Memorandum presenting a description of a competition to produce an airplane suitable for school work. The characteristics evaluated included the speed range, take off, landing, reliability, and high and low speed are provided. A variety of monoplanes and biplanes were entered and a description of each and their blueprints are provided.

In studying the application of his system of varying the camber of airfoil sections, Mr. Lachassagne has just obtained a series of airfoil sections whose polar envelope presents truly remarkable aerodynamic properties.

The first part of this report shows the differences between commercial and war airships and then goes on to show how some of the problems were solved. Their thorough investigations of these problems finally enabled the Schutte-Lanz Company to construct bulkhead diagrams for determining the buoyancy of airships, by means of which the size of each cell was established. These diagrams were derived from bulkhead diagrams employed in ship designing and are used in a similar manner.

The author describes experiments in designing nonrigid airships. A nonrigid airship of 32,000 cubic meters, the PL 27 withstood all stresses with 20 kg/m(exp 2) hull pressure during its life of two years. The moment of resistance is known, as also the stresses in the envelope for the given hull pressure. The mean internal pressure necessary to give the airship the requisite rigidity and to prevent buckling was also investigated.

"The Commissariat of Aviation deems it expedient to issue a few rules of a general character which should be followed by constructors in designing aircraft, into the manufacture of which metal enters to a considerable extent. The materials covered include: aluminum, duralumin, soft steel, high-resistance steel, in sheets, tubing, and shaped elements" (p. 1).

The problems as to how an airship can best be stabilized and steered and to what stresses it is subjected in the air, are so important as to determine in large measure the future development of airships much more than formerly when velocities of 30-35 meters (98-115 feet) per second were not known and the effects of the air flow were not so great.

The purpose of this paper is to summarize the present status of the problem of mooring airships. Mooring with one, two and even three cables are all discussed.

A historical sketch of duralumin is presented, especially in regards to its manufacture by various countries. The properties of duralumin are discussed and strength characteristics listed. Increasing the hardness of duralumin by tempering is discussed as well as the uses of the metal.

This report recounts some of the successful experiments conducted in England and Germany on slotted wings and ailerons. Wind tunnel test results are given and examples of aircraft constructed with these new wing components are described.

The laboratory instruments, which we often constructed with makeshift means, gave encouraging results and showed that they could satisfactorily meet the required conditions. By limiting ourselves to the employment of hot wires of 0.05 mm (0.002 in.) diameter, we obtained instruments which faithfully followed all the wind fluctuations of over 0.1 second and even much more rapid variations without any very great error.

The present article is a brief report on the development and testing of the Messerschmidt glider that set a duration record of 21 minutes. Its most conspicuous characteristic was the placing of the steering gear entirely inside the fuselage and wings.

"The question of behavior of a streamlined body with round or square cross-sections is of importance in determining the shape to give an airplane fuselage. It is our task here to show how the lift and drag are affected, with the object placed obliquely to the air stream" (p. 1).

"The crisis which troubles the world market for liquid fuel in general and for carburants in particular is doubtless one of the most serious ever experienced by modern industry. It is a national crisis of economic and political independence for countries like Italy and France. The solutions suggested for meeting the lack of liquid fuel may be summed up under two general headings: the economical use of the petroleum now available; creation of petroleum substitutes from natural sources within the country" (p. 1).

"The air is known to be charged with electricity (chiefly positive) with reference to the earth, so that its potential increases with the altitude and the difference in potential between two points in the same vertical line, divided by the distance between them, gives a value called the "potential gradient," which may vary greatly with the altitude, the nature of the ground and the atmospheric conditions" (p. 1).

The improvement of airplanes and increased safety of air traffic can be sought in various ways. In the experiments described below, the aim was to find some simple and inexpensive method of modifying present-day airplanes, so as to improve and simplify the process of landing.

"In opposition to the advantage of larger dimensions, there is one disadvantage, namely, the weight of the structure increases more rapidly than the buoyancy. It is not possible, however, to determine a general law. In order to formulate one having the merit of simplicity, we will divide the structure into two parts: one subject to tensile and compressive stresses, varying directly as the ascensional or lifting forces; the other subject to varying stresses of the surface areas" (p. 1).

This report describes the apparatus used to take air-flow photographs. The photographs show chiefly the spiral course of the lines of flow near the tip of the wing. They constitute therefore a visual presentation of the phenomena covered by airfoil theory.

"The purpose of this memorandum is to present in a concise form a description, with drawings, of the most practical light airplanes participating in the meet at Lympne, England, in October, 1923. Features, which are particularly suitable for this type of aircraft, are described and a special reference is made to achievements which indicate progress and possibilities both from a commercial and a military point of view" (p. 1).

This report provides a description of the wind tunnel housing and motors at the Belgian Service Technique de L'Aeronautique.

Report presenting some tests to determine the influence on initiating combustion in a one-cylinder compression ignition engine of inlet air temperature and jacket water temperature. The results show that the engine is very sensitive to changes in final compression pressure, induced by a change in the initial compression pressure, and that some way of providing compensating means for conditions that tend to lower section pressure is necessary.

From Introduction: "Coal dust as an agent of widespread explosions had been under suspicion, and watering to allay the dust was recommended by some mining engineers but the watering of coal-mine dust was adopted in comparatively few mines of the United States and Great Britain, and had not been introduced widely in any country except Germany. Rock dusting, another method of preventing explosions of coal dust, was early tested with success by the Bureau of Mines in its first gallery at Pittsburgh and, beginning in 1911, at the experimental mine, Bruceton, Pa."

From Scope of Bulletin: "The material presented is divided into two main parts. Part I describes the evaporative tests of the marine water-tube boilers, and Part II describes the evaporative tests of the Scotch marine boiler."

From Introduction: "However, before the flame lamp becomes obsolete, it is fitting that the Bureau of Mines compile a permanent record of a device which has served the mining industry for more than three generations, and not only made possible the development of entire districts that otherwise could have not been worked but undoubtedly saved the lives of thousands of underground workers."

From Scope of Bulletin: "This bulletin reviews, in the light of the recent experience, the use of production-decline curves in estimating the future production of oil from wells. The bulletin does not deal with costs, oil prices, or the methods of evaluating oil properties."