NACA-RM-L56E29

Abstract

INTRODUCTION <br>The design trend of high-speed airplanes has resulted in certain combinations of airplane aerodynamic and mass characteristics which have sometimes allowed some of these airplanes to attain attitudes in certain maneuvers which have subjected the rearward fuselage and tail surfaces to dangerously high loads. It therefore has become important that the airplane designer be furnished with more information as a basis for structural design and also to provide more information required for improved procedures for estimating the tail contribution to the lateral and directional stability. (See refs. 1 to 4.) Existing procedures for estimating the load on some tail configurations at low angles of attack and at subsonic and supersonic speeds are pointed out in reference 2. Methods for calculating these loads at low angles of attack are not necessarily valid for calculating the loads at higher angles of attack, since the vertical tail may be operating in a highly disturbed flow field from the wing and fuselage. Therefore, any calculations should be based on an understanding of the strength and position of the wing and fuselage flow field at the tail. Reference 5 presents some theoretical and experimental results of tail flow-field studies and reference 2 outlines several procedures that may be used in order to determine the strength and position of the trailing vortices from the wing and fuselage. <br>The purpose of the present investigation was to determine experimentally at high subsonic speeds the static lateral and directional stability characteristics and the static tail loads in sideslip on a model having a highly tapered swept wing and the horizontal tail in either of two positions. The wing was of aspect ratio 3, taper ratio 0.14, and had NACA 65A006 airfoil sections. The leading edges of the wing and of the delta horizontal tail were swept back 45⁰. <br>Tests were made both with the horizontal tail located at the tip of the swept vertical tail and with the tail on the center line of the fuselage. In addition to tests of the complete model, breakdown tests were made in order to determine the contribution of the tail surfaces to static lateral and directional stability and tail-loads characteristics of the model with and without the wing. Test Mach numbers ranged from 0.80 to 0.92 with corresponding Reynolds numbers ranging from about 4.0 x 10⁶ to 4.2 x 10⁶ based on the wing mean aerodynamic chord. For some tests, the model angle of attack was varied from -2⁰ to approximately 23⁰ at sideslip angles of 4⁰ and -4⁰. In another series of tests the model sideslip angle was varied from -4⁰ to approximately 12⁰ at several selected angles of attack. <br>Results presenting the static longitudinal stability and the rolling stability derivatives of the model are given in references 6 and 7, respectively.