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.

Note presenting compressive-strength data on flat plates for a number of aircraft structural materials subjected to graphical study. Results indicated that the maximum average stress, in the region where it differs appreciably from the critical stress, could be expressed as a constant times the one-fourth power of the critical stress times the three-fourths power of the compressive yield stresses.

Note presenting the results of a series of investigations conducted by various laboratories which has led to a nomenclature with definitions of various turbine parameters and a consistent set of physical constants.

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 a comparison of the thermal performance and pressure-drop characteristics of heat exchangers on a heat-exchanger test stand. The exchangers included parallel and cross-flow units as well as extended-surface and all-prime-surface units.

Report presenting some methods for the systematic design of group displacements which expedite the liquidation of residuals in certain classes of problem, and the application of these methods is illustrated by numerical examples. Tables of functions are available to use with this method, which leads to much faster and easier computation.

Note presenting a theory that has been developed for the calculation of the mass of fluid pumped per stroke and of indicator diagrams for the pumping process of internal-combustion engines, compressors, or vacuum pumps. The theory enables the volumetric efficiency and indicator diagrams for the inlet and exhaust processes of an internal-combustion engine to be obtained even before the engine is actually built. It is also possible to calculate some hypothetical inlet and exhaust processes which are impossible to obtain on actual engines, such as the cases where the valves open and close instantaneously.

Note presenting an experimental investigation conducted to determine the orifice coefficient of a jet directed perpendicularly to an air stream as a function of pressure ratio and jet Reynolds number for circular, square, and elliptical orifices. The effect of air-stream velocity on the jet flow was also determined for three tunnel-air velocities. Results regarding jets discharging into still air and effect of tunnel-air velocity on jet flow.

"A method of modifying existing correction factors of lifting-surface theory to account approximately for the effects of sweep was derived, and these factors were applied to existing lifting-line theories for the lift and damping in roll of swept wings. Despite the simplicity of the resulting formulas the agreement with experimental data for low speeds is very good. The equation for lift is expressed entirely in terms of the geometric characteristics of the wing and the section-lift-curve; the necessity for any charts is thereby eliminated" (p. 1).

Note presenting meteorological data from flight observations in icing conditions during the first 5 months of 1948. A total of 335 measurements of liquid-water content and mean-effective drop diameter were obtained by the multicylinder method in the course of 40 flights in icing conditions covering most of the northern United States. Information regarding the discontinuous character of icing clouds, variation of average liquid-water content with extent of icing conditions, and variation of drop diameter from year to year and with geographic location are provided.

Note presenting a low-turbulence wind tunnel investigation of an NACA 64A010 airfoil with a porous surface of sintered bronze to determine the reduction in section drag coefficient that might be obtained at large Reynolds numbers by use of suction to produce continuous inflow through the surface of the model. Results regarding the uncompartmented model, compartmented model, observations on stability of laminar boundary layer, and theoretical calculations are provided.

Report presenting an investigation in the two-dimensional low-turbulence pressure tunnel to determine the aerodynamic characteristics of the NACA 8-H-12 airfoil section at four Reynolds numbers. The section lift, drag, and pitching-moment characteristics are presented for smooth and rough surface conditions. Generally, no unusual scale effects are present for either condition.

Report presenting a study of the factors involved in the design of total-temperature probes for use at supersonic speeds as applied to the design of an instrument to be used in wind-tunnel calibrations. Tests of the probe showed that the calibration factor required in the conversion of the measured temperature to the true total temperature was 0.992 for a range of Mach numbers.