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Formosa not taking off

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Old 05-09-2005, 11:35 PM
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barelias
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Default Formosa not taking off

I got a formosa with E-go brushless which is 3700 rpm , 25amp phonex,Gws gear(B) and i made a 9cell nimh pack. Its not taking off from ground even after 50 ft or more. the prop recommended for this brushless was 9x4.5. tried the 9x4.5 and the 8x6 but it wouldnt take off or fly. At first motor was cutting off but after fully charging the battery pack ,motor is not cutting but still wouldnt take off. I didnt want try hand launching again after my first crash.Dont know what to do! should i make 10cell pack ?would a 3700rpm handle the 10cell with 9x4.5prop?
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Old 05-10-2005, 09:39 AM
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Matt Kirsch
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Default RE: Formosa not taking off

Unfortunately, that's not enough information to make a determination as to your problem.

I personally have never heard of an "E-go" brushless motor, and from the lack of other responses, we can safely assume nobody else has, either. Can you provide a website with the motor's specifications? 3700 RPM only tells us how fast it turns on a single Volt of electricity. It doesn't tell us anything about how much power it can handle, or how it should be used.

What "9-cell NiMH" are you using? If the motor was cutting out, it sounds like you're drawing more Amps from the pack than it can provide. That means the pack is too small, and adding cells will only make the problem worse. How many mAh, what size cells, and where did you get them? Cell capacity, cell size, and cell quality have a huge effect on how the battery reacts to heavy loads, and how much power gets to the motor.
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Old 05-11-2005, 12:21 AM
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Default RE: Formosa not taking off

E-go brushless motor is not so famous ,here is the info came with it:
Rpm(kv) : 3700
Current : 0.70ma
Resistance : 0.064
ESC rating : 15A
wieght :66g
length: 40mm
Diameter:20mm
Shaft Diameter:2.3mm
also they recommend 11.1v li-poli
about the battery pack i made , its AAA 800mah
the motor seem to be giving good thrust,but is it ok to say if plane is not taking off then it will crash with hand launch?
The AAA's, are they as good as the sub c's?
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Old 05-13-2005, 05:56 AM
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steve ypsi mi
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Default RE: Formosa not taking off

the phonix 25 is probably set to hi on the voltage cut off, if it is set at 8 Volts or higher on the nimh batteries it will cut off because the battery drops volts fast and then back up but it is enough to shut the throttle off, try setting the volt cut off down to about 4 volts since you are using nimh batteries, on lipolys the setting is 6 volt for a 2 pack and 9 volts for the 3 cell lipoly.
your motor, 3700 KV times I will say 8 volts the batteries you have 9 cells - 8x3700= 29000 divided by gear ratio 4.43- 29000=6681 rpm at the prop, that is pretty slow for the props and pitch you gave, the smaller and lower prop size and pitch need a lot more rpm than that, just a guess put a 9070 or 1047 on it and it should improve a lot. the best thing you can do is use 3 cell lipolys, they are 11.1 volts times 3700 KV =41070 divided by the gear box 4.43 - 9270 rpm at the prop which would amke the small props a lot more efective. .
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Old 05-13-2005, 01:07 PM
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Default RE: Formosa not taking off

FWIW, I've never seen "AAA" nimh cells that were happy putting out more than about 6 amps. There's no max. efficiency current listed for the motor, but if it has a 15 amp ceiling, I'd bet you're well below the most efficient current level. Personally, if I had to use nimh cells on a motor with those specs, I'd be looking at 8 cells of 2/3AA or 2/3A to start with. They handle quite a bit more current than the AAA cells do, and the 2/3AAs aren't TOO much heavier. After a bit of searching, it appears that motor is very similar to a Feigao 1308416L as listed by Balsa Products. So with the 4.3:1 gearing you have, it appears that 7-8 2/3AA cells like CBP 750 and a GWS 9x5HD or 10x6HD prop might be a good starting point.
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Old 06-05-2005, 05:28 PM
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Default RE: Formosa not taking off


ORIGINAL: barelias

I got a formosa with E-go brushless which is 3700 rpm , 25amp phonex,Gws gear(B) and i made a 9cell nimh pack. Its not taking off from ground even after 50 ft or more. the prop recommended
Sorry guys, for my money, and I'm not familiar with this setup at all, any light aircraft that will accelerate for 50 ft and not take off with the recommended propeller, the first thing I'd check is the center of gravity. Those are all the symptoms of a CG that's way too far forward. Beyond the LE even.

Esp when the writer alludes to having cracked up from a hand launch. If you hand launch and can't keep the nose up......check the CG.
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