Saturday 30 November 2019

From Medium Assault Gun to Medium Tank Destroyer

Development of armoured vehicles in many nations proceeds in parallel. A clear example of this is the creation of German and Soviet medium SPGs. Initially, Soviet SPGs were built as tank destroyers. Later, under the influence of the German StuG III Ausf. B, the medium assault gun program was launched, which gave birth to the SU-122. By this time, the Germans had modernized the StuG III and transformed it into primarily a tank destroyer. This SPG was known as the StuG 40. In the USSR this process took longer, as there was no gun to combat German heavy tanks until the spring of 1943. That is when the SU-85 appeared, the most numerous Soviet medium SPG used in the war.

Thursday 28 November 2019

Up-Armoured T-34s

"Changes and simplifications of the hull and turret

On November 25th, 1941, the factory moved to a simplified hull. The mechanical cutting of the rabbets was simplified. The stamping of the lower rear plate (part 34.29.007) was also simplified. The full album of bluprints and technical requirements were sent out in the first few days of February.

According to the decree of the Committee of Defense the factory should have began building tanks with applique armour on the hulls and turrets by January 15th, 1942. In practice the first hull with applique armour was produced on February 25th, and the first turret on February 21st. In total there were 80 hulls and 109 turrets built with applique armour.

Wednesday 27 November 2019

Situational Awareness

"Instructions for tank watchers
  1. Tank watchers are selected from each battery to warn about the approach of tanks. They are placed in important directions no closer than 800-1000 meters to their positions.
    The tank watchers are subordinate to the battery commander and battery duty officer. 

Tuesday 26 November 2019

British Demo

By the summer of 1941 the British were still struggling to equip their army with modern anti-tank weapons in the face of a German invasion, which was considered all but a certainty. This rush resulted in a number of weapons, from more conventional anti-tank cannons to rifle grenades and bombards. The comparison of the weapons' effectiveness is fairly predictable.

Monday 25 November 2019

Tanks Review

"Exchange of experience in using tank weapons in the Patriotic War

The use of tanks in battle, especially in the winter offensive of 1943, showed several peculiarities of using tanks in battle, their advantages and disadvantages.
  1. Typical distances for firing from a T-34 tank from standstill in defense or ambush is 1000 meters. When firing on the move or from short stops during offensive action the distance is the same.
    The practical rate of fire of the 45 mm gun is 3-4 RPM. For the DT it is one disk (63 rounds) per minute. From the 76 mm gun it is 16-17 RPM. In a cohesive crew the radio operator can help hand ammunition into the turret without being distracted from his work.

Saturday 23 November 2019

Long Awaited Tank Destroyer

History often moves in a spiral. The story of Soviet medium SPGs illustrates this fact well. In the summer of 1940, when development of SPGs on the T-34 chassis began, a tank destroyer was one of them. In the spring of 1942, the concept of the SPG changed, and the SU-122 was born. However, in May of 1943 a mobile means of defeating enemy tanks in the medium weight category was needed. On August 8th, 1943, more than three years after the request for a medium tank destroyer came through, the SU-85 was finally accepted into service with the Red Army. How well did Soviet industry deal with the vehicle that came to replace the SU-122, and how did it perform the tasks given to it on the battlefield?

Thursday 21 November 2019


Checking for tiny inaccuracies to detect forged documents is a pretty common phenomenon. Soviet counterintelligence had it down to an art. Forged documents confiscated from captured spies were analyzed for more signs to be used in the future.

"Party membership booklet: bright red cover with barely noticeable stripes. Rough and blurry font. The staples are made from stainless steel. The photo is printed on glossy paper."

Wednesday 20 November 2019

Industrial Accident

"Unscheduled report of an extraordinary event
Unit: GBTU Scientific Research Proving Grounds
Region: MVO
Event: wound during trials
Time: 10:00 August 8th, 1944
Location: shooting range of the NIBT Proving Grounds, Kubinka station, Western Railroad

Rank and position
Year of birth
Social status
Party affiliation
Place of birth
Nature of wound
Sergeant Loader
Toldykin, Fedor Pavlovich
7 grades
Kolkhoz farmer
Sorochkinsk, Chkalov oblast
Ragged forehead wound
Sr. Sergeant Gunner
Butorov, Ilya Innokentivich
5 grades
Bysherovo, Buryat Autonomous Soviet Socialist Republic
Minor head bruise
Description of the event:

On August 8th, 1944, at 10:00 when testing the effect of the D-25 122 mm gun (#266-44) installed on an experimental ISU-122 #249 against armoured hulls, the gun fired unexpectedly when loaded during the fourth shot, as a result of which the recoil of the gun wounded the loader Sergeant Toldykin (ragged forehead wound) and gunner Senior Sergeant Butorov, who received a minor bruise on the forehead."

