Re: [Flightgear-devel] Autopilot Bug/Feature

[Vivian M. <viv...@li...>]

Curt wrote

=20
> I think the simple solution here is to modify the autopilot config so
> the input is not from a vacuum driven heading indicator since you =
don't
> have one, but from a different property that you do have.

There is one - nearly - as I said orientation/heading-magnetic-deg. But =
it's
not derived from an instrument, and therefore has no supply, neither can =
it
fail, not does it have any error. Further, use of such a property will =
not
stop, AFAIKS, the generation of spurious and unnecessary instruments, =
caused
by incorrect initiation, and a hack to get around this. This looks
unprofessional.
=20
> The autopilot is designed to be very configurable in this respect and
> even though it can be complex, you can create a custom config for each
> aircraft that matches it's real world capabilities and design quite
> closely.

So it is. Except the existing Heading Indicator is quite inappropriate =
for
even halfway recent military or civil aircraft.

>=20
> Vivian Meazza wrote:
> > In the course of developing the KC135, I noticed that parts of the
> autopilot
> > function do not work in that model, copied from the B737 - the bits
> > described as vor/loc and app. Investigation showed that the cause =
was
> simple
> > - in JSBSim a jet ac does not have vacuum system. No vacuum - no =
Heading
> > Indicator - no Heading Indicator - no vor/loc etc.  So quick as a =
flash
> I
> > rustled up an electrically driven one. Simple solution? Wrong: when =
I
> tried
> > to implement a dedicated instrument.xml configuration for the KC135,
> using
> > the new Heading Indicator, the old one was still present (and still
> > inoperative). This is caused by xmlauto.cxx initiating before
> > instrumentmgr.xml, and creating the unnecessary nodes which it =
needs. So
> I
> > changed the initiation order. But by this time I realised that the
> simple
> > Heading Indicator we have is not what would be fitted to a KC135, or
> indeed
> > any jet ac since the '50s onward. We need what I would call a flux =
gate
> > compass (you might know a more modern term). This is more or less =
just
> the
> > property orientation/heading-magnetic-deg, but I thought that, for
> > completeness a proper flux gate instrument electrically driven etc,
> would be
> > nice. So I coded up one, and amended xmlauto.cxx so that it uses
> whichever
> > sort is configured and does not generate spurious ones.
> >
> > Now, I might have got hold of the wrong end of the stick here, and
> someone
> > may well know better. I intend to arrange the upload of these pretty
> trivial
> > changes at the weekend unless otherwise directed, or as I would have
> said in
> > a former existence UNODIR.
> >
> > Regards
> >
> > Vivian
> >
> >
> >
> > _______________________________________________
> > Flightgear-devel mailing list
> > Fli...@li...
> > https://lists.sourceforge.net/lists/listinfo/flightgear-devel
> >
>=20
>=20
> --
> Curtis Olson        http://www.flightgear.org/~curt
> HumanFIRST Program  http://www.humanfirst.umn.edu/
> FlightGear Project  http://www.flightgear.org
> Unique text:        2f585eeea02e2c79d7b1d8c4963bae2d
>=20
>=20
>=20
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