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9TP - Polish Premium Tier II tank proposition

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HussarKaz #1 Posted 07 August 2018 - 03:53 PM


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9TP - an unofficial name for the improved 7TP tank, ordered by the Polish Ministry of National Defense in 29th June 1939 and planned to be produced since autumn 1939. https://en.wikipedia.org/wiki/9TP

Polish Army ordered 100 tanks of the new design to be delivered before June 1940. In July 1939 the PZInż factory produced two additional prototypes to be extensively tested at tank proving grounds. While tests were generally favourable, it was noted that the new design had much lower speed than had been anticipated. It is unclear how many 9TP tanks were actually produced before the outbreak of World War II on 1 September 1939. It is assumed that the 11 tanks delivered to the Polish Army already after the start of hostilities were of 9TP rather than 7TP design. If this was the case, than the total number of 9TP tanks produced was 13 (two prototypes and 11 production models), with one 7TP with a new engine being an interim design. No documentation has survived however and this is by no means certain. The 11 tanks could have been either standard 7TP or 7TP with some of the modifications included, but not all of them. The tanks of this batch were incorporated in the 2nd Light Tank Company and took part in the fights during the Siege of Warsaw and served with distinction until the capitulation of the city on 27 September 1939.


It is also known as 7TP wzmocniony (7-tonne Polish, reinforced), 7TP wz. 1939 (7-tonne, Polish, mod. 1939), after the names of two prototypes. Some sources claim that 7TP wz. 1939 version entered mass production in September 1939.
Protracted designing-construction works of Polish tank prototypes and the lack of ability to furnish army with modern equipment from abroad gave the foundation for a huge 7TP development in 1938. This programme was mainly aimed at increasing tank’s military value throughout strengthening its armour and (due to envisaged weight increase) using much more reliable powertrain which was supposed to maintain good manoeuvrability and traction performance. In the mid-1930’s, a large experience had been collected, and significant achievements in the field of producing armour plates were reported. Employees of Laboratorium Mechaniczno-Chemiczne BBT Br. Panc. (Mechanical-Chemical Laboratory of Armoured Weapons Technical Research Bureau) in cooperation with Komisja Badania Blach i Płyt Pancernych Instytutu Metalurgii i Metaloznawstwa (Commission for Research of Armour Plates and Sheet Metals from the Institute of Metallurgy and Metal Science) and metallurgical industry representatives had carried a lot of arduous studies followed by endurance tests of homogeneous and cemented (case-hardened) armour. Owing to the fact that Polish industry had short tradition in manufacturing modern plates, such issue was considered as a top priority. These researches led to work out and master mass production of 3-50 mm thick homogeneous armour plates, and also 8-20 mm thick cemented ones.
What was crucial for tanks’ mass production was that metallurgical achievements had made it possible to devise new methods of welding such huge components as hull. In 1937, on the basis of tests results, Maj. Eng. Tadeusz Biemacki, the manager of metallurgy department in Labolatorium BBT Br. Panc., designed and accomplished 7TP’s experimental hull, made of 5-17 mm thick welded armour plates. It weighted around 1700 kilograms — significantly less than hulls built with the previous method, i.e. through superposing plates on a grit formed frame, and, later on, merging them by rivets or screws.
Furthermore, some steps forward in the field of combustion engines had been made. In 1936, the engineers from BS PzInż (Studies Bureau of the State Engineering Works) — Jan Werner, Jerzy Dowkontt, Wacław Cywiński — created prototype power plants of own design, including the PzInż. 705 carburetor engine (indicated for a new family of lorries), and its derivative modification: the PzInż. 725 (more powerful, designed for heavy goods tracked vehicles). Data sheet of PzInż. 725: 345 kg, 6-cylinder inline vertical, cylinder bore x stroke: 100 x 110 mm, capacity: 5180 cm³, 95 HP at 2800 rpm, compression ratio: 6.35.
