Armoured Confusion: Mid-war

The history of Soviet wartime armoured vehicles bore several misconceptions. There are many reasons for this. A number of myths came from a lack of information. Sometimes historians' own guesses that had little to do with reality were interpreted as fact. Unfortunately, the authors of some myths are still considered experts to this day and these exercises in fiction are still cited as fact. Initially the author planned on two articles dedicated to misconceptions about the Great Patriotic War, but there were too many misconceptions for 1942-1943, and so the second article won't be the last.

Cancellation of the SG-122

"To the State Committee of Defense, comrade V.M. Molotov

January 3rd, 1943

GOKO decree #2429ss issued on October 19th, 1942, which began domestic SPG development, also approved production of 120 SG-122 122 mm self propelled howitzers on the chassis of the captured German Artshturm at factory #592.

Factory #592, due to a lack of necessary organization, failed to complete this task, and produced only 6 SPGs, fulfilling a separate GAU order.

Unlucky SPG from Mytishi

On December 2nd, 1942, GKO decree #2559ss "On organization of production of self propelled guns (SPGs) at the Uralmash factory and factory #38" was signed. It became the final point in the long history of Soviet medium SPGs, which started out as tank destroyers, but turned into assault guns in the spring of 1942. On GKO's orders, the U-35, designed by the UZTM design bureau, was put into production, even though it had not even entered trials yet. This kind of order is explained by the desperate need for these kind of vehicles in the Red Army. Interestingly, instead of Sverdlovsk, Mytishi could have become the center for medium SPG development. The SPGs designed at factory #592 were, at the very least, no worse than those designed in Sverdlovsk.

SG-122 Conversion

"To the Chief of the Red Army GAU, Colonel-General comrade Yakovlev

Report on the SG-122 SPGs

In December of 1942, factory #40 produced 20 SG-122 SPGs on the chassis of German PzIII and StuG vehicles. Production was later stopped due to defects of the gun mount.

Of the overall number produced, 12 SG-122s were passed on to equip the 1435th SPG Regiment. During fighting on the Western Front, all 12 SG-122s were disabled: of them, 3 were lost irreparably and 9 need factory repairs. Out of those that need factory repairs, 6 vehicles arrived at factory #37 on February 8th, 1943.

SG-122: Assault Gun on a Foreign Chassis

Work on SPGs, especially heavy ones, stopped in the USSR after the start of the Great Patriotic War. This was largely caused by the fact that the factories were busy with other orders. In addition, many factories were evacuated eastward. Only light SPGs were put into production at the start of the war, and these were largely improvised.

Meanwhile, due to the number of factories that switched from making artillery tractors to tanks, the artillery branch was forced to revisit SPGs towards the end of 1941. Experience gained in battle and a number of other factors meant that the new generation of SPGs that was built in 1942 was radically different from pre-war designs. This is especially true for medium SPGs, which became assault guns instead of tank destroyers. The SG-122 was one such SPG, built on the chassis of a captured German SPG.

PzIII Shortage

"June 20th, 1942

To the Deputy People's Commissar of Defense and GABTU Chief, Lieutenant-General of the Tank Forces, comrade Fedorenko

Moscow, 2nd NKO building

An experimental SPG on the chassis of a captured German StuG SPG, equipped with a 122 mm divisional howitzer mod. 1938 "M-30" was built according to orders from the Artillery Committee by factory #592.

Artillery Committee Conclusions on the SG-122

"April 6th, 1942

Conclusions

On the draft project of the 122 mm SPG called "122-SG"

1. Contents of the project

The GAU Artillery Committee received a draft project of a 122 mm howitzer on the chassis of a captured StuG from the OKB-16 independent design group. The proposal was met with a question (letter #537868, March 17th, 1942) regarding the utility of replacing the German 75 mm gun with a domestic 122 mm M-30 mod. 1938 howitzer.

The NKV Technical Council had a positive reaction towards this proposal and offered the OKB-16 independent design group, led by comrade E.V. Sinilshikov, to execute the project.

Ergonomics of the SG-122 Draft Design

An image of a tank with measurements? You know the drill, let's compare this baby to the Soviet ergonomics guide!

