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RESULTS of an investigation into the effect of shot-peening variables and the resulting residual stresses on fatigue life are reported in this paper. Leaf springs were the simple specimens heat-treated, cold worked, and tested in this study. Some of the conclusions reached are: 1. There is a minimum shot velocity for each shot size to obtain best fatigue life, and this value is much lower than that normally used. 2. Exposure time for this type of shot-peened specimen beyond some minimum value is wasteful and costly. 3. Shot size has little influence on fatigue life for these specimens. 4. Shot peening specimens while under tensile strain greatly increases fatigue life at 200,000 psi nominal stress over that of nonpeened or strain-free-peened specimens. 5. Shot peening these specimens gave residual compressive stresses 50% of yield strength, and these stresses can be increased to more than 50% by strain peening. 6.

THE design and construction of the PowerFlite automatic transmission are described by the authors. It is of the torque converter type, some models being water-cooled, while others are direct air cooled. Details of the hydraulic controls are explained, including the one-piece shift valve and the shuttle valve for controlling closed-throttle shifts. It is claimed that this transmission has relative simplicity, light weight, and smoothness of operation.

THIS paper presents flame temperature and pressure data taken on a spark-ignited CFR engine. Data are presented for the four variables of cyclic reproducibility, knock, air/fuel ratio, and ignition timing. The data indicate that cycle-to-cycle irreproducibility may be caused by variations in the initial rate of flame propagation from the spark.

THIS paper discusses a method of measuring compression temperature by means of the absorption of light. An optical-electronic system measures the change in color of a trace of iodine gas that has been added to the intake mixture. From these measurements the temperature of the iodine and by inference, the temperature of the gases, is determined. The apparatus used is described briefly and the test results obtained in measuring compression and end-gas temperatures in a spark-ignition engine are also presented.

THE indicated output of a 2-stroke engine is primarily dependent upon the success with which the products of combustion are driven from the cylinder and are replaced by fresh air or mixture during the scavenging period. Such replacement must, of course, be accomplished with a minimum of blower power. This paper deals with various aspects of 2-stroke research conducted at M.I.T. during the past 10 years. Among the subjects discussed are the methods used in the prediction and measurement of scavenging efficiency, and the effect of engine design and operating variables on the scavenging blower requirements as reflected by the scavenging ratio.

A DETAILED analysis of the weight-saving possibilities of shaft-turbine installations on helicopters is presented in this paper, which won the 1953 Wright Brothers Medal for its authors. They point out that this weight saving helps to counteract the disadvantage of high fuel consumption. They also discuss helicopter flight characteristics and how they are related to shaft-turbine power characteristics. Finally, they propose some methods of obtaining better matching characteristics between helicopters and shaft-turbines.

THE history of the free-piston and turbine compound engine development is reviewed briefly. After consideration of the status here and abroad, the salient features of the free-piston engine concept are considered. These are mechanical simplicity, compactness, and an excellent torque-speed characteristic, coupled with a fuel economy comparable to the conventional diesel, the modern record holder in this respect. Some prognostications for the future of the development in this country are also presented.

EXPERIMENTAL analyses of residual stresses as related to fatigue properties and to the surface failure known as spalling are discussed in this paper. How those processing operations such as heat-treatment, machining, grinding and straightening contribute the factors causing residual stresses and what are the practical methods of measuring these stresses are also described here.

SOME of the aerodynamic and mechanical problems of jet engines designed for supersonic flight speeds are discussed in this paper. The aerodynamic problems considered include the required range of operation of the compressor, the thermal efficiency of the cycle, the inlet-engine airflow match, and jet nozzle design. Structural difficulties due to high operating pressures and temperatures and the bearing and lube problems arising from high temperatures are also presented.

THE truck engine of the future will be capable of producing more horsepower and will operate at higher rpm, according to Mr. Michell. This means, he said, that new problems will arise in connection with the clutch, transmission, propeller shaft, and rear-axle design. The author discusses some of these problems as far as each of the above parts of the drive line is concerned.

WHY one gets that aching neck and those tired eyes after driving for long stretches is explained in this paper. A brief qualitative study of the motion of the driver and passenger in the front seat of an automobile is given here. The author provides a reasonable explanation for some of the commonly observed kinds of driver fatigue and points the way for some improvement in the dynamic comfort of automobile seats.

