Zik, > Due to the constraint of having to make the thing aerodynamic for forward > flight I'm using multiple smaller sized ducted fans for vertical mode. The > downside is that they're less efficient than a larger fan would be. What is the diameter and pitch of this fan? If that is 6" then I think it's round 18k rpm (without doing the maths) and the prop reach the speed of sound - which means less efficient than it at that speed plus very noisy. As far as I remember that size of fan was driven with a 400 brussless outrunner without a problem using around 12V@15A at max. That made around 15k prm. Anyway, that fan looks a high pitch prop made for fast forward flying, and a low pitch prop with a higher diameter would give you a better statical thrust in my opinion. Have you ever considered of helicopters? They are fairly good at hovering and efficient on forwad flying as well :-) Tamas On Tue, Jul 8, 2008 at 7:08 AM, Zik Saleeba wrote: > On Tue, Jul 8, 2008 at 4:14 AM, Sean Breheny wrote: > > > 1) 4.6kW seems like a LOT of power to produce 6kg of thrust. > > > Due to the constraint of having to make the thing aerodynamic for forward > flight I'm using multiple smaller sized ducted fans for vertical mode. The > downside is that they're less efficient than a larger fan would be. They're > only used for a few seconds at takeoff and landing and then the plane > transitions to more efficient forward flight using wings for lift. > > 2) Can your battery pack really supply 210A? How long do you expect to > > pull 210A for? > > > Here's a web page with some info: > > http://www.rctoys.com/rc-toys-and-parts/TP-9000-6S2PX/RC-PARTS-THUNDER-POWER-6-CELL-LITHIUM-BATTERIES.html > > It's meant to handle 180A continuous or 400+A burst. In practice I'd be > using ~210A for a few seconds at takeoff and landing and flying at ~10A the > rest of the time. > > Cheers, > Zik > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- Rudonix DoubleSaver http://www.rudonix.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist