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Technical Paper

CYLINDER ACTIONS IN GAS AND GASOLINE ENGINES

1921-01-01
210043
The distinguished author begins with a short account of the principal actions common to all internal-combustion engines and then proceeds to a more detailed account of the experiments that have been made to develop the theory and establish the properties of the flame working fluid of those engines. The divisions of the paper are headed (a) short statement of cylinder actions, (b) the air standard, (c) flame, the actual working fluid, (d) knocking, pinking and detonating, (e) air and exhaust supercompression, (f) residual turbulence, (g) gaseous explosions, (h) flame propagation and recompression, (i) the specific heat of flame, and (j) conclusions. After treating (a) in considerable detail, the author discusses present efficiencies and knowledge in regard to the limits of the thermal efficiency possible in internal-combustion engines under (b), (c), (d) and (e), going into considerable detail and presenting and analyzing numerous diagrams and charts.
Technical Paper

THE PACKARD FUELIZER

1921-01-01
210037
The general requirements for ideal carburetion are considered first, as an introduction to what the Packard fuelizer is and how it functions. Since it is difficult to secure uniform distribution with what is termed a wet mixture, this problem is discussed in general terms and it is stated that the fuelizer was evolved only after several different types of exhaust-heated manifold had been tested and found wanting. Detonation is treated at some length, four specific rules being stated that apply to the most desirable mixture temperatures to be maintained, and the source of the ignition spark for the fuelizer is discussed as an important element in the device. Further consideration includes comments upon the comparative merits of the hot-spot and the fuelizer, “hot-spot” being intended to mean any of the exhaust-heated manifold-designs in which the heat is more or less localized.
Technical Paper

HIGH-SPEED ENGINES OF SMALL PISTON DISPLACEMENT

1921-01-01
210039
In addition to using a smaller quantity of fuel per horsepower-hour, the small high-speed internal-combustion engine has other important features of advantage which are stated. The authors outline specifications intended to secure these advantages. The high-speed racing engine designed by the authors, which won the 500-mile race on the Indianapolis Speedway in 1920, is illustrated and described in detail, its distinctive features being commented upon. The automobile should be built to a higher standard for the use of the high-speed engine. The builder should work to a greater degree of precision and, as the working parts of the engine are all light and stressed fairly highly, this necessitates the use of properly heat-treated high-grade materials. Few small cars of this type seem to give satisfaction. The authors look for further developments to counteract this in the near future.
Technical Paper

BETTERING THE EFFICIENCY OF EXISTING ENGINES

1920-01-01
200005
First reviewing the history of the progressive insufficiency of the supply of highly volatile internal-combustion engine fuels and the early efforts made to overcome this by applying heat to produce rapid vaporization, the author gives an outline of the methods already found valuable in offsetting the rising boiling points of engine fuels and states the resulting three-fold problem now confronting the automotive industry. The tendency to subordinate efficient vaporization to the attainment of maximum volumetric efficiency is criticised at some length and the volatility of fuel is discussed in detail, with reference to characteristic distillation, time of evaporation and distillation-temperature curves which are analyzed. Heating devices are then divided into four classes and described, consideration then being given to fuel losses outside the engine.
Technical Paper

DILUTION OF ENGINE LUBRICANTS BY FUEL

1920-01-01
200008
Engine lubrication troubles resulting from the dilution of the lubricating oil in engine crankcases appear with increasing frequency, particularly where economy demands the use of cheap grades of fuel. Unless a lubricant not miscible with present engine fuels can be produced, lubricants will steadily decrease in viscosity whenever fuel finds its way into them. The most satisfactory remedy is to prevent dilution of the oil. To prevent absorption of the fuel by the oil is a problem of engine design. In experiments made by the Bureau of Standards the absorption of fuel vapors at average engine temperatures was found to be negligible; further experiments and oil tests showed no indication of dilution due to cracking, with representative refiners' products from typical crude oils available in this country.
Technical Paper

ALUMINUM PISTON DESIGN

1920-01-01
200006
The two broad divisions of aluminum pistons from a thermal standpoint are those designed to conduct the heat from the head into the skirt and thence into the cylinder walls, and those designed to partly insulate the skirt from the heat of the piston head. Pistons of the first type seem logical for heavy-duty engines; those of the second type are better suited for passenger-car engines. The objections of wear, piston slap, excessive oil consumption and crankcase dilution are stated as being the same for aluminum as for cast-iron pistons; and these statements are amplified. Piston slap is next considered and, as this can be overcome by using proper clearance, pistons of the second design tend to make this condition easier to meet. Many tests show that when too much oil is thrown into the cylinder bores, tight-fitting pistons and special rings will not completely overcome excessive oil consumption.
Technical Paper

