Investigations of the aerodynamic performance and noise characteristics of a Dowty Rotol R212 propeller at full-scale in the 24 ft wind tunnel

Propeller power absorption and thrust have been measured over a range of rotational speeds up to 1400 rev/min at mainstream airspeeds up to 48 m/s for a wide range of blade setting. In addition, cruise conditions have been simulated by maintaining the appropriate ratio of propeller tip speed to the airspeed. Generally good agreement is shown between these full scale experiments with results obtained at 1/5 scale though the effect of Mach number is observable when the propeller is highly loaded. Noise analysis demonstrates the predominance of multiple tones whose number and intensity increase with helical-tip Mach number. An empirical formula shows that the fundamental tone varies with tip speed and power loading in a similar manner to that observed on a 1/5 scale model.