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1969-02-01
Technical Paper
690614
R. W. Mustain
This paper presents the philosophy and requirements for an integrated aerospace dynamic program. This aerospace dynamic program encompasses a full range of dynamic tests and analyses required to evaluate, develop, and qualify an aerospace vehicle. This presentation commences with a brief history of dynamic tests and analyses conducted during the past two decodes and continues with some notes on the development and design of aerospace vehicles utilizing present-day analytical and test techniques. Analyses are required to establish dynamic criteria and structural integrity of the aerospace vehicle. Dynamic criteria include shock, vibration, and fluctuating pressure excitations during various phases of the vehicle’s life. Thus, criteria should be predicted for the transportation phase as well as for the flight mission.
1969-02-01
Technical Paper
690613
H. L. Leve, F. A. Biehl
The paper discusses the analytical procedures required in computing the engine support system dynamic loads induced by a fan unbalance. The detailed analyses involve the coupling of pylon and engine vibration modes in the modal coordinate system and the determination of the steady state response due to an unbalance in the rotating fan. Gyroscopic effects, engine case ovalization flexibility, and a redundant restraint to an external support are investigated. Graphs are presented that summarize the computed results and show the sensitivity to gyroscopic effects.
1969-02-01
Technical Paper
690617
David Lubman
Nonuniformities of sound level occur in all reverberant rooms including those used in sonic testing. A theory is presented which describes these variations statistically in terms of analysis bandwidth and room reverberation time. The theory applies above a certain cutoff frequency and in regions remote from room boundaries. These nonuniformities produce uncertainty in the room averaged sound spectrum levels leading to potentially serious risk of undertest or overtest. A methodology is proposed whereby the risk of any degree of undertest or overtest can be predicted and controlled in advance. The methodology employs hypothesis testing applied to the known statistics of the sound field.
1969-02-01
Technical Paper
690684
Harry Sternfeld, Robert H. Spencer
Helicopter design trends towards increased blade loadings and higher tip speeds have resulted in generation of higher levels of rotor noise. This paper describes experimental programs to establish operating limits which, if observed, will result in rotary-wing aircraft with subjectively acceptable acoustical signatures.
1969-02-01
Technical Paper
690066
Conrad R. Hilpert
The paper explains a failure commonly called “clutch plate flutter” and presents the developed cures. The complete theoretical and practical cases are detailed with mathematics, illustrations, and explanations. It is concluded that flutter is gyroscopic in origin, can be defined mathematically, occurs only in counter-rotating clutches, and can be eliminated by minor design innovations requiring no additional parts.
1969-02-01
Technical Paper
690756
Thomas A. Ballas
In general, noise within an antifriction bearing can be classified as coming from random and periodic sources. The most annoying and preventable come from periodic causes, for example, a nick on a bearing raceway due to handling damage during assembly. As an aid in detecting such periodic sources in a tapered roller bearing, formulas are provided which determine the rate of contact for a specific point on one of the raceway surfaces, that is, cup, cone, or roller. Some experimental evidence demonstrating the worth of such an approach is included.
1969-02-01
Technical Paper
690055
Gerhard H. Junker
The theory of self-loosening of preloaded bolted connections when subjected to vibration is discussed. The significance of self-loosening as a cause of failure is explained, and design guidance to avoid self-loosening is given. The test methods are described and discussed in connection with a newly designed testing machine that yields quantitative data for evaluating locking properties. These methods can be applied to all types of locking elements. Finally, a simplified method for broad scale testing and inspection is proposed.
1968-10-07
Technical Paper
680713
R. E. Pendley, V. Millman
The suppression of noise radiated from turbofan engine installations of commercial transport aircraft has been a subject of continuing research and development studies. This paper discusses some nacelle design approaches being investigated in such studies, and approaches to several problems involved in the development and operation of powerplant installations incorporating noise suppression features. The paper includes some recently obtained theoretical and experimental data on the effects of nacelle configuration on far-field noise distribution and, in addition, several new test techniques for evaluating acoustically absorptive duct-lining durability and cleaning characteristics.
1968-07-01
Magazine
1968-07-01
Standard
J903B_196807
This SAE Recommend Practice establishes for passenger cars, light trucks, and multipurpose vehicles with GVW or 4500 kg (10 000 lb) or less: a. Minimum performance standards for windshield wiper systems. b. Test procedures that can be conducted on uniform test equipment by commercially available laboratory facilities. c. Uniform terminology of windshield wiper system characteristics and phenomena consistent with those found in guides for the use of engineering layout studies to evaluate system performance. d. Guides for the design and location of components of the systems for function, servicing of the system, etc. The test procedures and minimum performance standards, outlined in this document, are based on currently available engineering data. It is the intent that all portions of the document will be periodically reviewed and revised as additional data regarding windshield wiping system performance are developed.
1968-06-01
Magazine
1968-06-01
Standard
J336_196806
This SAE Recommended Practice describes the equipment and procedure for determining the truck cab interior sound level over the upper half of the engine speed range. This practice applies to motor trucks and truck-tractors and does not include construction and industrial machinery.
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.

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