Offers hundreds of clips, including some looping files that can be easily extended to 5 minutes.
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. 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. Offers hundreds of clips, including some looping files
A massive library of specific helicopter types (Huey, Apache, etc.) for more realistic or "solid" sound design. Offers hundreds of clips
You can find extended clips like a 5-minute, 29-second recording of a helicopter landing with cockpit radio on HookSounds .
Great for high-fidelity, curated flying and hovering sounds.