XClass Drone Tuning Analysis & Advice

[@johncgibson4720]

Appreciate this line of work. I use Betaflight for my 13 inch prop 250 gram FPV helicopter. I was skeptical about any pro looking into helping crafts with 13+ inch propellers. I am amazed you are here handling x-class craft, which often have 13-inch props, crash and the low pass filter is set at 50 hertz, exactly the same as my helicopter's setup.

[@chrisbee5481]

Hey Mark, I have a 7" LR build. With your preset it flys nice with a 300g battery. As soon as I put on a heavy 600g battery, it has lots of low throttle oscillations. Any idea what to do? THX

[@uavtech]

Increase PIDs (Master Slider) some or Reduce the Drift-Wobble slider. At low throttle and the heavier battery, it is losing motor authority to keep it steady. Make sure on 24k PWM (48k is ok, but not as good for low throttle authority). If only on a throttle chop, increase the Anti-gravity gain a bunch.

[@fpv_am]

4:14 dyn notch even with q=100 can never be as powerful as static notch. My apex has 215hz resonance with power of 0dbm which is a lot!!! By adding a static notch 170-215hz it jus goes away, wheareas sith dyn notch q=100 I get the samd latency and a lot more noise. Also, what if I need a 2nd dyn nitch q=500? I cant do that, the q factors have to be the same! So strong frame resobances should be targeted by a static notch!

[@patrickt2598]

You are correct. A static notch is a great tool for alleviating a strong frame resonance. There’s no need to use a dynamic notch to target a static resonance. But never, ever, ever have a static notch beginning at a value as low as 10 hz!! This will cause extreme gyro delay and will induce oscillations like those seen in this video.

[@BikeGuyFPV]

So are we not going to talk about adjusting the i-term relax cuttoff and dropping it down? In BF, it recommends for xclass rigs to set cutoff to 3 or 5. I-term is evil on a large rig like this from my experience tuning up xclass rigs over the years.

[@uavtech]

yup, for sure if you have bounceback!! But i-Term Relax doesn't activate for wobble.

[@BikeGuyFPV]

​​@@uavtech I've had and have seen other xclass rigs run away on people after doing a hard snap flip is why I mentioned it.

[@uavtech]

yeah, I-term is a bitch on big rigs - like you said - because they lag the controller so much. Big moment of inertia.