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The author views in perspective some facts from a purely scientific standpoint, and then shows their application to problems of the automotive industry. After reviewing the present facilities for measurement and the ability to make measurements of distances both infinitely small and large, as an aid toward a proper conception of the ultimate structure of matter, he applies this scientific knowledge in the direction of a solution of the fuel problem, which is a fundamental one because it involves the limitation of a natural resource. From 1918 and 1919 statistics, the amount of gasoline produced was something like 20 to 25 per cent of the crude oil pumped; 8 to 10 per cent is kerosene and 50 per cent is gas and fuel oil and a residue carrying lubricating oil, paraffin and carbon. Kerosene demand and production are practically fixed quantities; gasoline demands are increasing.

Kerosene has advanced to the front rank as a fuel for the farm tractor within a decade. A heavily preponderating majority of tractors burn kerosene. The history of early oil engines is reviewed and some comparative costs of kerosene and gasoline fuel for tractors, obtained from tests made in January, 1920, are given. Kerosene tractor-engine development is then discussed. The conditions required for complete combustion are the same in principle for both kerosene and gasoline, but in actual practice a wider latitude in providing ideal conditions is permissible for gasoline than for kerosene. The four classes of commercial liquid fuels usable in internal-combustion engines are the alcohols, the gasolines, the common kerosenes and the low-cost heavy-oil fuels. The alcohols rank lowest in heating value per pound of combustible. Under existing economic conditions neither alcohol nor the fuel oils require consideration as available fuels for the tractor.

The adoption of the present system of feeding a number of cylinders in succession through a common intake manifold was based upon the idea that the fuel mixture would consist of air impregnated or carbureted with hydrocarbon vapor, but if the original designers of internal-combustion engines had supposed that the fuel would not be vaporized, existing instead as a more or less fine spray in suspension in the incoming air, it is doubtful that they would have had the courage to construct an engine with this type of fuel intake. That present fuel does not readily change to hydrocarbon vapor in the intake manifold is indicated by tables of vapor density of the different paraffin series of hydrocarbon compounds.

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.

The development of the supercharger for aircraft engines has led to the possibility of hitherto unheard-of speed of transportation. An analysis of a definite case is presented to show the different aspects of the problem in a practical form, with a view toward determining what can reasonably be expected. An attempt is also made to arrive at a knowledge of the elements involved whose improvement will effect the greatest gain. The supercharger overcomes the deficiency of the ordinary gas engine's serious loss of power at great altitudes, due to its inability to obtain sufficient oxygen for the combustion of a normal charge of gas which, in an engine of conventional design, is essential to the development of its maximum output.

Although aluminum is the most abundant metal in the earth's crust, it was not until the early eighties that means were discovered for reducing it from its ores in such quantities and at such cost as to make it a commercial possibility. The world immediately began to find uses for this material. Two groups developed; one, assuming for aluminum properties that it did not possess, thought that it would in time replace all other metals; the other, which, reacting from the first-mentioned view due to failures and disappointments, thought it had little use. It was afterward realized that much research was necessary to make aluminum a really commercial metal. One of the main aims of the automobile engineer is to obtain lightness combined with proper strength. The paper deals with decreasing the weight of automobiles by more extended use of aluminum alloys. The physical properties of aluminum are described in considerable detail and its varied uses are enumerated.

The paper surveys the economic and engineering aspects of the automotive industry, so that engineers can align themselves with its future development. Better performance and longer life due to improved design and materials distinguish the 1920 car from its predecessors. One of the healthiest signs in the industry is the uniform determination of practically every manufacturer to improve the quality of his product. The designer has been forced to extend himself in getting the highest possible output from the smallest possible units. This trend is very noticeable. Conditions relating to prices, the return to peace-time production, the potential demand for cars and the present supply, and the probable improvements in cars are then reviewed, the thought then passing to a somewhat detailed discussion of detachable-head engines.

Design factors are considered from the thermodynamic standpoint only, which excludes several factors affecting power and economy. The problem of air heating includes a consideration of its influence on pressure, the consequent lowering of pressure being counteracted to some extent by the resulting improvements in carburetion and distribution and by more rapid and complete combustion; the effects of delayed combustion, with a study of the thermodynamic conditions and possible improvements; and the results that are actually obtainable from lean and rich fuel mixtures. Fuel economy is difficult because its factors conflict with those of power. The benefit of the expansion of any elastic working medium to economy is emphasized. Charts from previous papers, showing the ratio of air to fuel by weight, are referred to and discussed, best economy being obtained with mixtures leaner than those giving maximum power.

In investigating the forces that tend to break up and destroy roads, the most destructive of these being that of impact, the United States Bureau of Public Roads devised a method of receiving the impact of a truck on a small copper cylinder and determining its amount by measuring the deformation of the cylinder. The impact values are largely dependent upon the type and construction of the truck. Unsprung weights have a great influence upon the impact value of the blow on the road surface and a reverse influence upon the body of the truck; these effects are in two different directions. The present aim of the Bureau is to investigate this impact and the effect of the unsprung weight on the road. Most of the tests have been made on solid tires, a few have been made on worn solid tires and some on pneumatic tires. The Bureau intends to elaborate all of these tests, including different types of pneumatic tire, different unsprung weights and special wheels, such as cushion or spring wheels.

From a laboratory examination of the controlling relationships between carburetion and engine performance still in progress, the general conclusions so far reached include fuel metering characteristics, the physical structure of the charge, fuel combustion factors and details of engine design and manufacture. In every throttle-controlled engine, the variation in fuel metering for best utilization is inversely functional with the relative loading and with the compression ratio, but the nature of the fuel leaves these general relationships undisturbed. The physical structure of the charge influences largely the net engine performance and the order of variation of the best metering with change in load. Perfect homogeneity in the charge is theoretically desirable but entails losses in performance.

