Sikorsky S-73
The Sikorsky S-73 was a proposed aircraft design to meet the United States Army requirement in 1970 for a Heavy Lift Helicopter (HLH) capable of carrying 45,000 lb (20,000 kg; 20 t), 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 with a simplified and improved single main rotor powered by three General Electric TF34-58 turboshaft engines rated at a combined 21,000 hp (15,660 kW).