Report presenting testing in high-speed flight with a fighter airplane to determine the effect of chordwise pressure distribution resulting from a minor modification in the contour of the wing upper surface. A faired bulge was added to the contour and chordwise pressure distributions were obtained on the original and modified contours.

Note presenting symbols and definitions of various airspeed terms that have been adopted as standard by the NACA Subcommittee on Aircraft Structural Design. the equations, charts, and tables required in the evaluation of true airspeed, calibrated airspeed, equivalent airspeed, impact and dynamic pressures, and Mach and Reynolds numbers have been compiled.

Note presenting an investigation of the effects of tip dihedral on lateral stability and control characteristics by flight tests of models in the free-flight tunnel. The results indicate that at high lift coefficients, tip dihedral may cause a lightly damped lateral oscillation, which does not occur with full-span dihedral at similar values of effective dihedral and directional stability.

"A spoiler-type lateral-control system has been developed for use on the Northrop P-61 airplane. The lateral-control system is to be used with large-span flaps and consists of a thin circular arc spoiler, linked with a short-span plain aileron located just outboard of the spoiler. This unconventional lateral-control system has been accepted with enthusiasm by the pilots who have flown the airplane" (p. 1).

Note presenting tests at high speeds to determine the drag of models, simulating propeller shanks, in the form of a circular cylinder and three airfoils with the rear 25 percent chord cut off. The results indicated that the drag of the airfoils was lower than that of the cylinder over the Mach number range investigated.

Note presenting temperatures of a turbosupercharger rotor measured in flight for a variety of conditions by thermocouples, the leads of which were brought away from the turbine by means of rotating slip rings and stationary brushes. A consistent and almost linear relation was shown between turbine temperature at the outer edge of the rim and the effective exhaust-gas temperature at the surfaces of the blades on three successive flights at cruising power.

Report presenting an investigation of elevators with three hinges to evaluate the structural hinge-moment increments resulting from changing the elevator angle when the hinge axis is distorted under load. The analytical results are compared to test data obtained for a full-scale semispan fighter-type horizontal tail surface in the 16-foot high-speed tunnel.

Report presenting flight tests to determine the cooling characteristics of a two-row radial engine at altitude in a twin-engine airplane and to investigate the accuracy with which low-altitude cooling-correlation equations can be used for making cooling predictions at higher altitudes. Satisfactory correlation of the cooling variables was obtained at both altitudes by the NACA-cooling method.

Report presenting a study of accurate values of the specific heat for dry air applied to the calculation of work required to compress dry air. Two charts are provided that allow the work of compression to be determined from the initial temperature, overall pressure ratio, and either the compression exponent or adiabatic efficiency of the compressor.

Note presenting a well-known method of generating stream functions of an incompressible fluid flow, which involves taking the imaginary part of an analytic function of a complex variable. This paper is specifically devoted to a detailed discussion of performing computations related to obtaining flow patterns of compressible fluid from analytic functions of a compressible fluid. An example is also provided to illustrate the method.

Note presenting an extension of the analytical methods used to successfully in the theory of an incompressible fluid to the case of a compressible fluid.

"As a first step toward the computation of the velocity distribution along a wing profile of arbitrary shape in a compressible fluid, the circulation-free flow around a symmetrical profile is treated under the assumption of the simplified density-speed relation due to Tchaplygin, Karman, and Tsien. The velocity distribution problem is reduced to a non-linear integral equation which is solved by a fairly rapidly convergent iteration method. Numerical examples are given" (p. 1).

Note presenting an extension of the method of computing the pressure distribution along a symmetrical profile of arbitrary shape given in a previous technical note under the assumption of a linearized pressure-volume relation to the case of an everywhere subsonic flow satisfying the rigorous adiabatic equation of state. The actual applicability of the method depends on the development of efficient procedures for numerical integration of linear partial differential equations with variable coefficients. Tables and graphs of functions needed for the computation are given.

Note presenting a method by which the directional stability derivative, which is the rate of change of yawing-moment coefficient with sideslip angle, can be evaluated for a conventional airplane from flight records of a lateral or directional oscillation. When applied to conventional airplanes flying at low to moderate lift coefficients, the assumptions involved in this simplified method produce negligible error.

"Dynamic yawing effects on vertical tail loads are considered by a theory of flat yawing maneuvers. A comparison is shown between computed loads and the loads measured in flight in a fighter airplane. The dynamic effects were investigated on a large flying boat for both an abrupt rudder deflection and a sinusoidal rudder deflection" (p. 1).

Report presenting a two-dimensional wind-tunnel investigation of three low-drag airfoil sections equipped with sealed internally balanced control surfaces designed for use as vertical-tail, horizontal-tail, and wing sections. Testing included determination of control-surface effectiveness and hinge moments and airfoil section drag characteristics. Results regarding vertical-tail section, horizontal-tail section, wing section, and effect of sudden movement of transition on airplane control-surface characteristics are provided.

Report presenting a two-dimensional wind-tunnel investigation made of two interchangeable sealed 0.22-airfoil-chord internally balanced ailerons on an NACA 65(sub 112)-213 airfoil. One aileron tested was of true airfoil contour and the other was modified by partly eliminating the cusp near the trialing edge. Results regarding aileron effectiveness, aileron hinge moments, lift, drag, and airfoil pressure distribution and critical Mach number are provided.

Report presenting a two-dimensional wind tunnel investigation for the purpose of developing a suitable double slotted flap on a 14-percent-thick modified NACA 66-series-type airfoil section. Section aerodynamic characteristics of the airfoil with various double-slotted-flap arrangements are presented. Results regarding the airfoil with the flap retracted and flap deflected are provided.

Report presenting a method for calculating the lift and drag due to lift of point-forward triangular wings and a restricted series of sweptback wings at supersonic speeds.

Note presenting an application of the theory of Lagrangian multipliers to the problem of finding both upper and lower limits to the true compressive buckling stress of a clamped rectangular plate.

Note presenting a description of the synthesis of isobutylbenzene, sec-butylbenzene, and tert-butylbenzene in 11-gallon quantities. The physical properties are tabulated and freezing curves are plotted for the five hydrocarbons.

Report presenting testing on a wire strain gage of representative design to determine zero shift after straining at room temperature, error in indicated strains at high and low temperature, and changes in calibration factor and zero shift after exposure to heavy weathering. Results regarding the measurements of zero shift after 1 to 10 cycles of straining and testing to determine whether or not zero shift was removed by prestraining reappeared after the gages were left unstrained are provided.

Report presenting the results of calibrations to determine axial and transverse strain sensitivities for 15 types of single-element, multistrand wire strain gages. The gages were separated into those which had positive average ratios of transverse sensitivity and those which had negative transverse sensitivity.

Note presenting a study of the altered surface layers found on nitrided-steel piston rings run in nitrided-steel cylinder barrels in order to determine the physical and chemical characteristics of the altered layers and the mechanism by which the coating layers were formed. An electron and a light microscope were used to study different aspects of the materials.