I can confirm that the CR 3 is probably the best - I've been using mine since the 70s and used it for my own CAA exams way back when. It even gives you sine/cosine values around the front face. An instrument well worth getting to know well, especially for the wind triangle calculations. So much quicker.
For information, this is from a student with a maths background who recently took the Nav exam:
"For the Nav I found that a number of questions did not offer the actual solution. I was using a Jep CR-3 computer which gives slightly different answers than theirs. I then did a spot check on a number of their problems solving them by trig. The trig is really only GCSE level (sin/cos/tan, and then the law of sines). What dumbfounded me was NONE of their answers were correct. I am at a complete loss of what to do with this. All the wind problems were Euclidian so really quite simple. Also, I don't use the 60-1 small angle approx since I had a calculator (and the CR3 does trig nicely) and they are very quick. Even with these simple ones, they did not have the exact answers, with the correct answers almost smack in between two others.
For my next attempt I am at a loss for what to do. If the "correct" answer is not correct, then what kind of arbitrary, "just happen to be the answer"are they looking for? Do they understand that in this simple math there is exactly one answer? Do they understand the difference between accuracy and precision? These too have tight definitions, but that seems to be lost on them. They seem to be happy with precision being that they all get around the same wrong answer, but either don't understand the simple math or don't care how to get accuracy. Unless they are going to specify the exact model of flight computer, to include the date of manufacturing since tolerances change, how can they do this? Perhaps I should send them ISO 5725."
Not good, is it?
Last edited by paco; 11th May 2013 at 03:06.