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Technical Paper

Reducing Horsepower and Noise of Automotive Cooling-Fans

1931-01-01
310014
STATING the automotive cooling-fan problem as being constituted of the delivery of more air, decrease of fan horsepower, reduction of fan noise so that it is comparable with or less than other powerplant noises and the installation of the fan in a restricted space, the author describes the testing apparatus and method used in analyzing the subject. Fan speeds and the most effective number of blades are then considered, followed by analyses of fan diameter and pitch and curvature of fan blades. The manner in which air is discharged from the fan and the adaptation of a fan to an automobile are also discussed. Following statements concerning the desirable number of fan blades and blade spacing, noise characteristics of fans are analyzed in detail as a preface to the author's consideration of means of reducing fan noise, and a summary listing the conclusions reached as a result of the study is appended.
Technical Paper

Time Lag in Detonation Determinations

1931-01-01
310028
IN matching one fuel against another directly with a double-float carbureter, the knock sometimes either disappears or increases in intensity when the change from one fuel to the other is made. Results of a study of this subject, which was made recently, are presented in the paper. From the tests the conclusion is drawn that means should be provided to dry out the mixture between the carbureter and the cylinder-block of the engine used for antiknock measurement. Before a satisfactory answer to the problem can be reached, however, several other points require further investigation.
Technical Paper

Bouncing-Pin versus Throttle-Audibility - Annual Meeting Paper

1931-01-01
310027
EXPERIMENTS to determine if any difference in fuel matching by bouncing-pin or throttle-audibility on the same engine are described, also tests to determine if the Cooperative-Fuel-Research and Series-30 Ethyl Gasoline Corp. engines gave similar results for either method. To check these tests another study to find the relative precision of these two methods of knock testing was made. From these tests the conclusion is drawn that, with few exceptions, little difference could be detected in matching fuels on either the Ethyl Gasoline Corp. Series-30 or the Cooperative Fuel-Research engine.
Technical Paper

Effect of Sound Intensity on Knock Ratings

1931-01-01
310026
MEASURING knock-sound intensity by a microphone and vacuum-tube amplifying set is described in this paper. Widely varying fuels are compared with mixtures of normal heptane and iso-octane at knock intensities ranging from incipient knock to a knock severe enough to cause preignition. The conclusion is drawn that, for tests on the L-head Cooperative Fuel-Research knock-testing engine, the intensity of knock at which tests are made does not affect the knock ratings if a fuel-matching method is used.
Technical Paper

Influence of Carbureter Setting and Spark Timing on Knock Ratings - Annual Meeting Paper

1931-01-01
310025
THAT the antiknock quality of a motor fuel is best determined by comparison with a standard or reference fuel is generally agreed. The results of the investigation described in this paper show how this comparison may be affected either by the carbureter adjustment or by the spark timing or by both. Therefore, in establishing a standard method of comparing one fuel with another, some definite specification covering each of these two engine-variables must be drawn up. This specification should correspond reasonably well with conventional conditions of engine operation and at the same time with convenient laboratory technique. From the results of this study these conditions would appear to be fulfilled best by using the carbureter setting for maximum knock and the spark timing for maximum power.
Technical Paper

Effect of Oil Consumption and Temperature on Octane-Number Ratings

1931-01-01
310024
STATING that variation in knock-testing results with a relatively high oil-consumption is partly due to the oil itself, the series of tests conducted at the laboratory of the Standard Oil Development Co. is described. This is supplemented by tables giving the average results obtained in several tests in which the operating conditions were very carefully controlled. Conclusions drawn by the author are that the error due to different rates of oil consumption and variation of oil temperature may be as great as one octane number and is not affected by the kind of oil used. Recommendations that the oil consumption be kept at the minimum for safety and good operation and that the oil temperature be kept constant at as low a value as is consistent with good lubrication are made.
Technical Paper

Jacket and Cylinder-Head Temperature Effects upon Relative Knock-Ratings

1931-01-01
310023
DATA that were obtained while investigating some of the variables affecting the relative antiknock values of certain fuels are presented to show that if one condition of knock testing is varied, at least one other condition must also be varied. Increasing the jacket temperature necessitates increasing the knock intensity, decreasing the throttle opening or the compression ratio or retarding the spark. Two sets of tests were run. One consisted in adding tetraethyl lead or crude benzene to one of the six test fuels to make it equal in knock intensity to each of the other five. In the other series the quantities of tetraethyl lead that must be added to a straight-run Mid-Continent gasoline to give knock ratings equal to different percentages of chemically pure benzene in the same fuel were determined. The results of both series, which led to somewhat opposing conclusions, are presented in tables and charts, and a possible explanation of this conflict is given.
Technical Paper

