Tanks and trucks

SP-Guns Specifications

2009-11-05T21:06:16Z

AFV designation	AFV name	Weight, kg	Crew	Dimensions, m	Clearance, m	Armament	Ammunition	Speed		Obstacles					Ground pressure, kg/cm²	Max. range, km	Engine				Radio	Internal communic.
AFV designation	AFV name	Weight, kg	Crew	Dimensions, m	Clearance, m	Armament	Ammunition	On road, km/h	Off road¹, km/h	gradient, degr.	side gradient, degr.	trench, m	vertical wall, m	fording, m	Ground pressure, kg/cm²	Max. range, km	index	type	cylinders	power, hp	Radio	Internal communic.
ZIS-30	light tank destroyer	?	5	?	?	57 mm ZIS-2 gun, 1 x 7.62 mm DT BMG	57 mm: 20, 7.62 mm: 756	47	?	?	?	?	?	?	?	150	GAZ M-1	petrol	4	50	?	?
SU-76M (SU-15)	light self-propelled gun	10 600	4	4.97x2.72x2.1	0.3	76.2 mm ZIS-3Sh gun	60	45	19	28°	30°	1.6	0.6	0.9	0.545	190	2 x GAZ-203	petrol	6	2 x 70	9R	TPU-3
SU-122	medium assault gun	30 900	5	6.95x3x2.24	0.4	121.9 mm M-30 howitzer	40	55	25	35°	25°	2.5	0.73	1.3	0.73	150	V-2-34	diesel	12	500	9R	TPU-3-BisF
SU-85	medium tank destroyer	29 600	4	8.13x3x2.3	0.4	85 mm D-5S gun	48	55	25	35°	25°	2.5	0.73	1.3	0.7	150	V-2-34	diesel	12	500	9R or 9RS	TPU-3-BisF
SU-85M	medium tank destroyer	31 200	4	8.13x3x2.25	0.4	85 mm D-5S gun	60	50	20	35°	25°	2.5	0.73	1.3	0.8	140	V-2-34M	diesel	12	520	9R or 9RS	TPU-3-BisF
SU-100	medium tank destroyer	31 200	4	8.13x3x2.25	0.4	100 mm D-10S gun	34	50	20	35°	25°	2.5	0.73	1.3	0.8	140	V-2-34M	diesel	12	520	9R or 9RS	TPU-3-BisF
SU-152	heavy assault gun	45 500	5	8.95x3.25x2.45	0.44	152.4 mm ML-20S howitzer	20	43	14	36°	30°	2.5	1.2	1.6	0.85	165	V-2K	diesel	12	600	10R or 10RK	TPU-3R
ISU-152	heavy assault gun	46 000	5	9.05x3.07x2.48	0.47	152.4 mm ML-20S howitzer, 1 x 12.7 mm DShK AAMG	152.4 mm: 20, 12.7 mm: 250	35	18	36°	30°	2.5	1	1.3	0.8	145	V-2-IS	diesel	12	520	10R	TPU-4-BisF
ISU-122	heavy assault gun	46 000	5	9.85x3.07x2.48	0.47	121.9 mm D-25S gun, 1 x 12.7 mm DShK AAMG	121.9 mm: 30, 12.7 mm: 250	35	18	36°	30°	2.5	1	1.3	0.8	145	V-2-IS	diesel	12	520	10R	TPU-4-BisF
ISU-122S	heavy assault gun	46 000	5	9.85x3.07x2.48	0.47	121.9 mm D-25S gun, 1 x 12.7 mm DShK AAMG	121.9 mm: 30, 12.7 mm: 250	35	18	36°	30°	2.5	1	1.3	0.8	145	V-2-IS	diesel	12	520	10R	TPU-4-BisF

ABBREVIATIONS:
TMG - turret machine-gun;
CMG - coaxial machine-gun;
BMG - bow machine-gun;
RMG - rear machine-gun;
AAMG - antiaircraft machine-gun;
GAZ - Gorkovskiy Automobil Factory;

ZIS-30 Light Tank Destroyer

2005-09-20T19:04:56Z

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At the beginning of the Great Patriotic War Red Army had neither tank destroyer nor SPAA in mass production. Before the war, several projects were developed; some of them were built. However all of that projects were abandoned later for various reasons. That's why, in July 1 of 1941, the Minister of Weapons signed an order to develop and produce a 37mm SPAA, an 85 mm SPAA and a 57mm TD. All projects were to be finished not later July 15, 1941. The development of a 57 mm TD was assigned to the Factory #92 in Gorky (today - Nizhnij Novgorod).

