"Low-aspect-ratio wings having pointed plan forms are treated on the assumption that the flow potentials in planes at right angles to the long axis of the airfoils are similar to the corresponding two-dimensional potentials. For the limiting case of small angles of attack and low aspect ratios the theory brings out the following significant properties: (1) The lift of a slender, pointed airfoil moving in the direction of its long axis depends on the increase in width of the sections in a downstream direction. Sections behind the section of maximum width develop no lift. (2) The spanwise loading of such an airfoil is independent of the plan form and approaches the distribution giving a minimum induced drag. (3) The lift distribution of a pointed airfoil travelling point-foremost is relatively unaffected by the compressibility of the air below or above the speed of sound. A best of a triangular airfoil at a Mach number of 1.75 verified the theoretical values of lift and center of pressure" (p. 1).

Report presenting a number of tests on the effect of service stresses on impact resistance, X-ray diffraction patterns, and the microstructure of the 25S aluminum alloy.

From Summary: "An analysis of available theory on seaplane impact and a proposed modification thereto are presented."

Note presenting an instrument that measures small absolute humidity changes by photoelectric examination of the 9440 angstrom units absorption band of water vapor. The instrument consists of a small source of light which sends its radiation over an air path of less than 1.5 meters to a dispersing system.

Report presenting a series of tests to determine the bearing yield and ultimate strengths of samples of 1/4- and 2-inch-thick plate of aluminum alloy 24S-T and to establish nominal ratios of bearing-to-tensile properties for the commercial range of plate thicknesses. Results regarding individual bearing testing, ratios of average bearing to tensile properties, and ratios of bearing yield strength to tensile yield strength are provided.

"For a simple diffraction pattern, the time required to calculate interplanar distances from measurements of the pattern is not excessive. If more than a few lines are present, however, or if several patterns are to be studied, it is very advantageous to have available a table giving interplanar spacings directly in terms of the linear measurements made on the film of the lines appearing on the diffraction pattern. The preparation of the table given here was undertaken when the expansion of research activities involving X-ray diffraction techniques indicated that such a table would greatly decrease the time required to analyze diffraction patterns" (p. 1).

"Stress concentration factors for shear stresses around cut-outs in the webs of beams having shear resistant webs were determined by the photoelastic method. Webs with circular, square, and rectangular cut-outs were tested. The effect of reinforcements around square and circular cut-outs was investigated" (p. 1).

Note presenting measurements of heat flow to air at subsonic velocities and substantially constant Reynolds number, which show that the heat-transfer coefficient is independent of the difference between the temperature of the heated wall and the adiabatic wall temperature. Recovery factors are measured at the pipe wall for adiabatic flow.

"The present report covers tests made on elliptical cylinders with a center support which were subjected to various simple and combined loadings. The tests yielded a series of interaction curves for combined loadings on such cylinders which should be useful in wing nose section analysis" (p. 1).

Note presenting a two part report on cylinder; one is on the modulus of electricity of celluloid sheet and the effect of temperature change on the value of the modulus of elasticity, while the other gives the results of tests on a considerable number of thin-walled, circular celluloid cylinders of several lengths, diameters, and wall thicknesses.

Note presenting an experimental determination of the apparent friction coefficient for the flow of air through smooth pipes at subsonic and supersonic velocities. In supersonic flow, the results were found to be strongly influenced by the presence of oblique shocks formed at the junction of nozzle and pipe. Results regarding the apparent friction coefficient, subsonic flow, supersonic flow, and comparisons with other investigations are provided.

Note presenting the necessary pressure and force coefficients acting on a thin airfoil with a flap and tab in a form suitable for stability calculations in order to design improved control arrangements.

Note presenting a determination of the bonding strengths of two thermosetting adhesives, liquid Cycleweld C-3 and Ardux 1, to several aircraft materials using shear tests made on lap-joint specimens. The specimens were tested at 25 degrees Celsius and at subfreezing temperatures of approximately -40 degrees Celsius. Results regarding the specimens bonded under clamping pressure, specimens bonded after various surface treatments, specimens of metal bonded to plywood, and specimens of aluminum bonded to magnesium are provided.

Note presenting an experimental investigation of the influences of blade shank form and pitch distribution on the aerodynamic characteristics of constant-speed propellers. The results indicated that the replacement of round blade shanks by faired ones produced substantial improvements of efficiency which increased with the advance ratio. Results regarding blade shank form, pitch distribution, and influences of blade loading and number of blades are provided.

Report presenting the third part of an investigation dealing with the inward bulge type buckling of monocoque cylinders the theory of buckling in pure bending, which is refined through the consideration of the shear strain energy stored in the sheet covering, the assumption of a revised deflected shape of the rings, and the use of summations in place of some of the integrations of the preceding report.

Note showing that under certain conditions, a two-dimensional subsonic compressible flow around an airfoil profile can be derived from an incompressible flow around another profile. The connection between the two "conjugate flows" is given by a simple conformal transformation of the respective hodograph planes.

"This report is devoted to the study of two-dimensional steady motion of a compressible fluid. It is shown that the complete flow pattern around a closed obstacle cannot be obtained by the method of Chaplygin. In order to overcome this difficulty, a formula for the stream-function of a two-dimensional subsonic flow is derived" (p. 1).

Note presenting a study of the shear elastic properties of monel, nickel, Inconel, and aluminum-model tubing, as influenced by extension of annealed specimens, by cold reduction during manufacture, and by stress-relief annealing of cold-reduced materials. With slight extension of annealed tubing, the shear proof stresses generally decrease, owing to induced internal stress.

"The circulatory subsonic flow around an infinite circular cylinder is computed using the linearized pressure-volume relation, by a method developed in a previous report. Formulas and graphs are given for the velocity and pressure distributions, the circulation, the lift, and the dependence of the critical Mach number upon the position of the stagnation point" (p. 1).

"There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions" (p. 1).

"Chaplygin introduced the hodograph method in the theory of compressible fluid flows and developed a method for constructing stream functions of such flows. This method, which has been extensively used in investigation of compressible fluid flows, is limited in certain respects. The expression for the stream function obtained in this manner can represent only certain types of flow patterns. In general, flow patterns obtained in this way cannot represent the whole flow around an obstacle, but only a part of such a flow, and therefore several expressions are needed in order to obtain the whole flow" (p. 1).

Note presenting wing beams tested under axial compressive loads, transverse loads, and combined axial and transverse loads. Deflections and strains in the elastic range were in general agreement with those computed from the simple beam theory after taking account of the secondary bending moment produced by the axial load as the beam deflected under load.

Report presenting an investigation regarding the strengths of bonds between different chemical types of adhesives and adherends. Some of the topics explored include the theoretical aspects of adhesion and properties of adhesively bonded structures.

"Experimental data on the heats of combustion and hydrogen contents of a number of aviation gasolines have been used in deriving a formula for computing net heat of combustion from (measured) gross heat of combustion. This formula appears to be sufficiently reliable for the purpose and has the advantage of making hydrogen determinations unnecessary. The data on heats of combustion are presented in tabular form, and in graphs showing the relation between net heat of combustion and (1) hydrogen content, (2) aniline point, (3) APO gravity, and (4) the product of aniline point and APO gravity" (p. 1).