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Viewing 43681 to 43710 of 44126
1934-01-01
Technical Paper
340031
Martin Schreiber
1934-01-01
Technical Paper
340086
E. S. Hall
1934-01-01
Technical Paper
340087
J. B. Fisher
1934-01-01
Technical Paper
340088
Alex Taub
VIBRATION formerly was classed as such without much thought as to the determination of its sources, Mr. Taub states, and then came isolation of the various causes. The first two vibrations to be segregated and vigorously attacked were the secondary inertias of reciprocating units and torsional vibration. The development of the six-cylinder engine was among the earliest attempts to eliminate secondaries, and it was also the earliest producer of torsional vibration. Dynamics, combustion roughness, torsional roughness and structural weakness, are a few of the contributing causes of engine roughness. Consideration must be given to all these factors if an engine is to be considered inherently smooth, and each is analyzed. Engine mountings should have low resistance to rotation about the longitudinal principal axis and to rotation about the vertical axis through the center of gravity, together with minimum shift of affective principal axis and vertical axis.
1934-01-01
Technical Paper
340083
A. Coppens
A “COMPLEMENTARY” term should be added to the usual formula for computing the counterweights of single-row and double-row radial engines, and the complete corresponding formulae are given in the paper under numbers (6), (7), (16), (17), (6′), (7′), (16′), (17′). The compared effect on engine balance of “complete” and “incomplete” formulas for said counterweight is discussed, with actual figures, in the paper.
1934-01-01
Technical Paper
340084
E. G. Gunn
1934-01-01
Technical Paper
340074
Kurt Schnauffer
DR. SCHNAUFFER presents in this paper the results of research on and measurements of combustion processes in internal-combustion engines by means of a slow-motion camera and a micro-chronometer. This method for flame-propagation indication depends on the physical property of flame to ionize air gaps and hence make them conductors of electric current. The recording equipment used is very simple, he says, and can be simplified still further if only visual inspection of the combustion processes is desired. He gives also a brief review of the history of combustion-process research, and a bibliography. Using this method, all the conditions affecting the speed of flame-propagation in a high-speed spark-ignition engine were examined, and Dr. Schnauffer emphasizes that the results were accurate. Neon lamps can be substituted for an oscillograph, if desired, and are less expensive; further, this makes possible the registration of an unlimited number of test points.
1934-01-01
Technical Paper
340068
P. J. Sampson
1934-01-01
Technical Paper
340067
Fred R. Nohavec
1934-01-01
Technical Paper
340066
J. H. Ballard, S. Nixon, N. A. Moore
1934-01-01
Technical Paper
340063
Guy L. Tinkham
1934-01-01
Technical Paper
340117
Torbjorn Dillstrom
THERE has, for many years, been a demand for an automotive engine more economical in operation than the gasoline engine. As the Diesel engine had early established a good reputation for economy, the development work on a more economical automotive engine quite naturally centered around this type of engine. Additional advantages can, however, be gained by combining fuel injection with spark ignition, and an engine of this type has been developed by K. J. E. Hesselman of Stockholm, Sweden. This engine is generally called the Hesselman engine. In the spark-ignition fuel-injection engine the charge is formed at a certain time before the spark occurs, and this makes it possible to mix fuel and air thoroughly whereby high output is secured. Engines operating on fuel oil with a compression ratio of 7.5 : 1 have given a brake mean effective pressure of over 125 lb. per. sq. in.
1934-01-01
Technical Paper
340118
Thomas C. Van Degrift, John M. Tyler
THE authors state that the balance of a machine part or group of machine parts is a function of the motion of their center of gravity, and that perfect balance of the moving parts exists when their center of gravity remains stationary. When the center of gravity oscillates, unbalance is present, the amount being proportional to the magnitude of the oscillation of the center of gravity. The subject of balancing is discussed practically, balancing machines being also described and commented upon. The seven main requirements of a good balancing machine are stated. Regarding balance limits, in computing those for an assembled engine, the first item is to obtain the balance on each of the rotating parts and the second, to ascertain the limit to be placed on the fits of “pilots.” In conclusion, fourteen items constituting the total unbalance of the engine chosen for illustration are enumerated.
