The FReeper Foxhole's TreadHead Tuesday - The 7TP/7-Tonowy Polski Light Tank - June 1st, 2004

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[SAMWolf]

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7TP / 7-Tonowy Polski Light Tank

In 1928, British Vickers-Armstrong designed the 6ton Tank Mark E and of which in 1931, Poland purchased 50 examples. 6ton Mark E was not accepted by the British Army but Vickers sold it along with a licence (in some cases) to Bolivia, Bulgaria, China, Estonia, Finland, Greece, Japan, Portugal, Romania, Russia (T-26 series) and Thailand (Siam). Two types Mark A and Mark B were purchased along with the licence. 16 Model A and 22 B were delived in 1932 and 1933, while the rest remained as payment for the licence or were delivered as spare parts. The twin turret Mark A was armed with two 7.92mm Hotchkiss wz.25 and in late 1930s rearmed with 7.92mm Browning wz.30 machine guns. Single turret Mark B was armed with 47mm Vickers-Armstrong gun and 7.92mm wz.30 machine gun. The main problem with 6ton Vickers was its Siddeley engine, which easily overheated. After examination in Poland, it was decided to modify Mark E and start the development of their own light tank by improving Mark E. New tank development program was designated as VAU-33 (Vickers-Armstrong-Ursus 33), either jw (single turret) or dw (twin turret).


7TPdw-1938.jpg

Polish designers attempted to modify original Vickers tanks as late as 1936, including various armament configurations in twin turret models. Polish designers also worked on replacing original Armstrong-Siddeley engine with licensed built Swiss Sauer diesel engine as well as on improving its armor protection. Experience gained during the work was used in the development of new Polish tank and Vickers tanks remained in service to the outbreak of war without major modifications (e.g. cooling system was improved). In 1934, the development of domestic light tank designated 7TP (PZInz.220) based on Vickers Mark E started.



In Spring of 1935, it was accepted for production and production of first 7TPdw with two small turrets, each armed with 7.92mm Browning wz.30 machine gun started. Other alternate armament was 13.2mm Browning wz.30 heavy machine gun mounted in one turret and 7.92mm Browning wz.30 machine gun in the other. Also considered was configuration with 37mm Puteaux SA 1918 gun in one of the turrets. 7TPdw was considered to be the temporary solution and only some 24 were produced, while the rest was finished as 7TPjw tanks. Early 7TPdw were mounted with turrets removed from 22 Vickers tanks in 1934, which were converted to single turret model.


7TP Light Tank, 1939

Next variant was to be armed with a single turret armed with a heavier gun. Various designs and prototypes were presented and armaments included: 20mm, 40mm, 47mm and 55mm guns. In late 1936, second variant 7TPjw was ready and entered production in late 1937. It mounted a single turret manufactured by Swedish Bofors, armed with 37mm Bofors anti-tank gun and one 7.92mm Browning machine gun. Vehicles produced from late 1938, were fitted with turret mounted storage bins to mount 2N/C radio equipment. Original 7TPdw were slowly being converted to jw variant and by September of 1939, only 16-24 were in service. All 16-24 were at the training centre near Warsaw and in September of 1939, took part in the defence of the city. In 1938/39, work on new 7TP started and two designs were made for new tank designated as 9TP Both variants were to have modified 7TPjw's turret, a new engine (Saurer CT1D / PZInz.155 diesel engine), strengthened suspension and wider tracks along with improved armor protection. First variant was to be uparmormed (up to 40mm) version of 7TP, while second had more angled front armor. Outbreak of war stopped any futher development of 7TP and 9TP.



In January 1937, Sweden became interested in purchasing or renting of single 7TPjw for testing purposes along with a purchase of 20 to 60 unarmed tanks and C7P tractors, but Polish side was not interested. In April of 1937, Bulgaria and Estonia were interested in purchasing 7TPjw tanks. Estonia wanted to buy 4 tanks, but Poland was willing to sell only 7TPdw tanks and it was planned to create a hybrid of 7TPjw hull mounted with Vickers turret armed with cannon. In November of 1937, Holand was interested in 7TP, but also no transaction took place. In 1938, technical documentation for 7TPjw was send to Turkey in preparation for the transaction, which never took place. At the same time, Poland considered exporting 36 7TPjw tanks and Yugoslavia and Greece were both interested, but the transaction never took place.


Polish - VickersE-Twin

Overall from 1935 to 1939, 7TP was built by Panstwowe Zaklady Inzynierii (National Engineering Works) at Ursus near Warsaw, in only two main variants - jw (single turret) and dw (twin turret). Polish designers also developed light (artillery) tractor / troop carrier based on 7TP's chassis designated C7P. Production started in 1935 and first units received tractors in the same year. In 1937, plans were also made to produce self-propelled anti-aircraft tank based on 7TP armed with two 20mm FK-A wz.38 L/73.5 automatic cannons (used to rearm TKS tankettes). The entire project was cancelled in 1938 and all efforts were concentrated on production and modernization of Polish armored fighting vehicles. Also few special rail transport cars were made especially for 7TP tanks (similar to those made for Polish Renault FT-17 light tanks) to allow them to travel as part of armored trains.


