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Viewing 15871 to 15900 of 15992
1935-01-01
Technical Paper
350016
Sherman W. Bushnell
1935-01-01
Technical Paper
350049
D. Porter Spencer
1934-01-01
Technical Paper
340066
J. H. Ballard, S. Nixon, N. A. Moore
1934-01-01
Technical Paper
340105
Frank W. Caldwell
THIS paper treats briefly the aerodynamics of the aircraft propeller, including the effect of selection of the airfoil section, the plan form and the aspect ratio. The aerodynamic characteristics of the propeller as a whole are discussed with some reference to the effect of tip speed and body interference. The stress analysis is dealt with, and methods of measuring the vibration stresses are described in some detail. A short analysis is made of the properties and advantages of some of the materials used for propeller blades. An outline of the development of the control-lable-pitch propeller follows, together with a description of the present-type of hydro-controllable propeller now in use throughout the world. In conclusion, the paper deals with methods of testing propellers to assure their safety in service.
1933-01-01
Technical Paper
330035
H. T. Woolson
Mr. Woolson points out that designers are continually trying to make 1 lb. do the work of 2 lb. but are prone to underestimate the important possibilities of alloyed cast iron in automotive engineering. Recent improvements in methods of handling molten metal for casting lends these methods to the obtaining of uniformity of castings and physical properties. Some readily obtainable properties of electric-furnace iron are strength approximately double that of ordinary cast iron, increased wear resistance, reduced growth characteristics, heat resistance and corrosion resistance.
1933-01-01
Technical Paper
330037
W. R. Jennings
Mr. Jennings describes a test now being considered for determining the point of optimum superheat for lifting iron from a static to a dynamic condition, with tensile strength of alloyed cast iron of 80,000 lb. per sq. in. and of heat-treated iron of 100,000 lb. per sq. in. When this field is entered, increased temperature becomes necessary for consistent results, and a series of tests is being run to discover approximately the temperature at which breakdown of the carbon nucleus occurs. The electric furnace, Mr. Jennings asserts, offers a non-oxidizing and non-contaminating method of melting iron at any desired temperature and allows iron to become high-brow and choosy.
1933-01-01
Technical Paper
330065
Hamilton Foley
1933-01-01
Technical Paper
330007
F. F. Kishline
MEASURED gains in performance obtained by using aluminum instead of iron for cylinder head material come from the increased compression ratios possible, Mr. Kishline says, and recommends higher ratios “as a logical means for the engineer to use in creating better transportation.” He gives actual figures taken from observed dynamometer performance showing comparable results on similar engines with aluminum and iron cylinder heads. Desirable features of aluminum heads are presented, after which are discussed design improvements necessary if such heads are to be used successfully. Differences in combustion phenomena resulting from use of iron and aluminum heads also are outlined.
1932-01-01
Technical Paper
320038
F. W. Shipley
INCREASED quality, which is reflected through higher valve-seat hardness and improved microstructure, can be obtained by additions of nickel and chromium to automobile-cylinder iron. Different combinations of these alloys were used, and it was found that a ratio of three parts of nickel to one of chromium gives the greatest improvement in structure in conjunction with maximum hardness. The effect of prolonged heating on three representative plain irons, as well as on three nickel-chromium-alloyed irons of the same base composition, is also shown. A marked difference is revealed in these cases in favor of alloyed irons. A method is given of producing chilled roller wheels by additions of chromium in the ladle instead of using special cupola charges. This is capable of better control and results in a superior product.
1932-01-01
Technical Paper
320037
G. D. Welty
ACHIEVEMENTS of the last ten years in increasing the power-weight ratio of aircraft engines are stated and contributing factors are analyzed. Aluminum alloys have replaced cast iron and steel for certain parts, not entirely because of their lower weight but because of a combination of properties which better fit them for the task. Similar considerations must govern the replacement of aluminum-base alloys by those of magnesium. The most promising immediate field for the magnesium alloys is said to lie in applications wherein strength and lightness are the main considerations and high-temperature properties are of secondary importance. Properties of magnesium castings and forgings are compared with those of castings and forgings of the aluminum alloys. Features of design are discussed which should receive special attention when changing a part from aluminum to magnesium. Machining practices for magnesium are covered in some detail.
