Note presenting an analysis that was undertaken as part of an investigation of low-density fibrous core materials for sandwich construction. This particular investigation found that honeycomb structure exhibit promise as core materials because of their high strength-weight ratios. A formula has been derived that considerably reduced the amount of testing necessary to evaluate the effectiveness of the materials.

From Introduction: "An investigation was made to determine the relative significance of the factors that affect the exhaust process; the effects that an exhaust-process change has on cylinder charging were given special attention. Differential equations of this nature have been developed by Kemble (reference 1) but the forms of these equations are such that general conclusions regarding the various factors affecting the exhaust process cannot be determined."

The feasibility of measuring the vibration in the buckets of a gas turbine under service conditions of speed and temperature was determined by use of a high temperature wire strain gauge cemented to a modified supercharger turbine bucket. A high-temperature wire strain gauge and the auxiliary mechanical and electrical equipment developed for the investigation are described.

"In conjunction with assumptions concerning the proportion of time spent at various speeds, statistical gust data were used to determine gust load factors that could be exceeded a given number of times during the operational life of an airplane. The results indicated that present gust load factors might be considerably lowered in certain cases with a consequent decrease in structural weight. Modification of the present criterion, however, must await the accumulation of data not presently available" (p. 1).

From Summary: "Previous tests of blower-blade sections have been extended by a series of tests at 52.5 degrees stagger. The results of these tests have been combined with the earlier test results and are presented in new blade design charts which supersede those previously presented. An investigation in a test blower over a range of stagger from 44 degrees to 65 degrees has shown that for blades at a solidity of 1.0, the two-dimensional cascade data predict the turning angle to within 1/2 degrees."

Report presenting an analysis of wind-tunnel data on the hinge-moment characteristics of control-surface tabs. Results regarding the correlation of section data, correlation of finite-span data, and effect of Mach number are provided.

Report presenting a comparison of the maximum amount of transverse righting moment at rest provided by auxiliary floats or stub wings for 25 seaplanes and the minimum righting moment required by certain design specifications. Large differences were found to exist between the specifications and 25 designs studied.

Report presenting comparisons of 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners and panels with flat FS-1E magnesium-alloy sheet and longitudinal 24S-T aluminum-alloy Z-section stiffeners. The use of the composite magnesium-alloy, aluminum-alloy construction permits wider stiffener spacing with little to not loss in structural efficiency or stress for local buckling. Results regarding stiffener spacing, proportions, and consideration of the different material constructions are provided.

Report presenting drag tests conducted on a practical-construction airfoil section. The tests consisted of drag measurements over a wide range of Reynolds number and over a small range of section lift coefficient for the model with various surface conditions. Results regarding waviness characteristics and drag characteristics are provided.

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.

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.

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.

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.

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.

Report presenting expressions for calculating the sideslip angles in certain maneuvers and numerical solutions for a wide enough range of variables to permit construction of design charts. Results regarding a comparison of flight and theoretical data and vertical-tail loads are provided.

Report presenting a paper in two parts about transition and turbulent boundary layers. The first part reviews the current problem of the instability of laminar boundary layers. The second part reviews the current state of knowledge of the mechanics of turbulent boundary layers and of the methods now being used for fundamental studies of the turbulent fluctuations in turbulent boundary layers.