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FOREWORD Recently, a number of investigators (1), (2), and (3) have reported detection by means of ionization gaps of flame fronts other than those initiated by the spark discharge. Since some of the findings in these studies appeared to be contrary to road-test experience at the General Motors Research Laboratories, the significance of ionization-gap data was questioned. For example, Reference (1) shows abnormal flame fronts occurring in an engine in the absence of combustion chamber deposits, whereas in road testing, it is usually necessary to accumulate deposits before abnormal flame fronts become noticeable. Reference (2) shows data wherein abnormal combustion was unaffected by fuel octane number, while in road testing, objectionable abnormal combustion is usually eliminated by increasing fuel octane number. In order to investigate these apparent anomalies, engine tests were made using special independent ionization gaps.

This paper brings out developments in the application of Automation as we use it in the Automotive Industry, It covers the requirements for Automation, such as alert Management, Proper Machine Tools, Preventive Maintenance, Tool Control, Safety, and the Reallocation of Manpower. Each of these items is presented in general so that the reader will obtain an overall knowledge of the factors involved. It points out those problems which face the manufacturer using Automation and traces the development of an Automation Program. It summarizes the advantages of more efficient use of machine tools, safety, increased production, quality and reduced manual labor for the machine operator and, also some of the disadvantages which have occurred.

A METHOD is described in this paper by which the rates of gear wear under different conditions can be determined by the use of the radioactive tracer technique. With this method one can measure the minutest amount of wear at loads and speeds much below critical destructive conditions. This method makes possible the continuous determination of rates of gear wear at all loads and speeds in actual full-scale units. In this investigation, the radioactive tracer technique has been used to determine the rates of gear wear when using a straight mineral oil and when using an extreme-pressure gear lubricant.

NOISE has two aspects: (1) subjectively, it is any unwanted sound; (2) objectively, it is characterized by many variables. The subjective view is important in determining the response of people to aircraft noise and in establishing engineering design objectives for noise control. The engineering of noise control deals with the objective aspect in three parts: 1. The noise source — characterized by its total noise power output and the distribution of this power with respect to frequency and space. 2. The path — propagation in structures, through the air, and over terrain as influenced by properties of materials, geometry, meteorological conditions, and topography. 3. The received noise — its sound level, frequency spectrum, time pattern, and other variables as required to correlate with the subjective response of man in the aircraft, on the line or in the community.

THIS paper presents a brief historical review of the quest for information concerning the mechanism of aircraft noise generation. It is shown that, after a number of false hypotheses, the noise of propellers was finally traced to the principal aerodynamic loads of the blades. The intensity and characteristics of the noise can now be predicted theoretically from knowledge of the geometry and operating conditions of the propeller. With regard to jet noise, the picture is not so clear. The actual mechanism of noise generation is still somewhat obscure. Included here is a resume of United States and British work on determining the actual source of noise. Experiments on devices for reducing noise are also discussed.

RELATIONSHIP of the factors of lubricant and engine design which affect wear of cams, lifters, rocker arms, and rocker shafts is discussed in this paper, which is part of the Symposium on Cam and Tappet Wear. To reproduce service failures of valve-train parts in the laboratory in a short time, special tests procedures and certain engine modifications were devised for this study. Results of these laboratory tests, which agree well with data obtained in actual service, are presented here.

RECENT improvements in techniques and instrumentation plus further data on rapid chemical chain reactions have made possible a clearer picture of the chemical reactions in engines. This paper describes the present knowledge of the changes in the fuel-air mixture prior to combustion, the effect of these changes on knock, and the method by which antiknocks function. Knock is controlled by the preflame reactions occurring prior to fuel combustion. These reactions are very complex, but the specific reactions causing knock seem to be simple, probably involving very fast reactions initiated by combinations of only hydrogen and oxygen. Hydrocarbon structure affects the rate of accumulation of enough of the hydrogen-oxygen species to cause knock. Tel slows the later stages of reaction, probably by deactivating the hydrogen-oxygen groups. The active antiknock species seem to be either lead oxide or metallic lead.

ECONOMIC conditions in postwar Western Europe are, according to Mr. Pomeroy, responsible for 90% of European cars being smaller, noisier, slightly lighter, but very similar to American cars, and somewhat faster than might be expected. How the designer ingeniously fits the passenger into the seemingly small space afforded by the European car is described in this paper. Other features of European automobiles discussed are their structure and styling.

AN experimental program to determine the influence of crankcase oils on scuffing and pitting of cams and tappets in overhead-valve V-8 engines is described in this paper, which is part of a Symposium on Cam and Tappet Wear. Results indicate that certain additives may eliminate, while others actually promote, scuffing and pitting of a particular type of surface. At the same time, the protection afforded a tappet surface by any particular additive depends upon the tappet material. An additive that protects steel lifters from scuffing may cause chilled iron tappets to pit. In the authors' tests hardenable cast iron was found to be the easiest tappet metal to lubricate. Discussion of this and the other papers in the Symposium starts on p. 220.