Report published by the U.S. Bureau of Mines which is a compilation of accidents in quarries located in the United States with data regarding the number and kinds of accidents as well as information about the mining operations (e.g., number of men employed, kinds of quarries, amount of work performed, etc.).

Report compiled by the U.S. Bureau of Mines including statistics on fatal and non-fatal accidents in coal mines located in the United States as well as data regarding the various operations (e.g., number of miners employed and average production). The information is organized into tables for comparison and the text draws some overall conclusions in the summary.

Report issued by the Bureau of Mines over quarry accidents in the U.S. during 1937. The number, type, and location of the accidents are presented and discussed. This report includes tables.

"The pack method for determining compressive stress-strain graphs described in NACA Report No. 649 has been modified to extend it's application to thinner gages and stronger materials. The principal modifications consisted in the provision of additional support against instability cementing the specimens of the pack together with fused shellac and the provision of special clamps to hold the specimens together while the test is in progress. The shellac was found to increase the buckling load of the pack without any appreciable effect on the compressive stress-strain graph of the material" (p. 1).

From Introduction: "The principal purpose of the survey is to make public information not generally known concerning the gold deposits in the Black Hills. Operating mines, particularly the Homestake, are discussed only briefly."

Aerodynamic force tests of an NACA 23018 airfoil with a Gwinn flap having a chord 25 percent of the overall chord and of an NACA 23015 airfoil with a plain flap having a 25-percent chord were conducted to determine the relative merits of the Gwinn and the plain flaps. The tests indicated that, based on speed-range ratios, the plain flap was more effective than the Gwinn flap. At small flap deflections, the plain flap had lower drag coefficients at lift-coefficient values less than 0.70. For lift coefficients greater than 0.70, however, the Gwinn flap at all downward flap deflections had the lower drag coefficients.

Pressure-distribution tests of an NACA 0009 airfoil with an 80-percent-chord plain flap and three plain tabs, having chord of 10, 20, and 30 percent of the flap chord, were made. Section data suitable for application to the design of horizontal and vertical tail surfaces were obtained. Resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab are presented. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs. A comparison of some characteristic slopes for the 30-, the 50-, and the 80-percent-chord flaps, tested in the general investigation of plain flaps for control surfaces, is included. Section aerodynamic and load data have been made available for a wide range of flap and a tab chords to be used on an NACA 0009 airfoil or on other conventional sections.

From Summary: "Pressure-distribution tests of an NACA 0009 airfoil with a 30-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made. The purpose of these tests was to continue an investigation to supply structural and aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as diagrams of resultant pressures and of resultant-pressure increments for the airfoil with the flap and the 20-percent-chord tab. Increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs are also given. At all unstalled flap and tab deflections, the experimental distributions agree well with those calculated by an analytical method. The agreement is poor, however, then the stalled or the unstalled condition of the flap or tab deflected alone was changed to an unstalled or stalled condition by the simultaneous deflection of both the flap and the tab."

This report presents tables and charts for use in determining the characteristics of tapered wings. Theoretical factors are given from which the following characteristics of tapered wings may be found: the span lift distribution, the induced-angle-of attack distribution, the lift-curve slope, the angle of zero lift, the induced drag, the aerodynamic-center position, and the pitching moment about the aerodynamic center.

Report issued by the Bureau of Mines discussing the safety and ventilation hazards presented during the construction of the Wawona tunnel in Yosemite National Park. Safety precautions and procedures used during the construction are presented. This report includes tables, illustrations, and photographs.

From Summary: "As a preliminary step in an investigation of control-stick vibration in direct-control autogiros, the periodic variations in the moments transmitted through the control system of a YG-1B autogiro were recorded in flight. The results of the measurements are presented in the form of coefficients of Fourier series expressing the varying part of the lateral and the longitudinal moments acting between rotor and fuselage at the control trunnions. The most important component of the variation in stick force was found to have frequency of three times the rotor speed and an amplitude that rose from negligible values at tip-speed ratio below 0.20 to +/-5.2 pounds longitudinally and +/-3.2 pounds laterally at tip-speed ratios of 0.35. Variations in stick force at all other frequencies were small in comparison with those at three times the rotor speed."

The present report proposes the determination of the absolute magnitude of the total radiator drag and, in addition, of the different causes of the radiator drag.

Report presenting determinations of boundary-layer transition on the NACA 0012 and 23012 airfoils in the high-speed wind tunnel over a range of Reynolds numbers. For all of the lift coefficients that testing occurred at, transition occurred in the region of estimated laminar separation at low Reynolds numbers and approached the point of minimum static pressure as a forward limit at high Reynolds numbers.

Determinations of boundary-layer transition on the NACA 0012 and 2301 airfoils were made in the 8-foot high-speed wind tunnel over a range of Reynolds Numbers from 1,600,000 to 16,800,000. The results are of particular significance as compared with flight tests and tests in wind tunnels of appreciable turbulence because of the extremely low turbulence in the high-speed tunnel. A comparison of the results obtained on NACA 0012 airfoils of 2-foot and 5-foot chord at the same Reynolds Number permitted an evaluation of the effect of compressibility on transition.

