PIBWL presents:

Armament of the Polish armoured vehicles 1918-39 - part II

PIBWL Polish Armour page [ Main page ] [ Polish armour / armoured trains ] [ Polish armoured units ] [ Steel Panthers ] [ Links ]
  © Michal Derela, 2003-2008 Updated: 19. 07. 2008 - improved text, added photos


Part I
 
Part II
 
Machine guns Tank cannons
- 7.92mm wz. 08 (Maxim)
- 8mm wz. 14 (Hotchkiss)
- 7.92mm wz. 25 (Hotchkiss)
- 7.92mm wz. 30

- other machine guns
- machine guns' data
- ammunition 7.92x57mm
- 20mm wz. 38 FK-A
- 37mm wz. 18 (SA-18) Puteaux
- 37mm wz. 36, wz. 37 Bofors
- 47mm Vickers QF
- 47mm wz. 25 Pocisk
Armoured trains' artillery

Note, that the values of armour penetration of one weapon might not be automatically comparable to the penetration values of other weapons, especially if the used source is different, and all the test conditions, like armour inclination and armour hardness, are not identical.



Tank cannons

The first trial of using 20mm gun in a Polish armoured vehicle was made in 1935, when 4 semi-automatic guns (anti-tank rifles) Solothurn S18-100 were bought in Switzerland. One of them was mounted and tested in the TKS tankette, what proved, that arming tankettes with 20mm automatic guns was advisable (more on tankettes with cannons page).

Solothurn gun mounted in a tankette TKS (it can be distinguished from FK-A gun by a shorter barrel and smaller mounting cover). [source 4]


20 mm wz. 38 model A (FK-A)

This weapon was classified in Poland before the war as the heaviest machine gun (najcięższy karabin maszynowy - nkm). It was designed in 1937 in Fabryka Karabinów (Rifle Factory) in Warsaw by Bolesław Jurek, as "model A" (the designations: FK-A or FK wz.38 are an abbreviation of the factory). An initiator of works upon Polish 20mm automatic cannon was the airforce, then it was decided, that a weapon must fulfil also demands of the armoured weapons and the infantry, as an anti-aircraft weapon.

Click to enlarge
The prototype of model A gun on anti-aircraft tripod mounting. [source 4]
Click to enlarge
A pattern tankette TK modified and rearmed with 20mm FK-A gun [source 4]

The prototype of model A gun was completed in November 1937. As a tank gun, it was evaluated as better, than tested foreign guns Oerlikon and Madsen. Tests proved, that it was accurate and reliable, its construction was simple and its armour penetration was better, than of tested foreign guns. It penetrated the same armour plates from a distance 200m further. In 1938, model A cannon was accepted in a limited number as a tank armament and anti-aircraft weapon, until the works upon improved guns (models C and D) would be completed. For anti-aircraft duties, heavy and light tripod mountings were worked.

In May 1939, it was decided to rearm 80 tankettes TKS and 70 tankettes TK with 20mm guns. Rearming of all tankettes was also considered. Rearming of TKS tankette demanded only minor changes in its armour, but rearming of TK tankette demanded a modification of a superstructure front, making its look similar to TKS. A light tank prototype 4TP (PZInz.140) and an amphibious tank prototype PZInz.130 also were to be armed with the 20mm gun, but they didn't enter production.

Initially, 200 guns were ordered, to be delivered by February 1940. A serial production started in Zieleniewski factory in Sanok, while barrels were produced in SMPzA factory in Pruszkow. In 1939, hasty efforts were carried out to ensure and coordinate the quickest deliveries of guns, sights, mountings and additional armour parts. The first 10 guns were made in May 1939, the next in July. Until the war, about 50 guns were completed. Most probably only 20-24 were fitted in the first series of rearmed tankettes TKS (possibly even a few less). In the end of 1938, one guns was mounted on a modified TK tankette, as a pattern vehicle. Further fate of this vehicle is not known. Until 25 August 1939 it was planned to rearm 16 tankettes TK, but there is no evidence that any were completed before the war (more on tankettes with cannons page).