By 1939, several prototypes of this engine had been built; although they were factory-tested, it was impossible to gain some experience from long term exploitation. Accordingly, at the beginning of 1938, the State Engineering Works received the brand new Saurer CT1D diesel engine, and its bulk production was about to be launched under the designation PzInż. 155. Data sheet of PzInż. 155: 600 kg, 6-cylinder inline vertical, cylinder bore x stroke: 100 x 110 mm, capacity: 7980 cm³, 100 HP at 1800 rpm, compression ratio: 16. The Saurer Company provided complete documentation and several model engines.  The production start-up was foreseen for 1939.
In April 1938, the Armoured Weapons Command ordered in the State Engineering Works a prototype 7TP tank with such power plant. One month later, it was finally built and delivered to Armoured Weapons Technical Research Bureau (the sample was probably made of iron plate).  The tested vehicle (loaded with extra weight in order to simulate heavier armour) was considered as better than the one with PzInż. 725 engine. Its only disadvantage was that the newer motor showed less abilities to overcome rough terrain capabilities, which were caused by weight increase, while keeping the same chassis.
The proposals for further 7TP modernization were presented in two projects:                                                            
– the first, proposed by Armoured Weapons Technical Research Bureau (7TP reinforced): this modification provided newly developed Polish PzInż. 725 petrol engine (95 HP), which was smaller than the diesel one, and welded hull, of a lower profile, with a slanted front plate of the combat compartment. The brand new power plant was mounted on a right side of engine compartment (a drive shaft was also moved to right side, so it would be less an obstacle for the turret's crew). What is more, the cooling system had been significantly changed: its cooling grates were removed from an engine deck, and replaced with slots in sides. The motor's mass had an influence on reducing overall tank weight. All these qualities weighted in favour of PzInż. 725. On the other hand, the use of petrol increased the risk of fire, and tank would be ignited by direct hit. The armour, while maintaining the 7TP's weight and traction performance, was to be up to 30 mm in front and rear (vertical plates), 25 mm on a front slanted plate and the driver's hatch, and 20 mm on sides and turret. The driver was to be equipped with two G wz. 34 reversible periscopes. 
– the second, proposed by Studies Bureau of the State Engineering Works, worked by Edward Habich (7TP mod. 1939): in this variant, the PzInż. 155 engine was used. The tank hull shape was slightly different, in comparison with the 7TP; only armour thickness increased from 17 mm to 40 mm in hull front, from 17, 13 and 9 mm to 25, 20 and 13 mm respectively in sides, and from 15 to 20 mm in turret's sides and to 40 mm in turret's front. Weight also increased to 10 594 kg, so strengthened suspension (320 mm wider tracks, road wheels with replaceable rubber), and C7P tractor's transmission were proposed.
Both project were submitted for consideration in May 1939. Despite the fact that the State Engineering Works draw heavy criticism from Col. Patryk O'Brien de Lacy (the head of AWTRS), its solutions gained Armoured Weapons Command's approval. Two prototype light tanks named 7TP mod. 1939 were ordered. In July, these vehicles (with some different adjustments — the one had standard transmission, the other adopted from C7P tractor) were finally built and received by Military Technical Inspection. Since 28 July, in the Kampinos Forest, tanks had been investigated and subjected to comparative trials with the third vehicle (it was to be experimental 7TP with CT1D engine, or another prototype tank called PzInż. 725).
During the first drives, the prototype with C7P's transmission obtained the best results and performance, so it was supposed to be launched in mass production. Unfortunately, the outbreak of the Second World War foiled these plans.
At the beginning of September, two or three experimental 7TPs mod. 1939, along with several different prototypes, were assembled in the WD BBT Br. Panc. (the Experimental Workshop of AWTRS), and in the SEW in Ursus (former Czechowice) near Warsaw. There is no information whether they were evacuated or stranded (damaged or concealed).
The genesis of 7TP reinforced/ 7TP mod. 1939:                                                                                                                  
