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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.

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.

PROVISION is made, in the piston and rings described by the author, for an adequate flow of heat from all parts of the piston-head to the cylinder-wall by means of adequate cross-section of aluminum alloy in the head and a tongue-and-groove type of piston-ring structure which provides a greater amount of surface than is usual for heat transfer. A labyrinth oil-seal is provided which aids heat transference and prevents leakage past the piston-rings, and the heat transfer is said to be such that the heat does not destroy the oil seal between the piston and the ring. Charts are included that show the effects in reduced temperatures, oil consumption and gas leakage with the construction described. Attention is given also to a skirt construction most suitable to use with the piston-head and rings described.

DETAILS are given of the method of control of the engine so that quantitative and reproducible measurements of detonation and comparisons with spectra can be made. Typical data are tabulated and photographs are shown of the free-burning flames of hydrogen, carbon monoxide, methane, gasoline in a blow-torch, and the like. The spectra of explosion and of detonation in the engine confirm earlier conclusions. By means of a synchronous shutter, the spectra of radiation during the four quarters of a stroke are obtained for straight-run gasoline under detonating and non-detonating conditions for the same fuel containing tetraethyl lead, aniline and iodine as knock suppressers and for cracked-gasoline blends. The outstanding result is that, during detonation, the first-quarter spectrum extends far into the ultra-violet, that of the second quarter, a somewhat less distance; the third and fourth quarters are characterized by very little radiation energy.

NO danger exists of the imminent exhaustion of the petroleum reserves of the United States, as is shown by a committee report published early in 1926 by the American Petroleum Institute, from which figures are given in the following paper. It is reasonable to assume that a sufficient supply of oil will be available for all purposes beyond the time when the demand therefor will be reduced by more efficient use of petroleum products or by the production of substitutes for them. The possibility of a future shortage of petroleum fuel suitable for automotive engines, however, and of the production of substitutes to avoid such a contingency, is receiving considerable attention in America and Europe. The author presents a general review of the situation and the status of research in the manufacture of gasoline substitutes from coal, of which enormous quantities remain unmined in this Country.

CAST iron is purchased on a basis of price instead of quality, according to the author, who says that this has depreciated the qualities of the material generally and caused engineers to look askance at its application. Combined with such factors is the influence of misinformation about cast iron that has been widely broadcast. Questions regarding the design of patterns and cheaper raw-materials have involved the foundrymen in controversial discussion concerning the influence of various elements to the detriment of the economic condition of the iron industry as well as that of the consumer of castings. Due to the lessening of the consumption of cast iron, the foundry world has inaugurated research to better the quality of cast iron, not only through investigations of raw materials but also by improvement in melting practice.

High operating-temperature, the use of the more volatile fuels and a lean air-fuel mixture and the use of lubricating oils of relatively high volatility which contain little carbon-residue all tend to reduce the deposition of carbon in an internal-combustion engine, as indicated by the experimental study reported in this paper. Believing that heat, fuel and oil are the most important factors influencing carbon formation and deposition, the experimenters adopted the method controlling closely the other conditions of operation of a specially designed single-cylinder test-engine and varying the operating temperature and the fuel and oil, allowing the carbon deposit to build up in the normal way during the test periods of 15 and 36-hr. The test engine and control apparatus and the test procedure are described.

Several years ago some of the most prominent leaders in automotive industries cooperated to form a purely engineering group that had as its primary purpose developing a type of rigid-airship construction in which the public would have confidence. It was conceived that such an airship should be (1) Fireproof (2) Weatherproof (3) Durable and permanent in structure (4) Navigable in practically all kinds of weather (5) Economical in the use of buoyant gas and ballast To meet all of these requirements it was decided, after mature consideration, that a substantially all-metal construction was imperative.

Although the generally accepted spheres of usefulness of the airship and the airplane are usually based on their comparative ranges of operation and their speeds, the suitability of either of these types for a given purpose is primarily dependent on two classes of factors, those fundamentally dissimilar and those roughly similar. Conclusions as to relative usefulness should be based on a consideration of the dissimilar characteristics, which include aerodynamic efficiency, size and comfort. Aerodynamic efficiency governs range and, since it determines fuel consumption, influences the cost of operation. The size required depends on the paying loads that are available for carrying. Comfort concerns passenger-carrying only. As the propeller efficiency, rate of fuel consumption and ratio of weight of fuel carried to gross lift are similar in both types of aircraft, the range must depend on the L/D factor, that is, the ratio of gross lift to thrust.

Since the layman and not the engineer buys and drives most of the automobiles produced and because the literature on automobile headlighting presents to[ILLEGIBLE] technical a picture of what happens when the light source of an automobile head-lamp is out of focus, the authors planned and executed an extensive study of the subject in an endeavor to clarify the technicalities by presenting them in the forms of photographs and simple charts, the chief object being to obtain data that emphasize the necessity of accurate control of the size and location of the light source with respect to the focal point of parabolic headlight-reflectors. A great difference in the resultant beam of light is produced by a very small displacement of the light source, either through poorly constructed lamps or due to lack of proper adjustment, and the tests made evaluate how small these displacements and how great these differences are.

After a brief historical review of the development of worm-gears, the author deals with worms and worm-wheels in detail, presenting the subjects of proper choice of materials, tooth-shapes, worm-gear efficiency, the stresses imposed on worm-gearing and worm-gear axles. Usually, he says, the worm is made of case-hardened steel of S.A.E. No. 1020 grade; however, when the worm-diameter is smaller and the stresses are greater, nickel-steels such as S.A.E. Nos. 2315 and 2320 grades are utilized. The worm should be properly heat-treated and carbonized to produce a glass-hard surface. Grinding of the worm-thread is necessary to remove distortions. Bronze is the only material of which the author knows that will enable the worm-wheel to withstand the high stresses imposed by motor-vehicle axles, and three typical bronze alloys are in common use.

