Flight Evaluation - Aeroflex True Airspeed Vector System

Test airspeed probes are generally pitot-static systems. These systems measure an indicated airspeed which must be corrected for position error and air density deviations from sea-level, standard-day conditions to obtain true airspeed. The pitot-static system is normally inaccurate at low airspeeds and may have a limited acquisition range for angles of attack and sideslip. In this case, directional airflow information must be obtained from an independent source. A true airspeed vector system was developed which measures true airspeed and sideslip angle directly. The system design threshold was 0.1 knot, with omnidirectional sensing of sideslip angle. Successful laboratory and wind tunnel results of prototype systems led to the construction of a production system which was flight-tested on UH-1C and OH-58A helicopters, and an F-51D fixed wing aircraft. The Aeroflex system was tested at five locations on the helicopters. (Modified author abstract)