CHAPTER 6. Birth of the Zveroboy—the “Beast Killer”
Just when the Chelyabinsk Kirov Factory began working on a heavy SP gun is not known for certain. All we can be certain of is that the Kirov Factory did not originate the design of the ZIK-20’s competitor. Moreover, no matter what project was placed in service, it would have to be produced in Chelyabinsk. The originator of work on the heavy SP gun at the Chelyabinsk Kirov Factory is clear from Factory No. 100’s report covering the period from September 15 to October 1, 1942:
The KV-7 tank
The tank with twin artillery systems has been rejected. The GAU suggested that the Kirov Factory mount a single ML-20 artillery system on this vehicle. The system has arrived at Factory No. 100. The designers are preparing drawings for this installation, after which they will begin constructing a wooden model for presentation to the GAU commission.{1}
L. S. Troyanov headed up design of the SP gun. Lev Sergeyevich was the most experienced Soviet designer of all those working on self-propelled artillery. He began with the SU-5, which was based on the T-26; then came the SU-14, the T-100Y, and the T-100Z. It should be noted that Troyanov’s initial development was not an analog of the ZIK-20. According to N. F. Shashmurin’s memoir, the initial SP gun concept was faithful to the GAU’s requirement for a “bunker buster based on a chassis incorporating assemblies from the KV tank:
Concerning development of the SU-152. It mattered which chassis we used for the task. Our team was joined by Engineer L. S. Troyanov, who produced a conceptual layout on a chassis with eight pairs of road wheels and used components from the KV-1S tank.
The year 1942 was drawing to a close. Clearly, that design solution was sheer nonsense. The only solution we liked was one that retained the KV-1S chassis. Kotin came to my office and drew a picture—a 152 mm gun mounted on a KV-1S. Instead of a turret, it had a KV-7-type superstructure. That, of course, was the only proper solution. He gave us an assignment: “Determine the feasibility of that option by 3:00 AM.” He left a sketch of the gun that G. N. Rybin had brought him from F. F. Petrov. We had a layout ready by morning. The designers were N. T. Fedorchuk and M. I. Zeltser. We ended up with a severely overloaded front suspension and a gun that stuck out too far in front. No other ideas came out of a meeting of the lead designers. The main burden of fulfilling this task fell on the team led by V. I. Tarotko and the artillerymen under F. F. Petrov. The KV-1S vehicle and primary production were retained. The total amount of work involved in designing and manufacturing the SU-152 prototype wasn’t excessive, and it was ready a month later.
The documentation largely bears out Shashmurin’s description. Unfortunately, little correspondence remains from this period (November–December 1942). It is possible that some documents, including Troyanov’s initial design, have been retained in GAU files that have yet to be declassified. Incidentally, Shashmurin clearly understated Troyanov’s role in the project: he is listed as “Senior Project Engineer” on the system drawings. The 1:10 scale wooden model and the design documentation for the SP gun were produced towards the end of December 1942. The project was assigned the designation KV-14, and the drawings were given the number 236 (in the summer of 1943, the project began being called Object 236). Correspondence dating from early 1943 also occasionally included references to the designation SU-14.
As mentioned previously, the SP gun models were scheduled to be displayed on January 3, 1943. A. A. Goreglyad and Zh. Ya. Kotin (of the People’s Commissariat of the Tank Industry) and P. F. Solomonov (of the Main Artillery Directorate) were authorized to evaluate the projects. It is interesting that the Kirov Factory’s SKB-2 submitted not one project, but two, each based on a different hull. The following conclusions were drawn from the examination of the projects:
1) The project that Factory No. 9 submitted for review was more complete (to include engineering drawings) than the Kirov Factory project.
2) Factory No. 9’s project required significant modification of the 152 mm gun-howitzer model 1937 (removal of the muzzle brake, a new recoil mechanism, etc.), which was inconsistent with GAU’s operational requirement.
3) The weight of the SP gun designed by Factory No. 9 has increased to 47.5–48 tonnes, and it is larger.
4) The correction of the above-listed deficiencies (paragraphs 2 and 3) required major modifications and revision of the engineering drawings of both the hull and the system.
5) Engineering drawings have been only partially completed for the Kirov Factory’s two versions of its project, and some assemblies (e.g., the frame, the trunnion ring, and the elevation mechanism) required significant modification. For example, the elevation mechanism was taken from the ZIS-5 and did not meet the strength requirements.
