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  Partner: UNT Libraries Government Documents Department
 Collection: Technical Report Archive and Image Library
Abstracts of Current Decisions on Mines and Mining Reported from January to May 1918
Report issued by the Bureau of Mines over mining decisions made between January and May of 1918. Details of the decisions are presented and discussed.
Abstracts pertaining to seaplanes
About 400 references pertaining to the hydrodynamic design of seaplanes have been compiled, and the information is presented in the form of abstracts classified under six main headings.
Accelerated Laboratory Test for Determination of Slacking Characteristics of Coal
Report issued by the U.S. Bureau of Mines on laboratory testing developed to measure the slacking of coals. Testing methods and results are presented. This report includes tables and graphs.
Acceleration characteristics of a turbojet engine with variable-position inlet guide vanes
No Description
Acceleration Characteristics of R-3350 Engine Equipped with NACA Injection Impeller
Qualitative investigations have shown that use of the NACA injection impeller with the R-3350 engine increases the inertia of the fuel-injection system and, when the standard fuel-metering system is used, this increase in inertia results in poor engine acceleration characteristics. This investigation was therefore undertaken to determine whether satisfactory acceleration characteristics of the engine equipped with the injection impeller could be obtained by simple modifications to the fuel-monitoring system. The engine was operated with two types of carburetor; namely, a hydraulic-metering carburetor incorporating a vacuum-operated accelerating pump and a direct-metering carburetor having a throttle-actuated accelerating pump. The vacuum-operated accelerating pump of the hydraulic-metering carburetor was modified to produce satisfactory accelerations by supplementing the standard air chamber with an additional 75-cubic spring. The throttle-actuated accelerating pump of the direct-metering carburetor was modified to produce satisfactory accelerations by replacing the standard 0.028-inch-diameter bleed in the load-compensator balance line with a smaller bleed of 0.0225-inch diameter. The results of this investigation indicated that both carburetors can be easily modified to produce satisfactory acceleration characteristics of the engine and no definite choice between the types of carburetor and accelerating pump can be made. Use of the direct-metering carburetor, however, probably resulted in better fuel distribution to the cylinders during the acceleration period and reduced the backfire hazard because all the fuel is introduced through the injection impeller.
Acceleration Due to Gravity at the National Bureau of Standards
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Acceleration Measurements During Landing in Rough Water of a 1/7-Scale Dynamic Model of Grumman XJR2F-1 Amphibian - Langley Tank Model 212, TED No. NACA 2378
Tests of a 1/7 size model of the Grumman XJR2F-1 amphibian were made in Langley tank no.1 to examine the landing behavior in rough water and to measure the normal and angular accelerations experienced by the model during these landings. All landings were made normal to the direction of wave advance, a condition assumed to produce the greatest accelerations. Wave heights of 4.4 and 8.0 inches (2.5 and 4.7 ft, full size) were used in the tests and the wave lengths were varied between 10 and 50 feet (70 and 350 ft, full size). Maximum normal accelerations of about 6.5g were obtained in 4.4 inch waves and 8.5g were obtained in 8.0 inch waves. A maximum angular acceleration corresponding to 16 radians per second per second, full size, was obtained in the higher waves. The data indicate that the airplane will experience its greatest accelerations when landing in waves of about 20 feet (140 ft, full size) in length.
Acceleration Measurements During Landings of a 1/5.5-Size Dynamic Model of the Columbia XJL-1 Amphibian in Smooth Water and in Waves: Langley Tank Model 208M, TED No. NACA 2336
A 1/5.5-size powered dynamic model of the Columbia XJL-1 amphibian was landed in Langley tank no. 1 in smooth water and in oncoming waves of heights from 2.1 feet to 6.4 feet (full-size) and lengths from 50 feet to 264 feet (full-size). The motions and the vertical accelerations of the model were continuously recorded. The greatest vertical acceleration measured during the smooth-water landings was 3.1g. During landings in rough water the greatest vertical acceleration measured was 15.4g, for a landing in 6.4-foot by 165-foot waves. The impact accelerations increased with increase in wave height and, in general, decreased with increase in wave length. During the landings in waves the model bounced into the air at stalled attitudes at speeds below flying speed. The model trimmed up to the mechanical trim stop (20 deg) during landings in waves of heights greater than 2.0 feet. Solid water came over the bow and damaged the propeller during one landing in 6.4-foot waves. The vertical acceleration coefficients at first impact from the tank tests of a 1/5.5-size model were in fair agreement with data obtained at the Langley impact basin during tests of a 1/2-size model of the hull.
