"This note describes tests of an adjustable blade metal model propeller, both in a free wind stream and in combination with a model fuselage, at four settings of the blades. The model propeller is designed for a uniform nominal pitch/diameter ratio of .7 and the blade settings used correspond to nominal pitch/diameter ratios of .5, .7, .9, and 1.1 at the .6 radius. The tests show that propellers of this type may be considerably changed in setting from the designed pitch angles and yet give excellent performance" (p. 1).

Discussed here are problems with the use of cowlings with radial air cooled engines. An XF7C-1 airplane, equipped with service cowling and with narrow ring, wide ring, and exhaust collector ring cowlings over the service cowling, was used. For these four cowling conditions, the rate of climb and high speed performance were determined, the cylinder conditions were measured, and pictures to show visibility were taken. The level flight performance obtained with an engine speed of 1900 r.p.m. for the service type, the narrow ring, the wide ring, and the exhaust collector ring was 144.4, 146.6, 152.8, and 155 mph, respectively.

Note presenting injection lags determined for a common-rail fuel injection system for a compression-ignition engine. The system consisted of a high-pressure reservoir, a timing valve, an injection valve tube, and an automatic injection valve. Results regarding the variable injection valve tube length, variable tube diameter, variable valve opening pressure, variable injection pressure, and variable initial pressure are provided.

Memorandum presenting an investigation concerning the limits of detonation in gaseous mixtures. In regards to the results, by progressive dilution of the explosive, the course of the chemical reaction becomes slower and slower until finally the transformation within the reaction zone becomes so slow that it is not there completed.

The purpose of this study was to investigate the strength of continuous beams after the elastic limit has been passed. As a result, a method of calculation, which is applicable to maximum load conditions, has been developed. The method is simpler than the methods now in use and it applies properly to conditions where the present methods fail to apply.

"The object of this investigation is to make available to the aircraft industry authoritative information on the strength, weight, and cost of a number of types of welded joints. This information will, also, assist the aeronautics branch in its work of licensing planes by providing data from which the strength of a given joint may be estimated. As very little material on the strength of aircraft welds has been published, it is believed that such tests made by a disinterested governmental laboratory should be of considerable value to the aircraft industry" (p. 323).

This report presents the comparative flight results of a roots supercharger and a turbocentrifugal supercharger. The tests were conducted using a modified DH-4M2 airplane. The rate of climb and the high speed in level flight of the airplane were obtained for each supercharger from sea level to the ceiling. The unsupercharged performance with each supercharger mounted in place was also determined. The results of these tests show that the ceiling and rate of climb obtained were nearly the same for each supercharger, but that the high speed obtained with the turbocentrifugal was better than that obtained with the roots. The high-speed performance at 21,000 feet was 122 and 142 miles per hour for the roots and turbocentrifugal, respectively.

This report presents the results of an investigation to determine (1) the magnitude and distribution of aerodynamic loads over the wings and tail surfaces of a pursuit-type airplane in the maneuvers likely to impose critical loads on the various subassemblies of the airplane structure, (2) To study the phenomenon of center of pressure movement and normal force coefficient variation in accelerated flight, and (3) to measure the normal accelerations at the center of gravity, wing-tip, and tail, in order to determine the nature of the inertia forces acting simultaneously with the critical aerodynamic loads. The results obtained throw light on a number of important questions involving structural design.

Report issued by the U.S. Bureau of Mines discussing the mining practices and expenses of the United Verde open-pit mine west of Jerome, Arizona. As stated in the introduction, "the purpose of this paper is to present the methods used in developing and operating the mine, and to discuss the problems encountered" (p. 1). This report includes tables, maps, and illustrations.

This survey is intended to give a general approximate idea of the stability and controllability of German airplanes. Both flight characteristics, including the behavior of the airplane under the action of deflected controls and external disturbances, and flight performance, which refers to climbing, speed, take-off, and landing qualities.

Memorandum presenting an investigation to determine quantitatively the limits of detonation in gaseous mixtures for the conditions imposed and for a number of given gaseous explosive mixtures.

This report presents methods determining the hardness and tensile strength of metals by showing the effect and dependence of the hardness numbers on the strain-hardening. Relations between the hardness numbers and the ordinary stress-strain diagrams and tensile strength are given. Procedures for finding the Brinell strength are also presented.

Circular presenting a description of the Le 0.240, which is a cantilever monoplane invented by the Lioré-Olivier Company. Information regarding the wings, profile, fuel tanks, construction, ailerons, hull, controls, and flight characteristics is provided.

Circular presenting a description of the Dornier Do.X flying boat. Details are provided regarding the structural details, flying qualities, and photographs.

Circular describing the Comper C(La)7 Swift airplane, which is a high-wing single-seat monoplane with performance equal to that of a modern two-seat light airplane. Details of the view, aerodynamic design, wing, landing gear, cockpit, fuel tanks, engine, characteristics, drawings, and photographs are provided.