6) The Kirov Factory’s first version (which lengthens the hull by 450 mm) caused problems with full-scale production because its side plates could not be manufactured on Factory No. 200’s unit-type machine tools. In addition, the placement of the three front road wheels (which increased the spacing between them) was controversial because it reduced the vehicle’s mobility, especially in swampy terrain and during the spring and fall thaws.
7) The Kirov Factory’s second version introduced the fewest modifications in full-scale artillery and tank production and was sensible in terms of its shape, fighting compartment layout, weight, and dimensions, but it required a large number of drawings to be revised.
The Commission concluded that work on the Kirov Factory’s second version should proceed, and that engineering drawings should be prepared and checked by constructing a wooden mockup.{2}
Needless to say, Petrov was very upset by this outcome. After Factory No. 8 was split in two, the main task of Petrov’s design bureau was development of tank and howitzer systems, and the ZIK-20 became something of a burden. In addition, as already mentioned, the system was going to be produced in Chelyabinsk anyway. Even after the KV-14 project won out, Petrov’s role in the SP gun did not diminish greatly, because he had developed the ML-20 gun-howitzer that was to be mounted on the Chelyabinsk vehicle. The ML-20 modification minus muzzle brake proposed in the fall of 1942 was more suitable, but at that point it was much more important to have as little impact on the design as possible in order not to delay production of the KV-14.
The Commission’s decision finally put into motion a mechanism that began inexorably ticking down to the start-up of production on the heavy SP gun. The very next day after the display, Stalin signed State Defense Committee Decree No. 2692 “On Manufacture of a Prototype 152 mm Self-Propelled Gun Based on the KV-1S Tank Chassis,” which established a deadline for building the prototype:
1. The People’s Commissar of the Tank Industry (Comrade Zaltsman), the director of the Kirov Factory (Comrade Goreglyad), the director of Factory No. 200 (Comrade Shcherbakov), and the chief designer of the People’s Commissariat of the Tank Industry (Comrade Kotin) shall manufacture a prototype of a self-propelled gun with a 152 mm gunhowitzer model 1937 (ML-20) based on the KV-1S tank chassis and provide it for proving-ground tests by January 31, 1943.
2. The People’s Commissar of Arms (Comrade Ustinov), the director of Factory No. 172 (Comrade Vykhovsky), the chief designer of Factory No. 172 (Comrade Gurenko), and the chief designer of Factory No. 9 (Comrade Petrov) shall manufacture and provide to the Kirov Factory a 152 mm gun-howitzer model 1937 (ML-20) adapted for mounting on a KV-1S tank chassis by January 23, 1943.
3. The overall development of the project, the modification of the 152-millimeter gun-howitzer model 1937 (ML-20) for mounting on the vehicle, and the allotment of mounting-part production to factories shall be done at the Kirov Factory jointly by designers of the People’s Commissariat of the Tank Industry and the People’s Commissariat of Arms, with the involvement of the following GAU engineers: Eng. Col. Komarov and Eng. Maj. Solomonov.
4. The following basic characteristics of the 152 mm SP gun based on a KV-1S tank chassis shall apply to the design:
a) The combat weight with ammunition, fuel, and crew shall not exceed 45.5 tonnes;
b) The vehicle shall have at least 20 rounds of ammunition on board;
c) The armor thickness of the fighting compartment shall be 60 mm;
d) The thickness of the frontal armor of the fighting compartment shall be 60–75 mm;
e) The height of the fighting compartment shall be at least 1700 mm
f) The rate of fire shall be 3–4 rounds per minute.
By January 6, 1943, the chief of the GAU (Comrade Yakovlev) shall issue an operational requirement to the People’s Commissariat of the Tank Industry for guidance in manufacturing the prototype.
5. The Main Artillery Directorate, the Main Directorate of the Chief of Artillery, and the Main Armored Forces Directorate shall organize and carry out proving-ground tests on the prototype at the artillery range near the city of Chelyabinsk over a 7-day period beginning the day it arrives at the test range.
6. The chief of the Directorate of Fuels and Lubricants (Comrade Kormilitsin) shall support the tests with fuel at the request of the GAU.
7. The results of the tests shall be reported to the State Defense Committee within three days after completion.
8. The People’s Commissariat of the Tank Industry (Comrade Zaltsman) and the People’s Commissariat of Arms (Comrade Ustinov) shall immediately begin production engineering for the 152 mm self-propelled gun so that mass production can begin as soon as the prototype is approved.{3}
The Chelyabinsk Kirov Factory’s deadlines for drafting the documentation and manufacturing the prototype were tight, but realistic. The SU-12 and SU-35 SP guns had been developed at a similar pace two months prior to that, and their developers had more or less met their deadlines. The Kirov Factory’s team was now facing the same task.
