stunthanger.com
Electric Stunt => Gettin all AMP'ed up! => Topic started by: frank carlisle on December 02, 2006, 02:17:43 PM
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I'll be using Dick Sarpolus plans (modified for in line props) for a Fokker D-23-a foam Nobler wing- and an Axi 2826-10 motor and Poli-quest 3700 mah 2C battery.
What do you think an appropriate prop size would be? Front and back.
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Hi Frank,
Are you ganging the two on a common shaft?
Counter-rotating? it actually matters.
If they were closely coupled counter-rotators, then the diameter would be almost exactly the same.
Put them far apart, and the diameters would need to be maybe 87% of a single prop.
why? power is proportional to diamter ^5 for all other things equal, so 1/2 power absorbed is 87% diameter.
If they don't counter-rotate, I have no idea, especially as the effective pitch of the back prop will be reduced by the spiral airflow from the front one.
for what little it helps,
Dean
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Dean,
I'm putting the on a common shaft. The distance is 22" from prop tp prop. They'll be rotating in the sme diction. One tractor-one push.
Axi 282610. 3700mah 3c.
Efficiency in this case isn't as important to me as efficacy.(big word hope I used it right).
Sport model , twin boom with Nobler wing.
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Frank is such a trend setter. For general flying, it may not be an issue, but if you wanted to get a stunt run out of the deal, would there be enough battery on board to swing 2 props for that long?
Additionally, on a common shaft, would you want to offset the props so that they appear as 4 blades when viewed from the front or rear or would lining them up be better?
So many things to think about.
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You've already seen the electric Smoothie go John.
I'm thinking this one would be a sport model.
And yes I think the AXi could turn two props. Same difference as putting a downsize 4 blade prop on where a 2 blade prop was.
Jan will be making bearings , shaft and couplings.