In connection with the general problem of providing air flow to an aircraft power plant located within a fuselage, an investigation was conducted in the Langley 8-foot high-speed tunnel to determine the effect on external drag and pressure distribution of air inlet openings located at the nose of a streamline body. Air outlet openings located at the tail and at the 21-percent and 63-percent stations of the body were also investigated. Boundary layer transition measurements were made and correlated with the force and the pressure data. Individual openings were investigated with the aid of a blower and then practicable combinations of inlet and outlet openings were tested. Various modifications to the internal duct shape near the inlet opening and the aerodynamic effects of a simulated gun in the duct were also studied. The results of the tests suggested that outlet openings should be designed so that the static pressure of the internal flow at the outlet would be the same as the static pressure of the external flow in the vicinity of the opening.

Report presenting testing in the 8-foot high-speed wind tunnel to determine the effect on external drag and pressure distribution of air inlet openings on the stagnation point of a streamline body. The results showed that external drag of the body with suitably designed nose-inlet and tail-outlet openings over a wide range of rates of internal air flow was no higher than the drag of the streamline body. Specific results for the streamline body, nose-inlet openings, outlet openings, and inlet-outlet combinations are provided.

Report presenting tests conducted in the 8-foot high-speed wind tunnel of a scale model pursuit-type fuselage with practicable internal duct arrangement designed to meet all of the air requirements of a 1000-horsepower radial engine submerged at the maximum section. The results showed that the required internal flow can be obtained with negligible ducting losses provided that basic principles are observed in designing the air passages.

"Force tests were made of a 1/8-scale model of a twin-engine low-wing transport airplane in the NACA 8-foot high-speed wind tunnel to investigate compressibility and interference effects at speeds up to 450 miles per hour. In addition to tests of the standard arrangement of the model tests were made with several modifications designed to reduce the drag and to increase the critical speed. The results show serious increases in drag at critical speeds below 450 miles per hour due to the occurrence of compressibility burbles on the standard radial-engine cowlings, on sections of the wing as a result of wing-nacelle interference, and on the semi-retracted main landing wheels" (p. 1).

A set of propeller operating efficiency charts, based on a coefficient from which the propeller rotational speed has been eliminated, is presented. These charts were prepared with data obtained from tests of full-size metal propellers in the NACA propeller-research tunnel. Working charts for nine propeller-body combinations are presented, including results from tests of dual-rotating propellers. These charts are to be used in the calculation of the range and the endurance of airplanes equipped with constant-speed propellers in which, for given flight conditions, it is desired to determine the propeller revolution speed that gives the maximum ratio of the propulsive efficiency to the specific fuel consumption. The coefficient on which the charts are based may be written in the form of a thrust coefficient or a thrust-power coefficient. A method of using the charts is outlined and sample computations for a typical airplane are included.

"Test of 10-foot diameter, 4- and 6-blade single- and dual-rotating propellers were conducted in the 20-foot propeller-research tunnel. The propellers were mounted at the front end of a streamline body incorporating spinners to house the hub portions. The effect of a symmetrical wing mounted in the slipstream was investigated. The blade angles investigated ranged from 20 degrees to 65 degrees; the latter setting corresponds to airplane speeds of over 500 miles per hour" (p. 1).

"A preliminary investigation of a number of duct entrances of rectangular shape installed in the leading edge of a wing was conducted in the NACA 20-foot tunnel to determine the external drag, the available pressure, the critical Mach numbers, and the effect on the maximum lift. The results showed that the most satisfactory entrances, which had practically no effect on the wing characteristics, had their lips approximately in the vertical plane of the leading edge of the wing" (p. 1).

"Wind-tunnel tests of several propeller, cuff, and spinner combinations were conducted in the 20 foot propeller-research tunnel. Three propellers, which ranged in diameter from 8.4 to 11.25 feet, were tested at the front end of a streamline body incorporating spinners of two diameters. The tests covered a blade angle range from 20 deg to 65 deg. The effect of spinner diameter and propeller cuffs on the characteristics of one propeller was determined" (p. 1).

This paper presents an account of Italian high-speed engine designs. The tests were performed on the Fiat AS6 engine, and all components of that engine are discussed from cylinders to superchargers as well as the test set-up. The results of the bench tests are given along with the performance of the engines in various races.

An analysis of the cooling problem has been to show by what means the cooling of an air-cooled aircraft engine may be improved. Each means of improving cooling is analyzed on the basis of effectiveness in cooling with respect to power for cooling. The altitude problem is analyzed for both supercharged and unsupercharged engines. The case of ground cooling is also discussed. The heat-transfer process from the hot gases to the cylinder wall is discussed on the basis of the fundamentals of heat transfer and thermodynamics. Adiabatic air-temperature rise at a stagnation point in compressible flow is shown to depend only on the velocity of flow.