REFLECTOR: updraft cooling

[Douglas Holub]

I can understand why Burt Rutan and Nat Puffer are proponents of updraft cooling. From an engineering point of view, it has a lot going for it. You need more cooling when the airplane is climbing. If the cooling intake is below the wing, the pressure is higher during a climb so you automatically get more cooling during a climb. Similarly, it would be nice if cooling was minimized during descent. The pressure is reduced under the wing during descent, and so there is less cooling to the engine. Also, you've got convection working with you instead of against you with an updraft system.

That all adds up to more drag with down draft cooling, because the NACA scoops have to be large enough so that there is adequate cooling during climb out, when the pressure at the NACAs is at its minimum.

But the down draft is a lot simpler to implement, and that's probably going to be the deciding factor for me.

Doug Holub
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