How long is the INU alignment supposed to take?

[CrazyGman]

I was wondering how long the INU alignment is suppose to take?.It seems to take longer for me in a mission editor start up mission. Then in videos on YouTube. I assume like a INS I want it to complete before I take off

[admiki]

It should be 4 minutes after APU start

[Frederf]

What is the indication that alignment is satisfactory or complete? I've just been using when the TSD chart layer is visible but that seems unscientific.

[frostycab]

12 minutes ago, Frederf said:

What is the indication that alignment is satisfactory or complete? I've just been using when the TSD chart layer is visible but that seems unscientific.

On the TSD, go to UTIL at T6. You will see the 2 INUs in the top box. They start out white, but turn green when confidence is high enough.

[Zyll]

The charts on the TSD also appear once the alignment is complete, 4:20 to be exact.

[frostycab]

9 minutes ago, Zyll said:

The charts on the TSD also appear once the alignment is complete, 4:20 to be exact.

Interesting. What map was that on? I timed it on the Caucuses map and got 3:55 from APU ON light. I wonder if they've modelled the Earth's rotation into the alignment, as I understand that it can take longer depending on your latitude in some civilian aircraft.

[Zyll]

That's interesting. I didn't do Caucasus, I was on Syria and maybe Marianas. Not they I think of it, my timing might be from the moment I start the battery in my startup procedure. What I had noticed, is that turning on the Doppler has no effect on the speed to alignment.

[frostycab]

12 minutes ago, Zyll said:

 What I had noticed, is that turning on the Doppler has no effect on the speed to alignment.

It shouldn't. Doppler systems rely on changes in frequency in the signals they emit relative to what they send out. If the aircraft is stationary then there would be no doppler shift. I was told that it's used to aid in making corrections for INU drift over time/distance. (That's my recollection anyway, but I'm getting sleepy now. LOL)

[PlainSight]

From the manual:

"The EGI alignment process uses the aircraft’s previous position and heading stored in the aircraft memory from when it was last shut down. This stored position, aided by GPS position signals, shortens the alignment process considerably, allowing an AH-64D to takeoff within minutes if necessary."

Looks like ME does not input the last postion into the helicopter when you load it up, so you need to wait for the complete alignment.

F-16 has this stored alignment option and that takes one minute to complete.

[Swift.]

9 hours ago, frostycab said:

Interesting. What map was that on? I timed it on the Caucuses map and got 3:55 from APU ON light. I wonder if they've modelled the Earth's rotation into the alignment, as I understand that it can take longer depending on your latitude in some civilian aircraft.

It's also possible it's random. It looks like they e already modelled the INUs drifting and having them drift independently from each other. Also looks like the GPS satellites it detects aren't always the same. 

[Nevyn]

I was sitting at Jean airfield in Nevada the other day at around midday, fairly warm, and it took about seven minutes (That's a rough guess, I didn't actually time it but it took a lot longer than I am used too.)

[QuiGon]

The DCS Apache still misses an alignment process for when GPS is not available. The INU confidence never turns green in such scenarios

[poochies]

8 minutes ago, QuiGon said:

The DCS Apache still misses an alignment process for when GPS is not available. The INU confidence never turns green in such scenarios

Would the required number of satellites not being  available cause no  GPS ? How else  would it not be available ? System failure maybe ? We've flown through hot zone  areas in real life where gps is jammed .... 

[QuiGon]

8 minutes ago, poochies said:

Would the required number of satellites not being  available cause no  GPS ? How else  would it not be available ? System failure maybe ? We've flown through hot zone  areas in real life where gps is jammed .... 

In DCS GPS is not available if you fly on RED side (without the USA being on RED side I think) or if the mission date is before 1994. You will see that the satelite info on the Apaches TSD-UTIL page will show zeros. It's great to simulate older missions (Dessert Storm, Cold War) or missions in GPS degraded/denied environments (the enemy has jammed or even shot down GPS satelites).

Unfortunately pure INS alignment (instead of EGI alignment) is not yet implemented apparently, although I have to admit that I have no clou how it would look like. I would expect though that you must enter your startup coordinates manually somehow.
The INS UPDATE function of the STORE/UPDATE switch is also not implemented yet it seems.

Edited April 3, 2022 by QuiGon

[AstonMartinDBS]

20 hours ago, frostycab said:

They start out white, but turn green when confidence is high enough.

Good to know! I didn't recognice this until I'd read your comment.

Alignment incomplete:

Alignment complete:

 

Edited April 3, 2022 by AstonMartinDBS

[csdigitaldesign]

INU does not need to be grounded to align since the Apache has GPS. You can take off and let it align in flight. I do it all the time.

[QuiGon]

1 hour ago, csdigitaldesign said:

INU does not need to be grounded to align since the Apache has GPS. You can take off and let it align in flight. I do it all the time.

While this works in DCS, I'm not sure if this is correct, because the purpose of the alignment is not to get a position, but to adjust the INU to the rotation of the earth and such.

Edited April 4, 2022 by QuiGon

[84-Simba]

Is there a way to recalibrate INS ?

After an around 30min flight my INS seems to be off.

When I enter JTAC coordinates and slave on that point it is waaay off the intended target ...

Add to that that I cannot shack anything with the Limas ... they end up where the INS falsely place the point and never track.

Weird.

[Hobel]

vor 58 Minuten schrieb 84-Simba:

Is there a way to recalibrate INS ?

After an around 30min flight my INS seems to be off.

When I enter JTAC coordinates and slave on that point it is waaay off the intended target ...

Add to that that I cannot shack anything with the Limas ... they end up where the INS falsely place the point and never track.

Weird.

as far as I know this is also known in connection with the Hellfire Lima

[84-Simba]

What do you mean ?

[NeedzWD40]

3 hours ago, 84-Simba said:

Is there a way to recalibrate INS ?

The only way is to do an INU reset on both units. Land and go to the TSD UTIL menu and the options should be available there. Note that if you're doing this in multiplayer, there is a permanent offset from INU position to real position; I am uncertain the reasoning for this. Rough rule of thumb is ~150m off latitude and ~350m off longitude. The direction varies from map and time of year, ie summer Syria offsets are north and west.

The ability to manually enter position coordinates is not implemented yet.

[NeedzWD40]

Correction to my previous post: there is an offset in single player as well. One picture from multiplayer, one from single player.

[Ignition]

The INS is still not fully simulated?

 

[QuiGon]

On 9/4/2024 at 7:06 AM, Ignition said:

The INS is still not fully simulated?

Yes

[bradmick]

When I read “I don’t wait for the INU to align before taking off” I immediately stop taking anything that individual has to say with regards to “bugs” or “issues” seriously…especially when it has to do with weapon or sensor accuracy. The system is meant to have that alignment complete. Not allowing it to complete prior to takeoff is something a real operator of the aircraft would never do. So if you’re not willing to wait and let the system properly “boot up” so to speak, I’m not willing to consider any issues with accuracy as being aircraft related and instead see them as user related. But that’s just me.

Edited September 5, 2024 by bradmick