Transport & space · 1939
Practical helicopter
Sikorsky's single main rotor and tail rotor layout makes vertical flight practical.
Igor Sikorsky's VS-300 first flew in September 1939, establishing the main-plus-tail-rotor design used by most helicopters today. The derived R-4 became the first mass-produced helicopter in 1942. Helicopters enabled air rescue, medevac and offshore oil work.