NACA-TN-1080

Abstract

INTRODUCTION <br>Dynamic-stability calculations for an airplane require knowledge of values of the damping-in pitch derivative c_mq (the pitching-moment coefficient due to pitching velocity) and the damping-in-yaw parameter c_nr ( the yawing-moment coefficient due to yawing velocity). At the present time, however, very little experimental data on these derivatives for modern airplanes are available. <br>The damping derivatives c_mq and c_nr have been measured in the Langley free-flight tunnel during stability investigations as an aid in analyzing the stability characteristics of some models. These measurements are summarized herein to provide a source of experimental data, and a limited analysis of the data and a comparison with calculated results are also presented. The values of c_nr and c_mq were determined experimentally by the free-oscillation method described in reference 1 and 2. The calculations were made by the methods of references 2 to 6 <br>Data are presented for a rectangular wing and for 13 complete airplane models, five of which are tailless designs. The term "tailless" refers to an airplane with no horizontal tail; however, such designs generally incorporate some type of vertical tail. The term "conventional" in this paper refers to airplanes other than tailless airplanes. Values of c_nr and c_mq over the normal lift range are presented in most cases. The effects of tail area, tail length, flap deflection, and power on the damping in yaw and pitch are shown.