Effect of Humidity and Air Temperature on Octane Numbers of Secondary Detonation-Standards

1931-01-01
310022
AFTER stating briefly the requirements that reference fuels used in determining the detonation values of test fuels should meet, the tests conducted by the Bureau of Standards to ascertain the effect that atmospheric conditions have upon the relations between the primary scale and each of a number of secondary detonation-standards are described. All tests were made with a Cooperative Fuel-Research engine having a 6:1 compression-ratio L-head. Varying the throttle opening gave the desired intensity of detonation, which was estimated by the bouncing-pin apparatus. Air-conditioning apparatus, used in previous tests, controlled the air temperature and humidity.
Technical Paper

A Study of Airplane and Instrument- Board Vibration

1931-01-01
310036
AIRPLANE vibration produces many undesirable conditions during flight, such as fatigue of structural members, a bad effect on the nervous systems of the occupants and the like. Excessive vibration leads to premature deterioration or to erroneous indications of instruments. Vibrations can be analyzed from a mathematical viewpoint with gratifying results, but such analysis is sometimes difficult and often is applicable only to selected conditions. A serious mathematical analysis was carried out in the investigation of resonance conditions between engine and engine mount. Then the problem was approached from a rather empirical viewpoint to give vibration relations, not, as heretofore, to bodily sensation, but to such terms as amplitude, frequency, the relation between the two, form and the like.
Technical Paper

Weight Saving by Structural Efficiency

1931-01-01
310034
METHODS employed by the author to reduce the weight of the structural frame without sacrificing strength are described in the paper. To obtain this result the best available cross-section must be selected and the members arranged to transmit the load directly to the final supports which should lie approximately in a plane that is parallel to the load vector; also where a bending moment is caused by the loading, the support attachment should produce a moment of the same amount and of opposite sign. Avoiding secondary bending and utilizing the advantages of full continuity over supports can be secured by a simple arrangement of the frame members. Substitution of power tools for hand tools will effect a reduction in assembly costs. Sections suitable for power assembly include closed hollow-sections, which have a high structural efficiency, as well as angles, channels, I-beams and similar shapes.
Technical Paper

Increasing the Thrust Horsepower from Radial Air-Cooled Engines

1931-01-01
310037
MANUFACTURERS of radial air-cooled engines have centered their attention upon low specific weight for their product. This is accomplished by compact design, using the best of materials and the highest grade of workmanship and finish, with the production of the maximum possible horsepower per cubic inch of engine displacement. High output can be accomplished by a combination of high rotative speed and high brake mean effective pressure with low friction losses. Many considerations of design and operation must be correctly proportioned to approach the ultimate in horsepower. Important advances have been made in improving engine output by cooling air-cooled cylinders with well designed fins supplied with air from directing baffles, thus increasing the brake mean effective pressure which can be produced on a given fuel without detonation.
Technical Paper

Applied Load Factors in Bumpy Air

1931-01-01
310035
THE PAPER supplements the paper on Weight Saving by Structural Efficiency2, prepared by Charles Ward Hall. Mr. Hall's paper was confined to a discussion of the design; Mr. Rhode's paper treats the loading conditions, because their sound establishment is the foundation of a safe and efficient structure. The basic character of the loading conditions is sufficient cause to justify extensive study of their underlying principles, since, in addition, structural failures are occurring which can be traced definitely to inadequate strength requirements and the study of the loading conditions becomes a problem of immediate practical importance, the author states. Mr. Rhode's analysis is confined to the loading conditions on the wings of airplanes in the non-acrobatic category with particular reference to the total loads acting.
Technical Paper

Observations on the Testing of Lubricants

1931-01-01
310032
INABILITY of the roller-bearing company with which the author of this paper is connected to obtain from oil manufacturers or others the information it desired regarding the properties of lubricants for transmissions and rear axles caused the company to undertake to secure the information at first hand itself. It began testing lubricants for their abrasive qualities and their load-carrying capacities. The investigators soon realized that the usual physical tests do not prove the effects of lubricants on gears. Therefore two machines were built, one to give the scuffing properties and the other to give the abrasive properties, the latter being the more important as regards antifriction bearings.
Technical Paper

