Experimental investigation of a flapping wing concept in hover and forward flight for micro air vehicle applications Conference Paper uri icon


  • The paper describes the systematic experimental studies that have been performed to understand the role of the two key degrees of freedom, flapping and pitching, in the aerodynamic performance of a flapping wing, in both hover and forward flight. The required flapping kinematics was prescribed mechanically using a four-bar mechanism and the wing dynamic pitching/twisting was obtained in a passive fashion by utilizing the inertial and aerodynamic forces acting on the wing. The forces produced by the wing were measured at the wing root using a six-component balance at different flapping frequencies, flapping/pitching amplitudes and wind speeds. The results clearly showed that the maximum thrust in hover can be achieved by using symmetric, high amplitude passive pitching. However, in forward flight, the optimum aerodynamic performance (lift and propulsive thrust) was obtained using asymmetric wing pitching at low pitching amplitudes. It was also observed that dynamic twisting (obtained using flexible wings), instead of dynamic pitching, produced better performance in forward flight because dynamic twisting caused both spanwise and temporal modulation of wing pitch angle, which is important since flapping produces both spanwise and temporal variation of angle of attack. Pure flapping (no pitching) of rigid wings in forward velocity at high reduced frequencies and high pitch angles produced three-fold increase in lift coefficient over static values. However, pure flapping only produced positive propulsive thrust at extremely low pitch angles. The maximum thrust in the presence of forward speed was obtained using symmetric pitching. To study the aerodynamics in detail, an unsteady aerodynamic analysis based on strip theory was implemented and the normal force predictions from the analysis were validated with test data. 2010 by the American Helicopter Society International, Inc.

published proceedings

  • Annual Forum Proceedings - AHS International

author list (cited authors)

  • Malhan, R., Benedict, M., & Chopra, I.

complete list of authors

  • Malhan, R||Benedict, M||Chopra, I

publication date

  • December 2010