored cars or wheel tanks, not true tanks. One of them supposedly had four axles and the second one just two.
Rise and disappointment
The new project was rather modern and complicated for the time. It was a wheel-cum-track tank, so it had the possibility to change its way of running depending on the terrain, with the wheels being preferred on roads and the tracks on rougher terrain.
Some sources claim that the WB-10 was also amphibious and could lower or raise its hull. The latter claim probably refers to how the wheel-cum-track system worked, and not that the vehicle had a sort of hydropneumatic suspension. Moreover, the chassis could be used as basis for a special tractor.
The army ordered a prototype of the new tank. The construction took a significant amount of time, but two tanks were eventually ready for testing. Regrettably, the WB-10 came to be a giant disappointment. The vehicle suffered a lot of breakdowns due to its complicated design and mistakes in the project. These caused problems with driving the vehicle and according to other versions the WB-10 was not even able to start the trials. These failures brought about the quick cancellation of the WB-10 project. The new Polish tank was rejected.
After this failure, the negotiations with Great Britain were restarted, resulting in the acquisition of the Vickers 6-ton and the eventual creation of the 7TP.
The fate of the WB-10 prototypes is unknown. They were probably just scrapped after the trials or sent to some army station as technical oddities. However, it is almost guaranteed that they were finally destroyed.
As the WB-10 was a total failure, it faded from memory quite rapidly. After the destruction brought about by World War II, a lot of the information about the vehicle was lost.
The WB-10 was a wheel-cum-track tank. It had four wheels which could be lowered, raising the tracks of the ground. If the tank was to go cross country, the wheels would be raised and the vehicle would use its tracks.
Nothing is known about the engine. However, the designer Prof. Eberman also worked on diesel-type engines, so it is possible the vehicle had such an engine. The WB-10 was probably a massive and slow tank, typical of the period. If it indeed had any amphibious qualities, it is unknown if it had any propellers or if it used its tracks to paddle the water.
The contest requirements suggest that it was able to fit a 47 mm or higher caliber cannon. However, nothing else is known of it.
The 13 mm machine gun is also unknown. The French 13.2 mm Hotchkiss M1929 machine gun was designed years after the WB-10. The 13 mm caliber was most probably just an approximation for 12.7 mm, the typical caliber for anti-aircraft machine guns. The 7.9 mm machine gun was probably the 7.92 mm Hotchkiss wz.25. This was a widespread Polish machine gun that was an improved version of the French Mle 1914 machine gun.
The prototypes could have been painted in khaki camouflage – this color was typical for Polish prototypes (like the Renault TSF or 4TP).
Photos and pictures
Two photos of two unknown vehicles have appeared on the Odkrywca.pl Polish website. It is claimed they were taken near Warsaw in 1939. The photos apparently come from the Patton Museum collection.
They present two groups of soldiers next to some FIAT 621 trucks and two big, mysterious tanks. These vehicles do not resemble any known tank in Polish service or anywhere else in the world. Their old-style design suggests that they may be the WB-10 prototypes, left in some army station.
The vehicle in the foreground is visible in both pictures and, although the soldiers obscure it to some degree, its design can be observed. The background tank is barely visible in one of the pictures. It seems as though it differs from the first tank.
The first tank is lacking its wheels, which were most likely removed or reused on some other vehicle. However, in one of the photos, a large bar is seen protruding from the side of the vehicle. This was most probably one of the attachment bars for the wheels. Both the vehicles are large and tall and almost certainly too heavy to be amphibious. The first vehicle has a large decagonal turret, with no hatches or other elements visible.
A third photo has emerged on the Odkrywca.pl forum. It seems to show one of the same tanks, but at a later date. The general shape and details indicate that this is indeed one of the unknown tanks supposed to be the WB-10. The vehicle appears to have been partially dismantled, missing its turret and quite a few of its armor plates. However, the two supposed wheel supports are clear in this shot. Also, this is the only photograph of the front of this vehicle.
The Czech HPM magazine, in its nr 9/2001 edition, published some schematics of a tank claimed to be the WB-10. Where the Czech artist got his inspiration is unknown. The schematics don’t seem to resemble the two tanks in the photos.
One of the other designs?
The Polish writer Janusz Magnuski mentions in his book “Wozy bojowe” (Wydawnictwo Ministerstwa Obrony Narodowej, Warsaw, 1964) that there was also third tank prototype built for the contest. It is possible it was one of the other two wheel tanks that competed against the WB-10. This third tank was designed by professor Czerwiński (no other information known about this person) and failed just like the WB-10.
Some Czech sources claim that only one WB-10 tank was built and the second prototype was another vehicle, called the WB-3. The WB-3 was apparently tested in 1927 and the WB-10 prototype was built as an alternative. According to this theory, the WB-10 tank was never completed. Also, only the WB-3 was a wheel-cum-track vehicle, while the WB-10 only had tracks. However, no Polish source mentions the WB-3 tank.
“Wozy bojowe” by Janusz Magnuski (Wydawnictwo Ministerstwa Obrony Narodowej, Warsaw, 1964)
“Czołgi Wojska Polskiego 1919-1939” by Janusz Ledwoch (Wydawnictwo Militaria, Warsaw, 2015)
On the Odkrywca forum