This report presents a thermodynamic basis for rating heat engines. The production of work by a heat engine rests on the operation of supplying heat, under favorable conditions, to a working fluid and then taking it away.

The tests at the Gottingen laboratory included: friction tests on a surface treated with emaillite, verification tests on the M.V.A. 356 wing, and comparative tests of wing no. 36 at the Eiffel laboratory. The examination of all these experiments leads to the belief that, at large incidences, the speeds registered by the suction manometer of the testing chamber of the Eiffel laboratory wind tunnel are, owing to pressure drop, greater than the actual speeds. Therefore, the values of k(sub x) and k(sub y) measured at the Eiffel laboratory at large incidences are too low.

"The behavior of a liquid or gaseous medium, in which a solid body can move freely under the action of a force of constant magnitude and direction, is yet little known. Only in connection with a few special problems, which belong in this field, have experiments been tried and these chiefly concern technically important cases. The behavior of the simplest shaped bodies has as yet been scarcely investigated at all" (p. 1).

"This article resulted from the need of showing, in a simple way, how the aerodynamic properties of airfoils are affected by the shape of their profiles. No general solution of this problem could be found, since the profile shapes cannot ordinarily be expressed by simple mathematical formulas. This advantage is possessed only by the Joukowsky profiles and this discussion of the problem is therefore limited to them" (p. 1).

The author's first experiments with a glider on flight characteristics demonstrated that an accurate flight-path measurement would enable determination of the polar diagram from a gliding flight. Since then he has endeavored to obtain accurate flight measurements by means of kinetograph (motion-picture camera). Different methods of accomplishing this are presented.

The following report endeavors to show that aeromechanical experimentation has become an important aid to theory. Experiments can be tried with separate parts of airplanes or with models of whole airplanes, with propellers, and with anything else that comes into contact with moving air.

Engine conditions such as pressure characteristics, temperatures, and mechanical fatigue enable the employment of a criterion of general fatigue which simultaneously takes account of both mechanical and thermal conditions, for the sake of comparing any projected engine with engines of the same type already in use.

The present work investigates, on the basis of Prandtl's wing theory, the form of the lift distribution when the ailerons are deflected in opposite directions. An ideal fluid and a wing with a rectangular form are assumed. The moments must not cause any rotation of the wing or any deviation from the rectilinear motion.

Report discussing a demonstration was given within the last few days at the British Museum by Mr. J. W. Gordon, author of "Generalized Linear Perspective" (Constable and Co.), a work describing a newly-worked-out system by which photographs can be made available for the purpose of exactly recording the dimensions of the objects photographed even when the objects themselves are presented foreshortened in the photograph.

A history of English metal spar construction is presented in this paper. The way in which different spar designs or spar materials influence the aircraft wing loading and aerodynamics is described.

"On April 15, 1920, the under Secretary of State for Aeronautics and Aerial Transport decided to adopt as Standard Atmosphere for official airplane tests in France, the atmosphere defined by the following law, known as the Law of the S.T.You.(Technical Section of Aeronautics): From 0 to 11,000 m. - 0=15-0.0065 Z and above 11,000 m. - 0= -56.5 degrees being the temperature in centigrade degrees at altitude Z expressed in meters. For altitude 0 the pressure is 760 mm of mercury. In the magazine "L'Aeronautique" Mr. A. Toussaint has already written at length on the first studies which led to the elaboration of this law. Since that time the results obtained have been confirmed by fuller and more abundant data which have justified the official adoption of the Law of the S.T.Ae" (p. 1).

A formula for calculating the safety of airplanes is given and the stresses on airplane components are calculated. Some questions regarding the information obtained from the formula and its application to safe airplane design for pilots are provided.

The object of this work has been to construct an apparatus for obtaining oscillogram of voltages and currents which are variable with respect to time and of the frequency which is constantly met in radio.

The causes of the destruction of the Dixmude are discussed and some conclusions are drawn. The author believes a gasoline fire instead of a lightning strike was probably responsible, but the public believes otherwise.

The author recounts his experiments with helicopters. The object of his investigations was to remain stationary in the air for five minutes and to make a closed flight at low altitude. Some of the topics discussed include stabilization, horizontal flight, and directional control.

Wind-driven propellers are much used as sources of power for equipment such as radios. This report establishes the principles involved and acquaints the reader with rules for design of such windmills.

This report discusses the general considerations for the design of aerodynamic laboratories. The dimensions, construction, and components of the wind tunnel are given special attention.

A closer examination of Newton's formula for air resistance shows that it is well to consider the air as an ordinary fluid, and, indeed for most of the velocities considered, as a non-compressible fluid, so long as the dimensions of the moving body are large in comparison with the mean free path of the particles of air.

The future development of aerial navigation is closely connected with the condition of obtaining airplanes of great stability and sufficient strength. Different construction materials such as wood, aluminum, iron, and alloys are examined to determine which materials or combination of materials provides a greater coefficient of safety.

This report considers as the dominating characteristic, either the load carried, the speed, the radius of action, the fuel consumption, the activity of transport, or, lastly, the qualities of comfort and safety. The first four factors determine the theoretical efficiency, while the others determine its practical efficiency.

"Measurements made during flight with the triple recording device which gives the horizontal and vertical speeds of an airplane and the angle it makes with the horizon, render it possible to calculate its lift, its drag, and R the resultant of the action of the air both in magnitude and direction, but with these data alone, it is impossible to determine the position of this resultant in the plane of symmetry of the airplane. We will also see how we may determine the position of R during flight and then calculate the variations in the stability of an airplane" (p. 1).

This report examines the question of the responsibility of the carrier in air traffic. The French were concerned about the competitive advantage the English companies enjoyed because of differences in their respective laws.

The evolution of construction techniques and the use of metal in wings is presented. Drag is discussed along with the fuselage and tail. The interaction of these parts is also investigated.

In the present treatise, a convenient method will be indicated, which makes it possible to determine the polar curve of an airplane at short distances from the ground by a simple short calculation, when the polar curve is known for flight in unlimited space.