SUPERCHARGERS AND SUPERCHARGING ENGINES

1920-01-01
200007
If at great altitudes air is supplied to the carbureter of an engine at sea-level pressure, the power developed becomes approximately the same as when the engine is running at sea level. The low atmospheric pressure and density at great altitudes offer greatly reduced resistance to high airplane speeds; hence the same power that will drive a plane at a given speed at sea level will drive it much faster at great altitudes and with approximately the same consumption of fuel per horsepower-hour. Supercharging means forcing in a charge of greater volume than that normally drawn into the cylinders by the suction of the pistons. Superchargers usually take the form of a mechanical blower or pump and the various forms of supercharger are mentioned and commented upon. Questions regarding the best location for the carbureter in supercharged engines are then considered.
Technical Paper

COMPOSITE FUELS

1920-01-01
200012
The progressive decrease in the volatility of gasoline due to the insufficiency of the high-volatility supply has developed a problem of efficient utilization of internal-combustion-engine fuel that requires coordination between the engine and its fuel and a technical as well as economic adjustment between supply and demand. The three channels through which this adjustment tends toward accomplishment are stated and commented upon, consideration then passing to the three main resources from which the components of composite fuels can be drawn.
Technical Paper

TENDENCIES IN ENGINE DESIGN

1920-01-01
200013
War service demanded that gasoline engines be absolutely reliable in minor as well as major details of construction; lightness of construction was second in importance. The war scope of the gasoline engine was so wide that engineers were forced toward the solution of unexpected and unrealized problems and a vast amount of valuable data resulted. This information includes recent determination of the quantitative nature of the factors governing thermodynamic performance in respect to mean effective pressure, compression ratio and the effect of volumetric efficiency; mechanical performance in regard to mechanical efficiency and internal friction; and engine balancing.
Technical Paper

THE VELOCITY OF FLAME PROPAGATION IN ENGINE CYLINDERS

1920-01-01
200010
Flame propagation has received much attention, but few results directly applicable to operating conditions have been obtained. The paper describes a method devised for measuring the rate of flame propagation in gaseous mixtures and some experiments made to coordinate the phenomena with the important factors entering into engine operation; it depends upon the fact that bodies at a high temperature ionize the space about them, the bodies being either inert substances or burning gases. Experiments were made which showed that across a spark-gap in an atmosphere of compressed gas, as in an engine cylinder, a potential difference can be maintained which is just below the breakdown potential in the compressed gas before ignition but which is sufficient to arc the gap after ignition has taken place and the flame has supplied ionization. These experiments and the recording of the results photographically are described.
Technical Paper

ADAPTING ENGINES TO THE USE OF AVAILABLE FUELS

1920-01-01
200017
Some of the salient facts regarding the character of the engine fuel marketed within the past few years are shown in accompanying curves. The desirability of operating present-day experimental cars with fuel that is the equivalent of fuel that will probably be generally marketed two years hence is stated and various methods of meeting the fuel problem are then examined. A dry fuel mixture is desired to prevent spark-plug fouling, to improve engine performance in cold weather and to minimize lubricating oil contamination by fuel which passes the pistons. Various methods of obtaining a dry mixture are then discussed, leading to a detailed description of the construction and operation of a device specially designed to accomplish such a result more successfully.
Technical Paper

NEEDS IN ENGINE DESIGN

1920-01-01
200016
The author advocates the use of the fragile aluminum crankcase as a spacer, running crankshaft bearing bolts clear through the crankcase and the cylinder base, so tieing the bearings firmly to the castiron cylinder-block and using the through-bolts also as holding-down studs for the cylinders. The results of experiments on six-cylinder engines with reference to the satisfactory utilization of engine fuel now on the market are then presented. The problem is how to carry the fuel mixture in a proper gaseous state from the carbureter into the cylinder without having the fuel deposited out meanwhile. The power developed at engine speeds of 400 to 2800 r.p.m., with and without hot air applied to the carbureter, is tabulated, the proper location of the intake manifold is discussed, and the necessary features of a satisfactory engine to utilize present-day fuel are summarized.
Technical Paper

STEAM AUTOMOTIVE SYSTEM

1920-01-01
200014
It is stated that the general performance of the steam-propelled automobile has never been equalled by that of the most highly-developed multiple-cylinder gasoline cars and that it is significant that no innovation in the gasoline car has yet been able to give steam-car performance. This led to an effort to remove the troublesome features of the steam car, rather than to complicate the gasoline car further by attempting to make it duplicate steam-car performance. The paper describes in detail the steam automotive system developed by the author and E. C. Newcomb, including the boiler, the combustion system and its control, the engine and the condensing system.
Technical Paper

