From Introduction: "Experimental investigations of air-induction systems in which the air flows of two intakes join in a common duct have inducted that many of these systems are subject to air-flow instability at low inlet-velocity ratios. Therefore, an analysis has been made to determine a proper basis for an explanation and to provide a more quantitative explanation of the flow instability and the flow reversal. This report presents the results of this analysis."

Report presenting a method for calculating the pressure drop of a high-speed compressible fluid in a constant-area duct under the simultaneous action of friction and heat transfer. The temperature distribution assumed in the development of the working chart can be made to closely approximate, in on one or two steps, the temperature distributions found in the cooling passages of ramjet and tail-pipe-burner combustion chambers.

Note presenting an analysis for interpreting results of dynamic tests of a model investigated at full-scale Mach number in terms of the corresponding full-scale body. The analysis indicates that dynamic similarity for such a condition can be closely approximated although the effect of gravity is not to scale.

Report presenting an analytical investigation of the performance of a turbojet engine with air bled off at the compressor outlet. A wide range of engine and flight conditions are covered and air bleeds of 0 to 15 percent of the air mass flow are considered. Results are provided in the form of generalized performance charts that are applicable to a wide range of operating conditions.

Report presenting a wind-tunnel investigation of a partial model of a conventional fighter airplane to determine the effects of rate of change of angle of attack on its maximum lift. The results indicated that the maximum lift coefficient increased linearly with pitching velocity up to a limit value of the lift coefficient which depended on the Mach number.

Note presenting an investigation conducted to determine the effects of an aging treatment on the life of a small cast Vitallium gas-turbine blades operated at a blade temperature of approximately 1500 degrees Fahrenheit and a stress of 20,000 pounds per square inch at the blade-failure plane. Twenty blades that were aged for 48 hours at 1500 degrees Fahrenheit were compared with 33 unaged blades. Results regarding turbine evaluation and metallurgical examination are provided.

Report presenting an experimental investigation on the thermal and hydrodynamical behavior of air flowing along a steam-heated plate to which were attached cylindrical fins. The data indicate that the principal criterion for the application of the equations for heat transfer along unfinned flat plates is the initiation of a thermal boundary layer.

Note presenting a method of calibrating airspeed installations on airplanes at transonic and supersonic speeds by use of instrumentation in the airplane only. A description of the method and some suggestions for increasing the accuracy of the method are provided.

From Summary: "An extremely simple computational method is established for obtaining circulatory flows around given bodies to a high degree of accuracy for flows satisfying the linear pressure and specific-volume equation of state. The method depends not on an integral equation but on the transformation from the holograph to the physical plane involving the determination of an arbitrary analytic function. The determination of the arbitrary analytic function by elementary means results in a close approximation of the given body."

Note presenting a method for calculating the pressure distribution and damping in steady roll at supersonic Mach numbers of thin, flat, sweptback wings with all edges straight and subsonic. It can be adapted to wings with negative rake at the tips, but the method is developed only for wings with streamwise tips.

Report presenting an investigation to determine the properties of a boron carbide-iron ceramal. The properties were compared to the properties of hot-pressed boron carbide. The properties evaluated were room- and elevated-temperature modulus of rupture, resistance to fracture by thermal shock, density, and oxidation characteristics.

Report presenting an investigation in the 20-foot free-spinning tunnel to determine whether the effectiveness of a spin-recovery parachute would be influenced by a reduction, through the use of a shock absorber, or the opening shock load. The results indicated that a given spin-recovery parachute was effective with or without a rubber shock absorber installed in the parachute towline. Results regarding the effect of the shock absorber on spin-recovery characteristics and effect of porosity and towline length on shock load are provided.

Report presenting the wing-aileron coefficients of oscillating air forces for two-dimensional supersonic flow for a variety of Mach numbers. Various ratios of control-surface chord to airfoil chord are employed in the calculation and for each combination of chord ratio and Mach number, approximate 35 values of reduced frequency are utilized.

Note presenting the lift and damping in roll for families of thin sweptback tapered wings with raked-in and cross-stream wing tips. Equations were derived for wings that are contained within a boundary formed by the Mach lines, which means that the wing has subsonic leading edges, supersonic trailing edges, and supersonic wing tips.

"The method of computing velocity and pressure distributions along wing profiles under the assumption of the simplified density-speed relation, outlined in NACA Technical Note 1006, is extended to the case of a nonsymmetrical profile and a flow with circulation. The shape of the profile, the speed of the undisturbed flow, and a parameter determining the angle of attack may be prescribed. The problem is reduced to a nonlinear integral equation which can be solved numerically by an iteration method" (p. 1).

Report presenting charts to provide a convenient means for obtaining the derivatives of rotor resultant force, rotor pitching amount about the helicopter center of gravity, and rotor torque with respect to rotor angle of attack, forward speed, rotor speed, and collective pitch.

Report presenting information on the axial-load fatigue behavior of unnotched specimens of 24S-T3 and 75S-T6 aluminum alloys and normalized SAE 4130 steel. The primary objectives of the investigation were to determine fatigue strengths and measurements of damage due to stress level are provided. Results regarding static strength tests, fatigue strength tests, fatigue damage tests, and results at high and low speeds are provided.

Note presenting an investigation to determine the static-thrust performance of a coaxial helicopter rotor with blades tapered both in plan form and thickness ratio in the full-scale tunnel. Tests of the coaxial-rotor and single-rotor configurations were made for a range of blade-pitch setting and for a range of tip speed up to 500 feet per second. Results regarding the hovering performance, effect of variation in directional control, and variation of rotor figure of merit with ratio of thrust coefficient are provided.

Note presenting a general steady through-flow theory of nonviscous fluid in turbomachines of arbitrary hub- and casing-wall shapes with subsonic or supersonic velocity. The theory is applicable to both direct and inverse problems and is derived primarily for use in turbomachines with thin blades of high solidity with a simple approximate correction factor for blade-thickness effect.

Note presenting a basic theory of generalized linearized supersonic conical flow for both inside and outside the Mach cone, which was developed and applied to several specific problems including unsteady-flow conditions. A triangular lifting wing in pitching and rolling with both subsonic and supersonic leading edges was investigated and pressure coefficients were obtained.

Report presenting a linearized solution for the problem of plastic deformation of a thin plate with a circular hole in the strain-hardening range. It is based on the deformation theory of plasticity for finite strains.

"Liquid-water content, droplet size, and temperature data measured during 22 flights in predominately stratiform clouds through the 1948-49 and the 1949-50 winters are presented. Several icing encounters were of greater severity than those previously measured over the same geographical area, but were within the limits of similar measurements obtained over different terrain within the United States. An analysis of meteorological conditions existing during the 74 flights conducted for four winters indicated an inverse relation of liquid-water concentration to maximum horizontal extent of icing clouds" (p. 1).

Note presenting a method for the determination of the spanwise load distribution of a flexible swept wing at subsonic speeds. The method is based on a relaxation approach using aerodynamic loadings obtained from previously published work based on Weissinger's simplified lifting-surface theory together with simple beam theory.

Note presenting the equations governing the three-dimensional compressible laminar boundary layer with variable viscosity and thermal conductivity, which are shown to be simplified by the introduction of a two-component vector potential, the use of a transformation to change the equations into nearly incompressible form, and the use of a further transformation that changes the equations into nearly Cartesian form when a coordinate system appropriate to axial or conical symmetry is used. Problems involving conical potential flow are also discussed.