Search Results

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 authors advance for discussion some important problems in the construction of airplanes for military use in this country. The functions of military airplanes designed for strategical and tactical reconnaissance, control of artillery fire and for pursuit are outlined. Problems in construction with reference to the two-propeller system, methods of reducing vibration, application of starting motors, details of the gasoline supply-system, metal construction for airplanes, flexible piping, desirable characteristics of mufflers, shock absorbers, landing gear, fire safety-devices, control of cooling-water temperature, variable camber wings, variable pitch propellers and propeller stresses, are all given consideration. The paper is concluded with suggestions for improvement in design relating to the use of bearing shims, the rigidity of crankcase castings, interchangeability of parts and better detail construction in the oiling, ignition, fuel supply and cooling systems.

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.

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 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 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.

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 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.

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.

Inasmuch as horses cannot meet the demand for increased farm power, the tractor must come at once. So far the supply of tractors has been entirely inadequate to meet the demand. The author specifiies some of the problems that confront designers of farm tractors. To make the tractor immediately available for farm work, it must be adaptable to practically all of the existing types of horse-drawn implements, besides furnishing belt power for a wide variety of present power-driven farm machinery. In designing tractors it must be remembered that the horse is a very flexible unit, capable of a wide variation in power output. Designing a tractor to furnish the necessary power for the majority of farm conditions, requires an intimate knowledge of crops, soils and farm management. These must be analyzed carefully so as to make the machine have as wide a range of usefulness as possible.

The author limits his consideration of rear axles to that of the bevel-gear type and takes up the subject under the heads of load-carrying member, gearing, driving-shaft, brakes and materials. Several different forms of cast and pressed axle housings are briefly described. Mention is then made of the axle gearing and data given showing the end thrust for straight-tooth bevel pinions. The methods of supporting pinions and of attaching bevel gears to the differential are discussed. Forms of differentials are considered, several different conventional types being illustrated. The subject of driving shafts is briefly reviewed, as is also that of brakes and brake materials. The author concludes his paper by figures showing the tensile strength, elastic limit and elongation of the metals used in the various parts of the rear axle and also explains some oil-retaining and dust-protecting features of design.

The authors first define the elementary conditions governing combustion efficiency, dividing these conditions into three main classes. They next compare engines operating on constant volume, constant temperature and constant pressure cycles, dealing specifically with the Otto, Diesel and semi-Diesel types. The main part of the paper is devoted to an outline of the constant pressure cycle, analyzing its advantages as compared with the merits of the constant volume cycle now used in internal-combustion engines. The paper is concluded with a detail description of a proposed constant pressure engine.

Predictable and unpredictable forces will change the direction of the charge-air systems industry. The driver of diesel engine development will be the stringent emissions regulations of the 1990s. The drivers in the gasoline engine market will be improved fuel economy, performance, durability and emissions. Forces will also influence the charge-air marketplace, including changes in emission standards, national fiscal policies, political issues, fuel prices, alternate fuels and consumer tastes. The world community mandate for engines that are clean, quiet, durable and fuel efficient will be satisfied, increasingly, by first-tier component suppliers developing integrated systems solutions.

An inexpensive driving simulation system with sufficient fidelity has been developed. The system produces motion cues of four degrees of freedom, visual and auditory cues, and control feel on the steering wheel. This paper describes the features of this newly developed system and gives examples that demonstrate its effectiveness. The motion cues provided in this system are yaw, heave, and lateral and fore/aft accelerations. The lateral and fore/aft accelerations are simulated by tilting the simulator compartment. A computer-processed road image is given through a CRT monitor. The restoring torque of the steering wheel is produced by an electrical servosystem via a coil spring. Cruising sound is given in order to improve speed perception. Since the system uses digital computers, the vehicle characteristics are altered easily by merely rewriting the software. This enables us to simulate special vehicle dynamics such as front & rear wheel steering.

Many areas of the world are in various stages of development which frequently includes a rapid increase in the motor vehicle population. As a result, some areas are beginning to show the effect of increased motor vehicle use on air pollution. The vehicle's contribution to California's air pollution has long been recognized and studied, and measures have been implemented to reduce emissions from motor vehicles. The history of light duty vehicle emission control in the South Coast Air Basin of California is reviewed. Emission reductions achieved, current levels, projected future emissions and the need for further emissions reductions from light duty vehicles are discussed. For other areas of the world where motor vehicles contribute to air pollution, suggestions are made which can improve the effectiveness of emission control efforts; which should be consistent with political and economic realities, and efforts to achieve international harmonization of standards.