Cooling Fan aerodynamics.
 

Just stumbled on this,
Davies Craig radiator fans, scroll down to the bottom of the page they have a little discussion of curved vs straight blades, tripping the boundary layer and using winglets on the ends of the blades vs solid ring to reduce drag from tip vortexes.
Thermatic Electric Fans

So, if I have this correct, this replaces the current fan(s) your vehicle has and since it is a more efficient fan from the straight blades, it uses less engine power, therefore increasing FE? What about if your vehicle has a grill block, will it still be worth it? Would these work horizontally, rather than vertically like most RAD fans?

On a side note, what is the difference between a pusher and puller application?

Thanks,
Jeff

I don't think you would see a payback in your lifetime, but if you were designing from ground up then you might look at them for high efficiency or in competition conditions.
Their fans are good, but expensive, for most of us if we pay attention to the details of the grille block and radiator airflow, any fan is only minimally required.

I have been running for 2 years without a fan at all, my travel is mostly hwy, but I am planning to do a small electric fan just for those stop/start traffic conditions.

I'm pretty sure they can be mounted horizontally as well as they are also used for top mounted aftercoolers on turbodiesel's.

Pusher fans are mounted infront of radiator, pullers behind, generally the pulling function is more effective, most just reverse direction of rotation but this causes a drop in efficiency because the fan blades are going backwards, ideally you get a fan for the correct application.