Right off the bat, the height of the fighting compartment isn't enough for the loader. The manual recommends 1750-1800 mm, but the included diagram shows that this requirement wasn't met by any WWII era tanks. The production version of the SG-122 had a 170 cm tall fighting compartment, which was almost enough. The 1620 mm provided by the SG-122 draft is still a lot, beaten only by the Churchill, the Cromwell, and the PzIII.

The line marking the bore axis is also visible in the image, which makes it easy to figure out its height: 1260 mm. This is rather high. At this height, the manual suggests that the breech should be horizontal, pointed towards the loader. However, since the M-30 howitzer uses a screw breech instead of a sliding breech as assumed by the manual, this advice doesn't really apply.

Via Yuri Pasholok.

A Case for the SG-122

"An explanatory memo attached to the SG-122 self-propelled 122 mm howitzer

In March of 1942, the Separate Design Group organized by the NKV Technical Council in order to work on self propelled guns designed an SPG consisting of a mod. 1938 122 mm howitzer on top of a captured German StuG. This project, indexed SG-122, was approved by the Technical Council and Artkom.

An Artkom plenum that was examining issues of self propelled guns in early April of this year also remarked that it is necessary to rapidly begin production of the SG-122.

The People's Commissar of Armament, comrade Ustinov, signed order #217s to organize the production of experimental prototypes at factory #592 and the creation of a special design bureau.

...

Specifics of the self propelled SG-122 gun

1. High firepower: The 122 mm shell and its HE action combined with sufficiently high muzzle velocity (512 m/s) and high rate of fire (10-12 RPM) make the SG-122 a powerful weapon against enemy pillboxes, field fortifications, machinegun nests, and other fortifications.
2. Protection: The use of an armoured casemate results in less casualties compared to towed artillery.
3. Mobility: It is possible to follow tank units and open fire at fortifications from a short range in order to destroy them and clear the path for tanks.
4. Versatility and agility: The SPG can fire when stationary and on the move, quickly shift fire, turn on its tracks, and aim approximately using a simple aiming device for the driver (made of two planks). Variable propellant loads and high angles of elevation make indirect fire possible, making it possible to destroy closed or far away targets, as well as hull down targets.
5. Stability: The mass of the SPG is sufficient to fire without deploying trails.
6. Maneuverability: The small increase in mass (2 tons) does not reduce maneuverability characteristics.
7. Protection of the crew from fumes: When shooting at a high rate of fire, gas masks can be worn, connected with extended hoses to the outside air, bypassing chemical filters, which can be switched on in case of a gas attack. Trials show that wearing gas masks has almost no impact on the rate of fire. If the hatches are open or the engine is running, it is possible to fire quickly without gas masks.
8. Use of 9-R Radios and PTU-4 bis.

The SPG has sufficient room, dimensions, and an unoccupied crewman (vertical loader/radio operator).

Re-arming StuGs can be done at the factory with readied components and cut armour (from captured or destroyed tanks) in 10-12 days. 

Re-arming will not take a large amount of effort, as all components are simple and are mostly produced with cutting or electric welding. The M-30 howitzer is installed with few changes (including the stock sight). 

As the design bureau of factory #592 has demonstrated, it is possible to similarly re-arm A-34 tanks with a 122 mm howitzer. 

More detailed data regarding the SG-122 can be found in the manual and factory trials report.

Chief engineer of factory #592, Lomakhin

Chief designer of factory #592, Sinilshikov"

CAMD RF 38-11355-693

Making the SG-122

"Contract

Mytishi, September 7th, 1942

Factory #592, hereafter referred to as "supplier", represented by factory director comrade D.F. Pankratov, acting according to the factory regulations on one side and the Artillery Committee of the Red Army GAU, hereafter referred to as "customer", represented by ___________ acting according to ___________ on the other, compose the following contract:

1. Contract purpose

The supplier will produce five new SG-122 self propelled howitzers and refit one prototype according to factory #592 SKB blueprints, with the installation of a radio, tools, and spare parts on each. The customer will accept the self propelled howitzers and pay for the cost of their production.

2. Technical requirements and acceptance

The self propelled howitzers are produced in groups, according to the following blueprints:

• Group 03: #100441
• Group 04: #100437
• Group 05: #100421
• Group 06: #100453
• Group 07: #100464
• Group 11: #100463
• Group 16: #100422
• Group 28: #100455

Tools and parts are included with the vehicles according to the list in the SG-122 manual.

