No GPS signal? No problem...

[M61A1]

So far , so good lol

That's what all the deseal-reseal guys say.

 

 

[dazza 38]

That's what all the deseal-reseal guys say.

I worked in reseal deseal, but only for about 2 months.Couldn't wait to get out of joint.

 

 

[M61A1]

I worked in reseal deseal, but only for about 2 months.Couldn't wait to get out of joint.

Did your ever run into Curls? I don't know what he was like before deseal/reseal, but he was bad afterwards.

 

 

[dazza 38]

Did your ever run into Curls? I don't know what he was like before deseal/reseal, but he was bad afterwards.

I don't recall that name, but it was a while ago.

 

 

[M61A1]

I worked in reseal deseal, but only for about 2 months.Couldn't wait to get out of joint.

I did 2 weeks on one aircraft we had that leaked a lot during the eighties, can't say I enjoyed it. I worked with Curls at wings section, he was ex-deseal, a very strange man. I used to wonder if he had a predisposition to some sort of psychological issue, before his time in deseal, or whether deseal was wholly responsible for his screwed up mind. He used to get very aggressive about small things, yet not care about other thing of similar importance, I was always surprised he could actually light a smoke, because his hands shook so much, I don't think the flame stayed on it long enough.

 

 

[dazza 38]

I did 2 weeks on one aircraft we had that leaked a lot during the eighties, can't say I enjoyed it. I worked with Curls at wings section, he was ex-deseal, a very strange man. I used to wonder if he had a predisposition to some sort of psychological issue, before his time in deseal, or whether deseal was wholly responsible for his screwed up mind. He used to get very aggressive about small things, yet not care about other thing of similar importance, I was always surprised he could actually light a smoke, because his hands shook so much, I don't think the flame stayed on it long enough.

I just pulled out my RTE- I worked in Reseal/Deseal from 21 Jun 93 and then late Jul 93(only one month ) I was then transferred to AMS wing section until Jun 95 then I went to Pavetack.

 

 

[dutchroll]

We had a single Litton 72 inertial nav system on the old C130H (before ring laser gyro INSs were made) during the 1980s and it would fly you reliably for 9 hours across the ocean commonly being only single-digit miles off track when you eventually got back within radar or navaid coverage, and generally within 5 miles or less which was very comfortably within its stated accuracy limits. This was a pure conventional gyro driven INS with no external position inputs (though you could manually update it).

 

The old F-111 INS powered by hamsters running in rotating cages was very early INS technology and was very susceptible to drift, but the Navs would update it often from radar fixes. Through the 70s, 80s and 90s INS technology improved exponentially, progressing through to the ring laser gyro systems, then the GPS updated systems. We got the ring laser gyro Litton 92s on the C130E in the 90s to replace the doppler and omega, and they were excellent, again usually needing zero updating even over flight times of 9 or 10 hours. The big thing about ring laser gyros is that there were no longer any moving/spinning parts, so reliability was a huge improvement and the position accuracy and drift was more accurate still. In fact the only time I recall ever seeing a Litton 92 updated from a radio navaid fix, it actually introduced a larger error than it started with and we had to quickly flush the update!

 

On the Flight Management Computer pages in a modern jet you can view the IRS data including the raw INS positions, the GPS positions, and the "mixed" or final calculated position based on all available inputs taking into account relative accuracy (which usually corresponds exactly with the GPS position, unsurprisingly). The raw INS position without GPS inputs is generally extremely close, and the drift rate is normally only a few tenths of a nautical mile per hour even though it is allowed to be considerably more than this.

 

Inertial Navigation Systems are actually dead-reckoning systems and have been highly accurate for many years now. What we are seeing here is the result of the increasing miniaturisation of electronics. So instead of a large black box sitting on a big avionics rack beneath the cockpit sucking large quantities of 115V AC power, we're seeing the same stuff on a single chip!

 

 

[Dafydd Llewellyn]

I installed the first Honeywell Lasernav INS sold outside the U.S.A. (serial No 15) into the CSIRO F27, VH-CAT, in about 1982. It navigated the aircraft from Tamworth to Sydney - without an Air Data System, i.e. totally by dead reckoning - with a final error of about 50 yards. (we started from a surveyed reference point at Tamworth, and used the aerodrome reference point at KSA as the basis for determining the error. That was the very first ring-laser-gyro INS. It cost $185,000 in 1982; it was roughly 500 mm x 300 MM x 150 mm and weighed about 25 Kg. Nowadays you can purchase miniaturised GPS-updated

 

INS packages like this - and they can also be used to keep a "virtual reality" moving-map image aligned with the horizon. Not quite as accurate as the Lasernav, I expect.