Friday 30 August 2013

Vickers 6-ton Trials

If you have read the history of the T-26, you know that the tank takes its roots from the British Vickers 6-ton tank. This tank was not in demand by British tank forces, due to their mind-boggling doctrine, but was an excellent tank for its time, and widely used abroad. Here are the results of trials the USSR put it through:

"Trials happened between November 27th, 1930, and January 5th, 1931.
  1. Maximum speed:
    1. Good road: 35.2 kph.
    2. Dirt road, covered in packed snow: 30-35 kph.
    3. Off-road, covered in snow, in places up to 400 mm deep: 19-20 kph.
  2. Average speed:
    1. Asphalt or dirt roads, covered in packed snow: 27.6 kph.
    2. In a column of 3: 20.2 kph.
    3. Off road, covered in snow, up to 400 mm deep:
      1. One tank: 18 kph.
      2. Three tanks in a column: 12.5 kph.
  3. Range: Asphalt or dirt road covered in packed snow: 110-130 km.
  4. Capable of crossing five rows of two-strand barbed wire, forming a passage 3.5-5 meters wide.
  5. Shooting results: Shots were fired from the machine gun, using the optical sight, at a target 3*3 meters, at 250 meters, while moving off-road in the snow. It should be noted that shots from 18-20 kph are not indicative of the performance, due to insufficient training of the tank commander and platoon commander, as this is the first time there were shooting at a high speed. There was also no synchronization between the crew, the driver did not properly execute orders of the turret commanders. The shooting was also affected by temperature of -17 degrees.
    1. At 5-6 kph: out of 40 bullets fired, 32% hit.
    2. At 10-12 kph: out of 40 bullets fired, 30% hit.
    3. At 18-20 kph: out of 40 bullets fired, 12% hit.
  6. Conclusions:
    1. This type of tank stands out in its class for use in mechanized units.
    2. High mobility, maneuverability, agility, and other qualities are satisfactory for a light tank in mechanized units.
    3. These characteristics are accomplished by poor passive protection: armour.
    4. The configuration of the tank is accomplished by reducing convenience while servicing the motor.
    5. Shot accuracy while moving is notably high.
    6. The hull shape gives the enemy a small target.
    7. In the event of engine failure: torn gasket, torn exhaust valve, need of re-lubrication, etc. require the engine to be removed completely. In order to remove the engine, all armoured plates are removed from the inside of the tank."
RGVA, 31811-2-18

Wednesday 28 August 2013

Combat Performance of 7.5 cm and 8.8 cm Guns

I've posted tons of very technical information on the performance of various 75 and 88 mm German guns. However, all that really doesn't say much about how well these guns performed on the battlefield. Thankfully, Colonel P.S Igumnov did all the hard work for me, and all I have to do is show figures from his doctoral thesis, "Investigation of Destruction of Domestic Tanks (using the experience of the Great Patriotic War).

Here's a nifty data set, distances of penetrations from the two aforementioned calibers:

And a nicer looking version of the data, compiled by fat-yankey

The data is not surprising at all. The majority of 88 mm hits are at 600-800 meters, exactly the range at which a Tiger would be engaging a T-34 according to the Tigerfibel. The mythical 2 km shots represent a negligible amount of the total. The 75 mm caliber favours closer engagements, at about 400-500 meters.

World of Tanks History Section: Battle of Stalingrad

1. Introduction

The Battle of Moscow ended on April 20th, 1942. The German Army, whose advance seemed unstoppable, was thrown back from the capital of the USSR by 150-300 km. The Germans took heavy losses. While the Wehrmacht was still strong, it no longer had the ability to advance on all sections of the front simultaneously.

During spring mud, the Germans developed a plan for a summer offensive in 1942, codenamed Fall Blau (Case Blue). Initially, the target of the offensive were the oil wells of Grozniy and Baku, with possible further advance into Persia. Before the offensive, the Germans were going to "cut off" the Barvenkov Salient, a large foothold captured by the Red Army on the western shore of the Severskiy Donets river.

Soviet command was also gathering for a summer offensive in the Bryansk, South, and South-West fronts. Regrettably, despite the Red Army's initial successes that pushed the Germans back to Kharkov, the Germans managed to turn the situation around and deliver a crushing blow to Soviet forces. The South and South-Western fronts were weakened, and, on June 28th, Hermann Hoth's 4th tank army broke through between Kursk and Kharkov. The Germans were at the Don river.

At this point, Hitler made a personal change to Case Blue that cost the Germans dearly. He split Army Group South into two parts. Army Group A was to continue to the Caucasus. Army Group B was to march to the Volga, cut off strategic communications between the USSR and Central Asia, and capture the city of Stalingrad. Hitler wanted to take the city not only for practical reasons (the city was a large industrial center), but for ideological ones. Taking the city named after the Third Reich's greatest enemy would be a great victory for German propaganda.

2. Positions of forces and the first stage of the battle

Army Group B, advancing on Stalingrad, included Paulus' 6th Army. It consisted of 270 000 soldiers and officers, 2200 artillery units and mortars, about 500 tanks. The 6th army was supported from the air by the 4th air fleet of General Wolfram von Richthofen, consisting of about 1200 aircraft. Later, closer to the end of July, Hoth's 4th tank army was added to Army Group B, including the 5th, 7th, 9th army and 46th motorized corps. The latter included the Das Reich SS tank division.

The South-Western Front, renamed to the Stalingrad Front on July 12th 1942, had 160 000 soldiers, 2200 artillery and mortars, about 400 tanks. From 38 divisions that made up the front, only 18 were fully staffed. The rest had between 300 and 4000 people. The 8th air army assigned to the front also had a numeric disadvantage compared to Richthofen's. With these forces, the Front had to cover a defensive line more than 500 kilometers wide. The Soviet forces were further disadvantaged by the flat steppe terrain, on which enemy tanks could act unimpeded. Combined with the small amounts of anti-tank weapons, this made the tank menace critical.

The German advance started on July 17th, 1942. The advance guard of the 6th Army engaged elements of the 62nd Army on the river Chir, in the region of the Pronin settlement. By July 22nd, the Germans pushed the Soviets back 70 kilometers, to the main Stalingrad defensive line. The German high command, expecting to take the city swiftly, decided to encircle the Soviet forces at the Kletskaya and Suvorovskaya railroad stations, capture crossings across the Don river, and continue on to Stalingrad. Two strike groups have been created for this purpose, advancing from the north and the south. The north group was formed from elements of the 6th army. The south, from elements of the 4th tank army.

The north group delivered a strike on July 23rd, penetrated the front of the 62nd army, and encircled two of its infantry divisions and a tank brigade. By July 26th, forward German divisions made it to the Don. The Stalingrad Front command organized a counterattack using the front's mobile reserves, as well as the 1st and 4th tank armies, which were still incomplete. The tank army was a newly organized unit in the Red Army. It is unknown who first came up with this structure, but the first documented record of this unit type is credited to the head of GAU, Y. N. Fedorenko, in a report to Stalin. The state in which these tank armies were first envisioned did not last long, and they were seriously restructured. However, the tank armies at Stalingrad were of this specific type. The 1st tank army delivered an attack form the Kapach region on July 25th, and the 4th from the Trehostrovskaya and Kachalinskaya railroad stations on July 27th.

Fierce battles were fought on this section of the front until August 7-8th. The encircled units were freed, but a decisive victory over the German forces was not achieved. Forces of the Stalingrad Front were poorly trained, and several mistakes were made by commanding officers.

The southern offensive was stopped at the settlements of Surovkino and Rychovskiy. Nevertheless, the defensive lines of the 64th army were penetrated. Stavka ordered that the 64th army, reinforced with two infantry divisions and a tank corps, must destroy the enemy in the region of the Nizhne-Chirskaya station no later than the 30th.

Despite the fact that the units' combat ability was hampered due to being sent into battle before properly deploying, the Germans were pushed backwards, and a were in danger of being surrounded. The Germans brought fresh reinforcements into battle, and the fighting became even more fierce.

