Wind-Tunnel Tests of a 10-Foot-Diameter Gyroplane Rotor

This paper presents the results of wind-tunnel tests on a model gyroplane rotor 10 feet in diameter. The rotor blades had zero sweepback and zero offset; the hub contained a feathering mechanism that provided control of the rotor rolling moment, but not of the pitching moment. The rotor was tested with 4 blades and with 2 blades. The entire useful range of pitch settings and tip-speed ratios was investigated including the phase of operation in which the rotor turned very slowly, or idled.

The results afford valuable information concerning the influences of pitch setting, solidity, and feathering angle upon the rotor characteristics. The feathering control appeared to be satisfactory in the normal flying range but showed a marked decrease in effectiveness at very low tip-speed ratios. A feathering angle considerably greater than the 10° that was provided was required at high tip-speed ratios and high pitch settings to obtain zero rolling moment. Unfortunately, because the rotor hub was disproportionately large, the measured lift-drag ratios are considered to be inexact.