In the following note, prepared for the National Advisory Committee for Aeronautics, this induction factor is determined from the result of a model test, and compared with a formula recently developed by the author. The two results are found to be in substantial agreement.

Report presenting some theoretical calculations for determining the problems of accelerated and disturbed motion, phenomena in an accidental or intentional disturbance through the deflection of the rudder or elevator, or any other change in the conditions of flight.

'Experiments similar to those carried out with the A.E.G (Allgemeine Elektrizitats-Gesellschaft) were made in the small wind tunnel of the Gottingen laboratory on a model of the D.F.W. airplane T-29. Three series of tests were carried out on the model with a velocity head (or dynamic pressure) of 5 kg/sq m (1.02 lb/sq ft), during which one of the movable surfaces was deflected at various angles, while both the others were retained in their central positions. Of special interest among the results of the tests is the different run of the elevating moments" (p. 1).

Note presenting an investigation of curvilinear flight, which is defined as steady horizontal flight in a circle in which no side slip occurs. The investigation occurred under very specific circumstances and rests on two basic assumptions, which are that the airplane lies correctly in the turn so the resultant of gravity and centrifugal force falls in the plane of symmetry and that the airplane must lie in the turn so that the axis coincides with the direction of motion.

"Dihedral and sweep back can properly be compared only to the extent to which their action is similar in a side slip. In general the rolling moments due to side slip are about three to six times greater for a given dihedral angle than for an equal angle of sweep back" (p. 1).

"These experiments were carried out to determine the aerodynamic characteristics of various triplanes, which differed in the relative positions of the wings and, more especially, in the stagger, and in the shape of the wing sections. The tests were restricted to such dispositions as appeared constructively adapted to the plan form considered. Four different sets of wings were used in these tests, three of which had the same cross-section but differed in aspect ratio and in area" (p. 1).

"This investigation was made at the request of the Bureau of Aeronautics. Since the ordinary torsion formula is based on elastic resistance to deformation, it is inaccurate for determination of ultimate stresses in thin wall tubing subjected to torsional loads. It has been found that the torsional modulus of rupture varies with the ratio of diameter to gage thickness and the object of these tests was to determine the extent of these variations for subject materials. This is somewhat of a prorogation of work done by the Army Air Service at McCook Field" (p. 1).

"The present contribution is the sequel to a paper written by Messrs. R. Fuchs, L. Hopf, and H. Hamburger, and proposes to show that the methods therein contained can be practically utilized in computations. Furthermore, the calculations leading up to the diagram of moments for three airplanes, whose performance in war service gave reason for complaint, are analyzed. Finally, it is shown what conclusions can be drawn from the diagram of moments with regard to the defects in these planes and what steps may be taken to remedy them" (p. 1).

"This note has been prepared for the National Advisory Committee for Aeronautics. It deals with the model rules relating to aeronautical problems, and shows how the characteristics of one airplane can be determined from those of another airplane of different weight or size, and of similar type. If certain rules for the ratios of the dimensions, the weights and the horsepower are followed, a small low-powered airplane can be used for obtaining information as to performance, stability, controllability and maneuverability of a larger prototype, and contrariwise" (p. 1).

"During some tests of a one-cylinder engine, using gas oil (diesel engine oil, specific gravity 0.86 at 60 F) with solid injection and compression ignition, it was found to be necessary to increase either the jacket water temperature or the compression pressure in order to start the engine. It was found that a sufficient increase in compression pressure could be obtained simply by attaching a long pipe to the inlet flange of the cylinder. However, since no data were available giving the values of the increase in compression pressure that might be expected from such a step-up, an investigation was made covering some engine speeds between 500 r.p.m. and 1800 r.p.m." (p. 1).

Note presenting a general method followed to simplify the numerical work in hydrodynamics, which consists of neglecting quantities of a lower order of magnitude. Four of the solutions covered in this report include the theory of the lateral air forces on airship hulls, theory of wing sections in a two-dimensional flow, theory of wings with a finite span, and propeller theory.

