Carrier Spawn Wrong Heading

[pierrewind]

Hello Heatblur,

I have noticed an issue when spawning on the carrier in multiplayer, the heading can be offset by about20 degrees. (HDG324 instead of 342 observed).

I have attached a track.

Ps: Stby compass and Slaved appear as wrong, COMP seems ok. Though I am not sure how deep are these systems modelled! 

 

Aerobatics Europe Caucasus-20210511-141519.trk

Edited May 11, 2021 by pierrewind

[near_blind]

The carrier is a giant ferro-magnetic object, and will disrupt compasses when you are near it. 

[pierrewind]

Thanks for the answer @near_blind,

There are surely some errors induced from the carrier, actually even avionics can disturb the compass.

But in the worst case scenario, once flying in slave mode, the compass should regain the correct heading. It will actually do the opposite hooking onto the wrong heading.

That is making for extremely confusing tacan use for example (as if you were flying in 100kts+ crosswinds), and this is wrong.

[pierrewind]

Up


Still showing this problem... ( here lined up on the cat with correct BRC set; carrier spawn )

[IronMike]

That is intended. Pressing the COMP button on the AHRS panel will get it back on the correct heading after take off again (once airborne and with a bit of distance from the carrier). The deviation can be as large as 30+ degrees.

[Slant]

19 hours ago, IronMike said:

That is intended. Pressing the COMP button on the AHRS panel will get it back on the correct heading after take off again (once airborne and with a bit of distance from the carrier). The deviation can be as large as 30+ degrees.

 

Do you happen to have some guidance on how they managed to depart parallel/on BRC in CASE 1/3? Specifically, did they fly ground track or heading? When did they press that comp button? Also, what did they do during CASE 3 specifically, cos they're basically never straight and level with zero acceleration until they're on the outbound radial. Being up to 30° off on that outbound radial seems incredibly unsafe. Not to mention thatt hey're about to do a CV rendevouz and wingman potentially being 60° off on that radial...

 

We're struggling making heads or tail off of NATOPS procedures with basically an unreliable (aka useless) INS directly after launch. CASE 1 ain't too bad, I can manage to get it synced up within the 7 miles on a good day, but CASE 3, no idea...

Edited September 25, 2021 by Slant

[sLYFa]

Tacan radial/bearing indication is independent from any heading reference, so you should be able to fly correct radials regardless of any magvar induced errors. In DCS however, your AHRS heading will wrongly influence Tacan data, I hope HB will fix this someday. In the meantime, put the AHRS in DG mode and manually adjust your heading to a known value (on the boat it will be ships heading plus or minus 90, depending on which side of the boat you are parked). 

[pierrewind]

 

HDG Difference (COMP/SLAVED) on carrier deck... Does not match

 

Edited September 26, 2021 by pierrewind

[pierrewind]

On 9/24/2021 at 10:12 PM, IronMike said:

That is intended. Pressing the COMP button on the AHRS panel will get it back on the correct heading after take off again (once airborne and with a bit of distance from the carrier). The deviation can be as large as 30+ degrees.

Hi @IronMike

Did some additional testing.

I think there are still a few issues. 

COMP mode shows correct heading. Though in COMP Mode, HUD and VDI are showing hdg 360... 

SLAVED mode. Will not slave correctly by itsef (30mn +)  or by pressing HDG KNOB (1mn +) ! Seem to slave correctly after  USING DG (was still about 5 degrees off).
As noted in the manual, pressing the HDG KNOB should help it sync. But It didn't actually make any difference

Additionaly SYNC doesn not seem to be applied correctly. (LEFT/RIGHT sync shows sync left or right based on heading... It should actually ALLWAYS show the correction to make ( Heading 360, actually on 350, 350-360 = -10, slave to the left...) Doesn't behave like this at the moment)

DG mode. Nice to help sync SLAVED But HDG KNOB is very finiky to adjust. 

After a landing on the carrier, SLAVED (slaved to false heading) and COMP do not show the same heading. (maybe ok? before the first T/O)

It may be worth it to have a look at this compass thing again...

Edited September 26, 2021 by pierrewind

[IronMike]

Marking @Super Grover so he can take a look.

[Super Grover]

Noted. I'll take a look at the code and get back to you.

[Super Grover]

I've checked the code against the documentation, and when in SLAVED, pressing the HDG KNOB slaves the synchro. However, synchronization cannot be accomplished if the F-14 is accelerating or decelerating by more than 75 knots per minute. This implies very stable flight conditions, so probably you were limited by that acceleration gate.

