reported INS drifts way too much

[SnuggleFairy]

In the track and video below I do a cold start and precise alignment with external power as per manual. After take off my heading is correct, my current coordinates are correct and the autopilot is taking me towards the waypoint 2 correctly. But within 2 minutes of flight it starts making a left turn with the designated heading reticle going left and the more you fly the more it gets confused where the aircraft is. If you switch to the current coordinates on the PVI, the values will be nothing like the values on the ABRIS - it thinks it's somewhere else. That deviation affects the datalink and the "turn on target" mode. I demonstrate how those modes behave in the video and the replay. After I create a reference point under myself by pulling coordinates from ABRIS and correct the deviation. The turn on target and datalink start working properly. More or less anyway. Datalink is not precise because in the time it takes me to save and "ingress" onto target (30 seconds max) the INS already accumulates an error and coordinates in ABRIS and PVI don't match again.

I have no idea what the issue is exactly - cold start or precise alignment is buggy or what, but it drifts way too much, we can't correct it every kilometer of flight.

Track:

https://drive.google.com/file/d/1p7IF2RYokj7znBP12lhJfkF3AlUT9ul9/view?usp=sharing

Video (HD still processing):

 

[bingbean]

Did you use magnetic or gyroscopic heading? They did something with magnetic heading in 2.8 and is somehow inconsistent now. I am not sure if it is the point of your issue es well, but try to use gyro mode. No statement from ED for now about this.

 

[SnuggleFairy]

48 minutes ago, bingbean said:

Did you use magnetic or gyroscopic heading? They did something with magnetic heading in 2.8 and is somehow inconsistent now. I am not sure if it is the point of your issue es well, but try to use gyro mode. No statement from ED for now about this.

 

No, sorry, this is not the issue i'm having

[bingbean]

I know this isn't exactly your problem, I was just wondering if it might be related to this.

So just for curiosity did you try gyro mode?

[jubuttib]

Lots of discussion about this elsewhere too. Precise alignment gets out of whack real fast, while I've had near perfect results with just the bog standard accelerated alignment.

Precise alignment after ~1 hour of flying with autopilot route mode, desired track mode.

Accelerated alignment (with manual heading correction after INU alignment) after doing the same.

Edited December 20, 2022 by jubuttib

[Chizh]

Thank you all for your reports

We found some INS issues in cold start alignment and autoturn to target. Fix will be in January.

Until this fix, I recommend using hot start if you need INS. If not, you have the ABRIS with satellite navigation that does not have deviation.

[xfirf]

Thanks for the info.

[Hobel]

vor einer Stunde schrieb Chizh:

Thank you all for your reports

We found some INS issues in cold start alignment and autoturn to target. Fix will be in January.

Until this fix, I recommend using hot start if you need INS. If not, you have the ABRIS with satellite navigation that does not have deviation.

Is it possible that something is also wrong with the datalink/target points?  Actually, even with an INS that has a drift, after saving and immediately recalling it, you should return to the same position.

But here, too, there is an additional drift that I can't explain.

 

That is good too

 

 

Thx!

Edited December 21, 2022 by Hobel

[Chops]

 

On 12/21/2022 at 9:40 AM, Chizh said:

Thank you all for your reports

We found some INS issues in cold start alignment and autoturn to target. Fix will be in January.

Until this fix, I recommend using hot start if you need INS. If not, you have the ABRIS with satellite navigation that does not have deviation.

I have noticed the same issue with the aircraft wandering all over the place while using Route Mode in the training mission "Enroute Navigation Training".  This mission is a hot start on the runway.  My track file was to large to upload.

[Longiron]

Not to beat a dead horse, but I've believe the issue is tied directly to the Magnetic Variance adjustment.

I've done 3 flights all 1hr+ with little drift now, the startup is bog standard but you will need to switch gyro compass to Magnetic then make the adjustment to align for MV.

Whatever MV you spawn with is not correct, it is for the map but its bugged.

You have to compare the gyro comp and the mag comp then adjust, this must be done before the alignment completes.

From what I see it is about half of what it should be, when showing MV to be 7.4 you need to dial for 15 MV then when alignment is complete check gyro comp and mag comp, fine tune, then switch to GyroComp mode.

I have done this successfully with "quick" and 2x with Norm alignments.

note this still results with the AC POS CAL DATA warning light on the second you go weight off wheels.

Edited December 31, 2022 by Longiron

[JetJake76]

I have even stranger problem with INU, here is what I did:

1. In the Mission Editor I placed a single Ka-50 III on the apron of the Queshm Island airbase (Persian Gulf Map), with option "takeoff from ramp"

2. During the startup, I set the "Normal alignment"

3. After the alignment and startup was over, I manually added a waypoint about 25 km north-east of the airbase, with both PVI-800 and Abris.

4. Before takeoff, the HSI indicated accurate bearing and range to the wayopint.

5. Two cases: if I started engines DURING ALIGNMENT, then after the takeoff, the waypoint began to drift rapidly until the range on HSI was almost 1000 km.

If I started the engines AFTER ALIGNMENT, then after the takeoff, the waypoint began to drift rapidly again, until the range on HSI was about 80 km.

I don't know if it's related to this topic, maybe on the Caucasus map, errors and drifts are smaller.

[Hobel]

vor 2 Stunden schrieb SnuggleFairy:

Looks like INS and auto turn have been fixed

What start-up procedure did you use?

