by thebrelon » Sat Jul 29, 2006 3:47 am
IRS don't have to be calibrated but aligned...
they are gyros systems, and as such before being the accurate navigation system they are the gyros have to speed up to a certain speed ,where they become "rigid". which mean that there spining axis is always in the same position in respect of stars, ie whatever movement did the plane do, and even the earth, the spin axis is always pointing to the same direction.
when the A/C move calculations take place and process the actual A/C position + many other parameters. it just needs to be fed with the actual A/C position while aligning.
for that reason A/C must not be moved during the alignement process.
INS are based on the same principle but use accelerometers fixed to the frame of the aeroplane. every single movement is caused by an acceleration in different axis. this acceleration is measured and integrated one time to get a speed, and a second time to get a distance. again they need to be aligned, and you need to tell the "thing" what's its actual position during alignment. then you have an initial position, an acceleration, a speed and a distance, which is far enough to compute the actual position.
add to this few Air Data Computer which will process, from static pressure and pitot pressure, many parameters like speed, altitude, vertical speed...
feed all the informations computed by the IRS/INS, ADC to the FMC and then you have an extremely accurate and powerfull tool to navigate.
to understand and use these systems need A LOT of reading and training, and one may not feel the need to use them when others may will to master them. both are respectable.
myself I prefer flying manually ...
If PMDG can do it, MS should be able to do it too... then it would probably be a great added value to FSX. for virtual airline, for example....
my two cents.....
vince
laptop: kenitec D900TV
Pentium 4 3.4gHz HT
4Gb corsair DDR II 533MHZ
2x 60Gb Hard drive
Nvidia geforce 6800 DDR3 256 Mb