Technical report with short reports from the (1) Physics Section I; (2) Physics Section II ; and (3) Physics Section III.

From Summary: "In order to provide a basis for judging the relative importance of wing failure by fatigue and by single intense gusts, an analysis of wing life for normal cruising flight was made based on data on the frequency of atmospheric gusts. The independent variables considered in the analysis included stress-concentration factor, stress-load relation, wing loading, design and cruising speeds, design gust velocity, and airplane size. Several methods for estimating fatigue life from gust frequencies are discussed."

Abstract: "An investigation of the mercury salvage program has resulted in the development of an improved high compacity type of distillation apparatus. The still, electrically heated and essentially automatic in its operation, will produce at a rate greater than 75 pounds per hour and develop a product 99.99% pure or better. This still will handle the lowest grade crude of amalgam that can pass through the feed lines and will continue to develop a pure prodcut for comparatively long periods of time. The clean-out operation is amazingly simple and convenient and may be done within one-half hour while the apparatus itself is still hot. Two models of this design are scheduled for installation in a mercury recovery room of the Alpha Analytical Department of Building No. 9207."

This report describes progress in testing the corrosion resistance of alloys of TCl₄. The steps and conditions of the testing procedures are given as well as conclusions and photos of TCl₄.

The results of an investigation of submerged-duct entrances are presented. It is shown that this type of entrance possesses the following characteristics: 1) very high-critical-compressibility speeds throughout the range of high-speed inlet velocity ratios; 2) very low pressure losses for the air entering the duct at all inlet-velocity ratios; and, 3) low external drag. These characteristics are obtained by the proper shaping of the contour of the upstream approach to the submerged inlets and by proper alignment of the duct lip. Design data are presented and the application of these data to a specific high-speed fighter-airplane design is discussed.

Report discussing an investigation to determine whether the crank angle for maximum rate of pressure rise can be used to indicate maximum-economy spark advance. Information about spark-advance tests at constant inlet-air pressure and fuel-air-ratio test results are provided.

"Tests were conducted to determine the effect of engine-operating variables and internal coolants on spark-advance requirements of a single cylinder from a 12-cylinder liquid-cooled engine for maximum take-off power and maximum cruise economy. The effects of fuel-air ratio, engine speed, air flow (charge density), mixture temperature, and internal coolants on peak-power (optimum) spark advance were investigated. In addition, tests were conducted to determine the effect of spark advance on the knock-limited engine performance at several mixture temperatures for conditions simulating take-off, high-power cruise, and low-power cruise" (p. 1).

Technical report with six sections describing the process: (1) The reaction of HN)3 with HSCN; (2) The distribution of nitric acid between hexone and water; (3) The distribution of HSCN between hexone and water; (4) The solubility of thorium sulfate in various extraction solutions; (5) The distribution of protoactinium and fission elements between hexone and aqueous thiocyanate solutions; and (6) Separation of uranium from thorium by extraction into hexone as UO2(SCH)a.

Technical report discussing that the deuterium concentration of heavy water can be determined by equilibrating the water with deuterium gas in the presence of a catalyst with subsequent analysis of the equilibrated gas on the mas spectrometer. The apparatus for equilibration analyses maybe be considered in three parts: 1) apparatus for introducing the ingredients into the reaction chambers; 2) the reaction chambers; 3) the mass spectrometer for analysis of the equilibrated gas. The isotopic composition of the deuterium gas to be used as the starting material is primarily governed by what gases are available. In general it is best to use gas within about one percent on either side of the final equilibrium composition. No reaction takes place between deuterium gas and water molecules in the absence of a catalyst. Platinum oxide is used as the catalyst.

From abstract: "A simple electronic circuit is described, the use of which greatly improves the temperature regulations obtainable with Beta equipment. The circuit utilizes the time derivative of the temperature to counteract oscillation and overshoot. No other changes are required in existing equipment for installation of the stabilizer."

