NACA-RM-L52A23

Abstract

INTRODUCTION <br>The lack of information on the aerodynamic balancing of controls in the transonic-speed range has led to the installation of powerful boosts in the control systems of airplanes to enable the performance requirements to be met. The power-boosted control, although quite successful from the standpoint of effectiveness, has some disadvantages: The required mechanism occupies considerable space which with the thinner wings could become critical, considerable power is required to operate the control systems, and a manually operate control system must often be provided in addition to the power boost for positive control in the event of boost failure. It is quite possible that the size of the boost might be materially reduced or even eliminated entirely if more information were available on methods of aerodynamically balancing controls at transonic speeds. The National Advisory Committee for Aeronautics is engaged, at the present time, in a research program designed to provide more information on this subject. One method of balance which has been successful at low speeds and which might be adapted to present-day high-speed aircraft is the balancing tab. It was the purpose of this investigation to determine whether a balancing tab would maintain its effectiveness through the transonic-speed range. No attempt has been made to provide design information by varying the tab geometry other than to change the chordwise location of the tab. <br>The three tabs used in the investigation has the same plan form which consisted of a rectangular lifting surfaces attached to or near the flap trailing edge. The half-span tabs were centered along flap span. The chordwise positions in which the tabs were tested are indicated by their respective names: Inset tab, one which lies within the plan form of the main control; attached tab, one attached to the control trailing edge; and detached tab; one which is located behind the control and supported by booms. <br>Lift, rolling-moment, and hinge-moment characteristics were obtained over a limited angle-of-attack and deflection range at Mach numbers from 0.7 to 1.1.