Acceleration of high-pressure-ratio single-spool turbojet engine as determined from component performance characteristics : effect of compressor interstage air bleed
No Description
Acceleration of high-pressure-ratio single-spool turbojet engine as determined from component performance characteristics I : effect of air bleed at compressor outlet
An analytical investigation was made to determine from component performance characteristics the effect of air bleed at the compressor outlet on the acceleration characteristics of a typical high-pressure-ratio single-spool turbojet engine. Consideration of several operating lines on the compressor performance map with two turbine-inlet temperatures showed that for a minimum acceleration time the turbine-inlet temperature should be the maximum allowable, and the operating line on the compressor map should be as close to the surge region as possible throughout the speed range. Operation along such a line would require a continuously varying bleed area. A relatively simple two-step area bleed gives only a small increase in acceleration time over a corresponding variable-area bleed. For the modes of operation considered, over 84 percent of the total acceleration time was required to accelerate through the low-speed range ; therefore, better low-speed compressor performance (higher pressure ratios and efficiencies) would give a significant reduction in acceleration time.
Acceleration of high-pressure-ratio single-spool turbojet engine as determined from component performance characteristics III : effect of turbine stator adjustment
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An acceleration schedule control for accelerating a turbojet engine and its use with a speed control
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An acceleration schedule control for accelerating a turbojet engine and its use with a speed control
Accelerating-limiting controls for turbojet engines.
Acceleration, stress, and deflection measurements on the XB-15 bomber in gusty air
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Accelerations and bottom pressures measured on a B-24D airplane in a ditching test
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Accelerations and passenger harness loads measured in full-scale light-airplane crashes
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Accelerations in fighter-airplane crashes
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Accelerations in flight
This report deals with the accelerations obtained in flight on various airplanes at Langley Field for the purpose of obtaining the magnitude of the load factors in flight and to procure information on the behavior of an airplane in various maneuvers. The instrument used in these tests was a recording accelerometer of a new type designed by the technical staff of the National Advisory Committee for Aeronautics. The instrument consists of a flat steel spring supported rigidly at one end so that the free end may be deflected by its own weight from its neutral position by any acceleration acting at right angles to the plane of the spring. This deflection is measured by a very light tilting mirror caused to rotate by the deflection of the spring, which reflected the beam of light onto a moving film. The motion of the spring is damped by a thin aluminum vane which rotates with the spring between the poles of an electric magnet. Records were taken on landings and takeoffs, in loops, spins, spirals, and rolls.
Accelerations in flight
This work on accelerometry was done at McCook Field for the purpose of continuing the work done by other investigators and obtaining the accelerations which occur when a high-speed pursuit airplane is subjected to the more common maneuvers. The accelerations obtained in suddenly pulling out of a dive with well-balanced elevators are shown to be within 3 or 4 per cent of the theoretically possible accelerations. The maximum acceleration which a pilot can withstand depends upon the length of time the acceleration is continued. It is shown that he experiences no difficulty under the instantaneous accelerations as high as 7.8 G., but when under accelerations in excess of 4.5 G., continued for several seconds, he quickly loses his faculties.
Accelerations in Landing with a Tricycle-Type Landing Gear
In connection with the application of stable tricycle-type landing gears to transport airplanes, the question arises as to whether certain passengers may not experience relatively great accelerations in an emergency landing. Since the main landing wheels are behind the center of gravity in this type of gear, a hard-braked landing will cause immediate nosing down of the airplane and, when this motion is stopped due to the front wheel striking the ground, there will be some tendency for the rearmost passengers to be thrown out of their seats, The provided rough calculations are designed to show the magnitudes of the various reactions experienced in a severe landing under these circumstances.
