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Motor weight to power issue. Help?

Old 11-27-2006, 06:51 PM
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JeremySutton
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Default Motor weight to power issue. Help?

Need some advice.

I have a Potensky Eagle (with a Great Planes C-12 ESC and 7 cell 730 maH NIMH). Here's the plane specs:
http://www.rcgroups.com/forums/showthread.php?t=182875

I stripped my pinion gears & busted my prop and am considering the GWS EPS300 replacement recommended by Greg Covey. I have five questions:

1) Can I put the EPS350/gearbox in there at the same ratio of 5.33:1 FOR A LITTLE EXTRA POWER? Specs state the same weight for the 300 and 350 versions?
http://www.gwsus.com/english/product...owersystem.htm

2) Can you explain ratio to me? Would 6:1 ratio provide me with more thrust?

3) Can I reuse my stock 300 brushed motor and attach the GW PINION to it or are the shafts not the same size? Or is it best for me to replace the entire motor with attached? gearbox

4) I want a little more power. It definetly will NOT hover. What size prop do you recommend?

5) Do GWS gearbox packages include the pinion if I reuse my motor?

Jeremy
www.quietflyer.blogspot.com
Old 11-27-2006, 08:37 PM
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Matt Kirsch
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Default RE: Motor weight to power issue. Help?

1) The EPS350 motor is a bit "hotter" than the EPS300. This means that the motor spins at a higher RPM on the same Volts. With the same gear ratio and same prop as the EPS300, you will have more power, at the expense of a higher Amp draw and shorter flight times.
2) A 6:1 ratio, with a bigger prop (IMPORTANT!) will give you more thrust. You need to increase the propeller diameter to compensate for the lower RPMs caused by the higher gear ratio.
3) For the difference in price, get the new motor with the gearbox. Getting the pinion off the old motor and installing the new one is usually not as simple as it looks. They do not come off easy, and they are tough to get pressed back on.
4) You're probably not going to get a good hover out of a brushed motor system no matter what battery and prop you use.
5) and finally: The GWS gearboxes don't usually include a pinion.
Old 11-27-2006, 10:10 PM
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JeremySutton
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Default RE: Motor weight to power issue. Help?

Thank you Matt.

The plastic pinion I have on will be very easy for me to remove, but the new pinion, it sounds, will be a challenge to put on?

It sounds like the 6:1 ratio may be the way to go. Do you recommend the ESC300 or ESC350? Do you think I could maintain 5 minute flights on my current batt -- 730 mAH 7 cell NIMH?

I have also seen e-Flight has a 370, but I don't know about the weight on that one.

If I go 6:1, what prop size do you recommend?

Jeremy
Old 11-27-2006, 10:16 PM
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JeremySutton
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Default RE: Motor weight to power issue. Help?

Matt,

Will my Great Planes C-12 ESC have any problem handing a 350 sized motor?

Would this motor/gear work:
http://www.wholesaletrains.com/Detail.asp?ID=200412949

Or would it be best to stick with the GWS 350 set up? The GWS looks easy to install according to Greg Covey's review.

Jeremy

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