"The flexural vibration of a rotating propeller blade with clamped shank is analyzed with the object of presenting, in matrix form, equations for the elastic bending moments in forced vibration resulting from aerodynamic forces applied at a fixed multiple of rotational speed. Matrix equations are also derived which define the critical speeds end mode shapes for any excitation order and the relation between critical speed and blade angle. Reference is given to standard works on the numerical solution of matrix equations of the forms derived" (p. 1).

Contains results of calculations made to determine the neutral oscillatory stability boundaries, period and time to damp of the oscillatory mode, and motions following disturbances. The calculations were made for Mach numbers of 0.75 and 2.3 at an attitude of 35,000 feet and for the landing condition at sea level.

Report presenting generalized radiation charts for the calculation of the irradiation from water vapor, carbon dioxide, ozone, and the earth in terms of appropriate parameters. Nocturnal irradiation was found to decrease greatly as a function of altitude and meteorological conditions.

Report presenting an investigation of the take-off and landing behavior in waves of models of a hypothetical flying boat with hull length-beam ratios of 6 and 15. The flying boat had a design gross weight of 75,000 pounds, a wing loading of 41.1 pounds per square foot, and a power loading of 11.5 pounds per brake horsepower for take-off. Results regarding the landing behavior, spray characteristics, and taxiing and take-off behavior are provided.

From Summary: "A theoretical investigation of the velocity profiles for laminar mixing of a high-velocity stream with a region of fluid at rest has been made assuming that the Prandtl number is unity. A method which involves only quadratures is presented for calculating the velocity profile in the mixing layer for an arbitrary value of the free-stream Mach number. Detailed velocity profiles have been calculated for free-stream Mach numbers of 0, 1, 2, 3, and 5."

Note presenting landing tests made with the PB2Y-6 flying boat to determine the effect of production step vents and forebody longitudinal steps on skipping. Skipping was found to occur at higher landing trims without either step vents or longitudinal steps. The steps were found to constitute a powerful method for improving the landing stability.

Report presenting comparisons of the structural efficiency of panels with straight-web and curved-web Y-section stiffeners. In the high-stress region in which failure is at least in part associated with local buckling, panels with curved-web Y-section stiffeners have higher structural efficiencies than panels with straight-web Y-section stiffeners, which is evidenced by higher average stresses at failure, smaller stiffener heights, or wider average spacing of rivet lines.

"Direct-reading design charts are presented for 24S-T aluminum-alloy flat compression panels having longitudinal formed Z-section stiffeners. These charts make possible the direct determination of the stress and all the panel proportions required to carry a given intensity of loading with a given skin thickness and effective length of panel" (p. 1).

"Direct-reading design charts are presented for 24S-T aluminum-alloy flat compression panels having longitudinal straight-web Y-section stiffeners. These charts make possible the direct determination of the stress and all the panel proportions required to carry a given intensity of loading with a given skin thickness and effective length of panel" (p. 1).

Note presenting a prismatic-float forebody with an angle of dead rise of 40 degrees that was subjected to smooth-water impacts in the impact basin. The tests were made at fixed trims of 3, 6, 9, and 12 degrees for a range of flightpath angles from approximate 2 to 22 degrees. The data are presented and converted into dimensionless variables for correlation of the experimental results with hydrodynamic impact theory and for comparison of the runs among themselves.

Note presenting a wind-tunnel investigation made of the lateral-control characteristics of a thin, low-drag, semispan wing equipped with three configurations of circular plug ailerons and a full-span, 25-percent-chord, slotted flap. The investigation was performed through a Mach number range of 0.13 to 0.61. Results regarding wing aerodynamic characteristics, aileron control characteristics, comparison of lateral-control characteristics of the three configurations of circular plug aileron, comparison of lateral-control characteristics of the circular plug ailerons, a conventional plug aileron, and a retractable aileron, and a comparison of lateral-control characteristics of the circular plug ailerons with those of a sealed plain aileron are provided.

A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.

Report presenting an investigation of the effect of the rate of change of angle of attack on the maximum lift coefficient of a pursuit airplane equipped with a low-drag-type wing in stalls of varying abruptness over a range of Mach and Reynolds numbers. Maximum lift coefficients were found to increase linearly with increasing rate of change of angle of attack per chord length of travel up to the maximum rate attained in the tests.

