Report presenting a flight investigation made of boundary-layer and profile-drag characteristics of smooth wing sections of a P-47D airplane. Measurements were made at three stations on the wing: boundary-layer measurements, pressure-distribution measurements, and wake surveys. The results indicated that a minimum profile-drag coefficient of 0.0062 for the smooth section at 63 percent semispan was obtained.

Report presenting a boundary-layer-transition and profile-drag investigation conducted on an experimental low-drag wing installed on a P-47 airplane designated the XP-47F. Measurements were made at a section outside the propeller slipstream with smooth and with standard camouflage surfaces and on the upper surface of a section in the propeller slipstream with the surface smoothed. Results regarding the right wing section outside the slipstream and left wing section in the propeller slipstream 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).

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.

"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 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 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.

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.

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.

Report presenting results of calibration in axial tension over the strain range 0 to 0.03 are presented for 15 types of single element, multistrand wire strain gages. Considerable nonlinearity was observed at strains between 0.0025 and 0.006. Fifty-eight percent of the gages failed by breaking of the strain-sensitive wire at strains less than 0.03.

Report presenting testing of the effect of applying a number of cycles of a high fatigue stress followed by a number of cycles of relatively low stress to failure has been investigated on 93 drilled specimens of a 24S-T sheet. The results indicated that any general formula for endurance must take sequence into consideration, which makes overly simple formulas inadequate to describe endurance over varying stress amplitudes.

Note presenting an investigation of the fatigue characteristics of riveted joints in aluminum alloy sheet. The purpose of this report is to summarize all the results of fatigue tests that have been made to date in the Aluminum Research Laboratories of lap joints with 1/8-inch aluminum alloy rivets.

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.

Note presenting an analysis of a procedure for artificially aging assemblies and subassemblies to improve the strength properties of the wrought aluminum alloys comprising their principal structure. Information is given on the magnesium alloys which may be present. The forms in which magnesium alloys may be encountered are casings, extrusions, forgings, and sheet.

Report presenting an investigation to determine the bearing yield and ultimate strengths of 75S-T alloy in sheet form in both with- and across-grain directions and extruded angle in the longitudinal direction. Ratios of bearing to tensile properties were also determined.

Note presenting tests on the use of x-ray diffraction methods for determining surface stress distributions in notched tensile bars and in the vicinity of a welded joint in aircraft steel tubing. Data on the effects of stress and degree of notching on the principal stresses and stress-concentration factors for flat notched tensile-test specimens were obtained.

From Introduction: "The investigations in this paper were made to obtain more generalized mathematical analyses of monocoque structure subjected to internal pressure. It is also assumed that the principle of superposition can be applied, so that stress analysis of a structure with combined internal pressure and external load can be made without excessive complication."

"Tests have previously been made to determine the column strength of magnesium alloy AM-C58S-T5 extruded rod, but these few data were not considered a satisfactorily wide basis for establishing a general formula for the column strength of this alloy. It was therefore decided to make additional tests on a number of extruded sections of magnesium alloy AM-C58S-T5 with some tests on AM-C58S for comparison" (p. 1).

Note presenting a study of the stress measurements by means of the x-ray diffraction method, which have found considerable application in solving both commercial and laboratory problems. Two problems related to x-ray diffraction are studied and a literature review is conducted.

Report presenting an investigation of various mechanical and physical properties of several expanded plastics and other low-density materials of interest for aircraft applications, such as heat insulation or the core of a sandwich material. The materials in the investigation included cellulose acetate plastic, polystyrene, a urea-formaldehyde resin, a zein product, hard rubber, balsa wood, and cellular glass.