To accomplish this task a special group of engineers was summoned to the factory's design bureau. The head designer was P.F.Murav'ev. In a very short time the new SP was designed and realized as a prototype.

It should be noted that two different prototypes were built: the ZIS-30 and ZIS-31. The ZIS-30 was a light tank destroyer based on the "Komsomolets" tractor. It was armed with an open 57 mm ZIS-2 AT-Gun, protected only by the gun's shield. For better stability the TD was equipped with two extendable skids (you can see them at the rear of the vehicle in the photo below).

The ZIS-31 had the same armament but was based on an armored truck GAZ-AAA. In July-August both TD's were tested. The tests showed better gunnery results for the ZIS-31. However the ZIS-30 showed better maneuverability in rough and swampy terrain, and was thus selected for service.

The Factory #92 was ordered to begin ZIS-30 production by September 1, 1941. However, a new problem appeared: at that time the only one factory produced the "Komsomolets" tractors - it was Moscow factory #37. However, in August 1941 this factory switched its production from tractors to tanks, so no factory in the USSR produced this type of tractor any more. Then the decision was made to collect tractors from Red Army's units. You can imagine the condition in which those tractors were received after their use in the Army! As a result the production of the ZIS-30 tank destroyer began on September 21 and continued up to October 15, 1941. During this period the factory #92 produced 101 TDs (including one experimental TD) with the 57 mm gun and one TD with a 45 mm AT-gun. Further production was cancelled because of a lack of tractors.

The ZIS-30 tank destroyer served from the end of September 1941. Some of anti-tank batteries and 20 tank brigades of the Southwestern and Western Fronts were equipped with these TDs. Notice at that time this TD was called the "ZIS-2 57 mm AT-Gun".

The new tank destroyer was very successfull because of its excellent gun (in 1941-1942 this TD could penetrate any type of German tank from long distance). However, this TD still had several disadvantages:
- poor stability during firing (vehicle is jumping);
- overloaded chassis;
- low fuel capacity;
- low ammunition capacity;
- unprotected crew;
- lack of radio.

By the summer of 1942 most of these TD's were lost. Some were destroyed during battles, other were lost because of technical failures.

Sources: "World War II", Quadrillion Publishing Ltd.
"M-Hobby" #4 1997
"Bronekollektsiya" #1 1998

SU-85 Tank Destroyer

2005-09-20T16:39:47Z

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When the first German Tiger was captured at Leningrad in January 1943, the Soviet High Command was shocked. Its armor was too thick for most Soviet guns. The most common Soviet tank gun, the F-34 Tank Gun (installed in the T-34) and the ZIS-5 Tank Gun (installed in the KV-1) could penetrate it only from suicidally short distances.

Special ballistic tests showed that the M-30 howitzer (mounted on a SU-122 Assault Gun) wasn't effective against the Tiger. Using the HEAT ammunition M-30 was able to penetrate the Tiger's armor, but slow rate of fire and curved trajectory (don't forget that M-30 was a howitzer, not a field gun) made SU-122 quite an easy target.

A special tests revealed that the two most effective guns against the Tiger's armor were the 85 mm AA-gun and the 122 mm A-19 corps cannon. So, Petrov's design bureau was ordered to develop a new tank destroyer - an 85 mm gun that would be mounted on an SU-122 chassis which had been designed by L.Gorlitsky.

That is why, by the GKO order from May 5, 1943, a F.F.Petrov's design bureau has started works on adapting the 85 mm AA gun model 1939 for further rearm with it SU-122. Simultaneously, the TsAKB (a design bureau lead by V.Grabin) has started their works on rearming SU-122 with already existed 85 mm S-18 gun. Initially, that has been developed for KV heavy tanks. A slightly improved, with new gun mantlet and new gun-cradle, S-18 was delivered to the Uralmash.

However the attempt to install it in the standard compartment of SU-122 was failed because of too big breech end of the gun. Uralmash tried to reject all further works cause it led to modernisation of a whole hull, thus it led to a big expenses. However it was forced to continue works. As a result, two different vehicles have been built.

The first one - the SU-85-I - had a standard hull of the SU-122, but had the new gun-cradle and the new gun mantlet. The initially proposed coaxial machine-gun was later removed because of lack of room.

The second one - the SU-85-IV - was based on the SU-122 as well, but had a modified front. Both self-propelled guns were armed with the 85 mm Tank Gun S-18.