The free turbulent mixing of a supersonic jet of Mach number 1.6 has been experimentally investigated. An interferometer, of which a description is given, was used for the investigation. Density and velocity distributions through the mixing zone have been obtained. It was found that there was similarity in distribution at the cross sections investigated and that, in the subsonic portion of the mixing zone, the velocity distribution fitted the theoretical distribution for incompressible flow. It was found that the rates of spread of the mixing zone both into the jet and into the ambient air were less than those of subsonic jets.

A low-scale wind-tunnel investigation was conducted in rolling flow to determine the effects of aspect ratio and sweep (when varied independently) on the rolling stability derivatives for a series of untapered wings. The rolling-flow equipment of the Langley stability tunnel was used for the tests. The data of the investigation have been used to develop a method of accounting for the effects of the drag on the yawing moment due to rolling throughout the lift range.

An investigation was conducted on an 0.08-scale semispan model of the Chance Vought XF7U-1 airplane in the Langley high-speed 7- by 10-foot tunnel in the Mach number range from 0.40 to 0.97. The results are compared with those obtained with an 0.08-scale sting-mounted complete model tested in the same tunnel and with an 0.026-scale semispan model tested by the wing-flow method. The lift-curve slopes obtained for the 0.08-scale semispan model and the 0.026-scale wing-flow model were in good agreement but both were generally lower than the values obtained for the sting model.

Report presenting an investigation of two NACA 6-series airfoils, the NACA 64(sub)1-212 and NACA 65A109 with leading edge slats and split flaps deflected 60 degrees. Information about optimum slat positions, airfoil section lift characteristics, pitching-moment characteristics, and effect of roughness on the lift characteristics was obtained.

Memorandum presenting the low-speed lateral-control characteristics of a 37 degree sweptback semispan wing of aspect ratio 6 and NACA 64-series airfoil sections in the 19-foot pressure tunnel. The investigation included the measurement of the hinge-moment characteristics of an aileron and the rolling-effectiveness characteristics of the aileron and two configurations of spoilers.

Note presenting an investigation of a two-blade and a three-blade propeller on a slender-nose fighter airplane in climb and at high speed.

Note presenting a study of conditions in the Pacific Ocean to investigate several characteristics in the sea and wind that are of importance in the structural design of flying boats and seaplanes: wave height and frequency of occurrence, wave length-height ratio and frequency of occurrence, wave velocity and its relation to wave lengths, wind velocity, and wave shape.

An investigation was conducted to determine the performance characteristics of the axial-flow supersonic compressor of the XJ-55-FF-1 turbo Jet engine. The test unit consisted of a row of inlet guide vanes and a supersonic rotor; the stator vanes after the rotor were omitted. The maximum pressure ratio produced in the single stage was 2.28 at an equivalent tip speed or 1814 feet per second with an adiabatic efficiency of approximately 0.61, equivalent weight flow of 13.4 pounds per second. The maximum efficiency of 0.79 was obtained at an equivalent tip speed of 801 feet per second.

Report discussing an investigation of two sweptback wings of different plan form in order to determine the effects of adding a triangular area to the inboard section of a conventional sweptback wing as a way to create a wing with two stages of sweepback. Lift, drag, and pitching-moment characteristics are provided for a range of Mach numbers.

From Summary: "By the use of a form of the Prandtl-Glauert method that is valid for three-dimensional flow problems, the value of the maximum incremental velocity for compressible flow about thin ellipsoids at zero angle of attack is calculated as a function of the Mach number for various aspect ratios and thickness ratios. The critical Mach numbers (within the accuracy of the Prandtl-Glauert method) of the various ellipsoids are also determined. The results indicate an increase in critical Mach number with decrease in aspect ratio which is large enough to explain experimental results on low-aspect-ratio wings at zero lift."

Report presenting an investigation of the exhaust of corrosive attack in an aluminum alloy wing employing an exhaust-gas-air mixture as a heating medium for ice prevention. There were no cases of structurally serious corrosion on either painted or plain specimens removed from the wing for detailed microscopic and metallurgic examination.