Revised station A. Three straight, ribbed bronze pipes draw air from a calm base chamber and discharge it into the throats of three brimmed rings. The tallest pipe stands on the centre line at the front and the two shorter ones to either side, so every ring has clear air in front and behind. The intake spine stands at the back, its cowl arching forward over the top to face the wind. The cluster turns on one bearing near its front, and the drag of everything behind the bearing steers it into the wind.
Ring suction and intake pressure together put about three times the wind's dynamic pressure across the pipes. That is enough to make them whistle from roughly 13–20 km/h. As a gust builds, each pipe jumps up its own harmonic series and falls back as it passes.
Each row is one pipe's harmonic series. Shaded cells can start at the present air speed, and the copper cell is sounding. Pause on a cell for the wind range in which it starts; click it to hear that harmonic alone.
The wall is a stack of silicon-bronze rings: thin crest rings with a 24 mm bore, alternating with spacers that leave a 4 mm groove 3.5 mm deep. This is the tested geometry. Air sliding across each groove sheds a small vortex per cycle, and the pipe's standing wave paces all of them together.
Onset speeds, the Strouhal window and friction come from measurements on stationary and swung corrugated pipes. The ring speed-up (1.75× expected, 1.5× cautious) is an estimate from diffuser theory and the wind-lens power data, not a measurement. Loudness is a first-order radiation estimate, ±6 dB.
About 80% that, as specified, all three pipes sing by 25–28 km/h at head height and step through 2–3 notes per gust, in dry weather or drizzle. The page runs single cases, not that spread. The cautious case shows the slow end.
Largest uncertainties: how much suction the rings give in gusty, shifting wind; and how the chamber and the ring outlets change the pipes' resonances. Wet grooves (fog, condensation, driven rain) are not modelled and may silence the pipes. The ribbed length must stay dead straight: a 35° bend silenced the swung Hummer.
Loudness: about 60–68 dB at 1.5 m per pipe at the default limit, louder than the reed column. The limiter is the main control; lowering it keeps the pipes on their first notes.
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