"Airfoils with their trailing edge cut away are often found on aircraft, as the fins on the hulls of flying boats and the central section of the wings for affording better visibility. It was therefore of some interest to discover the effect of such cutaways on the lift and drag and on the position of the center of pressure. For this purpose, systematic experiments were performed on two different airfoils, a symmetrical airfoil and an airfoil of medium thickness, with successive shortenings of their chords" (p. 1).

The stability analysis of an airplane while rolling is much more simplified to the extent that it can be obtained for numerical data which can be put to practical use in the design of landing gear dimensions. Every landing gear type attains to a critical ground friction coefficient that decides the beginning of instability, i.e., nosing over. This study has, in addition, a certain interest for the use of wheel brakes.

This article deals principally with Professor Bairstow's experiments on autorotation, in which the wing is free to rotate about an axis in its plane of symmetry, which axis is parallel with the direction of the wind.

The present report deals with six-component measurements in the small tunnel of the DVL on a model of the BFW-M 27b(sub 1), which were made to determine the effect of rolling and yawing on the air forces and moments. The wind was given a spiral motion by means of a rotating screen, the model being suspended in the conventional manner. The lack of accuracy in the measurement of the rolling-yawing moments was very noticeable.

The equations of the individual processes of self nucleation are utilized through an electrical analogy to obtain the nucleation frequency. This process is shown to be shorter and less subject to error than that of previous investigators since the appearance of indeterminant integration constants is completely avoided. With the nucleation frequencies of crystals and spheres the Ostwald law of stages is reviewed and modified.

The propeller cannot be considered alone, but the mutual interference between propeller and airplane must be considered. These difficulties are so great when the joint action of propeller and airplane is considered, that the aerodynamic laboratory at Gottingen originally abandoned the idea of applying the efficiency conception of the test results. These difficulties and the methods by which they are overcome are outlined in this report.

"The optimum circulation distribution and hence the maximum theoretical thrust obtainable for contra-vanes fitted behind propellers is markedly dependent on the number of guide vanes. The outer portion of the vanes, even if projecting considerably beyond the edge of the propeller slipstream, still contribute appreciably to this theoretical gain of thrust. But, owing to the always existing friction of the vanes, the limit of the optimum vane length lies at relatively small diameters" (p. 1).

The accuracy of the instruments used for flight test measurements has been inadequate so a new series of tests were commissioned with the development of an accurate elevator setting recorder.

"When flying in a turn or pulling out of a dive, the airscrew exerts a gyroscopic moment on the aircraft, In the case of airscrews with three or more blades, arranged symmetrically, the value of the gyroscopic moment is J(sub x) omega(sub x) omega(sub y), where J(sub x) denotes the axial moment of inertia about the axis of rotation of the airscrew, omega(sub x) the angular upeed of the airscrew about its axis, and omega (sub Y) the rotary speed of the whole aircraft about an axis parallel to the plane of the airscrew (e.g., when pulling up, the transverse axis of the aircraft). The gyroscopic moment then tends to rotate the aircraft about an axis perpendicular to those of the two angular speeds and, in the came of airscrews with three or more blades, is constant during a revolution of the airscrew" (p. 1).

"A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and notch effects" (p. 1).

"The present report deals with the problems involved in the greater utilization and development of aircraft engine materials, and specifically; piston materials, cylinder heads, exhaust valves, and exhaust gas turbine blading. The blades of the exhaust gas turbine are likely to be the highest stressed components of modern power plants from a thermal-mechanical and chemical standpoint, even though the requirements on exhaust valves of engines with gasoline injection are in general no less stringent. For the fire plate in Diesel engines the specifications for mechanical strength and design are not so stringent, and the question of heat resistance, which under these circumstances is easier obtainable, predominates" (p. 1).

"Charts are presented for checking the stability of plane systems of rods, the use of the charts being illustrated by examples. It is also indicated how best to combine the individual members to form stable structures" (p. 1).

The problem of shimmy of a castering wheel, such as the nose wheel of a tricycle gear airplane, is treated analytically. The flexibility of the tire is considered to be the primary cause of shimmy. The rather simple theory developed agrees rather well with previous experimental results. The author suggests that shimmy may be eliminated through a suitable choice of landing gear dimensions in lieu of a damper.

"It would appear that welds in some stainless steels, heat-treated in some practicable way, will probably be found to have all the resistance to corrosion that is required for aircraft. Certainly these structures are not subjected to the severe conditions that are found in chemical plants. This article should be considered as an outline of what can be done, not necessarily as instructions, which will enable anyone to obtain satisfactory results in commercial work" (p. 1).

The building and flying of a glider is possible for anyone who can use a few basic tools. This report presents some plans and techniques for building your own glider.

A design for a wind vane is presented and various applications are discussed. The equations that can be used to calculate effects on the aircraft using the vane and control assistance that can be provided using the wind vane are provided.

Report presenting an exploration of the concept that the ratio between the volume and the surface area also exerts an influence on other secondary characteristics of airships.

The analytical results of Part I are also applied to sound dispersion by friction and heat conduction, An irreversible change of momentum, energy, and type of particle corresponding to friction, heat conduction, and diffusion effects can appear both in the direction of the sound field and traverse to it. Longitudinal damping, the coupling of longitudinal damping and that due to chemical and physical changes, and coupling of diffusion and compositional changes are treated for a plane sound wave of infinite extent.

Memorandum presenting a treatment of the problem of the differential isentropic changes of state in dissociating gases.

Experiments on the effect of atmosphere and of sea water on the building materials employed by us have been carried on for years in the North Sea with the aid of the Hamburg Naval Observatory. Parallel experiments are being made at the Pisa Naval Observatory in the Mediterranean Sea. Metal sheets, sections, assemblies and experimental floats are being exposed to the action of the elements. Different construction techniques are discussed and a variety of specific airplanes are presented which incorporate some of the new thinking.

"A number of semiempirical approximate methods exist for determining the characteristics of the turbulent boundary layer on a curvilinear surface. At present, among these methods, the one proposed by L. G. Loitsianskii is given frequent practical application. This method is sufficiently effective and permits, in the case of wing profiles with technically smooth surfaces, calculating the basic characteristics of the boundary layer and the values of the overall drag with an accuracy which suffices for practical purposes" (p. 1).

The volatile fuel of the high-speed internal combustion engine has, in the past, consisted almost exclusively of the lighter distillates from crude petroleum. Alternative and supplementary fuels are discussed such as: tetraline, dekalin, alcohol, cyclo-hexenes.

"The monocoque form of airplane construction has introduced a number of new problems to the stress calculator and the designer. The problems for the stress calculator fall into two groups: the determination of the stress condition (shell statics) and the determination of the failing strength (shell strength). The present report summarizes the most important theoretical and experimental results on this subject" (p. 1).

Any one endeavoring to solve the problem of soaring flight is confronted not only by structural difficulties, but also by the often far more difficult aerodynamic problem of flight properties and efficiency, which can only be determined by experimenting with the finished glider. The report primarily considers open-air experiments with glider models and some specific elements of gliders that have been studied using these experiments.