1934-01-01
Technical Paper
340116
H. H. Allen, G. C. Rodgers, D. C. Brooks
ICE formation in the carburetor must depend on, at least, the factors (a) volatility and heat of vaporization of the fuel; (b) mixture ratio; (c) humidity, pressure, and the temperature of the intake air; and (d) heat transfer between the carburetor and its surroundings, especially the engine, according to the authors. Small-scale and full-scale tests were made, descriptions of the seven fuels used and of the testing apparatus being given. The procedures for both sets of tests are outlined and the results are analyzed. Other subjects treated are the heat necessary to melt ice, and correlation with the A.S.T.M. distillation. Five conclusions are stated. Appendix 1 refers to calculation of the relation between intake and mixture temperatures when ice formation occurs. Appendix 2 treats of the construction of equilibrium-air-distillation curves for a series of supplied mixture ratios. Appendix 3 is concerned with engine operation near the danger zone and definition of border conditions.
1934-01-01
Technical Paper
340111
A. W. Pope
EIGHT different models of the Hesselman engine, ranging in bore from 3¾ to 6½ in. and in power from 25 to 170 hp., have been developed and produced since the first production engine was completed about two years ago, according to Mr. Pope, and hence it has passed the experimental stage. It is a low-compression engine that burns Diesel fuels. Mr. Pope states that one of these production industrial engines has developed a mean effective pressure of 104 lb. per sq. in. and that a full-load economy of 0.58 lb. per b.hp-hr. has been obtained. Further, that its economy lies about half way between that of a carburetor engine and a Diesel engine. The operation of the engine is described, suitable fuels for it are discussed, and data resulting from tests are presented. In conclusion, Mr. Pope states that the engine has provided a means for handling heavy fuels at low compressions.
1934-01-01
Technical Paper
340109
Carlton Kemper
THE National Advisory Committee for Aeronautics has undertaken a research to determine the effect of the fundamental factors influencing the cooling of air-cooled radial engines. This paper presents some of the results of an investigation made to obtain information that can be used in the design of fins for the cooling of heated cylindrical surfaces in an airstream. An equation has been developed for calculating the quantity of heat dissipated by a given fin-design, using experimentally determined heat-transfer coefficients. The agreement between the quantity of heat dissipated, as determined by experiment and calculated by the equation, was found to be sufficiently close to justify its use. A method has been developed for determining the fin dimensions, utilizing a minimum of material for a variety of conditions of heat transfer, airflow, and metals.
1934-01-01
Technical Paper
340103
J. C. Slonneger
THE paper sets forth a simple and rapid method of obtaining from the indicator diagram data on how, when, and at what pressure combustion takes place in an internal-combustion engine. An indicator diagram predicated upon time-pressure is analyzed by superimposing on the normal diagram a diagram taken without ignition of fuel. This is done either by shutting off the fuel, or by short-circuiting the ignition, as the case may require, and immediately recording a second diagram on the card. Polytropic curves are then constructed on the card and their intersections with the curves of the ordinary diagram indicate the several percentages of effective combustion. Mr. Slonneger uses the term “effective combustion” to distinguish it from “complete chemical combustion” and from combustion losses due to conduction, radiation and leakage. A more technical analysis of Mr. Slonneger's method, according to thermodynamics and chemistry, is given in the Appendix.
1934-01-01
Technical Paper
340104
Hans Fischer
THIS paper points out that, with the solid-injection Diesel-engine, the reliable smooth-combustion performance of the old air-injection type has not been duplicated, especially so with the high-speed Diesel-engine. To get the specific output as high as possible, and to obtain good fuel-economy, it is necessary to have the first part of the combustion approaching the constant-volume cycle, while the rest of the combustion is rather slow. In other words, the rate of burning is a maximum at the beginning and decreases toward the end of the combustion. The rate of burning in a gasoline engine is slow at the beginning and becomes a maximum at the end of the combustion, neglecting the slight after-burning. Comparison is made between the rate of burning of different types of high-speed Diesel-engines and the rate of burning of the gasoline engine.
