Ammunition Storage

 "#01725
June 9th, 1945

In accordance with your letter #843079s dated May 25th of this year, we present the following ideas regarding rational locations of ammunition in ammunition racks and painting of the racks with the goal of prevention of explosions.

For the SU-76

1. Given 35 round of HE, 15 AP, and 10 APCR, place:
1. 11 rounds of HE on the right side, 17 on the left side, 7 under the gun cradle.
2. 15 rounds of AP in the upper bustle.
3. 10 rounds of APCR in the lower bustle.

Far East Reliability

 "September 29th, 1945

The following technical defects were discovered in tanks and SPGs of the Transbaikal Front after crossing the Manchurian and Mongolian steppe, mountains of the Greater Khingan, and the heavily swamped region until Changchung and Mukden.

1. Widespread cases of melting battery seals on T-34 tanks and SU-100 SPGs.
   Due to the low quality of seals (low melting temperature) and lack of asbestos packing cords, the seals melted, seeped into battery cells, and covered the upper parts of the plates. Refurbishment of batteries was successfully carried out by brigade and regiment level repair units.
2. Widespread cases of destruction of M4A2 road wheel tires.
   Destruction happened chiefly due to poor vulcanization of the rubber and especially difficult road conditions (high ambient temperature and sand-stone terrain).

100 Stings

Even though mass production of SU-100 tank destroyers began in September of 1944, their debut in battle was delayed until January of 1945. Front line troops would no doubt have been glad to have a new methods of hunting German "beasts", but this way crews would go into battle having mastered their vehicles and built cohesion within regiments and brigades. It was three SPG brigades, the 207th, 208th, and 209th, that made up the main users of the SU-100 during the battles at Lake Balaton that began in March of 1945. These crews could now present a well balanced opinion on their vehicles.

Brand new SU-100s lined up at the Uralmash factory.

An Alternative Layout

SPG designs hit a dead end in many nations by the end of WWII. The concept of a heavier gun on the same chassis stopped working. Regular guns were getting so large that there were issues with the chassis. The results were essentially the same as just putting the gun in a tank with a rotating turret. This was especially true for medium SPGs. Germany, the USSR, and Great Britain eventually ended up with medium tanks that had the same gun as medium SPGs. Several nations (especially Germany and the USSR) ended up overloading the front suspension. This led to a search for new solutions. This led to the Uralmash-1, the most unusual Soviet late war SPG.

Video: SPG or Tank Destroyer?

In this week's video, I take a look at a commonly asked question: what's the difference between a self propelled gun and a tank destroyer? Was the SU-152 either or both? Watch and find out!

Lesson Plan

"March 20th, 1945

Syllabus for technical preparation of crews for usage of tanks and SPGs in spring-summer conditions

Objective: to teach the main rules of  moving over to using tanks and SPGs in the spring and summer and learn the specifics of using tanks and SPGs in the spring and summer.

Time allotted: 12 hours, one hour per day

Location: in classrooms and in vehicles

Training conducted by: technical deputy commanders of companies and battalions

Optimal Modernization

GKO decree #3892ss "On organization of 85 mm SPGs on the T-34 chassis at the Uralmash factory" was signed on August 8th, 1943. The first 100 vehicles of this type were ready by early September. The SU-85 ended up being the most numerous Soviet SPG of the war. However, the question of its successor was already raised at the start of its production. The cause of this was information from the Kursk salient about new German Panther tanks and Ferdinand SPGs. A program to develop a gun more powerful than the D-5 was launched in September of 1943. The result was the SU-100, the best Soviet medium SPG of the war.

Lessons Learned

"Secret

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.

SU-100, Czechoslovakian Style

Domestic tank and SPG designs took a downturn in post-war Czechoslovakia. The cause of this was more technical than political. Czechoslovakian engineers could not keep up with the changing requirements of the Czechoslovakian military. As a result, Czechoslovakia began licensed production of T-34-85 tanks in September of 1951. A similar situation took place with medium SPGs. Just under 800 SD-100 SPGs, licensed clones of the SU-100, were built.

A Different Angle

There is a strangely prevalent opinion in some circles that everything there was to know about WWII was already known, and that any new information is completely unnecessary revisionism. Those people are naturally wrong, as illustrated pretty conclusively by Yuri Pasholok. Something as fundamental as a measurement went uncorrected for decades.

