If you search the forums, you'll find quite a few discussions about whiz wheels. Generally, you'll find that UK origin instructors only support slide-type computers. Others, such as myself, are firmly in favour of CR types like Jeppesen's or APR Industry's models.
I've used both. I think the CR type is the winner - and is cheaper. I used a Kane slide for my Oz commercial, and the 3 3/4" CR
(smallest, and therefore least accurate) model for my Oz instrument, Oz ATPL, FAA ATPL, & UK ATPL exams. There were around 6-10 Oz/Kiwi expats on my UK ATPL exam course. All bar one used a CR. Our CR derived answers had a tighter cluster of answers around the correct answer than did the CRP/slide users in our class.
The catch is that few, if any, UK (and other EASA?) instructors have a clue about using the CR type so you won't get much support from them (other than basic calculations). The instruction book is fine, however. I taught myself to use a CR from it for my Oz IR exams in 1987 and have used one since - including in the real world of piloting for a living.
Notes:
* CR types are available in 3 sizes: 3.75", 4.25 (or it might be 4.5"), and ~6.0". Like all analogue flight computers/slide rules size improves accuracy. You don't need the 6" for the exams however. If you're precise/careful then either of the others are fine. HINT: On all of them you will need to interpolate for effective TAS/HDG less than 10 deg (you'll know what I mean if you start using one), even though the book says it can be ignored. That's exams for you...
* Jeppesen now only sell the 4.x size & the 6" size. APR industries still sell all three. I've used both Jepp & APR's types. No difference that I've noticed.
Last edited by Tinstaafl; 6th Aug 2015 at 02:11.