The Vought-Sikorsky VS-300 (aka the S-46) is a historically sginificant single-engine experimental helicopter.
The VS-300 is widely accepted as the first viable American helicopter design. It’s also the first in the world to use a single engine. The previous successul single-lifting rotor prototype, the TsAGI-1EA, made use of two engines and was of Russian origin.
The VS-300 made a tethered flight in 1938 and a free flight in 1939. The VS-300 pioneered the single anti-torque tail rotor design we all know today. The TsAGI-1EA in contrast had double-sided anti-torque rotors on both the nose and tail.
The prototype intially had a 75 horsepower (56 kilowatt) engine, but later a 90 horsepower (67 kilowatt) Franklin 4AC-199-E engine was used. The final VS-300 power plant was a 150 horsepower (112 kilowatt) Franklin engine.
The airframe of the VS-300 consisted of a tubular welded framework. The cyclic control system of the VS-300 was initially similar to modern helicopter design, but Sikorsky found that it didn’t perform well. The cyclic of the main rotor was then locked and two small side-mounted auxilliary rotors were installed on the tail boom to handle that aspect of movement. As the problem of main-rotor cyclic control was solved, these small rotors were later removed.
Given its status as an early helicopter, the performance of the VS-300 is impressive. It could fly at 80 kilometers per hour, cover 121 kilometers of terrain and endure 90 minutes of flight. It truly was a practical aircraft and was even viable for cargo movement.
The VS-300 is also notable for being the first practical amphibious helicopter, after Sikorsky equipped it with float pontoons and successfully landed and took of from a water surface in 1941.
The prototype was retired in 1943 and to this day remains in the Henry Ford Museum in Dearborn Michigan.