Experimental analysis of a blown-wing configuration during transition flight

Abstract : Transition flight phase between near-hover state and high-speed cruise for a convertible aircraft was characterised by unusual attitude and large airspeed variations, which lead to large uncertainty in predicting vehicle flight dynamic characteristics. Under the context of new unmanned aerial system development, more accurate estimation of longitudinal aerodynamic performance in transition phase needs further study. This research focused on an experimental study of a blown-wing configuration at high angle of attack and low airspeed conditions, typical for transition phase. A separately mounted tractor propeller module was placed in the low Reynolds number wind tunnel SaBRe at ISAE-SUPAERO, in order to easily modify its position and orientation. A high-aspect-ratio wing was equipped with near full-span flap as pitch flight control. Test conditions were carefully chosen to represent transition phase with angle of attack ranging from 0° up to 90° at different airspeeds. Results were obtained and analysed for lift and pitch moment to further understand propeller wake effect on the augmentation of aerodynamic loads.