Memorandum presenting an overview of the development of aeronautical industries and commercial aircraft as well as some of the problems that are resulting from it. Details of the aeronautical budget in various countries, organization of the air service, material exports, and airline operations are provided.

Note presenting methods for ascertaining the value of n in Euler's simplified formula, which can be used for the compressive strength of tapered airplane struts, by estimating from curves and by calculation.

Methods are here given for ascertaining the value of n in Euler's simplified formula, P = n (EI/l(sup 2)), for the compressive strength of tapered airplane struts, by estimating from curves and by calculation.

Note presenting some information on the effect of changes in the loading and in the disposition of the supporting framework on the covering fabric. The magnitude of the air forces to be taken into account and the corresponding factors of safety to be expected will be covered in a future report. Tables regarding some of these fabric characteristics are provided.

Factors of safety serve three purposes: provides against trouble arising from unexpectedly large loads, allows for imperfections of workmanship, represents a depreciation allowance. A consideration of these safety factors is provided in this report.

Described here is wing cutting equipment for the economical production of metal wings for wind tunnel models. The machine will make any size of constant-section wing or strut up to one-sixth inch chord by 36-inch span and up to a thickness of one and one-quarter inches. It cuts a smooth, true model that is accurate to within two-thousandths of an inch on any ordinate. The holding jaws are so designed as to leave the model free of chip marks, and the only hand finishing necessary after the cutting is a rub with amunite to remove burrs. The actual change on ordinate in this finishing rub is less than .0002 inches.

"In the slipstream behind a propeller there is a considerable amount of kinetic energy which has been imparted to it by the engine without producing any corresponding propeller thrust. The increased absorption of power reduces the propeller efficiency. Attention has been previously directed to this question by Bendemann and Madelung and other writers. Their contribution serves to verify a simple method of calculating the reduction in the propeller efficiency due to the slip stream" (p. 1).

"For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine" (p. 1).

"The vertical distribution of the pressure, temperature, and density of the atmosphere varies from day to day. Thus, rates of climb on different days cannot be compared directly, but must be corrected with reference to a standard rate of diminution of air density with increasing altitude. The following problem, therefore, has to be solved" (p. 1).

This article presents a discussion of the relative merits between monoplanes and biplanes. A comparison of the aerodynamic qualities and advantages of both types are provided.

Memorandum presenting a method of calculating the dead reckoning in aerial navigation.

Different aspects of an airship line between Lisbon and Rio de Janeiro are presented. Some of the factors discussed are: the number of passengers, fuel consumption, design, itinerary, airports, flight times, and income.

Memorandum presenting the history and development of airships. Tables containing information and statistics regarding some of the current airships are provided.

Memorandum presenting the rules and regulations of the Endurance Contest of Aviation Engines, which was put on by the Aero Club of France. A description of the rules regarding the aircraft in competition, the characteristics of the tests that were conducted, and information regarding classification of the aircraft is provided.

Static soaring flight has hitherto been accomplished by means of two sources of energy: ascending air currents in the vicinity of obstacles and those produced by unequal heating. The latter has not yet been practically tested in soaring flight.

In making tension tests, the slippage of the joints was noted at three points across each joint. In addition, stress strain curves were obtained for plain tension specimens, and a chemical analysis was made of the sheet.

In the first series of wind tunnel tests, the drag and cross wing force of all the struts were measured at a wind speed of 30 mph and at angles of yaw from 0 degrees to 20 degrees. To determine the magnitude of the VL effect, each strut was tested at zero yaw and at a series of speeds ranging from 15 to 38 mph. Although designed as fairings for cables, part of these sections gave such high crosswind forces that they seemed to have possibilities as airfoils.

Note presenting a consideration of the effect on engine performance of a known inequality of distribution. A measure of perfect distribution is provided and some of the factors that influence the unequal distribution of power among cylinders.

"The strength and reliability of airplanes depend greatly on the careful design and manufacture of fittings, couplings, and other highly stressed parts. The more important parts of the airplane must be occasionally tested for increased loads and in order to avoid the possibility of defects creeping in during subsequent production. Strength tests are discussed for fittings for wing spar joints, fittings for strut connections, internal bracing, control gear, and landing gear" (p. 1).

In this paper the application of the slip curve method to the design and analysis of windmills is discussed and illustrated by example.

Note presenting a graphic method for calculating the speed and climbing ability of airplanes. This method starts from the actual power developed by the engine and makes it possible to determine all factors which together constitute what are known as flight performances for any combination of engine and airplane from the single graphic diagram given.

The equilibrium, in still air, of a "stationary" helicopter (i.e., of one having neither vertical nor translational velocity, but a tendency to remain practically motionless within restricted limits of space) presents some difficulty in practice and justifies a theoretical investigation of its "inherent stability," i.e., independent of the pilot.

Report presenting a description of a parachute design contest. The object of this contest was to obtain a parachute of light weight and small bulk, suitable for airplanes. The primary areas of focus were safety, ability to be installed on airplanes, speed, materials, and behavior of the parachutes in the air.

This paper constitutes a general theoretical discussion of the damping factor in roll, together with the results of wind tunnel tests on the continuous rolling of U.S.A. 30 airfoil.