Need help with geared Mag. Mayhem set up - RC Groups
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Aug 03, 2001, 01:45 AM
Flying slowly along..

Need help with geared Mag. Mayhem set up

I'm trying to set up a magnetic mayhem to power a Flying wing. I currently have an 3.8:1 MP Jet Planetary GB that I would like to use with a Magnetic Mayhem motor that I also have. I would like to use this setup with 8-10 cell packs (prefer 8 cells). I would like to keep amp draw at about 20 amps.

What prop size would be optimum for good speed and better vertical then I currently have with my direct drive Turbo 450? Would I be better off running the setup direct? If so, any prop recommendations?

Please excuse my lack of knowledge on the subject, I'm just starting to learn about geared setups, and higher powered motors. Thanks for the help guys.---Rob
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Aug 03, 2001, 03:06 AM
Speed Demon
GregG's Avatar
Hey Rob, I just ran all the figures on your Zagi through Motocalc with the 8-1400Ae pack and 3.8/1 geared MM motor. I had to go up to a 12 X 10 prop to pull 17 amps out. That gives you 82 watts/lb. Now, if you go up to 12 cells still using the 1400Ae's and switch out to a 10 X 8, the motor is running at ~27,700 RPM which isn't too bad. The ampdraw is still only 17.2 amps but you bump up the watt/lb rating to 107. Your prop pitch speed isn't past 50 MPH, I think thats a bit slower than you wanted. If it were me, I'd go with a smaller GB ratio. Just for kicks, I ran it through with a 2.5/1 GB and a 9 X 7 prop, still 12 cells. The prop speed was 65 MPH and the watts/lb were up to 133. It's been said that around 120 watts/lb will give you true vertical. You'll have to try it out and see. Keep up the good work Rob, I like it when someone isn't afraid to try something new.
Aug 03, 2001, 09:32 AM
Registered User
Andy W's Avatar
A very big prop will be needed. If you're only running 20A, why move from the lighter, more compact 450? Why not just put a GB on it (although you'll still need a huge prop)..
Aug 03, 2001, 04:15 PM
Flying slowly along..
Hmmmm direct drive might be the answer. Do you guys think I can get away with 10 cells on the T450?---Rob
Aug 03, 2001, 11:58 PM
Registered User
Andy W's Avatar
I say sure, as long as you keep the power around 180W max..