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Stating that asphalt, brick and concrete-slab road-surfaces are the only pavements that have given satisfaction for automobile traffic, the author believes further that thus far the concrete-slab surface is the only one worthy of consideration for such traffic. He discusses the merits and demerits of these surfaces and includes an enumeration of the factors that combine to produce a thoroughly satisfactory road surface. Passing to a detailed review of the bearing value of soils and the correction of road failures, the author presents data and illustrations in substantiation of his statements and follows this with a consideration of the reinforcing of a concrete road-slab with steel.

This paper is illuminative and affords an opportunity for better comprehension of the remarkable progress and accomplishment made in Europe along the lines of commercial aviation. Reviewing the present European routes now in regular or partial operation, the author stresses the essentialness of the attitude of the press in general being favorable if commercial aviation is to become wholly successful. The airship appears most practical for long-distance service, to the author, and he mentions the possibility of towns and cities growing up around “air ports.” The cost of airship travel is specified, although it is difficult to figure costs and necessary charges because so few data on the depreciation of equipment are available. Regarding successful operation, much depends upon the efficiency of the ground personnel and organization.

Stating that economy and performance are diametrically opposed in that the greater the performance demanded the less the economy is likely to be, the author mentions that the gasoline bill of the average user is not the major portion of his expense and asserts that economy is determined very largely by the engine design, the chassis design and the tires. The subject of engine design is outlined and consideration is given to acceleration during periods of coasting. Discussing briefly the chassis and the tires, attention is given to oil and tire economy, followed by statements regarding design from the viewpoint of service and performance as influenced by gear-ratios and gearshifting.

The paper describes the results obtained from making visual observations of the paths followed by the several portions of the air-stream. One of the passages being considered was half-sectioned in a plane about which the passage was symmetrical; that is, a plane containing the axes of the several parts of the passage. A flat glass plate was then cemented on to complete the half-passage. With the outlet end of such a passage connected to an engine intake, any sort of flow encountered in engine practice can be reproduced. By introducing gasoline with the entering air, a tracery of fine sharply defined lines on the glass is produced and this was photographed, as is described in detail. Varied shapes of passages were studied in this manner. These are illustrated and the variations in the results under differing conditions are discussed.

The author states that considerable thought has been devoted recently to the relation of fuel end-point to fuel economy. It has been shown that, provided an intimate mixture of fuel-vapor and air is secured, such a mixture will not condense at the ordinary temperatures of the intake. However, on the contrary, crankcase dilution, an excess of deposited carbon, low mileage per gallon of fuel and ignition trouble are being experienced. There appears to be a discrepancy between the efficiency that should be attained and what is actually attained. To investigate this the Bureau of Standards undertook a brief series of experiments to rough out a line of procedure. Regarding compression of a dry mixture, curves are shown to illustrate that gasoline vapor compresses when “dry.” Detonation was evident when using one spark-plug and there was no detonation when using two spark-plugs.

After stating that the meaning of the term “gasoline” seems to be generally misunderstood for the reason that it has been assumed that gasoline is, or ought to be, the name of a specific product, the author states that it is not and never has been a specific product and that although gasoline has a definite and generic meaning in the oil trade it has no specific meaning whatever. It means merely a light distillate from crude petroleum. Its degree of lightness, from what petroleum it is distilled and how it is distilled or refined are unspecified. Specifically, “gasoline” is the particular grade of gasoline which at a given moment is distributed in bulk at retail. It can be defined with reasonable precision as being the cheapest petroleum product acceptable for universal use as a fuel in the prevailing type of internal-combustion engine.

Two distinct problems are involved in fuel research work, multi-cylinder distribution and the chemical constitution of the fuel mixture after it enters an engine cylinder. In discussing elementary combustion, the author refers to the components of the energy of combustion as gravitational, kinetic and barometric, and elaborates his theme with the aid of diagrams and charts showing normal and abnormal combustion. After emphasizing the necessity of theorizing at some length, anti-knock substances are discussed, inclusive of substances apparently dissimilar that have the same chemical constituents. The ignition point and fuel utilization are treated, followed by comments upon fuel studies that have been made, with accompanying indicator-cards. The future objectives of fuel research are outlined as being along lines of physical and of thermo-chemistry, the simple laws of elementary physics, and cooperation with the producers and refiners of the fuel.

Two serious problems confront the automotive industry in connection with the present fuel shortage, the securing of a much higher degree of fuel economy with existing equipment and the matter of future designs. These problems are of nearly equal importance. Because its fuel bill constitutes the second greatest item of expense for the Fifth Avenue Coach Co., operating in New York City, it is constantly experimenting with devices of various kinds to improve fuel economy. Of the different devices that it has tested, the thermostatic temperature-control for the carbureter appears to afford greatest possibilities of saving, and the author presents the results of tests of this device in actual service on motor vehicles.

The data given in this paper were obtained from an investigation by the Bureau of Mines in cooperation with the New York and New Jersey State Bridge and Tunnel Commissioners to determine the average amount and composition of the exhaust gases from motor vehicles under operating conditions similar to those that will prevail in the Hudson River Vehicular Tunnel. A comprehensive set of road tests upon 101 motor vehicles including representative types of passenger cars and trucks was conducted, covering both winter and summer operating conditions. The cars tested were taken at random from those offered by private individuals, corporations and automobile dealers, and the tests were made without any change in carbureter or other adjustments. The results can therefore be taken as representative of motor vehicles as they are actually being operated on the streets at the various speeds and on grades that will prevail in the tunnel.

