On 11/2/03 12:05 PM, in article CHbpb.260660$6C4.185337@pd7tw1no, "Gary
Watson" cf104@ihate spam.shaw.ca wrote:

The dual AHRS/GPs updated types of systems work well in the slow movinn'
easy turning world of commercial air transport. I know the LTN 72, Carousel
IV spinning iron systems from aircraft such as the G-II and L1011 etc and
the RLGs are much much more reliable but this is not in the military
environment.

I was intersted to hear that the alignments would go "south" during the
catapult stage. Did air alignments work out ok as I realize you were getting
lat/long info from another aircraft but can't imagine having the time to
carry out the process.

BTW my interest is because I teach Nav systems to tech school students and
we were discussing INS and the need for a stable airframe for alignment. I
can now go back Monday and answer the question about aligning whilst the
aircrafme is moving. Thanks guys

Gary Watson



Gary and Foodog...

With regard to slow movers...
AHRS/GPS would be no problem for slow-movers in my opinion--whether UAV or
domestic air carriers. I wouldn't want to take one overseas--and couldn't
legally in the North Atlantic in RVSM airspace.

With regard to USN INS's...

Occasionally, the mechanical gyroed IMU/INS would dump on the cat when the
alignment was weak or due to some mechanical or electronic glitch. 1/2 of
the time you could IFA it and get it back. In my experience, the ASN-139
RLG INS doesn't care about the cat stroke.

The mechanical INS's would also build insidious, non-obvious
errors--occasionally until they'd dump entirely. Then you could IFA them if
you had the time/airspace.

The RLG fails fast and fails totally if it's broken. It's seldom that
you'll get it back once it fails--unless you caused the failure yourself
(due to incorrect initial coords during the alignment or bad SINS data).

Accurate data (3-axis) is important for many things, but most importantly
for transferring nav data to weapons--especially some of the newer more
complex stuff.

--Woody