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How to handle SAFE wanting to nose-down?

#1
I’ve held the UMX Ultrix as flat as feasibly possible when connecting power on the field. Upon hand-launch, the trajectory favors the ground. Constant elevator deflection required, and i’m new to 4-channel (experiences in powered glider w/o aileron only). I managed, although broke a prop on my first 10 seconds of SAFE mode deactivated. After quick repair, managed to fly with some acrobatics (rolls and spins; no flat spin but variants of the ‘blender’ basically), and land safely.
The problem is that the plane, on SAFE mode, wants to nose-down. I’m holding it as flat as I reasonably can when connecting battery. How to deal with this? I think trimming would be overridden by SAFE mode gyroscope ‘impression’ of level flight... What do you all do to avoid this? Is it my CG? Or, not “level”-enough when I connect battery..?
I can fly it, even with SAFE off (although winds inevitably force me to use SAFE to recover), but i’d prefer if my SAFE switch correctly understood “level” flight...
 

Bricks

Well-known member
#2
The plane does not have to be level when plugging in the battery level flight is programed into the AS3X receiver. Which transmitter are you using? When binding did you initialize SAFE buy pulling the bind plug after receiver is in bind mode before turning on your transmitter and binding? Make sure the receiver did not come loose and moving around. Take all your trims out from the transmitter turn everything on and see what the elevator does when the plane is leveled, move the plane around to make sure all corrections by the AS3X are working in the right direction, let us know what you found.
 

FDS

Well-known member
#3
The UMX models safe board binds differently. You initialise it when it’s on the ground by plugging it in, then putting it flat on the ground. It beeps when it’s set.
You can try two things, one lift the tail a bit when you initialise it, two trimming it out.
To trim the control surfaces put it on a table level, switch on, then turn safe off, in “expert” mode. Now look at the elevator trim when static, make sure it’s not up, trim until it’s flat.
Then switch safe on (again with it still level) and see if it puts the elevators down automatically. This way you can see if it’s the computer doing it or the trim.
If that makes no difference to launching then try switching it off to take off, either in intermediate where it doesn’t fully self level or expert where you will have more control deflection.
Also does applying more throttle lift the nose? You may be trying to take off with insufficient thrust.