On July 28th, 1942, an event happened that cannot be left out. The famous order #227 of the People's Commissar of Defense was issued, more commonly known as "Not One Step Back". It severely increased the punishment for leaving the field of battle, introduced penal units for guilty soldiers and commanders, as well as special blocking squads: units that were tasked with detaining deserters and returning them into battle. This document, despite its cruelty, was received very positively, and improved discipline in the army.

By the end of July, the 64th army was forced to retreat past the Don. The Germans captured a series of footholds on the left shore of the river. Serious forces were concentrated in the region of the Tsymlyanskaya village: two infantry, two motorized, and one tank division. Stavka ordered the Stalingrad front to knock the Germans past the Don and restore the Don line of defense. On July 30th, the Germans attacked at Tsymlyanskaya, and by August 3rd progressed significantly, taking the Remontnaya railroad station, city of Kotelnikovo, and settlement of Zhutovo. The 6th Romanian Corps also made it to the Don at this point. The Soviets were forced to move to the left shore. On August 15th, the 4th Soviet tank army was forced to do the same, as the Germans were threatening to penetrate the front in its center and cut it in half.

By August 16th, the forces at Stalingrad retreated past the Don, and took up defensive positions in the city's fortifications. On August 17th, the Germans renewed their push, and managed to capture crossings by August 20th, as well as a foothold in the region of the Vertyachiy settlement. Efforts to throw back the Germans were unsuccessful. On August 23rd, a German force supported by aircraft broke through the defensive lines of the 62nd army and 4th tank army and reached the Volga. 2000 sorties were flown by German aircraft that day. Many areas of the city were destroyed, oil stores were burning. 40 000 civilians were dead. The enemy reached Rynok, Orlovka, Gumrak, Peschanka line. The battle migrated to Stalingrad's walls.

3. Battles in the city

When the Soviet forces retreated to the outskirts of Stalingrad, 6 German and one Romanian infantry divisions, two tank divisions, and one motorized division opposed the 62nd army. The Germans had 500 tanks, supported by at least 1000 aircraft. Stalingrad was in danger of falling into enemy hands. Stavka sent in two armies (10 infantry divisions, 2 tank brigades), re-equipped the 1st Guards Army (6 infantry divisions, 2 guards infantry divisions, 2 tank brigades), and assigned the 16th air army to the Stalingrad Front.

On September 5th and 18th, forces of the Stalingrad Front (Don Front after September 30th) weakened the Germans with two massive offensive operations, drawing away 8 infantry, two tank, and two motorized divisions. It was not possible to destroy the Germans completely. Fierce battles for the inner defensive line raged on.

Battles in the city started on September 13th, 1942, and continued until November 19th, when the Red Army began an offensive as a part of "Operation Uranus". From September 12th, the 62nd army was tasked with defending Stalingrad, under the command of Lieutenant-General V.I. Chuikov. This man, considered too inexperienced to lead before the battle, created a real hell for the enemy in the city.

On September 13th, 6 German infantry, three tank, and two motorized divisions were near the city. Until September 18th, fierce battles were fought in the central and southern parts of the city. The enemy was held back south of the train station, but the battle in the center was not as fortunate. The Germans pushed the Soviets back to the Krutoy ravine.

Especially fierce fighting for the train station took place on September 17th. In one day, it changed hands 4 times. The Germans left 4 tanks and 100 dead there. On September 19th, the left flank of the Stalingrad Front attempted to launch an offensive to take the train station, with subsequent attacks on Gumrak and Gorodishe. It was not possible to move up, but a large enemy force was held up in the fighting, which eased the job of forces in the center of the city. The defense here was solid enough that the enemy never made it to the Volga.

Understanding that the center of the city was impenetrable, the Germans sent their forces south, for an eastward strike in the direction of Mamayev Hill and the Krasniy Oktyabr settlement. On September 27th, the Soviets launched a preemptive attack with small infantry teams, armed with light machine guns, incendiary bottles, and anti-tank rifles. Fighting continued from September 27th to October 4th. These were the very same street battles in Stalingrad that freeze the blood in the veins of even the most hardened men. The two sides fought not for streets or neighbourhoods, not even for houses, but for separate floors and rooms. Hand to hand combat was as common as in the middle ages, when edged weapons ruled the battlefield. After a week, the Germans moved forward 400 meters. Everyone joined the fight: construction workers, engineers. The Germans slowly petered out. Similarly desperate struggles took place at the Barricade factory, Orlovka settlement, at the Silikat factory.

By the beginning of October, the area of Stalingrad controlled by the Red Army dwindled to the point that it could be completely covered by artillery and machine gun fire. The forces fighting in the city were supplied from across the Volga by anything that could float: boats, yachts, steamboats. German aircraft relentlessly bombed the crossings, making delivering supplies even more difficult.

While the 62nd army held and wore down the enemy, Stavka was preparing a massive offensive, aimed at destroying the German forces at Stalingrad.

4. "Uranus" and Paulus' surrender

At the start of the Soviet counteroffensive, aside from Paulus' 6th army, Stalingrad was also home to von Salmuth's 2nd army, Hoth's 4th tank army, as well as Italian, Romanian, and Hungarian forces.

On November 19th, the Red Army began a massive offensive operation on three fronts, codenamed "Uranus". Its start was signaled by 3500 guns and mortars. The barrage lasted 2 hours. In honour of this specific artillery barrage, November 19th was named "Artillery Day".

On November 23rd, the 6th army and Hoth's 4th tank army were encircled. On November 24th, 30 000 Italians surrendered at the village of Raspopinskaya. By that point, the territory occupied by the Germans was 40 km west-to-east and 80 km north-to-south. Subsequent compression of this territory proceeded slowly, as the Germans held on to every scrap of land. Paulus demanded a breakthrough, but Hitler forbade it. He did not lose hope that it was possible to penetrate the ring externally.

Erich von Manstein was tasked with the rescue mission. Army Group Don was tasked with freeing Paulus' army in December of 1942 with a strike from Kotelnikovo and Tormosina. On December 12th, operation "Winter Storm" began. The Germans did not advance with all forces. Only one tank division and one Romanian infantry division attacked on time. Two other incomplete tank divisions and some amount of infantry joined in later. On December 19th, Manstein's forces engaged Rodion Malinovkiy's 2nd Guards Army. By December 25th, "Winter Storm" was extinguished in the snowy Don steppes. The Germans returned to the initial positions, with heavy losses.

Paulus' forces were doomed. Hitler was the only person that disagreed. He was against retreat when it was still possible, and would not hear of surrender when the mouse trap finally and irreversibly clamped shut. Even when the Red Army captured the last airfield the Luftwaffe could supply Paulus' army with (as poor and unreliable as it was), he still demanded that Paulus and his men fight.

On January 10, 1943, the start of the operation to liquidate the German force began. It was named "Operation Ring". On January 9th, a day before it began, the Soviet army delivered an ultimatum to Paulus. By coincidence, the commander of the 14 tank corps, General Hube, arrived in the encirclement on the same day. He passed on the message that Hitler demands that Paulus continue fighting and that attempts to break open the encirclement will continue. Paulus followed his orders, and rejected the ultimatum.

The Germans resisted as the could. The offensive even briefly stopped between January 17th and 22nd. Soviet forces regrouped and resumed their attack. On January 26th, the German forces were cut in half. The north group was located in the region of the "Barricade" factory. The southern group, with Paulus, was located in the center of the city. Paulus' command center was located in the basement of the central general store.

On January 30th, Hitler awarded Paulus the title of Feldmarschal. By unwritten tradition, feldmarschals never surrendered. This was a suggestion from the Fuhrer that Paulus ought to end his military career. Paulus decided that it was wise to ignore some suggestions. On January 31st, at noon, Paulus surrendered. Another two days were spent on clearing out the rest of the city. On February 2nd, it was over. The Battle of Stalingrad was won.

