Re: A 777 with four engines.

Date:         23 Aug 98 14:34:00 
From:         Mary Shafer <>
Organization: NASA Dryden Flight Research Center, Edwards CA
References:   1 2 3 4 5 6 7 8 9
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andyweir <> writes:

> In 1995 NASA, I think it was, demonstrated a propulsion control
> software package called PCA that took the guesswork out of
> differential thrust. It simply plugged into the FMC or FADEC of an
> MD-11. Don't know the current situation, but I believe NASA
> expressed disappointment in the lack of interest in the package from
> airlines. Presumably, the software's principles are universally
> applicable and could be adapted for any big jet with FMC and/or
> FADEC. I wonder what became of it?

It's NASA DFRC and they're going into a simulation using one of the
Ames simulators fairly soon, using airline pilots as subjects.  It
works by picking off the pilot's command from the cockpit controllers
and using this input, with a simple control system, to drive the
engines so that the plane responds in something approaching the normal
manner.  Being a backup mode, of course, degraded performance is
acceptable, so there's no need to make this system fly as well as it
does in the primary modes.  Flying by using the yoke (or sidestick) in
the usual way is much more natural than trying to do it with the
throttle levers.  (Actually, Al Haynes did use the yoke, with Denny
watching his inputs and manipulating the throttle levers to produce
the "commanded" response.  As a result, Haynes had not ever looked at
Denny; the first time he saw him was at the SUX hospital, when he was
taken to his room, and Haynes was concerned that he wouldn't know
which one was Denny if there were two patients in the room.)

I can't find the PCS briefing charts right now, but there have been at
least a dozen incidents of pilots using thrust-only or
thrust-augmented flight path control to save the airplane.  These
aren't all airliners, though; one was an F-14.  The various technical
papers on PCS, written by Frank W. Burcham and C. Gordon Fullerton, are
on the DFRC Web page, at
in the link that leads to technical reports.  A description of the
current status can probably also be found there, in the links for
current research projects or press releases, I think.

Mary Shafer               NASA Dryden Flight Research Center, Edwards, CA
SR-71 Flying Qualities Lead Engineer     Of course I don't speak for NASA                               DoD #362 KotFR
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