SU-100 Review

"March 12th, 1945

Comments on the use of the SU-100 SPG in combat

1. During the fighting of the Corps from January 14th to March 10th, 1945, SU-100 SPGs were used as tanks, as the Corps fought in operative depth and was almost entirely equipped with SU-100 SPGs.
2. The off-road mobility of the SU-100 is reduced compared to the T-34 tank, due to the increase in weight and shifting of the center of mass forward due to the longer gun and thickening of the front armour. This adds additional load on the front wheels.
   When crossing obstacles off-road, the gun can strike the ground and then the barrel bursts when firing. The gun mount can shift during sudden turns and driving on uneven terrain. There were cases of a complete breakaway of the elevation mechanism.

D-10 in the IS-2

"To the Commander of the Motorized and Mechanized Forces of the Red Army, Marshal of the Armoured Forces, comrade Ya.N. Fedorenko

Having examined the results of comparative trials of the 122 mm D-25 gun and 100 mm D-10 gun, the Red Army GAU concludes that:

1. The rate of fire of the D-10 gun is up to three times higher than that of the D-25 gun, which is a significant advantage of the D-10 gun.
   The 100 mm D-10 gun presently has an insufficiently robust armour piercing shell, which does not guarantee reliable penetration of the Panther's armour at a range of over 1200 meters.
   The decision to install the 100 mm D-10 gun on the IS tank should be delayed until the armour piercing shell and semi-automatic mechanism of the D-10 gun are perfected.
   Since the 100 mm D-10 gun and its ammunition in its existing form are already significantly more powerful than the 85 mm D-5 gun, it is necessary to rearm the SU-85 SPG with the 100 mm D-10 gun, for which a pilot batch of SPGs with the D-10 gun should be produced with corrections of drawbacks of the gun and SPG that were revealed during trials.
2. The 122 mm D-25 gun reliably penetrates the front armour of the Panther tank from a range of over 2000 meters.
   The armour piercing shell of this gun is sufficiently robust, and the HE grenade has a sufficient explosion and fragmentation effect.
   Until the ammunition and components of the D-10 gun are perfected, the 122 mm D-25 gun must remain as the main armament of the IS tank.

Conducting experiments with the creation of a 122 mm single piece round is reasonable, but you must consider that the use of a single piece round will require a change to the chamber, sunk part of the shell, and the casing.

The mass and dimensions of a unified 122 mm round will make the loader's job more difficult, which will definitely not increase the rate of fire of the D-25 to the level of the D-10.

Regardless of the result of comparative trials of the D-10 and D-25 guns, the installation of the S-34 gun in a tank and an SPG will continue. 

Commander of Artillery of the Red Army, Chief Marshal of Artillery, Voronov
Marshal of Artillery, Yakovlev
April 20th, 1944"

CAMD RF 38-11369-490 pp. 35-38

Lethality in Berlin

Some interesting data from the 2nd Guards Tank Army gathered during their fighting in Berlin. Analysis of tanks that were badly damaged enough to have to be written off from their unit was performed at the repair base. There, a decision was made: either the tank is irreparable and is destined for the scrap heap or is salvageable, but only after refurbishment, and is thus sent to the factory. Unfortunately there are no notes that tell us why each specific type of tank typically became unsalvageable, but only a general rule of thumb: if the ammunition rack is hit, the tank blows up and is a complete loss. If the ammunition does not go off, then the tank will probably be suitable for refurbishment, even if there was a fire.

Type	Total	T-34		IS-2		M4A2		SU-76		SU-85		SU-100		ISU-122
		Irrep.	Maj.	Irrep.	Maj.	Irrep.	Maj.	Irrep.	Maj.	Irrep.	Maj.	Irrep.	Maj.	Irrep.	Maj.
75 mm shell	39	6	8	-	-	3	16	2	2	-	2	-	-	-	-
88 mm shell	27	7	3	7	-	4	4	-	-	-	-	1	-	1	1
100 mm shell	9	2	2	3	-	1	1	-	-	-	-	-	-	-	-
22 mm AA gun	5	-	1	-	-	4	-	-	-	-	-	-	-	-	-
Artillery total	80	15	14	10	-	12	21	2	2	-	2	1	-	1	-
Faust	47	16	2	2	1	13	8	3	-	-	-	1	-	1	-
Aircraft	4	-	-	-	-	-	2	-	-	-	-	-	-	2	-
Mines	4	2	-	-	-	-	-	-	1	-	-	1	-	-	-
Total	135	33	16	12	1	25	31	5	3	-	2	3	-	4	-