ILAA - Definition of the Longbow

longbow Definition of the I.L.A.A.

A full and detailed engineering definition of the longbow is what keeps the sport safe. This definition takes account of and includes all forms of the longbow from the heavy-weight Artillery / Livery bows to the lightest target bows; from full compass bows to limb-flexed bows; from horn-nocked to self nocked; from bows with or without handgrip; from laminated to self-bows.

The International Longbow Archers Association longbow definition (© Mr. R. E. Cornhill)

Input for this definition was gathered from around 100 bowyers, archers, related experts and engineers.
It was widely consulted and then codified by Mr. R. E. Cornhill who is a materials engineer.

The aim of producing Rules for the Definition of the longbow

To separate technically and ascetically the longbow from all other bow types from around the world.

To provide a level playing field for the development and manufacture of high performance bows for target, distance and all competitive shooting.

To provide rules that bows can be checked to simply in the field with simple tools.

Rules to define the required compliance of a longbow

Materials

Bow construction and form

CF1. A maximum 6 laminates of type any wood types, placed in any position in the bow may be used. Any repair or handle build-up will be counted as a laminate.

CF2. The finished bow can take on a side profile shape with any of the following features i.e. Any amount of string follow.
Any amount of forward limb set and any amount of reflex
Any amount of rec-curve as long as the curve starts not less than half way along the limb when measured from the nock point.

For all the above, when the bow is strung the string must not touch any part of the bow other than where the string is nocked.

CF3. Viewing the bow by looking onto the back surface, the bow will taper from its maximum width at centre down to the tips.
Any taper profile is acceptable and the centre section may be parallel.There must be no reduction of width in the handle area, the width at the bow centre must not be exceeded at any other position along the bow length.

CF4. The cross-section of the bow at any point along its length can be of any size and shape ie. round, oval, “D” shaped, square, rectangular etc. as long as it fits within a rectangular template with a ratio of sides 1 to .625. Where the front and back surfaces of the section must touch the long sides of the template. See examples below.

Examples

Examples of any cross-section shape fitting into a 1 to .625 ratio rectangular template, with the sectional shape touching both long sides of the template.

CF5. The handle may be built up on the belly side with wood to form a comfortable hand grip, more necessary with light draw weight bows. No arrow rest ledge of any form is allowed.

CF6. Horn string nocks may be used. These usually take the form of a slim conical shape bored out from the cone base to fit over the bow tip. The string can also be retained with nock grooves cut into the bow stave. The grooves can be of any size, shape and form.Horn and self nocked bows can also incorporate extra grooves to fit a slack string, to aid stringing the bow.

CF7. There must be no artificial aids to aiming and sighting, either on the bow or the string. Rubber bands, tape or sight marks of any kind are not allowed.

Note: The above freedom of form and cross-sectional shape allows most types of longbow to conform to the rules. Typically replica late medieval hunting and war bows. Victorian target and sporting as well as modern target, clout, mark, field and distance shooting bows shall all comply with the rules that define a long bow. Any existing longbows used in the above catagories will almost certainly be compliant.

Reasoning for the rules

M1. Mostly for traditional reasons, but impregnated laminates would give an advantage to a user who could afford the cost of creating a high tech. composite more akin to glass and carbon fibre composites.

M2. Not an essential rule, but some such bows do already exist and are at present legal. Bamboo has a very high tensile strength, higher than any wood and is low mass for its strength. Its advantages are particularly accute in distance shooting. It is therefore in the tradition of flight/distance shooting that the concession cannot be applied as its advantages over other bows would give an unfair result.

M3 & CF5. Maintains the status-quo of existing rules.
NOTE. Only horn nocks are allowed by the BLBS for target shooting bows.

(apparently based on Victorian tradition ).

M4. To preserve and lengthen the life of a bow.

M5. Leather is the usual wrap material for a bow. No material gives an advantage except to possibly afford a better grip.

M6. One would presume the best adhesives would be used which for reasons of safety and bow longevity is in everyone’s interest. It would be difficult or impossible to test what glues had been used. Best to not have rules that cannot be enforced.

M7. This allows any personal preferences, but does not allow non-wood to be disguised and hidden.

M8. Non natural wood can and will be used to give an arrow speed advantage, as used on flat-bows. It would be difficult or impossible to write rules to control materials, patch size and thickness, patch position etc.

CF1. Gives freedom to experiment and develop with woods and combinations of woods. To help save costs, as by laminating non perfect ( knots, flaws etc ) staves, imperfections can be offset and misaligned to still produce good usable bows. I cannot see any reason to over specify that restricts in any way.

CF2. Possibly the most contentious of rules. Apart from the technical difficulty of writing controlling rules there is the difficulty of checking. When closely examining some of the reasoning, does it matter. Re-curved tips seem to be the most argued point, but as long as the string does not touch the bow at any other point than that where it is nocked it offers limited advantage, and some disadvantage.
The re-curve tips give less bending, therefore the rest of the bow has to bend more and wood has bending limits. Therefore a bow of the same draw length and draw weight would have to be made longer. A longer bow gives higher inertia, that slows the bow tips and therefore slows arrow speed.

If the re-curve starts as a minimum of halfway down the bow limb, the side profile would look ascetically acceptable, not the buffer low horn look of south European or Asian bow.
The same applies to re-flexing the whole bow, due to the limits of wood bending only limited re-flex can be built in without over stressing the wood or making the bow longer with its limitations.
The less rules, the less detailed measurement and examination needs to be carried out, with the ensuing grey areas and argument.

CF3. The front and side tapers of a bow dictate the tiller shape, which has to be within limits, or the bow will permanently distort or break. Therefore the tapers are self controlling. From the front view, any width narrowing in the handle area brings the bow into the flat bow type.

( it does not look like a longbow ).

CF4. Probably the second most argued about rule, but under close analysis need not be.

First if the bow section fits within the 1 to 0.625 ratio rectangular template it is not a flat bow, any wider or thinner would be.
Secondly because wood has its bending limits, this section ratio dictates the bows minimum length for a given draw length and draw weight. For bows of short draw length and light draw weight as needed by some older archers and slight lady archers a minimum length could be over restrictive and not allow them to compete in some disciplines at all. Wheelchair bound archers could not physically shoot any thing but short bows.

Considering the actual shape, the flatter the maximum tension and compression surfaces are the lower the stresses will be all other things being equal. Higher stresses cause permanent distortion or breakage, therefore any assistance to design lower stressed bows should be good.

The much argued for traditional Victorian “D” section is technically a poor design which gives unnecessary high local compressive stresses, causing string follow after little use, unless the bow is made over long.

CF5. A built-up handle can give a more comfortable grip that can help accuracy. This feature is allowed at present, therefore many such bows exist. Which would became illegal if a built-up handle was not allowed.

CF6. All as the old rules allow. Some of the high draw weight bows would be almost impossible to string without a slack string stringer and its attachments.

CF7. Self explanatory. (more of a shooting rule than the definition of a longbow).