John in CR said:knighty said:you can fit them pointing in opposite directions on each side, so one side sucks and the other side blows
and/or, google a vented brake disk... you could use somehting like that for the 'out' side if you have enough room... so you could push air in at the outside edge with the blades, and then suck it out from the center of the opposite side ?
Impossible. No fan on the planet works like that, because air won't fight against centrifugal force.
Yup, youd need an unbalanced force applied to the air to make it move in a linear form. matching of forces will cause circulation not venting.