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Technical Paper

The Packard X 24-Cylinder 1500-Hp. Water-Cooled Aircraft Engine

1928-01-01
280064
AFTER outlining the history of development of the Packard X engine, the author states the legitimate position in aviation deserved by the water-cooled aviation-engine of this type and predicts large increases in the size, speed and carrying capacity of airplanes within the near future. Passing then to a discussion of the important features of the X-type engine, various illustrations of its parts are commented upon. The cylinders are built-up from steel forgings, with all welds arranged so as to be subjected to no excessive alternating stresses. The novel features of this cylinder design lie in the fact that the valve seats are entirely surrounded by water and that water space is provided above the combustion-chamber and below the top plate of the cylinder. The cylinder-head is extremely rigid, resisting deflection and assuring the maximum integrity of valve seats. The valve ports are machined integrally with the cylinder-head and are not welded thereto as in the Liberty engine.
Technical Paper

Fabrication of the Lockheed Vega Airplane-Fuselage

1928-01-01
280066
THE monocoque type of fuselage construction seems to promise satisfaction of the three requisites of prime importance; namely, high strength-weight ratio, “streamlined” form, and unobstructed interior, according to the author. The conventional method of building a fuselage consists, first, in the construction of a “form” of the required shape, upon which a layer of veneer is fastened. Other layers are applied, and thus a fuselage shell of two or three plies is completed. But the process is expensive and laborious, involving the handling and individual fitting of many small pieces. In the process described by the author, a wooden form of the exact shape of one half of the fuselage body, divided on a vertical plane passing through the center line, is built. This form, or pattern, is next suspended in a large box in which reinforcing bars previously have been woven, and concrete is poured in.
Technical Paper

Lacquer Surfacers

1928-01-01
280025
THE finishing of automotive products with lacquer is still in the transition stage, according to the author. Sufficient time has not elapsed to provide an adequate background of experience which establishes principles and practices that fully meet the requirements of the production engineer. In other words, many of the things we think we know about lacquer finishes and lacquer undercoatings are either not true or are correct in part only. The general function of a surfacer is to provide a smooth surface for the finishing coats. Inasmuch as the larger part of the material applied to provide such a surface must be cut away by sanding so as to bring the surface as a whole to the requisite smoothness, a satisfactory surfacer is one that can be applied with the minimum effort, can be sanded with the minimum amount of labor, and can be purchased cheaply, the reason being that most of it is carried away by the wash water during the sanding process.
Technical Paper

Methods of Building Metal Airplane Structures

1928-01-01
280029
USEFUL load-carrying capacity is a measure of the comparative value of two airplanes of the same size, having identical powerplants, speed, rate of climb and other flying characteristics. It seems to be feasible to combine in the same airplane both the greatest ability to carry useful load and the least cost of construction. Blanked and pressed metal work offers substantial advantage to the extent that parts, particularly sub-assemblies, can be made directly by machine in complete units ready to set in the final assembly. The author shows and describes the methods followed by his organization in forming the members, building the frames and assembling the units of metal aircraft. Trusses are blanked and the web members pressed to ¾-circle form. Dies for long members are variable in length by being made in pieces that can be removed or inserted as desired. Flanged-tube sections are employed for truss chords.
Technical Paper

Duralumin All-Metal Airplane Construction

1928-01-01
280030
PSYCHOLOGY of the public, as well as engineering structure and aerodynamics, is involved in commercial aviation. The public has confidence in metal. With quantity production in view, the author and his associates considered costs of production as related to quantity and also costs of maintenance at airports and in the field, and chose metal as the material of construction. Structural members are fashioned from sheet duralumin rather than from tubes and a type of construction was evolved that can be made with the minimum investment in tools, that is cheap to put together and that can be repaired with the smallest amount of equipment and labor. For compression loads, duralumin has a great deal more strength for a given weight than has steel. It cannot be used, however, for compression members in combination with steel in tension members because of the difference in coefficient of expansion.
Technical Paper

Aluminum-Alloy Pistons in Gasoline and Oil Engines

1928-01-01
280016
COMPROMISES are necessary in designing a piston, sacrificing the quality of least importance under the given conditions. Aluminum alloy is seen as a most desirable material because of its high conductivity and low rate of absorbing heat from hot gases. Aluminum-alloy pistons are now made for oil engines with bores up to 18 in., as well as for small gasoline engines, those described in this paper having their expansion controlled by steel bands embedded in the aluminum but not bonded thereto. Slots cast in the piston allow for linear expansion of the alloy without a corresponding increase in piston diameter and change in cylinder clearance. Advantages of strut-type pistons are shown by thermal diagrams. Illustrations show large pistons and engines in which they are used. Cores and steel inserts for producing such pistons are shown also.
Technical Paper