As I said above, simultaneously the works on S-18, works on installing the Petrov's 85 mm D-5S gun into to SU-122 have been conducted. Initially D-5S was considered as a temporal step until the problems with S-18 will be solved. However, on a comparative trials, D-5S showed the same ballistic but better performance and reliability. Nevertheless the successfully passed trials, the existed gun-cradle didn't allow to add a telescopic sight. Thus, a new sight TSh-15 has been developed. The new self-propelled gun was named SU-85-II.

Comparative trials proved the superiority of the SU-85-II over the SU-85-I. The SU-85-IV was removed from trials earlier because of some serious defects. SU-85-II was accepted for service as a "self-propelled antitank gun SU-85".

The SU-85 had 48 rounds for its gun, in addition it had 1500 rounds for the crew's sub-machine guns, 24 grenades F-1 ("pineapple") and 5 antitank grenades. The transmission, engine and most of other components were left unchanged (the same as in the T-34-76), allowing easy transition for new crews.

The first batch of SU-85 tank destroyers were equipped with an armored commander's cap. Later it was replaced by the standard commander's cupola - the same as on the T-34-76 model 1942. Besides, crew could use a prismatic observation sights installed in left side and rear. On later vehicles the some additional optic was installed which made an almost all-round observation.

In the front and the sides there were embrasures for firing with small firearms. These embrasures might be closed with a conic spigots. Basically, SU-85 was similar to SU-122 excluding its armament.

In September 1943, during the Dnieper crossing, there was the very first usage of SU-85's. This TD become a very popular in the Red Army due to its powerful gun that was able to penetrate German Tigers and Panthers from a quite long distances. For example, in 1944, during the summer offensive, the 1021st Self-Propelled Artillery Regiment (1st Baltic Front) destroyed over 100 German tanks. Another example, taken from a commander's report of the 1st Guards Tank Army:

"During all phases of the battle, the new tank destroyers played a key role in supporting our armored attack. New TD's were very effective against enemy tanks. They had of good armor protection and their guns could kill targets at great distances. In addition, new TD's proved to be very effective in defensive."

With the advent of the deadlier SU-100 Tank Destroyer, the production of SU-85's was canceled. Sum totally, 2329 SU-85's and 315 SU-85M's were built.

The SU-85 saw service beyond the Red Army: 70 SU-85's served in the Polish Army (Voisko Polskoye) and 2 vehicles served in the Czech Corps.

Because of problems with with 100 mm AP ammunition, the mass production of the SU-100 was delayed. At the same time, the SU-85 was already removed from production (from July 1944).

Thus, a temporal step was made: a SU-100 tank destroyer armed with an 85 mm D-5S was developed and set up in the mass production. That "temporal" variant received SU-85M designation. It distinguished from common SU-85 by thicker frontal armor (75 mm instead of 45 mm) and by spacious compartment. It produced until December 1944, when the production of SU-100 was launched.

Besides of the production SU-85s and theSU-85Ms, there were several experimental vehicles which didn't accept by various reasons.

In autumn 1943 after the long and detailed investigating of the German heavy Ferdinand tank destroyers GAU ordered some design bureaus to develop a new more powerful antitank gun which would be able to fight with German heavy tanks and TDs. As an example it was suggested to use German 8.8cm PaK 43.

One of the first project was offered by F.F.Petrov's design bureau. A redesigned D-5 gun - which was designated D-5S-85BM - had longer barrel. Using a standard 85 mm rounds and increased powder propellant charge, the muzzle brake of AP round was increased up to 950 m/s. At the same time, new gun allowed to use a standard ammunition as well. Gun was installed in the hull of the standard SU-85. New TD was named SU-85BM ("BM" means "bol'shaya mosh'nost" - big power). From January to March 1944 it was tested on a proving ground. By its results, SU-85BM was not accepted for service.

Notwithstanding the previous attempt, in autumn 1944 Petrov's design bureau offered another variant of 85 mm gun: a 100 mm B-34 Naval Anti-aircraft Gun which was re-bored to the 85 mm caliber. New gun was named D-10-85PM and tank destroyer - SU-D-10-85. It used a standard 85 mm rounds and 100 mm cartridges borrowed from a 85mm AA gun Model 1939. In summer 1944, this new TD was tested but didn't accept for service.

Besides of Petrov's design bureau, the Grabin's design bureau was involved. In spring 1944, it developed a new tank destroyer SU-S-34-1 armed with 85 mm S-34-IB gun. It had an unusual ammunition: a 85 mm round with a 100 mm cartridge. In summer 1944, the new TD was tested but didn't accept for service.

