Performance Assessment of a Flapping Wing Ornithopter through Load Cell Integration using Wind Tunnel Experimentation

Abstract

Wings of the birds are examined to comprehend these natural flyers with flapping wings and its ability to provide enough lift to fly. Semi-elliptical wing planform reduces the induced drag when the span wise distribution of the lift is elliptical. Hence, the objective of this study is to investigate the flapping wing ornithopter to quantify the lift, drag and pitching moment coefficients using load cell technology using low-speed wind tunnel experimentation. The aerodynamic performance of a flapping-wing ornithopter at various angles of attack (±15°) and throttle settings (viz., 0% to full throttle) with wind velocity varying from 5m/s to 15m/s are studied. At 0° angles of attack, the lift coefficient varies from -0.741 to 1.707 indicating a varying lift generation efficiency, while the drag coefficients range from 0.047 to 0.099 reflecting different aerodynamic drag characteristics. A consistent trend is observed in the pitching moment coefficients, lift coefficients and drag coefficients across different angle of attacks at 20%, 40%, 60%, 80% and full throttle. The flexibility of the wing creates a passive pitching action that improves the aerodynamic performance of the ornithopter.