The Silbervogel rocket plane concept developed in Germany during World War 2 is fairly well known. What is less well known is that the Soviets briefly continued development of the concept after the war.
The Keldysh Bomber had several similarities to the Sanger design it was developed from. Like the German design, it would have been ground launched at high speed from a fixed track using a rocket sled (although it would have kerolox engines instead of alcholol/LOX V2 engines). The main difference was in the boost stage. Soviet engineers correctly realized that a pure rocket design would need a ridiculously high mass ratio to achieve near orbital velocities in a single stage with the rockets of the day. They reasoned that by using ramjets, they could harvest oxidizer from the atmosphere at low altitudes, reducing the amount of fuel needed. The ramjets would take the bomber to an altitude of about 20 kilometers at about Mach 3, at which point they would shut off. The onboard rocket would continue burning, and provide the remainder of the velocity needed (about 5 km/s). Payload was similar to the Silbervogel, about 8,000 kilograms. A payload of about 8,000 kilos would be disappointing in terms of conventional explosives, but it would be enough to carry a first generation nuclear weapon.
Obviously, the Keldysh bomber did not progress past the design stage. The engineering challenges were simply too great; ramjet and rocket technology was still in its infancy. Additionally, like the Silbervogel, thermal loading on reentry/skip would have been a severe issue. It is likely that the Keldysh bomber would note have been ready until the late 1950s, at which point the R-7 and other ICBMs would make it obsolete. However, the Soviets did develop many high altitude / high speed cruise missiles during the 1950s, such as the Lavochkin Burya (comparable to the American Navajo). Also, the Keldysh bomber does bear at least a superficial resemblance to the British Skylon design of the 21st century (though the concepts behind them are far different).