Dplus$, check PM.
App. topple is 15 · cos(lat) per hour.
App. drift is 15 · sin(lat) per hour.
Transport wander is (E/W GS · tan(lat))/60 per hour.
(GS being groundspeed)
Simple table I was taught is:
NH SH
RW ±° ±° [as given]
ER - + [15 · sin(mean lat)]
LN + - [15 · sin(lat as set)]
TWE - + [E GS/60 · tan(mean lat)]
TWW + - [W GS/60 · tan(mean lat)]
PER HOUR.
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[edit]
LR, for all his shortcomings Eric was a brilliant teacher and a very inspiring fellow. Article he wrote in '74 here,
http://www.gyroscopes.org/papers/The...0umbrellas.pdf