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Alex,

I agree that Cel Nav was used to check/update the INS units.  I believe the 
frequency might have been as low as once every 14 days.  If you read the 
descriptions of the units the U.S. Navy used in the links I provided, they 
probably exceeded what is available publicly today.  They also had four 
units, not a single unit.

Fred Hebard



On Apr 12, 2012, at 1:43 PM, Alexandre E Eremenko wrote:

> 
> Greg,
> Thanks for this interesting piece of evidence:
> 
>> the extremely stringent standard required for launching nuclear-tipped 
ballistic missiles after being submerged for long periods without position 
updates from offboard sources. The WSN-7 and WSN-7A RLG-based systems require 
updates from the global positioning system (GPS) every 14 days."
> 
> Given that a modern system (which is for sale now; I gave a link in
> one previous message) does 1nm/day, and assuming that the performance
> of the INS is
> the same, we conclude that the "extremely stringent standard"
> is about 14 miles:-)
> 
> Which is quite possible, because MODERN ballistic missiles do not
> rely solely on INS, but use Cel Nav (like space stations), a sensor
> which catches stars and possibly planets and/or sun by its sensor.
> But this sort of Cel Nav is probably out of the list scope anyway:-)
> 
> It still seems to me that Cel Nav was the most accurate and universally
> available method for checking INS until the satellite era.
> 
> Alex.
> 
> 
> 
> 

   

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