Meanwhile, events were proceeding precisely on schedule. On January 5, I. M. Zaltsman, People’s Commissar of the Tank Industry, issued Order No. 6ss “On Manufacturing the Prototype of the 152 mm Self-Propelled Gun Based on the KV-1S Tank Chassis.” According to the order, Chief Designer Zh. Ya. Kotin was to issue the drawings for the system by the 10th. Factory No. 200 was to supply a finished hull for assembly by January 18, and the deadline for manufacture of the KV-14 was set for January 25. Plans called for factory testing of the SP gun to be complete by the 29th and for it to be provided for proving-ground tests on February 1. The modified ML-20 gunhowitzer was to be received for installation in the KV-14 on January 23.
As stated in the decree, on January 6, 1943, GAU Artillery Committee Chairman V. I. Khokhlov (who by that time had been promoted to Lieutenant General of Artillery) sent off two copies of the operational requirement for the “152 mm self-propelled gun based on a KV-1S tank chassis.” He sent the requirement, which had been approved by GAU Chief Col. Gen. of Artillery N. D. Yakovlev, to the Kirov Factory and to People’s Commissar of the Tank Industry I. M. Zaltsman:
I. Role
1. The 152 mm self-propelled gun is intended for destroying bunkers, earth-and-timber emplacements, and other strong field fortifications by direct fire from close range during breakthroughs of enemy defenses, as well as for combating enemy artillery and shelling his rear areas.
II. Main specifications
1. The self-propelled gun is to be produced by installing the tipping parts of the 152 mm gun-howitzer model 1937 in a fixed turret that, in turn, is to be mounted on a KV-1S tank chassis.
2. The weight of a fully-fueled self-propelled gun with ammunition and crew must not exceed 45.5 tonnes.
3. The thicknesses of the fixed turret armor plates must be as follows:
a) Front: 60–75 mm;
b) Equivalent to that of the KV-1S tank on the side and rear, i.e., 60 mm;
c) Top: 20 mm
4. The basic load of the self-propelled gun must comprise at least 20 rounds.
5. The height of the fighting compartment above the floor must be at least 1700 mm.
III. Artillery system specifications
The self-propelled gun must meet the following specifications:
1. Angles of fire:
a) Elevation: from -3° to +20°
b) Traverse: 6° to each side
2. The practical rate of fire with correction of aim: 3–4 rounds per minute.
3. Constant recoil: 850 mm (achieved by appropriate securing of the counter-rod)
4. The effort required to operate the gun laying mechanism flywheels must not exceed that of the gun-howitzer in service, namely:
a) Elevation: 8 kg;
b) Traverse: 5 kg.
5. The sights must support both direct fire from unconcealed positions and indirect fire from cover. A sight must be installed such that the panoramic sight’s objective lens extends above the turret roof. Install a headrest to facilitate the work of the gunner.
6. Loading gear: a special tray like that used in the 122 mm self-propelled gun produced by Factory No. 592.
7. Firing gear: hand- and foot-operated
8. Barrier
To protect the gun crew from recoiling parts, a special barrier must be provided that does not hinder loading.
9. Balance
The muzzle brake may be removed from the barrel in order that the effort required to operate the gun laying mechanism flywheels does not exceed that on the model 1937 gun-howitzer, provided such is supported by calculations of the strength of the recoil mechanisms. In this case, the mounting parts of the gun must be designed for greater recoil resistance.
10. The position of the traversing mechanism flywheel relative to the panoramic sight eyepiece and the gunner’s seat must be such that it facilitates the job of the gunner without removing his eye from the eyepiece. The existing traversing mechanism may be replaced with a helical mechanism.
11. The traversing mechanism flywheel may be replaced by a naval handwheel.
12. The recoil mechanisms that extend outside the turret must be shielded by a turret thickness of 30–35 mm, and the frontal part must be shielded by 75 mm of armor. The front must have a hatch for access to the recoil mechanisms.
13. The howitzer installation must support easy loading at all allowable angles of elevation and traverse.
14. The tipping parts must be capable of being secured in the travel position from inside the vehicle to prevent the gun from moving vertically or horizontally.
15. SP gun crew: 6:
a) gun commander; b) gunner; c) loader; d) breechblock operator; e) radio operator; f) driver-mechanic
IV. Hull and vehicle requirements
1. The fixed turret that replaces the rotating turret must be strong and support easy and safe servicing of the gun and the required rate of fire.
