NACA-RM-L50L29

Abstract

INTRODUCTION <br>The results of investigations of the spin and recovery characteristics of numerous models tested in the Langley is-foot free-spinning tunnel and the Langley 20-foot free-spinning tunnel during the years 1935 to 1946 have been used to establish empirical criterions for satisfactory spin recovery (references 1 and 2) which are generally applicable to airplanes having mass distributions typical of this time period and which are considered of conventional design (that is, having both horizontal and vertical surfaces at the tail end of the airplane). The results of several designs which may be generally termed unconventional or flying wing-type configurations were also available and, because of increased interest in unconventional high-speed airplane configurations, it appeared desirable to evaluate these available results to determine criterions for satisfactory spin recovery similar to those evolved for conventional airplanes. Because the flying-wing and unconventional-type designs often utilized unusual and different methods of obtaining directional control, it was not possible to evaluate their spin-recovery characteristics in terms of a vertical-tail design parameter (tail-damping power factor) in the manner used for conventional designs (reference 1). Also, because of rather limited data available for these configurations, an alternate effective parameter could not be developed at this time. Results available for 12 designs of unconventional and flying-wing-type configurations have been summarized, however, and the more important spin and recovery characteristics are presented in this paper. <br>The effects of mass distribution and center-of-gravity location were determined for many of the models as were the effects of geometric modifications designed in an attempt to improve the spin-recovery characteristics. The investigations included the determination of the effectiveness for spin recovery of Several types of controls which are peculiar to flying-wing and unconventional-type airplanes. <br>The spin and recovery characteristics of each model are presented for the various control configurations, mass distributions, and dimensional configurations tested. Dimensional data, mass data, and a three-view drawing of each of the various free-spinning models are included. The data presented are intended to help designers of unconventional and flying-wing-type airplanes anticipate probable spin and recovery characteristics.