KM-2 magdec entry required?

[some1]

14 hours ago, Razorback said:

My second question : do you change the latitude on the KM-2 when you are flyning on Caucasus, Syria or other maps ?

The latitude setting is there, because the gyro drift caused by Earth rotation can be calculated and cancelled by the gyro mechanism. The drift is 15 * sin(latitude) per hour. 

No idea if that's simulated in DCS or not.

Of course it does take into account the random wandering due to gyro imperfection.

[randomTOTEN]

It's simulated.

[Razorback]

When reading IRL manual, you can read these informations :

MK is the primary operating mode of the system and is recommanded when flying in latitudes HIGHER than 70 degrees (NORTH POLE)

The GA-6 gyro as a cumulative error of 3° per hour!
The system must be calibrated periodically by switching back to MK (Magnetic Compass Mode) allowing the system to returning to the GPK (Directional Gyro Mode)

So, I as understand, the normal position during flight is on GPK (GYRO) even more on the DCS map (Caucasus, Syria,...)

Edited February 8, 2023 by Razorback

[admiki]

Yes, but I found out it will error up to 30 degs after combat jinking all over the AO. I just keep it in MK

[AeriaGloria]

16 hours ago, Razorback said:

When reading IRL manual, you can read these informations :

MK is the primary operating mode of the system and is recommanded when flying in latitudes HIGHER than 70 degrees (NORTH POLE)

The GA-6 gyro as a cumulative error of 3° per hour!
The system must be calibrated periodically by switching back to MK (Magnetic Compass Mode) allowing the system to returning to the GPK (Directional Gyro Mode)

So, I as understand, the normal position during flight is on GPK (GYRO) even more on the DCS map (Caucasus, Syria,...)

 

Which part of which manual? The South American and Soviet manuals I have only mention using MH/MK mode and syncing/matching when starting up and making sure it aligns with take off heading. Emergency procedures also only mention MH mode. 
 

I have a Mi-35M manual I obviously can’t share, it uses identical Greben and KM-2 system. For start up it also says to set to MH mode and slave and leave it there, but has an additional note I will quote from Section 1.11.14 in case you have it 

“Note: the mode DG should be used at flights in the northern and southern latitudes over the magnetic anomaly zones.” 

Which makes it sound to me it’s more of a backup mode when magnetic correction would only increase errors 

Edited February 9, 2023 by AeriaGloria

[Razorback]

There are more information in the Mi-17 manual compared to the one related to the Mi-24/35

[some1]

21 hours ago, Razorback said:

MK is the primary operating mode of the system and is recommanded when flying in latitudes HIGHER than 70 degrees (NORTH POLE)

The image you posted above says that GPK is recommended for high latitudes, not MK. This applies to all aircraft, as magnetic compass readings become unreliable there, while bearings are changing quickly over relatively small distances due to basic geometry.

In other parts of the world, that may depend on where you fly, for how long, and how good and reliable is the flux detector installed in the aircraft. But for our flying in DCS, GPK doesn't really bring anything to the table, except for more risk for accumulating errors. It's better to set it to MK and forget about it. 

Edited February 9, 2023 by some1

[Razorback]

11 minutes ago, some1 said:

The image you posted above says that GPK is recommended for high latitudes, not MK. This applies to all aircraft, as magnetic compass readings become unreliable there, while bearings are changing quickly over relatively small distances due to basic geometry.

In other parts of the world, that may depend on where you fly, for how long, and how good and reliable is the flux detector installed in the aircraft. But for our flying in DCS, GPK doesn't really bring anything to the table, except for more risk for accumulating errors. It's better to set it to MK and forget about it. 

 

Yep indeed but than why in the WARNING note the opposite is explained...
Yesterday, I tested this setting during a long flight (Greben on GPK) and it was very accurate. Only switching to MK for a calibation and then back to GPK.
The question is : is it a real difference in DCS if you decide to choose for MK or DPK?

[admiki]

31 minutes ago, Razorback said:

Yep indeed but than why in the WARNING note the opposite is explained...
Yesterday, I tested this setting during a long flight (Greben on GPK) and it was very accurate. Only switching to MK for a calibation and then back to GPK.
The question is : is it a real difference in DCS if you decide to choose for MK or DPK?

As I said above, yes.

For general flying it's no big deal, but when you introduce combat flying, you can get errors up to 30 degs by mission end. Just leave it in MK

[AeriaGloria]

8 hours ago, Razorback said:

Yep indeed but than why in the WARNING note the opposite is explained...
Yesterday, I tested this setting during a long flight (Greben on GPK) and it was very accurate. Only switching to MK for a calibation and then back to GPK.
The question is : is it a real difference in DCS if you decide to choose for MK or DPK?

Yes Gyro will give you errors. I have read that part of the Mi-17 manual and while similar the units are slightly different. Mi-8/17 uses GA-6, Mi-24 uses GA-8 and along with KM-2 and PU-38 appears to be a slightly more mature system.

One difference appears to be that while Mi-8/17 manuals, including DCS say to initialize in MK and switch to gyro before take off, Mi-24 manuals say to only keep it in MK unless flying at high latitude or near anomaly. To me that seems like a clear operational difference coming from the differences between the older compass system of the Mi-8/17, and the more mature GA-8 and Greben system of Mi-24 

Another difference for example, the error of the system in gyro mode is +/-1 degree in gyro mode in good conditions. 
 

There is also an English translated section that mentions both gyro and MK mode can be used for normal operations, but if you follow procedure you stick with MK

Edited February 9, 2023 by AeriaGloria