2. The space over the tracks must be used to create a spacious fighting compartment.
3. The ammunition storage rack must be strong and support free and easy removal of round components in order to achieve the required rate of fire.
4. The placement of rounds in the fighting compartment must be consistent with the division of labor between the loader and the breechblock operator: the loader prepares and inserts a projectile into the chamber, and the breechblock operator opens and closes the breech and inserts the case.
5. The rear part of the roof and the rear of the fighting compartment must have a hatch with doors that open for entry and exit by the gun crew and for loading ammunition.
6. There must be a ventilation port with a cover that closes in the rear part of the fighting compartment for ventilation.
7. The mantlet must overlap gaps at all angles of elevation and traverse.
8. The rear walls of the turret and the front plate must have openings with armor plugs for firing the PPSh submachine guns.
9. Install a PTK panoramic sight for use by the commander to observe the battlefield and adjust fire. Provide a hatch in the roof of the firing compartment in front of the PTK for manually wiping the prism head. This opening will also be used for signaling with flags and discharging the flare gun.
10. Provide observation slits in the front and side walls of the fighting compartment as additional means of monitoring the terrain.
11. Provide each gun crew member with a seat for use while the vehicle is in motion.
12. The following communications equipment must be installed:
a) For external communication: a 9-R radio;
b) For internal communication: a TPU-3F intercom system.
13. Fighting compartment lighting must enable firing with the hatches closed.
Sight scales not illuminated by the roof light and the panoramic sight crosshairs must be illuminated separately and be powered by the vehicle electrical system.
14. The interior of the fighting compartment must have places for securing the spare parts, tools, and accessories (SPT&A) kit needed during firing; cabinets for the crew’s dry rations; and a tank for drinking water.
15. In addition to its artillery ordnance, the vehicle must be equipped with two PPSh submachine guns with 1500 rounds and 10 hand grenades, and means of securing them in the fighting compartment must be provided.
16. A special rack must be mounted on the vehicle outside the fighting compartment to carry the following items:
a) A vehicle-transportable SPT&A kit for the vehicle;
b) Entrenching tools: ax, saw, crowbar, shovels (2), pickaxe.
V. Combat specifications for the self-propelled gun
1. The self-propelled gun fires from a stationary position or from short halts. Firing on the move is allowed as an exception.
2. The self-propelled gun must be at least as accurate as the tabular accuracy of the 152 mm gun-howitzer model 1937 that is in service.
3. The self-propelled gun must be stable when fired at all elevation and traverse angles, on side slopes, and on uphill and downhill slopes.
4. The handling characteristics of the self-propelled gun, including its mobility, trafficability, etc., are determined by the KV-1S tank chassis with its weight increased to 45.5 tonnes.
VI. Additional guidance
During project development and prototype manufacture, retain as much as possible of the production facilities for the 152 mm gun-howitzer model 1937 and the KV-1S tank. Shortcuts that interfere with established production lines shall not be allowed. Only changes that are absolutely necessary shall be permitted. The howitzer recoil mechanisms shall be used without change.{4}
Work got underway at SKB-2 as soon as they received the operational requirement for the SP gun. According to reports received by GABTU, the first drawings for building the prototype were provided on January 8, and the last on the 10th. The flowchart for the parts was ready the following day. Meanwhile, work on the model was already underway. Models of the system’s mantlet were finished on the 14th, and the TV-14 model as a whole was done on the 17th. The model was approved that same day. On January 19, Factory No. 200, which was producing the hull, had the plates for the superstructure ready and began installing them on the KV-1S hull that same day. The completed hull for the prototype arrived the next morning from Factory No. 200. Assembly began that same day: alignment of the engine and the transmission was completed, and the balancing arms and torsion bars were installed.
At the same time, Factory No. 172 was preparing to manufacture the self-propelled version of the ML-20 152 mm gun-howitzer. To facilitate use of the documentation, on January 11, 1943, the self-propelled version of the gun was renamed the ML-20S (the designations ML-20-S and ML-20s were also used). The system was mounted on a frame with armor protection and a massive mantlet. The mantlet had a special opening with a cover for performing maintenance on the recoil mechanisms. A hydraulic pump was used for adding fluid to the recoil devices. The front hull plate of the KV-14 had a special recess where the pump was placed while the recoil mechanisms were being serviced. Because removal of the muzzle brake would require a great deal of work, the barrel was left unchanged.
