Experimental Investigation of the Pressure, Force, and Torque Characteristics of a Rigid Flapping Wing

Pressure measurements over flapping wings are less commonly available due to the difficulties associated with instrumenting them. This represents an important limitation of the aerodynamic data available for the development of self-contained flapping wing vehicle autopilots and for researchers working on the aerodynamics of bio-inspired flapping wings. This paper describes the design, construction, and testing of a customized flap stand, and a distributed pressure sensing system embedded in a set of rigid flapping wings to provide high speed ‘on-board’ flow measurements. While the hovering condition is the main focus, the setup is applicable to forward flight conditions as well. Data processing techniques are described along with the method used to measure pressure distributions over the wings. A series of flap tests were conducted in still air, with pressures measured only in air and force and torque measurements taken both in air and in a vacuum. Comparisons between the pressure-based estimates of aerodynamic loads and direct measurements taken by the force instrumentation are presented. The comparisons suggest the pressure-based system provides reasonable estimates of aerodynamic loads but is limited by the frequency response of the pressure lines used.