Supplementing a “more miles per gallon” movement in 1919, a series of experiments outlined by the S. A. E. Committee on Utilization of Present Fuels was undertaken by the Bureau of Standards, in May, 1920, which included measurements of engine performance under conditions of both steady running and rapid acceleration with different temperatures of the intake charge secured by supplying heated air to the carbureter from a hot-air stove, by maintaining a uniformly heated intake manifold and by using a hot-spot manifold, fuel economy being determined for both part and full-throttle operation. A typical six-cylinder engine was used, having a two-port intake manifold with a minimum length of passage within the cylinder block, an exhaust manifold conveniently located for installing special exhaust openings, rather high peak-load speed and conventional general design.

The farm tractor is finding itself among the most essential of mechanical agricultural devices; the industry is young, and controlling basic factors of design are not yet completely crystallized, nor has research had its proper share in the development. Some further factors of the author's earlier article on tractor plowing speeds2 are discussed in this paper. The earlier article dealt chiefly with plowing data on the assumption that there was delivered at the drawbar of the tractor a constant horsepower. This paper starts with a normal condition of a constant engine power which is to be delivered to the crankshaft under governor control for any of the travel speeds analyzed. The tractor is considered as powered by a given brake-horsepower engine, this power being transmitted through sets of gears in which the net bearing and gear efficiency is taken to be 73 per cent.

Two series of tests were made in 1918; one to determine whether the mixture giving best economy and that giving maximum power is a constant quality for all conditions of speed and power output; the other to ascertain what effect changes in the temperature of the fuel-intake system have on the quality of the mixture which gives the maximum power and that which gives best economy. The standard United States ambulance four-cylinder engine was used for these tests, its carbureter having a primary air passage, a primary fuel-jet, an auxiliary air passage with an air-valve and a secondary fuel-jet, the manifold being cast integrally with the cylinder block and a curved riser conducting the fuel mixture from the carbureter to it. The testing methods and fuel consumption measurements are described.

Continued lowering in the grade of fuel obtainable compels automotive engineers to produce engines that will utilize it with maximum economy. The manufacture of Pacific coast engine-distillate with an initial-distillation point of about 240 and an end-point of 480 deg. fahr. was abandoned by the principal oil companies early in 1920. Utilizing this fuel efficiently through its period of declining values forced advance solution of some fuel problems prior to a general lowering of grade of all automotive fuels.

The undisputed economy of the Diesel-type engine using heavy fuel oil is recognized, as no other power-generating unit of today shows better thermal efficiency. It is the result of the direct application of fuel in working cylinders. Transmission processes, such as the burning of fuel under a boiler to produce a working agent which must be carried to the prime mover, are less economical. The various factors which enter into a comparison between steam and heavy-oil installations are illustrated. The subject is treated in a more or less elementary manner. The diagrams and sketches are intended to explain the working principles of such examples of two and four-cycle engines as are now in actual operation in cargo ships, these being of the single-acting type. Double-acting and opposed-piston-type engines have been built and are being tried out. The working processes of two-cycle and four-cycle engines are illustrated and described in some detail, inclusive of critical comment.

Emphasizing the necessity of persuading fuel manufacturers to improve the suitability of internal-combustion engine fuel by the mixture of other materials with petroleum distillates, and realizing that efficiency is also dependent upon improved engine design, the author then states that results easily obtainable in the simplest forms of automotive engine when using fuel volatile at fairly low temperatures, must be considered in working out a future automotive fuel policy. The alternatives to this as they appear in the light of present knowledge are then stated, including design considerations. The principles that should be followed to obtain as good results as possible with heavy fuel in the conventional type of engine are then described. These include considerations of valve-timing and fuel distribution. Valve-timing should assist correct distribution, especially at the lower engine speeds.

THIS paper describes the various types of radiator installations in use. Tabulated data on several makes of radiation and on successful airplane radiator installations are given. A brief review of laboratory tests is made and the features to be considered in design and manufacture are discussed. The author concludes by cautioning engineers against attempting to base new designs entirely upon experimental data, without comparing the tentative design with existing successful installations.

THE ever-increasing demand for highly volatile fuels and constantly decreasing volatility, constitute a serious problem. Synthetic fuels have been suggested as a remedy, but these require a change in carburetion methods. It is the author's conviction that, if any redesigning is necessary, this should embody a combustion method by which any of the existing liquid hydrocarbons can be utilized and further change of method obviated, if a new fuel should later be developed. The high-compression engine is presented as a solution. Proof is offered that by its adoption any liquid hydrocarbon fuel can be utilized under any temperature condition and a real saving in fuel accomplished through increased thermal efficiency. Sustained effort should be made along these lines to increase thermal efficiency and provide an engine of adequate power, flexibility, ease of control and ability to operate on any of the fuels obtainable now or later.

IN the cooling system for an automobile engine, the water-jacket must be designed to give ample capacity and free flow of the water. It is essential that water-pump capacities and speeds be figured to equal the radiator capacity so as not to retard the flow of water through the radiator and cause hot water to back up into the cylinder; the radiator must always be kept full and still handle the water as fast as the pump carries it. Fan locations are necessarily considered with relation to the radiator and radiator shroud. Fan diameters, blade path and fan speeds should be given thought, in order that the proper volume of air can be handled to carry heat from the engine. The frontal area of the radiator core in square feet per horsepower developed by the engine and several other details which can be worked out by the fan and radiator manufacturers should receive attention. The best possible fan bearings must be used, giving special attention to radial and thrust loads, fan speeds, etc.