MANY rather intriguing claims have been made about reduction of engine friction and increase of power and fuel economy through the use of certain types of motor oils and motor-oil additives. However, this paper shows that engine fuel-consumption measurements to determine the effects of different oils and oil treatments indicate that the only significant property of the engine lubricant relating to engine power, friction, and fuel economy is viscosity. The data also indicate that the “engine viscosities” of some motor oils may be somewhat different from their “laboratory viscosities” as measured in conventional Saybolt or Kinematic viscosimeters.

FATIGUE failure is now one of the most serious hindrances to satisfactory service life for helicopters. To help the industry bring the fatigue failure problem under control, these authors summarize what they have learned from studying 169 fatigue failures that occurred during 58,000 hr of helicopter flying operations. They have classified these failures as being caused by: 1. Design error. 2. Manufacturing error. 3. Field error. They discuss specific examples in each group and what was done to correct the cause of the failure.

SEVERAL factors are involved in the answer to the question, “How do atmospheric conditions affect the ability of a fuel to satisfy the antiknock requirement of automotive engines?” As is well known, an increase in atmospheric temperature increases the octane-number requirement of engines. This paper points out, however, that this causes little change in the road octane-number ratings of commercial fuels. Increasing the absolute humidity has the opposite effect to increasing the temperature and tends to counteract the undesirable effects of changing temperature throughout the various seasons of the year. Increasing the barometric pressure or decreasing the wind velocity both increase the tendency of commercial fuels to knock. Factors indirectly related to weather conditions, such as the coolant or thermostat used in an engine, also affect the knocking tendency of a fuel.

THE new Packard automotive diesel engine is reported to feature reductions in weight and space occupied, while maintaining good life expectancy. It is available in 6-cyl in-line, V8, V12, and V16 models. These models all have a large number of interchangeable parts. They all have the same bore and stroke. According to the authors, noteworthy points of these engines include: 1. Extensive use of aluminum. 2. Turbosupercharging. 3. One-piece cylinder and head assembly. 4. Four valves per cylinder, with stellite seating surfaces on valves and seats in the head.

THE universal positioning seat track is said to be the answer to the problem of providing suitable automotive seating for practically all drivers. It allows each driver to adjust the car seat to the position that best satisfies him. The author points out that providing these adjustments gives a number of advantages, such as: 1. The visibility of the driver can be at a maximum. 2. Each driver of a car can adjust the seat to suit his own individual size-and taste. 3. Less driver fatigue.

HIGHWAY safety-an important problem in the truck and bus industries - is governed by many factors, one of the most important being the human element. This paper describes the Harvard School of Public Health research program concerning the human factor in vehicle design and operation. The project is Sponsored by the Commission on Accidental Trauma of the Armed Forces Epidemiological Board, Department of Defense; the National Association of Automotive Mutual Insurance Companies; the American Trucking Associations, Inc.; and the National Association of Motor Bus Operators. Some items of this investigation include the study of near accidents; detection of the accident repeater; personal adjustment and morale of drivers; human body size and capabilities with relation to controls, instruments, seats, and vision; the effects of temperature, ventilation, noise, and vibration; and desirable safety features to protect the operator if an accident occurs.

STRESS corrosion cracking is a combination of stress and corrosive action that results in individual cracks of a brittle, intergranular nature. The author discusses such failures in compressor rotor blades made of a 12% Cr, type 403 stainless steel. A laboratory technique was worked out for producing similar failures at will. As a result of this study, it was recommended that compressor blades be stress relieved at 950 F. Since this has been done, no further cracking of the blades has been reported. Tests with three alloys in addition to the type 403 showed the former alloys to be superior to 403 in regard to stress corrosion cracking.

RESULTS of the two largest cooperative surveys made in 1951 and 1952 of the antiknock requirements of passenger cars are presented in this paper. Conducted under the auspices of the Coordinating Research Council, data on more than 800 postwar cars are compared with previous surveys and are analyzed for relationship of car design, car age, engine speed, test conditions, test fuel type, make of transmission, and geographical car distribution to octane-number requirements.