On a traditional bow without a sight, marks on the limb calculated for each distance can do the job of a sight

The summary today

There is a calculation, not a test. A 2023 Indonesian analytical model works out, distance by distance, where to draw a horizontal line on the upper limb that, lined up with the target, gives the right elevation. The inputs are the arrow's speed, how much it slows in flight, the draw length and the height of the eye above the nock, with a worked example at a 75-centimetre draw length and the eye ten centimetres higher. The same work shows how demanding the method is: at 70 metres, with an arrow at 60 metres per second, the right line sits at 20 millimetres, and misjudging the slowing moves it to 24 or 16, that is 35 centimetres below or 38 above the centre; misjudging the speed by 3 metres per second moves the hit by 69 to 80 centimetres. The height of the nock relative to the centre of the target also calls for a correction of a few millimetres. No archer has shot with these marks, and the model assumes an anchor that never changes and an eye always at the same height above the nock, which is exactly what varies in instinctive shooting. Nor does the paper say whether marks of this kind are allowed in competition, and anyone shooting in a division without a sight needs to check that in the rules they compete under. With a single model and no measurements, the status is "Transferred".

Also phrased as: "reference marks on the limb"; "aiming without a sight"; "sight lines on a traditional bow"; "distance marks on the bow"; "reference aiming with an instinctive bow"

Evidence

• 2023
  For Model Published later

  An analytical model with air drag proportional to the square of the speed: for each distance it calculates the position of a horizontal line on the upper limb that, lined up with the target, gives the right launch angle, starting from the arrow's speed, its slowing in flight, the draw length and the height of the eye above the nock. The curves are computed with the eye 10 centimetres above the nock, a 75-centimetre draw length and three drag conditions: none, 0.002 and 0.005 per metre. There are no shots at all: the abstract states that the method improves accuracy, but that is a claim of the model.

  Physics Application in Traditional Archery: Sight-lines Method for Aiming Using a Traditional Bow · Ibnu Jihad

• 2023
  Context Model Published later

  Sensitivity analysis of the same model at 70 metres, with an arrow at 60 metres per second and a slowing of 0.002 per metre: the right line sits at 20 millimetres. Estimating the slowing at 0.001 moves it to 24 millimetres and the arrow lands 35 centimetres below the centre; estimating it at 0.003 moves it to 16 and the arrow lands 38 centimetres above. Misjudging the speed by 3 metres per second moves the hit by 69 to 80 centimetres: 80 above when the arrow is slower, 69 below when it is faster.

  Physics Application in Traditional Archery: Sight-lines Method for Aiming Using a Traditional Bow · Ibnu Jihad

• 2023
  Context Model Published later

  In the same model the height of the nock relative to the centre of the target also counts, which the basic calculation puts at the same level, 130 centimetres: with the nock at 140 centimetres the hit rises by 10 centimetres and the line has to go up by 1 millimetre; for a youngster with the nock at 100 centimetres it has to come down by 3.

  Physics Application in Traditional Archery: Sight-lines Method for Aiming Using a Traditional Bow · Ibnu Jihad

Status history

1. 2023 Transferred The first work on the question arrives, and it is a calculation. An Indonesian analytical model works out, distance by distance, where to draw a horizontal line on the upper limb that, lined up with the target, gives the right elevation, starting from the arrow's speed, its slowing in flight, the draw length and the height of the eye above the nock. It also shows how precise the mark must be: at 70 metres, 4 millimetres too high or too low are worth 35 to 38 centimetres on the target. No archer has tried the marks on the range, and models alone stay transferred.

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Research lines

• 22 studiesTraditional and historical bows, from models to archers

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