NACA-RM-L54H19

Abstract

INTRODUCTION <br>Among the problems that may be encountered during flight at extremely high altitudes is that of maintaining satisfactory stability and control. High angles of attack would be required for trimmed level flight at high altitudes and in "addition the ability to reach high angles of attack might be required for the purpose of decelerating. <br>In general, it has been found difficult to attain high angles of attack at supersonic speeds with current airplane designs largely because of the increased longitudinal stability that occurs in going from subsonic to supersonic flight and partly because of decreased control effectiveness. (See reference 1 for example.) <br>A possible means&#160;of increasing&#160;maximum angle-of-attack capabilities for conventional tail-rearward designs would be through the use of a canard control surface installed for the dual purpose of reducing the longitudinal stability and providing additional longitudinal control. Such a device, of course, would also reduce the stability at subsonic speeds and at these speeds it would probably be necessary to allow the canard surface to float freely. <br>The present tests were conducted to determine the effectiveness of a&#160;canard-type surface in reducing the static longitudinal stability and l increasing the trim-angle-of-attack capabilities of a model of a supersonic aircraft configuration at a Mach number of 1.89. In order to simulate high altitudes the tests were made at a tunnel stagnation pressure of 2 pounds per square inch absolute corresponding to a Reynolds number of 0.28 x 10⁶ (based on the wing mean aerodynamic chord) and to a pressure altitude of about 88,000 feet.