Throttle blip makes me flip! (video)

K

kevino

Active Member
Hi and Merry Christmas!

I'm looking for some help with an issue I've been dealing with for a while now. I'm flying an armattan chameleon with all armattan stuff, armattan velvet motors and 30a escs and spracing f4s board. I've been encountering this problem where occasionally after a crash I start having motor issues. It doesn't matter if the crash was bad or seemingly harmless. afterward I go to take off and one of the 4 motors will fail, more specifically one motor will seem to stop on throttle increases. Hovering is no problem, I could hover in place til the battery dies and nothing would happen. Its as soon as I give it any kind of throttle that it will flip. The ONLY thing I have found to solve it is to replace the motor (or sometimes its the esc). Armattan assures me the motors are solid so I think its something I have setup wrong. The only non-stock thing I have done is to add soft mounts so I have used screws that are slightly longer. The screws do not make contact with the stator, I have checked and rechecked that....however they are a little closer than the stock screws. Is it possible that during a crash the screws are causing a short that damages electronics? Or could it be something with calibrating esc's? I'm at such a loss with this and it keeps happening I've gone through 6 motors and 2 esc's with this situation. Any thoughts? Thank you !

The video showing hovering and slight throttle increase resulting in flip:
 
I wanted to share another video perhaps it might help someone who understands more than me. This video just shows using betaflight motors tab to spin motors up quickly to full throttle. 3 others perfectly fine but the 4th does this stuttering crap. I've also tried a couple combinations of older (but working) motors and esc's I had laying around and still it happens its so frustrating!

 
Quite possible a problem with your flight controller. A little bit of work, but I'd change your #4 ESC signal wire to #5 pad and change your resource in the CLI accordingly
 
Thanks for the reply! I'm not entirely sure, but I don't believe this board (spracingf4s) has a 5th pad to work with. As far as I can tell it's just the 4 corners of the board with esc pads. Is there a multimeter test I could do? I've just played around with measuring resistance between a bunch of pad combinations and they seem to be consistent but I don't really know what I'm looking for.
 
if your confident in holding your quad, simply arm, then dip each corner, that motor should speed up and resist the downward movement. Sometimes this takes a little while to heat the esc/motor up to show the issue (week motor/esc). It looks like Left Rear motor is the issue, good luck be safe.

EDIT: you might want to re-calibrate the esc's, just to make sure that is not causing an issue.
 
kevino said:
I wanted to share another video perhaps it might help someone who understands more than me. This video just shows using betaflight motors tab to spin motors up quickly to full throttle. 3 others perfectly fine but the 4th does this stuttering crap. I've also tried a couple combinations of older (but working) motors and esc's I had laying around and still it happens its so frustrating!

Click to expand...
Hey Kevino, did you ever figure out what was making the motor on your
Chameleon​
stutter like that when you punched the throttle? Im having the same issues on my beater quad (Wizard) and its driving me nuts! Thanks for any thoughts, jon
 
WhitestarFPV said:
Hi all, any updates on this issue? Im having the same problem and cant find much info specifically.
Click to expand...
Basically a matter of doing some guess and check, swap motors if still same behavior you know it's not the motor, swap ESCs if the problem moves with the ESC then you know it's probably the ESC. If like the OP you are swapping ESCs and motors and still experiencing the same problem then would be more suspect of the FC or PDB. Like someone already mentioned here using another signal output from the FC to the ESCs is a way to eliminate one signal line from being a problem since if it's rolling over from one edge (just one motor stopping) then the FC or PDB overall probably isn't an issue.

Blackbox logs can help with getting a better idea of what's happening as well, would record the actual flight test in slow mo (video) if possible to see what's going on physically and compare with blackbox logs as well to see if you can make sense out of what's happening in terms of control signals and/or gyros at the time (or just before) the quad flips.

If you can hover and it just drops out eventually it's hard to judge if it flips on take off it's usually backwards prop, motor spinning backwards, board orientation problem or something else that's easier to fix.
 
wafflejock said:
Basically a matter of doing some guess and check, swap motors if still same behavior you know it's not the motor, swap ESCs if the problem moves with the ESC then you know it's probably the ESC. If like the OP you are swapping ESCs and motors and still experiencing the same problem then would be more suspect of the FC or PDB. Like someone already mentioned here using another signal output from the FC to the ESCs is a way to eliminate one signal line from being a problem since if it's rolling over from one edge (just one motor stopping) then the FC or PDB overall probably isn't an issue.