90 000 soldiers and officers were captured. The Germans lost 800 000 soldiers and officers. 160 tanks and 200 airplanes were captured.

Original article available here.

Additionally, here is a map of Stalingrad stitched together from German aerial reconnaissance photos, provided by Rossmum. Watch out, it's 40 MB in size.

Monday 26 August 2013

S Ekranami

The "KV-1E" is a pretty well known KV-1 modification: a KV-1 with additional bolted on armour, 30 mm in the front and 25 mm on the side, to increase the armour to at least 100 mm. What is less known is that other Soviet vehicles received the same treatment.

Let's start with the T-26. A number of vehicles received this treatment both before and after the war. A large number of photographs of these tanks can be found here. A number of projects to increase the armour of the T-26 were developed in the late 1930s, but none were implemented until the start of the Winter War. Compared to the T-26's initial armour, the screens were impressively thick: up to 40 mm. The tank could withstand shots from 45 mm guns from 400-500 meters. This additional armour was attached to both the older model 1933 T-26es and newer model 1939 ones by welding and bolts. Later models used only welds to hold the armour. The additional armour of some tanks gave their turret a more polygonal shape, making them more reminiscent of later light tanks, such as the T-70. 

While a number of tanks were up-armoured at the factory to server in the Winter War (89 tanks, according to this source), a larger number received a similar treatment at Leningrad, during the siege. Here, the tank's greater mass of 12 tons did not significantly impact the performance, as the ability to resist higher caliber anti-tank artillery was more important than the ability to move quickly or over a great distance. Leningrad and field modifications of the up-armoured T-26 tank can be distinguished by a lack of movable gun mantlet. Since time was of the essence, the additional mantlet armour was stationary, and had holes cut in it for the gun, unlike the pre-war tanks, where the additional armour was attached to the mantlet.

The BT-7 also received new armour. The new screens gave it 50 mm of front armour (hull and turret), 45 mm of turret side armour, and 30 mm of hull side armour. This gave it immunity from 37-45 mm AT guns and 75-76 mm field guns. The mass increased to 20 tons, reducing the maximum speed to 45 kph. The driver's hatch had to be sacrificed. At least one vehicle was built, and took part in the parade in November of 1941.

A BT-5 also received armour screens, including the interesting sloped side armour. Not much information is available on this vehicle, aside from a quote from the order "On strengthening the armour of T-26, BT, and T-28 tanks with armour screens", where 300 T-26es, 350 BT-5s, and 350 BT-7s were to be equipped with additional armour.

Speaking of the T-28, the T-28 with armour screens is also a pretty well known modification. Initially, all T-28s were to get armour screens, but only 111 tanks actually did. Lots of photographs of these tanks are available here

I have written about T-34s with additional armour before, but a different armouring scheme was also proposed in November of 1942:

CAMD RF 38-11355-2042

Here is how Lieutenant-Colonel Shahverdyan describes his invention:

"Technical description of modernization of KV and T-34 tank armour

Modernization of a tank's armour achieves the following:
  1. Strengthens the tank's armour to resist penetrations.
  2. Increases the chance of a ricochet.
  3. Protects the tank's turret from jamming.
  4. Protects the tank's suspension.
  5. Strengthens the tank's front for ramming."
The Lieutenant-Colonel proposed corrugated armour, 30 mm thick, with the wave's peak 150 mm away from the tank's initial armour. 

Another, much larger, up-armouring was planned for the ISU-122.

"To the People's Commissar of Tank Manufacturing, Comrade Malyshev

Self propelled artillery guns ISU-152 and ISU-122, manufactured at the Kirov factory, differ in mass by 1 ton. The ISU-152 weighs 45.5 tons, and the ISU-122 weighs 44.5 tons. Despite the larger mass, the performance of the ISU-152 is identical to the ISU-122.
As such, it is possible to increase the armour of the ISU-122 within the limits of 45.5 tons.
Preliminary calculations suggest that front armour 150 mm thick and a gun mantlet 160 mm thick will not weigh more than 1 additional ton. This front armour will be able to resist 75 and 88 millimeter enemy shells from a distance of 500 meters and higher.
In order to determine the practicality of this solution, and the necessary amount of work connected with re-balancing the D-25S gun with this additional weight, I deem it reasonable for the Kirov factory to complete the blueprints for this SPG by January 15th, 1945.
After completing that task, a prototype ISU-122 with increased hull armour must be built, in order to carry out trials.

Colonel-General of the Tank Forces, Korobkov"
CAMD RF 38-11369-654

150 mm at 30 degrees is effectively 173 mm of armour! That's quite an amount, giving you a sizeable chance to resist even 88L/71 shells at nearly point blank range

Sunday 25 August 2013

D-25T Artillery Tables

Slowly but surely, I am increasing my collection of artillery tables. The latest entrant is the famous D-25T tank gun from the IS-2. Let's take a look.

The text above the table shows the direct fire distance, the distance for which the shell trajectory does not surpass the height of the target, for three target heights: 970 meters for a 2 meter target, 1120 meters for a 2.7 meter target, 1180 meters for a 3 meter target.

The columns are as follows: distance (in meters), sight settings (using two different kinds of sight scales), trajectory height (in meters), two columns for correction (for drift and wind), the amount of height a single division on the sight would change, angle of aiming, angle of falling, impact velocity, time in flight, and, finally, two columns for average deviations: vertical and horizontal. 

Nothing special, precision-wise for the BR-471B round. Average dispersion of 30 centimeters in each direction at 1000 meters is more or less consistent with previous tank guns I have shown off. The table for the BR-471 round is the same accuracy-wise. 

The direct fire distances for the HE shells are the same, but there are a lot more columns. The first six after distance are for setting up various sights. The seventh is for trajectory height. The next eight are for corrections for even more things, including atmospheric conditions and temperature. The next one is the change in distance that will occur with one one-thousandth change in the setting of the sight. Next is short bracket. Next is the aiming angle. After that, the impact velocity and flight time, same as the previous table. The remaining figures are for average deviation, but there is a new column: average deviation for distance. This is necessary for indirect fire

The high explosive OF-471 and OF-417N shells manage to be even more precise, with an impressive dispersion of 20 cm vertically and 30 cm horizontally. That is the lowest figure of any gun I have seen a table for so far.

Friday 23 August 2013

VJa 14.5 mm Autocannon

CAMD RF 38-11355-806

"To the head of the Auto-armoured-tank Directorate

On the topic of experimental installation of the VJa 14.5 mm gun into a tank

Presently, in order to increase the penetration of German tanks and armoured cars, by the order of the Command of the Command of the Military Air Force of the Red Army, we are developing the VJa gun with a breech for a 23 mm casing and a barrel for the standard 14.5 mm round, the penetration of which is increased to 90 mm due to its increased speed.
The VJa 23 mm gun is already adopted by the VVS and is in production at NKV factories. As a part of the conversion to 14.5 mm, the barrel and receiver must be altered, which can be done at the appropriate transitions, which is easy to implement in mass production.
Based on the above information, we consider it possible to install a VJa 14.5 mm gun on a tank. According to our calculations, it is possible to install this gun in a light tank. 
We ask for your decision regarding the installation of a 14.5 mm VJa tank gun on a tank on one of your tank factories.

Inventors of the VJa gun

July 28th, 1942"

The "light tank" in question was no other than the T-60 tank. Putting an aircraft autocannon on it was no new notion, as the TNSh gun it used was a modified ball turret version of the 20 mm ShVAK. However, this project was not to be. 20 days prior to this, Stalin himself put an end to the T-60 project, favouring new T-70 tanks, with real cannons on them. With APCR ammunition, those tanks could achieve as much as 100 mm of penetration, making this fancy experimental new gun unnecessary.

Wednesday 21 August 2013

BT Gun Problems

The article on the history of the BT briefly alluded to problems with the B-3 gun. I found a letter from Halepskiy to Voroshilov that talks about these problems in more detail.

