Salute!
At all above! PLZ read up a bit about how inertial systems work and what is needed to "align" them. Several misconceptions and misunderstandings repeated here and incomplete knowledge of how the damned systems work.
First, a few clues to guide you....
- The "system" may be composed of several sensors, not just one magic box.
- The system may not be meant to provide extremely accurate body rates and such for display ( e.g. inertial vertical velocity versus barometric perssure changes) , but basic navigation coordinates with a specified accuracy and update timeframe. You know, where am I?
- an inertial system does not need to be mechanically postioned in "inertial" space to work like they did in the really old days. See "strapdown" systems and RLG's. The tiny one in an AMRAAM is ready to go within a second, and does real well.
- Since the 60's, at least one USAF attack plane could do airborne alignments for navigation and then bombing calculations. A rough initial position was good enuf, then takeoff after 2 minutes or less. The navigation computer then used Doppler info and crude body rates from the inertial platform, which was only good for AHRS at that stage. Kinda like 99% of everything flying. Using doppler and great software, the system could be "aligned" to a "reasonable" state. A radar or visual or flyover position update refined the whole deal and then the thing got better as it then knew lat long, which provided earth rotation rates and better calculation of the wander angle, local level, etc. etc.. I leave it to the reader to research that system and plane.
Gums sends...