Hey all,

For the past week, my new drone has been flying quite well. Faster than I'd ever imagined it would after hoping to be better than the Avata I gave back, but now after a week of behaving, the drone is losing it's mind. I am too given I BUILT this drone so I could get FPV footage of a vacation in ten days, and ideally, not lose it at the bottom of a canyon. So I need help.

Link to problem: 

As you can see, something is going on here that is causing a sudden loss of control of the drone. I am not losing Rx. I've never had a warning on screen, or audibly, and as you can see during the first event, I was able to save it because I still had signal.

Of the many things I'm confused about, is why the drone started off by flying wonderfully and without hiccups. As the week has gone on, and yes I've landed myself in a number of trees and grass more than a few times, things have gotten worse and worse, to the point where I don't even trust it to make it through a pack. So whatever has happened, it seems to be cumulative.

The drone seems to fly alright for a minute or two on most packs. It seems the issue gets worse as the battery gets lower (starting at 25.2V and landing between 22.0V and 21.0V). During the attached video of BF BB, I used Bat Voltage as the red line, and Amps as the yellow on bottom. It APPEARED there was a clear drop in volts and spike in amps watching that one video. During normal flight, those two lines almost always steered clear of each other, but during those jerks, they overlap. However, I've watched some blackbox data of mine where the jerks were happening WITHOUT those spikes. So I'm unsure if they're related.

Link to spikes: 

Someone mentioned the other day that my 35A FC isn't up to snuff for 6S batteries and Xing-E Pro 2207 motors. Could this be the case? Is
I am using some basic rates, and have not changed the PID settings away from the FC's default.


Here's what I believe I have ruled out: 
1. All props have been changed and are undamaged. 
2. All props have been tightened by holding the bell in my hand and secured tightly using a socket wrench. Someone here told me to tighten them as much as I can, and I am. Within reason obviously.
3. When fired up in BF. All motors spin up seemingly properly, and sound the same. I don't hear any grinding or sketchy noises while hand turning or while powered in BF.
4. When I power them in BF, I run my finger along the bell and all 4 motors seem to be stable and of uniform shape. All of the posts coming out of the top spin perfectly and have no bends or wobble. All of the motor screws are tight, none of them protrude into the bell, and the bells appear to be clean.
5. During flight, my battery straps and balance leads are secured and are not hitting the props. My battery is strapped in as tightly as it can be.
6. All arms and screws are seated, and tight. There is no play in the frame at all.
7. When powered up on battery, I get all needed beeps, and all lights. I also get all the lights in BF.

This is about all I can think of at the moment as it's 3am, but I definitely need help. I'm happy to provide any black box data I can grab as well as what I already have. I just don't know the parameters ya'll would need.

Nazgul 5 Frame 
FC - SpeedyBee F7 Mini 3-6S 35A 8-Bit 20x20 w/ 4-1 ESC - A review or two said these ESC's could be dodgy, maybe this is my issue. I've ordered the iFlight Blitz Mini 55A AIO Stack as a replacement.
DJI O3 VXT
HGLRC Mini M100 GPS
Radiomaster RP1 ELRS
CNHL 6S 1500mAh 100C batteries

Please, and thank you for your time guys/gals.

Where the quad suddenly goes into a death roll is the classic symptoms of an ESC desync. If it all started off fine and has been getting progressively worse over time then that would point the finger at a fault with the ESC. You probably have a failing MOSFET on one of the motor outputs.

If you add all the RC commands and motor outputs to the blackbox log and you then see that one or more of the motors goes to 100% without any real change in stick movements it means that the ESC for that motor isn't providing the required power to the motor to keep the attitude of the quad stable, so Betaflight commands more and more power to that motor (all the way to 100%) to try and get the quad stable again, and when that fails to do anything the quad simply ends up doing a death roll and falling out of the sky.

I'm sure that once you've replace the ESC everything will be back to normal again.

(15-Sep-2023, 09:31 AM)SnowLeopardFPV Wrote: Where the quad suddenly goes into a death roll is the classic symptoms of an ESC desync. If it all started off fine and has been getting progressively worse over time then that would point the finger at a fault with the ESC. You probably have a failing MOSFET on one of the motor outputs.

If you add all the RC commands and motor outputs to the blackbox log and you then see that one or more of the motors goes to 100% without any real change in stick movements it means that the ESC for that motor isn't providing the required power to the motor to keep the attitude of the quad stable, so Betaflight commands more and more power to that motor (all the way to 100%) to try and get the quad stable again, and when that fails to do anything the quad simply ends up doing a death roll and falling out of the sky.

I'm sure that once you've replace the ESC everything will be back to normal again.

I believe this is the data you were referring to. I'm getting all sorts of unhappy spikes in the motors.



Thank you again for your help.