With a compound the arrow flexes less than with a recurve and leaves almost aligned
2 studies
The summary today
There is only one piece of work on it, a model of the arrow checked against photographs of a single bow, and the direction is clear. In 2011, on a single-cam compound mounted on a shooting machine, with ProTour 470 competition arrows, timed flash photographs and a model of the arrow as a flexible beam show that the greatest vertical flex, just before the arrow leaves the string, is a few millimetres, while with a recurve the author expects 10 to 15. The arrow leaves the rest at 14 milliseconds, the string at 17 and the bow at 20, and enters the airstream with an angle of attack of -0.4 degrees vertically and 0.1 horizontally, with minimal rotation about its centre of mass. Two limits keep the status low. The first is that the comparison with the recurve is not made in the same test: the 10 to 15 millimetres come from other work. The second is that the alignment depends on the tuning, the archer and the cams: moving the rest by 2 millimetres takes the horizontal angle from 0.1 to -0.2 degrees; twisting the bow changes the arrow's behaviour a great deal; with the nocking-point path of a binary-cam bow the model predicts markedly different behaviour, with a positive angle of attack; and in 2019 the same author writes that compound designs differ so much that a general rule is hard to give.
Also phrased as: "archer's paradox on a compound"; "compound arrows do not flex"; "arrow flex compound versus recurve"; "arrow leaving the bow aligned"; "release aid and arrow flex"
In practice
With a compound and a release aid the archer's paradox is said to almost disappear: the string travels straight, the arrow bends little and tuning is done on the rest more than on spine.
Evidence
-
2011
For Model Published later
Single-cam compound on a shooting machine, ProTour 470 arrows, a model of the arrow as a flexible beam compared with timed flash photographs: the greatest vertical flex, towards the end of the power stroke and just before the arrow leaves the string, is a few millimetres, while for a recurve the author expects 10 to 15. The arrow leaves the rest at about 14 milliseconds, the string at 17 to 17.5 and clears the bow at 20, at 78.2 metres per second. It enters the airstream with an angle of attack of -0.4 degrees vertically and 0.1 horizontally, with a rotation about the centre of mass of about -0.01 and -0.05 degrees per millisecond; moving the rest by 2 millimetres takes the horizontal angle from 0.1 to -0.2 degrees. With the nocking-point path of a binary-cam bow, calculated only, the predicted behaviour is markedly different and the angle of attack becomes positive. The recurve figure is not measured in the same test. The photographs serve to check the model on a single bow: the claim counts it as a model, as the source file does.
The Behaviour of An Arrow Shot from a Compound Archery Bow · J L Park
-
2019
Context Review Published later
Review of target archery by the same author: the measurements show that from a well-tuned modern compound the arrow leaves with small flex and small pitch and yaw angles, and that from a well-tuned recurve it leaves with a significant lateral flex amplitude and little vertical flex. Among compounds, though, design differences make a general rule for predicting flex and exit angles hard to give.
The impact of the atmosphere on target archery · James L Park
Status history
- 2011 Transferred The first work on the compound arrow follows it with a model and with timed flash photographs on the same bow, a single-cam compound mounted on a shooting machine: the greatest vertical flex before exit is a few millimetres, against the 10 to 15 the author expects with a recurve, and the arrow enters the airstream with an angle of attack of a few tenths of a degree and minimal rotation about its centre of mass. The alignment, however, depends on tuning, since 2 millimetres of rest are enough to flip the sign of the horizontal angle, and on how much the archer twists the bow. It is a model checked on a single bow, with the recurve benchmark taken from other studies: with the model alone the status is transferred.
- 2019 Transferred A review by the same author brings the measurements back together: from a well-tuned modern compound the arrow leaves with little flex and small pitch and yaw angles, while from a well-tuned recurve it leaves with a significant lateral flex amplitude and little vertical flex. It adds, though, that compound designs differ so much that a general rule for predicting flex and exit angles is hard to give. It brings no new measurements and does not compare the two kinds of equipment in the same test: the status stays transferred.
Related
Related articles
- The archer's paradox: the physics of the flexing arrowAt full draw the arrow points to one side and still reaches the centre: how it flexes and clears the riser in the first twenty milliseconds, and how spine matches it to the bow.
- The compound on the draw: what the cams, the limbs and the nocking point doCompound cams, limbs and nocking point: what shapes the force-draw curve, the let-off and the path of the nock, according to what studies have measured.
- Barebow / instinctive vs Olympic recurve vs compound: differences in the shot, the equipment and the scoreRecurve, compound and shooting without a sight compared: draw weight, arrow speed and flex, let-off, balance, scoring and injuries in the registry's data.
Research lines
Cite
Campagna, M. (2026). With a compound the arrow flexes less than with a recurve and leaves almost aligned (Version 2). In Evidence Registry. Retrieved 16 October 2026, from https://matteocampagna.com/en/registry/equipment/compound-arrow-flexes-less
@misc{campagna2026_compoundfrecciaflessioneminore,
author = {Campagna, Matteo},
title = {With a compound the arrow flexes less than with a recurve and leaves almost aligned},
year = {2026},
howpublished = {Evidence Registry, matteocampagna.com},
url = {https://matteocampagna.com/en/registry/equipment/compound-arrow-flexes-less},
note = {Version 2; accessed 2026-10-16}
}
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