Re: Tristar FMC

From:         pete@ide.com (Peter Coe)
Date:         21 Dec 94 02:17:41 
References:   1
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In article <airliners.1994.1783@ohare.Chicago.COM>, ecla@world.std.com (alain
arnaud) writes:
>
>	As I recall, the L1011-500 had an active stability system, which
>	meant that the aircraft was basically unstable and required computer
>	control of the ailerons for safe flight. In the late 70's this was
>	way ahead of anyone else in the industry was doing and certainly
>	a precursor of the active controls in the Airbus family and closer
>	to Lockheed in the F117.
>

Nope.  The 500 had longer wings than the other Tristar models, but to save
weight the wings were not substantially strengthened.  To be able to deal
with the added stress the longer wings caused, the FMS had Active Gust
Alleviation (well it was called something like that).  This used the
ailerons as flaps to reduce the wing load in the event of turbulance.

The first 500's were delivered without the wing extensions, because the FMS
had not been finished.  BA sent back a couple to have the extra length put
on, and the FMS to be extended.

One respect that the Tristar was quite advanced was that it was delivered
with Cat 3b landing capability from day one.  BEA (British European Airways,
one of the airlines that went on to become British Airways), required this
capability for the northern european winters.  I think the Tristar was
cleared for Cat 3c, but no airports are!  Anyone know what the difference
is between the categories.  3c is zero/zero, and 3b is something like
50feet vertical/200 feet horizontal, but I'm not really sure of the figures.

The only time that a landing has freaked me out was a cat 3b landing
when the first thing I knew we were on the ground was when the thrust
reversers and brakes kicked in.  I didn't feel the touch down, and as I
was over the wing, the visisbility was such that I couldn't see the
ground.

Very Very impressive.  I really miss the Tristar.


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