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1957-01-01
Technical Paper
570030
J. A. Joyner
THIS paper deals with cavitation pitting where vacuum bubbles exist. Experiments are described which attempt to correct this condition where plating of liners varied in composition and thickness. It was concluded that a nickel-chrome plating has very good resistance to cavitation-pitting attack. Investigation of cylinder-wall vibration was made to find out about the cause of cavitation. Minimum liner wall vibration results with use of a 2-piece heavy wall liner and a piston with 20% less clearance. Endurance tests prove that on these pitting has been eliminated.
1957-01-01
Technical Paper
570025
N. D. Sanders, F. C. Laurence
EQUATIONS relating to noise outside a turbulent jet to the turbulent velocities inside the jet have been derived making use of Lighthill's suggestion that the actual flow field can be simulated with a stationary field of quadrupoles. Hot-wire anemometer techniques were applied to a 3V½-in. air jet to measure the turbulent structure of the mixing region. These measurements and the previously derived equations were used to estimate some of the characteristics of the sound field. The estimated characteristics were found to be in good agreement with the experimentally measured sound field of a full-scale turbojet engine.
1956-12-01
Standard
AIR64
This AIR is intended as a status report on the of E.C.S. to date in dealing with the problem of equipment cooling in present and immediate future civil transport aircraft. Subsequent revisions to this AIR will follow as more information is gathered on this subject.
1956-12-01
Magazine
1956-11-01
Magazine
1956-08-01
Magazine
1956-03-15
Standard
ARP476
This document describes guidelines and methods of performing the safety assessment for certification of civil aircraft. It is primarily associated with showing compliance with FAR/JAR 25.1309. The methods outlined here identify a systematic means, but not the only means, to show compliance. A subset of this material may be applicable to non-25.1309 equipment. The concept of Aircraft Level Safety Assessment is introduced and the tools to accomplish this task are outlined. The overall aircraft operating environment is considered. When aircraft derivatives or system changes are certified, the processes described herein are usually applicable only to the new designs or to existing designs that are affected by the changes. In the case of the implementation of existing designs in a new derivation, alternate means such as service experience may be used to show compliance.
1956-03-15
Standard
ARP85C
Air Condiitioning System - General - Dealing with Design Features. Air Conditioning Equipment - Commercial Passenger - Delaing with features. Applicable only to commercial passenger carrying aircraft. Desirable Design Features - General information for use of those concerned in meeting requirements contained herein.
1956-03-01
Magazine
1956-01-01
Technical Paper
560154
W. P. MICHELL, W. E. DAY
1956-01-01
Technical Paper
560152
L. M. BALL
SUMMARY This paper discusses engine noise during car acceleration. The modern automatic transmission is not only a most important factor in the amount of acceleration which can be achieved but is also the element which controls engine speed (and noise) during acceleration. Various types of transmissions are discussed in respect to the relationship between engine speed and car acceleration. These are presented in the form of curves and the basis of an ideal curve is established.
1956-01-01
Technical Paper
560153
D. R. WHITNEY
1956-01-01
Technical Paper
560177
H. A. REYNOLDS
1956-01-01
Technical Paper
560275
J. M. Tyler, R. Krieghoff
1956-01-01
Technical Paper
560240
ALAN R. SCHRADER
Two phases of the U. S. Naval Engineering Experiment Station's current investigation of cavitation erosion in diesel engine coolant systems are described. The first phase is concerned with accelerated cavitation tests as conducted with a magnetostriction apparatus. Various materials and test arrangements were included in the studies. The second phase of the investigation covered the measurement of cylinder liner and block vibration in diesel engines wherein cavitation erosion damage was known to exist. This analysis indicated that the principal source of vibrational energy in the area of cavitation damage was the resonant vibration of the cylinder liners as excited by the impacts of piston slap and cylinder firing pulses.
1956-01-01
Technical Paper
560100
G. L. GETLINE
The reliability of airborne equipment is related to the thoroughness of the environmental test program. The importance of being able to rationalize the environmental tests in terms of the actual flight environment is stressed. Present environmental vibration test procedures, which are based for the most part on flight data obtained in propeller driven aircraft, are reviewed. It is shown that such procedures cannot be applied to turbojet aircraft. An environmental test procedure is proposed which utilizes the latest type laboratory shaker and control equipment to provide a vibration and noise analogue of an aircraft. The penalties of “over-testing” are pointed out. In conclusion, an environmental test specification is compared to an insurance policy, and it is urged that its implications be fully understood.
1956-01-01
Technical Paper
560085
B. A. ROSE
1956-01-01
Technical Paper
560027
J. M. Tyler, G. B. Towle
AN effective method for silencing, to an agreeable amount, the noise produced by a jetengine exhaust system is described in this paper. The principle employed is based on the fact that high-frequency noises are more rapidly attenuated with increasing distance from the source than low-frequency noises. Basically, the performances of the developed silencers are to reduce the amount of noise of a jet exhaust by increasing the frequency range of the noise produced. Full-scale silencers have been developed for use as ground equipment. Scale models of airborne silencers have been studied and show promise for full-scale development, however, further studies are required to minimize disadvantages to airborne applications.