1934-01-01
Technical Paper
340099
George L. McCain
MR. McCAIN enumerates in the simplest possible form some outstanding features of the new automobile-dynamics, and gives practical commercial reasons for his conclusions. As referred to in the paper, streamlining is the reshaping of bodies to reduce air resistance at a commercial speed of about 45 m.p.h. An analysis of this subject is presented, and the effects of a redistribution of passengers and units are discussed. Riding-quality model-test results and weight distribution are commented upon. A bibliography of streamlining is included. The overdrive is considered by Mr. McCain as part of the airflow car, and the curves show that-with the overdrive-a greater car speed can be reached under favorable wind-conditions, exceeding the curve values, without an excessive engine-speed. Forces acting upon planetary overdrive gears are treated in the Appendix. Much remains to be done toward reduction of wind resistance, in Mr. McCain's opinion.
1934-01-01
Technical Paper
340100
Frederick H. Dutcher
THE purpose of this paper is, first, to set down the methods which have been considered in the effort to develop a gasoline-type engine which will operate satisfactorily on non-volatile fuels, such as furnace or heating oil: Second, to describe briefly commercial examples of the use of these various methods: Third, to analyze the possibilities of these several processes with regard to power and efficiency, comparing them-as well as the results to be expected from the use of motor gasoline-with those of an engine operating on aviation gasoline as a basic standard. Mr. Dutcher concludes that there are cases where horsepower hours per dollar's worth of fuel can be just as-or more-important than horsepower per pound of engine.
1934-01-01
Technical Paper
340097
Stanwood W. Sparrow
MR. SPARROW states that the widespread use of babbitt as a bearing material may be due to the fact that metal-to-metal contact over a small portion of the surface causes the material to soften and crush without damaging the journal or communicating sufficient heat to the remainder of the bearing to destroy the oil film. To some extent copper-lead mixtures are superseding babbitt for main and connecting-rod bearings, and Mr. Sparrow discusses these primarily from the standpoint of their performance in comparison with that of babbitt. Regarding both bearing materials comments are made upon such subjects as cracking, bonding, thickness, life, overheating, disintegration, lubrication and the use of suitable oils, and the results of numerous tests are presented.
1934-01-01
Technical Paper
340098
W. H. Graves, H. C. Mougey, E. W. Upham
THE factors involved in cold starting of automobile engines, including the effects of temperature and oil viscosity on cranking speed and torque, have been known for many years. Many papers have been presented before the various Sections of the Society on these subjects. The S.A.E. crankcase-oil viscosity-numbers, which were adopted in July, 1926, provided for the classification of the lower-viscosity oils at 130 deg. fahr. and the higher-viscosity oils at 210 deg. fahr. It was recognized by 1930 that a classification for winter oils must be based on the viscosity of the oil at the starting temperature, and work was started on this problem. In June, 1933, the 10-W and 20-W oils, which are classified in accord with their viscosity at 0 deg. fahr., were adopted for publication and trial. The results of the use of these oils during the winter of 1933-1934, together with their advantages, are discussed.
1934-01-01
Technical Paper
340096
R. F. Gagg, E. V. Farrar
THE rapidly increasing use of aircraft engines fitted with superchargers for improving the power output at high altitudes has focused attention on means for predicting their performance in advance of actual flight tests in an airplane. A considerable amount of engine testing has been performed in several well-equipped laboratories in the past. These results have been carefully compared to determine the degree of similarity of the performance of these engines, and to form conclusions from which the performance of other engines may be predicted. Since the gear-driven centrifugal supercharger has demonstrated its superiority for use at moderate altitudes over other types on the grounds of simplicity, capacity, weight and space requirements, the data considered are almost entirely concerned with this type. It is shown, however, that naturally aspirated engines have quite similar characteristics.
