Non-Urgently Off Topic

[Will]

Every ceiling fan I've ever seen has used simple "paddles" for blades. The cross section of the blades, in other words, is perfectly flat, and doesn't resemble a wing or a propeller. It must simply move the air around by Newtonian mechanics, without taking advantage of Bernoullian geometries.

Question: is there any advantage to be had in putting airfoils on ceiling fans?  Making them look like big propellers, in other words?  More cool air for less electricity, perhaps?  On the other hand, the fan's job is to move air around, not glide through it efficiently.  With that in mind, would airfoils possibly reduce the benefit of a ceiling fan, i.e. making it a more efficient machine, but one that doesn't cool the room enough?

Will

[Tom]

Hi Will,

Seems to me increasing angle of attack near the spinner should increase air volume, and might require more horsepower and thus a fan becomes less "green". I don't know how much more power it would consume though. Maybe we think about fan "accessories" (implement the "Bedini Motor" theory http://www.youtube.com/watch?v=g9ARja0DiT0 for max green effect).

On really warm days you might end up blowing more hot air around, which does not help with cooling.

I like the portable tower fans; a cylinder rotates inside a tall column and forces air out, kind of like a turbine. Same issue though, I guess the trick is to make the temperature go down on really hot days. Go to the beach, turn on AC, or climb up several thousand feet. (in my neck of the woods, dosen't always work as sometimes its warmer at 4000FT than at ground level).