The Automatic Fabrication of Automobile Frames

1928-01-01
280021
NEARLY all steel used in this process of manufacturing frames comes to the plant in the form of strips, which are rolled to remove curvature and inspected automatically for dimensions. All operations and handling are automatic, except pickling, cleaning and oiling the stock and inspecting the assembled frame, until the enameled frame is ready to be shipped. Economical use of the strip steel is dependent upon an offsetting operation that makes the strip conform to the vertical curves desired in the finished frame. With the aid of illustrations, the author follows the fabricating process through the various lines and other units, until a frame is ready for shipment or storage, within less than 2 hr. after it enters the manufacturing line as strip steel.
Technical Paper

Correlating Test-Data on Heat-Treated Chromium-Vanadium Steels

1928-01-01
280023
AN outline is given of the work performed and the method of procedure followed in correlating test results on specimens of heat-treated S.A.E. chromium-vanadium steel 6130 as a basis for revision of the physical-property charts for certain automotive steels. Revision of the charts was proposed by the Iron and Steel Division of the Standards Committee of the Society, and a subcommittee, of which the author is a member, was appointed to carry on the preliminary work of revision. The paper is a report of the results of the tests made. Test specimens of S.A.E. Steel 6130, to be drawn at three different temperatures after quenching, were prepared by four steel manufacturers. These were distributed among 30 cooperating laboratories, which made a series of about 115 tests including complete chemical analysis, tensile-strength, and Brinell, scleroscope and Rockwell hardness tests on the specimens.
Technical Paper

Alloy Steels and Their Application in the Automotive Industry

1928-01-01
280058
AFTER outlining the progress of research in the development of the alloy steels, the author says that alloys of steel containing nickel, chromium, and nickel and chromium, are the most important to the automotive industry, which is especially interested in alloys containing up to 5.0 per cent of nickel and up to approximately 1.5 per cent of chromium, with the carbon content ranging from 0.10 to 0.50 per cent. The additions of these amounts do not materially change the nature of the metallographic constituents, but the elements exert their influence on the physical properties largely by altering the rate of the structural changes. In straight carbon-steel, especially of large sections, it is not possible by quenching to retard the austenite transformation sufficiently to produce as good physical properties as are desired.
Technical Paper

Progress in Honing-Machines and the Honing Process

1928-01-01
280060
CYLINDER finishing by rough and finish-boring with wide tools, which was thought good enough during the first dozen years of the automobile-production period, was supplanted by reaming and grinding. Later, cast-iron and copper laps were used, but all these methods were slow and did not produce the fine finish for which a demand developed. Experiments were begun about 1920 with the process known as honing. Five years later the company with which the author is connected converted one of its drilling-machines into a single-spindle honing-machine. Other companies made similar conversions. The first honing-head was introduced in 1923. Not until three years ago, however, did honing begin to be regarded as a real production-method possibility. Since then, very rapid progress has been made and numerous improved machines, honing-heads and honing-stones have been produced.
Technical Paper

Designing the Dual Valve-Spring

1928-01-01
280053
BECAUSE of the increased engine-speed and the limitations of progress by the previous method of designing valve-springs, Packard engineers entered upon fundamental studies of valve-spring behavior and of the influence of stress range upon durability. Various theories of the dynamics of valve-spring surge were investigated, and one was found which seems to agree fairly well with the observed phenomena. Jumping of valve push-rods and spring failures that could not be explained by the static analysis of spring design are accounted for by the dynamic analysis, which serves as an improved basis for design. Finding it impossible to design a single spring to meet the conditions, within the space limitations, a double spring with interlaced coils was designed. Descriptions are given of the provision for mounting the ends of the springs and the methods of assembly and inspection.
Technical Paper

The X-Ray Testing of Metals at Watertown Arsenal

1927-01-01
270037
TESTS of metals with X-rays, as made at Watertown Arsenal, are of two classes: (a) radiographic tests in which photographic images of internal details of the gross structure are obtained and (b) diffraction tests in which images are obtained that may be interpreted to give information regarding details of micro-structure of the constituents in the metal. The present paper deals with tests in the first class. Diffraction tests will eventually result in steels that have better physical properties required for special applications in industry, but such improvement must be accompanied by elimination of defects in the gross structure of forgings and castings before the greatest utility of better steels can be realized. Radiographic testing gives pictures of defects whereby the nature of the defects can be determined, but their causes must be sought by logical deductions from other information.
Technical Paper

Commercial Possibilities of Rubber-Electrodeposition Process

1927-01-01
270026
ACTUAL production-equipment for making rubber goods by the anode process has not been installed and studied to yield accurate quantitative data, but laboratory work has been begun in Akron, Ohio, and although some of the facts learned cannot be discussed by the author at this time, enough general indications have been secured to lead to belief that widely varied and valuable applications of the process will be made. Factors that influence the commercial application of any process are enumerated and the properties of rubber that the technologist usually studies to determine its suitability for specific uses are listed. Thorough comparison of anode rubber with the milled product has not been made but confirmatory experimental evidence supports belief that the process must yield stronger and tougher material than do current methods of production. The reasons for this are explained.
Technical Paper