"This note, prepared for the National Advisory Committee for Aeronautics, contains a discussion of the pressure distribution over ellipsoids when in translatory motion through a perfect fluid. An easy and convenient way to determine the magnitude of the velocity and of the pressure at each point of the surface of an ellipsoid of rotation is described. The knowledge of such pressure distribution is of great practical value for the airship designer" (p. 1).

"This note, prepared for publication by the National Advisory Committee for Aeronautics, is a collection of the tables of the factor of apparent mass that have been published up to now. The theory of the motion of solids in a perfect fluid is of the greatest value for the study of most aerodynamic problems, and the additional apparent mass of an immersed solid is the most important characteristic for such theoretical numerical computations. It will therefore be helpful to have the most important values of the apparent mass - for some elementary cases - collected in a convenient form" (p. 1).

Here, values for tension, compression edgewise of laminations, and transverse flatwise of laminations are given for Micarta made with various kinds of sheet material. The corresponding values for white oak are given for comparison. It was found by destructive and service tests that Micarta made with a good grade of cotton duck will give satisfactory service with most designs.

The methods used in manufacturing Micarta propellers differ considerably from those employed with wood propellers on account of the hardness of the materials. The propellers must be formed accurately to size in a mold and afterwards balanced without the customary trimming of the material from the tips. Described here are the pressing and molding processes, filing, boring, balancing, and curing.

Tests were made in the no. 1 (5 ft. atmospheric) wind tunnel at Langley Memorial Aeronautical Laboratory to determine the air forces acting on rotating cylinders with axes perpendicular to the direction of motion. Two cylinders were tested, one with a circular cross-section and the other with a Greek cross. The cross cylinder and compound strut were found to not be as efficient as the circular one.

The design of propellers made of Micarta is discussed. The advantages of the material are noted, especially as compared with wood. The design changes necessitated by the use of Micarta are discussed with reference to the hub boss, the narrowing of the blade tips, the thinning of the blades, the angles of the leading and trailing edges, and the adjustment of the pitch. Results of flight tests show that the Micarta propeller gave a top speed of 2 miles per hour more than the wooden propeller while turning about 120 r.p.m slower, with about the same rate of climb.

Note presenting a description of the aviation testing laboratory that has been built at the Bureau of Standards in order to test aviation engines under approximate engine conditions. A description of some of the calculations that are used to compare experimental and theoretical results are provided.

A description is given of the methods used in design of Micarta propellers. The most direct method for working out the design of a Micarta propeller is to start with the diameter and blade angles of a wooden propeller suited for a particular installation and then to apply one of the plan forms suitable for Micarta propellers. This allows one to obtain the corresponding blade widths and to then use these angles and blade widths for an aerodynamic analysis.

These new regulations are intended to replace those of November 1, 1922, and give the directions to be followed in the supervision of aircraft by the agents of the Aeronautical Section of the Bureau Veritas. The rules consist of four sections: rules regarding an aircraft leaving a repair shop, the objects of quarterly and weekly inspections, and rules regarding the upkeep and repair of airplanes.

Report presenting an exploration of the concept that the ratio between the volume and the surface area also exerts an influence on other secondary characteristics of airships.

Differential and integral curves are presented and well as numerous calculations relating to hulls. Some of the calculations include those relating to hulls, those relating to the invariability of the shape of the hulls, and those relating to the suspension of the hull.

This airship was built by the Zeppelin Airship Company at Friedrichshafen in 1923-4, for the United States Navy, as the reparations service of the German Government in fulfillment of the treaty of peace. A description of the design, components, flight characteristics, blueprints, and photographs are provided.

The knowledge gained from previous experiments and reports was utilized for the construction of a dynamometer hub for 200 mkg (134.4 ft.-lb.) and 1200 kg (2646 lb.) thrust suited for a Liberty "12" engine. A reversing device is also described.