The following failures are disabled and will not happen in beginner
mode:
* engine flameout if too hot
* flaps, gear, canopy torn off if extended above certain speeds
* gear torn off if weight on wheels and not on runway (e.g. grass)
* gear torn off if landing too hard
* gear stuck (cannot be retracted) if extended above a certain speed
(but some other failures can still happen...)
Use the MiG-15bis menu to choose between "beginner mode" and the
default "pilot mode".