1932-01-01
Technical Paper
320057
Thomas H. Wickenden
METALLURGISTS must supply engineers with data on the physical properties of steels so that the skill of both can be used, particularly for machinery in which light weight is essential. The engineer who has not a metallurgical department at his command cannot be sure of duplicating results claimed by steel makers, and the physical-property data that have been given in the S.A.E. HANDBOOK are based on minimum results, for safety. More complete information as to what actually can be expected is desirable, and a subcommittee has had a large number of tests made on identical samples from several heats of two alloy steels. The results for these two steels have been coordinated in probability curves that were developed with the aid of frequency charts. Some steels are not uniform in their physical properties in large sections. The author presents suggestions for steels that are suitable for large sections, with the strengths that can be expected from them.
1932-01-01
Technical Paper
320050
C. L. Humphrey
INSULATING of automobile bodies against noise and heat has been made more complicated by the trend toward lower and more compact bodies and larger and more powerful engines, as more noise and heat are created and must be excluded from the body. Development of the all-steel body also has presented a new problem that calls for different treatment than the composite steel and wood body. Elimination of noise and heat from the body is the mutual problem of the chassis and the body engineers and must be attacked jointly, correction of the trouble being made at the most logical and practical places. Much successful work has been done in the last few years to eliminate noise and heat, but much more can be accomplished by further concentrated effort. After listing the more objectionable chassis noises which have received most attention, the author considers the remaining noise and the heat against which the body must be insulated.
1932-01-01
Technical Paper
320006
F. L. Main
EITHER steel or cast iron will provide a good braking surface provided the grain structure is laminated pearlite, according to the author. Such a structure can be secured in pressed steel by alloying or by case-hardening, in high-carbon steel rings welded to a stamped back and in centrifugally cast iron by careful control without alloying. Uniformity of analysis is important and control of the rate of cooling is still more important in castings. The graphite content of iron is not considered important as a lubricant. Methods of centrifugal casting and of testing are illustrated; also the form and microstructure of representative brake-drums. Discussers agree as to the microstructure needed and present additional views as to ways of securing that structure and the desirability of capacity for absorbing and dissipating heat. They believe grain size and strength more important than hardness.
1932-01-01
Technical Paper
320016
William J. Cumming
Abstract This report of the S.A.E Subcommittee on Motorcoach and Motor-Truck Ventilation states that, to the motor-vehicle operator, ventilation means the elimination of gas odors from the coach body or truck cab; but to the public it means, no doubt, simply proper interior ventilation. Adequate interior ventilation becomes a necessity because of the stigma against buses which has arisen due to their characteristic odor. The investigation of the Subcommittee over millions of miles of operation indicates that there is no one cause of fumes, and certainly no single cure. In the report, discussion is included relating to the causes of gas fumes, such as fumes due to leaks and to engine condition; exhaust-pipe location; carbureter adjustment; the importance of proper driving; engine maintenance and body ventilation. Ten causes of “gassing” are listed.
1931-01-01
Technical Paper
310044
John A. Gann
AFTER reviewing briefly the history of the aluminum and magnesium industries, the author describes foundry practice in the production of magnesium and magnesium-alloy castings, their heat-treatment and the effect of various fabrication processes on the microstructure and physical properties. The general classes of commercial magnesium-base alloys now in use in this Country are discussed at some length with particular reference to the combination of extreme lightness with good physical and mechanical properties that is obtained. Applications of magnesium alloys in the aircraft and automobile industries are outlined in a section of the paper. Many of these are illustrated. In conclusion the author states that the importance of magnesium as a structural metal is now being recognized, especially as the factors that have retarded its development and restricted its use are overcome.
1931-01-01
Technical Paper
310043
Robert M. Curts
THE PURPOSE of the paper is to discuss zinc as an engineering material. To this end the author reviews briefly the part that zinc and its alloys have played in the past and discusses recent development in zinc-base alloys which have greatly enlarged their field of use in the automotive industry. Among the various specific subjects treated by the author are brass, nickel and silver, rolled zinc and rolled zinc-alloys, zinc wire, extruded zinc shapes and die-castings. He states that in the early days of die-casting, alloys composed principally of tin or lead were used almost exclusively, but that castings made of these alloys did not possess the necessary strength and their use was greatly restricted. Zinc was tried and found to have certain advantages and, finally, a special zinc-alloy was adopted. Shortly after this the so-called high-grade zinc was introduced.
