Ryan Disc Rotor System

The second high speed rotary concept is known as the Disc Rotor system. Disc Rotor system illustrated in artist's concept combines capabilities of helicopter with fixed-wing aircraft. This system utilizes a more conventional articulated three blade rotor arrangement but is equipped with a thin discus-shaped centerbody into which the blades are retracted during highspeed modes.

The thin centerbody housing the rotor blades shields them from the ambient airstream during rotor stoppage. The mechanics of retraction and extension cycles, as proposed in this concept, are accomplished by pivotal motion, thereby minimizing lost motion and increasing accuracy of rotor system C.G. control in a simple and straightforward manner.

In common with most stopped-rotor systems, the Disc Rotor concept utilizes an auxiliary wing for off-loading the rotor. Wing lift is augmented by the lift provided by the centerbody, particularly during stopped-rotor, maneuvering flight.

Aerodynamic drag penalties due to the discus centerbody are small as centerbody thickness ratios of less than 9 per cent and disc size of only 15 per cent of the basic rotor reference area are readily attainable in this system. Other significant advantages offered by the Disc Rotor system are its simplicity, the straightforward functions involved in rotor-stoppage in flight, the compatibility with conventional airframes and its low structural weight penalty.

One of the most apparent advances is the bypass of dynamic problems encountered in stopping long, flexible rotor blades while in flight.

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