Sikorsky S-75 Sikorsky S-75 The Sikorsky S-75 was a proof-of-concept all-composite helicopter. Sikorsky Aircraft used all-composite materials to replace metal to provide greater strength, lighter weight, lower manufacturing costs, and reduce maintenance costs. The Sikorsky S-75 was developed under the US Army's Advanced Composite Airframe Program (ACAP), the goal of which was the development of an all-composite helicopter fuselage, lighter and less costly to build than predominantly metal airframes in support of the Light Helicopter Experimental (LHX) program. In February 1981, contracts were awarded to Sikorsky and Bell Helicopter, with Bell submitting its Model D292. The S-75 flew for the first time
Sikorsky S-3 Sikorsky S-3 The Sikorsky S-3 was an early Russian single seat biplane design by Igor Sikorsky. Work on the machine started in July 1910 and was completed in late November. The S-3 was a larger improved version of the S-2 with a more powerful Anzani three-cylinder engine. The main wings were manufactured in a more uniform manner with the ribs held to a closer tolerance and the fabric covering was of better quality. Other refinements included larger ailerons and faster responding flight control surfaces. The S-3 exhibited performance superior to the S-2 and Sikorsky made a dozen successful flights starting