SU-76i Assault Gun

2005-09-20T16:38:49Z

The first attempts to re-arm captured self-propelled guns with domestic weapons were conducted in Moscow factories in the fall of 1941 to the beginning of 1942. According to A. Klubnev's memoirs, in March 1942, when he was the commander of a platoon of T-60 tanks (33rd Army), six repaired StuG III's arrived. Three of them were armed with the original StuK gun, while "the three other vehicles were armed with early production T-34 guns" (probably the 76.2 mm Tank Gun L-11). P. Minkov also fought in the 33rd Army, and he described the same vehicle that "was armed with the gun of the KV tank." He mentioned this vehicle was knocked out at Medyn' in the spring of 1942.

Unfortunately, I was unable to find any documented proof of such vehicles (neither photos nor documents). I suppose it was an isolated instance, and they were not production vehicles.

In January and February 1943, most newly-accepted SU-76's (SU-12's) had to be repaired because of many mechanical failures, and therefore the Red Army was deprived of important vehicles. The situation had to be improved immediately, before the beginning of the 1943 Summer Offensive. I. Kashtanov proposed to rearm the SG-122 with the divisional 76.2 mm gun (the original SG-122A was based on the chassis of the captured German Pz-III and armed with the 122 mm Howitzer M-30). This was a good proposal since the USSR possessed more than 300 ex-German tanks, which were captured after the Battle at Stalingrad. Kashtanov's project was accepted on February 3, 1943, and there was little time to finish the project, as it had to be accomplished prior to March 1, 1943.

Kashtanov and some other engineers moved to Factory #37 in Sverdlovsk, where they continued their work to re-arm the SG-122. Initially, they planned to mount the 76.2 mm cannon ZiS-3Sh on a pedestal fitted on the floor. Unfortunately, this plan did not provide reliable protection from bullets and shell fragments.

The problem was solved by using the 76.2 mm Tank Gun S-1. This weapon was designed specially for self-propelled guns, it was based on the F-34 Tank Gun, and was very cheap. The S-1 was distinguished from the original F-34 by a framework that allowed it to be easily mount directly on the frontal armor plate (i.e. without an additional pedestal).

On February 15, 1943, S. Ginzburg reported to the minister of the NKTP that "... Factory #37 started manufacture of the experimental 76 mm self-propelled gun S-1." On March 6, the SP-gun was finished and sent to factory trials.

These trials were conducted in the Sverdlovsk area, and consisted of racing on snow (off-road) and on ice-covered roads. Despite cold temperatures (-35° C) the vehicle successfully passed all trials and on March 20, 1943, it was recommended for service under the SU S-1 designation. (I have also seen the designations: SU-76 (S-1) and SU-76i where the "i" suffix means "inostrannaya" - foreign).

On April 3, 1943, the first five production SU-76i had been sent to the Training Self-Propelled Regiment, that was located in Sverdlovsk area. In one month of intensive operation, these vehicles ran 600 to 700 kilometres and helped to train over 100 new tankers. All the tankers liked the new SP-guns but mentioned problems starting the engine while frozen: to start a frozen engine, they poured burning petrol in it (this is not a joke!)

At that time, the factory launched production of the new 20 SU-76i, which were sent to the training units. From May 1943, the SU-76i appeared on the front lines.

The first vehicles looked very spartan. Their battle compartment was of welded 35-mm armored plates on the front, 25-mm plates on the sides, and 15-mm on the rear. Initially, the roof was made of a single armored plate and fitted with bolts. Despite what some modern tank "experts" state, the absence of a roof is not an obvious disadvantage of any AFV - many Soviet crews removed the vehicle's roof to make the vehicle more habitable.

In the beginning 1943, because of a shortage of radios, a radio was installed on every third vehicle. From May 1943, almost every SU-76i was equipped with the 9-R radio.

In July-August 1943, after the experience gained from the Battle of Kursk, an additional armored shield was fitted on the gun. This shield was intended to protect the gun from jamming from shell fragments and bullets. Simultaneously, the SU-76i began to be equipped with two external fuel tanks.

The first SU-76i's were equipped with the original German commander's cupolas taken from captured PzKpfw-III's. In August 1943, a decision to produce some commander version of the SU-76i's was accepted. Each commander SU-76i was equipped with a commander's cupola and a radio of extra range. Such vehicles had reduced ammunition load.

The last SU-76i left the factory gates in November 1943. By that time, the problems with domestic SU-76 were fixed and they put into mass production, and the SU-76i was no longer needed. The Soviet SU-76 was much cheaper to manufacture, easier to maintain, and much easier to supply with spare parts. In total, Factory #37 manufactured 181 SU-76i plus 20 commander SU-76i.

