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1931-01-01
Technical Paper
310049
H. E. Fromm
THE SUCCESS attained by marine engines as built by the manufacturer of motor-vehicle engines clearly proves that such engines are entirely suitable for marine service provided rugged automobile, truck or motorcoach engines are used as a basis. However, this involves the necessity of applying the principles of marine design and practices. The author describes and illustrates such an engine developed and built by a leading motor-car-engine manufacturing company. This makes possible the use of cylinder blocks, crankshafts, pistons, valves, tappets and many other minor parts used in the motor-vehicle engines. The outstanding advantage is the use of modern methods of production, equipment, quantity purchasing and the financial resources of the automobile industry.
1931-01-01
Technical Paper
310037
Philip B. Taylor
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.
1931-01-01
Technical Paper
310038
Roland Chilton
THE TWO MAJOR REQUIREMENTS for good cooling of an air-cooled cylinder-head are (a) adequate conductivity from the zones of maximum heat-flow, that is, the spark-plug bosses and the exhaust-valve seats, elbows and guides, to a sufficient area of finning, and (b) the maintenance of a high-velocity air-flow over the entire length and depth of all fins. Solution of the problem of (b) depends upon many items in the engine installation outside of the cylinder-head. A limit to possible power output of the cylinder is set by detonation, which, with a given fuel, depends upon the cylinder-head temperatures. As these temperatures are the basic index of operating conditions of air-cooled engines, the author states that a head thermocouple instrument should be standard equipment on every airplane, and pilots should be trained to respect head temperatures as much as they now respect oil pressures and temperatures.
1931-01-01
Technical Paper
310039
E. S. Taylor
DETERMINATION of the approximate distribution of the loads on the main bearings of radial aircraft-engines, so that the bearings can be correctly proportioned and the stresses in the crankshaft can be more accurately calculated, is the purpose of this investigation. Six radial-engine crankshafts were tested statically to determine the main-bearing loads. The results of these tests are presented in the form of tables and diagrams. General conclusions are drawn from these results. A short method of calculating the crankpin-bearing load, which gives results in a convenient form, is included.
1931-01-01
Technical Paper
310040
Ford L. Prescott, Roy B. Poole
FOR the rapid calculation of bearing loads in aircraft engines the authors have developed an analytical method that is described for the first time in the paper. This was derived from the long tedious graphical method that was formerly used and its accuracy is asserted to be sufficient for all purposes of engine design. Results of an analysis of the bearing loads in the Curtiss V-1570 Conqueror engine which were obtained by the graphical method are first presented in considerable detail. The Wright R-1750 Cyclone is next analyzed, the method that was employed not being as precise as that used for the other engine. An application of the analytical method using empirical constants derived from a graphical analysis of various engines is also presented. Numerous illustrations and tables supplement the text.
1931-01-01
Technical Paper
310041
Oscar W. Schey
CLASSIFYING the superchargers used for present aircraft and automobile service as Roots, centrifugal and vane types, the author states that the vane type for this service is a more recent development than the other two and describes each type. He states further that the ideal type should satisfy many requirements closely related with those of a well-designed engine-such as being light, compact and reliable-and that the practice of supercharging has increased considerably during the last few years. The comparative performance of superchargers is treated at some length, and engine-performance data are presented. The power developed by an engine equipped with geared-centrifugal, turbo-centrifugal and Roots superchargers is illustrated by curves, control methods are compared, net engine-power is computed, and flight-test data on comparative performance are analyzed.
1931-01-01
Technical Paper
310042
A. L. Berger, Opie Chenoweth
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.
1931-01-01
Technical Paper
310013
Delmar G. Roos, William S. James
ONE-DIRECTION clutches have been applied to motor-cars to prevent the engine from being driven by the car when coasting and to facilitate gear-shifting. A number of representative designs are described in detail and in relation to their location in the transmission line. Following this is a detailed description of the construction and operation of the free-wheel device as applied to the Studebaker transmission, in which it takes the form of a single overrunning-clutch placed between the clutch gear and the splined shaft of the transmission in such a way that it serves to clutch either direct drive or second gear in either free-wheeling or positive engagement. Twelve rollers of graduated sizes are arranged in three groups in contact with three cam surfaces in the clutch. Sizes of rollers and dimensions of the cam surfaces are given. Tests were made for durability of the device, for savings in fuel and oil, and for any increase in demands on the brakes and generator.
1931-01-01
Technical Paper
310014
A. D. Gardner
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.