RGASPI 558-2-91. January 2nd, 1933.

"In my letter, based on the information given to me by comrade Belov and director of the Mariupol factory comrade Radin, I wrote that 800 BT turrets are to be built for the B-3 37 mm gun. The UMM is scheduled to produce no more than 375 of these guns in 1931-32, and told KhPZ, as well as the Izhor and Mariupol factories that no more than 350 turrets should be built for these guns. In the same letter, I warned comrade Pavlunovskiy that the order for 800 turrets was made without agreement from the People's Commissariat of the Army and Navy, and asked him to resolve this issue. I also informed comrade Pavlunovskiy that UMM considers it possible to only build 350 BT tanks with 37 mm B-3 guns, exactly the number established by the government. 

Comrade Pavlunskiy did not reverse his decision. Using my position as a member of Kuibishev's commission, I added this issue to the list of issues raised at the meeting.

Comrades Ordzhonikidze, Pavlunovskiy, Tuhachevskiy, and Egorov were present. They heard me out, but did not come to a conclusion. Comrade Ordzhonikidze claimed that I was incorrect, and it was necessary to build 800 turrets. I replied that there will only be 352 of these guns made, and then production will be stopped to focus on the newer 45 mm gun. It is unreasonable to produce 800 turrets for this gun. Comrades Tuhachevskiy and Egorov agreed with me. Comrade Budnyak confirmed that 37 mm B-3 guns are ending their production run. No final decision was made.


When Kuybishev Jr.'s commission investigated this issue, comrade Pavlunovskiy and my assistant, comrade Bokis, were present. I was away on a business trip to Leningrad.

The commission, despite protests from comrade Bokis, decided to solve the issue of overproduction of the B-3 turret by disarming 340 T-18 tanks and mount their 37 mm Hotchkiss guns on BT tanks. At the same time, arm the T-18s with two DT machine guns. At the end of the year, replace the 37 mm Hotchkiss guns with 45 mm guns. 


In order to complete this task, we first need a factory to figure out how to convert the B-3 turrets for the Hotckiss gun, and then convert T-18 turrets for machine guns. There is currently no such factory, and no existing factory can take up the task, as KhPZ and Voronezh are overloaded and are already behind schedule. Additionally, more armour plates must be produced, and this will impact work being done by armour production factories. Thirdly, this process will take 6-7 months, considering that this issue was raised since December 4th by factories, but no work has been done on it since. Finally, the Hotchkiss gun has poor ballistic qualities, and penetrates less armour than a machine gun with armour piercing bullets.

In my opinion, this re-armament is fruitless, and has no purpose from any viewpoint. In this time, 45 mm guns will start production. It is necessary to produce turrets for the BT that are compatible with the 45 mm gun in 1933."

Monday 19 August 2013

Soviet Partisans vs Tanks

When you have no anti-tank weapons, any tank is a great threat, even an obsolete one. Theoretically, Soviet partisans were helpless against new tanks being sent to the front and obsolete PzI and PzII tanks sent specifically to hunt them. However, the Partisan's Companion, a booklet sent to partisans to teach them how to organize an effective resistance, has some ways out of this situation.

IX. Destroy enemy tanks!

During battle with a tank, remember:

A brave man has nothing to fear from tanks. The more bravery you meet an enemy machine with, the easier it is to destroy it. Seek out fascist tanks and destroy them. A tank's engine is its source of movement. Destroy the engine and the tank will stop. The engine works on gasoline. Stop its delivery and the tank will stand still. If the tank still has gasoline left, try to ignite it, and the tank will burn. The tank's turret spins, while the main gun moves vertically. Try to jam the turret to deny the enemy the ability to aim. The tank's engine is cooled by taking in air from vents. All moving connections and hatches also have holes. If you pour in flammable fluid, the tank will burn. In order to look around, there are viewing ports and instruments behind hatches. Cover the ports with mud and shoot at the hatches with any weapons to try to jam them. In order to traverse rough terrain, the tank has tracks. Try to take out the tracks or the drive wheel. When the tank's crew is evacuating, take them out with whatever you have: bullets, grenades, bayonets.

The weaknesses of tanks

The crew cannot hear due to how loud the tank is. The crew can see poorly due to the difficulty of using viewing instruments, especially while moving. It is difficult to fire from a moving tank due to the amount of shaking. Effective fire can only be performed from a distance of 400 meters. In order to fire accurately, the tank will have to stop briefly.

Weak points of fascist tanks

The tracks and leading wheels
View ports
Bottom and roof
Engine compartment
Attack these sections. Study figure 141 carefully, and remember where you have to shoot or throw grenades and flammable fluids to disable the tank.

Figure 141: Tank weak spots. The boxes pointing to the turret say “sniper fire”. The one pointing to the engine compartment says “flammable fluid”. The ones pointing to the tracks and roof say "bundles of grenades".

Be ready to meet the tank

The sooner you notice it, the easier it will be to destroy. During the day, use your eyes more than your ears. During the night, the sound of a tank's motor can be heard up to 900 meters, 450 if the wind is towards the tank, 1500 is the wind is towards you. The sound of a moving tank travels even further. A tank has appeared. Do not fret and run around from place to place. Conceal yourself using the environment. Hide in a ditch, hole, trench, pit or even behind a hill or bush. Be ready to meet the tank and destroy it using any available equipment. Learn where the Fascist tanks are located. Approach them unnoticed and destroy them.

Bullets and tanks

Using a 7.62 mm rifle or regular machine gun, you can destroy tankettes, light tanks and armoured cars of the enemy. Open fire from 100-300 meters. Fire at the view ports of the tank. Accurate file can spray the crew with molten lead.
Especially accurate shooters (snipers) shoot at the viewing instruments and weapons of the tank. Using large caliber machine guns, open fire at the gas tanks and sides of the tank. Armour in those places is usually thinner. Heavy tanks have thicker armour. Use large caliber machine guns to fire at the viewing ports and weaponry.

Grenades against tanks

Destroy fascist tanks using grenades thrown from 25-30 meters. The best device to use in this case is the anti-tank grenade (see page 132). Throw it from cover. Aim for the tracks, leading wheels, roof of the engine compartment and turret. If you don't have special anti-tank grenades, throw grenade bundles. Here is how you make one. Five grenades, loaded and with the safety on, tie together with twine or wire: four grenades with handles in one direction and one in the other (fig. 142). 

Figure 142: A bundle of five grenades.

Take the bundle by the handle of the fifth grenade and throw it at the tank. That grenade explodes first and will trigger the rest of the bundle.
You can make the bundle from three model 1933 grenades. Take off the casing and screw off the handles from two of the grenades. Throw the bundle while holding the third grenade's handle. After throwing the grenade, duck and take cover.
Antitank rifles and rifle grenades are also useful weapons against tanks. To see how to use them, look at pages 157 and 160.
If possible, sneak up to the tanks and attach explosives or anti-tank mines to weak points, and destroy the fascist tanks with explosions.


Prepare ambushes on forest roads. Partially saw some trees on both sides of the road. Leave about one quarter of the trunk intact. Saw at the height of 50-80 cm. Topple the trees across the road, preferably across each other, so their tops point towards the enemy. Have 15 meters of obstructions. Hide. Destroy stopped tanks using any methods available.
If you have antitank mines of explosives, lay them at the obstruction. This makes it impossible to clear the obstruction. If the crew leaves the tank to clear the road, kill them with rifles or grenades. In case enemy tanks try to go around, set up mines at the side of the road.

Tank Traps

Dig a trench 3 meters in depth (fig 144). The width of the trench should be 5.5 meters at the top, 1.5 at the bottom. Construct a cover on top. For a foundation, use four moderately thick logs, two at the edges of the trench and two in the middle. On top of those, lay twigs and branches. Cover them with a thin layer of soil. People should be able to walk on top of the trap, but tanks should fall though. Carefully disguise the trap. Remove excess dirt, even out the ground, lay down some grass. During the winter, cover the trap with snow.
Stay close to the trap. Destroy the tank with grenades or bottles. Shoot at the crew as they try to leave.

