PSN-L Email List Message

Subject: Re: Article on gravimeters
From: Ed Thelen ethelen@........
Date: Fri, 12 May 2000 20:27:51 -0700

ChrisAtUpw@....... wrote:
> In a message dated 12/05/00 17:39:45 GMT Daylight Time,
> gjharris@............. writes:
> >  You would not believe what the gyros looked like!  Each one was a cylinder
> > about 5 inches in diameter and 8 inches long. The rotor was floated in a can
> > in a dense fluid. The pivots were small jewel bearings.
>     That sounds about right. And the rotor speed was controlled by two stages
> of centrifugal contacts..... which oscillated and needed precise setting.

Oh Nay - 400 cycle synchronous motors, with the
solid steel rotor (magnetizable by the stator current)
on the outside which supplied the angular momentum.

Honeywell used a quartz crystal oscillator with divide
circuitry to obtain a "fixed" stable 400 Hz.

The density of the fluid used to float the inner gyro unit,
(float to nullify off axis torques) was quite temperature
sensitive.  So, it took a warm up period (like 20 minutes)
 for the thermostatically controlled heater 
(in that can you mention) to get to the fluid to the correct
temperature (and density).  Some MIT cat (Draper?) 
got the floatation idea, and it was a winner.

All above circa 1957, gyros used for the Vanguard rocket.
(The guidance system worked, the propulsion system was
 designed to give low g's on lift off, 
 so that the Soviets would not think this was a war rocket.  
 Unfortunately, the marginally adequate lift thrust hiccuped,
 and the Vanguard was vanquished :-((


Where were we - oh - yes, pendulous gyros to
measure acceleration - yes - sorry -

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Larry Cochrane <cochrane@..............>