NACA-RM-L52K20

Abstract

INTRODUCTION <br>Successful accomplishment of aircraft flight at transonic and supersonic speeds has served to place increased emphasis on the dynamic behavior of aircraft. The type of behavior referred to here concerns motions of the aircraft as a whole as compared to motions of component parts usually referred to as flutter. Dynamic instability of the lateral and directional modes of motion is a problem that has occupied the designer's attention for some time. A trend toward deterioration of the damping of the longitudinal motion of aircraft operating in the transonic region has also been experienced. This decrease in damping, as measured by cycles to damp, occurs because of the high altitude at which such flights are usually conducted and because of an actual decrease in the dimensionless aerodynamic damping-in-pitch derivatives at transonic speeds for some aircraft configurations (refs. 1 and 2). <br>The present paper summarizes the available experimental data obtained by the National Advisory Committee for Aeronautics on pitch-damping derivative measured in flight at transonic and low supersonic speeds. Most of the data contained herein were obtained from rocket propelled models of airplane or missile configurations flown at the Langley Pilot less Aircraft Research Station at Wallops island, Vs. Some data are also shown for several piloted airplanes obtained from flights at Ames Aeronautical Laboratory and the NACA High-Speed Flight Research Station at Edwards, Calif. <br>Some of the damping information presented herein has been published previously as parts of general longitudinal-stability investigations and some is, as yet, unpublished. In the present paper the&#8211;damping data are compared with each other and with values calculated by the usual methods.