Flight Evaluation Elliott Low-Airspeed System

Abstract

Airspeed calibration tests were conducted on an experimental model of the Elliott low-airspeed system to determine its suitability for use as a helicopter airspeed instrument. The airspeed system was mounted in various locations on the UH-IC helicopter., Emphasis was placed on the low-speed flight regimes where the sensor operated in rotor downwash. Testing was performed by the US Army Aviation Systems Test Acitvity at Edwards Air Force Base, California, between 21 June and 15 November 1971. The evaluation required 13.7 productive test flight hours. The system provides reliable, accurate airspeed data from hover to 120 knots in the direction for which the sensor is mounted, and results indicate an omnidirectional system is feasible. The system is simple, is highly reliable, should be relatively inexpensive in production quantities, and has high potential for development into a standard aircraft instrument. In addition to airspeed information, the system can provide data on downwash velocity, direction, and aircraft performance through measurement of induced flow. Iv r ~UNCLASSIFIED Securi:y Classification !DOCMVAX.T CC.OT. DAT A R t I c ity 455."Ific~tiol ofl itit fh-e cbeft