> ... > If a FDM wants to use obscure units internally (e.g. because the
> > developers are use to them) that's their choice. But when we have
> > very universal data that a lot of people need (users, panel
> > programmers, ...) we should use an international standard.
>
> I agree with the principle, but note that the aircraft panel
> instruments give the altitude in feet, not meters, the altimeter will
> be calibrated for inches of mercury, not pascals, and the airspeed
> will be in knots (or possibly statute mph), not kph -- using SI
> internally will force a lot of conversions. I'm sure that there exist
> SI aircraft panels somewhere, but I have not yet seen photos of any in
> general aviation.
>
David,
The only place that I know of that manufactures aircraft (or at least did
routinely) with SI based instrumentation was the old Soviet Union. Some of
their aircraft either sold to customers, or operating outside the SU were
involved in at least two mid air collisions (IIRC, between heavies in India
and off western Africa). This was thought at the time to be due to confusion
over unit conversion, either in the cockpit or by the ATCs involved. Maybe
somebody can recall these instances with better accuracy. Either way, history
condemned us to English units.
At any rate, might we introduce a configuration line in the set up files that
alerts the program that all following units are SI instead of English? Ditto
access members that are known to report/set data members/parameters in SI
instead of English unit values? This might make dealing with airframes like
some of the older Russian designs a bit easier and less error prone.
Regards,
Charlie H.
--
"Madam, there's no such thing as a tough child- if you parboil them first for
seven hours, they always come out tender."
- W.C. [William Claude] Fields (1879 - 1946)
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