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Viewing 12751 to 12780 of 13422
1934-01-01
Technical Paper
340040
G. W. Smith
1934-01-01
Technical Paper
340049
Arch L. Foster
1934-01-01
Technical Paper
340037
C. B. Veal
1934-01-01
Technical Paper
340063
Guy L. Tinkham
1934-01-01
Technical Paper
340065
MERRILL C. HORINE
1934-01-01
Technical Paper
340070
LOUIS WAIT
1934-01-01
Technical Paper
340071
RALPH L. CRAM
1934-01-01
Technical Paper
340073
Austin M. Wolf
1934-01-01
Technical Paper
340076
Stephen J. Zand
1934-01-01
Technical Paper
340081
Eastman N. Jacobs
THIS paper, which has been awarded the Wright Brothers Medal for 1933, considers first the air forces acting on airfoil sections, their origin, and the nature of the differences between the air forces acting on an ideal airfoil section and on an actual one. These differences, which are due primarily to the action of viscosity, are considered in detail because they distinguish the desirable from the undesirable sections. The effects of viscosity are discussed in relation to the air-flow about the section as affected by a variation of the dynamic scale or Reynolds Number of the flow. Separation of the flow from the airfoil surface, which produces the most marked deviations from the ideal flow, is discussed in detail, considering the effects of varying the Reynolds Number and the initial turbulence of the air. Finally, the paper considers the variation of the aerodynamic properties of sections with changes in the section shape.
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
340085
John B. Wheatley
THIS paper contains a brief discussion of the advantages inherent in a rotating-wing aircraft in regard to its performance and safety as compared to the conventional airplane. An arbitrary criterion is set up that presents the different characteristics which must be possessed by the rotating-wing aircraft in order that it be considered successful and practical, and the criterion is then used to evaluate the merit of the helicopter, the cyclogiro, the autogiro, and the gyroplane. According to the criterion, the autogiro and gyroplane will be superior to the airplane when their pronounced possibilities for high-speed performance are materialized, these possibilities consisting of the inherent ability of the autogiro and gyroplane rotors to attain their maximum lift-drag ratio at any desired forward speed. The cyclogiro is approximately equal in merit to the airplane, while the helicopter is quite definitely inferior.
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
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
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
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
340101
Theodore M. Prudden
1934-01-01
Technical Paper
340102
E. J. Abbott
THE desirability of measuring sound by soundmeter, rather than by listening with human ears, is expressed by the author, who states that soundmeter measurements indicate definitely just what components of noises must be reduced and also just what has been accomplished by any given change. Usually, they may be taken so as to indicate the part responsible for the noise, and even the nature of the defect. He then considers some fundamental characteristics of human ears and of various sounds. The apparent inconsistencies of the mass of data obtained from soundmeter measurements made in connection with practical noise-problems are explained, and the physical problem of what soundmeters measure is presented, together with a discussion of the subject of sound pressure and the use of the decibel scale of sound measurement which includes definitions of the various terms and units employed.
1934-01-01
Technical Paper
340107
C. V. Johnson
THIS paper points out that the shock-absorbing system of the main landing-gear of an airplane must function under the impact of landing and while taxiing on landing fields. The present requirements for impact landing are outlined, and a typical analysis is made to check up a proposed system for a given airplane. The effects of geometrical arrangement of gear, of tire size and of tire rebound are considered. Laboratory methods of testing systems to determine whether the requirements have been met are discussed. The characteristics desired of the shock-absorber system for good taxiing are enumerated, and the effects of various types and arrangements of absorber units on performance are investigated. In conclusion, the paper presents a discussion of the tail-wheel shock-absorber system in which it is brought out that the same criteria that are applied to the main gear apply here, but that the relative importance of various factors is not the same as in the main gear.
1934-01-01
Technical Paper
340105
Frank W. Caldwell
THIS paper treats briefly the aerodynamics of the aircraft propeller, including the effect of selection of the airfoil section, the plan form and the aspect ratio. The aerodynamic characteristics of the propeller as a whole are discussed with some reference to the effect of tip speed and body interference. The stress analysis is dealt with, and methods of measuring the vibration stresses are described in some detail. A short analysis is made of the properties and advantages of some of the materials used for propeller blades. An outline of the development of the control-lable-pitch propeller follows, together with a description of the present-type of hydro-controllable propeller now in use throughout the world. In conclusion, the paper deals with methods of testing propellers to assure their safety in service.
1934-01-01
Technical Paper
340115
Charles O. Guernsey
THE history of the development of railcars or motor trains is reviewed and their economic application discussed. In Mr. Guernsey's opinion, the eventual design for general application will be some reasonable compromise between the past conservative and the present extreme designs. His conclusions are that: Rail motor-trains properly applied can be largely used to hold and regain traffic for the railroads. The principal competitor is the private automobile. Motor trains probably cannot compete with the private automobile or the common-carrier bus, in frequent-stop local service. The cost of operating service per passenger seat should be much less than that of present equipment. Motor trains should be applied for operation over distances and at speeds where the overall time from point of origin to point of destination of the passenger will be less than by competing carriers, whether private or public. Frequency of service must be considered, as well as schedule speed.
1934-01-01
Technical Paper
340113
D. P. Barnard
Abstract RECENT active interest in the use of commercial butane gas as a fuel for highway-transportation equipment, particularly on the Pacific Coast, indicated to Mr. Barnard the advisability of resurveying the field of possible substitutes for gasoline, especially as regards butane. Since rapid developments in the conversion of truck fleets to use butane as fuel took place in the West, Mr. Barnard considers the possibility of the general use of butane in this class of service. After going into detail regarding the chemical properties and performances of butane and gasoline, as well as their economic aspects, Mr. Barnard concludes that an attempt to supply butane under the conditions necessary for highway units eventually would result in a final cost to the operator-on a gallonage basis-higher than that prevailing for regular gasoline. He states that no very widespread use of butane as a fuel could occur without increasing the demand to a status at which the cost would be prohibitive.
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
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
340120
Louis Schwitzer
IT is always the automotive engineer's endeavor to improve automotive vehicular performance. Greater acceleration and higher speeds have been accomplished by a continuous increase of engine sizes, until today further increase by this method is not logical. We are today turning to dual axle ratios and streamlining to accomplish further increases; the former to allay the disastrous effects of the drooping torque-curve at high engine speeds, and the latter to reduce the power to propel the vehicle. Reduction of engine-speed wheel-speed ratios is ideal for high speed but represents a loss in acceleration at intermediate speeds. Reduction of wind resistance of the vehicle, only valuable at high speeds, permits only a slight increase in top speed because of the rapid reduction in power at high engine speeds. Thus a dilemma exists, which can be avoided by forced induction, or supercharging. Forced induction with dual axle ratios and streamlining produces the only complete picture.
1934-01-01
Technical Paper
340027
R. F. Norris
1934-01-01
Technical Paper
340019
Arthur Nutt
1934-01-01
Technical Paper
340018
E. S. Taylor
Abstract The general design problem is considered by reference to the principle of similarity. The principle is briefly reviewed and applied to lubrication, propeller drives, cooling and detonation. It is shown that while small engines should be capable of a larger output per square inch of piston area, in practice the reverse is the case. It is also shown that small engines should, in general, operate at a higher efficiency than large ones. A promising line of attack for improving the lubrication of small engines is indicated.
1934-01-01
Technical Paper
340012
Austin M. Wolf
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