If you need much more than 5 minutes for background ambience or sleep, this 75-minute recording on SoundCloud offers a deep, immersive flying drone.
Great for high-fidelity, curated flying and hovering sounds. helicopter_sound_effect_flying_5_minutes
This YouTube video provides nearly 5 minutes of consistent flying sounds with a direct Free MP3 Download available in the description. If you need much more than 5 minutes