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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

SPRINGS AND SPRING SUSPENSIONS

1920-01-01
200004
The chief factors affecting the riding quality of a motor vehicle are spring deflection, or amplitude; periodicity, or the number of vibrations per second; and the proportion of the sprung to the unsprung weight. Other factors are the wheelbase, the tread, the height of the center of gravity of the car and the effect of the front springs on the rear ones. The three main factors are considered at some length, various experiments being described and illustrated by diagrams. Spring inertia and the fundamentals of periodicity are then investigated, by experiments and mathematical analyses, in considerable detail.
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

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

HIGH-SPEED INDICATORS

1920-01-01
200011
The indicator was an important factor in the early development of the internal-combustion engine when engine speeds were low, but on high-speed engines such indicators were unable to reliably reproduce records because of the inertia effects of the moving part of the pressure element. The first need is for a purely qualitative indicator of the so-called optical type, to secure a complete and instantaneous mental picture of the pressure events of the cycle; the second need is for a purely quantitative instrument for obtaining an exact record of pressures. The common requirements for both are that the indicator timing shall correctly follow the positions of the crank and that the pressure recorded shall agree with the pressures developed within the combustion space. Following a discussion of these requirements, the author then describes the demonstration made of two high-speed indicators, inclusive of various illustrations that show the apparatus, and comments upon its performance.
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

ADAPTING TRUCK AND TRACTOR ENGINES TO MOTOR-BOAT USE

1920-01-01
200021
The automobile engine, as used in passenger cars and a large percentage of trucks, is not adapted to use in motor boats. It is not built substantially enough for this, inasmuch as the power output of the motor-boat engine, except during starting or landing, is always 100 per cent. In view of this and because tractor, truck and marine engines are of the same family, it appears that if a truck or tractor engine were made with 100 per cent continuous power output capacity it would be satisfactory for marine use. The author describes and illustrates a tractor engine modified for marine use. The lubrication system of this engine is explained. The respective merits of right and left-hand engines are discussed. It is stated in a twin-screw boat that it is unnecessary to have both engines run out-board; that both can turn in the same direction without causing material difference in results.
Technical Paper

THE DIESEL ENGINE OF THE GERMAN SUBMARINE U-117

1920-01-01
200020
Shortly after the armistice, the author witnessed the surrender of the German submarine fleet and subsequently inspected 40 of the 170 submarines first surrendered. He also inspected 185 submarines in Germany. Practically all the engines were of the Machinenfabrik Ausburg-Nürnburg four-cycle Diesel type, of 300, 550, 1200 and 1750 hp. There were but five Krupp two-cycle engines. Brief comment is made regarding the design of these engines. The author, who supervised the dismantling of the German submarine U-117 at the Philadelphia Navy Yard, gives a detailed description of its engines, which were of the 1200-hp. type. This includes comments regarding materials, design details, valve mechanism, starting and reversing gear, lubrication, cooling and accuracy of workmanship. The air-compression system and some of its auxiliaries are outlined.
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

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.
Technical Paper

IGNITION FROM THE ENGINEMAN'S VIEWPOINT

1920-01-01
200071
Ignition is discussed in a broad and non-technical way. The definition of the word ignition should be broad enough to include the complete functioning of the ignition apparatus, beginning from the point where mechanical energy is absorbed to generate current and ending with the completion of the working stroke of the engine. The ignition system includes the mechanical drive to the magneto or generator and the task imposed on the system is by no means completed when a spark has passed over the gap of the spark-plug. Ignition means the complete burning of the charge of gas in the cylinder at top dead-center, at the time the working stroke of the piston commences. The means employed to accomplish this result is the ignition system. In the present-day type of gasoline engine a spark produced by high-voltage electricity is almost universally used for ignition. This high-voltage electricity is produced by a transformer.
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