Magnetic Variation

[Rubberduck85]

Hi,

 

I have a question for experts in Viper's avionics.

 

From the last patch:

 

* MAG VAR will now switch between AUT and MAN by use of the SEQ position of DCS switch.

 

After finding the corresponding section in the ICP I was able to set magnetic Variation to manual and input some values, with the logic of East /West and 3 digits. The effect was that the compass tape on the hud adjusted accordingly.

 

However I do not understand the need of this, I'll explain myself better:

I was under the impression that by default the shown heading is always true and not magnetic. And it is done accordingly with the map (Caucasus 6.7 and PG 2.2, give or take)

 

What is the difference between auto and manual?

 

Sent from my Xiaomi MI8

[Flamin_Squirrel]

Default heading is always magnetic. Not sure about the rest.

[Frederf]

You don't need it. By default the airplane automatically discovers magvar by comparing the INS gyrocompass heading with the magnetoflux compass. I.e. it starts in auto. The shown heading in most displays is magnetic. The INS true heading will be given the label "THDG" on the INS page.

 

Automatic discovers the value automatically. Manual allows pilot entry.

 

What you might be confused about is thinking about other airplanes like the L-39 that have a magnetic field sensor and rely on an input magvar value in order to display true heading. Western INS-based airplanes are the exact opposite, discovering true heading gyroscopically but preferring to display magnetic. In an L-39, MiG-21, etc. if you have a zero correction everything displays magnetic. In a Harrier, Hornet, Viper, Eagle if your correction is zero everything displays true.

[Rubberduck85]

You don't need it. By default the airplane automatically discovers magvar by comparing the INS gyrocompass heading with the magnetoflux compass. I.e. it starts in auto. The shown heading in most displays is magnetic. The INS true heading will be given the label "THDG" on the INS page.

 

Automatic discovers the value automatically. Manual allows pilot entry.

 

What you might be confused about is thinking about other airplanes like the L-39 that have a magnetic field sensor and rely on an input magvar value in order to display true heading. Western INS-based airplanes are the exact opposite, discovering true heading gyroscopically but preferring to display magnetic. In an L-39, MiG-21, etc. if you have a zero correction everything displays magnetic. In a Harrier, Hornet, Viper, Eagle if your correction is zero everything displays true.

Thank you so much!

 

Sent from my Xiaomi MI8