DJI F550 / NAZA Oscillating during vertical decent.

[Rick~K]

This is the only time the 550back does this is when I go into hover and then decending. At times it gets pretty bad, I have the NAZA mounted center and tried different gains. Anyone had this happen and whats the cure.
Thanks!

 

[Bowley]

Rick, MR's just do this to varying degrees because your descending into disturbed air, its basically moving into it own prop wash. I try to treat the MR like a gliding plane when descending if I want to keep it from flapping about.

 

[mailman35]

yeah i had the same dropping prop sizes fixes it slightly, or slowing the decent even more, or the easiest is a nice bit of forward motionand it comes down so smooth

 

[Dewster]

Yes, agreed. It's the rotor wash. A slow decent, or a slow glide to landing will reduce the effect of the rotor wash/turbulence. I flew mine yesterday and experienced the same thing on my WKM. I'm using 10x4.7 APC props on an Xaircraft DIY hexa. I'll have to try smaller props one day to see how it flies/handles.

 

[Bartman]

i think it also has something to do with the fact that the motor response is tuned to be only so aggressive at maintaining control. in descending flight though the props are slowed to allow the descent so the motors don't have the same grip on the air that they would in level or climbing flight. Maybe if the FC were able to up-tune itself in descending flight to be more aggressive the wobbles would go away.
maybe if someone has time try mixing two channels in the radio, one would be throttle and the other would be control gain. when the throttle goes below hover the gain would increase ever so slightly. i'd love to see the outcome of that experiment!
i've got higher pitch props on the bottom motors of my coaxial quad and it has helped to almost eliminate wobble except in really fast descents.
Bart

 

[Rick~K]

Thanks Everyone for your reply. All are very good answers and make since. I'll slow my decent more to keep wobble down, where I fly off my back deck I have to do a vertical to get through the trees. :frog:

 

[Dewster]

No problem Rick! lol! I have to navigate over some trees too when I takeoff and land from my deck.

 

[Gunter]

Deffo don't come straight down, but descend at a slight angle and that will go away. It's just flying into dirty air that does it...or try descending slower.

Gunter.