Accelerations in transport-airplane crashes
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Accelerations measured at center of gravity and along span of the wing of a B-24D airplane in landing impacts
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Accelerometer design
In connection with the development of an accelerometer for measuring the loads on airplanes in free flight a study of the theory of such instruments has been made, and the results of this study are summarized in this report. A portion of the analysis deals particularly with the sources of error and with the limitations placed on the location of the instrument in the airplane. The discussion of the dynamics of the accelerometer includes a study of its theoretical motions and of the way in which they are affected by the natural period of vibration and by the damping, together with a report of some experiments on the effect of forced vibrations on the record.
Accepted Limit Values of Air Pollutants
Report issued by the U.S. Bureau of Mines discussing, as stated in the introduction, the "accepted maximum permissible concentrations of air pollutants from the standpoints of health, damage to vegetation, damage to property, and requirements of industrial processes" (p. 1). This report includes tables.
Accident Experience: Iron-Ore Mines, Lake Superior District, 1940-43
Report issued by the U.S. Bureau of Mines discussing the iron-ore mining accident experience in the Lake Superior District. Frequency and severity rates of accidents between 1940 and 1943 are presented. This report includes tables.
Accident-Severity Rates For Certain Metal Mines
Report issued by the U.S. Bureau of Mines on the severity of accidents in the metal-mine industry. 34 metal-mines documented the number and severity of all accidents over the course if one calendar year. This report includes tables.
Accidents from explosives at metal and nonmetallic mines
Circular produced by the U.S. Bureau of Mines to promote safety through a series of reports on accident prevention in mines. According the the scope statement, "This is the fourth section of the revised series of circulars that cover various phases of accident prevention in metal and nonmetallic mines; it give information on accidents and injuries from storing, handling, and using explosive in metal and nonmetallic mines and discusses the precautions by which they can be prevented" (p. 2).
Accounting System and Office-Management Procedure for Medium-Size Metal Mines
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Accuracy of airspeed measurements and flight calibration procedures
The sources of error that may enter into the measurement of airspeed by pitot-static methods are reviewed in detail together with methods of flight calibration of airspeed installations. Special attention is given to the problem of accurate measurements of airspeed under conditions of high speed and maneuverability required of military airplanes. (author).
Accuracy of approximate methods for predicting pressures on pointed nonlifting bodies of revolution in supersonic flow
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The accuracy of the substitute-stringer approach for determining the bending frequencies of multistringer box beams
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An accurate and rapid method for the design of supersonic nozzles
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Accurate calculation of multispar cantilever and semicantilever wings with parallel webs under direct and indirect loading
In the present report the computation is actually carried through for the case of parallel spars of equal resistance in bending without direct loading, including plotting of the influence lines; for other cases the method of calculation is explained. The development of large size airplanes can be speeded up by accurate methods of calculation such as this.
An accurate method of measuring the moments of inertia of airplanes
This note contains a description of an improved apparatus and procedure used by the NACA for determining the moments of inertia of airplanes. The method used, based on the pendulum theory, is similar to that previously used, but a recent investigation of its accuracy has resulted in the improvements described herein. The error, when using the new apparatus and procedure, has been found to be of the order of 1 per cent.
Achievement of continuous wall curvature in design of two-dimensional symmetrical supersonic nozzles
No Description
Acid-Base Behavior in Aprotic Organica Solvents
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Acid-Mine-Drainage Problems: Anthracite Region of Pennsylvania
Report from the U.S. Bureau of Mines discussing the anthracite region of Pennsylvania and the efforts to prevent coal-mine drainage into nearby streams. According to the introduction, "The purpose of this report is not to develop a practicable or feasible method or process of treating acid mine water but rather to present available factual and deduced data that may be useful in showing pH range over which the treatment is to take place and the sludge products most likely to be handled" (p. 2).
Acid Processes for the Extraction of Alumina
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Acoustic analysis of ram-jet buzz
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Acoustic radiation from two-dimensional rectangular cutouts in aerodynamic surfaces
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Acoustic, thrust, and drag characteristics of several full-scale noise suppressors for turbojet engines
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Acoustical treatment for the NACA 8- by 6-foot supersonic propulsion wind tunnel
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Acoustics of a nonhomogeneous moving medium.
Theoretical basis of the acoustics of a moving nonhomogeneous medium is considered in this report. Experiments that illustrate or confirm some of the theoretical explanation or derivation of these acoustics are also included.