The 20mm cannon model A was recoil-operated (short recoil). It could fire single or series shots. It was fed from 5-round box magazines (10-round magazines were in development). As a tank gun, it was fitted with a butt and a telescopic sight.

The ammunition was also developed in Poland, modeled after "long" Solothurn ammunition 20x138 mm (during trials, Solothurn bullets were used with Polish cartridges). A report from the nkm model A trials says however, that case length was 140 mm (it should be noted, that there is one report, that once in combat the captured German ammunition 2cm Kwk-38 was used, which was also identical as Solothurn). The following armour piercing rounds were developed:
- PWS - explosive round with a tracer and base fuze (APHE-T),
- PZS - ignition round with a tracer (API-T),
and practice rounds: PC and PCS (the last with a tracer).
 For AA duties there were developed: an explosive round LWS with a tracer and a sensitive fuze, practice rounds: LC and LCS (the last with a tracer), and drum magazines 15- and 100-round.
Before the war, about 90,000 AP rounds were ordered.

Gun weight - 57.6 kg, barrel weight without muzzle brake - 20.2 kg, muzzle brake weight - 1 kg.
Gun length with muzzle brake - 2015 mm (without muzzle brake - 1895 mm), barrel length with muzzle brake - 1470 mm (without muzzle brake - 1350 mm), gun width with lock handles - 202,5 mm (without lock handles - 102,5 mm).
Max. range - about 7000 m. Max. bullet velocity - 820 - 858 m/s (depending on ammunition), theoretical rate of fire - 320 rds/min.

Armour penetration:thickness / distance
Carbonated armour plates, perpendicular:20mm / 300m,15mm / 500m
Carbonated armour plates, inclined at 30°: 20mm / 100m,15mm / 400m
Homogeneous armour plates, perpendicular: 40 mm / 200m,25mm / 800m,15mm / 1500m.
Homogeneous armour plates, inclined at 30°:25mm / 300m,20mm / 500m,15mm / 600m.


37mm wz. 18 (SA-18) Puteaux

The French short-barrel semi-automatic gun Puteaux SA-18, originating from the First World War. It was simple, but quite reliable and accurate weapon, with quite high rate of fire and a flat trajectory. Its purpose was, first of all, to fight infantry and MG nests. Due to low velocity, its armour piercing capabilities were very poor. However, in 1939 this gun was able to fight most of enemy light armoured vehicles, from a short distance (up to 500m). The gun was manned by one crewman, but its maintenance was simple and jams were rare.

SA-18 gun in a Cardan rectangular mount

Calibre length - L/21. Max. rate of fire 15 rds/min, practical - 10 rds/min. A bolt opening, ejecting case and drawing a firing pin were automatic (semi-automatic operation). A mounting of a gun was flexible, and the gunner aimed it simply using a butt. It was fitted with a telescopic sight with 1.5x magnification.


In the Polish armoured weapons, 37mm wz.18 Puteaux gun was initially used in light tanks of FT-17 family (about 100-120 guns), and in 6 armoured cars Peugeot. Next, these guns became an armament of 30 armoured cars wz.28, rebuilt then to armoured cars wz.34, and of 10 armoured cars wz.29. In FT-17 tanks and cars wz.28 the guns were mounted in rectagular mountings on a Cardan joint. In armoured cars wz.29 they were mounted in round universal mountings. In 1933 -35, a few twin-turret tanks Vickers E were temporarily armed with these guns. It was also tested on a TKS tankette. Finally, guns wz.18 (in a variant SA-18 m.37) were the main armament of 50 light tanks Renault R-35 and 3 Hotchkiss H-39, bought in 1939 in France, mounted in a turret APX-R type, co-axial with 7.5 mm Mle 31 Châtellerault MG.

