"In undertaking to analyze the functioning conditions of a reduction gear on an aviation engine, we will consider an ordinary twelve-cylinder V-engine. The reduction gear employed consists either of a pair of spur gears, one of which is integral with the engine shaft and the other with the propeller shaft, or of a planetary system of gears" (p. 1).

Report presenting an investigation of the phenomenon of knocking in gasoline engines and some of the problems that it may cause. It is of the greatest importance, not only for automobile engines, but also for every other kind of internal combustion engine, since it limits the degree of compression and the thermal efficiency and its investigation indicates ways for saving fuel.

Now that the two-stroke-cycle engine has begun to make its appearance in automobiles, it is important to know what services we have a right to expect of it in aeronautics, what conditions must be met by engines of this type for use on airplanes and what has been accomplished.

This report describes the layout of the laboratory along with the motor and balance for the wind tunnel.

"We propose to show how to calculate the cooling capacity of all radiators through which the air flows in separate streamlets, whether enclosed in actual tubes or not and whatever cross-sectional shape the tubes may have. The first part will give the fundamental principles for calculating velocity of air in the tubes and the heat exchange by radiation, conduction and convection, and show, by examples, the agreement of the calculation with experiments. In the second part, the effect of the dimensions and conditions of operation on the heat exchange will be systematically investigated" (p. 1).

The use of duralumin by French airplane designers is presented, the results they have obtained, and their hopes for the future.

This report examines the cause and effect of the energy conversion in airless-injection engines. In order to obtain a criterion for the chosen working method, it takes into consideration the time relations between the individual processes. Observations of the engine alone do not suffice to obtain the necessary basis for a critical analysis of the processes.

Experimental data, such as the results of tank tests of models, render it possible to predict, at least in principle, as to how a hull or float of a given shape will comport itself. We will see further along, however, how uncertain these methods are and how they leave room for empiricism, which will reign for a long time yet in seaplane research bureaus.

The test equipment for studying the vaporization of heavy and medium oils is described as well as some of the experimental properties explored such as vaporization speed and diffusion coefficient. The experimental arrangement is also discussed.

The D.H. 66, constructed at Stag Lane Works of the De Haviland Aircraft Company built for Imperial Airways, Ltd. The fuselage has an all steel construction while the wings are made with box spars of wood and spruce ribs. It has a biplane tail and encloses the stabilizer trimming gear in a casing which serves to streamline the rear portion of the fuselage, but which is not part of the main structure. It weighs 9060 lbs. empty and 2500 lbs. after fueling with a total loaded weight of 14,700 lbs.

Report issued by the Bureau of Mines over studies conducted on red iron-ore mining near Birmingham, Alabama. Results of the studies are presented and discussed, as are mining methods. This report includes tables, illustrations, and photographs.

Report issued by the Bureau of Mines over investigations conducted on lignite. Preparation methods and uses of lignite are discussed. This report includes tables, maps, illustrations, and photographs.

Report issued by the Bureau of Mines over investigations conducted on lignite. Preparation methods and uses of lignite are discussed. This report includes tables, maps, illustrations, and photographs.

Report issued by the Bureau of Mines over the design of safe electrical accessories for use in mining equipment. Different types of electrical accessories are presented and discussed. This report includes illustrations.

The Avro Avian, designed by Mr. Chadwick of A.V. Roe & Co., Ltd. has a very low structural weight (estimated at 750 lbs. empty) but with sufficient structural integrity to be eligible of an "Aerobatics" certificate from the British Air Ministry. It can be configured as a monoplane, or a biplane with seaplane floats. It is designed for economical production.

Circular presenting a description of the Farman Jabiru F 3X, which was designed to satisfy the requirements of the aerial-navigation companies. Details regarding the power, wing, fuselage, landing gear, construction, engines, fuel tanks, characteristics, performance, drawings, and photographs are provided.

The Albatros was a two engine commercial biplane carrying 2 pilots, eight passengers, and 160 KG of baggage. The framework is metal, the wings having plywood and fabric over the steel tubing. The L 73 was the first 2 engine biplane to be made in Germany.

Circular presenting a description of the Arado Ar. S.I., which is a wireless biplane that is both physically attractive and highly performing. A description of the components, controls, construction, characteristics, flying qualities, drawings, and photographs are provided.

"This research on steel diaphragms was undertaken at the Langley Memorial Aeronautical Laboratory, as a part of a general investigation on fuel injection engines for aircraft. The work determined the load-deflection, load- deformation and hysteresis characteristics for single diaphragms having thicknesses from 0.00s inch to 0.012 inch, and for similar diaphragms tested in multiple having total thicknesses from 0.012 inch to 0.180 inch. The elastic limit loads and deflections, and rupture points of single diaphragms were also determined. Some work was done on diaphragms having central orifices in order to determine the effect of orifice diameter upon the load deflection characteristics" (p. 1).

"This report is the first of a series of four on propeller design and contains a description of the blade elements or modified Drzewiecke theory as used in the Bureau of Aeronautics, U.S. Navy Department. Blade interference corrections are used which were taken from R.& M. NO. 639 of the British Advisory Committee for Aeronautics. The airfoil characteristics used were obtained from tests of model propellers, not from tests of model wings" (p. 1).

This report is the second of a series of four on propeller design, and describes the method used to extend the data obtained from tests on a family of thirteen model propellers to include all propellers of the same form likely to be met in practice. This necessitates the development of a method of propeller analysis which when used to calculate the powers and efficiencies gives results which check the tests throughout their range.

"This report, the third of a series of four, describes a simple system for designing propellers of a standard form. In this report, the system is based on tests of a family of model propellers of standard Navy form, the data from which have been extended by means of calculations to cover the complete range likely to be found in practice. However, it can be worked out for any family having propellers of one general form" (p. 1).

"The object of this report, the last of a series of four on propeller design, is to describe a simple method for determining whether the strength of a propeller of a standard form is sufficient for safe operation. An approximate method of stress analysis is also given" (p. 1).

"The employment of steam power plants in aircraft has been frequently proposed. Arguments pro and con have appeared in many journals. It is the purpose of this paper to make a brief analysis of the proposal from the broad general viewpoint of aircraft power plants. Any such analysis may be general or detailed" (p. 1).