Fan design ideas

[Jonsio]

just wanna know if anybody has attempted to design 80mm, 92mm or 120mm fans to look like 3-blade electric fans (home appliance) or airplane propellers or chopper rotors (2 or 3 blade)? why not, since in actual usage these 'fan' types move a lot of air. maybe at low RPMs they are silent and at same time move lots of air compared to conventional designs... :beer:

 

[mroleg]

I think thermaltake has a 3 blade fan.

 

[Jeff7]

I would expect that if it was better, it would have been done by now.
One thing I can think of is that airplanes and AC-powered room fans have motors that can produce a lot of torque. Computer fans are low-power; I don't think that they can produce the torque needed to efficiently move a 3-blade prop. Of course, that said, there are some - I've used one already, a Beta Nidec 12VDC fan with three blades. It moves a lot of air for its size. And it is probably about 55dB too - it's rather loud, definitely not something I'd want in a computer next to me.

Ah, found the link for the place where I got the fan a few years ago; and they still have them in stock.
130CFM, 53dB. My 55dB thing above was just a guess too. 800mA rating too - it's got pretty good current draw, so it does have some torque behind it. Notice then that this 9-blade fan only draws 120mA.