"Paul Lonsdale" wrote in message
...
In article , Brian Reay
wrote:
some systems rotate the
gyros on a tourbillion like mechanism but these defeat one of the
objects
of a 'strapdown' system).

Ah the good old "Carousel". That was the model of INS that had ovens for
the
rate gyros that ran at 69 degrees F. I think Concorde may be the last
British Airways aircraft to use these, all the rest use IRS with laser
gyros.


I'm not familiar with that particular INS but the technique was (quite)
widely used. My background isn't on the civil a/c side but I'd be very
surprised if many civil a/c were not using a LINS these days- often as not
with a coupled GPS. The big US companies (Litton, Honeywell, etc) saw the
potential and threw $ at the problems. The base cost of a LINS tumbled and
the low maintained cost did the rest. I had a tour of LINS manufacturing
facility back in 1986 and they were already starting to treat LINS systems
as a commodity product (ie built to stock not order)- almost unheard of at
the time.

Prior to this there were some amazing techniques used to make gyros- my
favourite (although I never worked on them) had a solid 'ball bearing' which
was held electrostatically and rotated at high speed. I forget the details
now but, when I learned of it (in the early 80s I would think) it seemed
almost too clever to be true.

The advent of the 'cheap' RLG (ring laser gyro) saw off some interesting
techniques which were replaced by things 'without eye brows' ;-)


--
73
Brian
G8OSN
www.g8osn.org.uk
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