The marked advance that has been made in the last 10 years in constructional details and in performance of airplane engines and in airplane performance is reviewed, beginning with the year 1916 when the Curtiss OX-5 eight-cylinder water-cooled engine was brought to its final stage of development. The author describes briefly each type of engine produced successively by the company he represents and tells of the changes that were made to improve the performance. From the 8-cylinder V-type the constructors changed to the 6 and 12-cylinder water-cooled type and are now developing a 9-cylinder air-cooled radial engine that was built in 1925. An important field of usefulness is foreseen for the air-cooled engine.

The effectiveness and the advantages and disadvantages of various substances and compounds that are used or offered in the market for use in the radiators of automotive vehicles as anti-freeze materials are discussed. These include alcohols, glycerine, salts, oils, sugars, and glycols. Properties affecting the suitability of a material or compound, or solutions of them with water to afford protection against freezing at atmospheric temperatures that are likely to be encountered are their heat capacity, freezing-point, boiling-point, specific gravity, viscosity, volatility, solubility, tendency to decompose at the boiling-point, inflammability, corrosive action upon metals, tendency to attack rubber, general availability, and price. The freezing-points of solutions of different materials vary widely at the same concentrations, or proportions to water, and also with variation of their concentration.

As the automobile, a chemical factory on wheels, converts gasoline and air into energy for propelling itself and its load, its prinicpal problems of operation center on the properties and impurities of the raw materials, the utilization and disposition of the by-products and the proper maintenance of the plant equipment. After discussing the nature of gasoline, the author enumerates the five sources from which motor fuel is derived. The major part of the gasoline is said to be obtained directly by distillation from petroleum; about one-quarter of American gasoline, to be secured by the cracking of heavier petroleum oils; about one-tenth, to be gasoline that is separated from natural gas; from 1 to 2 per cent, to consist of benzol and similar material; and fuel used in some sugar-producing localities, to comprise alcohol made from molasses.

Subsequent to an historical review of die-casting, briefly stated, the author covers the subject of present die-casting practices comprehensively and conveys a large amount of specific information. Because many different methods of producing castings exist outside the sand-casting realm, he says that some confusion prevails as to the exact definition of the term “die-casting.” Such castings may be produced in metallic or in non-metallic long-life molds, or in combination with destructible cores. They may be filled by gravity and known as “permanent-mold castings”; or by centrifugal force and known as “centrifugal castings”; or by filling the mold by gravity and, after the outer skin has become chilled, pouring out the excess metal. The last named are known as “slush castings.” On the other hand, a die-casting may be defined as a casting formed in a metallic mold or die, from metal subjected to mechanical or gaseous pressure while in the molten state.

Radiation, although the subject of study for many years, is not yet thoroughly understood. The investigations of von Helmholtz 30 years ago showed that from 10 to 20 per cent of the total heat of combustion is due to radiation; but flames burning in the atmosphere show different characteristics from those subjected to a change of density in a combustion-chamber and the same conclusions do not apply. The possibility of a non-luminous flame's causing loss of heat during and after combustion was first noted by Professor Callendar in 1907. The principal theory as to the source of radiation is that it is due to the vigorous vibration of the gas molecules formed on combustion, and that, like the high-frequency radiations producing light, it is caused by chemical rather than thermal action. It has been shown that radiation emanates almost wholly from the carbon dioxide and the water molecules.

A good air-cleaner is an essential part of automotive engine equipment. Many types of cleaner are on the market and the user must choose on the basis of the three essential requirements of maximum cleaning efficiency, minimum attention from the operator and minimum power-loss. With respect to these three essentials, the development of a laboratory method of testing air-cleaners starts with the premise that the test for efficiency should consist of feeding in a weighed quantity of dust, and an account be made for that which is not separated by the cleaner. The first method was to insert a white outing-flannel cloth in the airstream from the cleaner. The varied degrees of soiling of the cloths from different cleaners were a relative measure of their efficiency. This method was found unsatisfactory for several reasons. An attempt was made to use a dry centrifugal cleaner of predetermined efficiency, in series with the cleaner under test, to catch a portion of the dust escaping.

The importance of the development of a light alloy for use in parts that are subjected to elevated temperatures has already been emphasized in many papers, among which that by S. D. Heron on Air-Cooled Cylinder Design and Development4 should be particularly mentioned. It was with this purpose in view that the foundry of the Engineering Division of the Air Service at McCook Field undertook a brief survey of the alloying, the casting, the heat-treatment, the physical properties and the metallography of an aluminum-copper-nickel-magnesium alloy of the Magnalite type as sand-cast under ordinary foundry conditions. It was found that the alloying involved no particular difficulty. The casting, however, showed the necessity for proper pouring temperatures, gating and placing of the chills and the risers. Several photographs are shown illustrating satisfactory and unsatisfactory methods of molding pistons and air-cooled cylinder-heads.

The term “natural gasoline” has been accepted generally by the petroleum industry as applying to the gasoline product extracted by any process from natural gas. Two processes are in use. The older one is the compression process applied to casinghead gas, which is produced from the oil-bearing sands of oil wells and carries vapors from the oil with which it has been in contact. This process of subjecting the relatively rich gas to a high pressure and then cooling it to or below atmospheric pressure, results in the direct condensation of gasoline which is weathered later to remove the “wild” unusable vapors. The later method is the absorption process in which the gas is brought into contact with a heavy oil, originally of no gasoline-content, which absorbs the gasoline. The enriched oil is then heated to distill off the gasoline, and these two operations of absorption and distillation are repeated continuously within a closed system.