Keldysh bomber
The Keldysh bomber was a Soviet design for a rocket-powered sub-orbital bomber spaceplane, which drew heavily upon work carried out by Eugen Sänger and Irene Bredt for the German Silbervogel project. Development. During the closing weeks of World War II, the German work at Peenemünde was investigated by Soviet intelligence, amongst whom was rocket motor constructor Alexey Isayev, who found a copy of Sänger and Bredt's report. A translation was soon circulating among Soviet rocket designers, and a condensed version made its way to Stalin himself. In November 1946 the NII-1 NKAP research institute was  formed with mathematician Mstislav Vsevolodovich Keldysh as its head to investigate and develop the German Sänger–Bredt design. In 1947, studies indicated that the high fuel consumption of Sänger's rocket-based design rendered the concept impracticable in the short term. Using engines considered to be available in a reasonable timespan, 95% of the vehicle's initial mass would have to be propellant. However, use of ramjets during the acceleration phase would give the craft a more reasonable 22% dead weight and still achieve the 5 km/s velocity required for a intercontinental range. It was estimated that it would  take until the mid-1950s before a draft project of a feasible design could be prepared, and by that time the design had been made obsolete by more advanced designs. However, the work carried out would lead to the EKR, MKR, Buran, and Burya ramjet cruise missiles.