SU-76i's first saw Battle at Kursk. In the beginning of July 1943, the 13th Army of the Central Front possessed sixteen SU-76i. During the defensive stage of the battle, eight vehicles were lost, three of which were burnt-out. The Voronezh Front also had some SU-76i, but unfortunately they only reported the total number of all 76-mm self-propelled guns - 33 vehicles.

It is also known that during the advance on Orel, the Central Front was reinforced with two SAP. One of these regiments had 16 SU-76i and one PzKpfw III.

On August 2, 1943, the 5th Guards Army was reinforced with the 1902nd SAP, which had 15 SU-76i. Before August 14, the regiment didn't fight, but was repairing its SU's and awaited trucks (initially there were only 10% of the needed trucks in the regiment). At that time, the regiment also received five SU-122's. From August 14 to 31, the regiment was engaged in five battles. The regiment destroyed two tanks, nine cannons, twelve machine-guns and over 250 men. According to the 1902nd Regiment Commander's report:

"...every vehicle has some damage. Some vehicles were recovered several times, all vehicles based on PzKpfw-III are depreciated and now in very poor condition. The regiment was constantly under-equipped, but the experience for the personnel was quite good."

In September 1943, the regiment participated in fourteen battles, in every battle, the regiment used from two to seven self-propelled guns simultaneously. The most effective battles occurred from 20 to 23 September of 1943, when six SU-76i's pursued the Germans and destroyed three tanks. Usually, during pursuit or attack, self-propelled guns followed the Soviet tanks. The commander stated "...if tanks and SP-guns could be used on a more massive scale, losses could be reduced significantly." The regiment fought until November. On November 25, 1943, the 1902nd SAP was sent as reinforcements since it lost all its vehicles.

In addition to the 1902d SAP, SU-76i's were in the 1901st and 1903rd SAPs, which also fought in August and September during the Belgorod-Khar'kov offensive operations.

Finally, during the Kursk Battle, some Soviet self-propelled artillery regiments used captured German self-propelled guns. For example, on August 10, the 1938th SAP of the 7th Guards Army had two SU-122, two SU-76 (SU-12), and two SU-75 (StuG III).

Soviet tankers liked the SU-76i because it wasn't as cramped as the SU-85, SU-122, or the captured StuG 40. Only one serious disadvantage was mentioned: the vehicle had only one hatch (by 1943, German tanks with side hatches almost completely disappeared), so there was a problem with escaping the vehicle if it was burning.

Quite interesting evidence about the SU-76i was found in German reconnaissance reports. On October 25, 1943, the Staff of the German 1st Panzer Army written a report to the directorate "Foreign armies - East":

"In the 177th Panzer Regiment of the 64th Mechanized Brigade there are four companies of eleven tanks in each. These tanks are named "Sturmgeschutz 76 mm." They are based on the chassis of the German Panzer III with the Maybach engine. The new battle compartment has 3-4 cm armor thickness on the front; 1-1.5 cm on the sides. The battle compartment is opened from the top. The gun has horizontal angle +15° and vertical angle ±7°."

This report is quite confusing. At first, the report is obviously describing the SU-76i. On the other hand, self-propelled guns could not be assigned to a tank regiment of the mechanized brigade. Most probably, the report is about the SAP - self-propelled artillery regiment, but in this case, the total number of the SP-guns is doubled anyway, since each SAP had 22 vehicles.

From August 1943, Kashtanov's design bureau attempted to rearm the SU-76i. On September 14, 1943, the Chief Engineer of Factory #37 received a letter from Frezerov (Chief of the Tech Department of the NKTP):

"Your new project to mount the 85 mm gun D-5-S-85 onto the chassis of the PzKpfw III (the SU-85i) cannot be realized because of a shortage of 85-mm guns and an unclear situation with Pz-III tanks.

I think this project must be cancelled, but all documents must be saved for later possible usage."

This project ended all attempts to use chassis of captured tanks for Soviet tanks and SP-guns. In the beginning of 1944, Fedorenko (Chief of the GABTU) issued an order to transfer all existing SU-76i from combat units to training units.

In training units these vehicles were used until the end of 1945, and after that they were written off. In Kubinka, one working SU-76i was used for a very long time and was written off in 1968. Today, only two SU-76i remain. The first one was accidentally found and recovered from Sluch River and now it is displayed as a monument in Sarny (Ukraine). The second one was discovered by "Ekipazh" Searching Group and now it is displayed in museum on Poklonnaya Hill in Moscow.

Sources: "Trophies in the Red Army", Frontovaya Illustratsiya #1, 2000;
M.Kolomiets, M.Svirin "Kurskaya Duga", ExPrint NV, 1998;
"Poligon" #1, 2000.

