Heat insulation

I'm almost finished fabricating my robot's protection shell. It is made of polycarbonate (4mm walls, 6mm roof). The robot is a rover meant to operate on rought terrain (desert is
definitely a possibility), and I believe direct sunlight on electronic components may be harmfull.
I'm thinking about applying some kind of film on the polycarbonate to block sun light. What do you think?
The robot will have two input fans and one output fan to help circulate fresh air inside the protection shell, as seen below
http://www.merlotti.com/EngHome/rover/protshell%20-%20schematics%20-%20revA.jpg
Thanks
Padu
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You could bond mylar to the inside of the polycarbonate to eliminate almost all radiative heating from the sun, but it will heat the polycarbonate up as the rays pass through it twice, or UV is absorbed in the process. this could (and probably will) heat the 'bot up through conductive means. If you put the mylar on the outside it will avoid heating the shell but could suystain alot of nicks and scuffs, possibly tears.
You could try getting a roll of window tinting material, either mirrored or unmirrored. It's sort of durable (relatively), pretty cheap, and pretty easy to apply. With the "glue" already on it, it could save a step in the process as well. It's UV stable, and often UV reflective which will be the predominating factor in parts degredation aside from heat.
Another possibility would be to use a UV stable and thermally reflective lexan. Tougher than nails and since the protective measures are built in, you dont have to worry about them degradng over time. It's more expensive though and you do already have the shell your currently using, so that may not be a viable option.
--Andy P
Padu wrote:

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"Andy P" <snipped>

heat. ...
That's what I've ended up doing. I bought a reflective film to put on top and a dark one for the walls. This way I could install some status LED's inside the protective case and still see them from the outside if I wanted. Not sure if they will be visible enought under direct sunlight though.
Padu
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shiny white enamel.
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Padu wrote:

What Jim said... just paint the thing white. If you use a paint with solvent the pigment will penetrate into the plastic, so it won't scratch off. Krylon makes some called Fusion that is specifically designed for plastics, using an organic solvent (toluene) that reacts with the plastic. Any of the Testors model paints that contain toluene will also work, though the cans only have 3 ounces of paint material in them. They're excellent paints, though a bit pricey.
Don't worry about the sun heating the plastic. Polycarbonate has a melting point of over 350 dgrees.
-- Gordon
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electronic
to
20-%20
Cover it with mirrors.
Joe
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Glass mirrors? This is an outdoor robot, remember. Even if he uses mirrored acrylic that's a lot of extra weight.
-- Gordon
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Yeah, it would weigh a lot, but man it would look cool with the sun shooting off of it.
Dontcha think?
Joe
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wrote:

if it's in the states you run it i'm sure there's lots of people willing to sue your pants off for temporarily blinding them while flying their corporate jet(toy), even if it causes no damage. but yeah, it'd look spectacular. besides white paint, i suggest a big parasol made from solar panels.
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wrote:

Oh, I'm not afraid of any lawsuit.
I should have thought about the solar panels first though.
Eventually I'd like to build somehting bigger than a BEAM bug that is solar powered.
Joe
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Gordon McComb wrote:

How about aluminum cooking foil, shiny side out? Weight-penalty close to zero; nice, smooth application not necessary, since specular reflection not essential....I seem to remember that you could get the stuff with an adhesive backing, too...but for initial trials just use the ordinary household stuff...just be careful to keep it away from shorting any electrics...
Geoff.
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Might be a problem with heat transfer through the foil, maybe with mirrors also?
Side note : I always use the shiny side out when I wrap myself with foil. This ensures that the government agents cannot hear my thoughts.
Joe
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