cannot repoduce and missing track file F-16 INS Mis-Alignment

[RedBack]

Hi 

I'm new to DCS so forgive any dumb questions

After doing a cold start with Stored Heading alignment, I fly a mission, and all is OK.

After landing back to base to rearm and refuel, I noticed that the INS is now misaligned.

I tried to do an inflight alignment, but I can't get it to work.

To do inflight alignment,

1. I fly strait and level using the Auto pilot
2. I set the INS to InFlight Alignment
3. I enter my magnetic compass heading into DED
4. I wait until alignment count down to 10 and the "Align" sign on the HUD disapears
5. I click Return on DED
6. I set the INS to NAV

The result of this procedure, gets me close alignment but not exact.  

Can someone tell me

1. what causes the INS to be misaligned? 
2. Do I have to realign the ins after every landing?
3. What am I doing wrong with the in flight alignment?

[razo+r]

1) Every INS slowly drifts over time that makes the whole system inaccurate the more time passes. In modern aircraft, GPS may be used to correct the drift, but in DCS your aircraft may or may not have access to GPS if the date is set pre-GPS or if you fly for the RED faction without the option "unrestricted SATNAV" checked.

2) Normally, no.

Have you tried doing a fix instead of an in flight alignment?

[RedBack]

36 minutes ago, razo+r said:

1) Every INS slowly drifts over time that makes the whole system inaccurate the more time passes. In modern aircraft, GPS may be used to correct the drift, but in DCS your aircraft may or may not have access to GPS if the date is set pre-GPS or if you fly for the RED faction without the option "unrestricted SATNAV" checked.

2) Normally, no.

Have you tried doing a fix instead of an in flight alignment?

Re1 F16 is a moden aircraft (I thought) and does have GPS. Is this the setting that needs to be checked?

What so you mean by "Doing a fix instead of an in flight alignment"?

Edited February 28, 2024 by RedBack

[razo+r]

21 minutes ago, RedBack said:

Re1 F16 is a moden aircraft (I thought) and does have GPS. Is this the setting that needs to be checked?

Unrestricted SATNAV is only needed if you fly for the red coalition or for whatever reason have set a date before GPS was introduced. If you fly for the Blue coalition, this option does not have to be checked (provided the mission date is after the introduction of GPS).

 

21 minutes ago, RedBack said:

What so you mean by "Doing a fix instead of an in flight alignment"?

 

I mean taking an INS fix... You update your INS based on the manual correction of a waypoint from it's drifted INS position to the actual, correct position.

 

Edited February 28, 2024 by razo+r

[RedBack]

Couldn't find how to set the mission date except through the weather setting (see image below).  

If that is the mission date, then 2016 shoudl be after the GPS introduction date. is that correct or is there some other place to set the mission date?

 

The video to fix way point drift is very helpfull. I didn't know you can do that, thanks. I'll give it a try at next mission

Edited February 28, 2024 by RedBack

[AngryViper.101]

From my experience, when doing an inflight alignment, do not change the know to NAV, leave in in the inflight alignment position after aligning is complete.

remember to press ENT and dobber down three times.

let me know if you want clarification

this appears to work for me

after a hard landing and some light damage i usually do a full alignment before taking off
1. remember to not do this while loading the aircraft, any movement will result in failed alignment

2. turn the INS know off for 10 seconds

3. then turn it to the NORM mode
4. remember to in the DED hit enter for long, lat and altitude within the first few seconds 

5. wait for the align to flash in the hud and the ready flash

6. turn the INS knob to NAV

 

It takes a while, but in single player you can fast forward time...

[QuiGon]

21 hours ago, RedBack said:

Can someone tell me

1. what causes the INS to be misaligned? 
2. Do I have to realign the ins after every landing?
3. What am I doing wrong with the in flight alignment?

1) If GPS is available (meaning mission date is after 1994 and you fly in the same coalition as the USA) then the INS gets never misaligned as it is constantly corrected by GPS
2) No
3) IFA is a bit of an emergency procedure to re-align a failed INS mid-flight which is extremely rarely used IRL as it only offers very poor alignment quality. In DCS there is not really any use for this ever.

[darkman222]

1 hour ago, QuiGon said:

3) IFA is a bit of an emergency procedure to re-align a failed INS mid-flight which is extremely rarely used IRL as it only offers very poor alignment quality. In DCS there is not really any use for this ever.

Depends. If you took off after a repair the INS is misaligned.

So what works best: autopilot to altitude hold, and try to fly straight and level as best as possible. Seems to work better in single player and worse in multiplayer. But could also be placebo.

Question: What is the best procedure to keep alignment while being repaired?

 

I tried to plug in ground power

Engine off

Get repaired

Start up again.

 

But the INS is misaligned. Now either a full alignment on the ground is necessary, which takes ages, compared to stored align. Or as described above the inflight alignment is the other option.

[QuiGon]

Just now, darkman222 said:

Depends. If you took off after a repair the INS is misaligned.

Yes, but then the normal thing to do would be a ground alignment, just like you do when you start your flight at the beginning of the mission. This way you get a precise alignment, which is not possible with an IFA alignment.

[darkman222]

Yeah. So I was wondering if there was a quicker way.

As far as I know, its not possible to store the alignment before engine shut down. So using stored align is no option after repair.

 

I was hoping that keeping the jet on ground power would keep the alignment valid through out the repair. Does not seem so.

[MAXsenna]

Yeah. So I was wondering if there was a quicker way.
As far as I know, its not possible to store the alignment before engine shut down. So using stored align is no option after repair.
 
