Search Results

THE track-laying type of vehicle is, of course, old. The emergency which brought the modern “tank” into existence was the menace of the machine-gun. The tank is simply a device that can approach closely and destroy the gun or its crew. It is fundamentally a man killer, and its strongest points are speed and mobility. It is now an indispensable arm of the military service. The writer gives a rapid résumé of the fantastic period in design, the early work done on heavy armored cars and the reasons for concentrating on the track-laying type of vehicle. The American type of track was adopted as a foundation and from this and around it France, England and the United States have developed the tanks known through successful use in the war. The British are to be credited with producing the first practical fighting machine of this type. France has two types of machine, one mechanically driven and the other with electric drive, both small.

THE production of gasoline in this country could be increased through the following changes in refinery practice: (1) Universal adoption of a high “end-point,” or upper volatility limit for gasoline (2) General use of more efficient distillation methods and equipment (3) Recovery of gasoline now lost in refinery operation (4) Wider use of cracking processes Other possible methods of increase are not considered of sufficient importance to merit discussion in this connection. Some of the details of the four methods of increase are discussed and it is estimated on the basis of the evidence now at hand that the maximum percentage increases in production under the four heads listed are as follows: (1) 15 to 20 per cent; (2) 10 per cent; (3) 10 per cent, and (4) 100 per cent.

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.

The author states as his object a review of what has been done and what must be done to make tractors successful in operating on low-grade fuels, especially kerosene. He takes up in order the four principal methods in common use of applying heat to vaporize kerosene, pointing out the advantages and disadvantages of each method and of its modifications. The author then cites various experiments with different types of carbureters in burning kerosene, drawing at length upon his own experience in this connection. He cites difficulties with gas distribution, manifold condensation, pistons and spark-plugs and points out that carbureter design is inseparable from considerations of tractor engine and manifold design. That better progress has not been made in the past in developing kerosene-burning tractor engines is stated to be largely owing to the fact that there has not been sufficient cooperation between engine and carbureter manufacturers.

After noting that the early development of the automobile industry took place at a time when gasoline was a drug on the market, this paper reviews the cycle of operations of a standard gasoline engine in order to point out its limitations and the possibilities of utilizing a less volatile fuel than gasoline and of securing lower consumptions of fuels of all kinds. Compression and expansion limitations and the reduction of mean effective pressures at light loads are considered. Disadvantages of throttling control are pointed out, citing as a parallel example the trend of steam engine design away from this means of control. The author then outlines the advantageous features of the improved Diesel engine design, and by means of curves shows the great fuel economy of this type as compared with gasoline engines. He concludes by defining “the ideal tractor engine.”

The author calls attention to the unreliability of the magnetic compass when used for aerial navigation and to the possible development of the gyroscopic compass for this purpose. He then explains how the drift of an airplane in flight makes it difficult to follow with accuracy a given course devoid of landmarks, unless an accurate drift indicator using the principle of the stroboscope is available. The development of such an instrument is then described, as are also means for synchronizing it with the compass. The use of the automatic synchronized instrument in flight over land is outlined, and its application to flight over water is described in considerable detail. Rules for aerial navigation over water, observation as to movement of wave crest and determination of wind velocity and direction are considered in their relation to the use of the instrument.

The authors outline some of the problems that confront the automobile engineer today, showing how the demand for better performance and economy and the ever-increasing cost of volatile fuels has emphasized the necessity for thorough engineering work in the successful automobile manufacturing plant. Believing that the accurate analysis of the heat distribution in a modern automobile engine will be of great value, the authors describe a comprehensive test, made under their direction, of such an engine. This test includes measurements of the brake horsepower, friction horsepower, fuel consumption and heat losses to jackets, exhaust and cooling air. The engine tested was inclosed in a hood, similar to that used on the car in normal service and an air blast was directed through this hood at speeds approximating those at which the engine would drive a car with a given gear ratio.

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.

The author believes that an incompatibility exists between the results achieved in this country by the growth of the automobile industry and the almost complete lack of rational data on the most essential elements of kinetics relating to the modern automobile. He submits considerations that can be used in establishing a rational theory of spring suspension in general. A few words are devoted to the first principles of dynamics of springs, to damping, kinematic features of harmonic motion, energy consumption and shock absorbers. An introductory problem, involving an imaginary one-wheel “elemental car”, meant for purely inductive purposes, is then analyzed. Finally the main problem is presented in the form of an analysis of a skeleton-car, spring-suspended and simplified as much as possible.

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.

This paper discusses the principles of battery ignition and then describes high-tension magneto ignition. A comparison between the two types of ignition is given, and the paper concludes by illustrating diagrammatically how and why a very hot spark causes the engine to produce more power and to economize on fuel consumption.

After a few general introductory remarks the author outlines the operating requirements for tractors, and takes up the matter of the proper sizes of tractors, stated in horsepowers per given number of plows. The use of lower-grade fuels, value of water in the engine, cylinder construction, methods of lubrication and design of drive-wheels are the subjects covered by the balance of the paper.

The author first compares mineral oils with certain other liquids in order to point out clearly certain of their characteristics. He then shows the economic benefits that would result from making more of the crude available for use as fuels. He discusses such topics as cracking methods in use, advantages of dry gas, initial flame propagation, gas producers, hot mixtures, wet mixtures and difficulties of correcting existing engines. He concludes by proposing as a solution of the gasoline problem the more general use of superheated homogeneous fixed dry gases made in vaporizing devices independent of engine cylinders, and outlines means for attaining this end. Performance data covering the use of mixtures of kerosene and gasoline on several cars are included in a table, and several charts throughout the paper illustrate many of the topics discussed.

The author states that the objects of the paper are to define and trace the development of the various processes of carburetion, and to offer such suggestions along these lines as may assist the investigator in developing motorboats, automobiles and self-contained unit motor cars for railway purposes. The surface carburetor is mentioned chiefly as of historic interest. In considering the jet carbureter the author discusses the proportion of gas desired, the effect of the varying inertia of the air and the liquid gasoline and the breaking up of the combustible needed. Following sections review the devices for using kerosene, such as gasoline jet carbureters to which heat is applied, devices of the fixed gas type, the introduction of combustible directly into the cylinder, forcing combustible directly upon a hot surface in the cylinder and devices which raise the combustible to the boiling point.

The author states that the purpose of the paper is to outline that phase of metallurgical work pertaining to the connection between the laboratory and production in the automotive industry. Reasons are cited for selecting certain designs for parts to facilitate machining, complete or partial case-hardening, finishing and assembling. The next step is the choice of materials, a subject which is treated at some length. The author then takes up in turn the field for standardization in steel specifications, inspection of materials, physical testing of steels, uniformity of composition of metals, heat-treating operations, methods of carburizing, depths of case-hardening, treatment after carburization, errors in overspeeding hardening operations and drawing heat-treatment at low temperatures. Types of pyrometers, operations on hardened work, inspection for hardness and selection of hardening equipment are some of the other topics discussed.

This paper emphasizes the importance of using standardized testing equipment in order that mental calculations may be avoided in interpreting the reports of other engineers. The situation and environments of the engine-testing plant, cooperation among the men conducting tests, standardized methods of conducting tests, value of venturi meters and testing of accessories are among the subjects discussed in the first part of the paper. The subject of the testing of engine cooling systems is treated at some length, the importance of obtaining operating conditions being emphasized. The paper concludes with two sections covering spark-plug testing and tests for preignition.

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.