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1968-04-29
Technical Paper
680279
Nelson F. Rekos
Discussion and outline of propulsion research problems expected to be encountered in developing the required new propulsion technology for New Generation Engines. Author bases discussion on the assumption that demands and requirements generated by an aircraft transportation system will indicate the desired type of aircraft and propulsion system. However, final system selection will probably be made on a cost-effective basis.
1968-04-29
Technical Paper
680276
W. A. Reinhart, G. J. Schott
Propulsion system requirements for subsonic and supersonic transports in the 1975 to 1985 period are presented from an airframe manufacturer’s point of view. The number one problem will be noise, with different detail problems to be solved for subsonic and supersonic transports. With respect to engine cycles, it is shown that a new round of subsonic engines can be expected; for supersonic transports the cycle is needed which better matches both supersonic and subsonic flight requirements. A plea is made for the start of a long-range program aimed at understanding the fluid How details of unsteady compressor operation. Total aircraft power requirements should be studied, allowing for new packaging concepts and certification rules. It is shown that opportunities exist which by 1975 may lead to practices significantly different from those now employed.
1968-04-09
Technical Paper
680248
John W. Carter, O. Dean McWilliams, Harvey A. Knell
The Cushion Hitch is a unique application of vibration absorber theory to a self-propelled tractor-scraper. The scraper mass is utilized as a damper for suppressing predominate bouncing motions of the tractor unit. A more comfortable and safer operator ride, with increased productivity, results from the Cushion Hitch application. This paper describes development of the early prototype design as well as the final production version. Particular emphasis is given to both the hydraulic and the structural characteristics of the system.
1968-02-01
Technical Paper
680071
C. K. Murphy, P. A. Bennett
The use of multigrade (V.I. improved) oils in automotive engines has increased significantly in recent years. However, the performance of these oils in terms of factors such as oil economy, wear, and noise, is not always equal to that of single grade oils. Although the initial viscosity of multigrade oils is related to both the base oil and the V.I. improver, the viscosity decreases with use, with the primary factors determining the magnitude of the change being the degree of shear and the characteristics and concentration of the V.I. improver used. This decrease in viscosity has been assumed to be the cause of the decreases in oil economy that may occur with oil use. However, viscosity changes are not believed to be the primary factor responsible since similar oil economy changes have also been observed for single grade oils. Nevertheless, the characteristics and concentration of the V.I. improver used can be a significant factor influencing oil economy.
1968-02-01
Technical Paper
680050
Edwin P. Lehmann
Vehicle noise resulting from vibration excited by the drive axle can be measured and controlled. Modifying the gear tooth geometry to assure the optimum design can then be achieved. Further benefits are obtained through determination of the critical path of vibration transmission from the axle into the passenger compartment, pointing the way to vehicle suspension revisions for additional noise control. A vehicle sensitivity index number, and a gear set quality index number are derived which can be matched, thereby specifying a gear set of known quality level for a vehicle of known sensitivity.
1968-02-01
Technical Paper
680023
Tetsuya Seino, Susumu Shimamoto
Abstract All the primary inertia forces and/or moments generated by engines having three cylinders or less are not normally in balance by themselves and thus may be a great source of vibration for the frame supporting the engine. If the mass distribution of the crankwebs is selected in a proper manner, it is possible to determine arbitrarily the directions and the length ratio of principal axes of ellipses, which are obtained as Lissajous diagrams of inertia force and moment. This method can be effectively applied to reduce vibration in the frames. In this paper the appropriate inertia force and moment ellipse equations are developed and the analysis is outlined for optimizing the engine balance. Also the fundamental properties of the linear vibration systems excited by the elliptical forces as well as some experimental examples of elliptical excitation are detailed.
1968-02-01
Technical Paper
680090
Bruce D. Van Deusen
This paper reviews experiments for determining human response to vibration and interprets them in the vehicle vibration context. It reviews the author's research and compares it with findings of other investigators. From the results of vehicle tests, it is concluded that properly weighted “acceleration variance” is a meaningful measure of vehicle vibration. For a single vehicle subjected only to surface profile changes, a single number summed over all frequencies can be used. For two or more vehicles with different vibrational characteristics, acceleration variance must be computed in several frequency bands to yield correction factors that define the nature of the vibration.
