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Arrow speed

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So just for fun I am trying to marry a concept of a traditional horsebow with 400+fps speeds. This site has some extremely impressive data using Turkish horn flightbows upwards of 100lb draw

https://atarn.org/islamic/akarpowicz/turkish_bow_tests.htm

So that's pretty impressive considering one of the top of the line state of the art crossbows as of 2021, the Ravin500 only pushes past 500fps.

Turk horsebows are good, but what about the original hornbow, the asymmetrical Scythian bow?

https://www.tapatalk.com/groups/paleoplanet69529/old-designs-reloaded-asymmetrical-bows-t23054.html

This is a fanciful musing about bow harmonics and asymmetry from a traditional bowyer followed by some interesting data and discussion.

Here are my thoughts. A down/swipe khatra rather than a torque/side khatra when used as the Saracen archers were described as doing, will put even more kinetic energy into the arrow especially if the archer has the musculature. Torque khatra is just not going to put nearly as much kinetic energy into the shot as a down or swiping sort of "punching" khatra due to the mechanics of the human body.

The tests done with the Turkish hornbows were done with a machine that did not emulate khatra. And still produced a whopping 357.1fps with a 203 grain arrow out of a 44" 125lb pull Turkish flightbow made from horn.

So with swipe khatra, light arrows and proper musculature these hornbows maybe could come close to 400fps.

Here is a video demonstrating proof of concept of khatra increasing arrow fps;

https://youtu.be/zKH3lzIJ5v8

A small point of concern for me is, with this technique it may be best to have a bow with the lower limb short enough that it will at most reach to your armpit when shooting square to the target. Otherwise you cannot really push the bow with as far down an angle because the lower limb has to be angled around your body if it is longer than this measurement. I suspect but it is definitely untested, that having to angle the lower limb behind you when casting the bow via khatra like one would cast a fishing rod. Just like fishing, if the pole handle is so long that it is stopped during the cast because your body gets in the way, obviously you can't cut a larger radius of swipe. So your force leverage is decreased I think. I don't know, I am not a mathematician or physicist.

The other hypothetical concerns the asymmetry. Two notable examples are the archaeological Scythian hornbow and the Kyudo longbow. A third detail is the 'falcon grip' technique in Arabic archery. The concept here, which seems to cross cultural and time boundaries is that there is a use for bow asymmetry, specifically the upper limb being stronger than the lower limb.

To the archer used to symmetrical bows who does not use khatra, or maybe does but only uses torque khatra this may seem to be a primitive design flaw. The Scythians cannot really speak on this because of timelost secrets but the Japanese certainly can and have justification for the asymmetrical bow used in Kyudo. Their justifications though, I do not think would be the same as those made by the Scythians. The Japanese say it is to make drawing easier without much loss of power. Plus they use torque khatra. I do not think the Scythians were doing torque khatra, though that is a huge baseless assumption.

My thought, though it may be mistaken, is a simpler take than the fanciful notions of Golden Ratio harmonics and other "astrology" musings, or easing the draw of the bow.

I think it's simply about capitalizing on the kinetic energy of khatra. With swiping khatra, most of the kinetic energy of khatra is going into the upper limb. So why not make it significantly stronger? Makes sense. Symmetry however, does not make as much sense when using khatra. The force on the limbs is totally uneven, with a great deal of push being thrown into the shot by the archer into the upper limb, while the lower limb is pulled toward the archer by a weaker force.

I have more thoughts on this but this post is already getting very long. If any bowyer's are reading this please do speak up, I'd love to design a bow based on these concepts as a community!

I thought about keeping these thoughts to myself and constructing a Scythian style hornbow for either a proof of concept or to just discard a disproven idea, but that will take time, I am not a bowyer or a 'professional' horsebow archer. Life comes at you fast and I do not want such an idea to be lost in the event I simply forget about it.

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