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Old 07-15-2014, 09:44 AM   #1
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Default Bizarre ESC behaviour

I have just finished a DB Sport & Scale Auster fitting a Turnigy DLuxe High Voltage 80A ESC. In all but one respect the motor/ESC behaves as I would expect. However, there is one, v dangerous exception. If I turn off my TX rebooting it for a range check (Futaba 14SG), the motor bursts into life at maximum revs! It only stops when I restore my TX to powered-up. In other words, if power is on to the ESC and the receiver BUT NOT to the TX, the motor runs uncontrolably at full revs which is very dangerous. I have tried all the checks I can think of without a remedy to what in 15 or more years of flying electric, is a bizarre, strange phenomenon. Any ideas please?
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Old 07-15-2014, 10:03 AM   #2
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That's why you never turn off the tx when the plane is powered up.

Tx on first, then the plane when powering up.
And the tx turned off last when powering the plane down. One of the most important rules there is when flying.


One other thing. If your rx has a fail safe, it sounds like you had the throttle set wide open when you set fail safe. Might want to check that too.

When I die, I want to go like my Grandfather did, in his sleep...... Not screaming like the passengers in his plane.
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Old 07-15-2014, 10:16 AM   #3
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My bet is that you reversed the throttle channel after binding.

REMOVE PROP. (so if the motor starts unexpectedly you won't get cut)

Set throttle to 0 and go through your binding sequence.

That should fix it.
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Old 07-15-2014, 10:24 AM   #4
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The good old Futaba Reverse throttle strikes again !!

Nigel

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Old 07-15-2014, 10:51 AM   #5
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yep, never ever turn off the transmitter before you turn off the planes power source, never, strange sheet will happen

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 07-15-2014, 01:01 PM   #6
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Originally Posted by fhhuber View Post
My bet is that you reversed the throttle channel after binding.

Yep, that's my bet too. It's a common issue with Futaba and e-power where throttle needs to be reversed to operate normaly (why do Futaba still do that?)

Just re-bind with the throttle in the closed position and all should be good.

Of course the other are correct in that you shouldnt turn off the Tx with the model powered up, but even so the failsafe should be set to be 'safe' if you do.

.
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Old 07-15-2014, 03:45 PM   #7
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It can happen just by use of a different ESC brand from your norm... because some need throttle reverse one way... some need it the other. If you have only used types that "wanted" throttle in "normal" direction then this can be quite a surprise.
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Old 07-15-2014, 04:47 PM   #8
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Originally Posted by solentlife View Post
The good old Futaba Reverse throttle strikes again !!

Nigel
I agree, I'll bet it has something to do with this. But not being familiar beyond this with Futaba, I couldn't know exactly what. The rx doesn't have a failsafe mode? Perhaps as already suggested, you initially bound the tx and rx before reversing the throttle output from the tx, and that's what your rx 'remembers' and resorts to what is actually full throttle when it loses signal from the tx. So maybe re-binding in this case while the throttle is closed and now outputting the proper signal would help.

Be careful, and good luck. I just had the pleasure of helping patch someone up before getting him to the hospital for a prop bite. Hate to see it happen to anyone.
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Old 07-16-2014, 07:57 PM   #9
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Default The dreaded reverse channel 3

Yes, you are right - it was a Failsafe issue. However, I was setting up a new model and without a prop. I learned about that one decades ago! The irony is that I had failsafe configured on my Futaba 14SG and had set it to 0.0. I now know that it should have been set to 100 and as soon as I put that right the problem was solved. Futaba are not the only TX maker who require channel three reversing - or so I am told.
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Old 07-22-2014, 12:33 PM   #10
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Another Futaba one to watch out for,(possibly others) if you reverse a channel that has a mix on it, to change the switch position to activate said mix.
It will reverse the other channel also that is part of the mix.

Had flaps set up on a plane, and normally I set the switch so that in the up position the flaps are up, and down is down. Somehow I missed this one, and found it on pre-flight. No biggie, I reversed the flap channel so it worked correctly.

Forgot about the elevator mix on the flaps. Big mistake. I had it on a 3 position switch. Settings for normal flight/no elevator, take off/slight down elevator, and landing/big down elevator.

Well reversing the flaps to correct the switch also reversed the elevator.

Take off was not pretty. Ballooned into the air and made an almost loop. Darn ground got in the way. Yep, flaps in take off position now had added up elevator to an already configured excessive lift condition.

New note to self: if the flaps go down, make sure the elevator does too.

When I die, I want to go like my Grandfather did, in his sleep...... Not screaming like the passengers in his plane.
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Old 07-22-2014, 03:16 PM   #11
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Originally Posted by Glacier Girl View Post

New note to self: if the flaps go down, make sure the elevator does too.
Flap pitch depends on flap location, sometimes up sometimes down (that whole high wing low wing thing)! So no this isn't a 100%.

I have learned NEVER use flaps on first flights. Deploy them in the air, up and at slows speeds.

Sorry man...

Mike
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Old 07-22-2014, 07:59 PM   #12
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Originally Posted by grapher@btinternet.com View Post
I have just finished a DB Sport & Scale Auster fitting a Turnigy DLuxe High Voltage 80A ESC. In all but one respect the motor/ESC behaves as I would expect. However, there is one, v dangerous exception. If I turn off my TX rebooting it for a range check (Futaba 14SG), the motor bursts into life at maximum revs! It only stops when I restore my TX to powered-up. In other words, if power is on to the ESC and the receiver BUT NOT to the TX, the motor runs uncontrolably at full revs which is very dangerous. I have tried all the checks I can think of without a remedy to what in 15 or more years of flying electric, is a bizarre, strange phenomenon. Any ideas please?

Something else I've found with my Spektrum DX8 transmitter. That involves the throttle kill switch mix. When programming in the throttle kill switch function (I use the Gear Switch), make certain your throttle trim is run down to minimum!

If it isn't, flipping the throttle kill switch can cause your electric motor to run at "idle" speed. Not good, when you've got a 19 inch diameter prop on a 3000 watt motor!

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Old 07-22-2014, 08:40 PM   #13
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Dennis, not that all this would help the OP as he's on Futaba, and his problem was with the tx off, but sounds like your throttle cut setting just needed some fine tuning. It's strange for me to suggest something to you, as you are so knowledgeable with all the electronics! But I wonder if you missed this one. You're aware of the need to adjust the kill position output from Spektrum tx's to avoid your problem? By default, the tx's idle output is -100, but the throttle kill goes well below that. You have to set the kill position to be the same as the idle output to avoid the esc learning a new idle position when you use throttle kill. Although, I didn't think you could trim down enough to overcome the default kill position, so I don't know if you already adjusted it. But then if you got it adjusted right, this shouldn't happen. Yeah, I'm a bit confused! Just trying to figure it out.
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