Report presenting direct-reading design charts for 24S-T3 aluminum-alloy flat compression panels with longitudinal formed hat-section stiffeners. The charts make it possible to directly determine the stress and all panel proportions required to carry a given intensity of loading with a given skin thickness and effective length of panel. Results regarding simple compression, combined compression and bending, and combined compression, bending, and shear are provided.

Report presenting the results of calibrations to determine axial and transverse strain sensitivities for 15 types of single-element, multistrand wire strain gages. The gages were separated into those which had positive average ratios of transverse sensitivity and those which had negative transverse sensitivity.

Report presenting testing on 31 airfoils to determine the effects of thickness, trailing-edge bluntness, boattailing, and forward profile on the aerodynamic characteristics of thin airfoils, and to provide a check on available theoretical methods. The airfoils were 2, 4, and 6 percent thick and were tested at two Mach numbers at three Reynolds number in clean condition and one with transition fixed.

Note presenting tables of thermal properties of molecular nitrogen that have been prepared in an NBS-NACA series and grouped together for convenient use. Some of the properties include the thermodynamic functions for the gas, both real and ideal, the transport properties for the gas, and the vapor pressure of the liquid and the solid.

Report presenting a set of tables which aids in the numerical determination of the Fourier transform of a function of time and the inverse Fourier transform of a function of frequency. Many of the operations normally performed theoretically with the operational calculus can be performed numerically with the aid of the tables. Some applications using the tables are described.

Report presenting combined force and wake survey tests on three-blade model propellers in order to determine the effects of blade-width distribution on constant-speed efficiency characteristics. The most important result is the demonstration that blade-width distribution has a marked influence on the constant-speed efficiency characteristics of propellers.

"A tabulation is presented of functions of the Mach number which are frequently used in high-speed aerodynamics. The tables include values of Mach number from 0 to 10.0 in increments of 0.01 and the functions are based on the assumption that air is a perfect gas having a specific-heat ratio of 1.400" (p. 1).

"Tests were carried out in the small wind tunnel of the Gottingen establishment on a complete model of the AEG D I airplane. The agreement between the model and the complete airplane applies particularly to the wings, which have ribs cut out of sheet metal and built up in exactly the same manner as in the actual airplane. Various series of tests were carried out with this model in which one or the other of the control surfaces were adjusted to various angles, while the others remained in their neutral positions" (p. 1).

"Direct-reading design charts are presented for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners. These charts, which cover a wide range of proportions, make possible the direct determination of the stress and all panel dimensions required to carry a given intensity of loading with a given skin thickness and effective length of panel" (p. 1).

Note presenting results of mechanical tests of several laminated plastics, including canvas laminate molded at low pressure, grade-C canvas laminate, rayon laminate, paper laminate, and glass-fabric laminate. The following tests were performed: static tension, compression, and torsion tests; long-time creep tests at different stresses on specimens loaded in tension; fatigue tests of unnotched specimens in bending; fatigue tests of notched specimens in bending; fatigue tests in bending at temperatures of -75, 77, and 160 degrees Fahrenheit; and fatigue tests in torsion.

Note presenting a study of the hydrodynamic characteristics obtained for a planing surface with a basic angle of dead rise of 20 degrees at the keel and horizontal chine flare. The wetted lengths, resistances, center-of-pressure locations, and drafts were determined at a range of speed coefficients, with the majority of the data obtained at Froude numbers in excess of 7.0.

Report presenting tables of thermodynamic functions for 42 substances containing argon, aluminum, boron, carbon, chlorine, fluorine, hydrogen, lithium, nitrogen, and oxygen. The functions examined included the specific heat at constant pressure, sensible enthalpy, sum of sensible enthalpy and chemical energy, molar entropy, enthalpy change due to formation of substance from elements in atomic gas state divided by gas constant times temperature, and the logarithm of the equilibrium constant at designated temperatures.

Report presenting the results of calibrations in axial compression over the strain range 0 to 0.0021 for 15 types of single element multistrand wire strain gages. The majority of gages showed significant differences between the calibration factors for strain increasing and strain decreasing. The majority of the gages were found to have slightly lower factors in compression than in tension.

Report presenting tables for determining the total-absorption coefficients as well was the intensities and spectral distribution of gamma rays at any scattering angle. Both experimental and computed data on gamma rays of quantum energies up to 20 million electron volts for all elements which have significant data available are provided. The accuracy of results is obtained by the use of tables.

Report presenting over 1000 measured convective heat-transfer coefficients for normal cylinders in subsonic slip flow that have been correlated by using Nusselt number as a function of Reynolds and Knudsen (or Mach) numbers. A complicated nonlinear dependence of the heat-transfer coefficient to the difference between cylinder and recovery temperature is reported. The application of these results to hot-wire anemometry is also discussed.

Report presenting force, moment, pressure-distribution, and boundary-layer measurements for a series of five airfoil sections. The stalling characteristics of the three airfoil sections at low speeds can be separated into three types. A deeper discussion of the role of boundary-layer flow and separation processes in relation to stalling and the sensitivity of stall to factors that influence boundary-layer growth is provided.

Report presenting testing of three-blade, adjustable-pitch counterrotating tandem model propellers adjusted to absorb equal power at maximum efficiency of the combination. The aerodynamic characteristics were determined for a variety of blade-angle settings and diameter spacings. At maximum efficiency, the tandem propellers absorb about double the power of the three-blade propellers and about 8 percent more power than six-blade propellers with the pitch of the forward propeller of the tandem combination.

Note presenting the results of an investigation made to obtain the wetted areas, three components of planing forces, and the three components of moments acting on a 0 degree and a 20 degree dead-rise surface in high-speed, unsymmetrical planing conditions. The collected test data are presented in summary plots which are readily applicable for use in determining the lift, drag, side force, pitching moment, rolling moment, and yawing moment.

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.

Note presenting a method for solving problems associated with Laplace and Poisson equations which, in general, requires considerably fewer equations than the usual methods and which gives a convergent solution by the method of successive approximations.

"The problem of the distribution of normal stress across a wide corrugated sheet used as the chord of a box-beam-like structure is investigated theoretically and experimentally. Expressions are developed giving the stress distribution in beams, symmetrical or unsymmetrical, about a plane passed spanwise through the center of the sheet. The experiments were arranged to insure bending without torsion and surveys of the normal stresses were made by means of mechanical and electrical strain gages" (p. 1).

Report presenting a two-dimensional low-speed investigation of four thin, cambered airfoil sections. The data included measurements of lift, drag, pitching moment, and chordwise distribution of pressure. The maximum lift section coefficients, stall, effect of Reynolds number on maximum lift, surface roughness, and increment of maximum lift by a simulated split flap are described in detail.

In order to determine an approximate formula giving the weight of a dead load as a function of the volume (V) of the envelope and of the maximum velocity (v), we will take the relative weight of the various parts of the airship (P(sub v), M, V, A, T(sup 34)), adopting a mean value of the coefficients determined. This formula may be adopted both for semi-rigid airships with suspended nacelle and non-rigid envelope, with or without internal suspensions. It may also be adapted to airships with rigid longitudinal beam, with power units on external supports or in nacelles, and with non-rigid envelopes, with or without internal bracing cables.

Report presenting some information on flow characteristics - velocity field, pressure drop, and friction - for steady, fully developed laminar flow through a duct consisting of two parallel walls, for flow throguh tubes with circular cross section, and for boundary-layer flow over infinite wedges. In order to determine the extent to which the boundary conditions imposed o the flow by the various geometries influence the flow characteristics, dimensionless parameters common to both channel and boundary-layer flow were developed.