The Field for Synthetic Lubricating Oils

1931-01-01
310033
ONE method employed in a fundamental investigation of the composition of lubricating oils as it affects the viscosity characteristics has involved the synthesis of viscous oils by polymerizing a wide range of olefins with a condensing agent, such as aluminum chloride. Many thousand gallons of synthetic lubricating oils have been made within the last two or three years from olefins produced by cracking paraffin waxes. Details of the process have been published previously and hence are not included. The present paper deals with the characteristics of two such oils that have been synthesized in commercial quantities. The raw materials and the process of manufacture make these more expensive than ordinary motor oils, but their temperature-viscosity characteristics make them desirable for use in transmission and steering mechanisms and in hydraulic shock-absorbers, as they are less susceptible than the usual oil to viscosity changes with changes of temperature.
Technical Paper

A Further Study of the Air-Jet Method for Determining Gum in Gasolines

1931-01-01
310031
IN a previous paper covering a comparison of several methods for determining gum in gasolines, the conclusion was reached that the air-jet method gave the lowest and most reproducible results. Since gum deposition in the engine occurs in the presence of air, a more extended study of that method was undertaken. By evaporation of different volumes of gasoline and of various blends with a gum-free gasoline in each case, the concentration of gum and of gum-forming constituents was found to be one of the most important factors in determining the gum content. The temperature of the gasoline and the oxygen concentration in the atmosphere surrounding it during evaporation appeared to have little effect on the results. Further work on methods for determining the gum content is contemplated.
Technical Paper

A Comparison of Methods for Determining Gum Contents of Gasolines1

1931-01-01
310030
WIDESPREAD adoption of crude-oil cracking processes to provide an adequate supply of gasoline of high antiknock value has introduced the gum problem. The solution of this depends upon the development of a satisfactory method for determining the true gum-content of a fuel at the time of test and for predicting the content of a gasoline stored for a given time under specified conditions, and upon the correlation of data obtained by these methods with the results of engine tests. Several methods proposed and used for determining the gum content of gasolines are described and data obtained by means of them are compared.
Technical Paper

Magnesium Industry's Lightest Structural Metal

1931-01-01
310044
AFTER reviewing briefly the history of the aluminum and magnesium industries, the author describes foundry practice in the production of magnesium and magnesium-alloy castings, their heat-treatment and the effect of various fabrication processes on the microstructure and physical properties. The general classes of commercial magnesium-base alloys now in use in this Country are discussed at some length with particular reference to the combination of extreme lightness with good physical and mechanical properties that is obtained. Applications of magnesium alloys in the aircraft and automobile industries are outlined in a section of the paper. Many of these are illustrated. In conclusion the author states that the importance of magnesium as a structural metal is now being recognized, especially as the factors that have retarded its development and restricted its use are overcome.
Technical Paper

The Turbo Supercharger

1931-01-01
310042
An outline history of the development of the turbo supercharger is presented, showing the progress of the supercharger and the related airplane parts. A brief history is given of the fuel systems, cooling systems, exhaust manifolds and nozzle boxes, turbine buckets, propellers, ignition systems, carbureters, intercoolers and bearings and lubrication, and a description of the developments that have recently taken place in these fields. A study is made of the power required by the compressor and power delivered by the turbine on the basis of certain assumptions that may be at variance with the facts. Nevertheless, the study shows trends and the general order of efficiencies. From this paper, the conclusion is reached that the turbo supercharger is a serviceable piece of equipment for maintaining sea-level pressure at the carbureters to altitudes.
Technical Paper

Controlling Factors in Machine-Tool Obsolescence

1931-01-01
310045
IN THIS PAPER, obsolescence is considered as concerning the economic value of a machine regardless of its physical condition or age. Improved machinery may make a tool obsolete while it is relatively new. Distinctions are drawn between obsolescence, depreciation and amortization, and a list of controlling and contributing factors in obsolescence is given. Objection is made to the lumping of obsolescence and depreciation in a single charge, which apparently is not great enough to cover obsolescence with the present accelerated rate of machine-tool progress. Three examples are given of formulas or methods of determining the economic advisability of purchasing new equipment, and their use is illustrated by being applied to a set of assumed conditions. Yield, risk and liquidity are said to control investments in new equipment, the same as any other investments.
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