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Technical Paper

PROPER UTILIZATION OF NATURAL GASOLINE1

1923-01-01
230010
The term “natural gasoline” has been accepted generally by the petroleum industry as applying to the gasoline product extracted by any process from natural gas. Two processes are in use. The older one is the compression process applied to casinghead gas, which is produced from the oil-bearing sands of oil wells and carries vapors from the oil with which it has been in contact. This process of subjecting the relatively rich gas to a high pressure and then cooling it to or below atmospheric pressure, results in the direct condensation of gasoline which is weathered later to remove the “wild” unusable vapors. The later method is the absorption process in which the gas is brought into contact with a heavy oil, originally of no gasoline-content, which absorbs the gasoline. The enriched oil is then heated to distill off the gasoline, and these two operations of absorption and distillation are repeated continuously within a closed system.
Technical Paper

AIR-COOLED AUTOMOTIVE ENGINES

1923-01-01
230037
The author believes that the universal power unit will be direct air-cooled, but states that the direct air-cooled engine is now in the minority because, until very recently, there has not been a sufficiently broad series of established engineering facts and development work available to form a foundation for improvement. The satisfactory air-cooling of an 8 x 10-in. cylinder has been reported, and the development in a smaller cylinder of 138 lb. per sq. in. brake mean effective pressure; also, in a three-cylinder, air-cooled, radial-engine, a brake mean effective pressure of more than 125 lb. per sq. in. was developed and the engine endured beyond the ordinary expectations for water-cooled engines.
Technical Paper

TESTING FUELS FOR HIGH-COMPRESSION ENGINES

1923-01-01
230003
This Annual Meeting paper is concerned with certain of the methods used and results obtained in two investigations of fuels for high-compression aviation engines. The fuels in question are benzol and ethyl alcohol, either alone or as blended with gasoline. The necessity of mixture-ratio runs in fuel investigations is vigorously emphasized. In that the tendencies of a fuel to detonate or preignite limit the conditions under which it may be used, methods of estimating these characteristics are discussed. Also a graphical representation has been made to illustrate the relation between compression pressure, compression-ratio, volumetric efficiency and indicated power in order that, with a given engine, the effect on detonation of changing engine conditions may be estimated. Results characterizing the performance of the different fuels are mentioned and particular attention is directed to cases where these results are in contrast with current opinion.
Technical Paper

LAWS GOVERNING GASEOUS DETONATION

1923-01-01
230004
The authors present in this paper an explanation of gaseous detonation based upon what are considered incontrovertible laws, and show by the functioning of these well understood natural laws that gaseous detonation is a phenomenon that does not require any hypothetical assumptions to account for its existence. The physical conditions that must exist within an enclosed container when it is filled with an explosive mixture of gases and these gases are ignited are stated and analyzed mathematically, and an application of this analysis is made to the internal-combustion engine. The apparatus and the procedure are described inclusive of photographs and charts, and it is shown how the formulas can be applied (a) for constant throttle, by varying the temperature of the entering charge and (b) for constant temperature, by varying the throttle opening and the compression-ratio. The results are illustrated and discussed in some detail.
Technical Paper

MOLECULAR MOVEMENTS DURING COMBUSTION IN CLOSED SYSTEMS

1922-01-01
220002
The paper is an exposition of the theoretical analysis made by the author of the experimental work of Woodbury, Canby and Lewis, on the Nature of Flame Movement in a Closed Cylinder, the results of which were published in THE TRANSACTIONS for the first half of 1921. No experimental evidence is presented by the author that has not been derived previously by other investigators. The relation of pressure to flame travel is derived first, the relation of mass burned is considered and a displacement diagram constructed, described and analyzed. The break of the flame-front curve, called the “point of arrest,” enters prominently into the discussion and computations; the pressure in the flame-front is studied; the reaction-velocities are calculated; and general comments are made.
Technical Paper

THE MECHANISM OF LUBRICATION

1922-01-01
220008
The authors state that the coefficient of friction between two rubbing surfaces is influenced by a very large number of variables, the most important being, in the case of an oiled journal, the nature and the shape of the surfaces, their smoothness, the clearance between the journal and the bearing, the viscosity of the oil, the “film-forming” tendency or “oiliness” of the oil, the speed of rubbing, the pressure on the bearing, the method of supplying the lubricant and the temperature. The primary object of the paper is to present the best available data regarding the fundamental mechanism of lubrication so as to afford a basis for predicting the precise effect of these different variables under any specified conditions. Definitions of the terms used are given and the laws of fluid-film lubrication are discussed, theoretical curves for “ideal” bearings being treated at length.
Technical Paper

TEMPERATURES OF PNEUMATIC TRUCK-TIRES

1922-01-01
220048
After pointing out that the operating temperature is a vital factor in the life of a pneumatic truck-tire, the author outlines an investigation that was conducted at the plant of the Goodyear Tire & Rubber Co. This sought to determine (a) the best means of measing tire temperatures; (b) the temperature effect of inflation-pressure, load, long runs, frequency of stops, and the sizes of the rim and the tire; (c) the temperature of various designs of tire; and (d) some suitable means of reducing large-tire temperatures. The main reason for the rise in the temperature of a tire is stated to be the generation of heat resulting from rapid flexing; and the various factors having to do with this generation of heat and its dissipation to the atmosphere are listed. The laboratory testing-machine and the methods and apparatus employed to measure the temperatures are described.
Technical Paper

EUROPEAN AND AMERICAN AUTOMOBILE PRACTICE COMPARED

1921-01-01
210054
The paper surveys the differences between American and European conditions in the automotive industry and then considers briefly the reasons for them. The governing conditions are stated and their effects are traced. The subjects discussed include motorcycles and small cars, road conditions, car idiosyncracies, selling conditions in Europe, and a comparison of design in general. The differences of practice are stated and commented upon. Six specific points are emphasized in the summary. The author states that the outlook for American cars the world over is seemingly good. In recent American designs, equal compression - volumes are often assured by machining the heads; six-cylinder crankshafts have seven bearings and are finished all over in the circular grinding machine; pressure lubrication is used for all moving parts of the engine; and in all ways the highest practice is aimed at. America is trying to improve the quality without increasing the cost.
Technical Paper

THE NATURE OF FLAME MOVEMENT IN A CLOSED CYLINDER

1921-01-01
210026
The nature of flame propagation in an automobile engine cylinder has, for some time, been the subject of much discussion and speculation. However, very little experimental work has been done on flame movement in closed cylinders with a view to applying the knowledge directly to the internal-combustion engine. It has become recognized that knocking is one great difficulty which attends the use of the higher-boiling paraffin hydrocarbons, such as kerosene, and that knocking is one of the major difficulties to be overcome in designing higher-compression and hence more efficient engines. It was desirable, therefore, to determine, if possible, the nature and cause of the so-called fuel knock in an internal-combustion engine. The work described in this paper was undertaken to determine the characteristic flame movement of these various fuels and the physical and chemical properties which influence this flame propagation.
Technical Paper

FLYING AN AIRPLANE ENGINE ON THE GROUND

1920-01-01
200027
The very complete laboratory tests of airplane engines at ground level were of little aid in predicting performance with the reduced air pressures and temperatures met in flight. On the other hand, it was well-nigh impossible in a flight test to carry sufficient apparatus to measure the engine performance with anything like the desired completeness. The need clearly was to bring altitude conditions to the laboratory where adequate experimental apparatus was available and, to make this possible, the altitude chamber of the dynamometer laboratory at the Bureau of Standards was constructed. The two general classes of engine testing are to determine how good an engine is and how it can be improved, the latter including research and development work.
Technical Paper

SOME FACTORS OF ENGINE PERFORMANCE

1920-01-01
200042
A large number of tests were made in the altitude laboratory of the Bureau of Standards, using aircraft engines. The complete analysis of these tests was conducted under the direction of the Powerplants Committee of the National Advisory Committee for Aeronautics. Many of the engines were of the same make, differing in compression ratio or dimensions. The testing program included determinations of the brake-horsepower at various speeds and altitudes, or air densities, and the friction power, or the power required to operate the engine with no fuel or ignition at various speeds and air densities, with normal operating conditions of oil, water and the like. Some tests included determination of the effect of change of mixture ratio and of air temperature, and of different oils. The difficulties caused by the necessity of using indirect methods to ascertain the effect of various factors are outlined. The test analyses and curves are presented.
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

