Gulfcapt
Our two jets both came from the OEM with one of the three IRS racks aboard out of alignment. It was no small task to have this corrected by them. IIRC, they referred to the process as "re-racking." Musta just been an in-house term.
ahh now it makes sense (really a worry how these racks got misaligned during installation, normally such a lot of care is rightfully taken over this). I can imagine the difficulty involved in getting it right, I've seen alignment during aircraft manufacure and it needs a lot of care and precision.
Thanks very much for the feedback GC
Rudderrudderrat
How did Concorde's INS keep sense of True North when you were flying with a Westward ground speed which matched Earth's rotation rate? In that case the aircraft would have no apparent rotation around Earth's Axis in space, so no apparent wander. I'm guessing that the flight time was so short, that the INS just had to "remember" where True North lay.
Hi again (in a different thread for a change
). The 'remembering' true north is a case of the Z axis gyro taking up a position in inertial space during alignment, the angle between itself and true north will be a constant; the gyro remainig fixed on this position for the entire time the INS is operating. Sector lengths are not really an issue as far as the 'true north' bit goes, in fact it's quite irrelevant. The only time issue are just the normal time growth errors associated with any inertial system. (The fundamental limit for an INS being 3 + 3T NM; T being the time that the INS was in NAV mode).
Time growth errors were of course helped by our short sector lengths, but we still used aided navigation, where within range of a VOR, the co-sited DME clant range was used to greatly deruce errors. While oceanic we would mix the inertial positions of all 3 INSs to produce a mean computed position.
Dude
