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clarence Regular Member Joined: 27/10/2006 Location: Posts: 63
Posted: 10:27am 03 Apr 2007
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hi all, I havn't posted for a while, I built a 7 phase neo brake drum f&p some time ago and it cogged quite badly relative to original standard magnet drum 3 phase motors. I have finally got a 3 blade prop 2.8 metre diametre fitted. [200 mm diam pvc pipe blades].
the wind today was at best 20kmph, and the thing starts very easily to my surprise, and spins like crazy with no load, but with a 12 amp load it is struggling to do 50 rpm even in gusts.
so I am inclined to think that in order to get any real power out of my thing, at least a 2.5 metre diametre 3 blade prop, or 3 metre 2 blade prop is needed, and 25kmph plus winds. this thing starts in about 10kmph winds quite easily cogging simply is not an issue.
my blades are probably not terribly efficient, but they certainly start easily.
I think from now on I wont be too concerned with cogging, and concentrate on bigger blades.