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Light Self-Propelled Guns of the SU-76 Series

2005-09-20T16:37:40Z

{tab=Development history}

Development History

When the Red Army entered the Second World War the Soviet Union did not have any mass-produced self-propelled guns that could be used both for close support of the infantry and for an anti-tank role. In the late 1930's a very limited number of SU-5 self-propelled guns was built based on the chassis of the T-26 Light Tank, but they only had limited use during the occupation of Poland in 1939.

By summer 1941 this lack of a suitable self-propelled gun appeared so serious that in September a ZIS-30 self-propelled gun was developed as a temporary measure. Being based on the chassis of the "Komsomolets" armored tracktor this vehiclehad limited fuel capacity, also it was overweighted, and had poor stability during gunfire/ On the other hand it could defeat anything Panzerwaffe disposed and that ewas the most importand at that time. In this way the Red Army was provided with inexpensive self-propelled antitank weapon.

In the 1930's, there were some successful attempts at developing self-propelled assault and anti-aircraft guns on the chassis of the mass-produced T-26 light tank, which led to the manufacture of several experimental vehicles.

{slide=SU-76P}

SU-76P

With the arrival of new tank models, the T-26s could theoretically be converted to self-propelled guns, but in reality, conversion was impossible due to great T-26 losses during the first months of the Great Patriotic War. It was also impossible to replace the T-26s with new tanks due to the fact that the tank factories were being evacuated to the Urals and to Siberia. However, in besieged Leningrad in 1941 to 1942, several small batches of SU-76P were manufactured. The SU-76P consisted of a 76 mm regimental field gun installed on a T-26 chassis with a circular field of fire, and it had no protection for the crew other than the gun's shield. But this vehicle was merely another stop-gap measure, as the besieged city had to make do with whatever equipment it had remaining inside the encirclement.

In autumn 1941, all tanks armed with 45 mm guns which fought on the Leningrad Front become useless against "soft" targets like infantry due to the lack of fragmentation and high-explosive ammunition. That's why the General Staff of the Leningrad Front asked the NKTP to rearm existing BT and T-26 light tanks with the 76 mm KT Gun.

A new vehicle was developed and tested, and after successful testing, the General Staff of the Leningrad Frond ordered Factory #174 to start manufacturing the new self-propelled guns. This vehicle received the SU-76 designation, and from 1943, it was renamed the SU-76P (P - "polkovaya" - "regimental") to avoid confusion with the new self-propelled gun which had the same designation (see below).

{/slide}

{slide=OSA-76 (OSU-76)}

OSA-76 (OSU-76)

The SU-76P alone could not solve the Red Army's lack of self-propelled guns, and there were attempts to utilise the chassis of T-60 tanks, which were mass-produced in 1941 to 1943. In autumn 1941 the GAZ Factory began on its own initiative the development of a light self-propelled gun designated the SU-71. However, it never entered full-scale production. By July 1942, another self-propelled gun was developed: the OSA-76, which was based on the chassis of the T-60 tank.

That project was developed by an initiative of GAU, which involved the idea of installing all field artillery on self-propelled chassis. An "OSA" designation means "Obshevoiskovaya Samokhodhaya Artilleriya" (All-Purpose Self-Propelled Artillery). In fact, OSA does not belong to the SU-76 series, as it was rather an independent class of self-propelled guns. The whole OSA project resulted in the development of the following partially-armored vehicles:
- OSA-76 - a partially armored vehicle with a 76 mm self-propelled gun;
- OSA-57 - a partially armored vehicle with a 57 mm self-propelled antitank gun;
- OSA-23 - a partially armored vehicle with a 23 mm self-propelled antiaircraft gun;
- OSA-12 - a partially armored vehicle with a 12.7 mm self-propelled antiaircraft gun.

The OSA-76 was armed with the 76.2 mm Assault Gun ZIS-3Sh based on the 76.2 mm Divisional Gun ZIS-3. The vehicle had a very low weight - less than 3,500 kg. The GAZ-MM gasoline engine powered it. The chassis of the OSA-76 was the same as on the T-60/T-70 light tanks. It had a crew of three men, and the armor protection was 6 mm. The OSA-76 successfully passed all tests and was recommended for mass production, although it was ultimately never produced.

An attempt by Rumanian engineers to install a captured 76.2 mm F-22 gun on the chassis of a captured T-60 tank was more successful. Until the arrival of the German Pzkw IV Ausf G, they were the only means to reliably defeat Soviet medium and heavy tanks.

