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T-34 not taking off


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Robwadd999
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Joined: 13 Jun 2012
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PostPosted: Tue Jun 04, 2013 1:01 pm
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Hi my t-34 helicopter won't take off more than two inches my battery's are fully working I have been stuck with this problem for a very long time any help would be great
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tombo242
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Tue Jun 04, 2013 11:44 pm
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Hi Robwadd,

All I can say here is that the lifting power is too low to get out of ground effect. There are far too many causes of this to go through them all, but the three major ones are:

1. Poor batteries. My quad came with a Chinese clone battery which does not have 1/4 of the capacity of my Turnigy Nano-Techs although they have the same mAh rating. After two weeks' use the chinese clone is as bright as a Toc-H lamp.

2. Gears slipping somewhere or the mechanism clogged up.

3. The motors are failing - common with brushed ones. Can happen very quickly with some motors.

If you could give more detail; i.e. how did you check the batteries? Do the rotors turn easily? Are the props damaged? How often have you lubricated it and with what? We may be able to help. Right now it's like asking you "My cat won't eat - what's wrong with it?"

Sorry,

Tom.
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Robwadd999
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PostPosted: Wed Jun 05, 2013 1:38 am
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Hi my li po 2 cell 7.4v battery voltage at full chare is 8.3 volts. I'm not sure if this is right could you tell me if this is right so I could give you more info.
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jathanjr
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PostPosted: Wed Jun 05, 2013 3:00 am
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Yes the 8.3 reading is correct for this battery
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tombo242
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Wed Jun 05, 2013 5:55 am
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Hi Robwadd,

A fully charged li-po battery should read 4.2V per cell, so your 2 cell should read 8.4V if fully charged. Being 0.1V low should not make a lot of difference to flight with a good battery, but it is the charge that it takes to get to that level which counts as well as its internal resistance which rises with use.

Your battery should not ever be discharged below a working voltage of 3.0V/cell. The higher the internal resistance the quicker it will drop to that level. In practice that means that the voltage measured out of the heli and after flight may be anywhere from 3.3V to 4.0V depending on battery health. Many of us set our working cutout warning levels at 3.2V or even higher. This gives around a 20% or more charge left in the battery.

Now, if your battery is a 1000mAh one then you should be putting in around 800mAh charge to bring it back to full i.e. 80% of 1000mAh. You may find with a failing battery that it only requires a portion of this charge to refill it. That charge is all you have for flight. The actual voltage is not so important; the charge retained is.

As the battery deteriates the charge retained grows less and the flight performance drops. There is no way to stop this. I have batteries now 4 years old but despite vary great care, they only give 1/2 the flight time of my (same capacity) new ones and they only take 1/2 the charge to bring them to full voltage.

Hope this helps 8.3V for a full charge is not a healthy sign, (sorry jathanjr).

Tom.
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Robwadd999
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PostPosted: Wed Jun 05, 2013 1:10 pm
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Hi thanks so would should I do next buy a new one. Or is there aiming else I can do?
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tombo242
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Wed Jun 05, 2013 9:33 pm
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Hi Robwadd,

This is a difficult one, certainly a new battery might fix it but there is no guarentee that it will do so.

I assume that you are using the stock charger and so have no means of checking the actual charge put into the battery and also you have no way of measuring the amperage taken by the helicopter. To get tools to do this with any form of accuracy would probably cost more than the T-34 did! A good choice would be a friend with a good battery that you could borrow just to try.

Check the freedom of movements of all the parts. Then answer these questions, it should help us decide what might be wrong:

1. Does the heli spin as it tries to rise?
2. Are the blades locked solid to the drive shafts and gears?
3. Does the battery connector get at all hot?
4. Is there any sign of burning anywhere in the helis' electronics?
5. For how long will it spin on the ground before it starts to slow down?

You don't have your location filled in so I have no idea where you might get that battery from if you decide to try that. Most of us always have at least 2 or 4 batteries for each machine that we have, this allows longer flights between charges and spreads the strain on the batteries.

Tom.
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Robwadd999
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PostPosted: Wed Jun 05, 2013 9:51 pm
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Hi
1.no the helicopter dose not spin as it rises
2.yes they look like there locked when I trun both the blades the wheel that the motters are conetted spins.
3.a little but not very much.
4. There is a sticky gel looking thing near the motters but might just be glue.
5. I'm not too sure but when I did It didn't slow down for a least 2 mins.
One of the motters gets very hot and there others isnt hot at all.
Hopes this help is there anything you got from This.
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tombo242
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PostPosted: Fri Jun 07, 2013 1:32 am
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Hi Robwadd,

One motor getting hot and the other staying cool, sounds quite significant.
It looks as if you have a poor motor. It is possible that the gyro is compensating for this by shutting back the good motor to stop the spin that would normally result.

This 'hot' motor could just have bearings that require lubrication, on the other hand it could be something that will only be cured by replacement. I wish I could be more helpful here but without having that heli on my bench I am only guessing.

Tom.
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Robwadd999
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PostPosted: Fri Jun 07, 2013 2:25 am
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Okay so witch one do i have to replace and witch one should i use lubrication on.
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Burgess
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PostPosted: Fri Jun 07, 2013 7:29 am
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Hi Robwadd,

Best thing to do is drop both motors out and inspect them, including the brushes and commutator. Test each motor in turn on one of the speed controller connections.
Use the best running motor and test the other speed controller. If one motor is defective, it would be best practice to replace both motors at the same time.

Burgess
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Robwadd999
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PostPosted: Sat Jun 08, 2013 3:48 am
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Hi sorry I miss read your replay so should I try lubricating it first and if it dose not work then should I find a replace ment.
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Burgess
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PostPosted: Sat Jun 08, 2013 4:28 am
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Try lubricating the bearings on both motors first.
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pjdog
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PostPosted: Sat Jun 08, 2013 9:04 pm
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I use to have a Big Lama. I was always losing a motor. Seems the bearing on one of the motors (Back motor me thinks) would fail.
I wanted to replace it with brushless motors but that was over $ 100.00 which was what the Big Lama cost.

The fix was ball bearing motors. I could use the same motor control and the motors were very cheap (Didn't cost much).

If you must replace a motor - replace both with ball bearing motors.

jack
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tombo242
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Sat Jun 08, 2013 11:00 pm
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+1 on that Jack.

Tom.
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