Takeoff Trim Issue

[Taildragger831]

The T.O. recommends 1-3 units of nose down trim to be set before takeoff. As I am rolling down the runway the trim slowly returns to the neutral trim setting. This occurs even if I put the trim full nose down, it still returns to neutral before liftoff.

Any help would be great, thanks!

[Alvaro]

Dynamic pressure is moving and repositioning the stabilators bellows as part of the control feel and trim system. The steepest gradient of the system displacement is located at lower speeds where a higher trim sensitivity is needed / allowed. At high airspeeds, out of trim conditions with speed changes will be equally noticed but control feel and trim sys displacements will be barely noticed in the trim indicator.

So, not a bug, normal system behavior.