Report issued by the U.S. Bureau of Mines covering the crude oils from different regions of Texas. Analysis of the properties of each oil sample from the different regions of the state are presented. This report includes tables, and a map.

The results of a complete test in the N.A.C.A. tank on a model of the hull of Sikorsky S-40 flying boat ('American Clipper') are reported. The test data are given in tables and curves. From these data non-dimensional coefficients are derived for use in take-off calculations and the take-off time and run for the S-40 are computed. The computed take-off time was obtained by the Sikorsky Aviation Corporation in performance tests of the actual craft.

"So long a time was required for the disturbed water to become quiet after a model had been towed down the N.A.C.A. tank, that only 12 to 18 runs a day could be made. In order to shorten the time lost in waiting between runs, several different methods of suppressing the waves were tried. The most effective form of wave suppressor developed consists of wooden frames covered with fine copper screening and secured horizontally just beneath the surface of the water at the sides of the tank" (p. 1).

"The effect on engine performance of variations in the shape of the prechamber, the shape and direction of the connecting passage, the chamber volume using a tangential passage, the injection system, and the direction of the fuel spray in the chamber was investigated using a 5 by 7 inch single-cylinder compression-ignition engine. The results show that the performance of this engine can be considerably improved by selecting the best combination of variables and incorporating them in a single design. The best combination as determined from these tests consisted of a disk-shaped chamber connected to the cylinder by means of a flared tangential passage" (p. 1).

From Summary: "The investigation described in this report was made to determine the change in aerodynamic forces and moments produced by split flaps in a steady spin. The test were made with the spinning balance in the NACA 5-foot vertical wind tunnel. A low-wing monoplane model was tested with and without the split flaps in 12 spinning attitudes chosen to cover the probable spinning range. The results obtained indicate that the use of split flaps on an airplane is unlikely, in any case, to have much beneficial effect on a spin, and it might make the spin dangerous."

The rules and regulations for the International Touring Competition are presented as well as the technical characteristics that proved advantageous for the successful competitors.

The most important factors in evaluating performance of gliders are minimum sinking speed and minimum gliding angle. To assure their optimum value the energy necessary for flight, that is, the energy of lift and friction must be kept very low, or in other words, weight and total drag which have a decisive effect on the sinking speed and on the gliding angle, must be kept to a minimum. How great the effect of a reduction of these two quantities will be shown in the following.

This report presents the results of cooling tests conducted on a calibrated GR-1535 Pratt and Whitney Wasp, Jr. Engine installed in a Vought X04U-2 airplane. The tests were made in the NACA full-scale tunnel at air speeds from 70 to 120 miles per hour, at engine speeds from 1,500 to 2,600 r.p.m., and at manifold pressures from 19 to 33 inches of mercury absolute. A Smith controllable propeller was used to facilitate obtaining the different combinations of engine speed, power, and manifold pressure.

This report presents the tests results of a series of tests made of the sprays from 14 fuel injection nozzles of 9 different types, the sprays being injected into air at atmospheric density and at 6 and 14 times atmospheric density. High-speed spark photographs of the sprays from each nozzle at each air density were taken at the rate of 2,000 per second, and from them were obtained the dimensions of the sprays and the rates of spray-tip penetration. The sprays were also injected against plasticine targets placed at different distances from the nozzles, and the impressions made in the plasticine were used as an indication of the distribution of the fuel within the spray. Cross-sectional sketches of the different types of sprays are given showing the relative sizes of the spray cores and envelopes. The characteristics of the sprays are compared and discussed with respect to their application to various types of engines.

"This report presents a discussion of longitudinal stability in gliding flight together with a series of charts with which the stability characteristics of any airplane may be readily estimated. The relationships governing stability characteristics are derived from equations of equilibrium referred to moving axes that are tangent and perpendicular to the instantaneous flight path. It is shown that instability of the motion can arise only through an increase of linear and angular momentum in the system during one complete cycle" (p. 289).

Flight tests were made on PCA-2 autogiro with wing settings of 2.2 degrees, 0.9 degrees, and -0.5 degrees. The wing load and rotor speed were measured in steady glides. The results obtained show that a wide variation in rotor speed as a function of air speed can be obtained by a suitable adjustment of the wing setting; that by decreasing the wing setting the upper safe flying speed, determined by the decrease is rotor speed, is greatly increased; and that the interference of the wing on the rotor thrust and lift coefficients is negligible.

Report discussing the speed distribution in a laminar boundary layer on the surface of an elliptic cylinder, of major and minor axes 11.78 and 3.98 inches, respectively, has been determined by means of a hot-wire anemometer. The direction of the impinging air stream was parallel to the major axis. Special attention was given to the region of separation and to the exact location of the point of separation. An approximate method, developed by K. Pohlhausen for computing the speed distribution, the thickness of the layer, and the point of separation, is described in detail; and speed-distribution curves calculated by this method are presented for comparison with experiment.