1968-02-01
Technical Paper
680081
John H. Lienesch, Wallace R. Wade
Continuing Stirling engine development at General Motors has uncovered advantages of the powerplant never before fully appreciated. Smoke, odor, noise, and exhaust emission measurements indicate the attractiveness of the engine for applications in a “social” environment. Design details, particularly the external combustion system, are described here only in relation to low emission level. Measurements indicate that smoke and odor are practically undetectable. Sound measurements demonstrate the relative quietness of the engine. Additional data show that exhaust emissions, while very low, exhibit a strong dependence on burner design, air-fuel mixture ratio, burner inlet temperature, and exhaust recirculation.
1968-02-01
Technical Paper
680005
A. Lloyd Nedley
One cause of vehicle disturbance is smooth road shake. Manufacturers are attempting to reduce vehicle sensitivity to shake input forces from tire-wheel assemblies by changing suspensions and body-frame structure, stiffness, by tuning engines on rubber mounts, relocating body mounts, and so forth. The similarity of tire nonuniformity and wheel radial runout, and the laboratory and production techniques for matching tire and wheel are described. The conclusions reached are that matching tires to wheels would be an effective stop-gap measure; that the ultimate goal is improvement in tire uniformity and wheel runout to the point where matching would be unnecessary; that tire lateral force variation and lateral wheel runout are not related to smooth road shake.
1968-02-01
Technical Paper
680004
John A. Main
Abstract Wheel runout can be reduced by better wheel design, coupled with improved manufacturing processes. For example, it appears that runout is less if the spokes are eliminated, providing a continuous flange, thus permitting a reduction in press fit. The resulting disc is easier to form, tooling and maintenance of dies have been simplified, and when the disc is assembled to the rim, it should be more uniform, with less concentrated distortion. A new machine, to be used on a semiproduction basis, is proposed for measuring wheel runout more accurately.
1968-02-01
Technical Paper
680003
Douglas D. Maclntyre
Abstract The problem of wheel/tire induced vehicle vibration is now of such proportions as to be of interest to both vehicle builders and users. This paper includes a description of the factors involved in generating the vibrations and a discussion of several approaches and/or solutions to the problem.
1968-02-01
Technical Paper
680224
John M. Wetzler, Raymond L. Chaney
The Allison 250 turboprop program is reviewed including engine characteristics, the development program, FAA certification, and development to higher power ratings. Market and installation programs are reviewed including general aircraft turbine engine trends, turbine engine market potential, and a discussion of the justification and merits of small turboprop aircraft. Various 250 turboprop installations are discussed.
1968-02-01
Technical Paper
680229
Donald P. Hansen, Carl R. Goulet
This paper delves into the electrical characteristics developed in automotive equipment and how these same characteristics meet today’s aircraft requirements of light weight, low-speed performance, higher outputs, etc. It covers the problems of adapting automotive electrical equipment, such as vibration characteristic differences, mounting and drive systems, and cooling requirements under continuous high performance outputs. Differences in wiring systems between aircraft and automotive systems, the requirements of self-excitation, and the requirements of operation without the battery connected in from the standpoint of limited voltage spikes are discussed. Specialized requirements such as radio interference suppression, use of static transistorized regulators, and qualification requirements are also presented for consideration in the use of automotive electrical components.
1968-02-01
Technical Paper
680223
Herbert O. Fisher
The problem of aircraft noise is reaching critical proportions, with the ever-increasing number of jets and the coming introduction of the 747 and SST. The communities surrounding airports are becoming more and more intolerant of this noise. Although engineering technology will solve some of the problem with advances in engine design, the final solution rests with the federal government. Only on the federal level can effective noise standards be promulgated and applied to all aircraft through the certification process. This solution is discussed in detail.
