https://matteocampagna.com/en/registry/equipment/thinner-shaft-air-drag Changes to this claim in Matteo Campagna's evidence registry: its status, its year-by-year history, revisions of the page. en-gb https://matteocampagna.com/en/registry/equipment/thinner-shaft-air-dragNobody has measured the force with which the air slows shafts of different diameter: there is only an inference from another figure. In a magnetic suspension wind tunnel, where the arrow is held in the air with no supports to disturb the flow, two competition shafts of different slenderness were compared without vanes: the barrelled A/C/E and the thinner, more elongated X10, tested on a cylindrical model one and a half times life size. At the same Reynolds number the drag coefficient, that is the force referred to the shaft's cross-section, came out the same for both, even though cylinder theory predicted a higher one for the X10. If the coefficient does not change, the force slowing the shaft grows with cross-section, so the thinner one should receive less. The force itself is not reported, though, the comparison holds for shafts without vanes and at lower Reynolds numbers than in a competition shot, and the authors themselves put the matching coefficients down partly to the way they calculated the mean cross-section of the barrelled shaft. A calculation on crosswind starts from the same idea, a push proportional to the exposed surface, and finds that a 5.24-millimetre competition arrow receives about two thirds of the push on a 7.5-millimetre training arrow. How far the arrow drifts, however, also depends on mass and flight time, which do not come into this.claim:asta-sottile-resistenza-aria:revision:2026-04-20:2Mon, 20 Apr 2026 08:00:00 GMT https://matteocampagna.com/en/registry/equipment/thinner-shaft-air-dragclaim:asta-sottile-resistenza-aria:new_claim:2026-03-25:non_studiatoWed, 25 Mar 2026 08:00:00 GMT