This report presents a clearer understanding of Helmholtz's work on the calculation of waves along the separation of two different liquids.

"This note contains the results of tests to determine the resistance of four sizes of streamline wire. The investigation was conducted in the six-inch wind tunnel of the National Advisory Committee for Aeronautics. The tests were made at various velocities and it was found that the resistance of streamline wires was considerably less than that of round wires of equivalent strength. Scale effect was also found since, with an increase of Reynolds Number, a decrease in the resistance coefficient was obtained" (p. 1).

"The work presented in this report was undertaken at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics to determine a suitable method for measuring the maximum pressures occurring in aircraft engine cylinders. The study and development of instruments for the measurement of maximum cylinder pressures has been conducted in connection with carburetor and oil engine investigations on a single cylinder aircraft-type engine. Five maximum cylinder-pressure devices have been designed, and tested, in addition to the testing of three commercial indicators" (p. 311).

This report describes and develops methods by which the aerodynamic characteristics of an airfoil may be calculated with sufficient accuracy for use in airplane design. These methods for prediction are based on the present aerodynamic theory and on empirical formulas derived from data obtained in the N. A. C. A. variable density wind tunnel at a Reynolds number corresponding approximately to full scale. (author).

Report presenting a discussion of the laws of motion of a fluid with very low viscosity. Mathematical formulas that have been created in order to compensate for this lack of viscosity and the circumstances under which viscosity can be disregarded are provided.

For good profiles the profile-drag coefficient is almost constant in the whole range which comes into consideration for practical flight. This is manifest in the consideration of the Gottingen airfoil tests and is confirmed by the investigations of the writer (measurements of the profile drag during flight by the Betz method), concerning which a detailed report will soon be published. The following deductions proceed from this fact. The formulas developed on the assumptions of a constant profile-drag coefficient afford an extensive insight into the influences exerted on flight performances by the structure of the airplane.

The reliability of the assumption of a parabolic shape of the polar curve is investigated and found satisfactory for all practical purposes. It is further shown that the aerodynamically best possible or "ideal" airplane is produced on this assumption. Lastly, detailed suggestions are given on the possibilities of application of this method of calculation. It especially simplifies the design and evaluation of structural changes and the determination of the limits of technical possibilities. The present report deals only with the relations of the airfoils. The mutual action of the airfoils, engine and propeller will be treated in a subsequent report.

The report discusses the problem of rating the various seaplane designs from the 1926 seaplane contest. The whole process of rating consists in measuring the climbing speed, flying weight and carrying capacity of a seaplane and then using these data as the basis of a construction problem.

The tests described in this paper afford a direct comparison of the efficiency and smoothness of flow obtained with propeller fan and multiblade centrifugal fan drives in the same wind tunnel. The propeller fan was found to be superior to the centrifugal fan in that the efficiency was about twice as great, and the flow much smoother.

Measurements of drag were made on fittings taken from a typical fuselage to determine whether the difference between the observed full size fuselage drag and model fuselage drag could be attributed to the effects of fittings and surface irregularities found on the full size fuselage and not on the model. There are wide variations in the drag coefficients for the different fittings. In general those which protrude little from the surface or are well streamlined show very low and almost negligible drag. The measurements show, however, that a large part of the difference between model and full scale test results may be attributed to these fittings.

Circular describing the Glouster IV, which is a biplane designed for high maximum speeds. A description of the components, design, controls, performance, drawings, and photographs are provided.

The Calcutta is a large seaplane, with seating for 16 and a payload of 3,400 pounds. A description of the design, construction features, engine installation, specifications, performance, and photographs are provided.

The S.5 is equipped with Napier Lion racing engine, all duralumin floats and has a top speed in excess of 300 M.P.H. A description of its design, flight characteristics, and some photographs are provided.