Flight Dynamics and Controls

The NASA Dryden Flight Research Center has flight tested two X-29A aircraft at low and high angles of attack. The high-angle-of-attack tests evaluate the fea-sibility of integrated X-29A technologies. More specif-ic objectives focus on evaluating the high-angle-of-attack flying qualities, defining multiaxis controllabili-ty limits, and determining the maximum pitch-pointing capability. A pilot-selectable gain system allows exam-ination of tradeoffs in airplane stability and maneuver-ability. Basic fighter maneuvers provide qualitative evaluation. Bank-angle captures permit qualitative data analysis. This paper discusses the design goals and approach for high-angle-of-attack control laws and provides results from the envelope expansion and handling qual-ities testing at intermediate angles of attack. Compari-sons of the flight test results to the predictions are made where appropriate. The pitch rate command structure of the longitudinal control system is shown to be a val-id design for high-angle-of-attack control laws. Flight test results show that wing rock amplitude was overpre-dicted and aileron and rudder effectivenesses were underpredicted. Flight tests show the X-29A airplane to be controllable in all axes, with no nose wandering, up to 40 ° angle of attack