1968-02-01
Technical Paper
680278
William H. Sens, Robert M. Meyer
This paper discusses the potential characteristics of powerplants of the generation beyond the generation of engines currently in development. These powerplant possibilities are related to historical trends in powerplant characteristics and component technology. Future powerplant requirements are examined in the light of potential technological advances. The implication of improved control of aerodynamics and mechanical design, improved materials, advanced fuels, and control of noise and smoke generation are discussed.
1968-02-01
Technical Paper
680335
J.A. MORRISON, BOEING
New approaches to problems such as noise, temperature control of accessories and equipment in the nacelle, as well as improved safety features, are necessary in a modern high by-pass engine installation. The means of supporting the engine, cowling design, and maintainability features combine to improve the state of the art that a more economic airplane will result.
1968-02-01
Technical Paper
680338
J. M. S. Keen
The Rolls-Royce family of large high by-pass ratio engines has resulted from a long study aimed at providing the optimum compromise between first cost, operating cost, weight, and noise level for the new generation of subsonic civil transport airplanes. This paper considers the design approach applied to some aspects of reliability, failure detection, and rectification in these engines and also the mechanical implications of some noise-suppression features.
1968-02-01
Technical Paper
680498
JOHN B. CLARK
Under high speed, high temperature driving conditions aluminum water pumps can be damaged by cavitation and/or erosion. Some antifreeze formulas increase the cavitation- erosion damage over that obtained with plain water. Therefore, selection of a compatible antifreeze is an important way of minimizing aluminum pump cavitation-erosion damage. Three laboratory tests are described which attempted to predict antifreeze cavitation-erosion performance in aluminum water pumps in cars in the field. Of the three tests, a high speed, high temperature laboratory pump test gave most reliable antifreeze performance prediction. A venturi apparatus gave results that correlated well with actual pump tests and showed promise as a screening tool for antifreeze evaluation, alloy selection, etc. A vibrator test fixture did not correlate well with pump tests. Other means of reducing aluminum pump damage such as use of different aluminum alloys and reducing pump speed are also briefly discussed.
1968-02-01
Technical Paper
680406
R. E. Wolfgang Hempel
The basic thermodynamic and operating advantages of using turbocharging with diesel engines are summarized and the question is posed as to whether turbocharging is the best method from an acoustic point of view. The generation, transmission, and radiation of noise in turbocharged engines are described and the interaction of the reciprocating engine and turbocharging system is discussed. An indication is given as to how acoustic improvements are possible by taking suitable measures at the drawing board. The conclusion is drawn that for increases in output, turbocharging is the most favorable method for creating a “quiet engine.”
1968-02-01
Technical Paper
680405
Otto Cordier, Gaston Reyl
Various noise causes are characterized by means of noise sources and noise paths. Engine noise is differentiated from that of the plant. Well-known phenomena and empirical data gained from noise measurements are dealt with briefly. Statistically confirmed interrelations are used to predict engine noise with sufficient accuracy, in particular from the mean piston speed. It is also shown that noise generated by cooling blowers can be accurately estimated from pressure and delivery volume (blower capacity), and that circumferential speed is not an adequate criterion. Typical examples show the effects of various measures on mechanical, combustion, and blower noise.
1968-02-01
Technical Paper
680407
Gerhard E. Thien
This paper describes a newly constructed research facility which was specifically designed for noise reduction work on internal combustion engines. Various approaches for reducing engine noise are discussed, and a method which permits locating individual sources of structure-borne sound is reviewed. A measuring system for airborne sound, radiated from the engine surfaces, is described. Some new findings and new problems encountered in noise reduction work are discussed.
1968-02-01
Technical Paper
680571
Joseph R. Harkness
Two balancer developments are followed through the conception and development stages into production. One design utilizes gear driven auxiliary flyweights, and the other, an oscillating counterbalance driven by crankshaft eccentrics. Vibration reductions up to 85% have been realized.
1968-02-01
Technical Paper
680584
Shellie O. Williamson
Modern data acquisition methods combined with new testing and analysis techniques are revolutionizing product design and development. Detailed analysis of recorded vehicle drive-line data has given today's engineer new insights into drive-line dynamics. This paper discusses how vehicles can be analyzed as a series of torsional springs and inertia masses. A two axle, 300 hp, 15 cu yd earthmoving tractor scraper (model 621) is used to illustrate significant factors. Main emphasis is on drive-line resonant torsional vibrations and shock loading. Diesel engines as torsional vibration exciters and transmission clutches as the major shock load producers are covered in some detail. How analog computers can effectively be used to facilitate vehicle development is briefly discussed.