Activation of hydrocarbons and the octane number
This report presents an examination of the history of research on engine knocking and the various types of fuels used in the investigations of this phenomenon. According to this report, the spontaneous ignition of hydrocarbons doped with oxygen follows the logarithmic law within a certain temperature range, but not above 920 degrees K. Having extended the scope of investigations to prove hydrocarbons, the curves of the mixtures burned by air should then be established by progressive replacement of pure iso-octane with heptane. Pentane was also examined in this report.
An active particle diffusion theory of flame quenching for laminar flames / Dorothy M. Simon and Frank E. Belles
An equation for quenching distance based on the destruction of chain carriers by the surface is derived. The equation expresses the quenching distance in terms of the diffusion coefficients and partial pressures of the chain carriers and gas phase molecules, the efficiency of the surface as a chain breaker, the total pressure of the mixture, and a constant which depends on the geometry of the quenching surface. Quenching distances measured by flashback for propane-air flames are shown to be consistent with the mechanism. The derived equation is used with the lean inflammability limit and a rate constant calculated from burning velocity data to estimate quenching distances for propane-air (hydrocarbon lean) flames satisfactorily.
Adaptation of a Cascade Impactor to Flight Measurement of Droplet Size in Clouds
A cascade impactor, an instrument for obtaining: the size distribution of droplets borne in a low-velocity air stream, was adapted for flight cloud droplet-size studies. The air containing the droplets was slowed down from flight speed by a diffuser to the inlet-air velocity of the impactor. The droplets that enter the impactor impinge on four slides coated with magnesium oxide. Each slide catches a different size range. The relation between the size of droplet impressions and the droplet size was evaluated so that the droplet-size distributions may be found from these slides. The magnesium oxide coating provides a permanent record. of the droplet impression that is not affected by droplet evaporation after the. droplets have impinged.
Adaptation of aeronautical engines to high altitude flying
Issues and techniques relative to the adaptation of aircraft engines to high altitude flight are discussed. Covered here are the limits of engine output, modifications and characteristics of high altitude engines, the influence of air density on the proportions of fuel mixtures, methods of varying the proportions of fuel mixtures, the automatic prevention of fuel waste, and the design and application of air pressure regulators to high altitude flying. Summary: 1. Limits of engine output. 2. High altitude engines. 3. Influence of air density on proportions of mixture. 4. Methods of varying proportions of mixture. 5. Automatic prevention of fuel waste. 6. Design and application of air pressure regulators to high altitude flying.
Adaptation of Combustion Principles to Aircraft Propulsion, Volume 2, Combustion in Air-Breathing Jet Engines
This volume continues the NACA study of combustion principles for aircraft propulsion. The various aspects of combustion pertinent to jet engines are organized and interpreted with quite extensive information, particularly for basic or fundamental. subject matter. The report concerns only air-breathing engines and hydrocarbon fuels, and not rocket engines and high-energy fuels. Since the references have been selected to illustrate important points, the bibliographies, while thorough, are not complete. This volumes describes the observed performance and design problems of engine combustors of the principal types. These include combustor-inlet conditions; starting, acceleration, combustion limits, combustion efficiency, coke deposits, and smoke formation in turbojets; ram-jet performance; and afterburner performance and design.
Adaptation of Combustion Principles to Aircraft Propulsion, Volume I, Basic Considerations in the Combustion of Hydrocarbon Fuels with Air
The report summarizes source material on combustion for flight-propulsion engineers. First, several chapters review fundamental processes such as fuel-air mixture preparation, gas flow and mixing, flammability and ignition, flame propagation in both homogenous and heterogenous media, flame stabilization, combustion oscillations, and smoke and carbon formation. The practical significance and the relation of these processes to theory are presented. A second series of chapters describes the observed performance and design problems of engine combustors of the principal types. An attempt is made to interpret performance in terms of the fundamental processes and theories previously reviewed. Third, the design of high-speed combustion systems is discussed. Combustor design principles that can be established from basic considerations and from experience with actual combustors are described. Finally, future requirements for aircraft engine combustion systems are examined.
Adaptor for measuring principal strains with Tuckerman strain gage
An adapter is described which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.