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
Igor Sikorsky 1912. In early 1912, Igor Sikorsky became Chief Engineer of the aircraft division for the Russian Baltic Railroad Car Works ("Russko-Baltiisky Vagonny Zavod" or "R-BVZ") in Saint Petersburg. His work at R-BVZ included the construction of the first four-engine aircraft, the S-21 "Russky Vityaz", which he initially called "Le Grand" when fitted with just two engines, then as the "Bolshoi Baltisky" (The Great Baltic) when fitted with four engines for the first time, each wing panel's pair of powerplants in a "push-pull" tandem configuration previous to the four tractor-engined "Russki Vityaz". He also served as the test pilot for its