About 1917 the heavy ends of the fuel sold as gasoline required such an amount of heat to vaporize them that the expression “crankcase dilution” appeared; now they have increased to a maximum boiling-point of 446 deg. fahr., which has made it necessary to go still farther in the direction of heat application. After a brief consideration of the relative heat-absorption of air and fuel and the time factor in its relation to vaporizing, the author describes experiments with a specially designed manifold for increased vaporization efficiency and presents photographs of the device. With this type of manifold it has been possible to eliminate crankcase oil dilution completely and effect a reduction in carbonization. The lubrication efficiency has been improved, as well as other features that are enumerated.

Stating that the knowledge now available does not permit an exact scientific definition of flame and giving the reasons, in this paper the author regards flames as gases rendered temporarily visible by reason of chemical action, discusses their physical rather than their chemical aspects and, unless otherwise indicated, refers to the flames of common gasoline and kerosene only. To gain a reasonably clear understanding of the requirements and characteristics of the different kinds of flame, it is necessary to begin with a study of atoms and molecules. The author therefore discusses the present atomic theory, the shape of the atom and molecular structure, and follows this with a lengthy detailed description of the beginning of combustion. The requirements and characteristics of the inoffensive variety of combustion are considered next and nine specific remedies are given for use in accomplishing the burning of heavy fuels with a blue flame in present engines.

The paper analyzes and states the factors affecting the power requirements of cars as rubber-tired vehicles of transportation over roads and the factors affecting the amount of power supplied the car as fuel to produce at the road the power required for transportation. Quantitative values are given wherever possible to indicate the present knowledge of the relation between the factors involved, and the text is interspersed with numerous references, tables, charts and diagrams. Among other important factors specifically discussed are mixing and vaporization, charge quantity control, the heat of combustion, gas-pressure, transformation loss and power transmission efficiency. Six appendices contributed by other associates of the Bureau of Standards are included.

The author selects and sets forth some of the main laws and basic considerations influencing carbureter action. A brief defense of the carbureter as a means of supplying fuel to an engine is made, as compared with the fuel-injection method, and conditions in the cylinder, the manifold and the carbureter during normal operation are stated. The relations of throttle positions, manifold vacuum and engine torque are discussed, followed by an exposition of the effect of manifold vacuum upon vaporization. The subject of air-flow in carbureters is treated at some length and the venturi-tube form of air-passage is commented upon in considerable detail. The flow of air through air-valves, fuel-flow and mixture-proportion requirements are given detailed consideration, the last being inclusive of passenger-car, motor-truck, tractor, motorboat and airplane needs. The essentials for obtaining accurate information with regard to carbureter and engine tests are outlined.

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.

Before taking up the results of the tests, the author states briefly the provisions of the Nebraska tractor law, the kind of tests conducted and the equipment used. Applications covering 103 different tractors were received during the season; of the 68 that appeared for test, 39 went through without making any changes and 29 made changes. The results of the tests are described and illustrated by charts. The fuel consumption was studied from the three different angles of volumetric displacement, engine speed and the diameter of the cylinders, the tractors being classified accordingly and the results presented in charts which are analyzed. The weaknesses of the tractor as shown by the tests are commented upon at some length with a view to improvement of the product.

The author describes the development of an alcohol-burning tractor engine, after having stated a few of the fundamental requirements for burning alcohol economically and the results that can be attained by following them. The first trials were with 127-lb. gage compression at a normal operating speed. The problems attacked were those of what amount of heat applied to the mixture is desirable and its general effect on economy, output and operation; power output; general operation of the engine; and fuel consumption. The experimental work was done on a 4¼ x 6-in. four-cylinder 16-valve engine; this is described in detail and the results are presented in chart form. The conditions necessary for the proper use of alcohol as a fuel are discussed.

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.

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.

The author uses some analogies of mechanical things to illustrate the underlying facts that must be considered in connection with electrical ingition, the first being that of an automobile starting under the influence of a constant force, which is analogous mechanically to the old touch-spark ignition circuit in that the velocity of the automobile corresponds with the velocity or speed at which the electricity is moving through the circuit. In similar manner the analogy is extended to include car acceleration and its acquirement of a certain store of energy as an illustration of electrical-energy storage as the current through an induction-coil is increased; and further analogies are made, numerous diagrams being presented. Battery and magneto-ignition similarities are treated in a similar way, short and long sparks are discussed pro and con and spark lag is considered in general terms.

The author first considers the style and arrangement of the seats, the position of the rear axle as affecting the rear kick-up in the chassis frame, and the position of the rear wheels as determining the distance from the back of the front seat to a point where the curve of the rear fender cuts across the top edge of the chassis frame. The location of the driver's seat and of the steering-wheel are next considered, the discussion then passing to the requirements that affect the height of the body, the width of the rear seat, and the general shape. The evolution of the windshield is reviewed and present practice stated. Structural changes are then considered in relation to the artistic requirements, as regards the various effects obtained by varying the size or location of such details as windows, doors, moldings, panels, pillars, belt lines, etc., and the general lines necessary to produce an effect in keeping with the character of the car.