{/slide}

{slide=SPG of Factory No.37}

Self-Propelled Gun of Factory No.37

This was a self-propelled gun of the SU-76 series. The development of this vehicle followed the NKAP order of March 3, 1942. By May 1942, the first experimental prototype was manufactured and sent to the proving grounds. However, neither the chassis nor the armament passed the trials. The construction of this vehicle was based on the chassis of T-60 light tank.

{/slide}

{slide=SU-12 (SU-76)}

SU-12 (SU-76)

On October 19, 1942, the GKO issued Document #2429ss ordered the GAZ Factory and Factory #38 to develop, to test, and to put into full-scale production a light SP gun, armed with the 76.2 mm Gun ZIS-3. The new vehicle was based on the chassis and engine of the T-70 tank, but with increased length, and an additional road wheel.

In November 1942, both factories showed their prototypes. Both vehicles were armed with the ZIS-3Sh ("Sh" means "shturmovaya" or "assault") gun. The GAZ project was named the GAZ-71, and Factory #38's project was named the SU-12. On December 9, 1942, after comparative trials, the GAZ-71 was recognized as "not conforming to existing battle requirements", and was "very unreliable"; and thus, further work was cancelled. The SU-12, however, was accepted for service under the name "SU-76 Self-Propelled Assault Gun." From January 1, 1943, mass production began.

The designers put the two GAZ-202 engines parallel to one another instead of in-line as on the T-70 tank. Its fully-enclosed shielding was welded from 10 to 35 mm armor plates, the driver's compartment was located in the front of the vehicle in between the engines, while the superstructure housing the ZIS-3Sh gun was located in the rear.

The crew of three also had a DT machine-gun and personal firearms at its disposal. By the end of January 1943, it formed the first two self-propelled artillery regiments sent to the Volkhov front.

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{slide=SU-76M (SU-12M)}

SU-76M (SU-12M)

The shortcoming of the parallel engine placement in the SU-76 (SU-12) became apparent when it resulted in transmission malfunctions. The malfunctions were due to torsional vibrations which led to rapid breakdowns. The vibration peaked in second gear, which was the most overloaded gear. It was impossible to properly synchronize the two engines.

As a result of the experiences in the field, the production of SU-76 was halted on March 21st, 1943, after only 350 were produced. Due to the planned summer offensive, the GKO put a very strict time-frame to correct the defects. Already by May 17th, 1943, an updated SU-76M (SU-12M; M means "modernised") entered testing and by June of that year it entered production.

These vehicles had updated engines and transmissions, and used the old SU-76 hulls that were left over. Improvements included the introduction of spring clutches between the engines and the main gear, of a slipping clutch on the general shaft, and of engine shock absorbers. These items reduced, but did not eliminate, the likelihood of a malfunction. In May 1943, the production of the SU-76M began. All of those vehicles took part in the Battle of Kursk.

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{slide=SU-15, SU-16, SU-38}

SU-15, SU-16, and SU-38

By summer 1943, the design bureaus of the GAZ factory and Factory #38 offered several independent projects on how to modernise the SU-76. GAZ offered the GAZ-74A project, which was to use the Soviet ZIS-16F or ZIS-80 diesel engines, or the American "Giberson" engine (of 110 hp). It was to be rearmed with the more modern 76.2 mm gun S-1, but the project was abandoned, and only one experimental vehicle was built.

Factory #38 simultaneously offered three different projects: SU-15, SU-16, and SU-38. All these vehicles were to be armed with the 76.2 mm Gun S-15, and they were powered by the GAZ-203 engine (like the T-70 light tank).

The SU-15 was based on the chassis and hull of the SU-12, and was powered by two GAZ-203 engines, and with the slightly improved air-filtering system. The compartment (superstructure) was slightly widened.

The engine, the transmission, and the chassis of the SU-16 was originally taken from the T-70 light tank. However, the protection was increased with 45 mm armor on the front. The compartment was armor-protected from the top and rear as well.

Like the SU-16, the SU-38 self-propelled guns had the chassis and engine taken from the T-70. However, this vehicle was much lighter than the SU-16. It had an all-around protected compartment at the front of the tank (like the SU-152, etc). It was engineered to distribute the load evenly along the chassis.

Comparative trials were performed during the summer of 1943. They showed that the SU-16 was the most successful, but had a poor crew layout. The chassis of both the SU-15 and the SU-38 were overloaded, which led to rapid breakdowns. Nevertheless, the SU-15 was chosen and recommended for mass production after a weight decrease.

