Whine of turbines, some rotor noise, increasing in intensity and speed of rotors, until chopper takes off ...
Screeching air as an arrow whizzes by.
Screaming bomb whistles with an rocket explosion.
Gentle windy whooshing like sound. Flap or large fan blade.
Single propeller light aeroplane, fast pass by
Small light aircraft propeller, medium speed pass by
Long electronic helicopter sequence fluttering in and out
Various high pitch tones modulating randomly