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Mikado V-BAR Mikado V-Stabi/V-BAR Flybarless System Software and Hardware Support


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Old 05-20-2012, 04:57 PM   #1
OnTheSnap
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Default Momentary loss of control - Aileron sensor out of range

I'll post a log later.

At a funfly this weekend I had 4 instances where the cyclic stopped responding and then came back a second later. It doesn't happen every flight. In the log I have observed one of 2 warnings in each instance - Cyclic ring active or aileron sensor out of range.

In all the failures, I gained control quick enough to just barely save the model.

I tried swapping the black sensor with a blue, but had the same issue again.

This is on a Goblin, Torq servos, WR BEC, 8.4V.

I had a ESC failure maybe 20 flights ago where a phase on the ESC failed that melted down the motor. Flames shot out of the motor and left some scorch marks on the front servo.

It seems reasonable that a momentary servo lock up could produce the above errors. Basically the swash won't move where commanded so the system maxes out it's input to the non-functioning servo which produces the cyclic ring message. However the aileron sensor out of range error makes little sense if the servo is at fault.

I have never seen checksum errors, antenna switch or rx packet errors and the model is 23 ohms from tail shaft to motor mount. I also tried swapping the sat wires to no avail. Again replacing the vBar sensor showed no improvement.

I'm thinking I could use a heat gun on the front servo and set pitch pump to 100. Then pump collective to see if I can get the servo to reproduce the failure on the bench.

Any other ideas or experiences?
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Old 05-20-2012, 05:54 PM   #2
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i had kinda similar issue yesterday i lost my all control of my tail for about 2 seconds on a huricane as it was flying towards me ..then the heli gained contol again just in time what a scary situation that was .My log has full of swtched antena errors ,i noticed my static wire was not getting a good connection so i replaced that just waiting to fly it again
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Old 05-21-2012, 01:34 AM   #3
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The same happened to me on my Mini Protos about 2 weeks back. All axes reported sensor out of range for about 2 seconds and the whole system went into failsafe. No idea what happened
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Old 05-21-2012, 01:54 AM   #4
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Sensor out of range = sensor working, but heli moves faster than 500 degree/sec
Meaning, not the sensor unless you get tons of this messages.

Something made the heli move fast, very fast, static hit is always a suspect in those cases, but a glitch in form of a bad cable or connection is doable also.
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Old 05-21-2012, 02:11 AM   #5
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I think if the Heli even momentarily hit 1.5turns per second you would have noticed the jerk. So I think the sensor out of range is either a sensor fault, or connection fault, or interference of some kind.
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Old 05-21-2012, 03:10 AM   #6
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Not if you are already at for say 360 degree turn (roll or other movement), a notchy servo is all that it takes, or a chafed cable.

OP has tested another sensor so that is not the case.

could be a broken servo port on the vbar main unit, wiggle each cable and see if servo dies.
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Old 06-20-2012, 06:01 PM   #7
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I fixed the issue by dumping the BEC and using a RX pack. But now I have another interesting problem.

If I do full stick forward flips, the heli will do a couple, and then suddenly pause (while vertical usually) move slowly for a second and then recover to normal. It won't do this in back flps or aileron rolls. Just forward flips.

I don't see any binding issues, and the cyclic ring is at 100, but seems reasonable. So long as I don't do full stick elevator flips, it flies normally.

Seems like the possibilities are:
1) Servo problem. Although it flies great and it is just forward flips. I could swap out all the servos. :-/
2) Swash binding issue? Swash seems OK
3) My numbers are pretty high numerically for 8 degrees of cyclic. like 100 for cyclic, and 105 for cyclic ring. Maybe I should move the balls on the servo horn out by one to bring the values down into a normal range?

Pretty funky issue. Never seen anything like this.
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Old 06-21-2012, 12:17 AM   #8
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Yeah sounds like early-phase brain tumor.
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Old 06-21-2012, 02:25 AM   #9
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TX issue maybe?

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Old 06-21-2012, 04:48 AM   #10
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Start with going in under Expert Cyclic and press Reset, then check if it still does it.
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Old 06-21-2012, 10:25 PM   #11
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Brain tumor? LOL.

Thanks for the suggestions. The problem is finally solved and it was a setup issue. The elevator servo simply did not have enough throw. At full elevator plus near full pitch the swash would flatten out as the 2 front servos moved more than the elevator servo. The problem was solved by simply moving out a hole on the servo horns.

Seems trivial now but this issue was subtle and has given me some terrifying moments in the past few months. It manifested like a true radio lockout and even caused a small crash once.
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Old 06-22-2012, 02:01 AM   #12
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Wow, glad you found it, survivor.

What would the setup-check step be? Measure the full cyclic at full collective at 4 rotation angles?

(Can you tell I still haven't used my digital pitch gauge?)

Rock on.
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Old 06-22-2012, 02:13 AM   #13
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Quote:
Originally Posted by OnTheSnap View Post
The problem was solved by simply moving out a hole on the servo horns.
I think the Goblin has a sufficient range as it comes to collective and cyclic pitch.
What's your Cyclic Throw value right now? (must be lower, right?)

I just can't imagine this being the right solution for your problem...

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