The main modification made to the towed version of the ML-20S was the installation of the T-9 (TOD-9) telescopic sight, which had originally been developed for the KV-2 heavy tank. The T-9 was a modified KT-1 (a casemate telescopic sight) for casemate emplacement of the DOT-4 and included a prism, which gave it its characteristic “elbow.” The Hertz panoramic sight (PG-1) was retained for firing from cover. As specified by the requirement, the rollback mechanism was removed and the counter-rod was fixed in the short recoil position. Sector-type elevation and traversing mechanisms with worm gears were added. In addition, a loading tray was attached to the carriage to facilitate loading. It also served as a barrier for the loader.
It should be noted that the use of the T-9 sight from the KV-2 was a temporary solution. The system assembled for installation on the KV-14 prototype was equipped with a T-10 sight with scales inscribed for the ML-20’s ballistics. However, time was needed to begin manufacturing the T-10, so the first KV-14’s were equipped with a T-9, which were readily available after production of the KV-2 ended.
The system underwent factory testing at Factory No. 172’s test range on January 21. In all, 58 rounds were fired, 5 with reduced charge, 3 with a full charge, and 50 with supercharge. The system functioned without a hitch during testing; the shift in elevation during firing was two thousandths of a degree. No warping was found after the proof tests, and the effort required to operate the flywheels was within normal limits.
Assembly of the KV-14 prototype was essentially finished by the morning of January 23. The only delay was due to the gun system, which arrived that evening. Mounting of the gun took all night, and the work of assembly ended the next day, earlier than expected. As expected, when assembly was complete, the KV-14 with serial number 3011 was sent off for factory tests, which concluded on January 29. Exactly a year had passed since Ginsberg signed the operational requirement to mount a 152 mm howitzer in a KV-7.
In developing the KV-14, the SKB-2 team took maximum advantage of its experience in building the KV-7. The height of the superstructure remained unchanged, but the interior space was increased by moving the front plate much further forward as compared to the KV-7. As on the KV-7, a special skirt was added to the lower part of the mantlet to prevent the system from jamming on the upper front plate of the hull. For improved ballistic protection, the side plates of the superstructure were angled in both the vertical and the horizontal planes. On the one hand, this solution increased the probability of a ricochet, but on the other, it cut into the interior space. In accordance with the requirement, submachine gun ports were installed in the superstructure’s front and rear plates, and a double hatch was installed in the rear for loading ammunition and for crew access to the fighting compartment. In addition to the rear hatch, there were hatches in the superstructure roof for entry by the loader and commander (the commander’s hatch had a signal port). In addition, a PTK panoramic sight was mounted in front of the commander’s hatch. Vision blocks with mirrors similar to those used in the KV-1’s turret were installed to improve visibility around the superstructure. Four vision blocks were originally planned, but a vision block for observation to the right was added to the prototype and the production vehicles and was used by the breechblock operator. For a variety of reasons some of the vision blocks were located relatively far from the edge of the superstructure roof, creating large blind zones around the vehicle.
In developing the new SP gun, its creators had to deviate somewhat from the operational requirement. According to specifications, the KV-14 crew was supposed to consist of six men, but the fighting compartment had no room for the radio operator. That problem was solved by combining the functions of the commander and radio operator. The 9-R radio was placed in front of the commander’s position. In addition, the size of the fighting compartment prevented use of the standard fuel tanks from the KV-1. Instead, fuel tanks with a total capacity of 480 liters were placed along the sides of the superstructure. That location greatly increased the risk that they would be struck by enemy shells, but with such a compact layout, there was no other place to locate the fuel tanks. Some deviations from the Kirov Factory design bureau’s initial design were also required. The GABTU required that tanks and SP guns be equipped with handrails for riders to hold onto. Handrails were not originally part of the KV-14 design, but the prototype had them.
The strict specifications regarding the fighting compartment’s interior dimensions meant the designers had a hard time finding a place to put the ammunition. The main ammunition storage rack was located on the left side of the superstructure, and some of the rounds were located under the gun. With this arrangement, getting at the second group of shells proved challenging, but there was no other place to put 20 rounds. On the other hand, the fighting compartment was relatively spacious. Considering that the average height of a tanker was 160–170 cm, the crew could stand inside the KV-14 without bending. The overall height of the vehicle was 2450 mm; in other words, it was on a level with the T-34 and 20 cm lower than the KV-1S. In addition, to ease movement of crewmembers within the fighting compartment, the commander, loader, and breechblock operator had folding seats.
