Path: utzoo!utgpu!attcan!uunet!lll-winken!ames!haven!purdue!decwrl!hplabs!hpda!hpcuhb!hpscdc!jackz
From: jackz@hpscdc.HP.COM (Jack Zeiders)
Newsgroups: sci.space
Subject: Re: Supersonic aircraft and noise pollution
Message-ID: <3870008@hpscdc.HP.COM>
Date: 26 Jan 89 21:29:29 GMT
References: <8901240814.AA07708@cmr.icst.nbs.gov>
Organization: Hewlett-Packard, Santa Clara Div.
Lines: 15

> hpscdc:sci.space / roberts@CMR.ICST.NBS.GOV (John Roberts) writes:

>Surely an SR-71 at surveillance altitude doesn't sound too loud from
>the ground - that would spoil the surprise (:-)

	At Beal AFB last fall the SR-71 made a speed run at Mach 3 or so
at altitude. The pilot dumped fuel creating a visible contrail, if he had
not there would be little chance of seeing the aircraft as the altitude 
was reported as 60k feet.  I had a 1000mm lens and could not see the black
aircraft. Perhaps this was because of the ground glass focusing screen.
The sonic 'boom' was a muted pop-pop that could go easily unnoticed if you
were unaware of it.
	At take off the SR-71 is very noisy, The 'A' models apparently 
somewhat more so.
	Jackz