Question for RW carrier pilot

[Shack]

Im intrigued about the INS Carrier Nav mode of the INS. Gyros in ground alignment mode, have to be absolutely steady in order to correctly align. How does Carrier movement become compensated for in a carrier based INS system that's constantly sensing motion, for alignment purposes?

thanks !

Edited June 27, 2018 by Shack

[RuskyV]

I wonder if it connects to the ships INS to get position data rather than solely relying on GPS. Be interesting to find out.

[Papa Spardy]

I wonder if it connects to the ships INS to get position data rather than solely relying on GPS. Be interesting to find out.

 

It does. There is an actual cable you can connect from the flight deck to a port in the nose wheel well of the 18 if doing it wirelessly doesn't work.

Edited June 27, 2018 by Papa Spardy
Typo

[lemoen]

It has to connect to the ship's INS, GPS can't give you good roll and pitch information without having at least 3 antennas and even then it won't be as good as the INS. GPS altitude accuracy is poor, in addition. Heatblur has a post about their INS implementation that explains a bit about this stuff.

[TheSkipjack95]

For the Harrier, there's a Sea INS ( SINS ) cable you need to plug in to be able to align in SEA mode. I just don't know how it works, I assume it must be feeding the ship's position into both N and E lanes of the INS to feed the correction loops while the gryos warm and spin up.

 

If you're really bored I can suggest watching this series of vids on INS systems

https://www.youtube.com/watch?v=kZBgRN_jUSo

[RuskyV]

Interesting, is the alignment speed quicker then if you are plugged into a ships INS?

 

If i was to take a guess i would say yes it is?

[TheSkipjack95]

Could be, since you would just be waiting for the mechanical side to warm up.

[Flamin_Squirrel]

This is something I don't get; modern aircraft, (the F/A-18 included I believe) use laser ring gyros, so what moving parts does it have?

[Gunnars Driver]

This is something I don't get; modern aircraft, (the F/A-18 included I believe) use laser ring gyros, so what moving parts does it have?

 

No moving part but some INS/IRS systems measures the eart rotation to find the latitude by it self. For this the A/C needs to be stationary.

All INS/ IRS has to perform an alignment after the INS/IRS is powered on. For this the land based way is to measure earth rotation etc. This cant be done on a moving ship the regular way, because the A/C moves (position, course, roll and pitch) changes during this face.

Some A/C can still perform this task by themself, witouth connection to the ship, but not all.

 

[Edit]I can add that the own-system-alignment takes longer time on a moving ship, so the connection to the ship, getting information should shorten the alignment phaze on ship operations. So thats the reason for feeding the aircraft from the ship.

Also, GPS is not OK in war machines as the only navigation source. A GPS boots with good precision in no time, but is dependent on a external signal that can be disturbed or spoofed. INS/IRS is not sensotive to this, but need to align properly to be accurate enough for modern warfare.

Edited June 29, 2018 by Gunnars Driver

[russhin]

Laser Ring Gyros don't need the calibration, but I think the system that takes the data from it does, which is the calibration portion I believe