Re: Concorde noise (was: Concorde's other customers)

Date:         10 Dec 97 04:05:03 
From:         Chris Dickson <cd@cray.com>
Organization: Cray Research, A Division of Silicon Graphics Inc.
References:   1 2 3 4
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Karl Swartz wrote:
> There was also the matter of engine noise on takeoff.  Having heard
> a Concorde departure when the aircraft was about fifteen miles out
> from Heathrow, I can easily understand why nobody wanted the thing
> around.  The racket must be horrific up close.

I'd always considered Concorde's reputation for noise to be somewhat
overblown.... Until, that is, I happened to be collecting my car from
the long term car park at LHR (next to one of the runways) just as one
took off. The noise was physically painful - loud enough to set off the
burglar alarms in most of the cars parked around mine.

I later talked to the car park attendant, and he told me that he'd
noticed that the noise was much louder on days with dense low-level
cloud cover (as was the case at the time). He said that the car alarms
didn't generally go off on clear days, but almost always did on cloudy
ones.

Can anyone suggest an explanation for this? I've speculated that it may
have somthing to do with the air density/temperature/moisture content.
Does anyone  know how/if these factors affect noise propagation, and if
they're something that have to be, or ought to be considered in aircraft
noise monitoring/prediction?

--
Chris Dickson			               SGI / Cray Research
Performance modeler			       655F Lone Oak Drive
Vector servers, simulation & modeling              Eagan, MN 55121
email: cd@cray.com                        Tel: (+1) (612) 683 5375