I've also checked the +/- deflection of the needle, and indeed it looks to be wrong. I reversed it, and the needle should be fixed in the next update.

Thank you for your feedback.

Best regards

grvr

[Slant]

4 hours ago, Super Grover said:

I've checked the code against the documentation, and when in SLAVED, pressing the HDG KNOB slaves the synchro. However, synchronization cannot be accomplished if the F-14 is accelerating or decelerating by more than 75 knots per minute. This implies very stable flight conditions, so probably you were limited by that acceleration gate.

I've also checked the +/- deflection of the needle, and indeed it looks to be wrong. I reversed it, and the needle should be fixed in the next update.

Thank you for your feedback.

Best regards

grvr

 

Thank you for detailing the acceleration gate, I was not aware of the exact number. So basically, 1.25 knots per second acceleration/deceleration will prevent synchronisation from happening. That's not a whole lot and confirms my experience.

 

I guess this is one of the things that were easier when flying in the jet irl.

[pierrewind]

On 10/8/2021 at 4:10 PM, Super Grover said:

I've checked the code against the documentation, and when in SLAVED, pressing the HDG KNOB slaves the synchro. However, synchronization cannot be accomplished if the F-14 is accelerating or decelerating by more than 75 knots per minute. This implies very stable flight conditions, so probably you were limited by that acceleration gate.

I've also checked the +/- deflection of the needle, and indeed it looks to be wrong. I reversed it, and the needle should be fixed in the next update.

Thank you for your feedback.

Best regards

grvr

 

Thank you Super Grover for the infos.
Indeed SLAVED SYNC  works at very low accelerations ! Is it only based on gx acceleration ? is there also pitch/bank limits ?

I guess the HUD and VDI showing hdg 360 in compass mode is normal behaviour then? 

And what about COMP and SLAVED showing different headings on the deck? 

 

Thanks again ! I look forward to the next gorgeous  update  

 

Best regards

Edited October 10, 2021 by pierrewind

[Super Grover]

These are very interesting questions .

 

On 10/10/2021 at 2:30 AM, pierrewind said:

Indeed SLAVED SYNC  works at very low accelerations ! Is it only based on gx acceleration ? is there also pitch/bank limits ?

The displacement gyroscope of the AHRS device A/A24G-39 has two acceleration sensors: fore/aft and turn. However, on the F-14, the turn sensor is not used. This looks like a serious design flaw, but in my sim tests where I flew with the debug displays, I noticed that the fore/aft sensor gate prevents the torquers from applying the corrections to the gyroscopes and the synchro even in turns (thank you, physics). Ofc very shallow turns or small pitch changes can result in introducing errors to the system.

 

On 10/10/2021 at 2:30 AM, pierrewind said:

I guess the HUD and VDI showing hdg 360 in compass mode is normal behaviour then?

This isn't normal behaviour in a normal situation with all devices working correctly. However, recently, I discovered that a part of the HUD/VDI heading tape code got accidentally replaced with a very old code. So I corrected that, and the fix should be in the upcoming update.

 

On 10/10/2021 at 2:30 AM, pierrewind said:

And what about COMP and SLAVED showing different headings on the deck? 

If you mean after landing, then it's a feature and not a bug, and simply the magnetic field from the carrier disturb the readings in COMP, while the gyros/synchro need some time to adjust.

[pierrewind]

Thank you for these great insights Super Grover ! 

This AHRS device sure sounds like a bit of a sensitive relic !  I must say I am amazed at the very enjoyable level of details that was brought into this module ! 
 

3 hours ago, Super Grover said:

If you mean after landing, then it's a feature and not a bug, and simply the magnetic field from the carrier disturb the readings in COMP, while the gyros/synchro need some time to adjust.

As for this point, the above behaviour does make perfect sense. However, it is not what seems to happen.
After startup I have both my COMP and SYNC on the same heading as expected. 

But, then as I come back to the deck, I frequently have SYNC going as expected to the false heading, while COMP remains on the good heading. At times, I have observed this error before even launching off the deck.

I have attached the track it should show this quite clearly. You may have to time accelerate to skip the first few mins. Error is shown lined up on the cat.
https://mega.nz/file/ADxHHApB#KSgNPGgkCiYRv6E4wmL9VNa3tcbwFkrJCw7iNT37ybQ

Edited October 11, 2021 by pierrewind