Abstract:
The objective of this investigation was to study how membrane scalloping affects the aerodynamic performance of flat, membrane wings at low Reynolds numbers. The onset of membrane vibration was also studied to determine its effects on the aerodynamic performance. This study was performed to improve the efficiency of MAVs (micro air vehicles). The removal of some of the membrane at the trailing edge of the airfoil, which has the highest amplitude of vibration, could significantly decrease the drag without overly affecting the lift. The plates studied were all flat plates with moderate aspect ratio and a repeating cell structure of latex membranes. This allowed the effects of the membrane to be studied with minimal effects from the tip vortices as long as the data was acquired behind the center cell. The onset of membrane vibration was studied using hot-wire anemometry, and the amplitude and frequency of membrane vibration were measured directly using a laser vibrometer. Through a momentum deficit analysis, local drag coefficients were obtained. These results were compared to direct measurements of lift and drag from external balance testing to determine the aerodynamic efficiency. Results showed that the shape of the latex cell has a greater impact on lift than the amount of scalloping and that the amount of scalloping has a greater affect on drag than the cell shape. These effects could allow batten-reinforced membrane wings for MAVs to be more efficient with proper membrane scalloping.