1931-01-01
Technical Paper
310016
R. T. Haslam, W. C. Bauer
AFTER briefly describing the hydrogenation process and its three characteristic reactions, purification, stabilization and homogenizing, that remain unaltered in direction although they all change in extent, the authors discuss the possibilities of applying the process to the production of motor-fuel and lubricating oil. The possibilities offered by the process of reforming the molecular structure of petroleum hydrocarbons along directed lines to obtain products of the so-called paraffinic or naphthenic type are stressed. This presentation is supplemented by data on the actual properties and performance characteristics of hydrogenated gasolines and lubricating oils as tested by the fuel and lubrication laboratories of the Standard Oil Development Co. Two series of tests were run, one on a White motor-truck engine and the other on a Mack motor-truck engine, the latter being under abnormally severe conditions.
1931-01-01
Technical Paper
310008
Edward M. Getzoff
MORE THAN SEVEN YEARS of investigation of the problem of preventing valve-seat erosion under severe operating conditions in motor-truck and motorcoach engines are reviewed briefly. Engineers are said now to be generally agreed that an insert of some non-ferrous material is the only means of obtaining a valve seat that will stand severe service. A theory for the cause of a thin spotty deposit or pick-up on the valve seat that accelerates erosion is advanced, and this deposit is said to be absent on valve seats made of non-ferrous metals. Aluminum bronze gives satisfactory results but is difficult to secure to cast-iron cylinder-blocks because of its greater coefficient of expansion. Several partially successful methods of securing aluminum-bronze rings to cast iron are shown. A method that is applicable to one alloy which has reduced erosion under the most severe operating condition to such an extent that it is almost negligible is described.
1930-01-01
Technical Paper
300024
S. D. Heron
FUELS for use in aircraft engines are discussed with reference to their antiknock value, volatility, vapor-locking and engine-starting properties, gum content and availability, and to antiknock agents. The usefulness of a fuel for spark-ignition engines is stated to be limited by its tendency to heat the cylinder and the piston unit. Definite evidence is available that the tendency of fuels to heat the cylinder unit is not always in accord with their tendency to cause audible knocking. The fuel required depends upon the compression ratio of the engine, its volumetric efficiency, the design, size and temperature of the cylinder unit, and the rate of revolution. Mid-Continent Domestic Aviation gasoline having an approximate antiknock value of 50 octane-50 heptane gives excellent results if the engine output is kept within the limitations of this fuel but is not suitable for many modern aircraft engines if flown wide open at sea level.
1930-01-01
Technical Paper
300010
FRANK JARDINE
1930-01-01
Technical Paper
300003
F. A. Moss
This is the fourth report by Dr. Moss on the investigation of riding comfort at the George Washington University and is a progress report on the measurement of automobile riding-qualities. The previous reports were published in the S.A.E. JOURNAL as follows: September, 1929, p. 298; January, 1930, p. 99; and April, 1930, p. 513. In this report, which was presented at the 1930 Semi-Annual Meeting, the author describes improvements made in two wabblemeters for measuring physiological fatigue caused by riding and the use of two accelerometers to correlate the behavior of the automobile with the physiological results. Results obtained with two groups of subjects, one consisting of taxicab drivers and the other of university students, are summarized, and the results of preliminary tests of the comparative riding-qualities of different cars as shown by their effects on the subjects are also given.
1930-01-01
Technical Paper
300002
F. A. Moss
EXPERIMENTS that have been in progress since the 1929 Semi-Annual Meeting to measure the fatigue caused by an automobile ride, using the human body as a measuring instrument, and to predict there-from the possible effects of various types of spring-suspension, shock-absorber and other comfort-giving components are described. Initially, the problem was approached from the physiological standpoint because fatigue is definitely known to be a physiological phenomenon and, if the physiological changes are sufficiently marked to be measured, physiological tests are definite and quantitative. Changes in the human body are a good index of relative comfort, and, if the normal reactions of an individual or any group of individuals before a test are known, similar measurements at the end of a test or at the end of an automobile ride should show an appreciable difference.