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{slide=SU-15M (SU-76)}

SU-15M (SU-76)

While producing the SU-76, the GAZ factory started a modernisation program for the SU-15, as all the critical parts of that vehicle (engine, chassis, transmission, etc) were produced there. The modernised self-propelled gun (factory designation SU-15M) was distinguished from its predecessor by the unprotected compartment from the top and rear. It was powered by two GAZ-202 engines with a common cooling system and transmission.

In August 1943, that SPG successfully passed all trials, and was accepted for service under the SU-76 designation. From October 1, 1943, the mass production of this vehicle began.

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{tab=Combat employment}

Combat Employment

By June 1945, the total production of the SU-76 reached 14,292 - approximately 60% of the total volume of all self-propelled guns produced during the war. It was manufactured in the following factories: Factory #30 in Kirov, Factory #40 in Mytishchi, and the GAZ Factory in Gorkij.

The updated version was delivered to the Army on time, but it left a questionable impression on its crews, and received nicknames such as "Suka" (Bitch) or "Golozhopij Ferdinant" (Naked Ass Ferdinand). Tankers who never fought in the SU-76, but who had judged it from the outside gave such unpleasant nicknames. Tankers who fought in the SU-76 called it "Colombina," which was a somewhat affectionate name. The first negative impressions of the vehicle were formed when these light SP-guns were pressed into service as common tanks.

The first SU-76s were sent to mixed self-propelled artillery regiments and in the summer of 1943, each unit was supposed to have 21 vehicles (four batteries of five vehicles each and one commander's SU-76). Only with time came the realization that the main task of the SU-76 should be close support of the infantry. The task of fighting enemy tanks was left to more powerful artillery systems based on the chassis of the T-34 and the JS-2 tanks. As a result, by the end of 1944, SU-76s were placed into light self-propelled artillery batteries of sixteen vehicles each, which were then part of regular infantry divisions.

Naturally, among the sixty shots that a SU-76 carried, some were armor-piercing. However, its main advantages were its low profile, high mobility, and low ground pressure (0.545 kg/cm²) which allowed it to operate in the marshy and forested areas which had poor ground conditions, in close cooperation with the attacking infantry, and in firing directly at pillboxes and fortified buildings.

Further use of the vehicle in street battles at the end of the war uncovered another disadvantage of the system - the semi-open superstructure of the vehicle, which was roomy and excellent for crew movement, became a mass grave for its crew in case of an infantry grenade explosion. On the other hand, the opened compartment made all types of high-explosive anti-tank (HEAT) ammunition (including weapons such as the "Panzerfaust," the "Faustpatron," and the "Panzerschreck") totally ineffective.

The first batch of SU-76s (25 vehicles) was delivered by January 1st, 1943, and was sent to the self-propelled artillery training school. At the end of January, the first two mixed self-propelled artillery regiments (the 1433rd and the 1434th) were sent to the Volkhov front to assist in the relief of Leningrad, and in March 1943, two more regiments (the 1485th and the 1487th) were formed, and fought on the Western front.

In 1943, a light self-propelled artillery regiment had a full complement of 21 SU-76M. At the end of 1944 to the beginning of 1945, seventy batteries of self-propelled artillery (consisting of sixteen vehicles in each battery) were formed and attached to rifle divisions. In the first half of 1944, light self-propelled artillery brigades of the RGK were formed, and consisted of sixty SU-76M and five T-70s each.

By the end of the war, the Red Army had 119 light self-propelled artillery regiments and seven self-propelled artillery brigades. The Polish army received 130 SU-76M. The SU-76M was used in the design of the ZSU-37 self-propelled anti-aircraft gun, which was armed with a 37 mm automatic anti-aircraft gun. It was manufactured at Factory #40 in Mytishchi (in Moscow suburbs), but it did not see action in World War Two. A total of 75 units were manufactured in 1945 to 1946.

The active service of the SU-76M did not end with the Second World War. The Soviet Army continued to use it through the early 1950's. The 130 vehicles given to the Polish Army were also taken out of service in the mid 1950's. A few dozen SU-76M that North Korea received saw action in the Korean war from which almost none survived.

The story of SU-76 would not be complete without an account of further attempts to modernise it. In December 1943, a SU-74B tank destroyer with a ZIS-2 anti-tank gun was tested, as was a GAZ-75 with an 85 mm D-5-S85A gun in 1944. It had the same 85 mm gun as the SU-85, but it had half its weight and its frontal armor was twice as thick (the SU-85 had 45 mm, and the GAZ-75 had 90 mm of frontal armor). None of those designs ever entered mass production, the main reason being a reluctance to disrupt the production of existing designs for the benefit of only minor improvements, as in the case of new engines, or to completely rework the manufacturing process for a new model.

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