To any students who want to do a 40 deg turn into base as normal procedure, I hope your life insurance is paid up. That's bordering on a steep turn, not medium.
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Extract from the FAA Airplane Flying Handbook - sub heading "Basic Flying Maneuvers"
For purposes of this discussion, turns are divided into three classes: shallow turns, medium turns, and steep turns.
* Shallow turns are those in which the bank (less than approximately 20°) is so shallow that the inherent lateral stability of the airplane is acting to level the wings unless some aileron is applied to maintain the bank.
* Medium turns are those resulting from a degree of bank (approximately 20° to 45°) at which the airplane remains at a constant bank.
* Steep turns are those resulting from a degree of bank (45° or more) at which the "overbanking tendency" of an airplane overcomes stability, and the bank increases unless aileron is applied to prevent it.