A photo inside a turret APX-R type of light tank R-35. From the left visible are: a telescopic sight, a breech of 37mm SA-18 gun and 7.5mm MG Châtellerault Mle 31. Click to enlarge.

The French ammunition was used, most probably:
- armour piercing high explosive round (APHE) Mle 1892
- high explosive shell (HE) Mle 1916

It is possible, that armour piercing rounds Mle 1935 and high explosive shells Mle 1937 were delivered with tanks R-35.
- AP round Mle 1892:
muzzle velocity - 388 m/s, weight - 500 g (15 g of explosive). Armour penetration - 12 mm at a distance of 0 m.
(According to source [3]: bullet weight - not known which - 560 g, velocity - 495 m/s, penetration: 12 mm /500 m. According to other source: weight 527 g, penetration: 15 mm /500 m. The data above seem most reliable, though).
- HE shell Mle 1916:
muzzle velocity - 367 m/s, weight - 555 g, explosive weight - 30 g, max. range - about 2500 m.
- HE shell Mle 1937:
muzzle velocity - 440 m/s, weight - 555 g, explosive weight - 56 g.
- armour piercing core round (APCR) Mle 1935 (according to other sources it was armour piercing round capped, with ballistic cap - APCBC):
muzzle velocity - 600 m/s, weight - 390 g, armour penetration - 21 mm at 400 m.

37mm wz. 36, wz. 37 (Bofors)

It was a licence copy of the Swedish Bofors gun, manufactured in Poland by SMPzA in Pruszków (Stowarzyszenie Mechaników Polskich z Ameryki). The gun wz. 37 was a tank variant of a towed anti-tank gun wz. 36, a standard Polish anti-tank weapon. With 300 guns bought in Sweden, the Polish Army had 1200 anti-tank guns wz. 36 (a number of Polish-made guns was also exported to Romania, Spain and Great Britain).
  The first series of 50 tank guns wz. 37 was ordered in March 1937, the second of 61 guns in April 1938. Before the war there were made 111 of them. They were mounted in Bofors-designed turrets in 108 single-turret tanks 7TP, and in tank prototypes 9TP and
10TP. It is not known, if any guns of the 3rd batch, ordered in April 1939, were completed. The guns were fitted with telescopic sights wz.37C.A. and periscope sights wz.37C.A., produced by Polish Optical Works (PZO), the periscope sight was modelled after Zeiss sight. The telescopic sight was used when the tank was not moving, while the periscope sight was used when moving. The wz.37 gun was aimed by a crank gear, and fired by a pedal.

A cross-section of 7TP turret, with wz.37 gun [source 7].

Also original AT-guns wz.36 found some use in armoured weapons. Slightly modified guns were mounted in 2 prototype light tank destroyers TKS-D. According to initial project, they could be mounted either in a vehicle, or on an original wheeled carriage, which was towed by the vehicle (the second way was dropped as impractical, and TKS-D towed an ammunition trailer instead). They were also to be an armament of a projected tank destroyer PZInz.160.

On the left: a back-door view of the 7TP's prototype 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.
 On the right: dismounted co-axial mounting of wz.37 gun and wz.30 TMG of 7TP tank.
[Photos - source 7] (Click to enlarge)

Guns wz.36 and wz.37 were semi-automatic, with a sliding block (block opening, ejecting case and drawing a firing pin were automatic). Barrel length - 1665 mm = L/45 (1736 mm with a muzzle brake). Practical rate of fire - 10 rds/min (in a tank gun it might be less, due to more difficult conditions in a tank turret).

Ammunition:
- armour piercing (APHE)
- armour piercing with a tracer (AP-T)
- high explosive - fragmentation (HE-Frag)

- AP round:
muzzle velocity - 800 m/s (Swedish data - 870 m/s); bullet weight - 700 g, explosive weight - 15 g, cartridge weight - 1450 g. Inertial base fuze.
- HE-Frag shell:
explosive weight - 48 g, impact fuse, max. range: 7100 m.

