Sikorsky S-75

The Sikorsky S-75 was a proof-of-concept all-composite helicopter built under the United States Army Advanced Composite Airframe Program, whose goal was a lighter and cheaper airframe than the metal ones then in use, in support of the Light Helicopter Experimental program. Contracts went to Sikorsky and Bell in February 1981. The S-75 joined an entirely new composite airframe, mostly Kevlar and graphite, to the twin turboshaft engines, transmission and rotors of the civil S-76A, and carried two pilots and up to six passengers. It first flew on 27 July 1984, passed a 50-hour Army evaluation that beat the weight and cost targets, and was put into long-term storage after testing ended in April 1985.