Investigations were made to develop a simplified method for designing exhaust-pipe shrouds to provide desired or maximum cooling of exhaust installations. Analysis of heat exchange and pressure drop of an adequate exhaust-pipe shroud system requires equations for predicting design temperatures and pressure drop on cooling air side of system. Present experiments derive such equations for usual straight annular exhaust-pipe shroud systems for both parallel flow and counter flow. Equations and methods presented are believed to be applicable under certain conditions to the design of shrouds for tail pipes of jet engines.

Note presenting a verification of previously derived equations for calculating the rate of heat transfer from airfoils in icing conditions, which have come about as a result of an investigation of the meteorological conditions conducive to the formation of ice on aircraft and a study of the process of airfoil thermal ice prevention. The results indicated that knowledge of these components has increased to a point where the design of heated wings on a fundamental, wet-air basis can now be undertaken with reasonable certainty.

From Summary: "Results of local-instability tests of H-, Z-, and C-section plate assemblies of four extruded aluminum alloys and two magnesium alloys, obtained in an extensive investigation to determine plate compressive strengths of aircraft structural materials, are summarized. On the basis of the general relationships found between the plate compressive strengths and the compressive stress-strain curves, methods applicable to flat plates and based upon the use of the compressive stress-strain curve are suggested for determining the critical compressive stress and the average stress at maximum load."

Report presenting a series of tests made with a CFR engine to determine the effect of inlet-valve capacity, inlet and exhaust pressure, and valve timing on the volumetric efficiency at various speeds. Three combinations of inlet and exhaust pressures and seven valve-timing arrangements were used.

Report presenting additional work in an investigation to determine the effects of preheating and postheating on the quality and strength of spot welds in aluminum alloys. The results showed that in alternating-current spot welding of aluminum alloys, the weld time is very important with regard to the quality of welds produced.

Note presenting a determination of the compressive buckling stress of outstanding flanges reinforced by bulbs using the torsion-bending theory for flanges with 54 shapes and a range of lengths. The results were analyzed to determine the shape of flange that gave the greatest support to the structure to which it was attached.

An introduction to the problem of determining the fundamental limitations on the performance possibilities of rocket-powered aircraft is presented. Previous material on the subject is reviewed and given in condensed form along with supplementary analyses. Some of the problems discussed are: 1) limiting velocity of a rocket projectile; 2) limiting velocity of a rocket jet; 3) jet efficiency; 4) nozzle characteristics; 5) maximum attainable altitudes; 6) ranges. Formulas are presented relating the performance of a rocket-powered aircraft to basic weight and nozzle dimensional parameters. The use of these formulas is illustrated by their application to the special case of a nonlifting rocket projectile.

Note presenting an investigation to determine the interference effects of three fuselages on the readings of a pitot-static tube extending various distances forward from the noses of the fuselages. The fuselages investigated were bodies of revolution with maximum diameters equal to 12 percent of the fuselage length and with circular-nose, elliptical-nose, and pointed-nose shapes. Results regarding interference at zero angle of attack, effect of free-stream impact pressure, and effect of tube diameter are provided.

Report presenting a method for determining the temperature and flow of heated gas necessary for ice prevention of hollow propeller blades in flight and icing conditions. A variety of conditions are taken into consideration and suggested simplifications and short methods are provided in order to not overcomplicate the design modifications.

Report presenting a detailed method for determining the temperature and flow of heated gas necessary for ice prevention of hollow propeller blades in flight and icing conditions. Expressions for the total external and internal heat transfer are combined to determine the surface temperatures of each segment.

Paper presenting a compilation of formulas, tables, and curves that have been found to be useful in the analysis of supersonic wind-tunnel data.

From Summary: "The Weissinger method for determining additional span loading has been used to find the lift-curve slope, spanwise center of pressure, aerodynamic center location, and span loading coefficients of untwisted and uncambered wings having a wide range of plan forms characterized by various combinations of sweep, aspect ratio, and taper ratio. The results are presented as variations of the aerodynamic characteristics with sweep angle for various values of aspect ratio and taper ratio. Methods are also included for determining induced drag and the approximate effects of compressibility."

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."

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.

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 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.

"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).

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 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.

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.

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.

"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).

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.