Report issued by the U.S. Bureau of Mines on the annual work conducted by the Mining Division during 1942. Descriptions of projects and operations during the fiscal year are listed. This report contains tables, and photographs.

This report follows a study that deals with a portion of the ternary diagram previously analyzed, namely the boundary curves which separate the central area of two coexistent liquid phases from the two border stripe representing one-phase liquid systems.

Report presenting an investigation in the 7- by 10-foot tunnel of various modifications to the trailing edge of a 0.155-chord plain aileron on a semispan model of the tapered wing of a fighter airplane. The stick forces and rates of roll were estimated for a fighter airplane with the plain and modified ailerons.

Report presenting data pertaining to forces and moments developed by V-bottom planing surfaces of different angles of dead rise in order to compute the effect of dead rise on the lower trim limit of stability on a seaplane. Increase of angle of dead rise in the range of 10 degrees to 30 degrees causes an important increase in the lower limit of stability.

Report presenting a report regarding the basic factors of heat transfer applied specifically to aircraft heating and to guide the experimenter in planning experiments to obtain further data.

Report presenting the properties of some exhaust gases and air that are pertinent to airplane heat transfer calculations, including air, hydrogen, nitrogen, oxygen, carbon dioxide, and carbon monoxide. A bibliography related to gas properties is also provided.

Report presenting a study of two double tube cylindrical heat exchangers, in which hot exhaust gases pass through the annular space and ventilating air passes through the center tube, to determine heat transfer performance and pressure drop. Tests were performed in order to establish a simple, accurate method of predicting the performance of the double tube heat exchanger, to compare the performance of the straight and dimpled tubes, and to determine the pressure drop across the units.

Report presenting a study of two double tube, cylindrical, longitudinally finned heat exchangers in which hot exhaust gases pass through the annular space and ventilating air passes through the center tube in order to determine heat transfer and pressure drop performance.

Report presenting flight tests to determine whether a towed body that was designed to meet certain specifications met the stability specification, which required that angular deviations in flight should be less than 1 degree. The requirement was met in flight in smooth air, but not in rough air, where the rolling motions were considerably larger.

Bulletin presenting an investigation conducted to determine the effect of countersunk depth on the tightness of two types of machine-countersunk flush rivet. The specimens tested in the study were simple lap joints made by two different riveting methods. The results indicated that roundheaded rivets inserted from the back of the joint with the countersunk heads formed int he driving of the rivets produce tighter joints over a large range of depths than ordinary flush rivets.

Report presenting an investigation of the performance of a two-stage turbosupercharger with mixed-flow impellers. Two complete superchargers were tested; both were the same except for modified vanes in the interstage passage and a slightly different first-stage diffuser shape. The modified supercharger performed slightly better than the original, but both showed good characteristics over a range of operating conditions.

Note presenting the results of an investigation on the distribution of stress in a plate elastically supported along two edges and subjected to compressive loads in a direction parallel to the elastically supported edges. A theoretical calculation was carried out in which the influence of the elastic support was taken into account.

"The data are presented in coefficient form and include lift, drag, and pitching-moment coefficients of the airfoil-flap comoinations and the normal-force, chord-force, and hinge-moment coefficients of the upper (perforated split) flap and lower (slotted) flap" (p. 1).

"Data from wind-tunnel measurements of elevator hinge-moment coefficients at high angles of attack are utilized in estimating elevator stick forces in spins. The analysis indicates that elevator forces on several current airplanes will be so high that the pilot will be unable to push the stick to the neutral position. Large nose balances involve danger of the elevator locking in the full-up position" (p. 1).

Report presenting testing in the two-dimensional turbulence tunnel of a model of the tip section of the wing of the XP-63 airplane. Several alterations of the skirts and balance on the internal-balance aileron were tested to obtain various aerodynamic characteristics of the aileron.

Report presenting a calculation of the load over an elliptical wing with 30 degrees sweepback by a method, based on vortex theory, which takes account of the chordwise distributions of lifting area. The theory indicates a 14-percent loss in total lift due to the introduction of sweepback, with the greatest loss taking place at the center of the span.

"Strain-gage tests were made on two box beams loaded to destruction in an attempt to verify the shear-lag theory at stresses beyond the yield point. The test results indicated that the corner-flange stresses can be predicted with a fair degree of accuracy. Collapse of both beams was precipitated by failure of the corner angles at stresses close to the column yield stress of the material" (p. 1).

Report presenting an investigation of rudder trim force change with speed and power, rudder force reversals in sideslips, and rudder positions in sideslips and straight flight of a P-40E airplane. Quantitative measurements of the items were made on three other vertical arrangements.

From Summary: "A pursuit type airplane encountered severe diving moments in high-speed dives which make recovery difficult. For the purpose of investigating these diving moments and finding means for their reduction, a 1/6 scale model of the airplane was tested in the 16-foot high-speed wind tunnel at Ames Aeronautical Laboratory. The test results indicate that up to a Mach number of at least 0.75, the limit of the tests, the dive-recovery difficulties can be alleviated and the longitudinal maneuverability improved by the substitution of a long symmetrical fuselage for the standard fuselage."

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The excellent performance of British ''red dot'' crystals is explained as due to the knife edge contact against a polished surface. High frequency rectification depends critically on the capacity of the rectifying boundary layer of the crystal. C. For high conversion efficiency, the product of this capacity and of the ''forward'' (bulk) resistance R{sub b} of the crystal must be small. For a knife edge, this product depends primarily on the breadth of the knife edge and very little upon its length. The contact can therefore have a rather large area which prevents burn-out. For a wavelength of 10 cm. the computations show that the breadth of the knife edge should be less than about 10{sup -3} cm. For a point contact the radius must be less than 1.5 x 10{sup -3} cm. and the resulting small area is conductive to burn-out. The effect of ''tapping'' is probably to reduce the area of contact.

Report presenting an investigation in the 19-foot pressure tunnel to determine the aerodynamic effects of several elevators with varying amounts of balance, of outboard split flaps, and of a droppable gas tank on a scale model of the F4U-1 airplane.

"The drags of two alternate turrets for a military airplane were investigated through a Mach number range of 0.22 to 0.70 at angles of attack of 3, 5, and 7 degrees in the 8-foot high-speed tunnel. Force and pressure measurements were made with the turrets mounted on a bomber model. The results show that a large spherical turret added about 10 percent to the fuselage drag" (p. 1).

"For the tunnel corrections of compressible flows those profiles are of interest for which at least the second approximation of the Janzen-Rayleigh method can be applied in closed form. One such case is presented by certain elliptical symmetrical cylinders located in the center of a tunnel with fixed walls and whose maximum velocity, incompressible, is twice the velocity of flow. In the numerical solution the maximum velocity at the profile and the tunnel wall as well as the entry of sonic velocity is computed" (p. 1).