Sikorsky, a Russian aeronautics engineer and inventor, was known for the first working helicopter.
On September 14th, 1939 Sikorsky flew his design of a single-rotor helicopter after he changed the angle of the lifting rotor blades as they revolve, enabling the helicopter to become airborne.
Today, his name is well known with the successful development of the versatile helicopter, which has played a vital role in the development of aviation. Sikorsky helicopters are used by all five branches of the US armed forces.
One of their best known helicopters is the Black Hawk helicopter operated by the US Army. There are about 4,000 Black Hawks flying today.