Friction-Sensing Reflector Array Patches (FRAP)

Research Support Instruments, Inc. (RSI) proposes to develop the Friction-Sensing Reflector Array Patches (FRAP), a technology that will measure the shear stress distribution on aerodynamic surfaces in ground test facilities with high resolution, sensitivity, and bandwidth. Unlike the oil-film interference method, FRAP patches will not be thinned as a function of time during a test. No knowledge of the streamlines of the flow will be needed in order to calculate the local stress distribution; this will avoid the tracers needed with the oil-film interference approach. Flexible patches of FRAP arrays, inexpensive due to simple, mass-production-compatible microfabrication techniques, will be interrogated using a light source and camera. FRAP will be independent of the flow species and applied as a very thin, flexible, adhesive material. The Phase II goals will be to improve the design and fabrication of the sensors, fully calibrate taking into account competing effects such as normal forces and temperature, demonstrate feasibility in a wide range of test environments from subsonic to heated and cold supersonic, and provide prototype units to NASA. The result will be a product that will address a critical NASA instrumentation need.