Forward Wing Tip Design for Induced Drag Reduction of Quad Tilt Wing VTOL Un-Manned Plane in Cruise

摘要

We study about quad tilt wing VTOL plane as S/VTOL plane technics in Aeronautical Directorate, Japan Aerospace Exploration Agency (JAXA). Flight feasibility of this type plane has been confirmed in past study. One of the problems for practical use is to improve cruising efficiency to obtain long distance and longtime flight performance. From this point of view, we are studying about improvement of aerodynamic performance in cruise. This type plane has tandem wing. Backward wing of tandem wing is strongly affected by the wake of forward wing. We suggested backward wing interference model by forward wing as wing in steady flow deflection angle distributions using lifting line theory and derived backward wing lift distribution to minimize its induced drag. This model shows upwash span region where forward wing wake is upwash can reduce its induced drag. So we suggest new forward wing tip design concept to extend upwash span region at backward wing to reduce induced drag of backward wing. Aerodynamic characteristics of backward wing can be simply estimated by previous model. We designed forward wing tip which realize this concept and confirmed this wing tip can reduce backward wing induced drag although forward wing induced drag doesn't increase.