Re: ATR-42/72 in icing

From:         shevell@leland.stanford.edu (Richard Shevell)
Organization: Stanford University, Dept. of Aero/Astro
Date:         02 Dec 94 02:48:58 
References:   1 2
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In article <airliners.1994.1727@ohare.Chicago.COM>,
shevell@leland.stanford.edu (Richard Shevell) wrote:

> In article <airliners.1994.1713@ohare.Chicago.COM>, David Lednicer
> <dave@amiwest.com> wrote:
> 
> > 	My suspicion is that as the balance horns ice, a change in 
> > aileron hinge moments is produced, and hence, control load ...

> Dave, I think you are on to something there.  My first reaction was to
> think you were in a time warp talking about balance horns.  That was a
> normal design procedure in the 20's and 30's.  Even the DC-3 did not use
> horns.  Aerodynamically balanced control surfaces on transports from then
> on used an overhang ahead of the hinge line for balance ...

Pursuant to an E-mail request, balance horns are portions of a control
surface that extend spanwise beyond the tip of the fixed surface to which
it is attached, and are forward of the hinge line.  The purpose is to move
the center of pressure of the surface, like a rudder or aileron, forward
and reduce the hinge moment that must be applied to hold the surface in a
deflected position. They were frequently used on early aircraft including
many biplanes in the 20's and the Ford Trimotor.
-- 
Richard Shevell
Email: shevell@leland.stanford.edu