Report issued by the U.S. Bureau of Mines on sub-bituminous slack from Denver, Colorado. The characteristics and properties of 2-1/2 inch slack samples are listed. This report includes tables, graphs, maps, illustrations, and photographs.

Technical report. Three extractions of a diethyl ether solution of uranyl nitrate with small portions of water are effective in removing rare earths, as is shown by radio-gadolinium and radio-europium tracer experiments. A study of representative ethers, alcohols, ketones, and esters showed that diethyl ether and a mixture of 85% ethyl methyl ketone with 15% xylene are the best solvents for the extraction.

Bulletin presenting testing of a monocoque box with a stress-carrying door made and tested in torsion. The results indicate that if a stress-carrying door and its frame are made sufficiently heavy, the torsional stiffness of the box with the door can be made greater than the torsional stiffness of the box without the cut-out" (p. 1).

From General Analysis: "The purpose of part I of this paper is to show how the loading that gives the minimum induced energy loss can be obtained from rather elementary considerations and to present design charts from which such a plan form can be quickly obtained for any set of design conditions."

"A set of dimpling tools was designed for 0.040-inch 24S-T sheet and flush-type rivets 1/8 inch in diameter with 100 degree countersunk heads. The dimples produced under different conditions of pressure, sheet thickness, and drill diameter are presented as cross-sectional photographs magnified 20 times. The most satisfactory values for the dimpling tools were found to be: maximum punch diameter, 0.231 inch; maximum die diameter, 0.223 inch; maximum mandrel diameter, 0.128 inch; dimple angle, 100 degree; punch springback angle, 1 1/2 degree; and die springback angle, 2 degree" (p. 1).

"A graphical method is described for finding the shape (camber and twist) of an airfoil having an arbitrary distribution of lift. The method consists in replacing the lifting surface and its wake with an equivalent arrangement of vortices and in finding the associated vertical velocities. By a division of the vortex pattern into circular strips concentric about the downwash point instead of into the usual rectangular strips, the lifting surface is reduced for each downwash point to an equivalent loaded line for which the induced velocity is readily computed" (p. 1).

Report presenting testing of eighteen 24S-T aluminum alloy sheet-stringer panels in end compression under carefully controlled edge conditions. Results regarding the strains, deflections, failure, and buckling of the sheet are provided.

"Fatigue tests were made on some 1.375-inch-diameter and 0.300-inch diameter specimens of a 17S-T aluminum alloy rod. One test of a large specimen was run continuously to failure at a maximum stress of 22,000 pounds per square inch. In two other tests of large specimens, thin surface layers were removed periodically until failure occurred. The same nominal maximum stress of 22,000 pounds per square inch was used throughout the two tests and the load on the fatigue machine was lowered accordingly after the removal of each surface layer" (p. 1).

From Summary: "A 1/6-full-size model of the hull of the British Singapore IIC flying boat was tested in the NACA tank. The results are given in the form of charts and are compared with the results of previous tests made in the NACA tank of a 1/12-full-size model, published in NACA T.N. No. 580, and with the results of tests made in the British R.A.E. tank of another 1/6-full-size model of the same hull. When the data from the tests of the 1/6- and 1/12-full-size models were compared on the basis of Froude's law of comparison, differences were found."

This report presents the results of an investigation conducted on the effect of exhaust-stack nozzle area, shape, and length on engine power, jet thrust, and gain in net thrust (engine propeller plus jet). Single-cylinder engine data were obtained using three straight stacks 25, 44, and 108 inches in length; an S-shaped stack, a 90 degree bend, a 180 degree bend, and a short straight stack having a closed branch faired into it. Each stack was fitted with nozzles varying in exit area from 0.91 square inch to the unrestricted area of the stack of 4.20 square inches. The engine was generally operated over a range of engine speeds from 1300 to 2100 r.p.m, inlet-manifold pressures from 22 to 30 inches of mercury absolute, and a fuel-air ratio of 0.08. The loss in engine power, the jet thrust, and the gain in net thrust are correlated in terms of several simple parameters. An example is given for determining the optimum nozzle area and the overall net thrust.

Report presenting two series of diagonal-tension beams with double uprights tested to destruction while strain measurements were being made at a large number of points. On the basis of a revised formula, more than 100 tests made by five manufacturers were analyzed.

Report presenting a study of the performance of bombers powered by two, four, and six 3000-horsepower engines supercharged to 35,000 feet. The performances are computed and are based on drag coefficients equal to the best obtained on modern airplanes and on weight estimates obtained from modern Army Air Forces airplanes. A chart is provided with the coordinates of power loading and wing loading noted so that all performances can be compared.

Report presenting air-flow surveys made in the region of the tail plane of a typical twin-engine tractor monoplane model with tail surfaces removed. The surveys were made with propellers removed and operating and for both cases included the conditions for flaps retracted and flaps deflected 50 degrees.

Report presenting methods for determining the jet-boundary corrections to the downwash behind models in rectangular wind tunnels. The methods take into account the tunnel dimensions, the type of jet, the span loading of the model, the geometric position of the wind and of the tail in the tunnel, the displacement of the wing wake, and the effect of the slipstream.

Report presenting investigations of a full-scale air-cooled aircraft-engine cylinder of 202-cubic-inch displacement to determine the effects of internal cooling by water induction on the maximum permissible power and output of an internal-combustion engine. Results regarding the maximum permissible engine performance, engine temperatures, and constant inlet-air pressure investigations are provided.

Report presenting samples of 17S-T and 24S-T aluminum alloys subjected to accelerated corrosion tests in which the corrosion period was established at 6 hours for samples that had been etched to produce a uniform surface. The results indicate the types of corrosion attack, which are described in standard terminology, and may form a basis for estimating the resistance of the material to corrosion by a comparison of the relative depth and frequency of the corrosive attacks.

This technical report details a process in order to determine the densities of several uranium compounds.

Report presenting an investigation to determine whether the difference in the spanwise loading of the two types of aircraft were responsible for the differences in spin characteristics, particularly in regards to angle of attack.

Report issued by the U.S. Bureau of Mines discussing the construction of a vapor-pressure chart. A description of the vapor-pressure chart is presented. This report includes illustrations.

Report issued by the U.S. Bureau of Mines discussing the use of mineral pigments. The importance of pigments is presented along with a description of import and export trends of minerals. This report includes tables.

Report presenting an investigation conducted in the 19-foot pressure tunnel to determine the aerodynamic effects of several arrangements of external auxiliary fuselage and wing tanks of large fuel capacity on a fighter-type airplane. The rectangular tank arrangement of 350-gallon fuel capacity has the greatest adverse aerodynamic effect on the airplane and is the least desirable of all the configurations tested.

Report presenting the results of spin-tunnel testing of 65 models indicating that when a single-engine type airplane was simulated with mass distributed along the fuselage, the rudder was the predominant control for recovery. The primary focus of this investigation is to determine the spinning characteristics of the airplane and to develop a useful criterion for predicting the optimum control manipulation for recovery.

Supplement using data from a previous report to show the cargo that can be carried at various ranges, pounds of cargo that can be carried per pound of fuel, and other graphs to simplify the problem of determining which cargo can be carried at any range. The assumptions, parameters, and equations from the original report are carried over in the supplement.

Report presenting aerodynamic tests of a 300-pound M-31 demolition bomb. Force tests at a range of angles of attack were made at Mach number 0.725, which corresponds to a speed of 810 feet per second at sea level. Results regard the drag, lift, and pitching moment are provided.