Tilt rotor aeromechanics phenomena in low speed flight

Abstract

This work investigates important aeromechanics phenomena affecting the V-22 tilt rotor in low speed sideward flight or while hovering in quartering or crosswind conditions. These phenomena, such as pitch-up with sideslip and increased power required in sideward flight, were identified during V-22 critical azimuth flight testing and impacted handling qualities in this flight regime. High fidelity, dynamic, unsteady, Navier-Stokes computational fluid dynamics (CFD) calculations are presented and compared with flight test data. CFD predicts the flight test trends as a function of wind direction, in good agreement with data. Detailed investigation clearly shows the interaction of the rotor wake with the airframe as the major cause of the aeromechanics phenomena seen on the V-22. Identification of the underlying flowfield physics allows investigation of options for alleviation and prediction of future tilt rotor configurations.