Alan,
Nice clean job.
I prefer not to run a thin wall one inch tube that far without an idler
in the center. However, the pitch system only needs a couple of pounds
of pressure when out of trim, and when the stab is trimmed neutral, very
little pressure is necessary to move the stab. We design our systems
for the worse case scenario, that is, full trim up the the max torque of
the trim motor and the bending moment of the thin wall tubing has to be
capable of taking the load plus a rather large safety factor (since it
is a control system) without bending or flexing. If the trim tube
should bend, it can jamb the flight control.
I prefer to put the trim motor where you did, but make a 3/2 ratio arm
to drive the tube via a tube clamp.
However, to keep a short drive tube, I would recommend installing the
new light weight servos behind the mass balance post using a two inch
extension from the torque tube arm (there are two holes there anyway to
mount .016 steel arms to). Use a 1/2 inch with .049 wall for the drive
tube (like the aileron tubes). The length of the tube should be about 2
feet.
Regards,
Bud Yerly
From: Alain Chabert
Sent: Saturday, April 11, 2015 1:05 PM
Subject: Re: Europa-List: Autopilot servo instalation
Hello,
Look at the solution I adopted from 330 hours and is much simpler than
the proposed mod.
Regards
Alain CHABERT
Le 11/04/2015 18:44, William Daniell a =C3=A9crit :
I have seen searching through the list that there are some
alternatives to the major surgery required for Mod 75 and 76.
For example I saw some correspondence between Raimo and Bob Gowing
connecting servo to the tail plane torque tube using a bracket. I
assume that the service is mounted on a fiberglass bracket mounted on
the floor ....
Could I prevail on anyone who has who has an alternative to the
official mods and which does not require major surgery send me a pic
please.
Many thanks
Will
William Daniell
LONGPORT
+57 310 295 0744
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