REFLECTOR: Elevator Trim Spring

[Pat Shea]

Steve,

Actually, if the sparrow strainer is installed as the
factory prescribes, it makes the trim situation WORSE
at cruise. It has a negative angle of attack relative
to the elevator and is an upside down airfoil. Both of
this work to pull the trailing edge of the elevator
down at high cruise. Since the Trialing edge of the
elevator is above the in-trail position at high
cruise, the sparrow strainer is working against you
the faster you go. Of course all this would be very
undesirable without a pitch trim system - the good
news is we have one.

The purpose of the sparrow strainer it to pre-load the
pitch trim spring more (by making it work harder) at
higher speeds. This helps stabilize the plane by
increasing the pilot force required to move the
elevator at these speeds. This increased pre-loading
also increases the amount of external force
(turbulence) requires to induce a pitch change.

I know you changed you sparrow to be an aerodynamic
trim, but that is a completely different arrangement.

Pat  

--- steve korney <s_korney at hotmail.com> wrote:

> 
> Guys.....
> 
> The sparrow strainer takes care of the trim in
> cruise and top speed...  If 
> it's set right...
> 
> 
> Best... Steve


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