On Tue, 23 Nov 2010 16:18:44 -0800, pyotr filipivich
wrote:

Gunner Asch on Sat, 13 Nov 2010 19:46:51 -0800
typed in rec.crafts.metalworking the following:

Yawn. You need another layer of foil on your beanie.

Impulse Synthetic Aperture Radar (ImpSAR)
http://www.cambridgeconsultants.com/prism_200.html

Actually..even the chicoms are making them.....

http://hawksoptic.en.ec21.com/SuperV...1_3364187.html

Then there is IR thermography...

http://www.youtube.com/watch?v=KsbsCWu0s6Y&feature=fvw

http://www.youtube.com/watch?v=BzHCD...eature=related

I've read some comments to the effect that you can use "space
blankets" to counter some of the "thermal" sights reading your
location through walls.
Does anyone have any serious information, not just "seems like it
would work to me." on the effectiveness? After all, I got an email
some years ago saying that safest place to be in an earthquake was not
in a doorway, but in the "triangles" formed by furniture and walls.
Well, "that sounds like it would work." Only it isn't. (Logic is
the means to reach a wrong choice with confidence.)

tschus
pyotr

The principle behind "space blankets" is that they reflect and contain
IR. They offer essentially no conductive insulation. IR that is
contained by reflection is not available to external sensors.

Schjeldahl in Northfield MN made a kapton film with a few microns of
gold on it that was even more effective. If you draped a bit of it
over the back of your hand, it felt hot. Essentially NO infrared got
thru it.

I still have a cheap Frabil styrofoam minnow bucket that I wrapped in
the Schjeldahl film and put the whole works in a plastic paint pail.
It keeps minnows cool and frisky for hours even on a hot day in direct
sun. I had the film left over from a research project at work.

On Thu, 25 Nov 2010 00:18:50 -0600, Don Foreman
wrote:

On Tue, 23 Nov 2010 16:18:44 -0800, pyotr filipivich
wrote:

Gunner Asch on Sat, 13 Nov 2010 19:46:51 -0800
typed in rec.crafts.metalworking the following:

Yawn. You need another layer of foil on your beanie.

Impulse Synthetic Aperture Radar (ImpSAR)
http://www.cambridgeconsultants.com/prism_200.html

Actually..even the chicoms are making them.....

http://hawksoptic.en.ec21.com/SuperV...1_3364187.html

Then there is IR thermography...

http://www.youtube.com/watch?v=KsbsCWu0s6Y&feature=fvw

http://www.youtube.com/watch?v=BzHCD...eature=related

I've read some comments to the effect that you can use "space
blankets" to counter some of the "thermal" sights reading your
location through walls.
Does anyone have any serious information, not just "seems like it
would work to me." on the effectiveness? After all, I got an email
some years ago saying that safest place to be in an earthquake was not
in a doorway, but in the "triangles" formed by furniture and walls.
Well, "that sounds like it would work." Only it isn't. (Logic is
the means to reach a wrong choice with confidence.)

tschus
pyotr

The principle behind "space blankets" is that they reflect and contain
IR. They offer essentially no conductive insulation. IR that is
contained by reflection is not available to external sensors.

Schjeldahl in Northfield MN made a kapton film with a few microns of
gold on it that was even more effective. If you draped a bit of it
over the back of your hand, it felt hot. Essentially NO infrared got
thru it.

Multiple layers of extremely thin aluminized (or gold coated) film
work really well. 450 degrees F difference in an inch or so with
almost no heat loss. Used on spacecraft, cryostats etc.

On Nov 25, 9:53*am, Spehro Pefhany
wrote:
...
Multiple layers of extremely thin aluminized (or gold coated) film
work really well. 450 degrees F difference in an inch or so with
almost no heat loss. Used on spacecraft, cryostats etc.

Jack Stephenson experimented with the idea, and sold me the polyester
film for my insulating window inserts:
http://www.oregonphotos.com/Warmlite1.html
The Filmgap tent was insulated with many layers of metallized Mylar,
making a down bag unnecessary. IIRC he said he couldn't bond or glue
it well enough.

Those tents are super light and withstand storms very well. The one I
have weighs under 3 Lbs and is supposedly good for 100MPH, above that
he says the end straps tear out. At 40 - 50MPH it doesn't even flap.
However the poles are fragile if point-loaded by a tight cargo strap
etc.

jsw