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Breitling L39 Blue EDF

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Breitling L39 Blue EDF

Old 04-15-2018, 09:43 AM
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Jack_K
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Default Breitling L39 Blue EDF

I got a Breitling L39 EDF jet in a trade. I can't find a manual for it anywhere. It has a 30" wingspan and every L39 model I've found has a 27" span. These all say the CG should be 1-15/16" back from the leading edge of the wing at the fuselage.
If I try to balance the plane there it would need a TON of lead in the nose to balance. They also say to use an 850 mAh 3S LiPo battery. That's awfully small. The FlyZone L39 uses a 2200 mAh 3S LiPo.

So I used the CG Calculator online and it calculated the CG to be at 3.34" back. That's a huge difference. I'll post a pic of the CG calculation and two typical L39s, but not my 30" one.

Meanwhile, does anyone know where it should balance and what size battery (volts and mAh) to use?

Jack

Old 04-23-2018, 01:20 AM
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Joseph Frost
 
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My cord is 320mm, CG is 85mm back from LE.
Measure your cord at the w/root and divide by '3.75'. What ever figure you get will be the CofG from the LE at the root. That's based on my TG 90mm 'Thirtyniner". Cheers.
Old 04-23-2018, 08:27 AM
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Jack_K
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Thanks. That would be 2.25 inches back from LE at fuselage. Still hard to do since it's so tail heavy.
Old 04-25-2018, 02:07 AM
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What size fan is in it? I don't recognize the model but 30" would likely be a 64mm fan, if you can count the blades or post a photo of the fan, and the Kv of the motor, even ESC specs would be helpful, I can tell you what battery to use. If it is a 64mm then 2200 3s would be the first choice and would make sense if you are having nose weight issues, don't add lead, add more battery to get to the calculated CG.
Old 04-25-2018, 12:06 PM
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Originally Posted by Extreme_RC
What size fan is in it? I don't recognize the model but 30" would likely be a 64mm fan, if you can count the blades or post a photo of the fan, and the Kv of the motor, even ESC specs would be helpful, I can tell you what battery to use. If it is a 64mm then 2200 3s would be the first choice and would make sense if you are having nose weight issues, don't add lead, add more battery to get to the calculated CG.
The fan is 64mm and has 5 blades. Here are two pics.


Old 04-30-2018, 04:44 AM
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If the motor is around 4000kv then 3 cells, anything up to 2200 to get your Cg right will be fine, I would run a 2200 3s myself. If its lower Kv, like 3000 then 4s but likely it will be 3700-4500Kv.
Old 05-02-2018, 09:03 AM
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Originally Posted by Extreme_RC
If the motor is around 4000kv then 3 cells, anything up to 2200 to get your Cg right will be fine, I would run a 2200 3s myself. If its lower Kv, like 3000 then 4s but likely it will be 3700-4500Kv.
I put in a 3S 2200 mAh that weighs 6-1/2 ounces. That got the balance pretty close. I'll see how it flies if the winds will ever die now around here.

Thanks for all the responses.
Jack

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