Directional gyro and compas fail

[nehmo]

I have noticed that the Directional gyro, freezes or shows random directions, not in line with the direction of flight. When changing the direction of flight, it only moves a few degrees and stop rotate.

The compass, however, does not work at all. It always points north.

 

[PL_Harpoon]

1 hour ago, nehmo said:

The compass, however, does not work at all. It always points north.

The compass does not rotate. The thin needle shows your heading.

[PL_Harpoon]

After some more tests I think they are not behaving how they should.

The compass in the middle is directly linked to the magnetic compass so the needle should act just like one i.e. be sensitive to bank and turning errors. Instead, as @nehmo said, it just freezes when banking > 60 deg or possibly also above certain Gs. There are no errors up to 60 deg of bank.

The gyro, instead of working like any other directional gyro in DCS (and most likely IRL too) also just freezes at exactly the same conditions. What it should do instead is slowly drift during normal flight or quickly drift during hard maneuvers or if there's not enough air.

[wraith444]

This may not be related to what you're experiencing, but apparently the directional gyro is only supposed to be good up to 55 degrees bank or pitch. If that's modeled, I'd expect it to fail at more severe attitudes and need to be caged, corrected, then uncaged (since you can't correct it while it's uncaged).

[PL_Harpoon]

About the gyro

I did some research and apparently it really should only work up to 55 degrees pitch/bank. I'm not sure it would freeze above that though. The gyro is still spinning at those angles, it's just that the pitch/roll gimbals cannot rotate further. My guess is that it should still rotate but "wrong". How wrong, I don't know - I tried to simulate the gimbals in 3d software but so fat wasn't able.

BTW, the P-51 we have in DCS is supposed to have the same gyro as the Corsair and it doesn't behave that way.

 

Regardless. the compass is still working incorrectly though.

[nehmo]

On 6/23/2025 at 8:50 AM, nehmo said:

The compass, however, does not work at all. It always points north.

Ok. My fault. I didn't understand how compass works.

Regarding to  gyro. It works fine to 55 deg bank. After that freezes. Understand that it is build this way, but if I straighten the flight, the gyro should quickly return to the correct direction display. This is how it works in P51 and Spitfire. 

Currently gyro is showing direction changes from the freeze position. For example, the compass shows E and the gyro S.

[PL_Harpoon]

Thing is, I'm not sure the gyro should freeze when past 55 degrees. 

What's more strange is that from what I've found all US fighters we have in DCS use the same instrument: AN-5735 which is limited to +/- 55 deg bank/pitch but it behaves differently in all modules:

P-51 - as stable as a modern instrument: doesn't drift, doesn't stop

P-47 - slowly drifts above 55 degrees but can be rotated while uncaged. Despite that it has the best "feeling" of the three.

[450Devil]

Here is an extract from the Corsair Pilot Notes giving the limitation for the Gyro Horizon and Directional Gyro.