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84*1619

Shidding of Pr o p* Fan Cabin Noiae by tbe Fuaelage Boundary Layer

D.B. Hanson

Hamilton Standard, Div. of United Technologies, Windsor Locks. CT 06096, J. Sound Vib.. 92 (4). pp 591-598 (Feb 22.1984) 6 figs, 16 refs

Kay Word*: Aircraft noise. Interior noi*e, Noise barrier*

Recent flight test* of a prop-fen (advanced t ech no tog y turbo-prop) model mounted on a business aircraft revaeled noise leve(s on tha fusaiage surface oonsiderabły towar than was expactad from theoretical cakulattons and other test experi-anca. In this peper tha rola of the fusaiage boundary layer in shialding the surface from noise vie classical refraction effects isexamined.

Kay Words: Aircraft noise. Aircraft Windows, Interior noise

Analytkal and experimental procedura* were used to predict tha noise transmittad through double wali Windows Into the cabin of a twin-engine G/A aircraft. Tha analytical model was applied to optimize cabin noise through parametric variation of the structural and acoustic parameters. Tha parametric study inc lud es mass addition, increase in pl exi-glass thickness. decrease in w indów size. increase in window cavity depth, depressurization of the spece betwean the two window platas, replacement of tha air cavity with a transparent viscoelastic materiał, change in stiffness of the plexi-glass materiał, and diffarant absorptive materiał* for the interior walls of the cabin.

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84*1620

Influence of Phyacal and Air Traffic Conditiona on Aircraft Noiae Fmiasion to tbe Ground (Einfluas der phyakaliachen und flugbetriebbchen Bedingungen a uf die Fluglaermimm imion am Bod en)

U. Issermann

Max-Planck-lnst. fuer Stroemungsforschung. Goet-tingen, Fed. Rep. Germany, Rept. No. MPIS-11 / 1982, ISSN-0436-1199,111 pp (Oct 1982) N84-11159 (In German)

Kay Word*: Aircraft noise

Tha dapandanca of form and size of aircraft noise zona* on tha physical and air traffic condittons is investigated. Tha acoustic quantiti*s requirad to determine the aquivalant noise levef ara axplalnad. A method to calculate the noise laval curves is prasa mad. Tha form of tha noise mectrum has a strong effact on tha damping of tha waves in tha atmosphare.

84-1622

Relatioiirfiip Bctween Static, Flight, and Simulated Flight Jot Noiae Measurements

R.S. McGowan and R.S. Larson

Pratt & Whitney Aircraft Group, East Hartford. CT,

Al AA J.,_22_(4), pp 460-464 (Apr 1984) 3 figs, 13

refs

Kay Words: Aircraft noise. Jat noise, Noise maasurement

Jat noise data ara acquired in three diffarant forms: static. flight, and simulated forward flight. Often data must ba transformad from ona typa to one of the other two. A number of studies exist defining tha ralationship batwaen thasa three typa* of meesurements. Thasa studia* ara de-ficient becausa thay do not explicitly co ns id ar tha jet noise sourca charactaristics or do not daarly distinguish betwean mean square prassura, powar spactral density, and one-third octava band sound pressure level meesurements. In the current study, the reletionships between static, subsonic flight. and subsonic simulatad forward flight one-third octave band sound prassura iaval meesurements were dafined.

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84*1621

Study of Noiae Transmuaion through Double Wall Aircraft Witowa

R. Vaicaitis

Modern Analysis, Inc., Ridgewood. NJ, Rept. No. REPT 3, NASA-CR-172182,93 pp (June 1983)

N84-11884

84*1623

Numerka! Siraulation of Tran eonie Flutter of a High* Aepect-Ratio

K. Isogai

Natl. Aerospace Lab., Tokyo, Japan, Rept. No. NAL/TR-776T. 21 pp (Aug 1983)

PB84-135177

Kay Words: Aircraft wings, Flutter, Numerical analysis, Simulation

Numer ical simulation of transonic flutter of a wind tunnel flutter model of a htgtvespect-ratto transport wing włth

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