Figure 144: Tank trap.

Combat against armoured cars

The same tactics apply against armoured cars. Throw grenades at the bottom of the car, leading and rear wheels and the mesh on the turret. Throw flammable fluid bottles at the front of the car, where the motor is. Remember that armoured cars have armour thinner than 10 mm. It can be pierced with AP rounds from machine guns and rifles. Open fire from less than 300 meters. When facing heavy 4-axle cars, fire at the viewing ports from close range.
When fighting a truck, shoot at the driver, throw flammable fluid at the radiator or the driver, throw grenades at the wheels. If the truck is full of enemy soldiers, use an antitank grenade so they don't get away.

Wire against motorcycles

An enemy motorcyclist can be dismounted by putting up wire across his path. Choose a sturdy tree in a forest. Tie one end of the wire about 1 meter above the ground. Toss the wire across the road and stand near a tree across from the first one (fig. 145). When you hear the enemy approach, wrap the wire across the tree and hide. The motorcyclist will hit the wire and fall off. Kill or capture him.

Figure 145: Fascist motorcyclist hits the wire.

Winter obstructions

Snow obstructions: During the winter, fight tanks with snow. Build obstructions given a thickness of snow of at least 25 cm. The height should be 1.5 m, length – 4 m (fig 146). A tank that hits this obstruction will get stuck and the tracks will lose traction. It is better to make these traps after it gets warmer. In order to hold the snow in place, use straw or twigs, poking them into the snow. Make these traps close to hills, in lowlands and clearings in forest or bushes. It's good to make several of these, especially close to roads.
It makes sense to combine this trap with mines and tree obstructions. Place the mine diagonally on a solid base. The mines will explode under the tank.

Figure 146: Diagram of a snow obstruction.

Icing: Slopes steeper than 15 degrees should be covered in water. The resulting ice hill will cause the tank to lose traction. You can do this when it is colder than -5 degrees. It is more effective at very low temperatures. Use this tactic on banks of rivers and streams.

Ice holes: Make holes in ice on rivers and lakes. The width should be 4 meters, the length, 5-6 meters. Cover the hole with branches and twigs and cover it with snow. Such a hole will last a long time and will not be noticed by moving tanks. This is a very effective technique. Remember to keep a distance of 2-2.5 meters between the holes.

Hunting group

Fight tanks in groups of 4-6 people. Two or three throw grenades or bottles. The rest open fire on the evacuating crew.
In case of an ambush, it is good to position some people on the trees. If making an ambush in a narrow place where the cars cannot go offroad, destroy the front and rear cars first. The resulting traffic jam will make it easier to destroy the rest.

Here's an instance of partisans being useful against tanks using an unconventional method.

"At an enemy crossing over the Chudokoye lake, in the Pnevo region, quadrant 542, partisans sawed 300 logs into three pieces."

Sunday 18 August 2013

SKB-2's Experiments

"Experimental Developments of the SKB-2 at the Kirov Factory:
  1. Installation of the 122 mm artillery system (M-30) into the regular KV-1 turret with a new armour scheme. Approximately 50 shells fit in the tank. A prototype is built at Uralmash, and will be tested in early January 1942.
  2. Installation of the 85 mm anti-aircraft artillery system into the regular KV-1 turret, with approximately 80 shells that fit in the tank. A prototype will be ready by January 10-15, 1942.
  3. A raiding T-34 is being developed, with a top speed of 70 kph, with lightened hull and suspension, as well as larger gas tanks for increased range.
  4. A tankette called "Rage of the People" is being developed, 2.5 tons in mass with 20-25 mm of armour, powered by two S-65 tractor engines, with a crew of 2 and machine gun armament.
  5. A pipe-less radiator made from sheet steel was tested separately, and soon will be tested on a car. There is no reason why we cannot mass produce this radiator.
  6. A heater for tanks that moves the air heated by the engine to the crew compartment. At a temperature of -25 degrees, the compartment is kept at 12-18 degrees. This invention is already in production, and will be installed on all vehicles starting in January 1942.
  7. Replacement bearings for idler wheels, road wheels, and suspension components with sliding bearings and ball bearings of local production.
Also, work is being done on replacement of steel casings of final drive gears and other non-worn components with cast iron, replacement of highly hardened 33xSA and 38xSA steels with high-carbon steel, stamping tracks with two halves in order to free up the heavy presses, cast tracks, and idlers with welded on cheeks for the track tension mechanisms."

CAMD RF 38-11355-870

The first item is quite obviously the KV-9, a KV-1 with the 122 mm U-11 howitzer. The second item is the somewhat lesser-known KV-10. Shashmurin's ridiculous tankette (who needs a tankette in 1942?) and the much more interesting raiding T-34 (I wonder if they saved the armour thicknesses) do not appear anywhere else. 

Friday 16 August 2013

World of Tanks History Section: T1 Cunningham

At the start of the 20th century, no one could have predicted that tanks would become an army's main strike force. Tanks were expected to support infantry, cover advancing soldiers with their armour, and help them suppress the enemy. Fortifications that were too tough for the tanks would be destroyed by artillery, shooting from prepared positions.

In the middle of the 1920s, American high command admitted that the M1917 tank currently used by the army was obsolete, and created a plan for the development of a superior fighting behicle. In 1924, the head of the commission was sent to Rock Island to aid in the creation of a light tank, no more than 5 tons in mass.

In cooperation with engineers from the Cunningham company (famous for its tracked tractors), the military, armed with experience of their foreign colleagues (mostly the British engineers responsible for the Medium Mk II), came to the decision that the classic tank layout is not ideal. After uniting American and foreign solutions, the T1 tank prototype was born. Tests of the chassis showed that it needs to be heavily reworked; the "tractor past" was no longer enough. The new high-tech chassis let the tank accelerate up to 29 kph, a record among similar vehicles. Sadly, this could not be repeated in combat conditions, as the chassis performed poorly on cross-country terrain, bomb craters, etc.

The chassis consisted of 16 small diameter wheels, 8 per side, with spring amortization, 6 supporting rollers, a front idler wheel, and a rear drive wheel. The tank hull was made of partially welded and partially bolted together armour plates 10-15mm thick. The transmission and 8 cylinder gasoline engine were in the front. The engine was capable of 132 hp at 2600 RPM. The tank had a 58.5 gallon (221.5 liter) gas tank, and a 4 speed gearbox. The engine was started electrically. The driver's compartment was united with the fighting compartment, in the back of the tank. The T1's crew consisted of two members: the driver and commander (who doubled as a gunner).

Armament was installed in the turret only. It consisted of a 37 L/50 M5 37mm gun, with 104 shells (some sources claim 80), and a coaxial M1919A4 Browining machine gun (with 3000 rounds). Despite the small caliber of the main gun, the muzzle velocity of 777 m/s allowed it to penetrate any currently fielded armour at 1000 m.

The T1 light tank was worked on through 1926, and a prototype was handed to the military in early 1927. Field tests were disappointing. The prototype had poor mobility, could barely cross a trench two meters across, and the stiff suspension made firing on the move difficult. After modifications, the T1E1 was accepted by the military in 1928, as the M1. 4 tanks were sent to the 4th Tank Company (Fort Meade, Maryland), where they tested extensively through 1930. After these tests, the T1E2 modification was equipped with a more powerful engine, a modified turret (without a slanted armour plate) and thicker front armour. The tank was later equipped with a longer 37mm gun.

The last modification was the T1E3, with a spring suspension and a long barreled gun. Nevertheless, due to many design drawbacks, mass production of the T1 light tanks never got off the ground. The only known T1E1 is displayed at the Aberdeen tank museum.

Original article available here.

