In the history of tank development is not uncommon, when it is a good sample of the armored vehicles appeared too late, to become a serial. Very often this has happened in the final stages of World War II, when part of the military programs cut due to the cessation of hostilities.
Such a "loser" and became a Soviet self-propelled gun An object 704, which was developed under the factory index "Kirovets-2". This machine was a significant step forward compared to the ISU-152, but the end of the war and the revision of the military requirements for a heavy self-propelled guns do not leave the object 704 chance of getting into a series of.
"To improve the ISU"
Q improve characteristics ISU-152 I was raised simultaneously with the first receipt of the information on fighting the use of IS-85. It should immediately be noted, that the level of protection of the machine from the very beginning has been below, than the tank, on the basis of which it was created. Besides, that the thickness of armor frontal part cabin was 90 mm, frontal part angled by 30 degrees from the vertical. This is to protect cabin fire 75-mm anti-tank gun Pak 40 at medium ranges, but the confidence of protection from fire 8.8 cm KwK 36 L/56, installed in heavy tank Pz.Kpfw.Tiger Ausf.E, out of the question.
The essential problem was the fact, that implements protection thickness was only 60-65 mm. Reservation guns ML-20 was rather large, which further reduced the level of protection of the ISU-152 in a front projection.
Sketch of ISU-152 chassis modernizirovannom IS-2, April 1944 of the year.
The first attempt of the ISU-152 was the project of modernization, which was worked NF. Shashmurina. About this development very little is known. known, The car was located aft of the crew compartment, allowing more efficient to place power-caliber gun systems 122 and 152 mm. This machine was created in the same database, and that the IS-2, on the proposal NF. Şaşmurina. However, on sketches is not moved.
Otherwise things were the summer and autumn 1944 of the year. In August, SKB-2 Chelyabinsk Kirov Plant (ÇKZ) It has developed a modernized IS-2 and ISU-152, And to have survived only documentation on the tank. Despite this, understand, than could be different from the production machine ISU-152, not difficult.
The thing is, that the alteration of the engine compartment in the upgraded IP and IMS are the same. Primarily because of the fighting compartment in the MTO cleaned tanks, and the place they were transferred batteries. Also changed the cooling system and the exhaust system. Despite the fact that both machines work began back in August 1944 of the year, Test upgraded ISU-152 was released in October. TO 16 November car passed 1000 km. However, this work resulted in, because the SKB-2 CHKZ already hard at work on more promising modernization of the IP chassis.
The first prototype of the ML-20cm modernized system. Despite the fact that the first prototype gun was ready to spring more 1944 of the year, SAU in his set only a year later.
Modernization was not only on the chassis. By the end 1943 Artillery Committee, the GAC spacecraft began to think about, that in the current form of 152-mm howitzer-gun ML-20c is not entirely successful as a self-propelled system. Some comic these conclusions gives the fact, that is the same Artkom GAU satellites at one time rejected №8 plant project, known as 20-ZIK. F. F.. Petrov, led the development of ZIK-20, in the summer 1942 year proposed to remove from the ML-20 muzzle brake, as well as several alter system, simplifying its installation in ACS.
In the autumn 1942 year, this idea is not supported, and at the end 1943 , she appeared as an initiative Artkoma GAU SC. Now it proposed to dismantle the muzzle brake, enter wedges, change the cradle and the frame.
Job instructed DB-172, which with 13 January 1944 The beginning of work on the project, received the designation ML-20cm. He directed the work of the chief designer of OKB-172 on the ground artillery M.Yu.. Tsyrulnikov. The draft ML-20cm partially complied SC GAU: muzzle brake eliminated, cradle and shortened recoil device, and introduced recoil brake simpler construction.
The same system after the installation in the "Kirovets-2". Unlike the original version, when installed in a new car was delivered coaxial machine gun DShKM.
Detailed documentation on the MLS-20cm was completed by 1 Martha 1944 of the year. TO 10 March prototype gun was manufactured by the №172. The first shooting held 11 Martha, and after 33 shots filmed with the test system due to unsatisfactory performance shutter.
During the tests, March and April 1944 year manufacturing defects have been found. Nevertheless 14 April ML-20cm withstood the test of high-speed shooting 60 shots, producing them for 39 minutes instead of hours laid. In total for March-May 1944 , the gun produced 249 shots, of them 196 - enhanced charge. rate reached 2,9 shots per minute.
According to the results of tests planned to be installed in a self-propelled gun, but this has not happened. As for test tools, they continued to plant №172 till September 1944 of the year. At this time, between NKTP, GBTU CA, NKTP and GAC were disputes regarding the tools. Finally 2 October 1944 the team to send the ML-20cm was given to the Kirov Plant and set in ISU-152.
By mid-October, when the cannon was brought to Chelyabinsk, It revealed, it came in the form of unfinished. In late December, GAU spacecraft delivered to the plant №172 issue of the urgent need to finalize the instruments and send designers on CHKZ. In spite of this plant №172 representatives arrived in Chelyabinsk only in mid-February 1945 of the year. By the time the situation with the modernization of the ISU has reached a new level.
