Re: [ATM] Telescope direct drive

[Andy Saulietis <iss@pvtnetworks.net>]

Re direct drives,

>>Telescope direct drive may now be possible using a new kind of piezomotor.
>
>
>The issue with these motors has always been cost.  Last I checked the cost 
>of a motor far exceeds a typical drive setup.
>
>Also I wonder about the dynamic stability at low rates of motion.

We had *very* accurate low (and high) speed direct drives (magnetically 
coupled with
air bearings) gyro test tables since the 50's. Rate stability was achieved by
using a rotor with a large mass..one of our lab guys converted a surplus rotor
assembly into what had to be the best 33 1/3 RPM record turntable 
*ever*..you could
spin it up to speed and shut off the power, the thing would maintain RPM
for hours via inertia..

Re the cost..the good news is that radar stealth coatings are now
available for private automobiles..the bad news is that it costs
$400M per car..<g>



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