On Tue, Jul 8, 2008 at 5:25 PM, Tamas Rudnai wrote: > What is the diameter and pitch of this fan? For this prototype it's three off-the-shelf 96mm fans running at up to 40,000 rpm. Here are the details: http://oos.modelengines.com.au/command/servlet/Command?command=display_item_pub&pkey=meng&f_id=[INVALID%20FORM%20VAR]&itemid=HIBMB36-34-1850 http://oos.modelengines.com.au/command/servlet/Command?command=display_item_pub&pkey=meng&f_id=[INVALID%20FORM%20VAR]&itemid=HIM-DF96 They're not really ideal for this application but they're good enough for a quick prototype. If the prototype is successful I might consider fabricating some purpose-built ducted fans. Have you ever considered of helicopters? They are > fairly good at hovering and efficient on forwad flying as well :-) Helicopters aren't nearly efficient enough in forward flight for my application (aerial survey). I don't have much of a choice about takeoff/landing locations hence the VTOL requirement - yet I need as much flight duration as possible to take as many photos as possible, hence the preference for a winged craft. Cheers, Zik -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist