The Knightson Computer
Looking at other threads (e.g. the recent one about PPL skills tests) I notice that most people's diversion planning seems to be done by mental dead reckoning or by using a whiz wheel in the cockpit (beats me how).
Why doesn't anyone ever mention the Knightson computer, which is an absolute doddle to use, as long as you remember to mark the wind on it before setting off? Is it just that Mr. Knightson is very bad at publicising his wonderful invention?