This report provides a critical discussion of the results of the experiments conducted in the previous NACA-TM's 329 and 330. The main object of this investigation was to determine the size of the drops in mechanical atomization.

Report discussing economic and design characteristics are examined in the design of airplanes and airships.

Memorandum describing the method of determining the pressure distribution on the fuselage, with special attention to how it is affected by the presence of the wings.

Reproduction of thirteen graphs for computing compressibilities of various gases and for computing the volumes delivered from cylinders containing various gases.

This report deals mainly with the methods of construction employed when after the plan had been approved. The foundation, side walls, doors and roof are all discussed and the economic savings resulting from this method of construction.

This report details the contest to design and build concrete airship hangers. The difficulty lies in the magnitude of the absolute dimensions. An airship shed must withstand two principal types of stresses: those resulting from its own weight and those due to the wind. This report discusses both problems in detail.

The following pages present a review of the air transportation activities of England, France, Germany and Holland, based on an inspection trip during the summer of 1924. The different components described include operating companies, nature of transportation services, air traffic, flying equipment, government relations, and general remarks.

"The object of this article is to set forth the particular properties of swiftly-moving air, how these affect the installation of a wind tunnel, the experimental results already obtained, the possible applications of such a tunnel, and what can be easily accomplished at the present time" (p. 1).

The designing of an airplane requires an accurate knowledge of the aerodynamic properties of its wings, as expressed in the polar diagram. It is important to continue the theoretical researches on the aerodynamic phenomena of wings, in order to determine by calculation, their fundamental characteristics and to increase and formulate our knowledge in this field.

The stressing of an airship depends on three nonuniformly distributed forces: air forces; the distribution of acceleration forces; and how the air pressure is distributed on the hull. This report examines the stresses and comes to conclusions on the size of airships.

Suggestions are presented for the establishment of lecture courses on aviation. An outline of some courses that have previously been given is provided.

Report issued by the Bureau of Mines over the production methods and uses of plastic magnesia. Methods, properties, and uses of plastic magnesia are discussed. This report includes tables, illustrations, and photographs.

The hydrodynamics and mathematical models as applied to the potential flow about a Joukowski wing are presented.

Results are presented of the theory of wings and of wing sections which are of immediate practical value. They are proven and demonstrated by the use of the simple conceptions of kinetic energy and momentum only.

The technical staff of the NACA at Langley Field, has made a series of free flight tests with a JN4h airplane in order to find the best place for an instrument for measuring the angle of attack. A "neutral zone" was found where the air remains either at rest relative to the undisturbed air beyond the influence of the airplane, or is set in motion parallel to the motion of the airplane. This zone is about midway between the two wings and slightly in front of, or at the vertical plane through the leading edges of the wings but the exact position as well as the outlines of the zone varies considerably as the conditions of flight change.

Flight tests to determine lift and drag characteristics are discussed. A review is given of the fundamental principles on which the tests are based and on the forces acting on an airplane in the various conditions of steady flight. Glide with and without propeller thrust and the relation between angle of attack and the indicated airspeed for different conditions of steady flight are discussed. The glide test procedure and the problem of the propeller are discussed.

In recent tests on the pressures occurring on the envelope and control surfaces of the naval airship C-7, it was noted that the pressures on the nose of the airship, while flying in level circling flight, were symmetrically distributed. Such a condition can only occur when the nose of the airship is pointed directly into the wind, and to accomplish this in circling flight, the axis of the airship must then be parallel to the direction of the motion of the nose. The question was raised as to whether the same conditions occur generally on all airships in circling flight.

"This note shows that the main part of the discrepancy between full flight propeller performance and the performance of models in a wind tunnel is due to a scale effect, and that a minor part is caused by body interference. Analyses are made of propeller performances on several standard airplanes, and the actual brake horsepower compared with the power as calculated from model test data. The calculated power is based on that absorbed by a wind tunnel propeller model which is geometrically similar to the full scale propeller and is operating under the same ratio of V/nD" (p. 1).

Note presenting an exploration of the calculation of wing float displacement in single-float seaplanes. An explanation of a formula that can be used is provided.

"A formula for the computation of the vertical velocity component on all sides of an airplane is deduced and discussed. The formation is of value for the interpretation of such free flight tests where two airplanes fly alongside each other to facilitate observation" (p. 1).

Report containing information on the air forces on a wing produced by its pitching at a finite rate of angular velocity. The condition of smooth flow at the region of the trailing edge is maintained. The wing then experiences the same lift as if moving with the momentary velocity of the rear edge.

Calculations of the magnitude of the correction factors and the range of their variations for wind tunnel models used in making aircraft performance predictions were made for 23 wind tunnel models. Calculated performances were compared with those actually determined for such airplanes as have been built and put through flight test. Except as otherwise noted, all the models have interplane struts and diagonal struts formed to streamwise shape. Wires were omitted in all cases. All the models were about 18 inches in span and were tested in a 4-foot wind tunnel. Results are given in tabular form.

Three groups of airfoils have been tested in the variable density wind tunnel. The first group contains three airfoils. The second group is a systematic series of twenty-seven airfoils. The third group consists of several frequently used wing sections.

Following a curved path increases the distance to be flown, and a type of radio navigation that forces the adoption of such a path is therefore less efficient than one that marks out a definite straight line between the point of departure and the intended destination, and holds the airplane to that line. To determine the loss of efficiency resulting from curvature of the path, calculations were made for two particular cases by the method of step-by-step integration. The calculations were based on the assumption that the pilot makes straightforward use of his radio for navigation and makes no allowance for drift.