1968-02-01
Technical Paper
680586
Lyle F. Yerges
The engineer is often faced with the problem of forecasting the effects on human beings of the sound produced by equipment operating within the environment in which they live or work. A detailed measurement of sound pressure levels throughout the frequency spectrum is necessary for a complete analysis, but the standard sound level meter is probably adequate for most purposes and nearly as accurate as more complex computations. This paper provides useful criteria for specifying performance of equipment or for limiting the exposure of human beings to noise in certain acoustical environments.
1968-02-01
Technical Paper
680753
P. E. Rentz
Abstract The design of vibration tests involves satisfying both objective and subjective goals with uncertainty about the true reliability of the design. A procedure is outlined whereby the constraints, goals, future states of nature, and candidate test designs are identified. A general statistical decision theory model is used to evaluate the designs based on maximizing expected utility. The paper emphasizes utility theory and utility function formulation. An example spacecraft test problem is presented.
1968-02-01
Technical Paper
680747
Jerome E. Ruzicka
This paper presents the state-of-the-art of active vibration and shock isolation, with theoretical considerations limited, to idealized single-degree-of-freedom systems. Servocontrol systems postulated for use as active isolator mechanisms are reviewed with emphasis placed on active isolation systems that have been reduced to practical operational hardware. Performance characteristics of mechano-pneumatic and electrohydraulic isolation systems are discussed in detail and are compared to those of conventional passive isolation systems. Experimental data are presented to demonstrate performance characteristics of these active isolation systems in aerospace applications involving the protection of missile inertial guidance platforms during launch and a jet aircraft pilot during severe turbulence encounters. Optimization analysis and synthesis concepts are discussed relative to the design of active vibration and shock isolation systems.
1968-02-01
Technical Paper
680750
Erich K. Bender
Some of the fundamental limitations of roll control and vibration isolation are analyzed and discussed. Optimum roll responses to a step input in lateral acceleration are derived from the calculus of variations. The responses show that a pendulous suspension (where the roll center is above the passengers) can be made to exert zero net lateral acceleration on passengers; whereas, a finite lateral acceleration will always be present during maneuvers of vehicles equipped with conventional suspensions (where the roll center is below the passengers). The lower limitation on roadway-induced vibration is presented as a trade-off between vibration and the clearance space between the sprung and unsprung masses or between the sprung mass and the roadway. Finally, the substantial benefits accruing from the use of preview control (where the roadway ahead of a moving vehicle is sensed) are presented.
1968-02-01
Technical Paper
680751
David Alan Bies
A vibration isolation system is investigated theoretically and experimentally which combines an active element with a passive system. The resulting system, here called a hybrid vibration isolation system, seeks to give stiff response at low frequencies and soft response at high frequencies without a large resonant response at intermediate frequencies. It is shown that fairly good response can be achieved with reasonable choice of operating parameters.
1968-02-01
Technical Paper
680748
Julian Wolkovitch
An introduction is given to some mathematical optimization techniques applicable to shock and vibration absorbers and isolators. Simple tutorial examples are presented illustrating the Phillips and Wiener procedures and the method of Minimization of Auxiliary Effort. For shock inputs, optimization criteria of the form “minimize the maximum value of x(t)” are important. It is shown that these can be approximated by the more tractable criterion “minimize with suitable T” using conveniently small values of n. Published applications of optimization techniques to shock and vibration are briefly reviewed.
1968-02-01
Technical Paper
680688
W. M. Magruder
Successful development of a commercial transport airplane depends primarily on satisfying three fundamental aspects: safety, economics, and community acceptance. In turn, these factors are heavily influenced by the airplane configuration, operational characteristics, and engineering design features. This paper presents some of the major considerations leading to the development of the L-1011 configuration selection, and the operating requirements used in establishing the basic design of the airplane.

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