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From: "Hapgood, Matt" <matt.hapgood@wachovia.com>
To: "'lancair.list@olsusa.com'" <lancair.list@olsusa.com>
Subject: 360 pitch trim - too much??
Date: Mon, 15 Oct 2001 21:18:35 -0400
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X-Mailing-List: lancair.list@olsusa.com
Reply-To: lancair.list@olsusa.com

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
First Union Securities, Inc.

I have too much sensitivity in my pitch trim.  Way too much.  I thought I
could solve the problem by getting one of those little boxes that reduces
the trim servo speed.  No such luck.  Details:

360 Mark II tail and long gear
CG nicely centered
Mac servo pitch trim

If I just tap the pitch trim, it moves too much.  In fact, on the LED trim
indicator, it never moves from center.  This is in slow and cruise flight.
The trim "tab" is about 14" long by about 2 or three inches.  I think it is
the "standard" size.  I didn't build the horizontal stab or elevators - I
did that once (small tail), but decided to let someone else do round two.  I
think he followed the plan.

So I called the factory, and Orin said that I needed a different, longer,
attach bracket on the tab.  That would required more servo travel for the
same amount of trim tab movement.  That makes sense.  But my concern is that
the trim TAB barely moves now and it is TOO sensitive (about 1 cm deflection
either way seems like too much even at slow speeds).  Changing the trim
servo angles won't help that.  I am thinking the tab is too big.  What
thinks the rest of the list???

Thanks,

Matt


[I agree with Orin... a longer arm to actuate the trim tab would reduce
the throw and "de-sensitize" the trim tab.  Try making a new attach
bracket that's twice as tall as the current one.  (If the servo attach
arm is 1" long, make it 2" and reconnect the servo... your throw at the
tab will be cut in half.)  Try it during slow flight with the servo speed
reducer turned on first to see if you're heading in the right direction.
I'd reserve decreasing the area of the trim tab as the final alternative.

  <Marv>     ]


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