All things considered, the Chelyabinsk vehicle was unique. No other army had a weapon system with its combination of relative compactness, good armor protection, and powerful weaponry. Instead of the narrowly specialized machine for attacking fortifications that the artillerymen wanted, they got a general-purpose assault SP gun that went down in history as the “Beast Killer.” However, the KV-14 would not acquire its reputation as the scourge of German armor until the summer of 1943; first, it had to undergo proving-ground tests, which were scheduled for early February.
According to the test program, the KV-14 was to traverse a difficult 200 km route, and plans called for the ML-20 to fire 296 rounds. The testing took place at the Chebarkul Test Range. In fact, the route from Chelyabinsk to the test range and back constituted the road test. It did not travel 200 km, however, because the distance to the test range was 85 km, and it traveled 88 km on the road back.
The trip to the test range took place under very harsh conditions. Not only was the highway covered with snow, the outside temperature was -42°C. On top of that, there was water in the fuel, which caused the engine to stall frequently. As a result, it took the KV-14 13 hours to cover the 85 kilometers.
The firing program was cut short: instead of 296 rounds, 234 were fired, of which 100 were supercharges. The firing for durability revealed no warping in the gun or the mounting parts.
An average of 2.8 rounds per minute was achieved during the rate-of-fire test using the first row of the storage rack. This was below the specified rate, but it was not bad for such a high-caliber gun. Firing was carried out with the hatches closed and the engine running. Depending on the rack used, reloading took from 16 to 30 seconds. The SP gun recoiled 70 to 250 mm during firing, and the stern or bow dropped 10–80 mm. The test program also included firing from short halts. A series of firing from halts at ranges of 800, 600, 400, and 200 m was carried out. Five rounds were fired after each halt. Firing accuracy was acceptable, especially for an SP gun intended for engaging enemy fortifications. It should also be considered that the vehicle was a prototype, and not all of the bugs had been worked out of its individual assemblies by that point in time.
When the firing trials were complete, the KV-14 was driven back to Chelyabinsk. At -16°C, the outside temperature was quite reasonable for early January. As before, the highway was snow-covered, which increased fuel consumption to 4 kg per kilometer. Nevertheless, the vehicle covered the 88 km return route much more quickly—in 6.8 hours. It reached an operating speed of 13 km/h and a cruising speed of 20 km/h. There were no failures in the engine or transmission during either trip. The mechanism securing the gun in travel position worked properly. No special tests were performed during the trip to the test range and back because the SP gun’s chassis was the same as that of the KV-1S. In all, the entire test cycle took five days—from the 1st through the 5th of February, 1943.
A commission headed by GAU Artillery Committee chief V. I. Khokhlov (who at that time held the rank of lieutenant general) drew the following conclusions on the basis of the test results:
The 152 mm self-propelled gun prototype presented for testing satisfies the operational requirement except for rate of fire, during which the maximum value achieved was 2.8 rounds per minute in the third series of 10 shots using shells and cases from the nearest storage rack with the gun in optimum position, compared to 3–4 rounds per minute as required by the operational requirement.
We concur with reducing the crew size to four men since external communications by radio can be assigned to the gun commander.
The accuracy of fire by the self-propelled gun obtained both as a result of its special definition and during firing from short halts per the rate-of-fire requirement was completely satisfactory.
The gun mounting parts, all of its mechanisms, and the vehicle’s hull and assemblies are durable during both firing and during travel. Inspection of the marked assemblies revealed no warping.
The self-propelled gun’s stability during firing is satisfactory: the backward movement is reversible in the overwhelming majority of cases, and no separation of the tracks from the ground was observed.
Misalignment of aim was insignificant, and was no more than two mils in the horizontal plane on the aiming circle. There was no misalignment in the sight settings.
The ride characteristics of the self-propelled gun were the same as for the KV-1S tank’s running gear.
Servicing of the gun, both during preparation for firing and during firing, was satisfactory.
The vehicle and gun assemblies are accessible, both during preventive maintenance and during halts while on the road.
The sights are in convenient locations.
The 152 mm self-propelled gun is well-designed. The spacious roof of the fighting compartment and the armor design make it possible to assemble the gun and the vehicle separately and install the fully assembled gun in the vehicle together with all of its components. The gun is well balanced: little effort is required to operate the laying mechanism flywheels.
The gun opening in the firing compartment is well protected at all elevation and traverse angles. The illumination in the fighting compartment and the driver’s compartment is completely satisfactory. The gun commander is provided with vision devices and both internal and external communications equipment. The SPT&A kits for both the gun and the vehicle have been developed, and the prototype equipped with a vehicle-transportable kit.
