REFLECTOR: Trim authority

[Al Gietzen]

John;

In that case the bending force would be strongest at the point where the
spring makes a 180 turn and least at the ends.  Or am I missing something?

 

On further thought I’d say I really don’t know what the stress distribution
is.  The sides of the U are also in bending stress; and depending on how it
is connected to the torque tube bracket (wedge shim, or not), and the trim
postion; that leg is also subject to a bending moment as the TT rotates.
For me the uniform width has worked fine.

 

Why do the best landings occur when there is no one in the right seat to be
impressed by it?

The landing characteristics are almost always worse with a passenger on
board:-).

 

Al

 

 

John;

The width of the ? trim spring in mine is about 1 ¾” – uniform width to
avoid concentrating bending stress in one area.  Just guesstimating; I’d say
with full down-trim (elevator up) it takes 25+ lbs stick force to pull
elevator to about 1” down – which is about what I’d need for landing.
Similar in the other direction to get about 1” up. 

Hope this helps.

Just went flying around a bit today – with our current slightly easterly
flow, temps mid 70’s, smooth, crystal clear for 50 miles. Did a perfect
landing, I’d rank in the top 5 ever - makes you love your airplane. 

Al

 

Al,

Thanks.  Avoiding concentrating the bending stress is also what I have in
mind with my suggestion to vary the spring width.  It's been a while since
I've looked at it, but as I recall the spring is a "U" shape, with attach
points at both ends.  In that case the bending force would be strongest at
the point where the spring makes a 180 turn and least at the ends.  Or am I
missing something?

 

Why do the best landings occur when there is no one in the right seat to be
impressed by it?

 

John

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