Report presenting comparisons of the structural efficiency of panels with straight-web and curved-web Y-section stiffeners. In the high-stress region in which failure is at least in part associated with local buckling, panels with curved-web Y-section stiffeners have higher structural efficiencies than panels with straight-web Y-section stiffeners, which is evidenced by higher average stresses at failure, smaller stiffener heights, or wider average spacing of rivet lines.

"Direct-reading design charts are presented for 24S-T aluminum-alloy flat compression panels having longitudinal formed Z-section stiffeners. These charts make possible the direct determination of the stress and all the panel proportions required to carry a given intensity of loading with a given skin thickness and effective length of panel" (p. 1).

"Direct-reading design charts are presented for 24S-T aluminum-alloy flat compression panels having longitudinal straight-web Y-section stiffeners. These charts make possible the direct determination of the stress and all the panel proportions required to carry a given intensity of loading with a given skin thickness and effective length of panel" (p. 1).

Note presenting a prismatic-float forebody with an angle of dead rise of 40 degrees that was subjected to smooth-water impacts in the impact basin. The tests were made at fixed trims of 3, 6, 9, and 12 degrees for a range of flightpath angles from approximate 2 to 22 degrees. The data are presented and converted into dimensionless variables for correlation of the experimental results with hydrodynamic impact theory and for comparison of the runs among themselves.

"A method has been developed for evaluating from shadow or schileren photographs the pressure drag of axially symmetrical bodies at zero angle of attack or of two-dimensional bodies producing detached shock. The method consists in the determination of the flow properties along a characteristic line and the application of the momentum theorem to a stream tube around the body. The method can be applied to the determination of external drag of supersonic inlets with subsonic flow at the entrance of the inlet" (p. 1).

Note presenting the use of the method of characteristics for the determination of the supersonic-flow properties around bodies of revolution at a small angle of attack. The system developed considers the effect of the variation of entropy due to the curved shock and determines a flow that exactly satisfies the boundary conditions in the limits of the simplifications assumed.

Note presenting a wind-tunnel investigation made of the lateral-control characteristics of a thin, low-drag, semispan wing equipped with three configurations of circular plug ailerons and a full-span, 25-percent-chord, slotted flap. The investigation was performed through a Mach number range of 0.13 to 0.61. Results regarding wing aerodynamic characteristics, aileron control characteristics, comparison of lateral-control characteristics of the three configurations of circular plug aileron, comparison of lateral-control characteristics of the circular plug ailerons, a conventional plug aileron, and a retractable aileron, and a comparison of lateral-control characteristics of the circular plug ailerons with those of a sealed plain aileron are provided.

Report presenting a wind-tunnel investigation at low Mach and Reynolds numbers to determine the high-lift and lateral control characteristics of a semispan wing of NACA 65(sub 2)-215 airfoil section equipped with a 25-percent-chord, full-span, slotted flap and plug and retractable ailerons. The ailerons were located at the 70-percent-chord station over the outer 49 percent of the wing semispan and were fabricated in five spanwise segments. Results regarding the wing aerodynamic characteristics, lateral control characteristics, comparison of lateral control characteristics of the plug and retractable ailerons, and a comparison of lateral control characteristics of the plug and retractable ailerons on the present wing with similar ailerons on an NACA 65-210 wing are provided.

Note presenting the properties of large forged discs of S-590 alloy at room temperature, 1200, 1350, and 1500 degrees Fahrenheit in order to determine the level of properties obtainable in forgings of the type required for the rotor discs of gas turbines. The high physical properties of the forged and aged disc at temperatures up to 130 degrees Fahrenheit were its outstanding characteristics. Results regarding the hardness survey, short-time tensile properties, Charpy impact resistance, rupture test characteristics, time-deformation characteristics, creep strengths, and stability characteristics are provided.

