Aligning INS's in strange places

[18-Wheeler]

I was pondering this the other day, mucking around with a Flanker SU-27 simulation.
How does the military gear align the INS's when moving along on a carrier? The carrier's not only moving across the ater, but up & down & side-to-side a fair bit as well I'd imagine.

[RadarContact]

"I could tell you - but then I'd have to shoot you." ist probably the most common answer to this one... ;)

Made me curious, though. A brief search in Google (love it) led me here (http://www.ngnavsys.com/Html/LN-94/) and here (http://pma209.navair.navy.mil/index.cfm?PlatformID=4&ProgramID=11).

Unfortunately, no further information other than that they can do it and that it was bloody expensive to get them to do it.

[spanner-do]

Head appears over the parapet

They do it through a simple patch lead which connects the IRU of the aircraft to the Carrier position/location IRU or whatever system they are using currently.

The RAF Harriers had to be modified to enable this to occur when they became part of the Task Force.


Stands by for firing squad to arrive
Ouch

[Intruder]

Best alignments are done with cable or radio data link to the Ship's INS (SINS). Position, course, and speed of the ship are then available. Height above water (flight deck height) is entered. The software in the aircraft INS resolves the "spotting angle" -- the difference between the aircraft heading and the centerline of the ship, and the alignment can complete.

Without the data link from SINS, position, course, and speed have to be estimated and manually input (flight deck personnel may hand the pilot a sheet of paper with the info, or hold up a chalkboard. The pilot can tell if the alignment is proceeding nominally if the spotting angle output settles down at a reasonable value.

[18-Wheeler]

Thanks for that guys, very interesting indeed!