As for armour penetration, there can be different data found. Anyway, 37mm Bofors gun could destroy any armoured vehicle in 1939 from a distance below 1km, and its performance made it one of the best 37mm AT guns of that time.

Penetration according to the source [7]:

- vertical armour plate:
60mm at 300m, 48mm at 500m, 30mm at 1000m, 23mm at 1500m, 20mm at 2000m;
- hit angle 30° (plate inclined at 60° from vertical?):
40mm at 100m (this value is also given by source [6]).

Penetration according to the Swedish data and the Finnish manual:

- armour plate inclined at 30° from vertical:
40mm at 300m, 33mm at 500m, 18mm at 1000m.

Other sources give also values: 40mm at 500m; 25mm at 1000m.

47mm Vickers QF

It was the British tank gun developed by Vickers-Armstrong for export only. Primarily, it was an armament of single-turret light tank Vickers E (6-ton) Alternative B (Type B). 22 of these guns were bought in 1934 by the Polish Army, with Alternative B tank turrets. These turrets were next used to convert 22 Polish twin-turret Vickers E Type A to single-turret Type B standard.

Unfortunately, the information about this gun is scarse. Data: muzzle velocity (Armour Piercing) 488m/s, (High Explosive) 302m/s. Projectile weight - 1.5kg. Range (HE?) - up to 6km. Armour penetration: 25mm at 500m, other source: 29 mm at 1200 m inclined at 60°. Barrel length about L/18 (estimation). Ammunition: AP rounds (APHE?) and HE shells. Rate of fire up to 10 rds/min. A telescopic sight was to the left of the gun.

Vickers Mk.E Type B cross-section - the 47mm gun in a turret (based on a drawing by M. Baryatynski).


47mm wz. 25 Pocisk

This gun was designed in Ammunition Works "Pocisk" ("The Bullet") in 1925, for an infantry gun contest. It was quite good design - the first modern gun designed in Poland, but it did not enter production, because in 1930 it was decided not to equip the Polish Army with special infantry guns. Moreover, its armour penetration was considered as not sufficient. However, 4 from among several completed guns were fitted on 4 experimental light self propelled guns TKD in 1932 (built on not armoured tankette chassis). These vehicles were used in a number of Army manouvres and in Zaolzie regaining in 1938. It is not known if they were used in 1939.

A prototype of 47mm wz.25 "Pocisk" infantry gun - and a light self-propelled gun TKD (click to enlarge).

47mm wz.25 gun was semi-automatic, with a pivoting block. Max. rate of fire - 16 rds/min. Goertz panoramical sight. Elevation - in TKD: -12 +23°.

Ammunition: armour piercig high explosive (APHE), high explosive (HE) and a cannister.

- AP round:
muzzle velocity - 400 m/s, projectile weight - 2.08 kg, explosive weight - 42 g. Armour penetration: 20mm at 1025m (?).
- HE shell:
muzzle velocity - 365 m/s, shell weight - 1.94 kg, explosive weight - 128 g. Max. range 6500 m.
- cannister:
weight - 2.46 kg.

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Armoured trains' artillery:

75mm wz. 02/26 gun

The 75 mm wz.02/26 gun in armoured train "I Marszalek", before the war.

It was originally the famous Russian 76.2mm (3-inch) M.1902 cannon of Putilov Works, which was the basic Russian field gun of the World War I and of the civil war. Several hundreds of these guns were captured by the Poles during the Polish-Soviet war 1919-1921 and used as wz.02 gun. Between 1926 and 1930, about 429 wz.02 guns were modified in Starachowice Works, after which they received a designation: wz.02/26. The modified guns were fitted with a special barrel insert, so that they their caliber became 75mm, and they could fire the ammunition of the Polish standard field gun wz.1897 (Mle 1897) Schneider. Field guns wz. 02/26 were used until 1939 in mounted artillery battalions of cavalry brigades, and in gun platoons of infantry regiments. In the Polish service this gun was nick-named: "prawosławna" ("the orthodox" gun). In 1939, the Polish Army had 425 of these guns [source 8].

