Comparing: SU-14-1 vs. S-51

Developed on the basis of the SU-14. In 1936 a prototype was manufactured and tested. In 1937 the project supervisor was purged and the project was canceled. The prototype was shipped to Kubinka for storage. In 1941, during the Battle of Moscow, the SU-14-1 was used for long-range bombardment.

Developed by the Grabin Central Artillery Design Bureau in the fall of 1943. The S-51 passed trials successfully in the spring of 1944, but never entered mass production.