Actually, field rotation is a very complicated function of altitude and azimuth. For example, exactly at the zenith, the rotation rate is infinite. Also, if your field is circumpolar, the rotation stops and reverses at two points in its 'orbit' around Polaris (its eastern and western most points). The one rpd thing would only work if your field were centered exactly on the north celestial pole (because then the altitude and azimuth would remain constant). We derived the whole thing in my astrophysics class at the U (rather nasty derivation, I needed help from the professor to figure it out). Greg --- Chuck Hards <chuckhards@yahoo.com> wrote:
Hi Bill:
Of course any clockwork mechanism can be designed to be powered by a falling-weight drive, but it would be hard to beat a motor/gear driven unit for compactness & simplicity.
C.
--- bill biesele <xmix@biesele.net> wrote:
If a field derotator is a 1 rpd drive couldn't one be built with a pivot and counterweights? Axis of pivot would be parallel to optical axis, counterweights would hang down to drive rotation at 1 rpd by gravity.
Wouldn't want to use it in a wind, but would it work?
Bill B
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