MEDELMA@CMS.CC.WAYNE.EDU (Michael Edelman) (02/07/91)
From: Michael Edelman <MEDELMA@CMS.CC.WAYNE.EDU>
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A few items collected while Karl was away:
1. Ejection seats. A friend worked on B-52 ejection seats during the
Vietnam era when it was discovered that a great majority of a B-52 crew
who ejected suffered a back injury that disqualified them from further
service. My friend left the project before it was completed, but I assume
some changes were eventually made.
2. Stealth & radar: As regards the theory that the planar surfaces of
the F-117 providing "sparklies" that are supressed as noise- I ran this
by a friend who does radar research and design at one of the country's
leading radar labs, and he said "livestock refuse", or words to that
effect. The real reason for the planar design seems to be one of the technology
limitations at the time the craft was designed. The B-2, being a later design,
was able to use profiles the F-117 could opnly approximate. This last bit
isn't from my radar designing friend, but from one of the aircraft enthusiast
magazines of last fall. Sorry, can't recall the citation.
An Australian group claimed they had a low frequency radar that could spot
a stealth craft, so I ran this idea past my radar expert friend. It's an
old idea, it seems. The idea was to excite the entire aircraft structure
by using wavelengths corresponding to the size of the craft- i.e., make the
entire craft resonate as an antenna.
The problem is that the airframe has an extremely low Q- that is, it's
very broadly tuned and doesn't have any sharp resonances, and hence no
strong radar returns. Even if you could get a strong return at, say, 10MHz,
you'd be dealing with 30 meter wavelength, which means low resolution and
correspondingly large antennas with low gain and poor directionality. They'd
be extremely easy to spoof with a little active electronics, assuming they
gave any information other than "there's something out there somewhere,
either an aircraft or maybe a cloud..."
There has also been some work done with extremely broadbanded radar, which
is something akin to the swept-frequency radar that Thom speculated about.
The primary feature is jam-proofing, though, as you can transmit over a
wide range but listen where jamming is least effective. The transmitters
are basically spark transmitters, which means we havn't come *that* far in
the last 100 years :)
--mike edelman medelma@cms.cc.wayne.edu medelma@waynest
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