wip Magnetic compass incorrect declination

[Nealius]

Batumi, 2016, magnetic declination should be -6°. 

 

Control Test

A-10C. Infobar heading (true) 306° compass and HUD reading 300° as expected.

 

Bf109 Test (1200rpm to ensure suction and electric power)

Infobar heading 305°, expected compass reading 299°. Actual compass reading 278° which is 21° more than the correct declination.

Compass-Bf109.trk

Edited September 25, 2021 by Nealius

[fapador]

Seems messed up. I always had a hunch that the compass behaved weird but wasn't totally sure  Needs further investigation as I am not fully familiar with the Axis compasses of the era.

Edited September 26, 2021 by fapador

[amazingme]

I think you should fly perfectly horizontal for the compass to work correctly..

[Ramsay]

4 hours ago, amazingme said:

I think you should fly perfectly horizontal for the compass to work correctly..

 

Correct, I'm not sure what is being modelled but

 

• flying West --> East (95°T), pitching up will cause the compass reading to increase i.e. 90°M --> 120°M

• flying East --> West (275°T), pitching up will cause the compass reading to decrease i.e. 270°M --> 240°M

 

Pitching down has the opposite effect but it's magnitude seems more dependent on how aggressive the manoeuvre was.

 

Flying North or South (005°T/185°T), the effect seemed reduced provided the heading was already close to magnetic North/South

 

Tested at Senaki 2016, using Fw 190 D-9, A-10C measures MagVar = +6.6°E, DCS Open Beta 2.7.6.13133

[Ramsay]

This video suggests the daughter compass should read correctly when stationary and lined up for take off.

 

Note

• @0:17 the compass initially indicates the aircraft/runway heading

 

• @0:47 As the aircraft accelerates to take off, the compass deviates (10-30°) due to the acceleration,

 

• @1:05 Once airborne and flying level the compass pointer returns to it's previous heading until the pilot makes his turn.

 

See my other post on how the RL Master Compass is gimbaled and how the DCS compass should likely read correct when the aircraft is stationary but I'm not a SME.

 

 

[Nealius]

I'm still thinking something is wrong across the board with the Warbirds. My bug report on the Mustang forums has been marked as [Reported], and I'm seeing similar issues with the Spitfire and Mossie main compasses as well. Aligning the gyrocompass with the main compass in both of those aircraft puts me 20deg or more off course even when I account for declination, and I can't navigate well in the Big Show campaign because of it. 

[Ramsay]

On 10/4/2021 at 7:52 AM, Nealius said:

I'm seeing similar issues with the Spitfire and Mossie main compasses as well. Aligning the gyrocompass with the main compass in both of those aircraft puts me 20deg or more off course even when I account for declination

 

I haven't seen the issue with the base magnetic compass (Spitfire is hard to read) but the Mosquito and Spitfire Gyro Compasses are set "wrong" when spawning.

 

Here the Mossie's magnetic compass reads approx. correct at Senaki (2016) 88°M / 94°T while the RI Compass Repeater and Gyro Compass read 115° and 122° respectively.

 

 

I haven't found any details on the Mossie's RI Compass Repeater to find out if it's Master Compass is similar to the Bf-109's PFK/m

 

I think ED are modelling "Magnetic Dip" which effect magnetic compasses under acceleration or in a turn, however it shouldn't effect them when stationary or in non-accelerated level flight.

 

Magnetic Compass Errors - Acceleration

 

 

Magnetic Compass Errors - Turns

 

 

 

 

Edited October 5, 2021 by Ramsay

[Ramsay]

On 10/5/2021 at 5:17 PM, Ramsay said:

I haven't found any details on the Mossie's RI Compass Repeater to find out if it's Master Compass is similar to the Bf-109's PFK/m

 

Still haven't found anything specific but am thinking ED might have modelled the mossie as using a Bendix Flux Gate compass or perhaps the simpler Magnesyn Compass ?

 

 

If so, AFAIK it shouldn't show errors due "magnetic dip", acceleration, etc.

 

Re: The Magnesyn Compass

 

Think the base non-gyro stabilised, oil damped Magnesyn Compass still shows errors but they are reduced from those found with a "normal" magnetic compass. It's floating compass has 20° of freedom of movement, so I would expect it also to read accurately when stationary or in unaccelerated level flight.

 

Edited October 6, 2021 by Ramsay
Read up on the Bendix Magnesyn R.I. Compass

[Nealius]

8 hours ago, Ramsay said:

I haven't seen the issue with the base magnetic compass (Spitfire is hard to read) but the Mosquito and Spitfire Gyro Compasses are set "wrong" when spawning.

 

That's interesting. I've been playing The Big Show a lot recently and the Spit's gyro compass always matches my true heading at spawn. When I set the magnetic compass it's always 20 degrees off of true, when in Normandy/Channel 1944 it should only be off by 10 degrees. 

 

I found the Mossie's compass to be off here, and it's marked as a known issue now: 

 

[Ramsay]

15 minutes ago, Nealius said:

When I set the magnetic compass it's always 20 degrees off of true, when in Normandy/Channel 1944 it should only be off by 10 degrees. 

 

I've always found compass behaviour inconsistent in the WWII maps, but couldn't tell if it was an issue with the map, the aircraft or a misunderstanding about the "correct" historic magnetic deviation on my part.

I also have to admit to not noticing the problem on the modern Caucasus map as I usually (always?) fly the WWII warbirds using visual landmarks and only used the compass for the most basic of SA i.e. which way to look for a particular landmark, etc.

 

So when looking at your initial reports, I certainly didn't expect to find such a pervasive problem or that Chuck's Guides for the FW190D-9 and BF-109K-4 from July 2019 would show the problem has been present at least since then.

 

On the positive side, ED have marked it as a "known" issue 

[Nealius]

Yeah hopefully they will get fixed soon. Prior to flying Reflected's campaigns and the Mossie I was also flying off landmarks, but now I've needed more reliance on a working compass to get to my objectives and back.