AH-64 1.1 DEVELOPMENT ROTOR (2026-09-26)

Runtime asset: sfxAH64RotorHoverGrounded.wav
Title: Helicopter Sounds
Creator: aquinn
License: CC0, verified on the original source page 2026-09-26
Source: https://opengameart.org/content/helicopter-sounds
Original download: https://opengameart.org/sites/default/files/helicopter_0.mp3
Prepared loop: https://github.com/johnstonstu/Dust-Front/blob/main/assets/audio/rotor_loop.wav
Git blob: 518b52baf94acde3facc514b1f9239ae069915ab
SHA-256: BD70EB8AE5A472018AB75F3212395826B01E07BBFCB5EBECB29952B943FC6B36

Dust Front cropped a steady segment, normalized and crossfaded it for looping.
Original preserved at Art/Audio/rotor-aquinn-original.wav (outside Unity).
Candidate B, 2026-09-26: tools/prepare_rotor.py applies a 35 Hz rumble cut,
broad +6 dB low shelf and gentle 3.5 kHz treble rolloff, then normalizes the
peak to -1 dBFS. No added pulse train; natural blade timing is preserved.
Prepared SHA-256: DA89EE5B3EE0CBC602506BBCFA393AFAC69E58BEA143B11AE8C70DC2068E78C4
Format unchanged: 44.1 kHz, mono, 16-bit PCM, 131418 frames.
Measured RMS -10.94 dBFS; low/high band energy ratio increases 7.29 dB.
Unity imports PCM at the original rate. Runtime controls gain, pitch and cutoff.
This replaces the qubodup hover WAV described below. The two legacy movement
clips remain bundled for now, but the 1.1 audio driver plays only this loop.

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LEGACY 1.0 GROUNDED ROTOR HOVER BED (provenance retained)

Runtime asset:
sfxAH64RotorHoverGrounded.wav
(was sfxAH64RotorHoverGrounded.mp3 until 2026-08-03; the mp3 is retained
unmodified at Assets/AH64Archive/ as the provenance original.
The shipped WAV is that same audio with the MP3 encoder's 45ms leading and 15ms
trailing padding trimmed off, plus a 3ms fade at each cut edge. The padding made
the loop go silent for 60ms every 6.38s. Same source, same licence - no new
material was introduced.)

Title: Helicopter Rotor Loop
Creator: qubodup
Original source:
https://freesound.org/people/qubodup/sounds/187681/
Distribution source:
https://pixabay.com/sound-effects/city-helicopter-rotor-loop-105796/

License:
Creative Commons Zero (CC0 / public domain) on the original Freesound page.
The distribution page also identifies the download as available under the
Pixabay Content License. Game use, modification, and redistribution as part of
this mod are permitted. Attribution is not required, but this record is retained
for provenance.

Retrieved: 2026-07-30
SHA-256:
CA58E5FA8838F8B17DB5D7616C550DAD936DF9CE5857DC0A1F5B5C8DABC58955

Integration decision:
Approved as the sole continuous hover-bed source for 0.1.1. The alternative
Chinook/high-wind rotor-slap audition was explicitly rejected and is not copied
into runtime assets. Runtime playback starts at a deliberately conservative
volume because the unprocessed source is intense. Speed/collective layers are
reserved for a later mix pass.

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AH-64 MOVEMENT LAYERS (added 2026-08-03)

Runtime asset:
sfxAH64RotorInFlight.mp3

Title: Helicopter Loop
Creator: qubodup
Source: https://freesound.org/people/qubodup/sounds/187678/
License: CC0 (public domain), same US-government-sourced pack as the grounded
bed above. Fuller engine+rotor blend than the grounded loop; fades in with
horizontal speed to read as forward flight.

Runtime asset:
sfxAH64RotorClimb.mp3

Title: OH-58 Helicopter Loop
Creator: qubodup
Source: https://freesound.org/people/qubodup/sounds/184412/
License: CC0 (public domain), same pack. Lighter tone than the AH-64 bed;
used purely as a texture layer that fades in with climb intent (collective
input / ascent), not as a realism claim about the OH-58.

Both retrieved as Freesound's own 192kbps preview encode (no login available
in the session that added them) — swap for the full-quality FLAC from the
source pages above if a cleaner master is wanted before a public release.
