Experiments were made on the resistance of four airplane wheels of different sizes and coverings and two Lamblin radiators. The results show the important influence of the wheel coverings. The closing of a shutter, which was fitted to one of the radiators, considerably lessened the resistance.

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.

With an unsymmetrical wing and a rotating Magnus cylinder, the lift is produced by the superposition of parallel and circulatory flows. An explanation of the circulatory flow is furnished by the boundary-layer theory of Prandtl and the consequent vortex formation. According to this explanation, it must evidently be possible to increase the circulation either by increasing the size of the stronger (lower) vortex or by decreasing the size of the weaker (upper) vortex.

The main objective of these experiments was to determine how the air forces on the whole empennage are affected by varying the size of the elevator without changing the size of the whole empennage. The secondary objective was to determine how the magnitude of the air forces acting on the elevator (or the elevator moments) are affected by varying the angle of attack of the whole empennage, or of the elevator alone.

The following discussion is at first restricted to the light-oil engines now in use. We shall consider how far it is possible to reduce fire hazards by changes in the design of the engines and carburetors and in the arrangement of the fuel pipes.

This report describes experiences with a rotating cylinder to explore the effects of motion and flow upon human sensory organs. One observation was that the variation of the resultant line of gravity (from gravity and centrifugal force) was not felt so strongly as might be expected. The impressions produced by the physical effects on the members of the body, especially the ones caused by the deflecting force (Coriolis force), are exactly what the laws of physics would lead us to expect, although somewhat surprising when observed in one's own body.

Report presenting an examination of flexible piping and some of the difficulties involved in creating satisfactory flexible pipe. The joint used to assist in the flexibility of the pipe is illustrated and described.

The author discusses the safety record of airships in light of the accidents with the Roma and the ZR2.

A series of equations relating to airplanes are given and examples listed. Some of the equations listed include: the speed, altitude and carrying capacity of various airplanes; weight of an airplane; weight of various parts of an airplane; the polars of the wings; speeds of airplanes; radius of action.

Theories of ground effect and interference are explored as well as experimental methods to record the phenomenon. The consequences of the phenomenon on the airplane at take-off and landing are discussed.

"Following a qualitative discussion of the complicated process involved in a short-period, longitudinal force applied to an originally not quite straight bar, the actual process is substituted by an idealized process for the purpose of analytical treatment. The simplifications are: the assumption of an infinitely high rate of propagation of the elastic longitudinal waves in the bar, limitation to slender bars, disregard of material damping and of rotatory inertia, the assumption of consistently small elastic deformations, the assumption of cross-sectional dimensions constant along the bar axis, the assumption of a shock-load constant in time, and the assumption of eccentricities on one plane" (p. 1).

The present report gives the results of tests which were made for the purpose of solving the problem of whether diagrams obtained from pressure tests could be conclusive for the determination of the safe impact coefficients. It is first established that the rubber rings adhere firmly to the compression surfaces during deformation. Suggestions are thus obtained for a constructive simplification of the rubber rings. The hysteresis phenomenon is ascribed to external and internal friction forces. A device for falling tests is then described with which the process of shock absorption with rubber rings was tested.

Wind-tunnel tests are described, in which the angle of attack of a wing model was suddenly increased (producing the effect of a vertical gust) and the resulting forces were measured. It was found that the maximum lift coefficient increases in proportion to the rate of increase in the angle of attack. This fact is important for the determination of the gust stresses of airplanes with low wing loading. The results of the calculation of the corrective factor are given for a high-performance glider and a light sport plane of conventional type.

This report presents various methods for increasing the power of engines such as supercharging and turbocharging.

From Summary: "The application of the well-known basic principle of mechanics, the principle of Jourdain, to problems of the theory of the boundary layer leads to an equation from which the equations of Von Karman, Leibenson, and Golubev are derived as special cases. The given equation may be employed in other integral methods. The present paper deals with the method of the variation of the thickness of the boundary layer. A number of new approximate formulas valuable in aerodynamic calculations for the friction distribution are derived from this procedure. The method has been applied only to laminar boundary layers, but it seems probable that it may be generalized to include turbulent layers as well."

"In a previous paper, results are presented of accurate investigations of the processes of titanium carbonization and the succeeding titanium carbide decarbonization as related to the phenomenon of the graphitization of soot by heating at a constant temperature in atmospheres of pure hydrogen and carbon monoxide. These tests showed that the processes of titanium carbonization-decarbonization in an atmosphere of pure gases without nitrogen proceed in the same direction as the analogous processes under the conditions of the production furnace. In this case, however, the presence of admixtures of nitrogen changes the quantitative results of the decarbonization process" (p. 1).

"The investigation of the flow in a centrifugal pump indicated that the flow patterns in frictional fluid are fundamentally different from those in frictionless fluid. In particular, the dead air space adhering to the section side undoubtedly causes a reduction of the theoretically possible delivery head. The velocity distribution over a parallel circle is also subjected to a noticeable change as a result of the incomplete filling of the passages" (p. 1).

Memorandum presenting an investigation to determine the variations in the velocity of the air when it was obliged to flow about a wing profile. Special interest was paid to the determination of velocity as compared with that of the undisturbed flow and of the velocity drop in successive planes perpendicular to the flow direction at increasing distances from the wing profile.

This paper is a presentation of the experiments and equipment used in investigations at the Guidonia wind tunnel. The equipment consisted of: a number of subsonic and supersonic cones, an aerodynamic balance, and optical instruments operating on the Schlieren and interferometer principle.

"At the request of the Junkers Aircraft and Engine Construction Company, Engine Division, Dessau Main Plant, an investigation was made using the interferometer method on the two turbine-blade profiles submitted. The interferometer method enables making visible the differences in density and consequently the boundary layers that develop when a flow is directed on the profile. Recognition of the points on the profile at which separation of flow occurs is thus possible" (p. 1).

Unfortunately the problem of laying out an air route has been approached by all who give it consideration as one of the hardest tasks in the world. Whereas, as a matter of fact, a very serviceable air route can be laid out with an absolute minimum of ground work.

This report presents some studies of maritime aviation which cover the following principal points: employment of landplanes on maritime aerial warfare; their adaption to peculiar requirements of the Navy; and the establishment of a method of aerial pursuit and bombardment, likewise adapted to military aviation over land.

"The Institut Scientifique Experimental des Transports at Moscow established toward the end of 1925 had since its inception included in its program the study of the mechanism of plastic deformation and the problems associated with it with reference to the materials of the means of transport. Before the program thus determined upon could be carried out, it was necessary to adopt a method of research, or, more exactly, a system of such methods. Because of the modest equipment of the laboratory of the recently established institute, the choice of any particular method was determined not only by the advantages it offered but also by the resources available. As a result of a series of studies and investigations, a method was determined upon which in this paper will be denoted as the micromechanical method" (p. 1).

"The mechanical and electrical construction of a new experimental instrument for fatigue testing riveted and welded joints is described. This experimental device has the advantage of being able to stress, even with comparatively low magnetic exciter force, structural components in alternate bending by resonance vibrations up to incipient fatigue failure (p .1)".