Path: utzoo!mnetor!uunet!husc6!cca!g-rh
From: g-rh@cca.CCA.COM (Richard Harter)
Newsgroups: sci.misc
Subject: Re: Daylight precision bombing in WW II
Message-ID: <22677@cca.CCA.COM>
Date: 23 Dec 87 19:14:11 GMT
References: <317@uhmanoa.UUCP> <19253@linus.UUCP> <16999@topaz.rutgers.edu> <1594@brahma.cs.hw.ac.uk> <2576@calmasd.GE.COM>
Reply-To: g-rh@CCA.CCA.COM.UUCP (Richard Harter)
Organization: Computer Corp. of America, Cambridge, MA
Lines: 39
Summary: Tracking seagulls for fun and breakfast

Adrian Hurt:

Incidentally, how good is radar against non-metallic targets?

Johmn Pantone:
>
>Radar (at least the radar used by police to detect speeders) can detect
>non-metallic objects quite well.  I have had the opportunity to test them
>against a number of substances, and know the results to be true.  The best
>reflectors were (non-metallic):
>Fiberglass, plywood (especially marine), doped canvas (like airplanes) and
>solid hardwoods (oak and maple).  Soft wood was less reflective (like balsa)
>but was not at all invisible.  Interestingly enough, people were relatively
>good reflectors - especially if you cought them going straight towards or
>away from you (chests and backs); I speculate that meat has enough
>water/density to reflect well.

Back (many years ago) when I was working on the Atlantic missile range as
a radar technician we used to routinely track seagulls.  I don't remember
the maximum range at which we could track them -- I know it was more than
20 miles but I don't remember if it was as much as a 100.

Trees are reasonably good reflectors, particularly for side scanning radars.
A tree will have a radar cross section as large as a truck.

When you are talking about visibility to radar geometry is very important.
Most of the return from an object is from corners.  I.e. the beam hits a
surface, bounces off the surface to a second surface at right angles to the
first, and comes back to the origin.  If you look at the detailed reflection
pattern from a vehicle you will see that most of the return comes hot spots
created by the local geometry.  An example of hard to detect geometry is a
sphere -- the only visible point is the spot directly closest to you.  One
of the important tricks in the stealth game is to make sure that the plane
has a good geometry.
-- 

In the fields of Hell where the grass grows high
Are the graves of dreams allowed to die.
	Richard Harter, SMDS  Inc.