CHAPTER 7.
The Monster from Chelyabinsk
The startup of SU-14 production at the Chelyabinsk Kirov Factory resulted in no unexpected problems. Unlike the SU-35 (SU-122) and the SU-12 (SU-76), the Chelyabinsk machine began production in a form virtually unchanged from that of the prototype. That was largely due to the fact that the KV-1S chassis was almost unchanged, and the same thing was true of the gun system. In addition, the designers had good ideas from the very beginning, and that kept the rework to a minimum.
However, it would be incorrect to say that the SP gun had no problems. The test commission had pointed out some of the KV-14’s shortcomings in its finding. The Kirov Factory sent similar reports to Eng. Col. Kovalev, chief of the 6th Department of the GABTU’s Tank Directorate:
Some shortcomings of the fighting compartment:
1. The loading tray for the shells and cases needs to be raised slightly because it is difficult to feed cases into the barrel.
2. The additional tray on the loader’s side needs to be hinged so that it can be raised, because it interferes with the loader.
3. When the gun is traversed to the right or left, the position of the gunner or the breechblock operator, respectively, becomes tight.
4. At the extreme positions of the barrel, it becomes difficult to operate the traversing mechanism flywheel, and it interferes with the fuel tank.
5. The ammunition rack is in a bad position; it is difficult to use.
6. The gap between the gun tube and the mantlet is too large; bullets can enter.{1}
Some of these shortcomings required design changes that were too extensive, and they were not corrected before production began. Launching production of the KV-14 was a high priority task, so even the most important fixes were postponed to a later date. Moreover, even the development of technical documentation for approval by the GAU, which the factories were supposed to submit by March 20, 1943, was delayed. Repeated appeals by GAU representatives to the factory directors and People’s Commissar of the Tank Industry Zaltsman were to no avail. Only a complaint to Molotov on April 12 produced results; the documentation was finally submitted five days later. The factories had put the plan B modernization program (expansion of the fighting compartment, an ML-20 with a sliding wedge breechblock, etc.) out of their minds as though it were a bad dream. Moreover, the first sketches of the ML-20 on the IS chassis (the future ISU-152) frankly show that the designers became aware of the fighting compartment expansion only in the fall of 1943.
Despite the fact that mass production of the SP gun generally began relatively smoothly, there were problems with some components. The gun system frames delivered for assembly frequently had size defects, requiring them to be adapted to fit in the mantlet, and that took additional time. Also, mishaps often occurred with deliveries of the gun SPT&A kits that accompanied the ML-20S systems from Factory No. 172.
There were also some mishaps in the beginning with the optics. As mentioned earlier, the T-10 telescopic sights were not being manufactured when the SP gun went into production, so the first TV-14’s were equipped with T-9 sights from the KV-2. According to the plans, the first 20 T-9s were expected by February 20, 1943, and another 105 by March 5. The problem was that the T-9 still had the scales for the M-10T tank howitzer, whose ballistics were very different from those of the ML-20. There was also confusion about names: Factory No. 69 produced the 10T tank sight in addition to the T-10 sight, which had an elbow, and that meant there was a risk of a mixup occurring in deliveries to the factories. To avoid that, the T-10 sight was renamed the ST-10 (for “self-propelled telescopic”).
It should be noted that the T-9 sight had been chosen out of necessity. According to correspondence with Factory No. 69, it was selected because it was the only suitable sight in production at the time. To simplify production, in June 1943 Factory No. 69 developed a sight with a similar name that was based on the ST-10 but had no elbow. The effort was led by Factory No. 69’s lead designer, Finkelstein, one of the engineers who had worked on the TMFD-7 and TMFP-1 sights. On June 15, 1943, Factory No. 69’s chief engineer, Skarzhinsky, sent a letter to the People’s Commissariat of Arms in which he proposed replacing the ST-10 with the promising new sight.
The ST-10 sight (formerly the KT-1) is currently being used for the self-propelled gun.
The ST-10 sight was selected only because it was the sole available sight with the right characteristics and right length for the purpose.
However, we could suggest a simpler, better designed, and better quality sight that would be less difficult to manufacture. Indeed, the sight’s elbow, which contains two prisms and an erector lens, adds unnecessary parts that, regardless of their reliability, can cause problems with the sight’s alignment and operation. They also reduce image quality because the system cannot be properly centered no matter how carefully they are assembled and aligned, especially since one of the prisms is not located in a parallel light beam. Also, manufacture of the elbow requires the expenditure of manpower, machinery, and nonferrous metals and other scarce materials that could better be used for other purposes.
We have developed a new sight (that has no elbow) based on the ST-10. Its length can be modified to meet your requirements, and it is more reliable, of better quality, and simpler than the existing sights.
Enclosed herewith is a dimensional drawing of the sight. I request that you instruct the Kirov Factory to develop a new mount for it and relocate the opening in the mantlet as appropriate. The factory can begin producing these sights immediately upon receipt of your consent.{2}
The People’s Commissariat of Arms and the Main Artillery Directorate took an interest in Factory No. 69’s idea, and a proposal to pursue development was sent to GABTU’s Self-Propelled Artillery Office (USA GABTU). That, however, is where the history of the simplified version of the ST-10 ends. The Kirov Factory was completely unable to modify the mantlet and sight mounts at that time. Thus, the temporary solution in the form of the ST-10 became permanent. Moreover, the ISU-152 and ISU-122 SP guns that came later employed the same sight.