A Model-Scale Wind-Tunnel Study of Main Rotor/Propeller Interference

A model-scale wind tunnel test was conducted to determine propulsive efficiency and relative vibration levels of a tail mounted propeller in the wake of a powered rotor and generic fuselage. Six-component propeller loads were measured for all test points with a focus on thrust and torque. Propeller and main rotor operating conditions were set to mimic low- and highspeed vehicle flight operations, simulating speeds from 105 kts to 200 kts. A total pressure wake survey conducted without the propeller installed was used to determine the propeller plane inflow characteristics. Propeller operation had no measureable effect on rotor trim whereas the main rotor states significantly altered the propeller performance. All propeller positions showed a propulsive efficiency increase relative to the isolated propeller data when operated in the rotor wake. No position showed noticeable vibration levels higher or lower than another. The highest propulsive efficiency was measured for the mid-height propeller position.