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An approach to obtaining laboratory single-cylinder engine fuel octane ratings that agree with car road octane ratings is described. The technique is based on attaining, in the single-cylinder engine, a general duplication of the combustion environment which exists in the multicylinder automotive engine. Because it proved suited to this purpose, a special single-cylinder power section mounted on a CFR crankcase was used. The influence of speed on fuel borderline ratings was in substantial agreement with automotive engine results. Results were obtained on a variety of commercial gasolines and special blends representing extreme variations in hydrocarbon composition. Comparative rating work covered a variety of 1947–1952 and 1955 cars; automotive engine compression ratios ranged from 6.5 to 9.0, and ratios of 10, 11, and 12 were obtained with special engines, heads, and pistons.

This paper was presented at the SAE National Aeronautic Meeting, New York, April 12, 1956. STALL of axial-flow-type compressors limits the flexibility of operation of 1- and 2-spool aircraft turbojet engines. Complete compressor stall or surge is a problem with regard to engine acceleration as well as low-and high-Mach-number flight at high altitudes. Deterioration of compressor performance due to low Reynolds numbers at extreme altitudes aggravates the stall problem. Inlet-flow distortions increase the severity of this problem, particularly for supersonic flight. Rotating stall at low values of equivalent rotative speed is a serious source of blade vibrational failure. This latter problem is also aggravated by inlet-flow distortions.

THE disc-servo brake was designed to eliminate brake fade. To overcome limitations of existing brake structures, desirable features of the disc and shoe brakes were combined. The introduction of three friction surfaces, two pads, and a shoe, and the addition of a ball-and-ramp self-energizing mechanism contribute, the author says, to a brake that has greater fade resistance and longer wear of small segments of the brake lining.

THE selection of transmissions for trucks, with particular emphasis on how they affect the performance of the vehicle, is covered in this paper—the L. Ray Buckendale Lecture for 1956. The author also appraises, briefly, the automatic transmission for truck use. He foresees early progress in this direction for short haul, city, and off-highway units, where shifting and clutch problems are most acute. He expects, however, that it will be some time before they are adopted for highway freight vehicles.

HOLES burned in pistons are usually associated with the word preignition. There are, however, other causes for piston burning, such as, detonation and excessive temperatures, and these as well as the fundamental factors causing preignition, are discussed in this paper. The author suggests that spark-plug condition is probably the most important factor involved in preignition. Considering the other causes of piston burning, operation, maintenance, and possibly fuel variations, all become important because each may contribute to conditions conducive to piston burning.

GENERAL techniques used in the weld repair of magnesium aircraft castings by both gas and arc welding methods are described here. Coverage is given to equipment, methods of surface preparation, preheating, welding procedure, post-heat-treatment. Some typical arc weld repair jobs are described and illustrated. Included also are descriptions of weld defects encountered because of poor welding technique. Typical mechanical property data are shown.

THIS paper describes the background, technology, and recognizes the economies concerning a wider range of fuel quality for the railroad diesel locomotive. Comparisons are made between normal railroad fuel and a wider range of fuel in eight one-year tests in three types of locomotive equipment. The test fuels caused increases in engine deposits, wear, and in contamination of filters and lubricating oil. In five of the tests the test fuels did not interfere with locomotive availability. In three tests changes in materials or methods of maintenance were necessary for continuance of operations. It appears that fuels of the types tested can be used without interfering with locomotive ability if proper precautions are taken.

THIS paper describes the development of a truck automatic transmission, from a statement of broad objectives through the growing pains, to road testing of the final product. Emphasis is placed upon original thinking that led to the decision to undertake such a project, compromises that suggested themselves throughout the various stages, and features tried and found wanting as well as those retained. The finished product is described full though not in detail, stress being placed upon interesting and novel design features.

MATCHING studies of three turboprop engine configurations were made for flight conditions from sea-level static to 600 mph at 40,000 ft. It is concluded that turbine frontal area, stress, and pressure ratio requirements made exhaust-area adjustment desirable. Sfc depended primarily upon flight conditions and turbine temperature, with lowest sfc occurring at highest turbine temperature, flight velocity, and altitude. Free turbines restricted turbine temperature range and produced critical turbine requirements. Increasing a two-spool engine's outer-compressor pressure ratio increased turbine temperature range and made turbine requirements less critical.

A RADIOACTIVE tracer method for measuring connecting-rod bearing wear as it occurs is presented. A bearing wear mechanism is proposed which is substantiated by wear measurements using the above technique. Effects of operating variables and lubricating oils are discussed.

A750-HP aircooled diesel engine has been successfully developed with the primary purpose of reducing the fuel consumption of gasoline-engined-powered combat vehicles by approximately 40%. The new powerplant is characterized by low fuel consumption, light weight, and high compactness. The basic features of the engine are: 5.75-in. bore × 5.75-in. stroke, 1790-cu in. displacement, compression ignition, 4-stroke cycle, direct-injection system, 90-deg Vee, 12-cyl, aircooled, exhaust turbocharged. Rated output is 750 hp at 2400 rpm with a potential output increase up to 850 hp. Engine oil coolers transmission oil coolers, and cooling fans are mounted on the engine and form an integrally cooled powerplant.

TECHNIQUES, based on panel estimates, were developed for evaluating the odor and irritation intensities of undiluted diesel-engine exhaust gases or of various dilutions of these gases in air. Along with the estimates, chemical analyses were made to determine the concentrations of total aldehydes, formaldehyde, and oxides of nitrogen. Statistically significant correlations were found between odor or irritation intensity estimates and the analytical data, but these correlations were too weak to permit accurate prediction of odor or irritation from chemical analyses. Effects of some engine variables on diesel odor were studied. Possible means of reducing diesel odor are discussed.

THIS paper discusses the free-piston engine which is being investigated by Ford. The analytic method for calculating free-piston-gasifier thermodynamic performance over the complete operating range is discussed for the given limitations and conditions. Using these analytical methods, an automotive-size free-piston and matched turbine was designed, built, and tested.

TESTS on two series of diesel engines were run. The first group, consisting of four engines, had the stroke changed only, while the second group had the stroke/bore ratio changed and the displacement held constant. Results of the tests indicate that the longer stroke engines had more power, higher torque, and lower fuel consumption. Friction was high for the short-stroke engines at low speeds and for the longest stroke engine at high speeds. Theoretical analysis indicates that the optimum stroke/bore ratio for best performance may vary as the compression ratio and bore diameter are changed.