Tricopter - motor stop in mid air - Discussions

Dear All

Yesterday I flew my Tricopter successfully in Loiter and RTL mode, and the thing put a smile on my face until I decided to fly FPV and power on the Video TX on the Tricopter, it flew for a minute in stable mode then suddenly simply hovering all the motor stopped and crash, nothing serious couple of arms broke and one prop is gone.

I am trying to troubleshoot the problem in order not to repeat it again and I would appreciate the help.

I am running a separate 5V/5A BEC/850mAh Lipo for the ACM 1280, RX and tail servo (Hitec HS-65MG), the BEC output is connected to IN8 pin (ACM RX side pins), not like in the manual where I should connect it to the (ACM OUT side pins).
The motors/ESCs are running on separate battery 2200mAh.
The FPV Video TX is 1.3Ghz 800mW (12V) almost 30cm away from the Rx and ACM and it takes its power directly from the 850mAh battery balance port.
The camera is a GoPro and it is running from its built-in Battery.

The crash (All the motor stopped) after almost two minutes after I plugged in the Video TX.

Now can this be the problem:

When connecting the 800mW Video TX to the 850mAh battery this caused for the voltage from the BEC to drop down after two minutes and caused the ACM to brownout? (Solution put a third battery only for the Video TX).
Or May be the 1.3Ghz caused a noise interference that affected either the 2.4Ghz RX or even the ACM? (Solution put a low pass filter on the TX antenna to filter all the higher frequencies above 1.4Ghz).
Or is there another reason that caused the motors to stop in mid air.

I really appreciate all the help to troubleshoot this problem.

Did the ESCs beep during/after the crash? One possibility I would add to the list is ESC configuration for cutout voltage and cutout type. This is one reason your motors would stop in mid air, but when I "learned" about this on my first quad, it was not all at the same time, as soon as one motor stopped, the voltage rebounded, so the others did not cutout. In my testing after (I had it tied down during the initial problem and during my testing) I kept giving it more throttle, and a second motor stopped. Then I realized what it was.

But since all the motors stopped, this would not be my first choice for what happened.

Does it work now? Or is it possible that the PDB got pushed too much, and became a fuse? Losing all motors at the same time is the most important clue, I think. It suggests to me a power problem, with the entire system or with the APM. If the ESCs made noises during the crash, I would think of the APM. If they were completely silent, before and after, then I would think it is the PDB or cabling. If they stopped, and after the crash made noise then it might be something less permanent, and could be any of these things and more, maybe?

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Moderator

Michael Pursifull November 20, 2011 at 5:48am

Did the ESCs beep during/after the crash? One possibility I would add to the list is ESC configuration for cutout voltage and cutout type. This is one reason your motors would stop in mid air, but when I "learned" about this on my first quad, it was not all at the same time, as soon as one motor stopped, the voltage rebounded, so the others did not cutout. In my testing after (I had it tied down during the initial problem and during my testing) I kept giving it more throttle, and a second motor stopped. Then I realized what it was.

But since all the motors stopped, this would not be my first choice for what happened.

Does it work now? Or is it possible that the PDB got pushed too much, and became a fuse? Losing all motors at the same time is the most important clue, I think. It suggests to me a power problem, with the entire system or with the APM. If the ESCs made noises during the crash, I would think of the APM. If they were completely silent, before and after, then I would think it is the PDB or cabling. If they stopped, and after the crash made noise then it might be something less permanent, and could be any of these things and more, maybe?

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