CONKERS ======= An independent reimplementation of the British playground game "conkers" as a physics simulation, built for the SkillSafe platform. THE ORIGINAL ------------ Conkers is a traditional children's game with no author and no owner. It is played with the seed of the horse chestnut, Aesculus hippocastanum, drilled and threaded on a lace. The first recorded game played with horse chestnuts is dated to the Isle of Wight in 1848 (Opie & Opie, "Children's Games in Street and Playground", Oxford: Clarendon, 1969, p. 232, as cited by Wikipedia; the book itself was not available to read). Robert Southey's memoirs, published 1821, describe the game played with snail shells and hazelnuts. The competitive rules paraphrased in this app are published by the ORGANISERS OF THE WORLD CONKER CHAMPIONSHIPS, run by the Ashton Conker Club, founded 1965 by a group of anglers at the Chequered Skipper public house in Ashton, Northamptonshire, England; now held at the Shuckburgh Arms, Southwick, on the second Sunday in October. The championships have raised over GBP 485,000 for causes supporting the visually impaired. https://worldconkerchampionships.com/compete/rules/ THIS APP IS NOT AFFILIATED WITH the World Conker Championships, the Ashton Conker Club, the Shuckburgh Arms, or any other conker organisation, and carries none of their branding. The ten rules are paraphrased in the app's own words and attributed. "Conker" is also an unrelated Rare/Microsoft video-game franchise; this app has nothing to do with it either. WHAT IS FAITHFUL ---------------- - All ten current championship rules are reproduced, in paraphrase, with attribution, in the Rules & about panel. - The scoring rule is the documented inheriting variant: a winner's new score is its own score plus the defeated conker's score plus one. A new conker is a "none-er"; one win makes it a "one-er". - The 20 cm minimum lace, the three alternate strikes per turn, the three-snag disqualification, the five-minute rule and the nine-strike umpire's decision are all quoted as the organisers publish them. - The 30 mm competition conker width is used as the app's reference size, and is flagged as coming from the organisers' SUPERSEDED rules page rather than the live one. WHAT DIFFERS ------------ - One homogeneous brittle sphere with a hole, not a starchy cotyledon inside a glossy testa. That simplification is what makes the problem computable. - Every strike connects. There are no misses, so the five-minute rule and the Chief Umpire never come into play. - Snags, re-threading and the three-rejection blind draw are described but not simulated. - At the championship you never bring your own conker (rule 1). Here you choose yours, which is the playground game rather than the competition. - "Stamps" are not implemented. The championships ban them, and say so on the grounds that stamping favours strength and physique. - The non-inheriting scoring variant ("one point flat") is not offered. WHAT IS MODELLED, AND HOW HONESTLY ---------------------------------- DOCUMENTED Hertzian contact mechanics; the contact-edge tension (1-2nu)p0/3; the Weibull distribution (Weibull, "A Statistical Distribution Function of Wide Applicability", ASME J. Appl. Mech. 18(3), 293-297, September 1951 - read from the paper itself); the size law sigma1/sigma2 = (V2/V1)^(1/m) (Quinn & Quinn 2010, Dental Materials 26:135-147 Eq. 5, NIST copy; Shin & Jang 2019, Front. Mater. 6:289 Eq. 5); the flaw-tail relation m = 2n-2 (Jayatilaka & Trustrum 1977). NOTE: Weibull 1951 does NOT state the volume-scaling law. It gives the weakest-link form the law follows from, and the word "volume" does not appear. The app cites it only for the distribution. DERIVED The impact-duration prefactor, obtained here from a Beta function as 2.9432752 d_max/v = 2.8682657 (m*^2/(R* E*^2))^(1/5) v^(-1/5), which reproduces the 2.87 quoted in the contact-mechanics literature; the size-mismatch factor (1+s)^2/(1-s+s^2) and its maximum of 4 at s=1; the duel exponent 2m-3 and its crossover at m = 3/2. CALIBRATED Density, modulus, flaw densities and the flaw-severity scale. Chosen so a duel lasts about a dozen strikes. RECONSTRUCTED The sub-critical damage rule, the chip-to-bulk-flaw coupling, and all five seasoning settings. UNSOURCED The mass of a conker; the strength, stiffness, toughness or Weibull modulus of a horse chestnut seed; ANY measurement of whether baking, vinegar, seasoning or varnish does anything at all. None of these exists. Europe PMC, OpenAlex, Crossref and arXiv return nothing on conker mechanics, and no controlled test of hardening has ever been published. The app reports these as gaps rather than filling them in. BUILD ----- Written from scratch: the physics engine, the 2D canvas renderer, the charts and the flaw-population simulator. No framework, no CDN, no external script, stylesheet, font or image. Nothing is fetched at runtime; the app never calls a model and costs nothing to run. Licence: see LICENSE.txt.