Help with trex 450 Apm

Can someone with experience take look my logs,problem is that i can’t get heli fly stable in fast forward flight.
When it gets up to speed tail starts jump up and down,ATT.DesPitch and ATT.Pitch does not track very well.


Is this a 450 Pro, or is it the 450L Dominator with a DFC head?

It’s Trex 450 Sport with flybarless head

OK, well the tuning looks reasonable, and it’s really hard to analyze the phasing of the severe pitch problem vs control inputs to tell if the autopilot is driving it or reacting to it. The software you are using is quite old and doesn’t have the advanced logging we got now. I think it’s reacting to it and “chasing it”, which makes it worse.

So the first thing I’d be looking at is mechanical issues like blade tracking, bent mainshaft (I’ve seen brand new ones factory bent), blade balance, and headspeed. 450’s like lots of headspeed to be stable, and the tail jumping up and down is classic low headspeed with these things. 2,900+ rpm is what they seem to like to run.

Thanks for your help Chris,i will try increase head speed.
Today i decreased H_pit_max and H_roll_max values to get approximately 8 deg of cyclic pitch,now i need wait for weekend to make test flight.

450’s are typically extremely responsive, twitchy little devils. It could be vibration causing the pitch bob too, but the old APM don’t log it. Being it’s not uncommon to have one be a little “touchy” I’d look at the mechanicals first like blade tracking and balance, and make sure the headspeed is cranked up. The 450’s really like headspeed because of the small rotor.