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Great Planes J-3 Cub .40 Size with a .75AX?

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Great Planes J-3 Cub .40 Size with a .75AX?

Old 01-15-2017, 03:35 PM
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PaulWa11
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Default Great Planes J-3 Cub .40 Size with a .75AX?

The recommended engine size for a 2 stroke is .40 - .61 - Just happen to have a brand new OS .75AX Anyone tried this in a cub his size?

wondering if its to big or if i can make it work?
Old 01-15-2017, 04:08 PM
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J330
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Although it's not impossible to do it, why add to the stresses on the plane, having ground clearance issues to overcome perhaps, and other compromises to avoid the ideal choice?

The .61 is a 4 stroke recommendation, the .40 is the 2 stroke.
The plane is not designed for a .75 2 stroke.
You can save that engine for another application, or perhaps sell it to get the engine you need that would be suitable.
26.5 oz of the AX .75 as well as a 14" to 15" prop recommendation, neither suit that model as it was designed. The wingspan and flat bottom airfoil of the cub sure will test the structure to it's limits and beyond, if you choose to run wide open throttle or high pitch props.
Some put V8 engines in motorcycles. Doesn't mean it rides very well in all conditions.
Neither will the Cub with a .75.
Old 01-15-2017, 09:09 PM
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PaulWa11
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Your absolutely right, i just happen to have the .75 for a CG 300 project thats not close to completion yet - guess just excite to break it in. Time to find a nice 4 stroke then
Old 01-16-2017, 06:41 PM
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jester_s1
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I have that size Cub with a .72 4 stroke. It's the perfect engine IMO. It flies scalelike with enough reserve power for mild aerobatics.
Old 01-18-2017, 08:31 AM
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I made mine as a clipped wing with an .46FX. Too much power. Dropped it to the .46LA, more than enough. Funny thing about Cubs, especially small ones is the more power you add, the more stroppy they become.
It's designed to fly on the wing and that might sound rather boring to many... believe me it's not once you "get it". There's a great deal of fun had and skills to be honed by learning to put on a marvellous aerobatic show under those conditions.
Power it anyway you want but... I'll guarantee that after a while you be pottering around at nothing more than 1/4- 1/3rd throttle 100% of the time... doing some marvellous stuff.
Then you'll be able to say... I get it.
Old 01-19-2017, 01:22 PM
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PaulWa11
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Yeah I just test fitted the OS .75 and it almost noise over'ed ahah time to find a 4 stroke or a smaller 2 stroke
Old 01-26-2017, 11:53 AM
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Need some help, with batteries its been a while since I've been flying and almost done my cub build (Yes I will post pic's). But my question is I need a receiver pack thinking lipo but not sure where to start?

was thinking https://hobbyking.com/en_us/zippy-fl...-3s1p-40c.html Would that be a good receiver pack?
Old 01-28-2017, 05:56 AM
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Do you need 12 volts for your receiver? Most run on 6. A 2 cell LiFe will work with no regulator, or you could use a 5 cell Nimh pack. If you go with a 2 cell Lipo, you'll need a regulator.
Old 01-28-2017, 06:57 AM
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http://www3.towerhobbies.com/cgi-bin...&I=LXDVCC&P=ML

I'm old school, I still use 2000mah nimh, never depleted one out in a day of flying yet but have a backup just in case. http://www3.towerhobbies.com/cgi-bin...&I=LXNHS4&P=ML

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