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Outrunner For Goldberg Electra

Old 02-10-2015, 05:14 PM
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blue53
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Default Outrunner For Goldberg Electra

I'm new to the electric side of RC. I have an older Goldberg Electra. Looks like an electric version of the Gentle Lady. It does not have the original motor. Looking for some help on what size motor/ESC and Lipo's.
Thanks

Lee
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Old 02-10-2015, 06:15 PM
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fhhuber
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Electra is a reinforced Gentle Lady. The reinforcements are intended to deal with the heavy 6 cell Sub C NiCd it expected to be used with the brushed can motor (which was about as good as e-flying got in the early 1980's)

Turngy 2830 will outperform the original can motor and is far lighter. Be sure to get the LOW kv version and use an APC folding prop (10X5) for best results.

Use 3S 2200 mah LiPo for more than 200% of the energy capacity of the original NiCd at less than half the weight.

I recommend mini or micro servos. 20 in-oz is plenty for the aircraft. Again saving weight vs the original version's use of "standard" appx 42-47 in-os servos.

If you switch to a Gentle Lady wing you can come out very close to the weight to the unpowered Gentle Lady with this setup.

Note that the brushless motor is far smaller than the original can motor and you should move the firewall forward. letting you push the battery into the compartment forward of the wing instead of in the OEM battery bay.
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Old 02-10-2015, 06:20 PM
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blue53
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Thanks for the info. I have been trying to figure this stuff out. Looking for some form of conversion chart that would show some form of a reference in converting Nitro to electric. ( understanding that nothing is a given in comparing the two but can give you an idea.) I have a couple of nitro planes I'm thinking about changing over as well.
Also, should I be concerned over the number of turns.
Thanks
Lee
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Old 02-10-2015, 06:46 PM
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fhhuber
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Best way to compare glow to electric is to find an electric motor that will turn the same prop the same rpm and find out the watts of the motor.

A typical .46 turns a 10X6 about 13000 rpm on 10% nitro.

Find a motor that has kV = 13000/(nominal pack voltage * 0.8) and is rated for a 10X6 prop.
Or as close as reasonably practical.

The 0.8 is the expected reduction in rpm vs theoretical due to maximum safe load.
kV is the rpm the motor will turn per volt applied if there is no load
(not even the friction of the motor's own bearings)
No motor actually turns at its kV * volts applied... ever.
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Old 02-10-2015, 06:48 PM
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blue53
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Thanks for all of your help.

Lee
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