Wednesday 14 August 2013

German Armour Quality

During WWII, the relations between Britain and the USSR have been quite close. Aside from material aid (the British sent Lend-Lease tanks and equipment, the Soviets sent captured German tanks and their own samples), the two countries exchanged intelligence. Here is one of many such exchanges, from CAMD RF 38-11355-2704:

"Tendencies in the manufacturing of German armour plates (excerpts from the report prepared by the Head of the Main British Tank Development Directorate)

The testing of a Tiger tank recently brought to England showed a deviation from typical German armour protection techniques. None of the armour was surface hardened. The hardness on the Brinell scale is as follows:
  • Thin horizontal plates (26 mm thick): 298-343
  • Thick nearly vertical plates: 257-310
The fact that the armour is no longer surface hardened, and has a relatively low Brinell hardness, is very important. It must be noted that this change coincides with the appearance of new German heavily armoured tanks: Tiger, Panther, Ferdinand. Until now, no German tank had armour thicker than 50 mm.

The deviation from existing practices is explained by the following reasons, or their combination.
  1. Economic reasons. It is very possible that the very amount of armour overloaded the German capacity to manufacture it, and Germany was forced to utilize heavier manufacturing, usually tasked with manufacturing simple armoured plates. There might be a shortage of equipment capable of processing thick armoured plates.
  2. Mechanical finish problems. The three aforementioned vehicles have interlocking armoured plates to increase the strength of the welds. Regular step connections were preserved. The combination of these two connections reduced the ability to produce a large number of armoured hulls. Perhaps the softer plates were introduced to remedy these problems.
  3. Ballistic factors. The three aforementioned vehicles were built for the purpose of long ranged combat. It is possible that the enemy introduced softer armoured vehicles knowing that the Allies use armour piercing capped shells. Use of these shells against soft armour is suboptimal. If soft armour continues to be used, we must explore the question of ballistic caps. However, it is necessary to collect more information, as this armour could still be surface hardened. 
It is necessary to examine a Panther tank and perform experiments on armour of Tiger tanks built later than the one mentioned in this report."

The report came out in January of 1944, so not many Tigers were built after that. The Americans, meanwhile, tested the armour of the Panther. Their findings spoke rather poorly of German manufacturing. Their findings were the same as what any of my readers have already seen: German armour is of poor toughness, and their welding seams have a tendency to burst under pressure.

Monday 12 August 2013

Soviet Supertank: Osokin's Tank Cruiser

We already established that CAMD accepts some pretty crazy stuff. It's not all spherical tanks, though. Some of it is jetpacks, or tank catapults, or electrical armour. Some of it is this thing.

CAMD RF 38-11350-1356

Oh yes. It's like that crazy fake KV-VI project, except someone actually thought that this was a good idea. Someone that should know better, too. Osokin wasn't some kind of peasant, he was an Engineer-Lieutenant-Colonel. Of the VVS, though, so hopefully his airplane engineering was at least a little bit more realistic. Let's look at the statistics of his beast.
  • Combat mass, with armament: ~270 tons
  • Armament and ammunition:
    • guns: 2*152 (160-200 shells), 5*76 (650-800 shells), 2*23 (1200 shells)
    • machine guns: 3*12.7 (4500 rounds), 14*7.62 (26460)
  • Armour thickness (in various places): 40-125 mm
  • Engines: aircraft M-30 or M-40
  • Total horsepower: 4000-6000 hp
  • hp/ton: 13.3-22
  • Area of tracks in contact with ground: 43.4 meters squared
  • Ground pressure: ~0.7 kg/meter squared
  • Maximum speed: 36-40 kph
  • Minimum speed: 4.2 kph
  • Performance:
    • elevation: up to 40 degrees
    • vertical obstacle: up to ___ meters
    • crossable trench: 9 meters
    • fording depth: 1.8 meters
  • Fuel capacity: 8400 kg of diesel
  • Operational range: ~600 km
  • Crew: 30
  • Amount of transportable infantry: 50
Water hazards can be crossed using attachable pontoons of the Epron type (soft or rigid).

Well, it looks like he stapled 4 T-34 model 1940s to two T-100-Zs and called it a day. Oh, also, this monster is 21.45 meters in length and 9.7 meters in width. You would think that an air force officer would be aware of what a juicy target this would represent. I guess that's what the 5 AA guns are for. The Red Army was also unimpressed with the project, and it disappeared into the archives.

Giganaut made a 3D model of this thing, and made it sillier in the only way possible.

Add some Katyusha rockets, because why not!

Sunday 11 August 2013

CAMD Contents

People might be curious, what does CAMD store, exactly? I've posted all manner of things. Ballistics tests, scientific papers, purchase orders, phone call transcriptions, meeting minutes, the list goes on. The answer to that is: everything. CAMD stores literally every single document that stopped being useful. Here's an example.

Even I can't read that. Thankfully, there is a handy transcription! 

"Comrade Fedorenko

I write this in the dark, the lights are off, the bombing is very heavy. Send tanks, we get some, but not enough. I ask you to arrange an apartment in Moscow for my wife.

KVs get hammered by heavy artillery. T-34s behave better in battle. We are running low on AP.


Thursday 8 August 2013

World of Tanks History Section: T-60

The Great Patriotic War that started on June 22nd, 1941 made serious changes to the development of Soviet tank manufacturing. The first days of the war saw the cutting of a series of development programs, and even a number of vehicles already in mass production.

According to the decision of the USSR SNK, on June 25th, 1941, Ordzhonikidze factory #37 NKSM in Moscow was to cease producing half-armoured T-20 "Komsomolets" artillery tractors and amphibious T-40 tanks on August 1st. Instead, they were to assemble T-50 tanks. The Ordzhonikidze factory in Podolsk would supply hulls and turrets. In total, up to 50 organizations in Moscow and the Moscow area were tasked with producing components for the T-50.

The decision to replace the T-40 with the T-50 seemed logical and reasonable. Amphibious scout tanks were not produced in massive quantities. They were meant to supplement more numerous armoured cars. The amphibious tank with only 13 mm of armour and a DShK machine gun seemed inferior to the T-50, with its thick, anti-gun armour and 45 mm cannon. The child of factory #174 was meant to also replace the T-26, and become one of the Red Army's most numerous tanks. By June 1941, production began. Amid the harsh losses of the start of the war, it seemed that T-50s would be needed in huge numbers.

The conditions for the T-50 were perfect, but an order is one thing, and reality is another. Factories were not ready to produce it. The tank ended up being complicated even for #174. Due to this, the start of production was delayed by several months. Factory #37, which previously assembled amphibious tanks from automotive components, had an even more difficult time. The Moscow vehicles did not exceed 5 tons, while the new Leningrad tank weighed 14 tons. The V-4 diesel engines posed another problem. Factory #75 NKSM (Kharkov) did not set up their production. As a result, the chances of mass producing the T-50 in 1941 dropped to zero. If factory #37 followed orders and dropped production of the T-40, no new light tanks would be produced at all. Thankfully, the management of factory #37, especially its construction bureau, headed by Nikolai Aleksandrovich Astrov, fully realized the capabilities of the factory. In order to assemble a 14 ton tank, the tools of the factory must be upgraded, and there was a lack of heavy cranes to do so. Formally, factory #37 did not refuse the order to produce a T-50, and was even developing an amphibious tank on its chassis. At the same time, in utter secrecy, the factory's construction bureau was developing a tank that was a simplified version of the T-40. In July of 1941, a letter was sent by N.A. Astrov and the factory military representative, V.P. Okunev. This letter, addressed to Stalin, described the impossibility of producton of the T-50 at factory #37, and suggested a replacement that could be produced in large quantities: a small tank based on the T-40.

The letter was delivered to Stalin on that same night, and piqued his curiosity. The next morning, the deputy SNK chief and People's Commissar of Medium Manufacturing Malyshev arrived at the factory. After evaluating the situation and hearing the claims of the project initiators, he wrote a letter to Molotov on July 14th, in which he approved the project.

