Leading- and trailing-edge effects on the aeromechanics of membrane aerofoils

This study explores the effect that geometry of silver steel supports have on the aeromechanic performance of membrane aerofoils. Tests are performed at low Reynolds numbers, Re= 9 x 10(4), and incidences of 2 degrees-25 degrees High-speed photogrammetry as well as force measurements are carried out to explore the effects of four different leading-edge (LE) and trailing-edge (TE) designs on the performance of membrane aerofoils. Results indicate that the mean camber as well as membrane vibrations (both mode shape and frequency) change with geometry and size of the LE and TE supports. The LE/TE supports with a rectangular cross-section consistently provide higher lift forces and higher mean camber deformations compared to the support with circular cross-section. The membrane vibrations are also found to be higher for aerofoils with LE/TE supports with rectangular cross-section. Moreover, it is shown that the LE/TE supports deflect under aerodynamic loading and consequently alter the performance of the aerofoil. Furthermore, some of the supports are found to vibrate at their resonance frequency. In all, this study quantifies the impact of the leading- and trailing-edge support on the membrane and provides guidelines for geometry selection for future studies. (C) 2013 Elsevier Ltd. All rights reserved.