1931-01-01
Technical Paper
310011
E. F. Ruehl
MORE attention must be paid to light-weight design and to flexible combustion control if the Diesel engine is to become a serious competitor of the gasoline engine. The relative merits of existing types of combustion-chamber and injection systems used in present commercial four-cycle engines are discussed, and it is shown that the single-turbulence-chamber type offers the most promising means to high mean effective pressures at low fuel consumption. Stock high-pressure fuel-pumps and injection-valves, produced in volume by specialists, will have a great influence on the production of high-speed Diesel engines. The interrelation of combustion and injection processes in controlled-turbulence combustion-chambers is explained, and design details and test results are given of the practical application of single-chamber principles and of a stock injection system to flexible combustion control in a recently developed high-speed four-cycle engine.
1931-01-01
Technical Paper
310012
H. M. Crane
1931-01-01
Technical Paper
310017
Oscar C. Bridgeman, Hobart S. White
PREVIOUS work on vapor lock at the Bureau of Standards under the auspices of the Cooperative Fuel Research Steering Committee has resulted in considerable information regarding the relation between the properties of gasolines and vapor lock and between fuel-line design and vapor lock. Satisfactory means have been developed for predicting the conditions under which vapor lock would occur with a given fuel, but no extensive information has been available on the gasoline temperatures existing in the fuel feed lines of automotive equipment. This has made it very difficult for the refiner to supply satisfactory fuels for current automotive equipment. The present report includes temperature data obtained at several points in the fuel feed systems of 27 automobiles and 8 buses under various operating conditions.
1931-01-01
Technical Paper
310018
Oscar C. Bridgeman, Hobart S. White
THE PRESENT PAPER covers the results obtained in a second survey of fuel-line temperatures. Road tests were made on a large number of 1931 cars operated under various specified conditions, and fuel temperatures were measured in each case at several points in the fuel-feed system. On the average, no material improvement over the 1930 models was found. Individual models had been improved considerably, while others had become worse. This unchanged situation may be due, in part, to the fact that the results of the 1930 survey were not available in time so that full advantage could be taken of the conclusions in designing the 1931 models. Reasonable protection for most of the 1931 cars as regards fuel cannot be obtained in hot weather if they are run on gasolines having a Reid vapor pressure higher than 7 lb. per sq. in.
1931-01-01
Technical Paper
310005
C. F. Taylor, E. S. Taylor, G. L. Williams
THIS investigation was carried out in the aeronautical-engine laboratory at the Massachusetts Institute of Technology to determine the practical value of the use of a fuel-injection system in place of a carbureter on an Otto-cycle engine using spark ignition. Gasoline was used for most of the investigation, but comparative tests were also made using fuel oil. The equipment used was a single-cylinder laboratory-test engine and such other apparatus as was necessary for a complete performance test. A Diesel-engine injection-pump was used. A Diesel-type injection valve was used for injection into the inlet manifold, and a valve of special design, giving fine spray and little penetration, was used for the tests in which the injection was into the cylinder.
1931-01-01
Technical Paper
310006
Erich Sandner, J. Barraja-Frauenfelder
EARLY troubles experienced with torsional vibration in the shafting of marine and Diesel engines are mentioned, following which the various types of torsional-vibration damper are listed. Comments on the different ones are presented with particular reference to a damper with hydraulic coupling for a 3000-hp. 10-cylinder Diesel engine. The operation of this damper is described at some length, the text being supplemented by illustrations. Results of tests with this device are presented graphically, and the conclusion is drawn that the damping flywheel with hydrostatic coupling permits (a) damping of vibration of shafting even when running in the most dangerous speed-ranges of the largest engines and (b) running at all speeds without regard to vibration and without resorting to hand operation of the damping device.
1931-01-01
Technical Paper
310004
E. S. Marks, C. T. Doman
FEATURES of the design of the various cylinders built by the Franklin organization in its development program leading up to the present design are discussed in this paper. The relation of waste heat to cooling-fin areas and cooling-blast velocities is shown and discussed for cylinders up to 3½-in. bore. Characteristics of the cooling system, including fan, fan housing and air housings, are discussed at length, and the authors contend that no more power, if as much, will be absorbed in the cooling system as in that of the indirect air-cooled engine. Results of tests showing the ability of the engine to cool under the severest conditions of load and temperature are given. Since the quietness of any engine is dependent upon constant valve-clearances, the authors describe in detail the method followed in the Franklin design to maintain at less than 0.003 in. any variation in clearance. A careful analysis is made for each part in the valve-gear mechanism that is affected by expansion.
