Simple. The shelter consists of two hemispherical shells of nylon, one inside the other, to form a double-walled dome. The two shells are joined at the bottom, so the inter-wall cavity is a closed space, apart from a nozzle.

Also included is a man-sized can of fire-rated polyurethane foam (low density, high expansion, fast curing).

In an emergency, the foam is released into the cavity between the walls, creating a six-inch-thick hemisphere large enough for two or three people to hunker down for the time it takes the wildfire to pass.

This is about the lightest fireproof, heatproof structure I can think of.
-- MaxwellBuchanan, Aug 22 2015

Yea, maybe. It's certainly insulation.

If you puff it up in a big sphere you could put a little distance between you and the flames which couldn't hurt. Maybe have the foam inflate a double walled balloon/tent type deal.
-- doctorremulac3, Aug 22 2015


//Maybe have the foam inflate a double walled balloon/tent type deal.//

You mean, a bit like the thing I described explicitly in the idea? Or not?
-- MaxwellBuchanan, Aug 22 2015


Were you talking about it expanding like a balloon? I thought you were suggesting a solid structure into which you shot the foam. My oops.
-- doctorremulac3, Aug 22 2015


hmmm

I like it. (+)

I'm picturing what may be a lighter alternative though.
Two collapsible, geodesic, spring-loaded aerogel hemispheres.
The weight would be negligible. Both hemispherical shapes could be reduced in size by configuring the triangular panels to fold up on themselves, and the weight of the canisters of liquid foam would be unnecessary.
-- 2 fries shy of a happy meal, Aug 22 2015


The hemispherical form factor is a bit pedestrian, isn't it? Surely what's wanted is the full 360 degree fire-retardant zorb, which the occupants could ride triumphantly through the fire-front, on to the burnt out area beyond. Some practice drills may be required.
-- pertinax, Aug 23 2015


//Were you talking about it expanding like a balloon?// Ah - my bad. I meant a purely hollow fabric shell which is inflated by the foam.

The unfilled shelter would basically be a sphere made of nylon, but with one side "caved in" to create a double-walled hemisphere. There would be ties connecting the inner and outer walls. The whole thing has no rigid parts, so it can be scrunched up into a small package, pending inflation by the foam.

//Two collapsible, geodesic, spring-loaded aerogel hemispheres.// The spring loaded structure will not be as light or compact as a fabric shell plus foam canister. Also, the geodesic panels would have to be quite thin so, at best, you'll have an inch of aerogel and an air-gap between you and eternity.
-- MaxwellBuchanan, Aug 23 2015


Yea, you don't have a big weight allotment to play around with here. You've got a firefighter who's already probably carrying 30 pounds of equipment around on uneven even mountainous terrain.

It really comes down to a protection from x amount of heat for y amount of time per pound thing.
-- doctorremulac3, Aug 23 2015



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