Re: Noise, size, and bypass?

From:         Steve Lacker <slacker@arlut.utexas.edu>
Organization: applied research laboratories
Date:         10 Jan 96 02:01:45 
References:   1 2 3
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kls@ohare.Chicago.COM (Karl Swartz) wrote:
>>The JT8D was designed mostly in the '50s and early 60s!  There are about
>>8,000 of them around, all LOUD!
>
<Karl's calculation of around 12,000 snipped>

I agree, 12,000 is the LOW estimate. The Jt8D is also the basis of the
military engine in the Grumman Intruder too. Plus spares, plus smaller
applications....  its a BUNCH of engines.

>They're also not all loud, relatively speaking.  The MD-80 series uses
>the JT8D-200 series engines which are quiet enough to meet Stage III
>noise requirements.  Older JT8Ds, sans hush-kits, are indeed pretty
>loud, though not as bad as an old JT3 or JT4 from a 707 or DC-8.

Agreed again. When I think "jet noise", its eseentially the sound of a
JT3 that comes to mind, since that was the engine on the jets (707's) I
recall seeing and hearing as a little kid. Old JT8D's are close, but lack
the banshee-shriek of a JT3 or pure jet like a J-57. THOSE are loud
engines!

Also, the JT8D is surely one of the most reliable aircraft engines ever
to see service. My understanding is that P&W developed it in a shockingly
short time span in the early '60s *specifically* to meet Boeing's
requirements for the 727.

--
Steve Lacker	/	Applied Research Laboratories, The University of Texas
512-835-3286	/	PO Box 8029, Austin TX 78713-8029
slacker@arlut.utexas.edu