Field card: Equipment and tuning
An A4 sheet to take to the range: the terms that recur in the studies in this domain, with a one-line definition, and the registry claims that are currently corroborated, contested, contradicted or refuted.
It fits on a single A4 sheet. You can also print with Ctrl+P, or Cmd+P on a Mac.
Terms
- Draw weight
- The draw force of the bow, in pounds: on bows without cams it is the force at full draw, on a compound the peak force.
- Riser and limbs
- The riser is the central body of the bow, with the grip, sight window and fittings; the limbs are the two blades that bend and store the energy.
- Static and dynamic spine
- Spine is the stiffness of the shaft.
- Vanes, feathers and Spin Wings
- The surfaces glued at the back of the arrow that bring it back into line with the airflow.
- Stabilisers, side rods and TFCs
- The long front stabiliser, the side rods mounted on a V-bar and TFCs.
- Shooting machine
- A rig that holds the bow, draws the string and releases it the same way every time.
- Release aid
- The device that holds the string in place of the fingers and lets it go with a trigger or a rotation of the hand.
- Archer's paradox
- The historical name for the fact that an arrow resting to one side of the bow, rather than at its centre, still flies where the archer aims.
- Wind tunnel and CFD
- Two ways of studying air resistance on the arrow.
- Chronograph
- The instrument that measures arrow speed from the time the arrow takes to pass between two sensors a known distance apart.
- Nocking point
- The spot on the string where the nock clips on, marked by brass or tied nock locators.
- Draw force curve
- The graph that links the force on the string to each point of the draw.
Claims
- Corroborated High-speed films of 16 world-level archers and of one national-team archer, plus bench tests: the shaft flexes sideways as it leaves the bow.
- Corroborated Since 2007 several laboratories have measured the arrow slowing: about 5 per cent over 14 metres, 8 over 55, around 15 over 70, depending on arrow and airflow.
- Contested At the Indian university championships recurve archers were 13 to 16 centimetres taller, with no test; in seven elite archers no difference shows.
- Contested In two theses on seven and six archers, the compound asks for more muscle work than the recurve early in the draw and for less after the let-off.
- Contested In three samples higher-level archers shoot four to nine pounds more, while in a fourth, draw weight does not separate the levels at all.
- Contested Readings of 30 to 40 lb come from small national-team groups; the larger samples of elite recurve archers sit higher, above 42 lb on average.
- Contested The marked draw weight holds at the reference draw length: 49 beginners pulled less than marked, six archers drawing about 28 inches nearly the same.
- Contested On a longbow replica the model predicted draw weight within 1%, but on a modern recurve it overshot, and measured efficiency was lower than predicted.
- Contested Flexing makes the air layer turbulent and raises an arrow's drag, but at recurve speeds it may be turbulent anyway, and the studies disagree.
- Contested Speed and length recur in every measurement; fifteen grams fits the A/C/E, while X10 arrows weighed on the bench sit between 19.7 and 21.2 grams.
- Contested The only measurement, on wooden arrows with natural feathers, finds helical fletching losing less speed than straight at two feather lengths, more at the third.
- Contested On material two tests agree: modern strings send the arrow off slightly faster.
- Contested One archer measured in 1992: with a 10 millimetre bite plate sway while aiming fell, with 2 and 5 millimetres it did not.
- Contested Across production arrows the straighter ones group better; across competition shafts all inside tolerance, straightness no longer explains the impact point.
- Contested A robot with redesigned fingers flexes the arrow as an archer does, but drag was more consistent with archers and has not been measured again.
- Contradicted In the only fatigue test the authors report no change, yet after 600,000 cycles the estimated stiffness rose in all three arrows tested.
- Contradicted In the calculations and in the only estimate on a compound the arrow stays below the instability threshold during the thrust, though the margin shrinks quickly.
- Contradicted In 49 beginners and eight experienced archers strength and draw weight did not go together; in six archers the correlation was positive but within chance.
- Contradicted A recurve model finds nocking point height forgiving: a millimetre barely changes how the arrow leaves the bow, while a centimetre shows up straight away.
- Contradicted At 35 metres, with a compound on a shooting machine, halving the arrow's oscillation left the group unchanged, still within 1.5 centimetres.