Report presenting wind tunnel testing to investigate the possibility of reducing the hinge moments of a control surface by beveling the trailing edge. Tests were made with a 9-percent-thick airfoil with a 30-percent-chord plain flap. Results regarding the variations of lift and hinge moment, effect of shapes, and pitching moments are provided.

Report presenting lift and elevator hinge-moment characteristics of a horizontal tail with various plain and balanced elevators and mounted on a typical pursuit fuselage as measured in the 7- by 10-foot wind tunnel at attitudes simulating normal-flight and spin conditions. The lift effectiveness of the elevator was practically independent of the size of the aerodynamic balance. Results regarding the fuselage alone and fuselage interference, lift characteristics of fuselage-tail combinations, lift effectiveness of the tab, elevator hinge moments, parameters, effect of yaw on elevator hinge moments, effect of tab on elevator hinge moments, drag, and comparison with two-dimensional data are provided.

Report presenting a method of organizing design calculations for the cooling systems of aircraft power-plant installations for use by representatives of airplane and engine companies invited to participate in the NACA power-plant installation section.

Flow across tube banks was investigated by surveys of total dynamic and static pressure by visualization of the flow through the use of titanium tetrachloride smoke, by thermocouple surveys of heated tubes, and by hot-wire surveys of both heated and unheated tubes. It was found that turbulence increased as the depth of the bank increased and that the broad wake behind each tube affected flow over the succeeding tubes.

Report presenting testing of combinations of an NACA 23012 tapered wing and a circular fuselage with a wedge-shaped rear to determine the effect of wing-fuselage interference on the lateral-stability characteristics. The model configurations represented a high-wing, a mid-wing, and a low-wing monoplane. Results regarding the lateral stability at small and large angles of yaw are provided.

Report presenting an investigation of the pressure-drop characteristics of orifice plates, which has been conducted to facilitate the design of resistances to simulate various types of cooling units. This use of the orifice plates was found to be practical because of the simple construction of the plates, the ease of which pressure drop can be varied by use of corks, and the absence of any large scale effects.

Report presenting testing of a Fairchild XR2K-1 airplane equipped with a wing having a full-span Zap flap and upper-surface ailerons in the full-scale wind tunnel and in flight to determine the characteristics of the flap and ailerons. Results regarding the lift, drag, and pitching-moment coefficients of the airplane and the aileron rolling, yawing, and hinge-moment coefficients were measured at various flap deflections are provided. Maximum rolling velocity and acceleration, yawing velocity, time lag in aileron response, and aileron control forces were also determined.