Publication

Abstract : A flapping wing MAV (FMAV) named KAVAS was made in which the potential energy stored in a rubber band was converted to kinetic energy (mechanical) using a simple 4-bar mechanism. Rubber bands of three kinds - conventional, light weight elastic and heavy were used along with along with ice cream sticks, balsa wood, mild steel wire, beads, carbon fiber and tissue paper for fabrication. A parametric study on flapping mechanism gave the relationship between the flapping frequency and the frequency provided by the rubber band to the crank. The flapping frequency of the wing during flight was measured to be 6.15Hz. It was estimated that 25% of the rubber band energy was used and that the forward velocity of the model was experimentally found to be 2.8m/s. The figure of 8 trajectory followed by the wingtip was revealed, demonstrating the flexibility of the wing. The aerodynamic parameters of the final model were evaluated using the DeLaurier’s strip theory with a modification to account for the relatively high maximum flap angle of greater than 20 degrees. It was theoretically predicted that the dynamic twist should be 3 degrees/cm and the angle between flapping axis and the free stream should be 9 degrees to produce the required thrust and lift. Based on this, instantaneous lift and thrust over a cycle were plotted. Effects of using different wing and tail material were also studied.