Tuesday 19 November 2019

Detailed Trials

"Approved by the Commander of Artillery of the 38th Army, Major-General of Artillery Likhachev
June 31st, 1944

Plan of firing trials demonstrating penetration ability against enemy T-4 and Panther tanks held by the 9th Guards Independent Kiev Order of Lenin Order of the Red Banner Tank Destroyer Artillery Brigade of the Supreme Command Reserve, as an element of the 38th Army

Held on June 4th, 5th, and 6th, 1944

Objective of the firing trials demonstration:
  1. To illustrate to the NCO and private ranks the effectiveness of various types of shells fired from domestic weapons against enemy tanks.
  2. To establish the penetration of weapons and the best distance from which to fire.
  3. To inspire confidence in the power of our artillery against tanks.
  4. To demonstrate the weak points of enemy tanks.
  5. The demonstrate the effectiveness of dense fire of the small arms of an anti-tank battery against enemy submachinegunners that are advancing on the observation post.

Monday 18 November 2019

Experimental Work at Factory #183 March 1941

"To the Chief of the 3rd Department of the BTU, Military Engineer 1st Class comrade Afonin

Summary report of experimental work performed at factory #183 in March 1941
  1. Trials of cooling fans: three types of cooling fans entered trials.
    1. 1st variant: instead of blade supports special ribs were used. A vehicle with this fan travelled for 800 km. Trials will continue in April.
    2. 2nd variant differs from the production type only in the riveted rim that is the same as the BT-7M type. A vehicle with this fan travelled for 400 km. rials will continue in April.
    3. 3rd variant: production fan attached to the flywheel with a friction clutch to slip in cases of rapid changes of RPM in the driveshaft. A vehicle with this fan travelled for 80 km. Trials will continue in April.
  2. Trials of the constant mesh gearbox were completed. This gearbox shows no advantages over the production type, and the top speed in 4th gear dropped by 5 kph, which is not desirable. There were also a number of defects found in several parts. It is pointless to implement this design into production.
  3. New types of cast driver's hatches with different types of thermal treatment were tested by fire. One type showed good results in terms of ballistic resistance. The decision to put it into production is being made by the BTU.
  4. Trials of a new type of turret ring with a different bearing runner to tighten tolerances. Trials showed that tolerances are tighter, but the turret can jam. Work on other variants is being performed.
  5. 8 types of air cleaners were produced. One of the types showed the best results (95% clearance) and was sent to Leningrad for government trials.
  6. Reinforced Hadfield steel tracks were produced and tested. The assembled tracks made it to 2500 km after which the pin eyes were severely worn and the tracks began to break, the same thing as with production tracks.
  7. Major modernization of the T-34: the model is complete. The design bureau is producing blueprints for the experimental design.
Military Representative of the GABTU, Military Engineer 3rd Class, Alekseev"

Saturday 16 November 2019

A Barrel Too Long

Rapid growth in power of tank and SPG guns continued throughout WWII. Designers of some nations achieved the increase in firepower through a harmonious increase of gun caliber and barrel length. Other schools of design preferred to keep the caliber, but significantly lengthen the gun. The second approach was very common for German armoured vehicles. This decision had both positives and negatives. It turned out to be not so simple to install long guns on medium tanks. The Panzer IV/70 is a good example of this. An attempt to create a more powerful variant of the Jagdpanzer IV gave the tank destroyer both new abilities and serious problems.

Thursday 14 November 2019

Pistol Power

Conservative elements within the tank corps favoured the Nagant M1895 revolver. It was relatively simple and could be fired out of a smaller pistol port than the TT. However, the Nagant took much longer to reload and could not use submachinegun ammunition in a pinch.

"For ISU-122 crews it is desirable to have a TT pistol, since the long loading time for Nagant revolvers puts the crew into a critical position. The limited amount of ammunition in a revolver causes frequent reloads. There is also much more ammunition for a pistol available inside the vehicle."

Via Andrei Ulanov.

Wednesday 13 November 2019

Small Arms

"August 8th, 1942

To the artillery quartermasters of the 124th and 125th Tank Battalions

I report to you the supply of 7.62 mm rifle cartridges and F-1 grenades carried in KV, T-34, T-60, and T-40 tanks for precise inventory.

Total MG ammunition
Ammunition by type
F-1 grenades
Light bullet
AP-I bullet
At the same time, I instruct you that AP-I ammunition should be loaded in magazines separately, not mixed with ammunition that has light bullets. Magazines with AP-I ammunition must be specially marked. Check how magazines were loaded in your units and load AP-I ammunition separately.