First prototype of 7TP - VAU-33-2

In September of 1939, Polish Army had only 136 7TPs (24 dw, 97 jw and 11 jw produced in September of 1939 along with 4 prototypes made of regular plate), which equipped two Polish light tank battalions (each with 49 tanks) and other units. During Polish Campaign, 7TP proved to be a match for any German Panzer. Some captured 7TPs were painted in Panzergrau with German markings and were presented during the victory parade in Warsaw on October 8, 1939. Later on captured 7TPs were used for internal policing duties and later on as artillery tractors. Number of captured 7TP tanks, especially jw variants was tested by the Soviets at Kubinka in 1939/40. Today, parts of 7TPjw light tank can seen in the Museum of Polish Armored Forces in Warsaw, Poland.

[SAMWolf]

The 7TP, VAU33dw, VAU33jw, 7TPdw, 7TPjw

All the names above have been seen in western writings as a designator for the Polish production of the Vickers 6-ton tank. All are correct, and misleading. Every designator is correct if used within the right context. Only the prototypes used the designator "VAU33-dw or VAU33-Jw". The VAU33-dw was the dual turret model while the VAU33-jw was the single turret type. 7TP tanks were produced with two designations; the 7TPjw and the 7TPdw. The 7TPdw was the dual turret design. Most writings simply state "the 7TP" and that designation is used most often to refer to the single turret (7TPjw) model. The single turret model was the tank that Poland was the most proud of and was their most modern production design. By the start of WW2, the 7TPdw was no longer in production and was considered slightly out of date. Some writings refer to the designators VAU33jw and VAU33dw. This designation is used in some Western sources for Polish Vickers Mk.E tanks. It's especially used by some model manufacturers, but this is an ERROR in fact. VAU is a short of "Vickers-Armstrong-Ursus", sometimes they supplement it with "wz.33". The Ursus factory had nothing to do with Vickers-Armstrong tanks. Polish researcher J. Magnuski wrote, that "VAU" was an initial designation for Polish Vickers development project, which led to 7TP tank. Some sources state that the VAU-33 was a prototype of 7TP and was a modification of the Vickers Mark E with a Swiss diesel engine Saurer VBLDb.

Unlike many nations, Poland did not simply produce (or even buy) more clone Vickers 6 ton tanks, but actually improved on the already excellent basic design. Poland's 7TP was the first step in an uncompleted process (interrupted by WW2) of gaining engineering and industrial ability needed to produce a truly Polish Tank.


A back-door view of a prototype 7TP turret interior (serial turrets had no back door). From the left, visible are: periscopic sight, pistol grip of 7.92mm wz.30 TMG, telescopic sight, 37mm wz.37 gun's breech guard and a pipe for case ejecting, and commander's periscope. An interior of serial turrets was similar.

The Vickers tank was well within the capacity of the Polish industrial technology, and the design offered some potential for further development. The PZI design bureau was tasked with the study of making a homemade copy. PZI produced the 7-TP, a 9-ton twin turreted tank that was to be a considerable step forward in design over the Vickers original. At first the original engine of the Vickers was installed, but this was replaced by a license-built Saurer 6-cylinder diesel engine which developed 110hp. This made the Polish 7-TP the world's first diesel-powered tank to reach production status. The 7-TP's armor was also 4mm thicker than the Vickers originals. The first 7-TP to be built by PZI left the works in 1934. While the production of the modified twin turret model 7-TP was proceeding, it was decided to introduce a single version carrying a Bofors gun. This variant appeared in 1937, but the production was slowed by the difficulties of making armor plates and procuring the turrets from Sweden.


Dismounted co-axial mounting of wz.37 gun and wz.30 TMG of 7TP tank.

In 1939, after some minor arguments unsuitable armor thickness, PZI got involved to evolve a heavier variant with an improved engine, welded armor thickened up to 40mm in front, a strengthened suspension, wider tracks and a turret with a rear overhang which could accommodate both transmitter and receiver radio sets. The new up-armored 7-TP, which now weighed 11-tons, did not have time to go beyond the pre-production stage before the events of 1939. During the nineteen thirties and during the development of the 7-TP, the question of designing tanks in Poland had become a very controversial matter. Two schools of thought were in contention: the first one defended the launching of domestic design and production programs, the second one (represented by the Chief of the Armored Force himself), considered this as a waste of time and money which could be better spent in purchasing well-proven foreign tanks. Nothing came of these debates except friction and the slowing of progress. A total of 169 7TPs saw service.

