Note presenting free-spinning-tunnel tests performed with a model of a typical fighter-type airplane to determine the effect of a 40 degrees sweepback on the spin and recovery characteristics. The characteristics were obtained for both a swept-wing and an unswept-wing configuration for a range of typical fighter loading conditions and two tail designs. The results indicated that for the model with a tail design considered unsatisfactory as regards spin recovery, sweeping the wings back 40 degrees improved the recovery characteristics.

Report presenting performance data on a helicopter rotor in flight over a range of combinations of thrust coefficient and tip-speed ratios, which included combinations intended to result in blade stalling. The study indicated that calculated angle of attack of the retreating tip should be a useful parameter for adequately defining the conditions at which stalling losses set in for a range of combinations of thrust coefficient and tip-speed ratio.

Report presenting the effects of various catalysts used to cure resinous adhesives on the strength properties of plywood, especially in regard to the degree of solidity developed by the catalysts in the resin film and the plywood. Six resins were tested with birch wood, which is the most commonly used wood in aircraft construction.

Report presenting two-dimensional span-loading tests of a two-foot-chord NACA 65(sub 1)-012 airfoil model in the stability tunnel to determine tunnel-wall boundary-layer effects. Testing indicated that a small loss in average load may be expected. Results regarding tunnel-wall velocity profiles, pressure distributions, spanwise surveys, and force and moment coefficients are provided.

"The present report deals with the effect of turbulence on the propagation of the flame. Being based upon experiments with laminar as well as turbulent Bunsen flames, both the physico-chemical and the hydro-dynamical aspects of the problem are analyzed. A number of new deductions, interesting from the point of view of engine combustion and other very rapidly changing flame reactions, are made" (p. 1).

Report presenting a procedure for calculating pressure distributions over airfoils at supercritical Mach numbers. Only the forward portion of the airfoil, where interaction between local boundary-layer thickness and local-pressure distribution is negligible, is considered in detail. The method cannot be considered definitive because it requires that certain characteristics regarding pressure distributions and geometric properties be known.

Note presenting the thermal performance of an air-heated propeller, installed on a test airplane, as evaluated by observations of the ice-prevention properties of the propeller during flight in natural icing conditions and by the collection of thermal data on the propeller during flight in clear air and in clouds at temperatures above freezing. The results indicated that the air-heated-propeller installation tested would offer little or no protection to the leading-edge regions of the propeller during flight in severe natural-icing conditions.

Note presenting the thermal performance of an air-heated propeller, installed on a test airplane, as evaluated by observations of the ice-prevention properties of the propeller during flight in natural-icing conditions and by the collection of thermal data on the propeller during flight in clear air and in clouds at temperatures above freezing. The results indicated that the air-heated-propeller installation tested would offer little or no protection to the leading-edge regions of the propeller during flight in severe natural-icing conditions.

Note presenting photographic records of the behavior of a blade in flight as obtained with a conventional single-rotor helicopter. The results of the measurements of flapping motion, in-plane motion, and blade distortions are presented for selected conditions of flight at tip-speed ratios ranging from 0.12 to 0.25. Plots of blade twisting and blade bending in the plane of flapping are presented for a sample case.

Note presenting the results of glide performance tests conducted on a test helicopter with its original production blades in the autorotation condition. The data was reduced to coefficient form, and performance at standard sea-level conditions were calculated.

A calulation of the flow in turbine blading is reported that includes the calculation of effect of centrifugal force. Frictional losses on the stator blades and rotor blades are allowed.

This report records analyses on the fluorescence procedure of uranyl salts.

"It will be shown that by the use of the concept of similarity a simple representation of the characteristic curves of a compressor operating in combination with a turbine may be obtained with correct allowance for the effect of temperature. Furthermore, it becomes possible to simplify considerably the rather tedious investigations of the behavior of gas-turbine power plants under different operating conditions. Characteristic values will be derived for the most important elements of operating behavior of the power plant, which will be independent of the absolute values of pressure and temperature" (p. 1).

"After defining the aims and requirements to be set for a control system of gas-turbine power plants for aircraft, the report will deal with devices that prevent the quantity of fuel supplied per unit of time from exceeding the value permissible at a given moment. The general principles of the actuation of the adjustable parts of the power plant are also discussed" (p. 1).

Report presenting a metallurgical examination of the material used in the fabrication of a thermal ice-prevention system after 225 hours of actual flight operation of the heating installation. Only minor corrosion was noted and no impairment of tensile strength was observed.

Report issued by the Bureau of Mines on studies of coal deposits of the Coal Creek district. The physicality, geology, and characteristics of samples are listed. This report includes tables, and a map.

Note presenting an investigation of the laminar boundary layer and the position of the transition point on a heated flat plate. The Reynolds number of transition was found to decrease as the temperature of the plate is increased. Results regarding the effect of surface temperature, effect of roughness elements, mean-velocity profile near a heated wall, instability of inflection-point profiles, and laminar separation and transition are provided.

"A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented" (p. 1).

"This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values" (p. 1).

Research was undertaken to ascertain the properties of better wrought heat resisting alloys in the form of large discs required for gas turbine rotors. The properties of large discs of low carbon N-155 alloy in both the as-forged and water-quenched and aged conditions were determined by means of stress-rupture and creep tests for time periods up to about 2000 hours at 1200, 1350, and 1500 F. Short-time tensile test, impact test, and time-total deformation characteristics are included.

Report presenting a method for calculating wing characteristics by lifting-line theory using nonlinear section lift data. The wing characteristics calculated from general nonlinear section lift data have been found to agree much closer with experimental data in the region of maximum lift coefficient than those calculated on the assumption of linear section lift curves.

A general method for studying the flow of a compressible fluid around a closed body was discussed in Part I of this report. Here, application is made to the specific case in which the linearized equation of state is used. For a given incompressible flow around a specific profile, a corresponding compressible flow is found. The flow at infinity remains unchanged. Detailed studies are made of the flow with circulation around a unit circle, and velocity distributions are found for a wide range of Mach number and angle of attack. Comparisons are made with other methods.

Abstract: Exceedingly pure uranium tetrachloride was prepared for use in determining the physical constants of the compound. Measurements were obtained of the melting point and boiling point at pressures ranging from the triple point pressure to atmospheric pressure. Calculations were made of the vapor pressure equation for the liquid, the heat of evaporation, molar boiling point elevation, the vapor pressure equation for the solid, and the critical temperature.

As a means of preparing for high-altitude flight with spark-ignition engines in conjunction with exhaust-gas turbosuperchargers, various methods of modifying the exhaust-gas temperatures, which are initially higher than a turbine can withstand are mathematically compared. The thermodynamic results first obtained are then examined with respect to the effect on flight speed, climbing speed, ceiling, economy, and cruising range. The results are so presented in a generalized form that they may be applied to every appropriate type of aircraft design and a comparison with the supercharged engine without exhaust-gas turbine can be made.