– 1932:                                                                                                                                                                                  
The beginning of designing a homegrown light tank based on Vickers tank; it had been marked as VAU-33 (Vickers-Armstrong-Ursus).
– 1933:
Agreement between AWTRS and the SEW for ordering in the SEW two made of steel prototype tanks, according to the VAU-33 project.
– 1934:
August — completion of an early transitional model in line with VAU-33 project; it was implied as PzInż. 120 (7TP twin-turret), carried no. 1595, and a nickname Smok (Dragon). Intensive trials and comparisons between PzInż. 120 and Vickers tank.
- 1935
August – second iron prototype, reg. No. 1596, according to VAU-33 Słoń (Elephant) design is completed.  The tank was handed to CW in Modlin and then to 3 Bat.Panc. in Warsaw for training purposes. During the year many improvements were introduced to the Smok, which, as prototype, was still at a disposal to BBT Br. Panc.
- 1937
January – Bofors turret was mounted at the iron Smok. The procedure was conducted in Warsztaty Doświadczalne BBTech. Br. Panc. The vehicle was given designation PZInż 220 as a single-turreted version of the 7TP tank. Basing on earlier experiments,  mjr inż. Tadeusz Biernacki, director of the metallurgy division of the Laboratorium BBT Br. Panc., designed and manufactured prototype hull for the 7TP tank. It was made from steel plates with thickness from 5 to 17 mm welded together and weighted 1700 kg. 
- 1938
The DBrPanc. ordered prototype 7TP tank with experimental Saurer CT1D/PZInż 155 engine from the PZInż.
Circa 25.05.1938 the 7TP prototype (reg. no. 1766) with the CT1D was handed to  BBT Br. Panc by PZInż for testing purposes. The tank had additional ballast attached in order to simulate the weight of the thicker armour. The tests were conducted in autumn of 1938 in Kompania Ćwiczebna Centrum Wyszkolenia Br. Panc. The tank number 1766 traversed 548 km during tests, the engine worked for 29 hours and 55 minutes. The CT1D was considered better than VBLDb, but the offroad capabilities were worse as the current chassis was kept.
- 1939
18.02.1939 or 21.03.1939 – the protocol from the tests of the prototype 7TP PZInż with the engine CT1D was written and the tank was rated well. The tank without mock-up ballast imitating the strengthened armour was 210 kg lighter than standard 7TP. The decision regarding further development — altering the design of the vehicle and adding additional armour — was made. Two parallel projects were started: BBTech Br. Panc and PZInz.
Presentation and evaluation of two projects (not final vehicles!) of the 7TP reinforced/9TP was conducted. Despite the criticism of design choices proposed by the PZInż by the BBTech Br. Panc., the commission of Dowództwo Br. Panc.approved the vehicle proposed by the PZInż.
As result, two prototype vehicles were ordered from the PZInż, called 7TP wzór 1939. The changes were to be introduced on two 7TP tanks being in on-going production, perhaps immediately with full-featured armour plates (as proposed by the BBTec Br. Panc). The BBTech Br. Panc made a single vehicle according to their own project using  iron plates based on the parts belonging to the first model 7TP tank (most probably the iron Smok still in possession of the WD BBTech Br. Panc.).
28/31.07.1939 and 03.08.1939 - the tanks were given for acceptance and tests to the military.
Vehicle no. 1 adhered to the proposal by the PZInż but was equipped with standard gearbox from 7TP. The PZInż vehicle no. 2 fully adhered to the PZInż proposal from May/April 1938, as it employed gearbox from C7P. The third vehicle was presumably the experimental 7TP with the CT1D/PZInż 725 engine. The best results were achieved by the PZInż no. 2 vehicle (with C7P gearbox) and this tank was to be made into series production.. 
The evaluation of vehicles from the PZInż and single one from the BBTech Br. Panc were conducted in the  Puszcza Kampinoska (Kampinoska Forest).
The paper regarding tests and improvements made in the PZInż no. 2 vehicle (C7P gearbox) was made.
- moving the periscope/sight 80 mm forward,
- window of gunner’s left-side turret periscope raised 80 mm,
- direction scale added to the commander’s observation periscope,
- more efficient turret rotation drive was introduced (as the turret was heavier),
- studies regarding the improvements of ammunition were outlined,
- the lack of possibility of adding driver’s machine gun due to the mantlet was stated,