1934-01-01
Technical Paper
340094
A. M. Rothrock
THIS combustion study was made in a high-speed compression-ignition engine. A high-speed motion-picture camera and an optical indicator were used to take motion pictures of the flame travel and the pressure development during combustion in the N.A.C.A. combustion apparatus. Tests were made in which both the injection-advance angle and the engine-coolant temperature were varied. The results show that, in a compression-ignition engine with a quiescent combustion-chamber, the flame first appears in the spray envelope and from there spreads to other parts of the chamber. The course of the combustion is controlled by the temperature and pressure of the air in the chamber from the time at which the fuel is injected until the time at which combustion starts. The conclusion is presented that, in a compression-ignition engine, the ignition lag should be decreased to the largest value that can be used without excessive rate of pressure rise.
1934-01-01
Technical Paper
340092
Jarvis C. Marble
THIS converter is based on the turbine principle. The major parts consist of a pump wheel and a turbine wheel mounted to rotate in a common working chamber in a stationary casing in which the hydraulic or working fluid is circulated in a closed path of flow. The turbine wheel is usually provided with three rings or stages of blading working in conjunction with two rings of stationary guide blades carried by the casing. Some of the statements made by Mr.
1934-01-01
Technical Paper
340089
Rex B. Beisel, A. Lewis MacClain, F. M. Thomas
THIS paper presents the results of coordinated research by The Pratt & Whitney Aircraft Co. (engines), the Chance Vought Corp. (airplanes), and the U.A.T. Research Division, all subsidiaries of the United Aircraft & Transport Corp. These studies were directed toward improving the performance of airplanes through reducing the drag of radial air-cooled powerplant installations as nearly as possible to the minimum necessary for adequate cooling. The studies were supported by a considerable amount of experimental data. Extensive wind-tunnel tests provided quantitative measurements of airflow and drag for many combinations of baffles and cowling, and throughout the whole work simultaneous flight-tests checked results and contributed to the final conclusions. The successive stages of baffle development, as well as the experiments with various sizes and shapes of cowling, are discussed. The optimum combination ultimately found is described in detail.
1934-01-01
Technical Paper
340121
W. D. Huffman
CUTTING oils are coolants and lubricants. As lubricants, they lubricate the area between the tool and the chip, and are tool and power preservers. Aside from these functions, they are useful in washing away the accumulated chips, giving a bright and smooth finish and acting as rust preventives. There are two general types of cutting oils, the so-termed soluble or emulsifiable oil and the straight cutting oil. The soluble oils mix or emulsify in all proportions in water; they are primary coolants but also have some lubricating action. There are two types of soluble oils, those which are principally or entirely of mineral-oil origin and those which contain an appreciable amount of saponifiable materials or soaps. The straight cutting oils offer a greater range of composition, and likewise a greater field for individual preference. Mr.
1933-01-01
Technical Paper
330044
Oscar W. Schey
SINCE the power output of an engine is practically proportional to the weight of the charge, the object has been to increase the weight of the charge burned. The weight of charge inducted by an aircraft engine and the supercharger power required to supply this charge depend among other factors upon how completely the engine is scavenged. In the conventional four-stroke-cycle engine only the exhaust gases in the displacement volume are forced out of the cylinder by the piston on the exhaust stroke; consequently, the engine cannot induct a charge of greater volume than that of the displacement volume, whereas if the clearance volume could be scavenged also, the engine could induct a charge equal to the displacement plus the clearance volume.
1933-01-01
Technical Paper
330049
A. H. R. Fedden
WIDER use of air-cooled engines in aircraft, considerable reduction in engine volume, and improved fuel consumption are predicted by Mr. Fedden in tracing the course of the next ten to fifteen years in aircraft development. Pointing out that in accordance with Prandtl's theories, startling innovations in aerodynamics are not to be looked for, and that improvement of aircraft will probably follow the line of improvements in detail, the author considers the effect on future aircraft-engine design of such detailed improvements. Piston-connecting rod-crankshaft linkage will survive, he believes. Higher compression ratios will rule, and radical innovations in engines will probably be tried first on automobiles.
1933-01-01
Technical Paper
330059
D.D. Robertson