This investigation attempts to surpass the boundaries of pure mathematical interest in that it possesses as an example, a flow investigation in a multiply-connected region. Then the results appear to be carried out by means of an appropriate conformal representation of the region around two chosen closed curves. Thus we have the basis of an exact plane theory of the biplane.

"On the assumption of infinitely small disturbances the author develops a generalized integral equation of airfoil theory which is applicable to any motion and compressible fluid. Successive specializations yield various simpler integral equations, such as Possio's, Birnbaum's, and Prandtl's integral equations, as well as new ones for the wing of infinite span with periodic downwash distribution and for the oscillating wing with high aspect ratio. Lastly, several solutions and methods for solving these integral equations are give" (p. 1).

The characteristics of the position and form of the transition surface through the critical velocity are computed for flow through flat and round nozzles from subsonic to supersonic velocity. Corresponding considerations were carried out for the flow about profiles in the vicinity of sonic velocity.

A method is described by means of which the laminar friction layer at a wall with arbitrary pressure distribution may be calculated from Prandtl's boundary-layer equations.

This report details the methods of construction employed by the Gloster Company in their fabrication of metal aircraft parts. Ribs, spars, wings, and metal treatments to prevent oxidation are all discussed.

The conclusion of a previous article by Pistolesi is that the increment of lift due to ground effect is largely attributable to the effect of induction of the free vortices, and is practically equivalent to a virtual increase in aspect ratio. The ground clearance was of the order of magnitude comparable to the wing chord. New reports by Le Seur and Datwyler treat the case of minimum distance from the ground and is confined to the plane problem only. The author briefly reviews these reports and also one by Timotika. References to all the reviewed reports are in the attached bibliography.

"The object of this article is to set forth the particular properties of swiftly-moving air, how these affect the installation of a wind tunnel, the experimental results already obtained, the possible applications of such a tunnel, and what can be easily accomplished at the present time" (p. 1).

"This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed" (p. 1).

This report analyzes the heating and vaporization process of fuel droplets in a compression-ignition engine on the basis of the theory of similitude - according to which, the period for heating and complete vaporization of the average size fuel drop is only a fraction of the actually observed ignition lag. The result is that ignition takes place in the fuel vapor air mixture rather than on the surface of the drop. The theoretical result is in accord with the experimental observations by Rothrock and Waldron. The combustion shock occurring at lower terminal compression temperature, especially in the combustion of coal-tar oil, is attributable to a simultaneous igniting of a larger fuel-vapor volume formed prior to ignition.

"Following the development of the well-known differential equations of the problem and their resolution for failure in tension, the bending (transverse) oscillations of an originally not quite straight bar hinged at both ends and subjected to a constant longitudinal force (shock load) are analyzed. To this end the course of the bar form is expanded in a sinusoidal series, after which the investigation is carried through separately for the fundamental oscillation and the (n-1)the higher oscillations. The analysis of the fundamental oscillation distinguishes three cases: shock load lower, equal to, or higher than the Eulerian load" (p. 1).

"The effect of application of power, so far not clarified, is investigated in the present report in order to give the pilot, in addition to the control measures, an expedient for spin recovery of multiengine airplanes. To this end, a series of spins was performed with an airplane of the Go 150 type. It was possible to set up a uniform rule regarding the effect of power, for right end left spins as well as for any combination of the direction of rotation of the propellers" (p. 1).

This report presents experiments in which two parts of the wing were arranged so as to form a biplane, which was subjected to normal three-component measurements, the two parts being placed in various relative positions with respect to the gap a and the stagger b.

Memorandum presenting an investigation conducted in the supersonic wind tunnel on a 16-inch ramjet that was equipped with an afterburner and used gaseous hydrogen for both the primary and afterburner fuels. The primary nozzle had a contraction ratio of 0.6 while the exit nozzle had a contraction ratio of 0.9. Data were obtained at a free-stream Mach number of 3.0 and zero angle of attack.

This report presents methods by which it is possible to determine, in a simple manner, both pressure atomization and carburetor atomization.

Memorandum presenting the mutual action of wing and fuselage, which greatly affects the construction of airplanes. A description of systematic wind-tunnel tests that were made to answer that question is provided. Other tests deal with the transition from fuselage to wing root, which, if inadequate on low-wing monoplanes, may become dangerous by causing the air flow to separate at the wing root.

This paper presents an account of Italian high-speed engine designs. The tests were performed on the Fiat AS6 engine, and all components of that engine are discussed from cylinders to superchargers as well as the test set-up. The results of the bench tests are given along with the performance of the engines in various races.

In part I of the paper the theory of flame propagation is developed along the lines followed by Frank-Kamenetsky and one of the writers. The development of chain processes in flames is considered. A basis is given for the application of the method of stationary concentrations to reactions in flames; reactions with branching chains are analyzed. The case of a diffusion coefficient different from the coefficient of temperature conductivity is considered.

The theory of landing impact is briefly stated and the applicability of a previously suggested formula is extended. Theoretical considerations regarding impact measurements on models and actual seaplanes are followed by a brief description of the instruments used in actual flight tests. The report contains a description of the strength conditions and deals exhaustively with force measurements on the float gear of an "HE 9a" with flat-bottom and with V-bottom floats. The experimental data are given and compared with the theoretical results.

This article presents a recounting of the Rhon soaring competition with emphasis on new designs, results, and prizes awarded. A round-robin discussion is also included at the end of the report.

"The NACA 23012-4 airfoil was investigated for the purpose of increasing lift by means of blowing out air from the wing, in conjunction with the effect of plain flap of variable contour and slotted flap of 25 percent chord length. The wing also was provided with a hinged nose, to be deflected at will. Air was blown out from the wing immediately in front of the flap; also at the opening between wing and hinged nose,tangentially to the surface of the wing" (p. 1).

"For an infinitely long plate strip of constant curvature there is set up the buckling condition for combined shear and axial stresses. Assumptions are made of the vanishing of the moments acting on the longitudinal edges and of the vanishing of the tangential displacements u and the transverse stresses sigma(sub y) (longitudinal stiffeners nonresistant to bending in the circumferential direction). The buckling condition is evaluated for the case of pure shear and an approximate formula is derived for the critical stresses for large curvatures" (p. 1).

Certain principles are common to all metal spars and the design of a particular metal spar is followed throughout the design process.

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.

In the first part of this paper we shall present the theoretical side of the problem of constructing curved model forms and the method of testing the model. In the second part we shall present a detailed account of the first experiments according to the given method, carried out with a curved model of the nonrigid airship V-2, and a comparison of the experimental results with some data of full-scale tests made with this airship in 1933.