After capturing Warsaw, both prototypes were probably taken by Germans or hidden/destroyed by the Ursus employees.
According to the photographies, at least part of the PZInż prototypes stayed in Ursus (vide known photos of the PZInż 130). It would explain why the Germans could capture two vehicles. 
Was the third prototype (BBTech) evacuated?
7TP reinforced, BBT Br Panc factory prototype, shown at 20.04.1939 (rejected prototype)
Characteristic features:
- welded armor with thickness in range 8-30 mm, evenly laid, mass similar to the series 7TP, about 9858 kg with the service, sides of the vehicle made from two plates,
- original 7TP suspension,
- the difference of axial loading limited to 68 kg from 785 kg in standard 7TP,
- ultimately carburetor engine (powered by petrol) PZINż 725 with power of  95-100 HP (maximal about 105 HP), weight 370 kg, requires single radiator. Standard Saurer VBLDb weighted 850 kg and required two radiators. The engine was located near the side of the hull, behind the driver. The engine was not series produced yet,
- the Cardan shaft (without joints) was altered and moved to the side of the vehicle, eliminating the obstacle that hindered the ability of crew to work inside of the tanks,
- standard gearbox (aluminum casing),
- 130 mm (to 1988 mm) lower profile of the tank due to smaller engine, 
- favorable silhouette (skewed frontal plate, different rear etc.),
- more space inside, increased crew comfort,
- two wz. 34 periscopes for driver and commander,
- thicker rubber layer on the road wheels,
- intended speed of 32-34 km/h (on road?),
- removal of all air circulation shutters, introducing solution as in  „Skoda”/”Koblen Danek” tanks.
7TP wz.39, prototype made by PZInż (E. Habich) shown at 05.04.1939.
Welded lower armor plate with thickness of 5 to 40 mm., uneven thickness: 40 mm in front, 25, 20 and 13 mm on sides, 40 mm turret front, 20mm turret back and sides, rear and upper armor without changes in relation to initial design of 7TP tank, 
- PZInż 155/CT1D engine — license model produced by PZInż since early 1938.
- Gearbox adopted from C7P tractor (aluminium casing),
- Increase in weight to ca. 11 tons (different sources claim increase of 729 or 800 kgs compared to standard version).
- Reworked suspension, track width 320 mm (standard version — 267 mm)
- Slightly changed outline (three additional plates of side armor?)
- Road wheels covered with rubber,
- substantially increased pressure of front wheels.
- Increased mass may result in engine overheating issues (radiators in standard version were working at maximal power).
- Speed up to 26,6 km/h on the road and 11,5 km/h off-road (tested in Kampinos village).
Some sources state that 11 9TP tanks did take part in fights - defending Warsaw.
With is probably not true... 
As stated above, pictures show at least part of PZInż prototypes to have remained in Ursus
Fate of these machines remains uncertain. The prototypes were either captured by Germans after taking Warsaw or destroyed by Ursus’ workers.
Third prototype 7TP (reference) could have been evacuated and was cannibalised. 
There are no sources that could unequivocally confirm accounts of 11 9TP tanks having been produced and used during defense of Warsaw.
People claiming that 7TP reinforced or 7TP wz.39 were used in combat are often referring to the following publications:
- A. Jońca, J. Szubański, R. Tarczyński: Wrzesień 1939. Pojazdy Wojska Polskiego. Barwa i broń., Warszawa: Wydawnictwa Komunikacji i Łączności, 1990, str. 32, 52-58,
- A. Wszendyrówny, M. Wodejko: Czołg 7TP w dokumentach Centralnego Archiwum Wojskowego, w: "Do Broni", nr 1/2009, s. 96.
The following statements might be found there: 
2nd Light Tank Company of Warsaw Defence Command (...) Equipment: 11 7TP tanks (from PZInż current production) (p.32)
In September, about a dozen (11?) 7TPs rolled out of factory’s current production. (p.52)
The prototype (...) was constructed in 1938 and at the beginning of 1939 tests were ended. As the consequence, contracts for delivery of new armor plates were signed. Therefore, it is reasonable to suspect, that the tanks delivered for the army in 1939 had new armour scheme.
As we can see, instead of explicit confirmation, only suspicions are found, and 11 tanks mentioned in excerpts above were probably part of last 7TP production series based on C7P tractors.
Blueprint comparison:
Blue — 7TP reinforced, according to BBT Br Panc shown at 20.04.1939.
Red — 7TP wz.39, according to Biuro Studiów PZInż (E.Habich) shown at 05.04.1939.

