Dandy, but 3 phase isn't practical for me.
http://www.allproducts.com/tami/chuanfan/05-pf.html
http://www.kooltronic.com/b-blower/hprad/hprad.htm
cute animation:
http://www.rtpumps.com/rtpumps/web/h...256EE5007976A9
I'm going to pursue the multiple blower configuration:
1-easier DC control (turn some on/off)
2-variable voltage of an EBM-Papst (spec'd at 24 volts) can be from 9 volts to 32 (much "play" room)
3-should be cheaper than a specialty unit (unless I can get lucky on eBay, as you did).
I'm assuming, for now, that running a pair side-by-side isn't going to be an issue.