3w LED Spacing required for passive cooling on Aluminum flat Sheet?

[FailBoat]

I'm making a 36 watt (3wx12 LED) figured I'd try spacing out the LED and have them passively cool.

Anyone know how much spacing I would need?

Would a sheet like so: https://www.menards.com/main/tools-...tal/aluminum-sheet-6-x-18-x-025/p-1466180.htm work? If I did the math right I could do them 3" apart.


*It's going have "some" air flow (a computer fan) but lets say it fails*

 

[Steviodaddio]

Place heatsinks on the other side of the aluminum, even if it's small. Realistically I think 3" apart is overkill when you could probably get them an inch or so together. HeatSinksUSA has plenty of small heat sinks you can get for dirt cheap. Or go to a computer shop and ask for all the old CPU or graphic card heat sinks.

I would also put a few fans, at least 2 or 3. Depending on how you are running it if you can get one or two to pull cool air from the top and then one or two to vent then you should be all good.