In the late twenties, wz.02/26 guns were introduced as the standard armament of the Polish armoured trains, replacing guns of other types, among them original guns wz.02. 25 guns were an armament of all 10 Polish armoured trains mobilized in 1939, several further guns were an armament of reserve wagons. In armoured trains, these guns were mounted in artillery turrets, on original shortened gun beds, or on naval mountings.

A number of cartridge types were used, among others:
- shrapnel wz.1897 (weight 7.25 kg),
- grenades (HE shells):
steel shell wz.15 (weight 5.225 kg without fuze, weight of explosive 0.78 kg),
steel shell wz.17 (as above: 5.97 /0.66 kg),
steel-cast iron shell wz.18 (as above: 6.375 /0.435 kg),
- armour-piercing high explosive shells wz.10 (weight 6.4 kg, weight of explosive 90g). Armour penetration about 60mm.

Gun data: barrel length 2340 mm (L/31 calibres); screw block; max. range 5000-10700 m (depending on round type); muzzle velocity - about 529 - 600 m/s; max. rate of fire - 10 rds/min; crew - 6-7 men; elevation (in armoured trains) - 11°.

More on 75mm wz.02/26 gun on a separate page.



100mm wz. 14/19A howitzer (Skoda)

The third artillery wagon of the Nr.15 armoured train, armed with 100 mm howitzer.

It was the Czech design of Skoda works. These guns started life as wz.14 (M.14) howitzers of the Austro-Hungarian army, acquired later by Poland. In the 1930s Poland started licensed production of improved variant wz.14/19P, with longer barrel, and existing wz.14 howitzers were modified in a similar way, receiving a designation wz.14/19A. In 1939, the Polish Army had 336 of wz.14/19A and 510 of wz.14/19P howitzers [source 8]. They were the basic howitzers of the Polish light artillery regiments of infantry divisions, and also the standard howitzer of the Polish armoured trains, from early 1930s. 13 howitzers wz.14/19A were an armament of 8 Polish armoured trains in 1939 (nos: 11, 12, 14, 15, 52, 53, 54 and 55). Possibly some further howitzers were used in reserve wagons.

Ammunition was two-piece. Projectile weight: 12-16 kg. Among other used were:
- shrapnels (weight 11.97-13.5 kg),
- HE shells (weight: 13.9-16 kg), among others:
shell wz.28 (weight 15.8 kg),
shell wz.31 (weight 14.4 kg).

Gun data:
barrel length - 2400 mm (L/24 calibres); horizontal sliding block; max. range: 10,000 m; muzzle velocity - 408 - 415 m/s; max. rate of fire - 8 rds/min; crew - 7; elevation: -8 +48°.



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Update history:
19. 07. 2008 - corrected and improved armoured train's artillery, added 2 photos, other minor text improvements

Sources:
1. Andrzej Konstankiewicz: "Broń strzelecka Wojska Polskiego 1918-39"; Warsaw 1986
2. Rajmund Szubański, "Polska broń pancerna 1939"; Warsaw 1989
3. Janusz Magnuski, "Pociag pancerny 'Smialy' w trzech wojnach"; Pelta; Warsaw 1996
4. Leszek Komuda, "Przeciwpancerne tankietki" in: Militaria vol.1 no.4
5. Witold Jeleń, Rajmund Szubański: "Samochod pancerny wz.29"; TBiU nr 84; Warsaw 1983.
6. A. Konstankiewicz, W. Słupczyński: "Armata przeciwpancerna wz.36", TBiU nr 45, Warsaw 1977
7. "Czolg lekki 7TP - czesc pierwsza", Militaria vol.1 No.5 - special issue
8. Andrzej Konstankiewicz: "Broń strzelecka i sprzęt artyleryjski formacji polskich i wojska Polskiego w latach 1914-1939", Lublin 2003, ISBN 83-227-1944-2



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Text copyright to Michal Derela.