The new tank, indexed T-60 (or 030 in internal factory communications) was a non-swimming version of the T-40. Turns out that T-40 hulls and turrets manufactured in Podolsk were very complicated, especially turrets, made entirely out of cemented armour. A large amount of hull defects delayed production. A switch to homogeneous armour partially solved that problem. A simplified hull was necessary, especially with the GKO order #222 "On manufacturing of 10 thousand light tanks", which increased the amount of factories that produced the T-60.

On July 23rd, NKSM order #360ss ordered factory #37 to develop a simplified T-60 hull and turret. Two days later, the factory had a technical meeting on the issue of GAZ and HTZ producing T-60 tanks.

Instead of a simplified T-40, HTZ and GAZ received blueprints for a radically different vehicle. Meanwhile, factory #37 was producing the initial T-60, due to production quotas and an overload of the Podolsk Ordzhonikidze factory. The result was a tank called the T-30, which is worthy of its own article. The "030" was not called "T-60" for long. At the end of July, the tank was first officially referred to as T-30, and by the end of August, it is widely referred to as such. The tank produced at HTZ and GAZ had the factory index "060".

The index T-70 was used rarely, but enough to confuse some historians. The tank is called "T-60 with a simplified hull", "T-60M", or just "T-60". The last name was firmly attached to the new tank by the fall of 1941, but even in 1942, some factories still call it "T-70" or "T-60M".

It is interesting to note that the army accepted both 030 and 060 before construction of experimental prototypes. With 030, it is not as surprising, since it was effectively a T-40 with a simplified armour scheme. Development of blueprints for this tank took two days. Despite the fact that the technical task of designing a simplified hull and turret was issued on July 23rd, work on the 060 started on July 20th.

Astrov's construction bureau set a world record on the speed of developing the tank: last blueprints were completed on July 28th. The entire documentation cycle took a week. This is confirmed by dates on the blueprints.

The layout of the 060 is interesting enough to be given some details. It largely copied the T-40, but with several changes that had to do with a not so pleasant story, namely with the engine. In October of 1940, the People's Commissariat of Aviation Manufacturing took away GAZ's GAZ-11 and GAZ-202 engine manufacturing plant, in order to produce M-105 aircraft engines. GAZ was forced to put on pause a number of vehicles that used the GAZ-11 engine, including the T-40 tank. In the end of 1940, the idea of using a ZiS-16 engine (ZiS-5 forced to 85 hp) and its diesel version, the D-7. One tank was sent to ZiS, but resulted in an unsatisfactory outcome. The new engine was too large. By June of 1941, issues with the GAZ-202 engine were resolved, but it seems that the head of the hull group, A.B. Bogachev, resolved the crisis, despite the hull being 15 cm shorter, the tank fit not only the stock GAZ-202 engine, but, with some modifications, the ZiS-5 engine.

The story of 030's and 060's armament is also interesting. The initial plans called for the same armament as the T-40: a DShK with a coaxial DT. Plans had to be changed, since the DShK's manufacturers (mostly the factory #507 in Lopasnya) could only produce several hundred of these guns per month. On July 23rd, 1941, the deputy People's Commissar of Defense G.I. Kulik assembled a meeting on the armament of the T-60. A replacement was needed for the DShK, and it was quickly found.

In 1936, an automatic 20 mm cannon was developed by the OKB-15: ShVAK (Shpitalniy-Vladimirov, aviational, large caliber), which was the first mass produced example of this weapon type in the USSR. The gun was unified with the large caliber machine gun of the same name. By the start of the Great Patriotic War, the gun was widely used on fighters and ground attack aircraft. Its ball turret version could easily be mounted on a tank.

On July 26th, GKO order #289ss "On the armament of the T-60 tank" was issued. According to the order, it was to be armed with OKB-15's ShVAK 20 mm autocannon. In September, it received the index of TNSh/ShVAK model 1941.

When order #289ss was issued, a tank version of the ShVAK did not yet exist. The first prototype was installed in the T-40 (serial number 11726), and was tested between August 7th and 10th of 1941. Elements of the wing and turret versions of the gun were used, which allowed to mount the gun without developing radically new components. The gun sight remained the same: TMFN (telescopic, Maron-Finkelstein, machine gun). The only difference was a new scale on the sight.

On July 30th, before the gun was even tested, GAU was ordered to produce a number of ShVAKs, optics, and 15 millon shells. On August 3rd, the order was increased to 15 million for factory testing and 35 million for the army. The real picture was far less optimistic: on September 17th, GAU reported that it could only manufacture 30 000 shells that month. On the next day, after personal attention from the deputy chief of the council of the People's Commissars, L.Z. Mehlis, the People's Commisar of Ammunition P.N. Goremykin extended the promise to 30 000 shells for HTZ, 20 000 for GAZ, and 50 000 for #37. 3.5 million shells were to be produced in October. The order for factory #37 was mostly theoretical: T-30s were armed with DShK machine guns until the beginning of October.

According to plans, factory #37 was to produce 030s from August 1st, and HTZ and GAZ were to produce 060s from August 15th. Factually, the only hull assembled on time by the Ordzhonikidze factory in Podolsk was a 060 prototype hull made from mild steel. By the middle of August, Lening factory #69 (Krasnogorsk) produced only 25 TMFP sights, and Kirkizh factory #2 (Kovrov) produced only 15 TNSh. Factory #37 began building an experimental 060 on August 17th. The turret used was a T-40 one, with a DShK (in theory, the machine gun was never installed). This tank was assembled to familiarize GAZ with production of the 060. Astrov and Okunev personally drove it to Gorkiy, after which they returned to factory #37.

GAZ was a reasonable choice for the T-60. The Molotov Gorkiy Automotive Factory was one of factory #37's main partners for the T-40 tank. The Kharkov factory that was meant to be the main manufacturer of the T-60 was a whole different story. At the start of June of 1941, the construction bureau of the Scientific Auto-Tractor Institute (NATI, today NAMI) developed an armoured tractor in partnership with HTZ. The vehicle was indexed HTZ-16, based on the heavily modified chassis of the SHTZ-NATI tracked tractor. On July 20th, 1941, before the construction of a prototype, GKO order #219ss ordered 2000 armoured tractors from HTZ. GABTU understood that the HTZ-16 was a temporary measure, and could not be a fully fledged fighting vehicle. On the same day, they assigned HTZ to produce the T-60.

The time spans and volumes in order #222ss were unrealistic. Technical documents were to be sent by the construction bureau of factory #37 on July 27th. The first blueprints made it to HTZ on July 28th, but most of the documentation arrived only on August 10th. By August 16th, the QA standards still have not arrived to HTZ, nor did the list of components for spare parts and toolboxes.

Aside from a lack of hulls, HTZ had another problem. The T-60 was a "foreign" project, and the workers were not very enthusiastic about producing a small tank. By the middle of August, only 6 people were assigned to the T-60 project. This was explained by a lack of staff. A number of blueprints received from #37 were reworked to suit HTZ's needs, which also took time. A series of components, including the optics and tool attachments, were reworked to be compatible with the HTZ-16. In short, HTZ and its suppliers gave minimum priority to the T-60 project.

HTZ's management tried as they could to keep HTZ-16 in production. Its removal necessitated interference from the top. The ferocity of this fight can be seen in the report of military engineer 3rd class Kulikov, senior engineer of the 3rd department of BTU KA, compiled in the first half of September of 1941.

"The parallel production of HTZ-16 and T-60 is planned until the second half of September (17.9.41). The production of the HTZ-16 chassis is done using the tractor conveyor in the main plant, while production of the T-60 is planned for the middle of nowhere, on a temporary conveyor. Until Malyshev arrived, the workers were of the opinion that "maybe the T-60 will be cancelled". After he chased them around for a bit, there were changes. The plants paid devoted more attention to the T-60. Until then, the tank was classified, so none of the workers knew what the factory would produce."

