The Sikorsky S-73 /ref> was a proposed aircraft design to meet the
United States Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
requirement in 1970 for a Heavy Lift Helicopter (HLH) capable of carrying , a lifting capacity more than twice that of Sikorsky's most powerful helicopter at that time.
The Sikorsky's S-73 design was an enlarged version of the successful CH-54/
S-64
The Sikorsky S-64 Skycrane is an American twin-engine heavy-lift helicopter. It is the civil version of the United States Army's CH-54 Tarhe. It is currently produced as the S-64 Aircrane by Erickson Inc.
Development Under Sikorsky
Th ...
with a simplified and improved single main rotor powered by three General Electric TF34-58 turboshaft engines rated at a combined . A crew of five would operate the aircraft from the forward cockpit with pushbuttons replacing the traditional
cyclic stick
A helicopter pilot manipulates the helicopter flight controls to achieve and maintain controlled aerodynamic flight. Changes to the aircraft flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor bla ...
and collective lever. Behind the cockpit an aft cabin provided capacity for 12 combat troops.
Sikorsky submitted their design in February 1971, then in May the Army declared the
Boeing Vertol XCH-62
The Boeing Vertol XCH-62 (Model 301) was a triple-turbine, heavy-lift helicopter project designed for the United States Army by Boeing Vertol. Approved in 1971, one prototype reached 95% completion before it was canceled in 1975. The prototype wa ...
winner of the contract, ending the Sikorsky S-73 program.