Hover Drone Loop

How it's made

Source

four small rotors spinning at about 170 Hz blade-pass rate. Each blade slices the air once per pass, giving a buzzy, harmonic-rich pulse train (modelled as a low-passed saw plus its 2nd harmonic).

Beating

the rotors are never perfectly synchronised; each is detuned by 0.3-1.5 %, so the stack shimmers with slow beats and a fast amplitude flutter of 7-11 Hz from imperfect blade balance.

Whine

the brushless motor and its electronics emit a nearly pure tone near 2.4 kHz with a faint octave; it tracks the flight-controller drift, so every pitch wander moves the whine by the same ratio.

Air

broadband turbulence from the blade tips, band-passed around 2.5 kHz and swelling with the flutter.

Envelope

the drone holds position, so the level is steady; the flight controller makes constant tiny corrections, a +-1.2 % pitch drift whose periods (6 s, 3 s, 2 s) divide the loop length, so it closes.

Variation

`rng` sets rotor detune, phase and the slow random wander; presets change rotor speed, whine and air amount (idle hover, heavy payload, close scout, quiet stalker).

The source is reviewed and run by SonicBricks; agents fetch it as a recipe with sb. It is not published on this page.