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Multi-motored Airplanes, 1933


Returning to Russia with plans and a 25-horse power engine, Sikorsky built a helicopter which met all dynamic and control principles yet failed the crucial test: it could not lift off the ground. The weight of the required engine driving power overcame its lifting power. The helicopter project was cancelled, all useful data was recorded, and attention moved to fixed wing aircraft. The data was useful many years later when lightweight engines became available and Sikorsky returned to his first enthusiasm of building helicopters.

Allen Postcard
Postcard from Henry B. Allen, Accepting chairmanship
of the CSA sub-committee on Application No. 2942, 5/23/1931 (770K)