On September 13th, 1941, almost a month after the planned production date, the first T-60 was assembled at HTZ, using a hull and turret produced at the Voroshilov factory. At the time, there were 12 sets of hulls and turrets, from 3 different suppliers. In September, only 7 tanks were assembled and sent out, which equaled the amount of available engines.

On September 20th, the Germans approached Kharkov, and establishments in the city began evacuation. HTZ began preparing on September 17th. The factory was to be evacuated to Stalingrad. They did not have time to evacuate completely. Germans storming the city captured equipment and several T-60 hulls.

For the next few months, GAZ remained the only factory capable of producing T-60s.

Original article available here

Wednesday 7 August 2013

On Zimmerit

Most people that have read about WWII German tanks, or have even seen pictures of them, probably know about Zimmerit. It was a coating applied to vertical surfaces of German tanks to do...well, something. On paper, it was supposed to protect against magnetic mines, but let's look at how effective it actually was. First up, the Soviets' discovery of Zimmerit, in January of 1944.

"From the 5 knocked out Tiger tanks and 15 PzIV tanks I have examined, I have established the following:
  1. All Tiger tanks have their turret sides, upper and lower sloped front plates, side, and overtrack screens covered in a cement-coloured substance, 2-4 mm thick. The substance is applied in ridges.
  2. Out of the 15 PzIV tanks, two of them have their turret screens covered in this substance.
  3. Upon analyzing the substance, it was determined that it does not ignite. We have examined a tank that burned, and the substance remained. It was only darkened. When the substance is placed in hot water, it does not dissolve, but becomes softer. It reminds me of caulk, but it is neither that, nor cement. Neither sand nor clay are evident. We need to submit it to laboratory analysis.
Conclusion: I believe that this substance is used to guard the tank from incendiary bottles, and also serve as winter camouflage, due to the gray colour.

The substance was removed from knocked out tanks.
  1. Burned tank (darkened colour)
  2. Knocked out, non-burned.
  3. The substance was scraped off with a knife from the tank's sides."
CAMD RF 38-11369-419

Let's see what lab analysis says.

"To investigate, we have been supplied with two samples: one 12 grams, one 7.7 grams, 19.7 grams in total. The sample is complicated in shape, and, photographed in full size, looks like this: 
<Photos missing>
The bottom side of the sample, meant to face the metal, has a smooth, polished surface. Externally, the sample is dark-gray-brown, light, has small pores, and is rough on the top side. 

The micro-structure sample consists of a gray-brown opaque substance, inside of which red-gray-brown polarizing organic substances can be seen. 

Inside of these organic substances, there is a large amount of angled fragments and grains, 0.01 mm to 0.1 mm in size. "

I'm going to skip the chemistry (partially because I am not a chemist and cannot vouch for the accuracy of the translation). 

  1. The ceramic substance is a paste, which includes 53% barite, 16-17% quartz, and 27% organic matter. 
  2. The melting point is 1100 C.
The small amount of the sample (about 20 grams) does not allow the examination of the organic substance, or experimentation with its effect when exposed to burning gasoline or incendiary fluid. 
The substance's parallel fluting, low melting point, high porousness, etc. lead me to believe that the main purpose is the concentration of incendiary fluids and their extinguishing by the means of the melting of the ceramic paste. "

CAMD RF 38-11355-2219

Of course, the lab analysis doesn't say anything about its magnetic properties, so maybe it still worked in that regard? Well, there are plenty of Zimmerited up tanks in museums. Yuri Pasholok, who is actually allowed to touch them, performed an experiment.

Hm, no dice. It still looks really cool on scale models, though!

Monday 5 August 2013

Artillery and High Explosives

Most battles are not won with tanks against tanks, they are won by tanks skillfully supporting infantry. I have written in depth on AP performance of various guns, but AP is useless against enemy infantry. This article will talk a little about the effectiveness of HE and indirect fire artillery.

Let's take a look at a good illustration of the explosive force of an artillery shell: the crater it forms. When the shell's detonator is configured to explode after the shell impacts the ground, instead of in the air, it can make a pretty impressive hole.
Figure 88: craters formed by HE shells of various calibers.

The HE effect of a 76 mm gun was considered enough for infantry support (T-28 and Matilda CS had 76 mm guns, for example), but as you can see the hole it makes is quite small. A hole from a 122 mm HE shell is large enough to use as a trench. A hole from a 152 mm HE shell is large enough to stand in. A tank that comes across such a crater would have a difficult time crossing it.

The HE effect by itself is quite unlikely to have an effect on enemy infantry or fortifications. Artillery relies on the effects of shrapnel to get the job done. The shrapnel effect of a shell is measured by a rectangle inside which at least 50% of the targets are hit. Here are such rectangles for several Soviet guns.

Shrapnel effects of 152 mm, 122 mm, 107 mm, and 76 mm HE shells. Shot direction is from left to right.

As you can see, the shrapnel flies out to the side more than it does to the front or the back of the shell. Increasing the caliber increases the width, but not the length, of the rectangle. A 122 mm HE shell fired from an M-30 howitzer hits only 5 meters further than a shell fired from a ZiS-3 76 mm gun, but at twice the width. 

A data sheet on various 45 mm shells gives a 10 meter radius for its high explosive fragmentation shell (strange, given that this is usually a rectangle). It is listed as producing 150 fragments. Another data sheet on experimental guns lists the data for the 95 mm gun (450 fragments), 100 mm AA gun (300 fragments), 107 mm mountain howitzer (450 fragments, 3 meters cubed crater) and the 107 mm corps gun (800 fragments, 3 meters cubed crater). 

If you're shooting at a tank with an AP shell, you have to be very precise. Realistically, shots are limited to several hundred meters with WWII era sights, maybe a kilometer or two if you are in a defensive position and have measured out the distances to various landmarks. Various objects blocking your path can limit that distance even further. Indirect fire artillery has no such problems, since it can fire over the objects, and cover hundreds of square meters with their shrapnel, instead of just one point.

Accuracy for a 76 mm model 1942 gun (ZiS-3) at full charge and 122 model 1938 howitzer (M-30) using the first charge.

As you can see, at a range of several kilometers, the dispersion is quite high. A long barreled gun, like a ZiS-3, has a high shell velocity. It is more accurate than a short barrel howitzer (8 meters of width-wise dispersion at 3 km, compared to 12 meters for the M-30), but its flat trajectory results in more length-wise dispersion (192 meters at 3 km for the ZiS-3, compared to only 152 for the M-30). The flat trajectory is important for an anti-tank gun, however. If you are shooting at a target at a distance that is close enough, the trajectory of the shell will not surpass the height of the target, and you will hit even if you estimated the distance incorrectly. The higher the shell velocity, the flatter the trajectory, the further away the target can be while you are still capable of taking advantage of that effect. A shell travelling with a higher velocity is also carrying more kinetic energy, and is thus more capable of penetrating enemy armour.

The curved trajectory of the artillery shell was used by SPG crews in combat. Nikolai Konstantinovich Shishkin, an ISU-152 commander, recalls one such instance: "One battle was memorable. Three tanks of the advance guard left the forest and went up on a hill, where they were shot by a Tiger. There was no way to go around that clearing, and the brigade commander told me: "You are a beast-killer? Go destroy that tank." My SPG moved forward, arrived at the base of the hill, and slowly climbed up it. I climbed out of the hatch and stood up. I saw a German tank, its rear pushing against a large tree. The Tiger shot. The wind from the shot nearly dragged me out of the hatch. While I thought what to do, he sent one or two more shells my way, but missed. Only a section of the casemate was sticking out, his trajectory was flat, he could not hit me. What do I do? If I go forward, I will die. I noticed a bush on the hill. Looking through the gun barrel, I instructed the driver to move the tank so the bush lined up with the tree the enemy tank was under. I replaced the gunner. The bush is in my sights. I move the gun barrel to where the enemy's tank should be. There are a million calculations, but I spent less time making them than I spent telling you about it. Fire! I climb out, the Tiger's turret is lying next to it. Direct hit!"