Friday 30 September 2022

Not Quite a Swallow

 An attempt to "speed up" the Soviet KV-1 heavy tank in March of 1942

Tanks getting heavier during production is a normal phenomenon. Several factors are at play here. One is that requirements for protection increase over time. This is the primary factor for increased mass. Growing mass is also often a consequence for increased requirements for armament. This is usually not a huge increase, but can result in a weight gain of a ton or two. Simplification of the design, especially in wartime, also plays an effect. The T-34 is a typical example. The tank's battle weight was on the order of 27 tons in 1941. The start of the war and subsequent evacuation to the Urals resulted in a large number of simplifications. The T-34 ended up using a large amount of cast components that were much heavier than rolled ones. The tank's mass crossed the 30 ton mark in 1943, but it gained neither better armour nor better armament.

Wednesday 28 September 2022

Pz.Kpfw.IV vs StuG

 "Top Secret

Inspector General of the Tank Forces
#046/44 Top Secret

June 26th, 1944

Copy 1 out of 5

Notes on the report to the Fuhrer

Replacement of Pz.Kpfw.IV tanks with L/48 and L/70 assault guns.

1) Tactical-technical data

The 75 mm L/48 gun with the model 1939 armour piercing shell can penetrate all known types of English, American, and Russian tanks from medium distances of 600-1200 meters (including the English Cromwell tank, see attachment #1).

Monday 26 September 2022

Big Gun for a Big KV

ZIS-6 and other 100-107 mm tank guns developed in 1941

Vasiliy Gavrilovich Grabin is one of the best known Soviet gun designers. It just so happened that design bureaus under his direction created the most common tank and divisional guns used by the Red Army in the war. Grabin rose to fame as an artillery designer in the second half of the 1930s. He first created the F-22 and F-22 USV guns, then the F-32 and F-34. Far from all products developed at factory #92 went into mass production, but that was a typical scenario. The most important thing was that Grabin's designs were often better than its competitors. Factory #92's design bureau has no equal in 1940-1942. Their F-34 gun became the T-34's main weapon, and a variant of it called ZIS-5 became the main gun of the KV-1 in the fall of 1941. The Red Army's main towed gun was the ZIS-3, a grassroots initiative that could be used both as field artillery or an anti-tank gun. As an anti-tank gun, it was only beaten by another of Grabin's creations, the ZIS-2. The Central Artillery Design Bureau created on Grabin's initiative began to lose ground to factory #9's design bureau, but nevertheless the S-53/ZIS-S-53 was the T-34-85's main gun. The TsAKB was also responsible for the BS-3, another combination anti-tank and field gun. The BS-3, ZIS-S-53, and ZIS-3 still fight in distant corners of the world.

KV-2 with a ZIS-6 at the Gorohovets ANIOP, June 1941.

Factory #92 was working on a whole family of guns in early 1941, both towed and tank. They included the main character of this article: the 107 mm F-42 gun, later renamed to ZIS-6. Unlike most of factory #92's designs, this one was a grassroots initiative. However, a proposal to develop a 107 mm gun with the ballistics of the M-60 came about in June of 1940, and not from Grabin. In March of 1941 the ZIS-6 became relevant to a tank other than the KV-2. The gun became necessary for a whole number of new tanks that entered development that spring. Rumours and omissions are common when discussing the history of this gun, so let's fill in the gaps.

Friday 23 September 2022

The First Firebreathing KV

The USSR was the first country to mass produce flamethrower tanks. Initially these were chemical tanks, whose primary purpose was to deploy chemical weapons. Nevertheless, the KhT-26 chemical tank accepted into service in the summer of 1932 was already a dual purpose vehicle. It could still deploy chemical weapons, but now its main weapon was a flamethrower. The KS-2 flamethrower developed by the Compressor factory was the first mass produced tank flamethrower. The pneumatic system could spew fire 30-45 meters away, not too far, but not too bad for a first try. The KhT-26 was the USSR’s first mass produced flamethrower (chemical) tank. The KhT-130 on the chassis of the T-26 tank with a cylindrical turret and KhT-133 based on the T-26 with a conical turret and turret platform followed. The T-46-1, the T-26’s replacement, was also supposed to be a chemical tank, but it never went into production. The flame throwing range gradually increased, but still was not enough. Other platforms were considered for flamethrower tank production, but the chemical BT never took off.

Wednesday 21 September 2022

45 mm gun vs Pz.Kpfw.IV Ausf.E

Photo #64: Penetration of the front hull, 50 mm thick, from a range of 50 meters (I).

Monday 19 September 2022

The Tank's Hidden Foe

On paper, German anti-tank rocket launchers were a weapon of unimaginable terror for enemy tank crews. An infantryman with a light anti-tank weapon capable of penetrating up to 200 mm of armour could be lurking behind every corner and in every window. This weapon was powerful enough to destroy any Allied tank. What was the real effectiveness of the Panzerfaust and Panzerschreck, and what did the Allies do to protect themselves from it?

Friday 16 September 2022

Friday 9 September 2022

Swords to Plowshares

 "Report to Marshal of the Soviet Union N.A. Bulganin


November 17th, 1947

Armoured and Mechanized Forces are in possession of 1185 foreign tanks, broken down as follows:

  • 889 functional (including 756 M4A2 and 54 Valentine)
  • 146 need medium repairs
  • 57 need major repairs
  • 93 are unserviceable

Tuesday 6 September 2022

A Round Too Long

Attempts to create fixed ammunition for the 122 mm D-25 gun in 1944-45

It is no secret that the firepower of tanks in WW2 increased dramatically. Armies of the world began the war wither with 37-47 mm long barrelled guns or 75-94 mm short ones. Some tanks even had armament composed only of heavy machine guns or small autocannons. Firepower of heavy tanks increased the most noticeably, particularly in 1943. German heavy tanks settled on the 88 mm caliber, the Americans focused on 90 mm guns with ballistics of the M3 AA gun. The USSR also initially chose an AA gun, an 85 mm one. However, there was a huge leap forward in the summer of 1943. The design bureau of factory #9 under the direction of F.F. Petrov developed the 122 mm D-25 gun by combining the D-2 122 mm gun (its ballistics were very close to those of the A-19) and the cradle of the 85 mm D-5T-85 gun. After trials in the Object 240 experimental tank, it was accepted into service as the IS-2 (IS-122) on October 31st 1943.

Friday 2 September 2022

Tsyganov's Armour

Additional armour developed by Engineer-Major N.F. Tsyganov, author of the BT-IS and BT-SV

Plenty of tank designers were among those who were repressed in the 1930s. 1937-38 was the most difficult period where a number of designers and military personnel linked to tank production were either executed or ended up with lengthy prison sentences. However, history sometimes lumps the latter in with the former. For instance, A.O. Firsov (chief designer of the T2K design bureau at factory #183) died in 1943 of natural causes and was not executed as is sometimes written. There are even more surprising cases where the allegedly executed party remained working at their old place of employment. For instance, Nikolai Nikolayevich Kozyrev, the chief tank designer at factory #37 and author of the T-37 and T-37A amphibious reconnaissance tanks, would have been very surprised to find out that he was executed. Kozyrev didn't even leave factory #37. It's true that N.A. Astrov replaced him as the head of tank design, but Kozyrev remained in important positions. By the fall of 1941 he occupied the post of chief engineer of factory #37. After evacuation to Sverdlovsk he continued working on tanks.

Tsyganov's BT-IS tank. The drives to the wheels can be seen. The BT-IS was an 8x6 vehicle, i.e. 6 of the wheels were powered.