Guns and radio stations are provided by the customer by September 10th, 1942, free of charge. Additionally, the customer provides the following for every radio set:

• One TPU-3 set with a cable. Note: if the original cable is missing, it can be substituted with a 7-strand ATSOE type cable, 10 meters in length.
• 4-6 shielded cable, 15 meters in length.

Installation of the radios is done by factory #592 according to the technical specifications of the Red Army NIST and directions of GAU KA.

StuG and PzIII chassis are supplied to factory #592 by GABTU through GAU KA, repaired and suitable for service, with shielded electrical cables, free of charge, by September 10th, 1942. Note: the PzIII tank is modified into a StuG.

The Red Army GABTU issues armoured plates necessary to produce SG-122 vehicles  to factory #592 from its repair bases, free of charge. Note: cutting and shaping armoured plates is performed by factory #592.

Produced self propelled howitzers must pass gunnery and mobility trials as outlined by the GAU KA program. The customer provides ammunition and fuel for these trials. 

The final acceptance of the self propelled howitzers will be done by a GAU representative, who will compose an acceptance contract for every howitzer.

3. Price and totals

The cost of one self propelled howizer is 45,000 rubles. The refitting of the prototype costs 10,000 rubles. In total, the order is for the sum of 235,000 rubles.

4. Deadlines

The deadline for the order is September 1942, conditional on the delivery of all components by the customer by the specified dates. Payment for the order is done according to rules of the Credit reform.

5. Penalties

In the event that the order is not filled in time, the supplier pays a penalty of 2% of the order price to the customer.

In the event that the payment is not delivered to the supplier on time, the customer pays a penalty of 0.05% for each day of nonpayment. 

All arguments between the two parties are decided by the Government Arbitrage in Moscow."

CAMD RF 81-12038-33

SG-122

In late 1942, SU-122s and SU-76es entered production. However, as it often happens, not enough vehicles were produced to meet the army's needs. The need for a 76 mm SPG was solved with the SU-76I. In case of a medium SPG armed with a 122 mm howitzer, the military was luckier. Work on a StuG III with a 122 mm howitzer began earlier that year.

"To the chief of the repairs directorate of ABTU KA, brigade engineer Sosenkov
Copy to factory #592 director Pankratov

In accordance with the decision of the Deputy People's Commissar of Defense Lieutenant-General of the Tank Forces comrade Fedorenko on the re-armament of captured StuGs with model 1938 122 mm howitzers at factory #592, I ask you to arrange for four repaired StuGs to be delivered to factory #592. In order for work to proceed without delay, the first StuG should be received by April 25th.

April 13th, 1942
Chairman of the technical council, E. Satel"

The vehicle was indexed Self-Propelled Howitzer SG-122 (StuG) (Samohodnaya Gaubitsa SG-122 (Artshturm)), more commonly called just SG-122 and sometimes SU-122/T-3. The crew consisted of a driver, a commander, two loaders, and a gunner. As with many pre-war Soviet indirect fire guns, the M-30 had vertical and horizontal traverse controls on opposite sides of the gun, forcing the commander to aim horizontally, and the gunner to aim vertically. One of the loaders also performed the job of a radio operator.

The vehicle was armed with a 122 mm model 1938 howitzer (M-30). Much like the SU-76I, the SG-122 was protected with up to 45 mm of armour. The majority of the vehicle's insides remained the same. The radio was moved from the left side to the right, into a special addition to the vehicle's hull. External gas tanks were added to increase the vehicle's operational range.

SG-122(A), first prototype.

SG-122(A), first prototype, cutaway, showing maximum gun elevation.

SG-122(A), first prototype, top view, cutaway.

After trials in September, the following deficiencies in the design were discovered:

1. Insufficient off-road performance on soft terrain, and high pressure on front road wheels.
2. High pressure on the commander, due to also performing the duties of a gunner.
3. Insufficient operational range.
4. Difficulty in using gun ports due the position of the ammo rack.
5. Insufficient robustness of casemate armour plates.
6. Rapid buildup of gases in the fighting compartment. 