[SnuggleFairy]

28 minutes ago, Hobel said:

What start-up procedure did you use?

The one in the manual with 3 different options for alignment. Precise alignment drifted 0.1 of a minute of a degree after 1 hour and 45 minute flight (aka no noticeable drift). Normal alignment drifted 0.3 of a minute of a degree after the same flight (no noticeable drift), and quick alignment drifted every time you pitch or roll more than 10 degrees (noticeable drift but you can still work with that)

[Hobel]

vor einer Stunde schrieb SnuggleFairy:

quick alignment drifted every time you pitch or roll more than 10 degrees

hm why does an quick alignment  already drift at 10 degrees?

in a test flight i had 1km drifts shortly after take off

[SnuggleFairy]

2 minutes ago, Hobel said:

hm why does an quick alignment  already drift at 10 degrees?

in a test flight i had 1km drifts shortly after take off

Maybe that's how it's supposed to be? I don't know how real KA works. But in DCS if you roll or pitch more than 10 degrees it'll give a "AC-POS. CAL. DATA" warning light on the top lights panel (aka "Aircraft position is roughly calculated using air data systems information") and that results in a drift. After you level out, the light extinguishes and it continues without drift, but with already accumulated error from the maneuver. I'm guessing with quick alignment the accuracy is reliant on the DISS system, and the pitch and/or roll of more than 10 degrees prevents DISS from interpreting the received data correctly.

[Hobel]

vor 7 Stunden schrieb SnuggleFairy:

Maybe that's how it's supposed to be? I don't know how real KA works. But in DCS if you roll or pitch more than 10 degrees it'll give a "AC-POS. CAL. DATA" warning light on the top lights panel (aka "Aircraft position is roughly calculated using air data systems information") and that results in a drift. After you level out, the light extinguishes and it continues without drift, but with already accumulated error from the maneuver. I'm guessing with quick alignment the accuracy is reliant on the DISS system, and the pitch and/or roll of more than 10 degrees prevents DISS from interpreting the received data correctly.

 

 

After the quick start I can fly there directly? 

I heard that the DISS must still warm up, otherwise you get faster drifts.   Does the diss already warm up when you are on the ground or do you need to take off? 

Is there a display that tells me when the diss is warmed up?  

And if it is not warmed up and I take off and then do a fixa later would that be enough?

 

Thx

Edited January 26, 2023 by Hobel

[SnuggleFairy]

1 hour ago, Hobel said:

I heard that the DISS must still warm up, otherwise you get faster drifts.   Does the diss already warm up when you are on the ground or do you need to take off?

 

From my understanding, the DISS is part of the K-041 Rubicon system and it gets turned on by that K-041 switch near your engine startup panel. It takes about 150 seconds to initialize and when you see your HUD appear, DISS should be ready as well. I don't believe it needs to be warmed up beyond that, the manual says it's ready for use after 150 seconds.

1 hour ago, Hobel said:

s there a display that tells me when the diss is warmed up?

After you flick that K-041 switch a yellow warning light "РАНЕТ" / "HUD NOT READY" will come up on the warning panel above your head. That one just warns about the HUD, but it's the similar timer as the DISS. I'll extinguish once the HUD is ready and DISS should be ready as well at that point. From there, if something is wrong with DISS, EKRAN will tell you that.

Edited January 26, 2023 by SnuggleFairy

[Akiazusa]

I think you can check whether DISS is ready by the Ground Speed readout on the HUD

If the GS is displayed on the HUD,the DISS is ready

If the GS line is blank(I mean real blank,not read out is 0),the DISS is not ready

[Hobel]

vor 6 Stunden schrieb Akiazusa:

I think you can check whether DISS is ready by the Ground Speed readout on the HUD

If the GS is displayed on the HUD,the DISS is ready

If the GS line is blank(I mean real blank,not read out is 0),the DISS is not ready

Very good advice, thank you!
so the DISS seems to warm up first or at least only comes on after a while when you have taken off.
as far as I could observe.

[Schlomo1933]

Am 26.1.2023 um 01:12 schrieb SnuggleFairy:

The one in the manual with 3 different options for alignment. Precise alignment drifted 0.1 of a minute of a degree after 1 hour and 45 minute flight (aka no noticeable drift). Normal alignment drifted 0.3 of a minute of a degree after the same flight (no noticeable drift), and quick alignment drifted every time you pitch or roll more than 10 degrees (noticeable drift but you can still work with that)

@SnuggleFairyWith which mission did you test this ? Did you use a quick start mission for this ? The reason i´m asking is , the quick and singleplayer mission are setup to "no alligment and fixtaking needed" in the Mission Editor

I was testing with a selfmade mission and set them up as : "fully realistic" and im not shure if the INU is fixed. It still drifts realy much. 

[SnuggleFairy]

5 hours ago, Schlomo1933 said:

@SnuggleFairyWith which mission did you test this ? Did you use a quick start mission for this ? The reason i´m asking is , the quick and singleplayer mission are setup to "no alligment and fixtaking needed" in the Mission Editor

I was testing with a selfmade mission and set them up as : "fully realistic" and im not shure if the INU is fixed. It still drifts realy much. 

I made my own mission as well. I noticed my old mission had the same setting on "no alignment". I set it up with fully realistic as well. Are you on open beta? Can you attach a track here?

[Schlomo1933]

I’m tomorrow again on the road…. Maybe next weekend I can provide a track.