Who invented the helicopter rotor system and when?

The helicopter rotor system, which makes vertical flight possible, was developed by Igor Sikorsky, a Russian-American aviation pioneer. Sikorsky’s VS-300, built in 1939, was the first practical helicopter that incorporated a functional rotor system, allowing for controlled, sustained flight. His design included a single main rotor and a tail rotor, providing stability and control during flight. Sikorsky’s successful design marked the beginning of the modern helicopter, which became crucial in military, medical, and civilian aviation.