Re: MD-90?

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         17 May 95 01:06:29 
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>McDonnell Douglas claims that the
>aircraft is the quietest jet transport.  From what I have read,
>this is a result of the use of the IAE V2500 engines (the largest
>and heaviest ever rear-mounted), location of the powerplants and
>some "innovative cowling design".

Location is a major contribution -- the wings make a significant
contribution towards "hiding" the engine noise, according to articles
on the MD-90 in AW&ST.  Another article I recently read (in Airways?)
commented at length on the nacelle and also pylon design and their
contribution to noise reduction.

Note that some A320s also have V2500 engines, not exactly the same
model but close, yet the MD-90 is significantly quieter.  (I'm not
sure how a V2500-equipped A320 compares to one with CFM-56 engines
in terms of noise.)

Nit: the DC-10 and L-1011 both have a rear-mounted engine that is
larger and heavier than a V2500!  Rather different location just the
same, of course, and a very different sort of pylon -- on both the #2
engine actually hangs from the pylon, not all that much different from
the pylons on the wing-mounted.  I suspect the paired engines on each
side of a VC-10 or Il-62 are larger and heavier than a single V2500,
too, so from a structural standpoint they may be no less of a problem.

Karl Swartz	|INet
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