Aerodynamics and Lifting Performance of a Quad Tilt Rotor In Ground Effect

摘要

Surface pressure measurements and tuft flow visualization were used to investigate the physical mechanisms causing changes in the lifting performance of a 0.03-scale model of a QTR operating in hover and low speed forward flight near the ground. Upload on the airframe in ground effect was found to be caused by a high pressure region formed under the fuselage resulting from the interaction of the wakes from the four rotors. A ground vortex, which was convected underneath the vehicle, was found to cause changes in airframe loads at certain flight conditions. Effect of yaw/crosswind on the airframe loads of a model QTR in and out of ground effect were also studied. Increase in yaw angle resulted in an increase in download or a reduction in upload, both in and out of ground effect, especially at higher rotor wake skew angles. Operation in simulated crosswind conditions was found to increase the download on the vehicle out of ground effect and to decrese the upload in ground effect, especially at low forward speeds.