Very big upgrade
To the moment, when upgraded ISU-152 sample program skated factory tests, his fate was sealed. The thing is, what to 16 November 1944 year collected the first sample tank, who had originally factory designation A-701. This machine, which he was the lead engineer MF. BAL, is a further development of the theme "Big Modernization" IS-2. From the IS-2 were taken engine, transmission elements and radiators, Besides, CB factory full use of the achievements of the first sample of IP-2 is a great modernization.
Production of finished cars to 23 November, Weighing showed a lot of fighting in 48 t. "Sample A", as it was called in the summary of work on CHKZ, later I received the designation "Object 703". By the end of December, the car became known as the IS-3, while in the original documentation was used the designation "Kirovets-1". The same designation is often used in the further correspondence on GBTU spacecraft and NKTP.
"Kirovec-2" on Nibte Polygon, summer 1945 of the year.
According to the results of tests extensive list of comments were made up, which is required to eliminate "Kirov workers-1" subsequent samples. Also changed the nose piece housing ("Pike nose"), which was taken from the EC-2U drafting CB factory №100. Nevertheless, it became apparent, BAL project that is the very replacement of the IS-2, which have been waiting for. On CHKZ begun preparatory work for the production of a pilot batch tank, which the 29 Martha 1945 of the year, after testing a prototype of the second, adopted by the Red Army as the IS-3.
Even earlier, at first 1945 of the year, restart the development of self-propelled chassis with "Kirov workers-1". As is the case with ISU-152, He was the lead engineer of the machine LS. Troianov. In the correspondence of the plant, this machine has passed both "Kirovec-2", while the car has received the drawing index 704 (also use the notation An object 704). In Russian literature, this machine is often referred to as the ISU-152 obr.1945 year, but it is nothing more than the post-war "invention". It is very likely come up with the index Kubinka, where the object 704 It is still kept as a museum piece.
Similarly, IS-3, which is very different from the IS-2, ACS-based 703rd facility is also significantly different from the ISU-152.
For the first time, "Kirovets-2" appeared in the correspondence in February 1945 of the year. On the development of new self-propelled CHKZ said in his report to SP. Gurenko, chief designer of the plant №172. He led the very commission, We have been waiting in Chelyabinsk More from December 1944 of the year. Trip plant constructors №172 took place in the period from 14 by 20 February 1945 of the year. By that time, SKB-2 CHKZ not just prepare working drawings "Kirov workers-2", no i dropped them to institute №200.
By mid-February the body of the machine arrived at CHKZ, which went assembly units. The housing of the new self-propelled radically different from the ISU-152, under which it was originally designed ML-20cm. This was the case and gun installation. In this regard, it was necessary to make changes in design tools, which for several months has been on CHKZ. Lower cradle angle obliquely cut off, a rollback on the brake shortened 70 mm. These changes brought himself Kirov factory, in this work are consistent with the plant №172.
3 on March CHKZ held a technical meeting, which discussed the installation of ML-20cm in "Kirovets-2". It was decided to put the armor protection improved system and form thickened up 100-150 mm. Instead panoramic sight 52-CM-504A decided to put the panorama from 76mm cannon regiment sample 1943 year as a more simple and compact.
Changed and telescopic sight: instead of bulky ST-10 decided to put a more compact and easy to use TS-17. Besides, "Kirovets-2" became the first Soviet heavy self-propelled guns, which had the twin machine gun. It was decided to make the installation coupled with a gun heavy machine gun DShKM, We put him right from the gun. Finally, modifications rotary mechanism implements.
"Kirovec-2" and has some differences from the "1-Kirov workers', and the serial IC-3 in some detail - especially nadmotornoy plate.
The fineness of the time was that, that the planned remodel serial ML-20cm. This was agreed at the Kirov plant, and the plant №172, but the leadership of the SC GAU had an opinion on the matter. between GAU, GBTU spacecraft and IEC unfolded correspondence, which lasted for a few months. As a result, time was lost, to "Kirovets-2" cannon installed only in mid-June 1945 of the year, while the chassis itself was ready to spring more. Despite the fact that the basis for the ACS was "Kirovets-1", a complete copy of its chassis "Kirov workers-2" call incorrectly. Wherein nadmotornoy plate design, and tailpipes made by object type 701.
The most important change was the fighting compartment. The main objective in its design is to bring protection to the IS-3 level, what designers coped. Thickness cutting his forehead reached 120 mm, The result is a reliable protection of the 88-mm cannon Pak 43 L/71. The thickness of the cutting beads reached 90 mm, wherein the sheets are positioned under the rational angles. Substantial efforts and armor protection system. Thickness increased to mobile bookings 160 mm, ie became almost three times thicker bookings ML-20c.
Inside the crew compartment.
Distinguished not only a form of felling, but its overall concept. First of all, a driver is now placed so, that did not have viewing devices in the frontal cutting. His workplace endured the most up, so that in the stowed position, he drove, leaning out of the sunroof, - is significantly increased visibility.