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

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

PROBABLE EFFECT ON AUTOMOBILE DESIGN OF EXPERIENCE WITH WAR AIRPLANES

1919-01-01
190007
THE impression that recent aircraft experience should have taught engineers how to revolutionize automobile construction and performance, is not warranted by the facts involved. Aircraft and automobiles both embody powerplants, transmission mechanisms, running gear, bodies and controls, but their functions are entirely different. The controls of an airplane, except in work on the ground, act upon a gas, whereas with an automobile the resistant medium is a relatively solid surface. Similarly, the prime function of the fuselage is strength, weight considerations resulting in paying scant attention to comfort and convenience, which are the first requirements of an automobile body. Aircraft running-gear is designed for landing on special fields, and is not in use the major portion of the time. The running-gear is the backbone of an automobile, in use continuously for support, propulsion and steering; hence its utterly different design.
Technical Paper

AN INTERPRETATION OF THE ENGINE-FUEL SITUATION

1919-01-01
190013
THE automotive industry is developing without due regard to the fuel situation. This situation is an integral part of the automotive field and should not be left out of account. Owing to the pressure of automotive demand, the supply of engine fuel is changing in character and price, with danger of precipitant alterations; there arises in consequence a fuel problem which cannot be adequately solved without the active participation of the automotive industry.
Technical Paper

HEAVY-FUEL CARBURETER-TYPE ENGINES FOR VEHICLES

1919-01-01
190069
Manufacturers of carbureters and ignition devices are called upon to assist in overcoming troubles caused by the inclusion of too many heavy fractions in automobile fuels. So far as completely satisfactory running is concerned, the difficulty of the problem with straight petroleum distillates is caused by the heaviest fraction present in appreciable quantity. The problems are involved in the starting, carburetion, distribution and combustion. An engine is really started only when all its parts have the same temperatures as exist in normal running, and when it accelerates in a normal manner. Two available methods, (a) installing a two-fuel carbureter, using a very volatile fuel to start and warm-up the engine, and (b) heating the engine before cranking by a burner designed to use the heavier fuel, are described and discussed.
Technical Paper

SOME ESSENTIAL FEATURES OF HIGH SPEED ENGINES

1917-01-01
170004
The author outlines methods for producing high-speed engines with high mean effective pressure and gives data resulting from several years' experimental work. He discusses the desirable stroke-bore ratios; valve area, weight, dimensions, location and timing; compression ratios; ignition requirements; and the location and means for operating camshafts and other valve-actuating mechanism. Data are given regarding the best material and dimensions for pistons and the desirable number of rings. The physical characteristics of alloy steel desirable for use in connecting-rods are mentioned. Similar data, including dimensions and factors controlling the construction of the crankshaft and its bearings are included. The relation of the inertia stresses set up by reciprocating parts to those due to the explosion and compression pressure on the piston head is indicated, and the maximum total stress deduced.
Technical Paper

DYNAMIC BALANCING OF ROTATING PARTS

1917-01-01
170005
The author points out the necessity of obtaining dynamic or running balance of rotating parts, especially in automobile-engine construction. He discusses the manifestations of the lack of static and running balance, such as vibration and high bearing pressures. Formulas are supplied for calculating bending moments and centrifugal forces in a crankshaft that is out of balance. Methods for obtaining static balance are described and the possible conditions existing after static balance is obtained are treated, with especial reference to the existence of one or more couples. Descriptions are given of two representative machines that are used to locate couples and correct for them. The principles of operation are made clear and advantages and disadvantages of each type are brought out fully.
Technical Paper

AVIATION ENGINE DEVELOPMENT

1917-01-01
170042
This paper first traces the early development of aviation engines in various countries. The six-cylinder Mercedes, V-type twelve-cylinder Renault, and six-cylinder Benz engines are then described in detail and illustrated. Various types of Sunbeam, Curtiss, and Austro-Daimler are also described. The effect of offset crankshafts, as employed on the Benz and Austro-Daimler engines, is illustrated by pressure and inertia diagrams and by textual description. The paper concludes with a section on the requirements as to size of aviation engines, four curves showing the changing conditions which affect the engine size requirements. These curves relate to variations of temperature, air density, engine speed, airplane speed and compression ratio required to compensate for decrease in air density, all as related to varying altitude.
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