Mark Borgerson wrote:
In article %AMfg.1638$I61.24@clgrps13,
says...

wrote:

Ken Chaddock wrote:



Block 1B CIWS has an infrared and optical tracker that would do nicely
against any UAV within it's range...the question is finding the UAV in
the first place. An Infrared search system with the ability to designate
to a B1B Phalanx would work quite well I think...


But a prop-driven UAV with a small engine and some attention to exhaust
masking would not be an easy IR target.

If all you want to do is locate and identify a ship, and beam an
illuminating laser at it to guide the incoming ordnance, then the UAV
can be very small and very hard to detect.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk

Have you ever seen the radar return from a prop ? Looks like a bloody
747...a prop-job wouldn't be a particular problem and contrary to
popular misconception, most modern IR trackers don't rely on a hugh heat
gradient but rather on the difference in emissivity between the target
and the background, IOW it's tracking the delta, not the absolute IR
output of the target...


So what IS the radar return from a wooden or fiberglass propellor like?

Not as strong as from metal but still there and the main feature of the
return is the doppler...which is unique and quite distinctive since it
varies from hub (near zero doppler) to quite high since the prop tip is
almost certainly supersonic. Remember Mark, you do get a radar return
from wood and fiberglass

Fundamentals of Stealth Design

The following article was written by Alan Brown, who retired as Director
of Engineering at Lockheed Corporate Headquarters in 1991. He is
generally regarded as one of the 'founding fathers' of stealth, or low
observable technology. He served for several years as director of low
observables technology at Lockheed Aeronautical Systems Co. in Marietta,
Ga. From 1978 to 1982, he was the program manager and chief engineer for
the F-117 stealth fighter and had been active in stealth programs since
1975. This article first appeared in 1992. Design for low observability,
and specifically for low radar cross section (RCS), began almost as soon
as radar was invented. The predominantly wooden deHavilland Mosquito was
one of the first aircraft to be designed with this capability in mind.
Against World War II radar systems, that approach was fairly successful,
but it would not be appropriate today. First, wood and, by extension,
composite materials, are not transparent to radar, although they may be
less reflective than metal; and second, the degree to which they are
transparent merely amplifies the components that are normally hidden by
the outer skin. These include engines, fuel, avionics packages,
electrical and hydraulic circuits, and people.

The UAVs that I've seen and the powered paragliders don't have metal
propellors. I suspect the reason is economics, rather than stealth,
though.

I'm absolutely positive...

....Ken