Loading ammunition into the vehicle through the hatch is convenient.
VI. Design flaws
A. Items requiring correction for the first production run
The firing and road tests revealed a need to make the following design modifications to the self-propelled gun:
1. Prevent cases from catching on the breech face when they are inserted into the bore from the loading tray.
2. Make it easier to remove ammunition stacked on the upper shelves.
3. Mount a sight in front of the driver for coarse aiming of the vehicle at targets.
4. Install a Luch-type device for illuminating the gun sight.
5. Move the traversing mechanism mount that interferes with the driver.
6. Include a manual screw-type ejector in the gun’s SPT&A kit (1 ea.) for extracting swollen cases without exiting the vehicle.
7. Add a step to facilitate entering and exiting the fighting compartment.
8. Install a barrier to protect the oil tank fittings from being damaged when removing shells from a shelf.
9. Relocate items in the artillery SPT&A kit (panoramic sight, ejectors, fuze wrenches, rammer, etc.) to place them close at hand for the crew members that need to use them in combat.
B. Items requiring additional design work
1. Better facilitate servicing of the gun during combat and increase the rate of fire. To achieve this, the Commission recommends the following approaches:
a) Extend the rear turret plates to match the maximum size of the front plates.
b) Attach the storage rack for all shells to the left rear side turret plate by lengthening the rear plates to match the front.
c) Attach the storage rack for the cases on the right side of the fighting compartment to enable assignment of the loading of cases to the breechblock operator.
d) Design the gun to have a sliding wedge breechblock.
e) Relocate the fuel and oil tanks inside the fighting compartment as a result of the change in the turret size and ammunition location.
Alter the tank sizes, abandoning the use of production items.
2. Move the traversing mechanism housing to the right in order to improve working conditions for the driver.
3. Replace the steering clutches with a planetary steering mechanism.
4. When manufacturing the KV-1S tank’s hull and turret of highhardness armor and replacing its mirrored vision blocks with the MK-4 or T-80, make the appropriate changes in the self-propelled gun drawings, as well.
5. Make all changes to the self-propelled gun drawings needed for manufacture and testing of the first self-propelled gun production run.
VII. Conclusion
1. The self-propelled gun mounting the 152 mm gun-howitzer model 1937 on a KV-1S chassis developed by designers at the Kirov Factory of the People’s Commissariat of the Tank Industry and Factories No. 172 and 9 of the People’s Commissariat of Arms, with its artillery system manufactured at Molotov Factory No. 172 and its chassis manufactured at the Kirov Factory under the People’s Commissariat of the Tank Industry, has met the requirements for this type of self-propelled artillery and has passed proving-ground tests.
2. It is hereby recommended that this self-propelled gun be placed in service with Red Army artillery and that mass production of the system begin with changes made in accordance with paragraph A of section VI of this report.
3. It is hereby recommended that the Kirov Factory of the People’s Commissariat of the Tank Industry and Factories No. 172 and 9 of the People’s Commissariat of Arms develop a draft self-propelled gun project with the changes stipulated in paragraph B of section VI of this report and present it to the Artillery Committee for review by March 15 of this year.{5}
Thus, the Red Army finally got its first mass-produced heavy SP gun. On February 9, 1943, Stalin signed State Defense Committee Decree No. 2859ss, “On a Plan for Producing Tanks, Self-Propelled Guns, and Tank Diesel Engines During February 1943.” Among the combat vehicles to be produced in February were 30 KV-14’s. That, however, was only the beginning: on February 14, Stalin signed State Defense Committee No. 2883ss, “On Production of SU-14 Self-Propelled Guns, KV-1S Tanks, and Armored Hulls for Them During February and March 1943.” That date marks the birth of the SU-152:
For purposes of implementing State Defense Committee Decree No. 2859ss, dated February 9, 1943, as regards production of SU-14 152 mm self-propelled guns in February 1943 and ensuring their production in March 1943, the State Defense Committee decrees that:
1. The People’s Commissar of the Tank Industry (Comrade Zaltsman), Kirov Factory Director Comrade Dlugach and Factory No. 200 Director Comrade Shcherbakov shall:
a) Immediately begin mass production of the SU-14 152 mm self-propelled gun and armored hulls for it in accordance with the drawing of the prototype that was provided to the State Commission on January 30, 1943, for testing, taking into account the Commission’s remarks made in the test report dated February 7 of this year.