1956-01-01
Magazine
1955-11-01
Magazine
1955-09-01
Magazine
1955-03-01
Magazine
1955-01-01
Technical Paper
550251
Arthur A. Regier
THIS paper presents a brief historical review of the quest for information concerning the mechanism of aircraft noise generation. It is shown that, after a number of false hypotheses, the noise of propellers was finally traced to the principal aerodynamic loads of the blades. The intensity and characteristics of the noise can now be predicted theoretically from knowledge of the geometry and operating conditions of the propeller. With regard to jet noise, the picture is not so clear. The actual mechanism of noise generation is still somewhat obscure. Included here is a resume of United States and British work on determining the actual source of noise. Experiments on devices for reducing noise are also discussed.
1955-01-01
Technical Paper
550250
Adone C. Pietrasanta,, Richard H. Bolt,
NOISE has two aspects: (1) subjectively, it is any unwanted sound; (2) objectively, it is characterized by many variables. The subjective view is important in determining the response of people to aircraft noise and in establishing engineering design objectives for noise control. The engineering of noise control deals with the objective aspect in three parts: 1. The noise source — characterized by its total noise power output and the distribution of this power with respect to frequency and space. 2. The path — propagation in structures, through the air, and over terrain as influenced by properties of materials, geometry, meteorological conditions, and topography. 3. The received noise — its sound level, frequency spectrum, time pattern, and other variables as required to correlate with the subjective response of man in the aircraft, on the line or in the community.
1955-01-01
Technical Paper
550255
Robert E. L. Fogle, Holden W. Withington
THE efforts of one manufacturer to solve the problem of jet-engine noise suppression when test facilities are near residential communities are reported here. The authors describe the construction of several suppressors and give data on their effectiveness. Their experience covers a run-up suppressor and also a portable unit of the water-injector type-both developed for the B-52 airplane, and a water-spray muffler for ramjet engines. They emphasize the fact that, since World War II, airplane manufacturers have been required to spend more and more time, effort, and money in attempts to cut down the noise produced by airplane and guided missile powerplants. The efforts of their company, they point out, are similar to those of other airplane companies. It appears that the problem is growing. No simple solution is yet in sight.
1955-01-01
Technical Paper
550253
C. E. Rosendahl
Control of aircraft noice in airport vicinities lies in two general directions. The first is in control of noise at its source — in the aircraft itself. The second is in the procedural measures in operation of the aircraft and is the subject of this paper. Measures adopted by the NATCC for application at the major civil airports in the New York-New Jersey metropolitan area are described here. They include: 1. A preferential runway utilization plan. 2. Accelerated climbouts stressing rapid gain of altitude. 3. Restriction of ground run-ups to specified locations. 4. Adoption of procedures particularly adapted to an individual airport. 5. Receipt and analysis of the public's complaints relative to aircraft noise. 6. A public information program designed to acquaint airport neighbors with aircraft matters. 7. Continuous effort at obtaining full compliance with adopted procedures.
1955-01-01
Technical Paper
550254
Joern Schmey, Ralph M. Guerke
ORIGINS of propeller noise and possible means for its reduction both within and external to turboprop aircraft are discussed here. Decreasing the tip speed and increasing the number of blades of turboprop propellers result in quieter performance within the aircraft but with a heavy weight penalty. Changes in certain aircraft design parameters, such as increasing clearance between fuselage wall and propeller tips, can also reduce internal noise and vibration. Improvements in external turboprop noise can be achieved by use of quiet-type propellers, increased rate and angle of climb, preferential runways, adequate airport zoning, and sound-dissipating foliage and ground covers.
1955-01-01
Technical Paper
550265
F. B. Stulen
VARIOUS structural problems encountered in the design of high-speed turboprop propellers are discussed in this paper. Formulas for a number of design factors are also given here. These include: 1. Blade efficiency. 2. Power capacity. 3. Advance/diameter ratio. 4. Limiting tip speed. 5. Periodic lift. 6. Propeller normal force and moment. The paper also describes two types of vibration occurring with turboprop installations: 1. First-ordered aerodynamically excited vibration. 2. Subsonic stall flutter. The author shows how these vibrations may be accurately predicted and controlled by proper design of the propeller blades.
1955-01-01
Technical Paper
550269
Robert Meagher, R. L. Johnson, K. G. Parthemore
A BETTER knowledge of the nature and causes of preignition and of its frequency during normal engine operation has been obtained by instrumenting a 9/1-compression-ratio engine on a test stand and an engine in an automobile with rate of change of pressure pickups. Photographic records of the oscilloscope traces produced by this instrumentation have enabled the determination of: 1. The relative tendency for preignition or postignition to occur and the relation of these phenomena to engine or car operating conditions. 2. The physical causes of the noises accompanying the several types of preignition. 3. The effect of retarded spark timing on deposit-induced preignition. 4. The significance of the “key-off” method of fuel rating.
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