Note presenting an investigation to determine the spot-welding characteristics of heavy gages of Alclad 24S-T aluminum alloy. The weldability of the alloy in thicknesses of 0.064, 0.081, and 0.102 inch was investigated in order to determine the capacity of the machine.

Report presenting the application of three methods for calculating span load distribution for five swept wings. The methods were examined to establish their relative accuracy and ease of application. While the Weissinger and Falkner methods were more useful for certain circumstances, there were no advantages noted with the Mutterperl method.

Note presenting results of tests on duplicate longitudinal and transverse specimens of Alclad aluminum-alloy 75S-T sheets with three nominal thicknesses. The stress-strain, stress-deviation, tangent-modulus, and reduced-modulus graphs are plotted on a dimensionless basis to make them applicable to material with yield strengths which differ from those of the test specimens.

Note presenting an investigation to determine the effect of preheating and postheating cycles on the quality and strength of spot welds in aluminum alloys. The results showed that the combination of a slowly rising condenser-discharge preheat current with a rapidly rising welding current afforded no more freedom from expulsion than was obtained with the rapidly rising welding current alone.

"The engineering theory of incomplete diagonal tension in plane webs presented in NACA TN No. 1364 is generalized in order to make it applicable to curved webs. Comparisons are given between calculated and experimental results for a number of stiffened cylinders subjected to torsional loads. Results regarding the test specimens, test procedure, results of strain measurements, ultimate strength of sheet, and ultimate strength of stringers" (p. 1).

"A method, based on the elastic theory for plate buckling and test results for 24S-T aluminum-alloy Z-stiffened panels, is shown for calculating the compressive strength of Z-stiffened panels that develop local instability. This method can be used to calculate the critical compressive stress above, as well as within, the elastic range. For stresses above three-fourths the compressive yield stress the method can be used for the approximate determination of the average compressive stress at maximum load" (p. 1).

Report presenting a method for calculating the upwash-velocity component in the vicinity of thin wings at supersonic speeds. The method is applied to obtain an expression for the upwash over wing tips of fairly general plan form and profile.

Note presenting the use of linear theory for determining the pressure distribution at supersonic speeds on wings of symmetrical section at zero lift to calculate the pressure drag coefficients at zero lift of the family of unswept, untwisted wings with the diamond profile. A general expression has been found for the drag coefficient at any supersonic Mach number, aspect ratio, and taper. It is too unwieldy for use in analysis, but it has been used in the construction of nondimensional charts permitting a rapid estimation of the drag coefficient for a given wing at any Mach number.

Note presenting an investigation to compare the crystal structure of the predominant phase at temperatures of 1200, 1500, and 1800 degrees Fahrenheit in 10 wrought heat-resisting alloys with crystal structure observed at room temperature. The alloys investigated included S-816, S-590, Hastelloy B, 19-9 W-Mo, N-155, 16-25-6, K-42-B, Inconel X, Nimonic 80, and type 347 stainless steel.

Report presenting an investigation of the effect of diffuser performance of the passage curvature of two vaneless diffusers designed with a 6 degree equivalent-cone divergence angle along a logarithmic-spiral path in combination with two mixed-flow impellers. The peak of overall adiabatic efficiency is compared with the corresponding diffuser efficiency. Results regarding the variation of diffuser efficiency with load-coefficient parameter and peak overall adiabatic efficiencies and corresponding diffuser efficiencies of the two compressors are provided.

Report presenting a high-speed wind-tunnel investigation of the aerodynamic characteristics at various Mach numbers of an NACA 65-210 semispan wing equipped with a 25-percent-chord full span slotted flap and a 38-percent-semispan 20-percent-chord straight-sided aileron. With the full-span flap retracted at a Mach number of 0.13, a maximum lift coefficient of 0.93 was obtained, and with the flap deflected 45 degrees, a maximum lift coefficient of 1.87 was obtained.

Report presenting an investigation conducted to determine the effect on the performance of a two-valve air-cooled aircraft cylinder of increasing the valve overlap from the conventional value of 40 degrees to 130 degrees. Results regarding general performance characteristics, specific air consumption and volumetric efficiencies, charge-air utilization, and effect of increased valve overlap on cylinder temperatures are provided.

Note presenting a wind-tunnel investigation to determine the low-speed stability and control characteristics of a complete model equipped with a vee tail. Tail dihedral angles of 35, 47, and 55 degrees were tested and the results were compared with results of tests of a conventional-tail arrangement used with the same wing-fuselage combination. The 47 degree vee tail was found to be the best-performing when lateral and longitudinal stability were concerned, and it contributed 40 percent more stability and 90 percent more dihedral effect than the conventional tail.

Report presenting an equation for calculating the heat flow required from the surface of an internally heated windshield in order to prevent ice accretions during flight in specified icing conditions. Results regarding the internally heated windshield characteristics, external discharge windshields, and prediction of heating requirements for both types of windshields are provided.

From Summary: "These properties compare favorably with those of the strongest similar alloys previously investigated. However, compared with a 60Cr-25Fe-15Mo alloy, the three cobalt-chronium-nickel cast alloys are inferior. A correlation of NACA and OSRD (Project NRC-8) data is presented, showing the variation of rupture strengths with temperature in the range of 1350^o to 2000^o for alloys."