b) Ensure the manufacture of SU-14 self-propelled guns and KV-1S tanks at the Kirov Factory in February 1943 in accordance with State Defense Committee Decree No. 2859ss of February 9, 1943, and in March 1943 in accordance with State Defense Committee Decree No. 2693ss of January 4, 1943, as partially amended in the following quantities:
| - | (number of units) | |
| February 1943 | March 1943 | |
| SU-14 SP guns | 30 | 75 |
| KV-1S tanks | 75 | 50 |
also manufacture armored hulls for the SU-14 SP guns and KV-1S tanks in February and March 1943 as follows:
| - | (number of units) | |
| February 1943 | March 1943 | |
| SU-14 armored hulls | 35 | 100 |
| KV-1S armored hulls | 75 | 40 |
2. The head of the Red Army’s Main Artillery Directorate (Comrade Yakovlev) shall, by March 20, 1943, approve the drawings and specifications for the SU-14 self-propelled gun with the flaws identified in February and March 1943 corrected for manufacture of the first batch.
3. The People’s Commissar of Arms (Comrade Ustinov), Factory No. 172 Director Comrade Bykhovsky, and Factory No. 69 Director Comrade Kotlyar shall:
a) Deliver to the Kirov Factory of the People’s Commissariat of the Tank Industry for the SU-14 self-propelled gun ML-20 guns with frame, elevation and traversing mechanisms (from Factory No. 172), and optics (from Factory No. 69) (in accordance with the delivery for the SU-14 prototype) in the following quantities:
| - | Total | From the 1st to the 10th | From the 10th to the 15th | From the 15th to the 20th | From the 20th to the 28th/31st |
|---|---|---|---|---|---|
| February | 50 | – | 5 | 15 | 30 |
| March | 75 | 25 | 12 | 13 | 25 |
b) Manufacture frames in February 1943 at Factory No. 172 of the People’s Commissariat of Arms in numbers sufficient to ensure deliveries of ML-20 guns to the Kirov Factory;
c) Send a group of 10–15 designers and riggers in February and March 1943 to the Kirov Factory to assist in the installation of the ML-20 guns.
4. In February 1943, the People’s Commissar of the Tank Industry (Comrade Zaltsman) shall produce Bessemer steel castings at Factory No. 40 of the People’s Commissariat of the Tank Industry for a preproduction batch of frames for the ML-20 gun and deliver them to Factory No. 172 by February 22, 1943.
5. The People’s Commissar of Arms (Comrade Ustinov), together with the head of the Red Army’s Main Artillery Directorate (Comrade Yakovlev), shall test the Bessemer steel frames in February 1943 and decide on their suitability for use on the ML-20 gun for the SU-14 self-propelled gun.
6. When the People’s Commissar of Arms and the head of the Red Army’s GAU come to a decision regarding the feasibility of using Bessemer steel to manufacture the ML-20 frames, the People’s Commissar of the Tank Industry (Comrade Zaltsman) shall arrange for them to be cast in March and April 1943 at Factory No. 40 of the People’s Commissariat of the Tank Industry and delivered to Factory No. 172 of the People’s Commissariat of Arms in numbers appropriate to the production program for the ML-20 guns for SU-14 artillery systems at the Kirov Factory of the People’s Commissariat of the Tank Industry.
The Bessemer steel cast frames for the ML-20 gun shall thereafter be manufactured at factories of the People’s Commissariat of Arms.
If ML-20 gun frames made of Bessemer steel cannot be used, beginning in March 1943 they shall be manufactured of special steel at factories of the People’s Commissariat of Arms.{6}
Contract No. 1489-73 for delivery of SU-14 SP guns was concluded on March 18, 1943, between the Kirov Factory of the People’s Commissariat of the Tank Industry and the GAU’s Artillery Tractor and Self-Propelled Artillery Department Tractor Directorate. Under the contract, the Kirov Factory was to deliver 30 SP guns in February and another 75 in March. Each SP gun cost 265,000 rubles. The contract was backdated because the SU-14 had already been in production for two months.
The rapid and efficient course of events from a 1:10 wooden model to mass production did not go unnoticed. On March 23, 1943, Izvestiya published the Decree of the Council of People’s Commissars of the USSR, “On the Award of Stalin Prizes for: a) Outstanding Inventions and b) Fundamental Improvements in Production Methods during 1942.” Among the winners listed in paragraph 8 were Zh. Ya. Kotin, S. N. Makhonin, L. S. Troyanov, and F. F. Petrov, who received an award for “development of a new type of artillery weapon.”
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