Turret of 7TP reinforced and  7TP wz.39.
Unfortunately no picture of 7TP reinforced or 7TP wz.39 turret was ever made.  We know only that the armor would be thickened compared to the 7TP - 40 mm in front, 20 mm sides and back.
Based on sources published at:
Andrzej Wszendyrówny, Marcin Wodejko, Do Broni 1/2009, Styczeń-Luty 2008 - Czołg 7TP w dokumentach Centralnego Archiwum Wojskowego
Kwartalnik historyczno-modelarski, Militaria Vol.1 No.5 Zeszyt Specjalny - Czołg lekki 7TP część pierwsza

Edited by HussarKaz, 07 August 2018 - 04:20 PM.

Balc0ra #2 Posted 07 August 2018 - 05:08 PM

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40mm of armor? That's way to much effective upper plate armor for a tier II that faces tier 1 guns at that angle. Even if the lower plate is half as thick as the 7TP atm. And it's turret armor is half vs the armor layout you had above of the 9TP. It would be a tad strong for tier II. Could work for tier III tho, as the T-127 with it's 40mm upper plate at a high angle that gives it 62mm effective give or take. 


Tho there is a tier II Polish Premium light currently in testing. Most suspect it's this years gift tank for Xmas. It's the TKS 20mm. Or the TK-3 if you will. A turretless light with a 20mm clip gun with 43 pen and 55 gold pen on tier II. 11 damage pr shot. Has a 10 round mag, 0.188s between each shot, and a 6.7 sec reload time. Maybe not as interesting. But TKS was a tank many did ask for as well early on. 

Edited by Balc0ra, 07 August 2018 - 05:09 PM.

HussarKaz #3 Posted 07 August 2018 - 05:27 PM


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9TP turret would be huge weakspot even with 40 mm in front due to its flat front design. M14/41 has much more powerful turret frontal armor and is not OP. R35 has round turret and 40 mm armor all around - and still is possible to beat ;) comparing to T-127 is no use due to the fact that T-127 is vastly quicker and have slopped armor in both hull and turret. Furthermore, 9TP turret cheeks are weaker than T-127s.

Moreover, Tier I tanks see many Tier II tanks rarely and they are usually forced to attack Tier II tanks from the side, where 9TP has 20-25 mm.

Still, if the tests show that 9TP is too powerful, it could be eventually put in Tier III, but I am afraid that Bofors 37 mm would be too weak cannon for Tier III with its 55/78/19 pen and 40/40/50 damage (data taken from Strv m/38 using that cannon on Tier II).

You have mentioned the TKS, but I am believed that there is a room for more than one Polish Tier II premium tank - especially due to the fact that Poland was eliminated in the first two months of war. So any interesting Polish tank prototype may appear in game as premium tank in Tier I or II only.

Edited by HussarKaz, 07 August 2018 - 05:34 PM.

Alora_V #4 Posted 07 August 2018 - 07:45 PM


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OP has used the wrog visualisation that somebody put in War Thunder forum and now it lives with its own life. It is incorrect.

The correct is below. The slopped armor version (PPTBr) was 30 mm. Habich (PZInż) version had a front in the same shape as 7TP. It has a flat 40 mm weakspot on front.


Moreover, notice that the turret roof is not perfectly flat. The frontal part of the roof will be a huge weakspot with 8 mm (7TP wzmocniony) or 10 mm (7TP wz 39 by Habich).



HussarKaz #5 Posted 08 August 2018 - 09:42 AM


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It looks you are right, thank you.


Now the PZInż version of 9TP looks pretty balanced - the front is safe from machinegun fire but it has several frontal weak spots. Pretty similar situation to M2 Light, but the 9TP would be much slower.

7TP Reinforced would be even UP due to the fact it has very weak turret.


It looks like there is a room for even two premium vehicles - more money for WG and more fun for us :D

7TP wz. 39 would be available in the Premium Shop all the time, alongside with T2,

7 TP Reinforced would be sold in packages


Let's move to the gun.

Polish licensed version of Bofors 37 mm should share its statistics with the Swedish original gun.


37 mm armata czołgowa wz. 37 Bofors

DPM 1,065.05
Damage 40/40/50
Penetration (mm) 55/78/19
Reload time (sec) 2.25
Rate of fire (rnds/min) 26.63
Aim time (sec)1 .73
Dispersion 0.40
… moving 0.29
… tank traverse0.29
… turret traverse0.06
… after firing2.88
… damaged1.92
· · ·
Damage vs. modules50
Caliber (mm)37
Shell velocity (m/s)785
Max range (m)720
Ammo capacity100
Potential damage4,000
Depression -10 degrees

Edited by HussarKaz, 08 August 2018 - 09:48 AM.

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