A dirty mind is helping me get through NAV, and my ppl generally for that matter.
To calculate drift: -
"Why does lorraine slip down low, tongue licking"
Why & Does = Wind Direction
Lorraine = set circle on top of horizontal wind line
Slip = plot speed, and slip up to TAS, slip wheel to track.
Down low = dot left
Tongue Licking = turn wheel left
So wind speed is 090 @ 10
1, set wind direction @ 090
2, set circle on line
3, set wind speed @ 10, slip up to tas, say 90, slip wheel to track say 040
4, dot is left, turn wheel left by drift amount, in this case the heading will be 046
Hope it helps
W line