On 13 Oct 1996, Paul & Liz Atkinson wrote:
> Graham Clark wrote:-
> Would a car or yacht type compass do ? These also give an
> attitude reference for negligible cost !
>
>
> I dont know but I like the idea of using them as a cheap A/H. How do they
> perform when inverted? :-).
> If RMI do as they plan, my instument panel could consist of the Encoder and
> and
> a Skymap. What shall I do with the rest of the space?
>
> Paul Atkinson 237
>
>
> E-mail from: Paul & Liz Atkinson, 13-Oct-1996
>
>
Hello, all--please note that a mag compass will _not_ serve in
any way as "a cheap a/h." They're kept level by their own weight
suspended from the bearing pivot--i.e. in a turn they'll try to tilt to
what they think is the local vertical, not the true one. In fact, in a
properly coordinated turn, apart from some minor magnetic effects, they
should read "wings level" with respect to bank.
That having been said, their _is_ one particular mag compass that
_will_ provide some rudimentary attitude indication. It's Swiss and made
by the Bohli company, and uses an extremely light magnetic element (the
indicator is a red pith ball mounted on the end of a carbon whisker),
gimballed in three dimensions. It's tricky to use, but once you have
learned the technique it's good enough to have been banned in
international gliding competitions (since it allowed illegal cloud
flying). It's also expensive and quite bulky. Try some of the gliding
types at Dunstable or (Sp)Lasham (depending on season) for more info.
Peter Lert, A037
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