Report on execution of this order to the artillery supply department of the brigade by 16:00 on August 9th, 1942

Artillery quartermaster of the 112th Tank Brigade, Intendant 3rd Class, Tomilin"

Tuesday 12 November 2019

On to Tallinn

"Award order
  1. Name: Gorban, Vasiliy Moiseyevich
  2. Rank: Major
  3. Position and unit: commander of the 2nd tank battalion, 152nd Leningrad Independent Tank Brigade.
  4. Year of birth: 1916
  5. Nationality: Ukrainian
  6. Party affiliation: VKP(b) member
  7. Participation in the Civil War and subsequent action in defense of the USSR or in the Patriotic War: in the Patriotic War since June 22nd 1941, Leningrad Front
  8. Wounds and contusions in the Patriotic War: wounded twice lightly in 1941, once heavily and once lightly in 1942
  9. In the Red Army since: 1937
  10. Recruited by: career officer
  11. Prior awards: Order of the Red Banner, Order of Aleksandr Nevskiy, Order of the Red Star, Defense of Leningrad medal.

Monday 11 November 2019

7.5 cm KwK 42 Penetration Table

I've posted a number of these diagrams before, for instance here is one for the Pak 40. The set of images for the more powerful KwK 42 is unfortunately incomplete and only available in low resolution, but I am including it for completeness sake.

The Valentine is not surprising at all. The armour piercing ammunition can penetrate any surface from up to 2000 meters. HE can knock off the tracks.

Saturday 9 November 2019

First Try at a Medium Tank

To a casual observer, German tank industry was like a jack in a box. 15 years after the end of WWI it suddenly sprang to life and began to crank out world class designs. However, there is no such thing as miracles. In addition to German specialists like Joseph Vollmer and Otto Merker who worked abroad, Germany had its domestic tank program. It was conducted in secret and birthed some very unconventional designs. One of them was the Grosstraktor, a medium tank that became the culmination of German tank building of the 1920s. It was the first step on the way to the PzIV, the most numerous German tank of WWII.

Thursday 7 November 2019

Small Arms Feedback

"HQ of the 27th Rifle Division
Dept 1
November 14th, 1945

To the commander of the 132nd Rifle Corps

I present my notes and conclusions on infantry weapons, ammunition, and preparation of infantry based on experience in the Patriotic War of 1941-45.
  1. Notes on design.
    1. TT model 1930 pistol: has design defects. The center of mass is bad (almost in the center of the pistol), it must be closer to the handle, like the Borchardt-Luger pistol. It is desirable to reduce the mass to 800-850 grams, change the shape of the pistol grip to make shooting more comfortable, and increase the angle between the barrel and handle.

Wednesday 6 November 2019

Finnish Zimmerit

"Copy from a copy
For service use only
Translated from Finnish

Methods of combat against anti-tank magnetic charges

The British, Americans, and also the Russians use magnetic charges, especially against tanks and cars. They are supposed to stick to metal including painted metal or armour.

Report: this is likely a device of British origin, shaped like a half-cylinder 14 cm in length made of artificial materials and filled with explosives. The flat half has 4 magnetic poles. The curved half has an 8 cm deep slot for the fuse and detonator. The fuse is held in place with a cap that screws in.

The knife-shaped delayed fuse is 11 cm long and 1 cm in diameter. Two captured delayed fuses show that they cam go off in an hour or in 3 days. It is possible that other time settings exist.

Tuesday 5 November 2019

Lessons Learned

To Comrade Beria
January 27, 1944

Based on the recommendations given by the commander of the 3rd Ukrainian Front, Army General comrade Malinovskiy, we report that:
  1. Item 1 in comrade Malinovsky's letter proposed installation of spaced armour 30-50 mm thick on the SU-85 and SU-122 SPGs.
    We consider that it would be unacceptable to install 30-50 mm thick spaced armour on the SU-85 and SU-122 SPGs on the T-34 chassis due to excess weight and overloading of the front suspension, which would radically reduce the lifespan of the transmission and running gear.
    An experimental SPG with a 100 mm gun is being built which will have 75 mm of front armour. Trials will show how feasible this undertaking is.

Monday 4 November 2019

Quality Control

"American Embassy in Moscow, Military Mission 
January 13th, 1944

To the Tank Directorate
M4A2 Medium Tank

For your information, we attach the aforementioned list of difficulties encountered by our personnel with M4A2 tanks of the latest type. We also send you methods of resolving these issues.
  1. Turrets of many tanks are poorly fitted, therefore turning them in order to fire on the move is difficult. This usually happens due to incorrect installation of the turret ring and due to incorrectly assembled liners of the traverse mechanism. There should be a liner between the mount of the case and the turret wall. The thickness is chosen such that the space between the gear teeth is minimal, 0.002"

Saturday 2 November 2019

Heavy Tank, Italian Style

In the mid-20th century heavy tanks were a sign of membership in an elite club of tank building nations. Many nations attempted to make these tanks, but failed. Even if a heavy tanks was made, it did not always make it to the war, like the American Heavy Tank M6. Only four nations mass produced heavy tanks that made it to the battlefield: USSR, Germany, Great Britain, and Italy. The British Churchill was officially an infantry tank, and the Italian Carro Armato P 40 was only heavy on paper. The Italians never even got to use their tanks in battle, as they fell to the Germans.