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.

"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).

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.

The present report contains the results of a few experiments on three airfoils to which the rear portions, having chords respectively 1/4, 1/3, and 2/5 of the total chords, are hinged so as to form ailerons, especial attention being given to the shape of the slot between the aileron and the main portion of the aileron.

Different methods for increasing the efficiency of diesel engines are presented and some new designs are given.

I am now proposing a method for the preliminary approximate calculation of the thrust distribution and efficiency of air propellers under any operating conditions. Our task becomes the following, namely, to determine the speed relations and the forces developed on a section with a given direction and velocity of the air current, a problem which can be solved with the aid of the momentum theory.

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.

This report presents methods to reduce the incidence of aviation accidents. Some of the methods discussed include enlistment and training of aviators, improvement of controls and control surfaces, and upgrading of power plants.

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.

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

"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).

Different applications of the slotted-wing principle are discussed as well as the advantages of using them. Slotted-wings are provided as a promising solution to the problem of needing to increase flight speed for aircraft while also decreasing landing speed.

The endeavor to draw a strict line between gliders and soarers as been recently abandoned and the following classification adopted: 1) gliders controlled by shifting the weight of the body; 2) gliders controlled by rudders; 3) gliders controlled by wings. The different classes are discussed as well as materials and parts used in construction.

Memorandum presenting a review of some of the German gliders produced from 1920-1923. The designs, flight characteristics, and descriptions of successful flights are provided.

The structural details such as wings, fuselage, landing gear, and steering organs of German gliders are detailed in this report.

Different engines are tested to determine their efficiencies in burning fuel. Fuel injection and ignition chamber engines are also discussed.

"Further progress toward the satisfactory solution of the difficult problem of the distribution and atomization of the injected fuel was made by extensive experimentation with various fuel valves, nozzles, and atomizing devices. Valuable information was also obtained through numerous experimental researches on the combustion of oils and the manner of introducing the combustion air into the cylinder, as well as on the physical processes of atomization, the determination of the size of drops, etc. These researches led to the conclusion that it is possible, even without producing great turbulence in the combustion chamber and at moderate pump pressure, if the degree of atomization and the penetrative power of the fuel jet are adapted to the shape of the combustion chamber and to the dimensions of the cylinder" (p. 1).

Ignition-chamber engines and their fuel injection systems are investigated. Specific details are provided for fuel-injection nozzles and fuel pumps are provided.

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.

Report investigating some characteristics of aircraft stall, including the following: Is the danger of stalling necessarily inherent in the airplane in its present form and structure, or can it be diminished or eliminated by suitable means? Do we possess such means or devices and how must they operate?

"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 calculations in this paper afford an approximate solution of the static stability. A derivation of the formulas for moment coefficient of a wing, moment coefficient of elevator, and the total moment of the combined wing and elevator and the moment coefficient with reference to the center of gravity are provided.

Different types of coatings to protect duralumin from corrosion are discussed. Plating, etching, brushing, coloring, painting and varnishing are all investigated.