The Electrodeposition of Rubber

1927-01-01
270025
AFTER giving a brief description of the nature of rubber latex and a review of investigations made in Europe of its physico-chemical properties, the author tells of experiments made in Rochester to develop a method for the electrodeposition of rubber particles. These proved that the process was possible but the problem of producing a coating containing all the ingredients requisite in a compound suitable for vulcanizing remained to be solved. The nature of the rubber particles and of rubber after coagulation of the particles is described and the method of rubber-plating as developed is explained. It is stated that the deposit can be built up almost indefinitely and at a very rapid rate; that the composition remains substantially unchanged during coating, and that the current efficiency is remarkably high.
Technical Paper

A Four-Speed Internal-Underdrive Transmission

1927-01-01
270018
ALTHOUGH the enormous demand for automobiles has been met with continual improvement in performance, economy, comfort, and appearance of the vehicle, the development of the transmission has lagged badly for more than a decade. Car-ability has been handicapped by the limitations of the three-ratio gearbox. Notwithstanding that the added car-flexibility, economy and smoothness that result from increasing the number of ratios between the engine and the axle have long been appreciated by engineers, the short-comings of conventional four-speed transmissions, friction drives and two-speed rear-axles having double ring-gears and pinions are many, and the first cost and lack of over-all efficiency of the gasoline-electric drive have prevented their greater use in passenger-car and truck service.
Technical Paper

Chains for Front-End Drives

1927-01-01
270016
TOOTHED and friction-gearing are said by the author to be the two distinct classes of power transmission between two shafts, and the silent chain he describes is in the toothed-gearing class according to his statement, since it has a fixed speed-ratio and causes a bearing pressure that varies almost directly with the power transmitted. It is argued that, because of its elasticity and the peculiar method of contact with the teeth of the sprocket, the silent chain constitutes a medium that absorbs shocks and variations in angular velocity, and has a bearing action similar to that of a belt. The improved silent chain is made of stamped, arch-shaped link-plates assembled in alternate succession and joined by pins that act as bearings. The spacing of the pins forms the “pitch” of the chain. When assembled, the chain can be considered a flexible gear or rack.
Technical Paper

Modern Naval Aircraft

1927-01-01
270072
MORE and more is being demanded of Navy airplanes beyond the requirements of commercial planes. Catapulting and deck landings are required of some planes and corrosion must be guarded against. Bombers and fighting planes each have their special requirements, and planes must be able to land safely on either land or water. The most important developments in aerodynamics now going on are to restrict the travel of the center of pressure of the wings as the angle of attack changes; but widespread adoption of slotted wings and other results of experimental development may be expected. Metal is being used more than formerly in structural work but there are as yet no all-metal service-types in the Navy. Chrome-molybdenum steel is replacing mild carbon-steel in the tubular frames of fuselages, and there is a tendency to seek substitutes for welded joints. Duralumin is slowly replacing steel where welding is not required, but its adoption is retarded because of corrosion.
Technical Paper

The Wright Whirlwind-Engine Production Methods

1927-01-01
270062
REMARKABLE performance of the Wright Whirlwind J-5 engine in the transatlantic and transpacific flights of Lindbergh, Chamberlin, Byrd, Maitland, Smith, Goebel, Jensen and Brock in the summer just closed makes this paper of great timely interest. Methods of manufacture and testing that result in a degree of perfection which enables an engine to function continuously at high speed at almost full load for 40 hr. without the failure of a single part even momentarily must be of prime importance to all internal-combustion-engine production-engineers who hold reliability as an ideal. Extraordinary vigilance at every stage of production of every part is revealed by a reading of the paper to be the major factor contributing to success of the engine. Repeated tests and inspections are made of parts in process and of the engine after it is assembled.
Technical Paper

Integrated Production

1927-01-01
270053
WE are in a new era of production that has been made possible by the broader vision of the production engineer, who is now an established factor in industry because of the demand for reduced production costs. The two factors over which he has control are labor and machinery. Labor cost is of diminishing significance as machinery takes over an increasing proportion of the responsibility for performance. To the two production principles of the division of labor and the transfer of skill to machinery is added a third principle deduced from facts observed in modern production practice. This principle is integrated production, the combining of work units, which are the smallest possible divisions into which operations are broken down by the time-study man, so that a number of identical or similar operations are performed simultaneously by multiple tools, with the maximum efficiency and economy for each tool or each work unit.
Technical Paper

Internal Wheel-Brakes for High-Speed Heavy Vehicles

1927-01-01
270052
The paper deals primarily with internal wheel-brakes for trucks and motorcoaches, but passenger-car brakes with similar characteristics are considered possible. A simple two-shoe internal-expanding type developed mainly by empirical methods is found to be the most practical solution in spite of relatively low circumferential contact. Self-energization is necessary to reduce driver effort with normal pedal-travel. The factors controlling self-energization are explained in detail, and the effect of difference in the coefficient of friction of brake-linings is noted. Distortion of brake-drum and brake-shoes must be limited by a drum of heavy section and by extremely rigid shoes. Rotation of cam with respect to self-energizing shoe should tend to deflect the toe of shoe away from brake-drum surface. A floating cam is necessary to balance unequal wear on the brake-shoes and assure adequate braking with normal pedal-pressure.
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