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My t-rex won't fly

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My t-rex won't fly

Old 12-20-2006, 03:02 AM
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Default My t-rex won't fly

Hi, just bought a lovely T-rex secondhand. It has the Align 3200 kv motor and a castle creations 35 amp speed controller. It is all set up and get light on its skids at half throttle.

I think the problem may lie in the lipo's. I am using the lipo's from my Zoom 400. That was a brushed heli! I have two lipo's 1 is the protech 1600mah lithium-ion 11.1v 10c, and the other a li-poly 1200 mah 11.1v 15c.

Could the problem be the battreys or should i look somewhere esle.

Thanks in advance

Darrell
Old 12-20-2006, 03:39 AM
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Default RE: My t-rex won't fly

What happens above half throttle?? Head speed die? Nothing changes? motor shuts off? Some more info is needed here.
Old 12-20-2006, 03:55 AM
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Default RE: My t-rex won't fly

Hi, sorry for lack of info. The head speed just drops. It seems ok until it is under load.
Old 12-20-2006, 11:30 AM
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Default RE: My t-rex won't fly

I should think those batteries are pretty inadequate for the T-Rex. I and all of my friends who fly the T-Rex use 2100MA 11.1 volt packs rated 15C and higher. I am getting good performance from the Align 2100 16C pack.

Try a new fresh 2100MA pack and see if that doesn't make an extreme difference.
Old 12-20-2006, 01:50 PM
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Default RE: My t-rex won't fly

I agree, those batteries probably aren't going to cut it on a Rexy.
Old 12-21-2006, 09:06 AM
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Default RE: My t-rex won't fly

The 10C pack will puffy like a magic dragon, but I would say if the 15C pack is fully charged, the 15C rating should fly the heli but not for long periods... I have the DN 1300mah 15C pack on my hughes 500E heli and it flies great but only for 6 min... The 2100 mah will get you to 9-10 min of easy flying... I think you have other issues like pitch/throttle curve...
Old 12-21-2006, 09:44 PM
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Default RE: My t-rex won't fly

I tried the 1300 15C pack and at a full charge, it will fly it, but not well and after about 2 minutes, the motor just shuts off. You need more battery. I have the 2200s coming, but they aren't here yet. Have been told that this will solve the problem.
Old 12-22-2006, 05:34 AM
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Default RE: My t-rex won't fly

Thanks all for your advice. I will get hold of some bigger batterys and try again. I thought the batterys where small but with them working on the zoom thought is wise to check with you guy's.

Darrell
Old 12-22-2006, 06:48 AM
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Default RE: My t-rex won't fly

It is also possible your head speed is simply too low AND your blade pitch too high. I wouldn't want to pull any fancy manouvers on a 10C battery but it should hover a TRex with no trouble.

Set the blade pitch at mid stick to zero degrees and the throttle curve to give around 60% - 70% power. That'll get the head spinning up quite fast at minimum load while its sat on the ground.
Limit the max pitch to 8 or 9 degrees to prevent sudden pitch increases bogging the motor. You can't use motor torque as the 10C battery would simply try to explode...

You still need to get a 15C or 20C battery pack, but head speed management is still important. You shouldn't rely on brute force from the motor to drag it into the air.

The EVO20 series is readily available in UK model shops. I have the 2150mah and 2500mah packs. Don't get the 2500, the extra weight uses up the extra power it can hold so you don't get any longer flying time...

Karyn
Old 12-22-2006, 10:54 AM
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Default RE: My t-rex won't fly

With the 11t pinion and the stock 325 fiber blades align estimate a peak draw of 22.7A. Your battery pack is rated to deliver 16A.
Although you probably aren't drawing at peak you should definitely cater for that eventuality. Driving packs at their max rated capacity will kill them quickly so a 2100 15 - 20c pack is what you need.

You might also consider retiring or at least testing your existing pack, the symptoms you describe normally indicate that at least one cell has been damaged ( over stressed).

Brett

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