1930-01-01
Technical Paper
300028
Oscar C. Bridgeman, Hobart S. White
The study of fuel flow in gravity-feed systems, which has hitherto been confined to flow through simple orifices, has been extended to include the measurement of flow through systems of various designs. The results of this study indicate that variations in the cross-sectional area of the feed lines from that at the tank outlet may have a marked effect on the vapor-locking tendency. Constrictions in the line and increases in cross-sectional area along the direction of flow are particularly liable to cause trouble from vapor lock. Experiments with commercial carbureters show that weathering of the gasoline in the carbureter float-bowl reduces the vapor-locking tendency of the fuel and, under certain conditions, may even cause an increase in the flow through the jet.
1930-01-01
Technical Paper
300023
H. K. CUMMINGS
THIS paper was prompted by the numerous inquiries received by the Bureau of Standards from airplane owners and airport operators regarding the grades of gasoline that are suitable for aircraft use and the suggestion that the Bureau test all brands of commercial aviation gasoline and publish the results or that the Department of Commerce issue approved type certificates for certain standard grades of aviation gasoline. The purpose of the author in presenting the paper was to open discussion on the subject, and in this he was very successful. The problem of a suitable fuel and its general distribution throughout the Country for aviation use is complicated by considerable divergence of opinion among aircraft-engine manufacturers as to the kind of fuel preferred and by wide differences in detonation characteristics of gasolines of like volatility.
1930-01-01
Technical Paper
300024
S. D. Heron
FUELS for use in aircraft engines are discussed with reference to their antiknock value, volatility, vapor-locking and engine-starting properties, gum content and availability, and to antiknock agents. The usefulness of a fuel for spark-ignition engines is stated to be limited by its tendency to heat the cylinder and the piston unit. Definite evidence is available that the tendency of fuels to heat the cylinder unit is not always in accord with their tendency to cause audible knocking. The fuel required depends upon the compression ratio of the engine, its volumetric efficiency, the design, size and temperature of the cylinder unit, and the rate of revolution. Mid-Continent Domestic Aviation gasoline having an approximate antiknock value of 50 octane-50 heptane gives excellent results if the engine output is kept within the limitations of this fuel but is not suitable for many modern aircraft engines if flown wide open at sea level.
1930-01-01
Technical Paper
300015
H. D. Hill
Attention is drawn to the difference in method of procedure necessary in developing large and small Diesel engines and to the greater obstacles met in systems injecting the charge directly to the cylinder in comparison with those employing precombustion-chambers. The antechamber fuel system used in the Hill engine is described as performing three functions: (α) to ignite and eject rich fuel gas into the main combustion space early in the combustion stroke; (b) to feed the cylinder combustion with air from the upper portion of the antechamber after the main part of the fuel charge has been ejected from the chamber; and (c) to cause violent turbulence and complete mixture of the charge by the large stream of gas issuing from the antechamber. Only the first of these three functions is accomplished by the ordinary precombustion-chamber. A recently developed automotive-type engine is described. Discussion of this paper and C. L.
1930-01-01
Technical Paper
300014
C. L. CUMMINS
EXPERIENCE with a large sedan and a roadster in which the original eight-cylinder engine had been replaced by a four-cylinder Diesel engine is recounted in the first part of this paper, including road driving and establishing an official speed record of 80.389 m.p.h. at Daytona Beach, Fla. Then follows a description of the metering, injection and combustion processes of the Cummins engine, which are distinguished principally by the separation of the metering and injection operations so that the former is done at low pressure and the fuel is preheated and aerated before injection. Turbulence is caused and sooting of the injector orifices is prevented by the action of an air bottle in the piston-head. Discussion of this paper and H. D. Hill's paper on Small Diesel Engines will be found beginning on p. 290 of the September, 1930, issue of the S.A.E. JOURNAL.
1930-01-01
Technical Paper
300010
FRANK JARDINE
1930-01-01
Technical Paper
300013
E. C. MAGDEBURGER
THIS paper, which was presented at meetings of the Buffalo and Pennsylvania Sections, begins with a statement of the advantages sought in adapting the Diesel cycle and developing oil engines to operate at high rotative speeds. Oil engines are classified according to their means for injecting and burning the fuel, and disadvantages attributed to the various systems are listed. Then follow descriptions of a number of engines of the different classes, selected according to the contribution their designs have made to the art. Particular attention is given to provisions for metering the fuel and for supercharging, which latter is said to have the same object as increasing the speed. Discussion* at the Buffalo meeting was on general problems of lubrication and fuel, on other methods for securing power from fuel oil, and on economic comparison of gasoline and oil engines.
