Overview
- In tests reported Aug. 9–10, UK engineer Tom Stanton used a 40 kg counterweight and a redesigned drum to spin a carbon-fiber arm to about 2,342 rpm and launch a roughly 4-gram projectile at a calculated 346.4 m/s.
- The system uses a 3:1 pulley/drum arrangement that increases the effective drop height to about 1.9 meters and shifts torque during the winddown so the arm gains extra rotational speed.
- Stanton times release mechanically with a latch inside the drum so the sling unwraps within a tiny window of roughly 0.0025 seconds to catch the arm at peak speed.
- Earlier runs with heavier weights produced component failures, so Stanton lightened the projectile, changed the drum taper, and strengthened parts before the final run that produced an audible sonic 'crack' consistent with breaking the sound barrier.
- Reporters note measurement and robustness caveats because the supersonic speed is calculated from rpm and high-speed footage and earlier failures show the design still strains components even when a run succeeds.