"Following the law of stress adopted in the Navier-Stokes equations, the configuration of the viscous flow in planes at right angles to the axis of an infinite cylinder is found to be independent of the axial motion of the cylinder. In the limiting case of a yawed or swept wing of very high aspect ratio, certain boundary-layer and separation phenomena are thus determined independently by the crosswise component of velocity" (p. 1).

Report presenting some charts on the reflection of a propeller on the basis of efficiency for application to a light airplane design. Various values of power are covered for several different airspeeds, propeller diameters, and blade numbers.

Note presenting a continuation of a theoretical investigation of the stability of the laminar boundary layer in a compressible fluid. A series of equations are given that provide information related to Reynolds number effects and the physical significance of the stability analysis.

"The stresses in the two spars of a model of a wing having three rectangular cutouts were calculated by the PIBAL method, a modification of Southwell's method of systematic relaxations. The model was built and tested in the Polytechnic Institute of Brooklyn Aeronautical Laboratories and the deflections and strains measured were compared with calculated values. The agreement was found to be satisfactory" (p. 1).

Report presenting a dynamometer-stand investigation to determine the effect of exhaust pressure on the performance of a 12-cylinder liquid-cooled aircraft engine equipped with a conventional exhaust collector. The results are presented in the form of curves that show the effect of exhaust pressure on engine power, charge-air flow, volumetric efficiency, inlet-manifold mixture temperature, exhaust-gas temperature, cylinder-head temperature, and heat rejected to the coolant.

Report presenting theoretical and experimental data for NACA 6A-series basic thickness airfoils, which were designed to eliminate the trailing-edge cusp present in NACA 6-series sections. Results indicated that the section minimum-drag and maximum-lift characteristics of the 6-series and 6A-series airfoil sections are essentially the same. Drag, lift, pitching-moment characteristics, and aerodynamic center are also provided.

Note presenting force tests of two isolated vee-tail surfaces with various amounts of dihedral made to provide an experimental verification of a simplified vee-tail theory and the results are presented which were found to be in good agreement with calculations of previous reports. Plots of the basic test data and summaries of the data in the form of plots of the variation of static-stability derivatives and control-effectiveness parameters with dihedral angle are included.

Report presenting a correlation of the experimental and calculated effects of the product of inertia on the stability of lateral oscillations of airplanes. The experimental and calculated boundaries were in good agreement with one another, but neglecting the product of inertia led to wide discrepancies. Results regarding stability and its influence on general flight behavior are provided.

Report presenting a set of charts for the convenient determination of flow conditions behind a shock wave and at the surface of inclined planes and axially symmetric cones located in a uniform frictionless supersonic air stream. Shock angle, static-pressure coefficient, static-pressure ratio, total-pressure ratio, Mach number ratio, and velocity ratio for two-dimensional and conical flow fields are plotted for a range of free-stream Mach numbers.

Note presenting the relation between knock limit and blend composition of selected aviation fuel components individually blended with virgin base and with alkylate as determined in a full-scale air-cooled aircraft-engine cylinder. Results regarding mixture-response curves, relation of knock limit to blend composition, and correlation of knock ratings are provided.

Note presenting comparisons of theoretical and experimental airfoil lift coefficients and pressure distributions made for two cascades of entrance vanes and three cascades of blower blades with NACA 6-series airfoils, and for one cascade of turbine blades. Results regarding the entrance vanes, blower blades, turbine blades, and possibilities of three-dimensional effects are provided.

Note presenting analytical comparisons of weights and volumes for flat-plate heat exchangers with the same calculated thermal output and friction pressure drop for three different fin configurations, including no fins, fins in both the air and exhaust gas passages, and fins in the air passages only. Two different heat exchangers were used and compared with predicted weights and volumes.

Note presenting observation of the icing zones present in a warm front cloud system made during one of a series of flights designed to investigate the meteorological conditions conducive to the formation of ice on aircraft.

Report presenting an investigation in the two-dimensional low-turbulence tunnel to find the effects of boundary-layer control on the aerodynamic characteristics of the NACA 65(sub 4)-421 airfoil section with a boundary-layer-control suction slot at 0.45 airfoil chord and a 0.32-airfoil-chord double slotted flap. The airfoil is designed primarily to obtain a high maximum lift coefficient. Results regarding lift and drag characteristics are provided.

Report presenting high-speed wind-tunnel tests to determine the aerodynamic characteristics of an NACA 6-series airfoil section cambered to have critical Mach numbers higher than those for an airfoil with the same design lift coefficient with a uniform-load type of mean camber line. Comparisons are made between the characteristics of the modified airfoil and those of the NACA 66-210 airfoil with a uniform-load type of mean camber line.

Note presenting an approximate method for determining the convective cooling requirement in the laminar boundary layer region of a body of revolution in high-speed flight that was developed and applied to a sample body. The convective cooling requirements were found to be small for the range of Mach numbers considered, but increased rapidly with increasing Mach number.

Note presenting an investigation to provide a means for calculating the heat required for the prevention of fog formations on the inside surfaces of single-panel bullet-resisting windshields during diving flight. An analysis was made to provide relationships for the heat required considering the transient heating of the windshield during diving flight.

Report presenting testing of arc-welded butt joints in a 1/8-inch SAE 4130 steel sheet of aircraft quality under various conditions of welding and heat treatment in order to evaluate the effects of specific welding-technique factors on the strength of the joints. Results regarding static tension tests and fatigue tests are provided.

Note presenting an investigation conducted to determine the effect of power and full-span slotted flaps on the longitudinal stability and control characteristics of a single-engine high-wing airplane. The model was tested at three power conditions: propeller off, propeller windmilling, and power on, and with the flap neutral, single slotted flap, and double slotted flap. The results indicated that deflection of the double slotted flap produced almost twice as much lift increment as did the deflection of the single slotted flap.

"Steady, diabatic (nonadiabatic), frictional, variable-area flow of a compressible fluid is treated in differential form on the basis of the one-dimensional approximation. The basic equations are first stated in terms of pressure, temperature, density, and velocity of the fluid. Considerable simplification and unification of the equations are then achieved by choosing the square of the local Mach number as one of the variables to describe the flow" (p. 1).

Note presenting an investigation in the free-flight tunnel to obtain an experimental verification of the theoretical rudder-free dynamic stability characteristics of an airplane model equipped with a rudder with positive floating tendencies and various amounts of friction in the rudder system. Results regarding the rudder-free stability without friction and with friction are provided.

Note presenting theories of bending and torsion as applied to the problem of calculating the deflections in aircraft shell structures, particularly of wings. Bending as well as torsional deflections are discussed for wings without or with cut-outs.

Report presenting tests to determine the effect of heat on the pressure drop through radiator tubes made to establish the adequacy of previously developed theory. Results regarding the evaluation of incompressible pressure drop, tubes with smooth entrances, and tubes with transition fixed are provided.

Note presenting an analytical method for calculating the hydrodynamic impact loads and motions experienced by seaplane floats and hulls with scalloped (fluted) bottoms. The analysis, which is applicable to floats with cross sections of any shape, considers that the flow about an immersing planing bottom occurs largely in transverse flow planes which are normal to the keel.