1930-01-01
Technical Paper
300007
ALEX TAUB
HOPING that discussion and dissemination of information on the fundamentals of distribution routine will continue, the author reiterates known facts, which include (a) the method of charting distribution progress, (b) a suggestion for locating the error in distribution and (c) a series of thoughts on construction. The paper is divided into two parts, the first being a study of distribution routine and the other a discussion of a few of the problems that are met every day in the search for perfect distribution. Complete satisfactory distribution and the quantitative measurement of its quality are the two major problems of distribution. The interrelation of these problems is mentioned and the complexity of the subject of distribution is emphasized by listing nine detailed factors, the point being made that if the information that engineers have on these items could be collected and codified considerable progress would be made.
1930-01-01
Technical Paper
300009
Clarence S. Bruce
MARKING the completion of the investigation of engine acceleration in connection with a study of the economic volatility of motor fuels that has been under way since 1920, the paper is in the nature of a final progress-report and presents a summary of the results obtained. The earlier work done is reviewed briefly, following which the phase of the work that the paper covers, comparisons of fuel performance with downdraft and updraft induction-systems and with three separate carbureters connected by short pipes to the three intake ports of the engine, is described. Although the latter arrangement roughly represents cold carburetion, complete parallelism with the other series of tests is not possible since the three carbureters were not equipped with accelerating-charge pumps. The effect of the accelerating-charge pump was brought out in the discussion, a car so equipped traveling 160 ft. in 6 sec., while other cars of the same make but not fitted with the pump required 0.2 sec. more.
1930-01-01
Technical Paper
300008
D. B. BROOKS, C. S. BRUCE
THIS REPORT covers tests made at the laboratory of several automobile companies to ascertain the effect of engine design and of different fuels on the acceleration characteristics of a number of different engines. The work was authorized by the Cooperative Fuel Research Steering Committee as an extension of the program of fuel research because the tests on fuel volatility and engine acceleration made by the Bureau of Standards were all made on one engine. The present report describes the types of manifold and manifold jacketing used on the six and eight-cylinder engines and the conditions under which tests were made with three fuels supplied by the Bureau. Results of uniform acceleration tests on seven engines are given and discussed.
1930-01-01
Technical Paper
300005
Alex Taub
PREVIOUS papers on Combustion-Chamber Design by three leading authorities on the subject showed enough points of real or apparent disagreement to leave the designing engineer in doubt on many of the details of design which they discussed. The author of this paper was asked to make a study of the works of these three authorities to discover points of agreement and clarify the subject for the benefit of engineers in general. Requests were made that each of the three authors in question furnish a list of his writings to be considered in this connection. Such lists were received from Mr. Ricardo and Mr. Janeway, but not from Mr. Whatmough in time for use in preparing the original paper. After the paper was delivered, a letter was received from Mr. Whatmough, and revisions in the paper have been made on the basis of that letter. Credit is given to Mr. Ricardo for initiating the study of combustion-chambers and inspiring other workers.
1930-01-01
Technical Paper
300004
Alex Taub
AN ENDEAVOR is made herein by the author to prove by argument and charts based on data that the greatest result per dollar of car cost is obtained by the greatest piston displacement obtainable per dollar expended rather than by the greatest horsepower per dollar. Maximum result per dollar is a major principle of economics, but horsepower per dollar and piston displacement per dollar are controversial economic fundamentals. The latter is declared to be the accepted principle in the low-price car field, and the author asserts that it should be accepted in the high-price field. Price class controls the cost of the powerplant, and ingenuity of the engineering and manufacturing departments will control piston displacement. The trends in the different price classes as regards car weight, piston displacement, ratio of weight to piston displacement, and potential and actual performance in the items of economy, durability, acceleration and speed, are shown by charts and discussed.
1930-01-01
Technical Paper
300037
ARTHUR NUTT
THE PAPER urges united cooperation instead of the present division of responsibility between the engine designer and the airplane designer in the installation of aircraft engines. The tubular rings upon which engines are commonly mounted are usually supported by structural members that are welded to the ring and attached to the fuselage at the four longitudinals. Inaccuracy is common in these structures, and many of them lack sufficient stiffness. Gravity gasoline-feed is recommended for its simplicity, provided the pressure head required by the carbureter can be secured, but the author reports having seen an installation in which the engine would operate so long as the airplane had its tail on the ground, yet the engine would die as soon as the tail was raised during a take-off. The use of gasoline-resisting rubber-hose with metal liners and the avoidance of sharp bends are recommended for the gasoline connections.
1930-01-01
Technical Paper
300034
L.M. WOOLSON