TECHNICAL D-323 NOTE

NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONTECHNICAL NOTE D-323A FLIGHT STUDY OF A POWER-OFF LANDING TEC_NIQUEAPPLICABLE TO RE-ENTRY VEHICLESBy Richard S. Bray, Fred J. Drinkwater III,and Maurice D. WhiteSUMMARYA power-off landing technique, applicable to aircraft of configurationspresently being considered for manned re-entryvehicles, has been developedand flight tested at Ames Research Center. The flight tests used two con-figurations of an airplane for which the values of maximum lift-drag ratioswere 4.0 and 2.8. T_enty-four idle-power approaches were made to an 8000-foot runway with touchdown point and airspeed accuracies of _+600 feet and±I0 knots, respectively.The lauding pattern used was designed to provide an explicitly definedflight path for the pilot and, yet, to require no external guidance otherthan the pilot's view from the cockpit. The initial phase of the approachpattern is a constant high-speed descent from altitude aimed at a groundreference point short of the runway threshold. At a specified altitudeand speed, a constant g pull-out is made to a shallow flight path alongwhich the airplane decelerates to the touchdown point.Repeatability and safety are inherent because of the reduced numberof variables requiring pilot judgment, and because of the fact that amissed approach is evident at speeds and altitudes suitable for safeejection. The accuracy and repeatability of the pattern are indicated bythe measured results.The proposed pattern appears to be particularly suitable forconfigurations having unusual drag variations with speed in the lowerspeed regime, since the pilot is not required to control speed in thelatter portions of the pattern.INTRODUCTIONOne of the present concepts of a manned satellite vehicle is anairplanelike configuration which is capable of normal aerodynamic flightafter re-entering the atmosphere. Considerations of weight suggest thatthe vehicle be without means of propulsion at this stage of the flight,