NACA-RM-L52E02

Abstract

INTRODUCTION <br>An investigation is currently being conducted by the National Advisory Committee for Aeronautics to determine the dynamic response characteristics of research airplanes through the transonic speed range. As a part of this investigation, some results on the dynamic longitudinal response characteristics of the Douglas D-558-II research airplane have been obtained. These data are somewhat complete below a Mach number of 0.85 for two altitude ranges. Some data are presented for higher test Mach numbers and altitudes because of the general interest in data of this type. <br>Of the several methods of obtaining the frequency response of freeflight dynamical systems, the pulse-disturbance technique was used because a minimum of flight time and instrumentation is required. Also, no special device is necessary to actuate the input control. By a Fourier analysis of the airplane response to an elevator- pulse, the frequency response of the airplane has been obtained. These results have been reduced to airplane stability derivatives. <br>These tests were conducted over a Mach number range of 0.60 to 0.96 at altitudes ranging from 21,000 to 43,000 feet. For purposes of analysis the data have been divided into three altitude ranges: 21,000 to 25,000 feet, 28,000 to 33,000 feet, and at 37,500 and 43,000 feet.