[simpits-tech] Zero point on a two needle altimeter

[Gene Buckle]

I'm using a purpose built simulator altimeter.  I don't know what the guts
look like though as I've not had a chance to dig into it yet.

g.


On Sat, 26 Oct 2002, Matt Bailey wrote:

> Heh, good idea. But how do you tell where the needles are? Unless you
> put a sensor on the hour hand, which would give you 100,000feet (like I
> mentioned before), assuming the clock had all three hands. Are you using
> the clock idea in your F-15?
>
> 	-Matt Bailey
>
> Gene Buckle wrote:
> >
> > You guys are missing the obvious.  Buy a cheap battery powered clock drive
> > and drop the original motor out of it and drive it with a stepper motor.
> >
> > g.
> >
> > On Sat, 26 Oct 2002, Matt Bailey wrote:
> >
> > > Interesting ideas on this subject! One thing to keep in mind, the
> > > relationship of the turning of the hands of an altimeter is always the
> > > same, the hundreds needle always makes 10 revolutions per one revolution
> > > of the thousands needle etc. So you really only need one connection to
> > > the motor and sensor (perhaps on the hundreds needle, for precision) and
> > > just drive the other needles off that, using gears or pulleys. Also, if
> > > you had a way to measure the position of the ten thousands needle, your
> > > software would always know where that needle was and hence where the
> > > other needles are...only problem might be resolution since there is so
> > > much difference between this needle and the hundreds needle, for
> > > instance. But without having to count the number of revolutions for this
> > > needle, you would get a range of 100,000 feet. Quite sufficient for
> > > anything other than very high performance fighters (like the F-104) or
> > > spacecraft.
> > >
> > >       -Matt Bailey
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