Report presenting a solution for the problem of the compressive buckling of simply supported, flat, rectangular, Metalite type sandwich plates stressed either in the elastic or plastic range. Charts for the analysis of long sandwich plates are provided for plates with face materials of 24S-T3 aluminum alloy, 75S-T6 Alclad aluminum alloy, and stainless steel.

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.

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.

"A method developed in a previous report for finding the induced velocity field behind a supersonic wing with known load distribution is used to find the downwash behind a triangular wing with subsonic leading edges. Results are given for the chord plane in the extended vortex wake of the wing and for the vertical plane of symmetry up to about 20 percent of the wing span above the plane of the wing" (p. 1).

Note presenting a theory of plasticity based on the concept of slip as proposed for the relationship between stress and strain for initially isotropic materials in the strain-hardening range. The theory is an extension to polyaxial stress conditions of the conventional uniaxial stress-strain relation, and time-dependent effects, such as creep and stress relaxation, are not considered.

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.

"A theoretical solution is presented for the critical axial-compressive stress of a simply supported curved rectangular panel having a central longitudinal stiffener offering no torsional restraint. The results are presented in the form of computed curves and tables. Because a panel of moderate or large curvature buckles in compression at a stress lower than the theoretical value, a method is suggested to aid in determining the critical stress for use in design" (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.

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 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.

Note presenting thermodynamic properties of the products of combustion of five different mixtures of air with typical aircraft-engine fuel, which have been calculated from the most reliable thermodynamic data available. The calculations are presented in five charts of internal energy plotted against entropy with values of temperature, specific volume, pressure, and enthalpy indicated corresponding to five different percentages of the fuel-air ratio for perfect combustion.

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.

Report presenting a theoretical solution for the buckling of Alclad plates on the basis of plasticity theory. Both the differential equation of equilibrium of the buckled plate and energy expression are provided. Results regarding the buckling of long simply supported plates under longitudinal compression and under shear and for a plate column are provided.

Report presenting the condition for plastic buckling of a long flat plate under combined shear and longitudinal compression is obtained by using the theory of plastic buckling developed for simple loading, provided the ratio of shear to longitudinal compression is assumed constant during the loading process. A detailed calculation for a number of simply supported plates made of a typical aluminum alloy shows that an approximate algebraic relationship provided in the paper will suffice for determination of buckling stress.

Report presenting testing to determine the force developed in a shock strut as a function of the flexibility of the attached wing structure. Both the experiment and analysis indicated that wing flexibility had some effect on the shape and peak value of the force-time curve in a shock strut.

Note presenting an investigation to derive the implications of a previously derived equation for rotating beams.

"Available information on gust structure, airplane reactions, and pertinent operating statistics has been examined. This paper attempts to coordinate this information with reference to the prediction of gust loads on airplanes. The material covered represents research up to October 1947" (p. 1).

Meteorological conditions conducive to aircraft icing are arranged in four classifications: three are associated with cloud structure and the fourth with freezing rain. The range of possible meteorological factors for each classification is discussed and specific values recommended for consideration in the design of ice-prevention equipment for aircraft are selected and tabulated. The values selected are based upon a study of the available observational data and theoretical considerations where observations are lacking. Recommendations for future research in the field are presented.

Measurements have been made of the mean total-head and temperature fields in a round turbulent jet with various initial temperatures. The results show that the jet spreads more rapidly as its density becomes lower than that of the receiving medium, even when the difference is not sufficiently great to cause measurable deviations from the constant-density, dimensionless, dynamic-pressure profile function. Rough analytical considerations have given the same relative spread. The effective "turbulent Prandtl number" for a section of the fully developed jet was found to be equal to the true (laminar) Prandtl number within the accuracy of measurement. (author).

Report presenting an investigation to determine the opening characteristics of several hemispherical parachutes at airspeeds up to 200 miles per hour and to study the influence of the parachute design variables on the opening characteristics. The effects of design variables on the drag and stability characteristics of the parachutes were also evaluated.

Report presenting the theory for calculating the free-space oscillating pressures associated with a rotating propeller at any point in space. Good agreement was found between analytical and experimental results using this method. Results regarding vibration and sound levels in the fuselage in relation to pressure level are reported.

From Introduction: "Although the aerodynamic characteristics of the components of such configurations may be well known, the mutual interference resulting from combining the wings, as well as the wings and body, may be so great that is desirable to study the aerodynamic properties of the complete configurations. Two methods of handling this problem are presented in this report. The first method is essentially an extension of the theory for slender wing-body combinations of reference 1 to determine the load distribution, forces, and moments exerted on slender cruciform-wing and body combinations inclined simultaneously at small angles in pitch and yaw. "

From Summary: "The purpose of this investigation was to determine whether such airplanes could be made to fly uncontrolled for an indefinite period of time without getting into dangerous attitudes and for a reasonable period of time (one to three minutes) without deviating excessively from their original course. The results of this analysis indicated that the uncontrolled motions of a personal airplane could be made safe as regards spiral tendencies and could be greatly improved as regards maintenance of course without resort to an autopilot."

Note presenting a theoretical solution for the problem of the compressive buckling of flat rectangular Metalite type sandwich plates with simply supported loaded edges and clamped unloaded edges. The solution is based on the general small-deflection theory for flat sandwich plates developed in a previous report. Results regarding stability orientation and buckling curves, comparison with approximate solution, correction for plasticity, and comparison of theory and experiment are provided.