Orion and Malcom - you guys are having a simply facinating discussion over in the Bonded Metal Construction thread, and something you just talked about brought back a memory of an idea I once had.
I attended the WesCon (or was it WestCon?) manufacturing show a number of times back in the 'eighties, and one time in particular I came away with some samples of a reticulated aluminum foam in various densities. I think I had one in silicon carbide as well. Seems like they could make the stuff out of almost anything, and it was machinable almost like it was solid.
I was in my foolish youth (as opposed to my foolish middle-age), and was tinkering with the thought of designing a racing airplane with a liquid cooled engine. I was thinking of flush-surface radiators in the (forgive me, Orion) canard. In fact, my idea was that the entire (structural) skin of the canard would be an aluminum sandwich with machined reticulated aluminum foam cores dip-brazed to aluminum facing sheets. Seal the edges, plumb the thing into the cooling system for the engine so the coolant passed through the foam core - and violá, zero cooling drag. I realized there'd be quite a bit of pressure loss through the foam, but I figured the weight penalty of a larger pump wasn't much of an issue in a racer. You'd need to pass a little bit of air through the interior of the flying surface so the temperature (and therefore air pressure) increase wouldn't burst the structure, but that again seemed a small price to pay.
There's no way I could ever capitalize the idea - it'd be a hideously expensive structure - but I've always wondered if it would've worked. Any thoughts?
I attended the WesCon (or was it WestCon?) manufacturing show a number of times back in the 'eighties, and one time in particular I came away with some samples of a reticulated aluminum foam in various densities. I think I had one in silicon carbide as well. Seems like they could make the stuff out of almost anything, and it was machinable almost like it was solid.
I was in my foolish youth (as opposed to my foolish middle-age), and was tinkering with the thought of designing a racing airplane with a liquid cooled engine. I was thinking of flush-surface radiators in the (forgive me, Orion) canard. In fact, my idea was that the entire (structural) skin of the canard would be an aluminum sandwich with machined reticulated aluminum foam cores dip-brazed to aluminum facing sheets. Seal the edges, plumb the thing into the cooling system for the engine so the coolant passed through the foam core - and violá, zero cooling drag. I realized there'd be quite a bit of pressure loss through the foam, but I figured the weight penalty of a larger pump wasn't much of an issue in a racer. You'd need to pass a little bit of air through the interior of the flying surface so the temperature (and therefore air pressure) increase wouldn't burst the structure, but that again seemed a small price to pay.
There's no way I could ever capitalize the idea - it'd be a hideously expensive structure - but I've always wondered if it would've worked. Any thoughts?