Two new prototypes were built on the PzIII chassis to resolve these issues. The vehicle was lightened by using 35 mm armour plates instead of 45 mm, and was equipped with wider winter tracks. The commander and gunner switched places, with the commander now performing horizontal aiming. Front hatches were removed to increase protection. The commander was also given an improver periscope and panoramic sight. The gun ports were replaced with those of superior design from the SU-76I. Their size allowed not only the use of the Nagant revolver, but any small arms used by the Red Army. The rate of fire was increased (according to Svirin, to a very rapid 7-8 RPM) by adding a loading tray. Large and awkward gun shields were replaced with an improved mantlet, more capable of protecting the weapon from bullets and shrapnel. An exhaust fan directly above the gun helped vent gases after firing.  

SG-122, improved prototype, front view, cutaway.

They were tested at the Gorohovets proving grounds shortly after the SU-122 decree, on December 5th. The SU-35 (SU-122) participated in these trials as well. Based on trial results, orders for the SG-122 were cancelled. Only 21 of these vehicles were produced. It is unknown how many used PzIII hulls and how many used StuG hulls, but M. Svirin writes that 8 StuG hulls were used for conversion into SU-76Is and SG-122s.

Actual combat use was complicated by a lack of spare parts and the use of a captured radio, which operated on a different range of frequencies than Soviet ones. In February of 1943, all existing vehicles were transferred to training units.

One experimental vehicle was produced using the PzIV chassis, indexed SU-122/T-4.

Information and images retrieved from Battlefield.ru, Solyankin et al, Domestic Armoured Vehicles of the 20th Century, Volume 2, Exprint, 2005 and M. Svirin, SturmGeshuetz III Assault Gun, Zeughaus, 2007

Re-arming German Tanks

The image of disciplined German soldiers methodically destroying their tanks so that the enemy does not get them is spread through popular history, but, in reality, was not true. The Red Army captured plenty of fully functional tanks, some in the first battle they ever participated in. They captured so many, that the issue of re-arming them came up. Re-arming German tanks with domestic guns would solve the problem with ammunition supply, if not the problems of parts and high-octane gasoline.

The question was first raised in 1942.

CAMD RF 81-12038-23

"According to the information supplied to you by deputy chief of the 2nd department of the Artillery Committee of GAU RA, engineer 2nd class comrade Getman on the necessity of re-arming captured tanks and SPG, and the discussion with engineers Sinilshikov and Pererushev, we decided that the following installations were possible:

1. 76 mm F-34 tank gun on the PzIV tank.
2. 45 mm tank gun on the PzIII tank.
3. 45 mm tank gun or 20 mm ShVAK autocannon on the Pz38(t) tank.
4. 122 mm howitzer M-30 on the StuG SPG.

Currently, Sinilshikov is only dealing with re-arming the StuG. His team already started developing a project. I am sending you a copy of the M-30 schematic, and if you do not object, please pass it on to comrade Sinilshikov. I am also sending you sketches of other turrets with German guns installed, to be used as you deem necessary. Keep me informed on your progress."

The M-30 project is the only one of these that went anywhere, creating the SG-122 (Self Propelled Howitzer, 122mm). 21 SG-122s were built out of StuGs and PzIIIs, but by that time the SU-122 was no longer used, and the equivalent SG-122s were sent to tank schools. Additionally, a project to install a 76 mm tank gun on the StuG was launched, creating the SU-76I, in 1943. 201 were built. 

A project to re-arm Tigers and Panthers was also launched. The Panther would receive an 85 mm gun and the Tiger a 100 mm gun. 

Here is a blueprint of a Tiger turret with a D-10T and a TsH-17 sight.

CAMD RF 81-12038-775

By 1945, the obsolete tanks were dropped and estimates on the work necessary were made.

CAMD RF 81-12038-775

A PzIV took 80 man-hours to convert to a ZiS-5 or a F-34. A Panther getting an 85 mm gun took 120 hours. A Tiger getting the D-10T took 90 hours. A fragment of the blueprint shows the true name of this chimera: T-VI-100.

However, by 1945, victory was near and the tank shortages of 1941/42 were long behind. Captured tanks were no longer needed by anyone except museums, and work on re-arming them stopped.