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.

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.

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.

Various details of design or arrangement of the parts of airplane structures are shown and discussed, the use of these devices having resulted in the production of structures of adequate strength, yet of a weight less than one-half of the usual construction.

The following paper is based on the results of tests, upon duralumin columns, contained in two theses presented to the Department of Civil and Sanitary Engineering of the Massachusetts Institute of Technology.

"The logarithmic polar curve has for several years been used by the most prominent aerodynamical laboratories as well as by airplane manufacturers in Europe. To show more clearly the practical application of the polar curve, a series of examples are given with suggestions for solution. After a discussion of the theory and the practical application of the polar curve, the following problems are discussed: climbing flight, speed at various altitudes, and the characteristics of two seater observation airplanes of recent design" (p. 1).

A series of experiments were conducted related to the action of an airstream oscillating vertically on supporting surfaces. The object of the experiments was to verify the very interesting results of Mr. Katzmayr, Director of the Vienna Aerodynamics Laboratory, and, if possible, to obtain more complete data on the effect of the amplitude and velocity of the oscillations of the airstream. The results obtained by Mr. Katzmayr are briefly summarized. The conduct of the numerous experiments to verify his results are described in detail. Experimental results are given in tabular and graphical form.

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.

"This report deals with an investigation carried out in the Civil Engineering Laboratory of the University of California, to determine the accuracy of existing methods of computing the stresses in an airplane fuselage when subjected to torsion, and to derive a simple approximate formula for the rapid calculation of these stresses. The formula is derived by using the customary least work equation and considering each bay separately" (p. 1).

The first section deals with the theoretical side of statical stability of airships in general. The second section deals with preliminary tests of the model and experiments for the determination of effects due to change of tail area, aspect ratio, tail form, and tail thickness.

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.

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.

"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).

"The effect of an aileron displacement on the distribution of the lift along the span is computed for an elliptic wing of aspect ratio 6 for three conditions. The lift distribution caused by the aileron displacement is uniform and extends normally beyond the inner end of the ailerons. Hence, the displacement of an aileron with constant chord length may bring about passing the stalling point of the adjacent wing sections, if these were near this point before" (p. 1).

"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).

These tests were undertaken to find the effect of turbulence in the air stream upon the lift and drag forces measured on models in the four-foot wind tunnel at the Massachusetts Institute of Technology. Maximum lifts and minimum drags were measured on Gottingen-387 and R.A.F.-15 airfoils, minimum drag on a streamlined strut, and the static pressure gradients for different conditions of turbulence were investigated. The results show that the scale of the turbulence (as defined in this report) has a marked effect upon the measured forces on models tested in the tunnel as well as on the pressure gradient, and it is recommended that further investigation of the phenomena be made with the aid of smoke and small wind vanes.

This note investigates the effect of high altitude or low atmospheric pressure upon the operation of an engine and the effect of the low pressure and lack of oxygen and of the very low temperatures upon the pilot and upon the performance of the airplane itself.

A simple and easily applied method of calculating the dimensions and horsepower necessary for an airship to have any given performance is described and illustrated by examples. The method includes means for estimating the changes in performance or in size when modifications or new features are introduced into a design, involving increase or saving in weights, or changes in resistance or propulsive efficiency.

"This note, prepared for the National Advisory Committee for Aeronautics, contains the demonstration that the pressure around the circular cross section of an elongated airship, plotted against the diameter of symmetry, can be expected to be represented by a straight line" (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).

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.

"The following considerations determine the strength of airplane fabrics: 1. maximum air forces acting on the surfaces (including local stresses); 2. tensions produced in the fabrics, in the directions of both warp and filling; 3. factor of safety required. The question of the permissible depression of the fabric as affecting the aerodynamic requirements in regard to the maintenance of shape of the section, the tenacity and extensibility of the layer of dope, its strength and its permeability to water is almost as important" (p. 1).