INS Alignment

[Direwolf]

Where (on which page) I can see my INS alignment is done? I remember on A-10C we received an Ok, allowing us to change from Ground to NAV (~7 to 8 minutes after start). I know FA-18C alignment is much more faster than A-10C, but we need a go to change to NAV.

[uunilenkki]

HSI

[ekg]

On the MPCD there is a timer and count down when the ins is in ground mode. It took about 3 minutes for the calibration to complete.

[Direwolf]

Color Map

 

Yep! It is there! Thx in advance, but I have another question: my HSI map is too bright (maybe some bug to be fixed later), and I barely see the symbols and text. Is there any way to turn it black and green, lihe the others DDI´s?

[S D]

There should be a feature to turn the map background off, but it is not simulated yet.

 

 

Your best option is to put the HSI on one of the other non-colour screens.

[Direwolf]

THX! That´s what I´m gonna do!

[DracoLlasa]

Yep! It is there! Thx in advance, but I have another question: my HSI map is too bright (maybe some bug to be fixed later), and I barely see the symbols and text. Is there any way to turn it black and green, lihe the others DDI´s?

 

if you enable the HSI on the right or left DDI it will show without the map, that will let you see the text clearly, as i had the same problem, i cant see/read the text on the center MFPD without zooming way in on it which is not really possible in flight

[Archer_111]

Actually the INS aligment countdown only takes 96 seconds to complete, and then it says " 0.5 OK " on the moving map. The "0.5" stays there and doesn't turn into 0. Does it mean the aligment process is really complete and O.K. to switch the INS knob to NAV ? Why people say it takes 3 to 4 minutes ?

[Luzifer]

It doesn't go further than "0.5 OK" and GND alignment takes 3 minutes and a few seconds for me.

[Archer_111]

It doesn't go further than "0.5 OK" and GND alignment takes 3 minutes and a few seconds for me.

 

Oh, mine was on the CVN -74 Stennis sailing at 25 Knots , even the coordinates drifted constantly, the calibration did work and finished in 96 seconds. So the countdown time really depends on the locations, I think.

[Archer_111]

For carrier ramp starts, do we switch it to NAV from CV after its done aligning?

 

Yes, I did. Just standard .

[DracoLlasa]

the CV and GND are just where the alignment is taking place from

the CV align is notably shorter from what i gather as its taking INS alignment data from the actual carrier, vs doing it all on its own on the GND so the CV alignment will go faster

 

but in either case you start with CV or CNG then go to NAV before you start moving

[Archer_111]

the CV and GND are just where the alignment is taking place from

the CV align is notably shorter from what i gather as its taking INS alignment data from the actual carrier, vs doing it all on its own on the GND so the CV alignment will go faster

 

but in either case you start with CV or CNG then go to NAV before you start moving

 

Thanks for explaining, that makes sense:).

[QuiGon]

the CV and GND are just where the alignment is taking place from

the CV align is notably shorter from what i gather as its taking INS alignment data from the actual carrier, vs doing it all on its own on the GND so the CV alignment will go faster

 

but in either case you start with CV or CNG then go to NAV before you start moving

As far as I understand it should be the other way around, as INS alignment is much more difficult on a moving platform. INS alignment means, that the gyros need to adjust themselves for the earths rotation. This is no problem if the aircraft stands still on the ground and rotates with the earth, but when the aircraft stands on a platform that itself is moving, it needs the motion data from that platform to substract it from the movement that the gyros sense. Carrier alignments should take longer and should be less precise in the end because of this.

That's at least my understanding of INS alignment.

[idenwen]

Actually the INS aligment countdown only takes 96 seconds to complete, and then it says " 0.5 OK " on the moving map.

 

But I have the strange feeling that that is not real time, especially the last 20 secs seem to be slower. But maybe I was only tired...

[Flamin_Squirrel]

As far as I understand it should be the other way around, as INS alignment is much more difficult on a moving platform. INS alignment means, that the gyros need to adjust themselves for the earths rotation. This is no problem if the aircraft stands still on the ground and rotates with the earth, but when the aircraft stands on a platform that itself is moving, it needs the motion data from that platform to substract it from the movement that the gyros sense. Carrier alignments should take longer and should be less precise in the end because of this.

That's at least my understanding of INS alignment.

 

 

 

I've never given this much thought before, but why does a gyro even need to adjust? I have no idea; laser ring gyros don't even have moving parts!

 

 

I believe CV based alignment takes a feed from the ship's INS; perhaps this is why alignment is faster?

 

 

Interesting stuff, be nice if someone knows the answers.

[QuiGon]

I've never given this much thought before, but why does a gyro even need to adjust? I have no idea; laser ring gyros don't even have moving parts!

 

 

I believe CV based alignment takes a feed from the ship's INS; perhaps this is why alignment is faster?

 

 

Interesting stuff, be nice if someone knows the answers.

 

 

The data that is supplied by the ship only tells the aircraft its current position and the ships movement, so the aircrafts INS knows where it is at all times during alignment and can substract the ships movement to get the rare movement based on earth rotation. When starting on the ground on an airfield, you just enter the current position before starting the alignment and you're good, because the airfield itself doesn't move across the ground, so the INS can align itself to the earths rotation just fine.

Here are more detailed explanations: https://forums.eagle.ru/showthread.php?t=205401