PREIGNITION AND SPARK-PLUGS

1920-01-01
200015
The author proposes to determine what features of spark-plug construction cause preignition and how this preignition manifests itself. To this end observed conditions on an Hispano-Suiza aviation engine following 4 hr. of an intended 6-hr. run are reported, with supplementary tests and observations. This resulted in experiments made to determine the cause of preignition, using spark-plugs constructed so that different features of their design were exaggerated. Illustrations of these plugs are shown and the results obtained from their tests are described. The different observed peculiarities are then stated, analyzed and compared with normal spark-plug performance. The experiments serve as a means of identification of special forms of preignition and as an indication of the abnormally high temperatures to which valves and combustion-chamber walls are thus subjected.
Technical Paper

COMMENTS UPON FUELS, LUBRICANTS, ENGINE AND PISTON PERFORMANCE

1920-01-01
200019
The comments the author makes regarding fuels, lubricants and engine and piston performance are suggested by pertinent points appearing in papers presented at the 1920 Annual Meeting of the Society. A list of these papers is given. The subjects upon which comments are made include salability of a car, engine balancing, pressure and chemical constitution of gasoline at the instant of ignition, the use of aluminum pistons, the success attending the various departures from orthodox construction, gasoline deposition in the crankcase and cleanness of design, as stated by Mr. Pomeroy; the performance of a finely atomized mixture of liquid gasoline and air and the contamination of lubricating oil by the fuel which passes the pistons, as discussed by Mr. Vincent; the dilution of lubricating oil in engine crankcases and the saving that can be effected by its prevention, as mentioned by Mr. Kramer; and tight-fitting pistons and special rings as presented by Mr. Gunn.
Technical Paper

ENGINE SHAPE AS AFFECTING AIRPLANE OPERATION

1920-01-01
200025
The annual report covering transportation by the largest British air-transport company laid particular emphasis upon the greater value of the faster machines in its service. Granted that efficient loads can be carried, the expense, trouble and danger of the airplane are justified only when a load is carried at far greater speed than by any other means. A reasonable conclusion seems to be that we can judge the progress made in aviation largely by the increased speed attainable. It is interesting and possibly very valuable therefore to inquire into the relations of power and resistance as applied to small racing machines with aircraft engines that are available.
Technical Paper

DESIGN FACTORS FOR AIRPLANE RADIATORS

1920-01-01
200026
The paper defines properties that describe the performance of a radiator; states the effects on these properties of external conditions such as flying speed, atmospheric conditions and position of the radiator on the airplane; enumerates the effects of various features of design of the radiator core; and compares methods that have been proposed for controlling the cooling capacity at altitudes. Empirical equations and constants are given, wherever warranted by the information available.
Technical Paper

MID-WEST SECTION PAPERS HEAVY-DUTY HIGH-SPEED ENGINE

1920-01-01
200076
The feeling that a truly heavy-duty engine for truck and tractor service was not available led the company represented by the authors to commence the development of an engine that would be capable of high speed as well as have ability to develop maximum horsepower and torque at low or medium speeds. Five specific requirements are stated for a tractor and three for a truck engine; the requirements of a universal truck and tractor engine are then specified under six headings. The special features of design of the engine developed are described in minute detail and illustrated by photographs and charts, seven definite features being mentioned as having been productive of the desired results. The testing apparatus is described and power and torque curves, a timing diagram and capacity curves of the water and oil-pumps are presented. Gasoline was used as fuel, although the engine is designed to use either gasoline or kerosene and is said to be adapted to the use of the heavier fuels.
Technical Paper

PISTON-RINGS

1920-01-01
200075
The free, resilient, self-expanding, one-piece piston-ring is a product of strictly modern times. It belongs to the internal-combustion engine principally, although it is applicable to steam engines, air-compressors and pumps. Its present high state of perfection has been made possible only by the first-class material now available and the use of machine tools of precision. The author outlines the history of the gradual evolution of the modern piston-ring from the former piston-packing, giving illustrations, shows and comments upon the early types of steam pistons and then discusses piston-ring design. Piston-ring friction, the difficulties of producing rings that fit the cylinder perfectly and the shape of rings necessary to obtain approximately uniform radial pressure against the cylinder wall are considered at some length and illustrated by diagrams.
Technical Paper

THE CRITICAL SPEEDS OF TORSIONAL VIBRATION

1920-01-01
200072
Vibrations of several kinds can occur in crankshafts, but the principal ones are transverse and torsional; the paper deals entirely with the latter. A simple case of torsional vibration is considered first and the principles are applied to the torsional vibration of a shaft, the argument being carried forward at some length. A discussion of critical speeds follows and this is supplemented by a lengthy mathematical analysis, inclusive of diagrams. Calculations were made to determine the period of the shafting of United States submarines S4 to S13 and these are described. The three cases investigated include the charging condition when the engine is driving the dynamo, the after clutch being disconnected; the surface condition, when the engine drives the propeller; and the submerged condition, when the motors drive the propeller, the forward clutch being disconnected. Calculations were made also with a Sperry magnetic clutch substituted for the usual flywheel and clutch.
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