By the time the Korean War ended in 1953, helicopters such as the Piasecki H-25 and the Sikorsky H-19 Chickasaw had become a staple of the United States Air Force. But getting there wasn't achieved without its difficulties.
To overcome some of the operational challenges brought on by perilous mountains and unpredictable weather, the Bureau of Aeronautics, Sikorsky Aircraft, Reaction Motors, and the Marine Corps developed the Rocket On Rotor power plant.
The auxiliary power boost system, which could be activated with a switch installed in the cockpit, employed rocket engines mounted on rotor blade tips.
If successful, this innovative device would render American helicopters capable of performing maneuvers no other aircraft could.