Abstract: A rotor blade measurement system includes a microwave source and a probe. A directional coupler is attached to the source and the probe. A detector is attached to the directional coupler. The probe directs a microwave signal toward a rotor such that during rotation the rotor blade will pass through the path of the microwave signal. As the rotor blade passes the microwave signal is reflected back to the probe. The directional coupler separates the original microwave signal and the reflected signal. The detector then determines the energy level of the reflected signal. As each rotor blade passes the microwave signal it generates a reflected signal that can be analyzed over time. From the length and shape of the waveform of the reflected signal the amount of twisting and flutter in a rotor blade can be determined.

Abstract: A Rotary Air-data System (RADS) periodically samples pressure data from a main rotor blade mounted pitot-scoop integrated with a high accuracy pressure sensor to compute a velocity vector that is resolvable into the aircraft's coordinate system. Mathematical techniques are employed which provide accurate computations of static pressure without a static pressure sensor. The RADS also computes the direction of the relative wind which is particularly useful when the pilot executes hover or low speed, low altitude maneuvers in restricted visibility. The availability of relative wind velocity information coupled with navigation data enhances the ability of rotary aircraft to perform accurate low altitude hover, fire control and other autopilot maneuvers.