[SAMWolf]

Based on a Vickers Armstrong 6 ton design, a popular product world wide, the 7TP was produced in Poland starting from 1931. Poland purchased 38 Vickers E tanks (22 twin turret and 16 single turret) for the Polish Army along with the license allowing Poland to produce them in Poland. The 7TP was considered a light tank by standards at the time. Some early models had 2 turrets, each mounted a machine gun. Later models had a single turret with a 37 mm cannon as shown above. The 7TP (with the 37 mm cannon) was more than a match for German Panzer 1 and 2, and an equal of Panzer 3's except in armor protection*. The German army was so impressed with this design they incorporated as many 7TP tanks as possible into their service.


Captured 7TP tanks in German service

*Late models had 40 mm of frontal armor. This made the tank stronger than the Panzer 3 of that period. In fact, the Germans lost a great deal of armor in the Polish campaign. That was one of the reasons for the "phony war" on the western front. Germany needed time to rebuild/repair their armor.


Warsaw September 1939 by David Pentland
Polish 7TP (Twin Turret) light tank of Captain F. Michalowski's training company breaks out from the street barricade to counter attack German reconnaissance elements.

Though Poland had limited industrial capacity, there was real interest in tank warfare and design. Sadly (and lucky for the Russians and Germany), the best designs had not reached production level prior to September 1939. The Polish army was equipped with less than 950 tanks in an odd mixture of imports, tankettes, and light tanks. This force had to face a German Panzerwaffe of over 3000. Soviet tank numbers are unknown.




The Poles were far ahead of many nations in tank development. Using the Sauer engine made the 7TP the worlds first diesel powered tank. The 7TP was the Polish version of the Vickers 6 ton (twin turrets) but with thicker armor (17 mm). This actually made the tank a 9.5 ton machine. In 1937 the unit was redesigned to a single turret with a 37 mm cannon. The final model of the 7TP had a larger turret and up to 40 mm of armor (welded). The model also included better suspension and wider tracks.

Specifications

Crew	3
Engine	Armstrong Siddley Puma 91.5 hp air cooled, or Swiss Sauer VBLDb 110 to 115 hp water cooled. Using the Sauer made the 7TP the worlds first diesel powered production tank.
Weight (battle)	11+ U.S. tons, 9.9 metric tons
Speed	22.98 mph
Range	150km (road) 130km (cross country)
Communications	7TPjw came equipped with N2C
Armament	7TPdw had 2 x Browning 7.92mm MGs. 7TPjw had 1 x 37mm Bofors and 1 x Browning 7.92mm MG.
Height	6.61'
Width	7.55'
Length	14.96'
Armor	5 - 18mm. Up to 40 mm (late models).
Power to Weight	11.1 bhp/ton
Track Ground Pressure	0.6kg/cm2

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Additional Sources:

mailer.fsu.edu/~akirk/tanks/pol
derela.republika.pl
www.wargamer.com/articles/captured_tanks
www.military-art.com
www.wojmar.republika.pl

[SAMWolf]

When the Wehrmacht blasted into Poland in 1939, their main opposition was the TK-3, the 7TP, and about 50 French-built R35’s. The TK-3 was a tankette (better known as deathtrap) armed with only machineguns, and proved easy meat for the Panzers.




The 7TP was another matter: this light tank was armed with a 37mm gun and was capable of defeating the Panzer I and II’s that made up the bulk of German armor at the time. The tank had a 110 hp engine producing a speed of 22mph with a range of 93 miles. Armor was 5mm-17mm, with a weight of around 10 tons. There was a crew of three, and armament other than the 37mm consisted of two 7.92mm machineguns.



The Poles had two battalions equipped with the 7TP, and after the capitulation, the Germans used as many as they could salvage. They were initially used as tanks for policing in occupied territories but were later converted to artillery tractors. Thus started the practice of applying the Black Cross to a vanquished foe.

[SAMWolf]

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UPDATED THROUGH APRIL 2004



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It's TreadHead Tuesday!


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[SAMWolf]

Good Night Snippy.

[alfa6]

Night shift bump for Treadhead Tuesday

Regards

alfa6 ;>}

[SAMWolf]

Open 24 hours. :-)

Thanks, alpha6

[Neil E. Wright]

hiya kids,

may I point everyone to this thread:

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Walk on Warrior! (Hand Salute!) Semper Fi!

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[alfa6]

Ah the joys of 12 hour shift work and only having one 'puter that I can get FR on.

Well it could be worse and I don't want to find out how :-)

Back to work as I my timer went off.

Regards

alfa6 ;>}

[snippy_about_it]

Thanks Neil.

[snippy_about_it]

Good Night Sam. Thanks for today. ;-)

[Aeronaut]

Good morning Tonk and all.

[Aeronaut]

Oops..., I meant: Good morning Snippy.

Durned cut lists.

[E.G.C.]

Good morning Snippy and everyone at the Freeper Foxhole.

[Tax-chick]

Good morning, all. Poles with tanks ... what'll they think of next?

[GailA]

Good morning

[The Mayor]

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Present!

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