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Toilet Bowl Wobbles - Unflyable
#1
Hi all,

Hoping you will be able to help me with this issue I've had for a long time.

My quad started as a KingKong 210GT RTF. I believe the issue first started when I flashed from the stock cleanflight to betaflight. Basically, my quad became unflyable with huge toilet bowl wobbles on take-off. Initially, I thought it was a hardware problem so have changed FC, receiver and frame - with no change.

After research, I found that others (namely user: wingsfromheaven) had the exact same issue after upgrading from the stock cleanflight. https://forum.banggood.com/forum-topic-190548.html

So, my question is why can I not use the latest betaflight? Shouldn't the stock PIDs be good enough?

Thanks in advance, all.

Kind regards,
#2
I'd guess it's down to the very old ESCs which don't even support OneShot125. Betaflight expects reasonably modern hardware and works best when it can run at high gyro sample speeds and with fast loop times. I don't know anything about the flight controller that comes with this craft but it's either a CC3D clone or an SP Racing F3 clone. Neither of these are recommended flight controllers for Betaflight. The CC3D only has an F1 processor and the SPRF3 has a slow 6050 IMU connected on I2C instead of SPI. So, neither flight controller is a good match for Betaflight and the ESCs are a very bad match.

Flashing new firmware onto this quad is a perfect example of why "if it ain't broke, don't fix it" is such good advice.

The term "toilet bowling" is one that is used when taking about GPS enabled quads. It's how a GPS quad flies in circles in GPS mode because the quad's magnetometer is not correctly calibrated or is receiving lots of interference and the flight controller can't properly work out the craft's heading.

Large wobbles when in flight are not the same thing and are normally caused by the PID settings being too strong and causing the flight controller to constantly over-correct.

I'd suggest you go back to Cleanflight 1.12, reload the old PIDs and settings so that it flies properly and save Betaflight for your next quad which has hardware that fully supports it.
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#3
Could this be due to the ESC protocol running slower that the FC looptime? Might lowering looptime/sample rate help?
Or just a case of BetaFlight saying
"I CAN'T WORK UNDER THESE CONDITIONS"
Windless fields and smokeless builds
[-] The following 1 user Likes Tom BD Bad's post:
  • unseen
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#4
If what unseen says about the escs is correct, then that could mean they don't even have active braking, which could be the problem - motors take too long to brake and thus keep winding up on the smallest of errors...
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