Re: Stall Warning Systems on Commercial Aircraft

From: (Greg Wright)
Organization: Boeing
Date:         24 Apr 93 09:28:42 PDT
References:   1
Followups:    1
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In article <airliners.1993.357@ohareChicago.COM> (Civ Daniel G. Sharpes) writes:
>  I'd like to get some info on how the stall warning systems on various
>commercial big airplanes (and the biz-jets, too) work.  What sort of
>anticipation is included?  How often do nuisance warnings occur?  How
>were nuisance warnings eliminated?  Do the systems key on velocity and
>aircraft configuration or do they track alpha?

 Alpha vane and configuration are the main trips for the stick
shaker.  For each configuration the plane could be  in there is an
assorciated trip vane angle that the stall warning computer uses
to activate the stick shaker. On the newer stall warning computers,
mach effect on CL is taken into account to help reduce the needed
built in conservatism.  There are several smaller issues having
to do with stick shaker such as taking into account pitch rate 
effects on the vane angle but Alpha vane and the current plane
configuration are the two biggies.

 ________Greg Wright____________     High Lift Development 
|  |    747/767 Aerodynamics 
|       |                             
|____uunet!bcstec!gregory_______|               NOT A BOEING SPOKESPERSON.