Experimental Investigation of Aerodynamic Performance of a Novel Multirotor Tandem Wing Convertiplane UAV During Forward Flight and Transition

This paper discusses the preliminary results from the experimental study of the aerodynamic performance of a novel multirotor tandem wing Unmanned Aerial Vehicle (UAV) during forward flight and transition to quantify the wing-wing and propeller-propeller interactions. The horizontal and vertical separations between the tandem wings are key design parameters for the current convertiplane configuration and are systematically identified through experiments performed in NWTF wind tunnel at Indian Institute of Technology Kanpur. For this a "half model" of the actual UAV wing is fabricated using 3D printing and tested at different wind speeds and angles-of-attack. For the baseline horizontal separation of 50% of wingspan and no vertical separation the ideal combination of wing setting angle is identified to be 3° for fore wing and 6° for the aft wing, as this combination offsets the downwash effect of fore wing on the aft wing with increased angle-of-attack and also takes advantage of the upwash of the aft wing to enhance the lift on the fore wing. A horizontal spacing equal to at least 50% of span is observed to give good performance for both the fore and aft wings. The vertical separation enhances the lift on the aft wing significantly. A vertical spacing of 30% of the wingspan helps minimize the interference between the wings and the propellers.