Alpha Six,

As "Rule of the Thumb" 10º is fine for typical fighter flight across the Channel on CloD map,
and simplifies players compensate readings (just add 10). wink

If one go bombing London in a He 111 leaving Tramecourt, a more precise value is welcome.
Desastersoft KG 54 campaign comes with a adjusted 8º (PDF) protractor.

Sokol1