1930-01-01
Technical Paper
300040
R. L. Templin
COMPARATIVELY large rake and clear angles required for best results leave a relatively thin cutting-edge on a cutting tool for aluminum. One difficulty encountered is that tools of such form are not always available or suitable, for various reasons, for instance, small tools of various types are available only with cutting edges suitable for steel and bronze, and the desirable amount of top rake cannot well be provided on circular form-tools. Tool bits of various sorts can be reground to the desired angle. A simple round form of tip that is shown can be utilized in tools for various purposes, including use as inserted teeth in a face-milling cutter. High-speed-steel tools are suitable for most aluminum alloys, but alloys containing a high percentage of silicon can be machined to advantage only by using cemented tungsten-carbide. Machine-tools should be suitable for high speed.
1929-01-01
Technical Paper
290045
R. H. SOULIS
FIRST reviewing briefly the history of molded brake-lining, the author states that the introduction of molded lining has, until recently, met with considerable opposition. After the first volume-production adoption in 1924, there were no further adoptions of the strictly molded types in production until 1927, when the trend in brake design seemed to change suddenly from the external type to the internal type of brake. The present movement toward the use of molded brake-lining was brought about through the inability of woven lining to meet the exacting demands of some of the newer types of internal brake. In the author's opinion, the molded type of lining has more nearly fulfilled the present requirement of internal brakes than has any other type. He states that at least seven different brands of molded lining are now on the market, and that three of them are in large-volume production.
1929-01-01
Technical Paper
290040
E. R. LEDERER, F. R. STALEY
SELECTION of the proper crude is an important consideration in the manufacture of aviation-engine oils. The authors class petroleum into asphalt-base, paraffin-base and mixed-base crudes, stating that scientific research and actual-performance tests have demonstrated the advantages of paraffin-base oils over asphalt-base oils for aviation engines, and that their superiority is now conceded by most authorities. Much attention has been given recently to the dewaxing and fractionating of lubricating oils, and this has resulted in an improvement in their quality and in their unrestricted use as “all-weather aero oils.” After quoting statements from several authorities who agree that an oil which will meet both summer and winter requirements is desirable, the authors give the definitions of viscosity, fluidity, consistency and plasticity determined by the American Society for Testing Materials and then discuss the fluidity or consistency of aviation-engine oils below their A. S. T.
1929-01-01
Technical Paper
290043
A. B. Cox
1929-01-01
Technical Paper
290003
FRED AUGUST MOSS
THIS IS a preliminary report of the results obtained to date in the study of fatigue incident to motor travel, which is part of the Society's Riding-Qualities Research program. A series of physiological tests were conducted after muscular fatigue had been induced by a known amount of work, with the hope of finding some tests sufficiently sensitive to measure less pronounced types of fatigue. These fatigue tests conducted on subjects after riding showed that a decrease in the carbon-dioxide combining power of the blood and an increase in metabolism are fairly satisfactory indications of muscular fatigue, but the results led to the conclusion that the fatigue which accompanies riding in automobiles does not represent a very marked muscular fatigue, and suggested that it may represent a condition more closely similar to nerve fatigue. Consequently, a rather extensive study of various tests of nerve fatigue was undertaken.
1929-01-01
Technical Paper
290066
L. B. RICHARDSON
AT first believed immune, aluminum alloys have been found extremely susceptible to both surface corrosion and intercrystalline corrosion. The latter goes on under paint that has been applied to imperfectly cleaned surfaces, and shows only as blisters. Because of this, it has become commonplace to break with the fingers the ribs and the trailing edges of duralumin lower wings and tail-surfaces. Contact of duralumin with brass or steel hastens corrosion, and protective paint coverings are dissolved by dope where fabric surfaces meet metal parts. All-duralumin structures are not considered suitable for sea-going aircraft unless all joints and seams are of water-tight construction, not only in hulls but in other members of the structure. Corrosion over the land is much less severe. Few manufacturers seem awake to the importance of corrosion. The fight to avoid it should begin with avoiding seams that are difficult to protect and hollow members that cannot be sealed hermetically.
Viewing 15871 to 15900 of 15992