Report presenting calculations of the longitudinal stability characteristics of elastic swept wings of high aspect ratio experiencing bending and torsional deformations by applying the linearized lifting-surface theory. Results of numerical calculations for a wing of aspect ratio 3.2 and 60 degrees of sweepback at Mach number 1.414 are provided. A discussion of the supersonic lifting-surface theory, comparison of aeroelastic effects at supersonic speed with incompressible flow solutions, and strip theory are also provided.

Report presenting an investigation of seven hot-pressed ceramics for possible gas-turbine application. The properties, short-time tensile strength, thermal-shock resistance, coefficient of liner expansion, and density were determined. The ceramics tested were magnesium oxide, titanium carbide, zirconium carbide, boron carbide, silicon carbide with boron carbide, zircon, and zirconia with lime.

Report presenting a wind-tunnel investigation to determine the boundary-layer and stalling characteristics of the NACA 63-009 airfoil section. Pressure distributions, tuft studies, and boundary-layer measurements were obtained. A localized region of flow separation was found to develop on the upper surface of the airfoil near the leading edge.

"In order to provide engineers interested in rotating-wing aircraft but with no specialized training in stability theory some understanding of the factors that influence the flying qualities of the helicopter, an explanation is made of both the static stability and the stick-fixed oscillation in hovering and forward flight in terms of fundamental physical qualities. Three significant stability factors - static stability with angle of attack, static stability with speed, and damping due to a pitching or rolling velocity - are explained in detail" (p. 1).

Note presenting an investigation of the use of measured static pressures in a vaneless-diffuser passage for determining centrifugal-compressor performance. The general effects of diffuser-wall-surface friction were studied to locate the regions in the vaneless-diffuser passage where the most valid evaluation can be made by the static-pressure method.

Note presenting an investigation conducted to determine the oxidation characteristics of molybdenum disulfide and to determine the effect of such oxidation on its role as a solid-film lubricant. A coating of molybdenum disulfide serving as a high-temperature solid-film lubricant maintained low coefficient-of-friction values during its oxidation as long as an effective subfilm of the molybdenum disulfide remained.

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.

Report presenting a wind-tunnel investigation conducted in rolling flow to determine the effects of aspect ratio and sweep on the rolling stability derivatives for a series of untapered wings. The results indicated that when the aspect ratio is held constant, an increase in sweepback angle causes a significant reduction in the damping in roll at low lift coefficients for only the higher aspect ratios tested.

Note presenting the compressive buckling stress of outstanding flanges reinforced by bulbs, which was computed by the strain-energy method for flanges with 10 shapes and a range of lengths. The results were checked for some cases by computations based on a differential-equation method. The results were analyzed to determine which shape of flange gave the greatest support to the structure to which it was attached.

From Summary: "In order to facilitate the application of miscellaneous airfoil data to the problems of the helicopter designer, a discussion of a number of the problems most frequently arising is presented. A reference list of published papers on airfoil section characteristics (or their application) which experience has shown to be useful in connection with these helicopter problems is included."

Report presenting flight-test measurements and corresponding pilot's opinions of the forward-flight longitudinal flying qualities characteristics of several single-rotor helicopters. The most important consideration for satisfactory characteristics appears to be the prevention of prolonged stick-fixed divergent tendencies. Results regarding the characteristics appreciated, theoretical analysis of pull-up characteristics, and practical requirements are provided.

Report presenting an investigation of pitching moments and center-of-pressure locations obtained from a landing investigation in smooth water of a conventional flying boat as compared to values predicted by general hydrodynamic impact theory. Landings were generally moderate and covered as wide a range of trim and velocities as practical. Results regarding the center of pressure and pitching moments are provided.

Note presenting an investigation of a two-blade and a three-blade propeller on a slender-nose fighter airplane in climb and at high speed.

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.

Report presenting the partial differential equation for the perturbation velocity potential, which is examined for free-stream Mach numbers close to and equal to one. Under the assumptions of linearized theory, solutions can be found consistent with the theory for lifting-surface problems in stationary three-dimensional flow and in unsteady two-dimensional flow.