Noooooo...
It's not often I get stuck, but I am!
Got me an overpowered Y6. It's running 3.2.1, Y6B model. 11" CF props all round. rcx 2814-9 (800kv), on 6S. 420mm size, 2.8kg AUW.
It flies ok...as long as you don't yaw. It yaws too aggressively in one direction then took an eternity to stop, and barely yawed at all in the other direction. It holds level flight and heading no problem if you loiter. Pitch and roll are perfect. Punch outs are flat and level, but yaw to the aggressive side.
Props and motors are all on correctly. I think...
I took it home, thinking, "the logs will show the yaw disparity". But no - desired Yaw matches Yaw perfectly!...but that's impossible, because yaw was all over the place!
What is going wrong? What am I missing? Double checked the motors and directions. Logs attached...
Replies
Bingo!
Two changes, and it's fixed.
- 1147 top props changed for 1038
- Y6A config instead of Y6B
Yaw now locked and balanced, even under duress.
Downside? Hover throttle increased from 28% to 34% and the top end lunacy is now gone. It's still fast, but it's not the madman it once was. It's on prozac now. Oh well.
Since I changed them both at once (schoolboy error), I'll slap the 1147's back on the top, and see if it's still ok. Just so I know the exact change that fixed it.
The y6b is CW on top and CCW on the bottom; is it possible the top props are starving the ones below? It still won't explain how the yaw is matched.
Yes, radio setup completely standard with no offsets or curves.(taranis).
Mission planner shows pwm equal on both sides of centre.
"both sides" ?
You should see about same PWM for all motors while in hover and with a centered CG.
What you describe, sounds like it's already compensating near to maximum to hold heading, (that's why is spins faster one way, less the other)
If all motors are in vertical direction, recheck propellers and rotation direction, also - make sure they are not "upside down" (all should face "up")
Finally, you may have a very poorly performing motor, odd case with some damaged windings etc.. - so check thrust for each.
Well, the thing that comes to mind is if you have one or more motors on at a slight angle, so you have horizontal components in the lift vector. I had this and it comes close to what you describe.
What you can do to verify this is to measure the distance from prop tips on either side of the motor to a flat, horizontal surface. If there's even 0.5-1cm of difference between them, it can generate this moment around CG.
The other thought is simply the radio... did you configure some weird dual rate or other settings on the yaw channel? Should be able to verify this through MP.
If it's the radio, I'd expect that after a yaw operation, it would be quick to lock back in. So my guess is that it's something more mechanical and this issue with a moment being generated around the yaw axis due to misalignment of the motor with the vehicle's vertical, skewed props or maybe one motor not delivering its full power potential.