input. It's quite different from the traditional designs that use the turn
coordinator or the attitude indicator to control the roll axis.
What really attracted me to the Digitrak was its simplicity. The
interface is about a simple and elegant industrial design. You can't
get more simple than a heading display and two buttons. Also, it is
kind of revolutionary in that you don't need all the usual expensive
and complicated instrumentation of the typical general aviation
aircraft to navigate. The minimum requirement is actually a Garmin 35
antenna that has a built in receiver and provides ground track and
ground speed. The Digitrak will follow whatever heading you enter into
the display using that data. I also like the idea of how simple it
becomes when you bring everything into the digital domain and drive
the flight controls with stepper motors. It's really fascinating and
offers a lot of potential for making autoflight possible on nearly any
aircraft (I can think of how it might apply to a Personal Air Vehicle,
which has to navigate itself or be very simple for an ordinary person
to operate).
Also, one of the stated features is that it does not rely on a turn
coordinator and as such makes claims of better turbulence handling.
This is one of the areas I am hazy on, how it actually works. It was
easy to model in MSFS, I just connected the heading display to the
heading but and to the GPS autopilot. That's cheating.
The Digitrak has a built in DG and a magnetometer, which I believe is
used to sync (correct automatically) the DG to the compass heading. It
also states the DG is slaved to the GPS, which I take to mean it can
make the same correction using the GPS or perhaps it only means it
syncs the DG with the selected heading. Apparently, you can fly the
heading by DG when there is no GPS signal. The modes are GPS NAV,
which keeps a heading with ground track data, a GPS flight plan mode
that automatically follows waypoints if the GPS sends a waypoint to
it, and the magnetic DG.
I would like to model this without using the turn coordinator as
input.
Again, I am long winded, but there are many oddities about this
autopilot that need pointing out. Thanks for the advice. I'll read it
and get back to the list.
Are you using version 0.9.8 or CVS?
I am using the 0.9.8 Windows XP binary.
Steve
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