Experimental Investigation of Performance of a Wing-Propeller System for a Quad-Rotor-Biplane Micro Air Vehicle

Hover and forward flight capability can be combined in hybrid air vehicle designs such as a quad rotor biplane which is investigated in this paper. The vehicle weighs 240 grams and consists of four propellers with wings arranged in biplane configuration. To measure aerodynamic performance of the vehicle to maintain equilibrium during transition, a wingpropeller system that represents one quarter of the vehicle was used. Wind tunnel tests were performed on a single 6 in, two bladed propeller attached to a wing surface with an aspect ratio of 2.75. Tests were performed first on an isolated propeller at various shaft angles, RPM and forward flight velocity. The combined wing-propeller system was then tested to study key differences in force production with and without the wing surface. Finally trim analysis based on force measurements was performed to extract operating conditions for trimmed flight at flight modes including transition from hover to forward flight. Due to the effect of the wing on propeller slipstream and vice versa, the vertical force was greater, and the horizontal force was lower than that produced by the isolated propeller. A maximum speed of 11 m/s at 0 deg shaft angle was obtained with a cruise speed of about 6 m/s with a lift requirement of 0.6 N. The cruise power was 1.5 W which was one-third of hover power. Free flight testing successfully showed feasibility of vehicle to achieve equilibrium transition flight.