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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

Results of Two Recent Detonation Surveys1

1928-01-01
280006
THE first of the detonation surveys referred to is an extension of the survey of current methods of measuring the anti-detonation qualities of motor fuels; the second is a survey of the relative detonation characteristics of available motor fuels as determined by the routine method of fuel testing now employed at the Bureau of Standards. The survey of methods presented includes a reference to the apparatus and methods described in the 1927 report, and the information regarding laboratories Nos. 1, 2, 6, 8 and 10 is not repeated; but since the other five laboratories, Nos. 3, 4, 5, 7 and 9, use modified apparatus or methods, the paper presents information regarding them as well as similar data for other laboratories. Comparative data on the apparatus and methods described in the paper are presented in a tabulation which includes 20 laboratories. Of these laboratories, at least half rely on the listening method.
Technical Paper

Monoplane or Biplane

1928-01-01
280027
AFTER pointing out that the rivalry between the monoplane and the biplane is of long standing, and that each must therefore have some advantages, the author proceeds to the consideration of the question at issue by comparing structural efficiency, aerodynamic characteristics, performance, and certain other features. In structural efficiency the biplane is considered superior both in strength-weight ratio and in rigidity, but the monoplane has the advantage of being better adapted to metal construction. In aerodynamic characteristics the monoplane has the advantage on the basis of wings of the same area and profile, but the lower lift-drag ratio and greater unit weight of the monoplane wing tend to reduce its superiority. World's records in performance are divided between the two types, and in speed the recent Schneider Cup races show the monoplane and the biplane to be about equal.
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

Single-Engine versus Multi-Engine Airplanes

1928-01-01
280028
MULTI-ENGINE airplanes may be divided into those which can and those which cannot fly with the full normal load after one or more of the engines have stopped. Until within a very short time the former class was practically non-existent. The latter class includes military airplanes in which it is desired to obtain a fuselage having a nose without an engine and those in which sufficient power cannot be obtained from a single powerplant. Some two-engine planes that can fly with a single engine on a test flight fail to do so after having been in use for some time. Ability of a two-engine plane to fly with one engine usually necessitates a sacrifice in the pay-load to such an extent that its operation is uneconomical. Flying with one engine of a multi-engine plane idle is difficult because of the reduction of the propeller speeds of the remaining engine or engines and the turning forces involved.
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

Power Brakes for Passenger-Cars

1928-01-01
280017
THE use of a power medium in brake control points at once to the possibility of simplifying the brake system so that its characteristics, once established, can be expected to remain uniformly effective throughout extended periods without adjusting, with correspondingly long life of brake-linings. The author says also that, if the greater retarding effect possible with mechanically operated four-wheel brakes is to be fully realized, it is necessary to do one of three things: increase the pedal pressure, increase the brake leverage and consequently the pedal movement, or increase the “self-energizing” effect. The vacuum-type brake described is stated to be an amplifier which provides power to supplement muscular strength and assists the driver to apply the service brake, thereby reducing the required pedal stroke and pedal pressure without interfering with the regular service-brake hook-up.
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

Shock- Absorber Characteristics

1928-01-01
280019
AN effort is made to determine the essentials of an ideal shock-absorber and to describe the types that approach or depart from this ideal. Mathematical analysis is not used, but judgment is based on the experience of the author with various types. The requirements of a satisfactory shock-absorber are defined and the methods used by the author in culling out certain shock-absorbers that fail to meet these requirements are outlined. By means of a machine based on the principle, of a steam-engine indicator, the energy required to move a shock-absorber throughout its cycle at varying speeds is measured and charts are obtained. When these charts are compared with a characteristic shape of diagram of a shock-absorber found from repeated trials on the road to give the most satisfactory riding, the merits or shortcomings of any other shock-absorber can be deduced from the difference in shape.
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

Self-Energizing Brakes

1928-01-01
280018
THE theory and characteristics of brakes of the Steeldraulic system are set forth and their application in practice is explained. Self-energizing brakes are said to be desirable because they allow large clearances, low pedal-effort and frictional coefficient and, if properly designed, give a high degree of efficiency with smooth uniform action. To accomplish these results, the controls should deliver equal and accurate actuation to all brakes at all times, be designed to minimize the possibility of becoming inoperative on account of dirt and rust, require no servicing, be noiseless and of good appearance, and remain unaffected by climatic changes. Shoe design should allow very liberal limits and tolerances in wheel, axle and drum assemblies, without causing erratic brake-action or noises. The brake hook-up should follow the simplest line and use the least number of connecting links.
Technical Paper

The Production Engineer's Task

1928-01-01
280020
MASS production and commercial competition have combined to lend great importance to modifications of motor-vehicle design and so have developed new types of engineers known as tool engineers and production engineers, who take the ideals of automotive engineers and convert them into practicalities, so that the design becomes an ideal manufacturing project that makes it possible to produce a car economically. Special tools are required for many of the machining operations, and for the designing of these the more intelligent and skilled of the workmen are developed into tool-makers for the making of fixtures, jigs, dies, gages, cutters, and punches. Gradually the better tool-makers became tool designers and transferred their work from the bench to the drawing-board, becoming twin brothers of the automotive engineer. Of late, the designing and building of special equipment and allied work have entered into the duties of the tool designer.
Technical Paper

Data on Machinability and Wear of Cast Iron

1928-01-01
280022
THE hardness or chemical composition of an iron is, by itself, no indication of the wearing property and machinability of the iron. Irons containing a large amount of free ferrite have been found to wear rapidly, whereas others having considerable pearlite or sorbite in their structure show good wearing properties. The presence in cylinder-blocks of excess-carbide spots or of phosphides of high phosphorus-content is deleterious, because such spots wear in relief and the material ultimately breaks out, acting as an abrasive that scores the surfaces. Causes of wear in cylinder-blocks are discussed, and nickel, or nickel and chromium, intelligently added to the iron is suggested as a means of obtaining the correct microstructure for a combination of good wearing properties and machinability.
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

The Application of Superchargers to Automotive Vehicles

1928-01-01
280040
MOST passenger automobiles are overpowered and probably 80 per cent of such vehicles operate at less than 35 m.p.h. for 90 per cent of the time, according to the author. At 30 m.p.h. an average 3000 to 3500-lb. passenger-car requires from 12 to 15 hp., but the engine carried is capable of developing from 50 to 55 hp. The result is that the car is operated for the greater part of the time at one-third to one-quarter throttle opening. Full power is needed only for accelerating and hill-climbing; during the remainder of the time the excess weight of the engine and other parts must be carried at a loss of efficiency. The author maintains that smaller engines can be used advantageously when equipped with superchargers, the supercharger being used only when excess power is required.
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