Abstract. to estimate the oxygen picked up by thorium in casting a rapid method of running the acid insoluble content was developed. the quickest procedure consists of reacting with mixed acids, fuming with perchloric and filtration to separate the "free" thorium from the "combined". The precipitate is ignited and weighed as thorium dioxide.

Report discussing the results of testing on the suitability of six aromatic amines as fuel additives. Antiknock effectiveness, availability, physical properties, and chemical properties for knock tests were explored. The six aromatic amines were xylidines, cumidines, N-methylxylidines, N-methylcumidines, N-methylaniline, and N-methyltoluidine in 28-R aviation fuel.

"Low-aspect-ratio wings having pointed plan forms are treated on the assumption that the flow potentials in planes at right angles to the long axis of the airfoils are similar to the corresponding two-dimensional potentials. For the limiting case of small angles of attack and low aspect ratios the theory brings out the following significant properties: (1) The lift of a slender, pointed airfoil moving in the direction of its long axis depends on the increase in width of the sections in a downstream direction. Sections behind the section of maximum width develop no lift. (2) The spanwise loading of such an airfoil is independent of the plan form and approaches the distribution giving a minimum induced drag. (3) The lift distribution of a pointed airfoil travelling point-foremost is relatively unaffected by the compressibility of the air below or above the speed of sound. A best of a triangular airfoil at a Mach number of 1.75 verified the theoretical values of lift and center of pressure" (p. 1).

Low-aspect-ratio wings having pointed plan forms are treated on the assumption that the flow potentials in planes at right angles to the long axis of the airfoils are similar to the corresponding two-dimensional potentials.

Report discussing a study of automatic nonreturn air valves for use in an intermittent-jet engine. Four valve-spring materials, three valve-grill materials, and five types of valves were used. Valve A, which was made out of aluminum, was found to perform the best and last the longest.

As part of a general investigation of propellers at high forward speeds, tests of two-blade propellers having the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 blade designs were made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.70 to determine the effect of camber and compressibility on propeller characteristics. Results previously reported for similar tests of a two-blade propeller having the NACA 4-(3)(08)-03 blade design are included for comparison.

A general representation of fan and turbine arrangements on a single classification chart is presented that is made possible by a particular definition of the stage of an axial-flow fan or turbine. Several unconventional fan and turbine arrangements are indicated and the applications of these arrangements are discussed.

Report discussing the effects of Mach number on the aerodynamic characteristics of an Allison powered single-engine pursuit airplane. Information about the lift, drag, pitching-moment characteristics, stability, tail effectiveness, and elevator effectiveness with Mach number is provided.

Report issued by the U.S. Bureau of Mines discussing the iron-ore mining accident experience in the Lake Superior District. Frequency and severity rates of accidents between 1940 and 1943 are presented. This report includes tables.

The results of this analysis indicate that isothermal pressure losses can be predicted analytically in the type of ducting system which may be broken down into the elementary forms of elbows, diffusers, and straight ducts for which pressure-loss data are published.

"The knock-limited performance of blends containing General Motors triptane in S reference fuel and in an S plus M base fuel was determined in 17.6, F-3, F-4, and full-scale (single cylinder) engines. The results obtained are presented and are compared with published data from similar tests of 12 aromatics, 10 paraffins (including highly purified triptane), and 2 olefins. The comparison of fuels - which is based on a consideration of (a) antiknock blending sensitivity, (b) lead susceptibility, (c) temperature sensitivity, and (d) comparison of small-scale and full-scale engine data - is presented by means of bar graphs" (p. 1).

Report presenting a method of correlating the effects of compression ratio and inlet-air temperature on the knock limits of aviation fuels. Knock-limited performance tests of several fuels were run to check the method.

Report presenting an investigation to determine the effect of the amount of oil flow to the piston on the ring-sticking characteristics of a piston and ring assembly and on the engine oil consumption. Results regarding the blow-by, lubrication, oil consumption, and method of supplying oil are provided.

Report presenting a method for making lifting-surface calculations by means of magnetic measurements of an electromagnetic-analogy model. The method is based on the perfect analogy between the strength of the magnetic field around a conductor and the strength of the induced-velocity field around a vortex.