Low-noise flapping wings with tensed membrane

Micro air vehicles with flapping wings have the potential to be both more efficient and maneuverable than similarsized fixed-or rotary-wing aircraft. Reducing the perceived noise produced by flapping wings without compromising or possibly enhancing their aerodynamic performance would be crucial in surveillance and military applications. To this aim, flapping wings have been designed and fabricated for which the supporting stiffeners tense the Mylar membrane to which they are bonded. The sound produced by these wings at different flapping frequencies has been recorded in an anechoic chamber simultaneously to the upward thrust they create. Comparing their characteristics and performance with those of flapping wings of conventional design suggests that tensing the wing’s membrane can increase the thrust while decreasing the typical rustling noise of the flapping wings.