LS-4 Trim Lock coming loose with stick deflection?

On 2/1/2011 7:57 AM, Andy wrote:
On Jan 31, 9:58 pm, wrote:
It's not an "known issue". It's the design. I have an LS1f and it has
a similar if not identical trim control. It just applies friction, so
it will let go a little when you apply enough forward or aft movement
on the stick. The slipping prevents the spring pressure from fighting
against you for larger fore/aft movements while still keeping the
stick neutral for the small ones. This friction control especially
comes into play each time you transition from thermalling to glide or
vice-versa. It will move when you push or pull harder during those
transitions instead of trying to resist your stick movement. It still
takes a slight adjustment on the trim to neutralize completely after a
transition, but it gets the trim going in the right direction by
slipping and following the stick somewhat. Locking it down would cause
considerable spring tension and will fatigue your arm. I've tried that
and it's way nicer to fly if you adjust it correctly so it moves. It's
an adjustable friction, not a "lock".

Dave

I find it hard to believe that a trim system that allows uncommanded
changes in the stick force gradient could ever have been
certificated. Does anyone else believe the trim system was designed
to slip in this way? Are any other gliders designed to have a trim
system that slips?

Andy
The trim on my LS-4 stays put through full for and aft travel of the
stick when the trim is centered. When the trim is at it's for or aft
limit the trim will move slightly with full deflection in the oposite
dirction. However our clubs LS4's trim has significant motion in the
trim without full diflection. I find my self holding the trim knob to
keep it from moving to keep the glider trimmed. Otherwise, I am
constantly retrimming the glider while thermaling.

Wayne