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E-Flite J-3 Cub 25

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Old 02-24-2007, 11:29 PM
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kb3nds
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Default E-Flite J-3 Cub 25

Hello everyone.
I just bought the E-flite J-3 Cub 25 ARF. I am in the process of building it during my free time. I am looking to install a slightly more powerful motor than what E-flite suggests. They want their 25 870kv motor and I would like something just a little more powerful. Anyone put something larger in this plane? Anyone have a suggestion?

Thanks!
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Old 02-26-2007, 12:16 AM
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Default RE: E-Flite J-3 Cub 25

Their Power 32 will work great on a 4S pack

also any 450XT motor or any larger motor around 900-1000kv with a 3S lipo pack


Dan
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Old 02-26-2007, 06:45 PM
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Default RE: E-Flite J-3 Cub 25

I would go with one of the new 25C 3-cell 3700 or the newere 3-cell 30C 3200 mah Li-Poly battery pack. One oif these ultra high output battery packs will give you a sizable increase in RPM and therefore power to the prop. Both PolyQuest, PolyRC, are putting out these packs. I believe that ThunderPower, Hyperion, etc will also have these packs.

Keep in mind that it is the battery that determines the power available. power is measued in Watts which is volts times amps. If you use a 3 cell li-poly and the amp draw is 40 amps you basically have about 480 watts to work with. (12 volts times 40 amps). The higher output of the battery the higher the voltage at load so you get more power to the prop. At this time Korean made Li-Poly cells are the best. The Korean manufactures have good QC and the manuafacturer claims are pretty accurate. I would not say this of Chinese cells.

So, assuminmg you are starting off with a good battery that can supply a good voltage under laod, then you simply need a motor that will supply the correct thrust and prop speed for the J-3 Cub.

We will assume a flying weight of 64 ounces and a typical flying speed of 20-55 MPH. Using a 3-cell 25C Li-poly of 3700 mah

Here is an example:
HiMaxx HC3522-9900 (990Kv)
Prop: 12 x 6 APC E
Amps: 44
Thrust: 74 ounces
Prop speed 47 mph

This is a good example of a motor with more than enough power for the J-3 Cub. There are many others you could choose from. You should get a 15 minute flight time.
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