I was hoping that keeping the jet on ground power would keep the alignment valid through out the repair. Does not seem so.

One can't store? I'm positive I saw a video where it was done, so I just assumed it worked. Never tried though.

Sent from my SM-A536B using Tapatalk

[RedBack]

Thanks for the comments all.....

OK So my mission date is 2016, I have GPS switch ON, I fly for US Airforce, and yes, my landing at times can be rough as I try to flare. So based on the above, GPS should maintain constant alignment. But that is not the case.

After landing and re-arming If I take off, my way point positions are way out of alignement and not where they are suppose to be per mission plan. My hud is misaligned.

I found that after landing and re arming, a full alignment fixes this (no point in resuming the mission only to find out I'm misaligned after takeoff).

13 hours ago, AngryViper.101 said:

after a hard landing and some light damage i usually do a full alignment before taking off
1. remember to not do this while loading the aircraft, any movement will result in failed alignment

2. turn the INS know off for 10 seconds

3. then turn it to the NORM mode
4. remember to in the DED hit enter for long, lat and altitude within the first few seconds 

5. wait for the align to flash in the hud and the ready flash

6. turn the INS knob to NAV

 

Sad thing is it take 8 LOOOONG min but it works.

Is there any other way to speed this up (say with stored heading)?

[darkman222]

Maybe you can just make a track file or a video of it?

I can see no issue you should run into with what youre doing.

As far as I know you cant just store your heading and restore it. The stored heading seems to be only for the place you started the mission in or where you spawned in.

While youre preparing your track file

Does anyone know if it is really not possible to store the alignment before engine shut down?

And how can I keep the alignment during repair? Or is it just not possible?

Edited February 29, 2024 by darkman222

[QuiGon]

14 hours ago, RedBack said:

OK So my mission date is 2016, I have GPS switch ON, I fly for US Airforce, and yes, my landing at times can be rough as I try to flare. So based on the above, GPS should maintain constant alignment. But that is not the case.

After landing and re-arming If I take off, my way point positions are way out of alignement and not where they are suppose to be per mission plan. My hud is misaligned.

That's quiet odd. There's no reason why this would happen. Can you share a track replay of such a flight where this happens (the shorter the better)?

  

14 hours ago, RedBack said:

I found that after landing and re arming, a full alignment fixes this (no point in resuming the mission only to find out I'm misaligned after takeoff).

If you have moved away from your initial spawn position you have to update the coordinates on your INS page on the DED within the first two minutes of alignment.

  

14 hours ago, RedBack said:

Sad thing is it take 8 LOOOONG min but it works.

Is there any other way to speed this up (say with stored heading)?

Stored heading is only available as long as your aircraft hasn't moved since you spawned in. The only other way to speed this up is by accellerating the simulation time with Ctrl + Z, but that only works in singleplayer of course.

Edited March 1, 2024 by QuiGon

[RedBack]

12 hours ago, QuiGon said:

That's quiet odd. There's no reason why this would happen. Can you share a track replay of such a flight where this happens (the shorter the better)?

I'm not sure that I DCS stores track files for previous misssions. I'll try and produce a track file when I next play the mission

 

12 hours ago, QuiGon said:

If you have moved away from your initial spawn position you have to update the coordinates on your INS page on the DED within the first two minutes of alignment.

Good to know. To make sure that I have the correct INS coordinates, I alsway return to the initial spawn location

 

12 hours ago, QuiGon said:

The only other way to speed this up is by accellerating the simulation time with Ctrl + Z, but that only works in singleplayer of course.

Good suggestion thanks

[darkman222]

24 minutes ago, RedBack said:

I'm not sure that I DCS stores track files for previous misssions. I'll try and produce a track file when I next play the mission

DCS does for Multiplayer missions. Not for single player. You gotta reproduce it. Otherwise I'd say be cautious what you do after touchdown. Dont flip switches accidentally. That includes the ones that you might or might not have bound to your hotas, keyboard etc intentionally, or that DCS comes with it bound by default.

Edited March 2, 2024 by darkman222

[Machalot]

Are you possibly switching to ground power and shutting down the engine while you rearm?  For some reason the Viper in DCS can't transition between external and internal power without messing up the INS.  In general you don't need to switch to ground power when rearming, and the INS should maintain its state if you just keep it in NAV.

Edited March 5, 2024 by Machalot

[RedBack]

10 hours ago, Machalot said:

Are you possibly switching to ground power and shutting down the engine while you rearm?  For some reason the Viper in DCS can't transition between external and internal power without messing up the INS.  In general you don't need to switch to ground power when rearming, and the INS should maintain its state if you just keep it in NAV.

 

No I don't power down the Jet or switch to ground power while rearming.

[Machalot]

2 minutes ago, RedBack said:

No I don't power down the Jet or switch to ground power while rearming.

And you're leaving the INS in NAV mode?

[RedBack]

On 3/5/2024 at 12:41 PM, Machalot said:

And you're leaving the INS in NAV mode?

Yes

[darkman222]

Dude. Without a video or track file, nobody will be able to help you. This just sounds like a double bound hotas button, switching something off while landing, that messes up your alignment.

[RedBack]

21 minutes ago, darkman222 said:

Dude. Without a video or track file, nobody will be able to help you. This just sounds like a double bound hotas button, switching something off while landing, that messes up your alignment.

I'm trying to replicate the issue. Flew the same mission 3 times and cannot replicate the misalignment. I'm going to put it down to possibly hard landing that causes the misalignment!