Gas and electric welding of duralumin are discussed. Some of the elements that go into determining a successful weld and inspecting for faults are also described.

"At the suggestion of Professor Von Karman, I have made a few theoretical investigations of the mutual reaction of the wings and body of an airplane. There was assumed as the basis of my calculations, a strongly idealized body shape, namely, a cylinder extended to infinity at both ends and having its axis parallel to the direction of motion of the airplane. The results are to be regarded as rough approximations for a long airplane body and also for an airship with fins. In my calculations, I have considered only a monoplane in which the axis of the wing is rectilinear" (p. 1).

The object of this report was to indicate that we frequently only make use of 50 percent of the maximum brake horsepower of the engine in taking off the ground, that this loss is not inevitable, and that the effort to get engines of low weight per horsepower by boosting revolutions is of very little use to bombers and commercial airplanes.

It is stated that the index value 6000, as found in normal tests of wing sections with a 20 cm chord, falls in the same region where the transition of laminar to turbulent flow takes place on thin flat plates. It is to be expected that slightly cambered, thin wing sections will behave similarly. The following test of two such wing sections were made for the purpose of verifying this supposition.

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.

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.

We will here report on the effects of coarsely roughening not only the pressure side but also the suction or upper side of airfoils, as the first group of a larger series of experiments.

"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).

Experiments were carried out using a special engine with small glass windows and a stroboscope to record various aspects of engine performance. Valve position, supercharging, and torque recoil were all investigated with this experimental apparatus.

Report discussing before proceeding to discuss the preparation of dope solutions, it will be necessary to consider some of the essential properties which should be possessed of a dope film, deposited in and on the surface of an aero fabric. The first is that it should tighten the material and second it should withstand weathering.

Memorandum describing the flights of Charles Lindbergh and some of the calculations that go into the determination of the amount of fuel required, drag, and weight for his trip.

The results of the velocity measurements in the boundary layer described in NACA-TM 411 are here discussed in greater detail. The measurements made were of the velocity distribution in the vicinity of an airfoil model fitted with a rotary cylinder and were undertaken for the purpose of obtaining a closer insight into the phenomena observed in experimenting with this model.

This part of the report presents characteristics and graphic representations of water resistance. The laws of similarity are discussed as well as the theory of model tests. The test procedures and model tests of other countries are also discussed.

Different float designs are presented and the investigations are discussed.

A variable flap gear, which would function automatically and require no attention during flight appeared to be an attractive idea even in its early stages of development. The advantages of variable camber are described as well as the designs of these automatic flaps.

The types of corrosion and factors of corrosion of duralumin are investigated. Salt water is the most common of the corroding media with which designers have to contend in using duralumin in aircraft and ships.

"One of the most striking phenomena which accompany the flow of fluids such as air and water about bodies, is that of changes in character. This phenomena is still very little understood. We will first discuss the nature of these changes and then show that pure theory leads to a multiplicity of characters of flow, among which we will endeavor to indicate those bearing some analogy to experimental results" (p. 1).

In this report is described an experimental method which the writer has evolved for dealing with air-cooled engines, and some of the data obtained by its means. Methods of temperature measurement and cooling are provided.

Memorandum presenting a description of the Paris Aero Show and some of the aircraft that the author observed there. A specific description of some of the designs is provided, as well as some technical drawings of particular elements of these aircraft.

This report presents a description of the design of the Cuatro Vientes wind tunnel.

The Arado SC 1 is a staggered overhung biplane. It was build specifically as a training aircraft. A description of the aircraft design, the flight characteristics, and photos of the aircraft are provided.

Circular presenting a description of the Focke-Wulf F.19 Ente, which is a tail-first airplane that was the first to fly under proper control. Details regarding the design, construction, controls, power unit, flight characteristics, and photographs are provided.

The Stinson S M-1 seats 5 passengers and a pilot. It is equipped with a Wright Whirlwind Engine. A description of the fuselage, cabin, power plant, gasoline supply, controls, wings, landing gear, lift struts, tail group, characteristics, drawings, and photographs are provided.

The H.D. 40 has a compound structure in which metal has been used at stress points. It is powered by one BMW IV 460 H.P. engine.