ISU-152
The ISU-152 is a Soviet self-propelled gun developed and used during World War II. It was unofficially nicknamed Zveroboy in response to several large German tanks and guns coming into service, including Tigers and Panthers. Since the ISU-152's gun was mounted in a casemate, aiming it was awkward, and had to be done by repositioning the entire vehicle using the tracks. Therefore, it was used as mobile artillery to support more mobile infantry and armor attacks. It continued service into the 1970s and was used in several campaigns and countries.
History
The beginnings of the ISU-152 came on 24 January 1943, when the first prototype of the SU-152 was unveiled. This was a fully enclosed 152mm gun-howitzer on the KV-1S tank chassis. It was designated Объект 236 . Object 236 was completed in Factory No. 100 in Chelyabinsk, and was tested successfully from 24 January to 7 February 1943. On 14 February the vehicle was adopted and put into production under the KV-14 designation; in April 1943 the designation was changed to SU-152".Although the SU-152 was successful in combat, production of the KV-1S tank chassis was ending, which made the modernisation of the vehicle necessary, using the new IS tank chassis. On 25 May 1943 the administration of Factory No. 100 ordered the modernisation of the SU-152, which included increased armour protection and other improvements. Development began in July 1943, under the supervision of Josef Kotin, the chief designer of Soviet heavy tanks, and G. N. Moskvin as the main designer.
The new design, designated IS-152, was tested from September to November 1943. Testing revealed a large number of deficiencies, which sent it back for further improvement. On 6 November 1943 an order was issued for adoption of the improved variant, under the ISU-152 designation, and in December production began at the Chelyabinsk Kirovsk Plant, replacing the SU-152.
Design
On 15 April 1942, at the plenum of the artillery committee, where the development of assault guns for support of the infantry was discussed, the necessity of also developing assault guns capable of destroying fortified positions was acknowledged. It was intended these assault guns would be armed with a 152.4 mm gun-howitzer and used for penetration of the enemy defence in the offensive operations planned for 1942–1943. This resulted in the development of the Object 236, and eventually the SU-152, which concept was later continued and further developed with the ISU-152.The ISU-152 followed the same design as most other Soviet self-propelled guns. The fully armoured hull was divided into two compartments: fighting compartment for the crew, gun and ammunition in the front of the hull, and engine and transmission in the rear. The gun was mounted slightly to the right of centre with a limited traverse of 12 degrees left and right. The crew consisted of four or five men placed in the superstructure. Three of the crew were to the left of the gun: driver to the front, then gunner and last the loader. The vehicle commander and lockman were to the right: commander to the front and the lockman behind. When the crew consisted of four men, the loading was carried out by the lockman.
The suspension consisted of twelve torsion bars for the six road wheels on either side. The drive sprockets were at the back, and the front idlers were identical to the road wheels. Each track was made up of 90 links. There were three internal fuel tanks, two in the crew area and one in the engine compartment. These were usually supplemented with four unconnected external fuel tanks. 12- and 24-volt electrical power supplies came from a 1 kW generator feeding four accumulator batteries.
For observation from the interior, all roof hatches had periscopes and there were two gun sights: telescopic ST-10 and panoramic. For crew communication a TPU-4-BisF intercom was fitted, and for inter-vehicle communication there was a single 10R or 10RK radio. These were better than Soviet equipment at the start of the war but still inferior to German equivalents.
The crew were given two PPSh submachine guns with 1491 rounds and 20 F-1 grenades for short-range self-defence.
The ISU-152 was armed with the same gun as the SU-152, but it used the hull of the IS-1 tank instead of the KV-1S. Later in the war the ISU-152 was further improved. It used the hull of the IS-2 or IS-2 model 1944 tank, the armour of the mantlet was increased, the gun was replaced by newer variants, a 12.7×108 mm DShK anti-aircraft machine gun was installed by the right forward hatch and later its ammunition capacity increased, the 10R radio set was upgraded to a 10RK and the fuel capacity was increased.
Some ISU-152s were equipped with even larger external fuel tanks, two tanks on the rear hull deck, in addition to the four external fuel tanks — each, maximum — or with two smaller additional external fuel tanks, on the hull rear. This option was probably available for the post-war ISU-152 variants.
Between December 1943 and May 1945, 1,885 ISU-152s were built. Mass production ceased in 1947, with 3,242 vehicles produced in total.
Post-war ISU-152 modernisation included installation of night vision sights, replacing of the V-2IS engine with the V-54K, the 12.7mm machine gun was replaced by a newer variant, the ammunition capacity increased to 30 rounds, additional armor, automotive improvements and significant increase of the main fuel capacity.
Variants
The initial variant was developed in 1943. The factory designation was Object 241. It was armed with the 152.4 mm ML-20S model 1937 gun-howitzer, with a barrel length of over 4.2 metres. This gun had a maximum range of. The armor-piercing round, weighing, had a muzzle velocity of and a maximum penetration of of rolled homogeneous armour at 90° at a range of. The rate of fire was 2-3 rounds/min. The ISU-152 carried 21 rounds of two piece armor-piercing and high explosive ammunition. Later ISU-152 versions had a newer gun with a slightly longer barrel, up to over 4.9 metres, with a maximum range of fire of up to.The ISU-152 had different versions, with changes in the gun, the number of hatches, or the hull. The IS-2 based versions had a thicker gun shield and larger fuel tank. Until May 1944, the main armament was the 152.4 mm ML-20 model 1937 gun-howitzer. The ISU-152 had a rate of fire of 2-3 rounds/min. The early versions had three hatches in the superstructure roof and one emergency hatch at the bottom of the hull behind the driver's seat, which had an armored cover. Later versions had a fourth, round hatch in the superstructure roof on the right, next to the rectangular hatch on the left.