Blackbox logs can help with getting a better idea of what's happening as well, would record the actual flight test in slow mo (video) if possible to see what's going on physically and compare with blackbox logs as well to see if you can make sense out of what's happening in terms of control signals and/or gyros at the time (or just before) the quad flips.

If you can hover and it just drops out eventually it's hard to judge if it flips on take off it's usually backwards prop, motor spinning backwards, board orientation problem or something else that's easier to fix.
Click to expand...
Thanks for the fast reply! I had an esc burn up after a slight crash into grass and I replaced it but then the motor that the esc was running was cutting out and then stopped spinning all together. So I replaced esc again and still the same issue. Then I flashed my FC to betaflight 4.0.4 and flashed escs to 16.7 and it fixed that motor but the problem went to another motor. In Betaflight motors tab it only does it when I move the fader fast from 0 to full throttle but when I slide it up slowly it will run at full throttle without any glitches or stutters.. I dont understand why the problem moved from one motor to the other after the flash? Thanks again, jon
 
Okay one thing to do that is easy is just calibrate the ESCs so they know the min and max to expect from the FC since things were flashed sort of recently that could be an issue although I'm not really sure what an ESC is supposed to do if the input signal is above max expected (would think max throttle but perhaps considers it a bad signal). If you are running dshot 1200 maybe try a simpler/slower protocol to the ESCs in the betaflight config (dshot600 or multishot, most ESCs support a small handful of protocols). Recently upgraded mine to 4.0.4 as well after replacing FC and ESCs so still in the process of getting things tuned.
 
With props off can calibrate ESCs by running throttle to 100% in motors tab with battery unplugged and then plug in battery you'll hear half the startup tone then reduce throttle to 0 and hear a second tone, then done.
 
wafflejock said:
With props off can calibrate ESCs by running throttle to 100% in motors tab with battery unplugged and then plug in battery you'll hear half the startup tone then reduce throttle to 0 and hear a second tone, then done.
Click to expand...
Cool, I didnt know that. In Betaflight or Blheli suite? And on this one I just have Blheli S 20 amp esc's.. It's my beater quad now that I've built the Iflight xl5. But im trying to be all carefull with it untill I get the Wizard back in the air because I dont like being grounded lol..
 
WhitestarFPV said:
Cool, I didnt know that. In Betaflight or Blheli suite? And on this one I just have Blheli S 20 amp esc's.. It's my beater quad now that I've built the Iflight xl5. But im trying to be all carefull with it untill I get the Wizard back in the air because I dont like being grounded lol..
Click to expand...
In betaflight can do them all at once with the master slider in the motors tab.
 
Ok, I tried that and it worked like you said but unfortunately didn't fix the motor issue. This things driving me crazy... Hey but atleast I learned something new! Lol. So strange how it only does it in betaflight when i raise the slider fast to the top but if i slide it back down to around 17-1800 it picks back up and runs. And if I just move it slowly I can raise and lower it without issue.
 
Hi Whitestar, unfortunately for me the only solution that ever worked was replacing both the motor and the esc. I have experienced a couple other times where just replacing the motor worked as well, so I would suggest trying that first. I believe the correct term for what we are experiencing is called a motor "de-sinc"

My main problem was that I was having multiple motor failures after minor crashes. I'm convinced that it had to do with one of two issues I had. One is that I did not have my esc's flashed correctly (as mentioned above by waffle). For me personally, I was using the stand-alone verison of BLHeli Configurator and betaflight. Here is the video that showed me how to properly do that (I like this video because not too in depth just easy description of how).


The 2nd issue I believe that i had was that my motor screws were too close to the motor windings (plus i have soft mount). I believe that after a crash the screw would either make contact with the windings or come so close as to create a short circuit between the screw and winding. I've since added some washers to back the screw tips away from the windings. Here is a good video for testing to see if the screws are creating a ground path.


I hope one of these helps!
 
Thanks alot! I'll check them out when I get home this evening. I'm thinking a new motor/esc too. But the weird thing is that the day befor it was a different motor doing the same thing until I flashed the FC to 4.0.4.
 
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