In a combat situation a driver used periscopes in the hatch, who had a circular rotation. The same hatch had commander. A total number of hatches on the roof of the cabin rose to five, one of them was meant for weapons panoramic sight. Due to the expansion board sheets cutting crew compartment was a bit roomier, with an overall height of the machine compared to the ISU-152 was lower on 5 cm. Despite the significant increase in the level of protection, combat weight increased less significantly, reaching 47-48 t.
A car, drowned in approvals
according to correspondence, finally collected "Kirovets-2" by mid-June 1945 of the year. Further, the machine went to Moscow plant №37, and from there to NIBT Polygon. There self-propelled artillery waited send test. Sea trials NIBT Landfill did not hold, since it was no indication. However, at the site amounted to a brief description of the machine. The testers noted the increased armor protection.
Often in publications, dedicated "Kirov workers-2", states, that experts have recognized NIBT Polygon fighting compartment close, but in the summer 1945 year estimate was quite different: "The layout of the installation jobs commander and especially the driver offers the convenience and rationality".
In view of the various approvals artillery tests "Kirov workers-2" passed in the autumn 1945 of the year.
The situation around "Kirov workers-2" looked somewhat comical since, that the People's Commissariat of weapons requested to send a car to the Leningrad Artillery Research testing ground (ANIOP). This directive was a logical, as it needed to test the car first of all weapons, which began with the development of. At the same time, "Kirovets-2" is still in Kubinka without any movement.
Even endorsed by the IEC program tests the ML-20cm and a letter Ustinov, dating from the end of July 1945 of the year, initially not particularly helped. In August, the testing agreed GAU SC Guide, and "Kirovec-2" relegated by the ANIOP. However, neither in August, or in September 1945 year, no trials have been conducted. This time the culprits were the representatives of the plant №172, who did not go to the landfill.
Finally, to 24 September, representatives of the profit of the plant, but only in order, to a few days to go, leaving a designer, who had no authority to conduct the test. In this way, only due to the various delays and approvals lost six months. Typically, such action to anything good does not, and the story of "Kirov workers-2" is no exception.
Side view, antiaircraft gun zachehlon.
According to the results of all tests approvals and delays stretched to 25 September 13 November 1945 of the year. From the plant №172 on their profits Kuznetsov and Senior Design Engineer Nazarov. Total for this period were made 65 shots on a full charge, and 244 - to charge enhanced. Shooting was successful, and sometimes the case, the problem of extraction cartridges were connected to their deformation, which did not have a gun no relation. One of the few problems, which indicated in the tests the ML-2cm, was the need for the introduction flap in mobile bookings to access the air valve recoil brake.
Accolades to the gun was more. Unambiguous advantage cited the lack of a muzzle brake, which reduced the unmasking when shooting. true, when shooting broke spotlight, as a result, it was decided to put it on the shock absorber. Also praised the trigger, endowed with a lever escapement and electric. And received high evaluation sight TS-17, more comfortable, than ST-10. When shooting almost no sight sbivaemosti.
Anti-aircraft guns in firing position.
Evaluation of the crew compartment "Kirov workers-2" was the same, like test NIBT Polygon. Convenience operation of the driver recognized higher, What the SU-152 and ISU-152, And this applies not only driving, but also access. More higher grade was awarded to place commander. Unlike SU-152 and ISU-152, he sat on a course of movement of the machine, not hip. It was significantly higher visibility, praised and onions, rotates around its axis. The gunner also got more comfortable workplace.
Worse was the situation with the Charges. The Commission recognized, what from 20 shells conveniently charge 12, located on the left side. it was difficult to get to the rest, however, Similar problems were and ISU-152. In terms of charging ramps cutting recognized bad idea, because it reduces the ammunition. The Commission proposed on rational inclination angles refuse. It was the least comfortable working conditions castle (however, it is worth noting, that ISU-152 were observed similar difficulties).
View from the stern. Tests "Kirovets-2" passed quite successfully, but by the end of 1945 year change of priorities, with the result that the car was simply not needed.
Self-propelled "Kirovets-2" and an instrument ML-20cm recognized withstand the test. The plans NIBT Polygon item appeared on the sea trials, but precious time was lost. By the end 1945 at GBTU spacecraft and GAU changed requirements as a heavy self-propelled guns, and the guns, are required to put them: military, what is called, We slept and saw a heavy self-propelled gun based on the Object 701.
EC-3 in GBTU spacecraft looked askance more spring 1945 of the year, Considering this tank yesterday afternoon. Only problem with the fine-tuning Facility 701 led to a wise decision to start IS-3 in series.
Spring and summer 1945 of the year, on the military situation background, "Kirovets-2" still had a chance to go in the series, but by the end of the year the situation has changed. Release of heavy self-propelled guns folded, Soviet tank builders started to think long-term. This prospect is the object of the chassis 701, which in April 1946 years have adopted as the IS-4. In such circumstances, "Kirovets-2" has lost any chance to run in the series.
Later it became clear, EC-4 has not turned, and dreams of ACS based on it went no further large-scale projects and layouts. As a result, the following became the object of heavy self-propelled guns 268, which is kind of the same fate as "Kirov workers-2": delays led to, that this car did not have any chance to serial production.
/Yuri Pasholok, warspot.ru/
