On the longbow, the flatbow and the horse bow, draw force rises almost in a straight line up to 50 centimetres of draw
2 studies
The summary today
The only measurement comes from a group that in 2018 was building a haptic simulator of traditional archery and needed the force curve of three bows to reproduce: a replica recurve horse bow, a flatbow and an English longbow, all with Dacron strings. Taken on a dynamometer up to 50 centimetres of draw, they give curves the authors describe as close to a straight line, with slopes of 0.2498, 0.2837 and 0.3001. Three limits narrow its reach. The measurement stops at 50 centimetres, which the paper gives as the maximum draw used to shoot these replicas without saying where it is measured from: whether it covers the last few centimetres of an adult's draw, where a bow without cams can stiffen, cannot be told. The replicas have about a third of the draw weight of the historical bows. And the unit of force in the line is not stated, nor is there any index of how well the line fits the points. It does not apply to all traditional bows: for the Japanese yumi two models find a three-stage curve, rising fast, slowing and then climbing again.
Also phrased as: "longbow force-draw curve"; "pounds per inch on traditional bows"; "traditional bow stiffening at full draw"; "stacking"; "flatbow draw curve"
In practice
It is said that a longbow or flatbow comes back evenly, with the force rising by a few pounds for every inch, and that a well-made bow should not stack abruptly towards the end of the draw.
Evidence
-
2018
For Equipment tests Published later
Tinius Olsen dynamometer, Dacron strings, draw up to 50 centimetres: force follows F = a·x + b with a = 0.2498 and b = 3.60 for the horse bow, a = 0.2837 and b = 11.24 for the flatbow, a = 0.3001 and b = 6.58 for the longbow (x in millimetres). The unit of force is not stated and there are no R² values or residuals.
An Interactive Haptic System for Experiencing Traditional Archery · Silviu Butnariu, Mihai Duguleană, Raffaello Brondi, Florin Gîrbacia, Cristian Postelnicu, Marcello Carrozzino
-
2019
Context Model Published later
For the yumi, the traditional Japanese bow, a large-deflection model built on a 4.2 kg shihan-yumi finds a three-stage force-draw curve: it rises fast, slows in the middle and climbs again towards the end. It is calculated, not measured, and a reminder that traditional does not mean a single curve shape.
Nonlinear Dynamic Analysis of a Japanese bow (Nonlinear Spring Characteristics and Dynamic Behavior) · Atsumi Ohtsuki, Shigemichi Ohshima
Status history
- 2018 Reported To calibrate a haptic simulator, a group of engineers takes three replica traditional bows, a recurve horse bow, a flatbow and an English longbow, on a dynamometer up to 50 centimetres of draw: the force curves are close to a straight line, with slopes between 0.2498 and 0.3001. It is a test on equipment, so direct for this claim, but a single one, on three light replicas, with no goodness-of-fit index and stopping at 50 centimetres without saying where they are counted from: reported.
Related
Related articles
- The yumi through engineering: materials, asymmetric limbs, draw force and tenouchiHow the Japanese bow works according to the measurements: bamboo and core woods, animal glue, asymmetric limbs, the draw force curve and tenouchi twist.
- 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). On the longbow, the flatbow and the horse bow, draw force rises almost in a straight line up to 50 centimetres of draw (Version 2). In Evidence Registry. Retrieved 16 October 2026, from https://matteocampagna.com/en/registry/equipment/traditional-bows-linear-draw-force
@misc{campagna2026_curvaforzaarchitradizionali,
author = {Campagna, Matteo},
title = {On the longbow, the flatbow and the horse bow, draw force rises almost in a straight line up to 50 centimetres of draw},
year = {2026},
howpublished = {Evidence Registry, matteocampagna.com},
url = {https://matteocampagna.com/en/registry/equipment/traditional-bows-linear-draw-force},
note = {Version 2; accessed 2026-10-16}
}
Follow this claim
RSS is an address you paste into a feed reader: each time this claim changes status, adds a year to its history or is revised, a new item appears there.
Registry updates by email
At most one email a month, sent only when something has changed: claims that change status, new claims, Lab predictions registered or resolved, new studies and new books.
Sign-ups are handled by Systeme.io, the service that runs the newsletter. Every email has a link to unsubscribe with one click.
Other claims in this domain
- CorroboratedAlong its flight the arrow loses an appreciable part of its launch speed12 studiesStatus since 2011
- CorroboratedAs it leaves the bow, the arrow flexes and snakes around the riser instead of leaving straight19 studies · 47 archers measuredStatus since 2012
- ReportedA camera-based scoring system misreads some arrows: the ones barely sticking out and the ones that shift the target face7 studies · 2 archers measuredStatus since 2017
- ReportedA chest band with fibre optic sensors measures breathing and mean heart rate with small errors, and an archer can wear it while shooting2 studiesStatus since 2019
- ReportedA compound bow stores between 70 and 100 joules and sheds about two thirds of the force at full draw4 studiesStatus since 2015