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Re: [ATM] water drive
> OK, here's an odd thought (and no, I haven't done the math on this). If
> the
> water is driving a tangent arm, we'd want the rate to change as the level
> dropped...
Take as an example a tangent arm drive turning an angle proportional to
arcsin(x), where x goes from -0.13 (radians! approx. -7.5 deg or 30 min of
travel) to +0.13. With exact speed near mid-travel (x~0), the deviation at
the ends of travel is 75 arcsec - slowing down somewhat to make the error =0
at end of travel means the max. error (a little more than halfway to the
end) is some 45 arcsec. Presuming my calculations were not too far off!
I'd like to think it takes a bit of effort before polar alignment errors
become less than this...
Nils Olof
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