Report issued by the U.S. Bureau of Mines on the engineering and production methods of the Oklahoma City oil wells. Characteristics and properties of the wells, and methods and practices of well engineering are presented. This report includes tables, graphs, maps, and illustrations.

Report issued by the U.S. Bureau of Mines on the oxidation levels caused from different oil recovery processes. Experiments were conducted to determine the effect of air on crude oil, and the degree of oxidation. This report includes tables, and a map.

"Extensive strain-gage measurements were made chiefly on the tension side of five small rectangular box beams constructed of sheet duralumin. The main conclusion was that within the test range the tension cover may be considered as being fully effective but that at any given point on the beam there may be unaccountable variations of 5 percent from the calculated stresses on the thicker sheets tested (0.044 and 0.023 inch) and of 10 percent or more on the thinnest sheet tested (0.014 inch)" (p. 1).

"The effect of tapered ailerons on linearly tapered wings is theoretically determined. Four different aileron spans are considered for each of three wing aspect ratios and each of four wing taper ratios. The change in lift on one half of the wing, the rolling moment, the additional induced drag, and the yawing moment, due to aileron deflection, are represented by non dimensional coefficients" (p. 1).

"The hydrodynamic characteristics of a model of the hull of the Short Calcutta (N.A.C.A. Model 47) are presented in non-dimensional form. This model represents one of a series of hulls of successful foreign and domestic flying boats the characteristics of which are being obtained under similar test conditions in the N.A.C.A. tank. The take-off distance and time for a flying boat having the hull of the Calcutta are compared at two values of the gross load with the corresponding distances and times for the same flying boat having hulls of two representative American types, the Sikorsky S-40 and the N.A.C.A. 11-A" (p. 1).

Report issued by the U.S. Bureau of Mines discussing the mineral production of mines in Kern County, California. Mining and milling methods of these mines are presented. This report includes tables, maps, illustrations, and photographs.

This report begins by indicating several simple principles concerning the velocity distribution over the blades of a lifting propeller of diameter D, revolving at n revolutions per second, and animated by a horizontal movement of translation at speed V. The calculation, compared with the test data, has shown that the aerodynamic action of the air on the blades depends almost only on the velocity components in a plane at right angles to the blade span. A history of gyroplane and gyrocopter development is presented as well as the advantages in using both types of craft.

Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel to determine the aerodynamic properties of tapered wings having partial-span flaps for high lift and ordinary ailerons for lateral control. Each of two Clark-y wings, tapered 5:1 and 5:3, was equipped with partial-span split flaps of two lengths and with ordinary ailerons extending from the outboard ends of the flap to the wing tips. Measurements of wing forces and moments and of aileron hinge moments were made for the two conditions of flaps neutral and deflected.

From Summary: "An analysis is made of the influence on autogiro rotor characteristics of a periodic blade twist that varies with the azimuth position of the rotor blade and the results are compared with experimental data. The analysis expresses the influence of this type of twist upon the thrust, torque, and flapping motion of the rotor. The check against experimental data shows that the periodic twist has a pronounced influence on the flapping motion and that this influence is accurately predicted by the analysis. The influence of the twist upon the thrust and torque could be demonstrated only indirectly, but its importance is indicated."