Re: Airbus Gust-Load Alleviation systems

From:         "BRAD GILLIES" <bradg@io.org>
Organization: Internex Online (io.org), Toronto, Ontario, Canada
Date:         31 Jul 96 12:29:41 
References:   1
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Martin <m.fiddler@staffs.ac.uk> wrote in article
<airliners.1996.1447@ohare.Chicago.COM>...

> I remember attending a lecture on the A320 wing, and we were told that
> it, and the A330/A340 wing, incorporated gust-load alleviation systems.
> Assuming I remember/understood correctly: a g-force sensor senses that
> excessive turbulence is causing too much stress on the wing.  The high
> loading is at the bottom of the drop, when the wings have to take the
> inertial load of containing the downward momentum of the fuselage when it
> stopps dropping and re-starts normal flying.  The GLA works by immediatly
> opening the wing spoilers/(lift dumpers?), reducing the sudden load on
> the wing and bringing the maximum bending moment on the wing down to a
> lower level. The guy said it works well (in reducing max bending moment)
> but the passengers percieve that the turbulence is worse than it is, due
> to the wing's reduction in lift during the downwards phase.
>
> So, is there such a system as I have described?

The A320 does indeed have such a system.  The LAF (Load Alleviation
Function) Unloads the stresses on the wing by momentaraly deploying the
Flight spoilers and deflects BOTH Ailerons upward.  The function is so fast
that it is hardly noticable.  I do not think that it makes the turbulance
feel any worse though.  The function seems to work very well.
Note: The L-1011-500 has used a similar system for many years it is really
nothing new.

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	Brad GIllies	Bradg@io.org
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