https://matteocampagna.com/en/registry/equipment/bow-energy-arrow-recoil-nock 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/bow-energy-arrow-recoil-nockThe full account exists for a single bow, a compound measured in the laboratory and published in 2015 as a preprint. The bow makes 71.0 joules available and the 20.6 gram arrow carries off 57.1, or 80 per cent. The author attributes the rest, almost 14 joules, to the parts of the bow that move with the string: he does not measure it on its own but obtains it by difference, after showing that the other items are tiny. The bow's recoil, measured with an accelerometer, comes to 0.23 joules, pulling the nock off the string about 0.05, arrow oscillation and string shortening a few tenths of a joule each. Expressed as a virtual mass, it is as if the arrow dragged about 5 grams along with it, and half of those grams are in the string, the serving, the D-loop and the peep sight. The formula that follows stands up to the chronograph, since the speeds of three arrows of different mass fall on the predicted curve; two practical consequences, that a heavier arrow makes the bow more efficient and that a lighter string sends the arrow off faster, are deductions from the formula rather than separate measurements. The models reach the same picture by another route: in 1981 a calculation with an elastic string gave the arrow 78 per cent of the energy and left almost all the rest in the motion of limbs and string, with air resistance and hysteresis under 2 per cent, and in 1997 a model put the arrow's lateral motion at 0.05 of the drawn bow's 30.2 joules. There is one limitation, and it is a large one: one bow, one laboratory, one author, and the registry holds no matching measurement on a recurve.claim:efficienza-arco-energia-freccia:revision:2026-06-09:2Tue, 09 Jun 2026 08:00:00 GMT https://matteocampagna.com/en/registry/equipment/bow-energy-arrow-recoil-nockclaim:efficienza-arco-energia-freccia:new_claim:2026-05-04:riportatoMon, 04 May 2026 08:00:00 GMT