Sikorsky R-6 Doman Conversion (LZ-1A)
Gift of Frank J. Pacheco
Designed and developed by Sikorsky Aircraft and converted to this configuration by Doman Helicopters, this U.S. Army Air Force R-6A is one of about 200 produced by Nash-Kelvinator just before the end of World War II.
This hingeless rotor design that was developed is driven by a constant-velocity universal joint making it free to tilt relative to the fuselage without causing any stress or vibratory effects. The blades, increased in diameter by two feet from the standard R-6, are so well balanced that fingertip control forces were enjoyed without any servos. The hingeless rotor concept was adopted by many designers some 40 years later.