For an understanding of asymmetrical bow- designs I should add another thought of Michael Winkler, comparing the string of a bow to a string of a musical instrument. The point of the lowest vibration of a string is determined by the Golden Ratio. So a nocking point adjusted according to the Golden Ratio guarantees an optimum transfer of the energy stored in the drawn bow.
Choosing bow- staves for asymmetrical bows I had to realize that trees or brushes are growing more or less according to the Golden Ratio. Look at a tree and you´ll realize that branches are arranged in matching the Golden Ratio. Maybe I´m wrong, but I´ve found a lot of staves grown like that:
The lower shorter limb is the lower thicker part of the branch, at the handle there was a crotch, so I had to cut of another branch, the root of the cut- off is still to be seen. I worked this bow leaving it its natural growing as far as possible. It is always a good idea to locate the handle at a crotch cause there is no bending.
With its humb in the upper longer limb this bow looks very rude, but somehow very stylish, its a beauty by nature.
As usual hawthorn- bows are strong, cause of the staves´”snaky” growing, I had in mind to do a good tiller job first, but finally I made a 57lbs at 26″ bow, it is a real fast bow.
The upper limb of an asymmetrical bow is longer and so it weighs more than the lower limb. When you´re used to shot a bow with a so- called loose grip you´ll benefit of an asymmetrical bow.
An asymmetrical bow tilts forward just after the release when shooting it with a loose grip( the bow is “clamped” by the index and the thumb). This is exactly what you´ve to learn in kyudo:
Wow, this guy is shooting just more relaxed than me. I appreciate his body alignment very much, he knows how to release with both feet on the ground!
It´s quite interesting to look out for asymmetrical bow designs outside of Asia. Among the Native Americans the Hidatsa- tribe is actually retaining a slightly asymmetrical design, maybe this is another proof for the Native Americans having migrated via the Bering Strait, the Hidatsa asymmetrical bow- design has been researched by the University of North Dakota. The historians found out that the ballistic trajectory of an arrow shot by an asymmetrical bow is more flat, this researching result is matching researchings of some Japanese Universities focused on yumi- bows. So it should be easier to hit the mark with an asymmetrical bow.
That´s a f/d curve of an asymmetrical bow: the curve is an exact copy of the draw of the bow. At the beginning of the draw you´ve to move both limbs, the curve is steeper, so the early draw is feeling stronger. The curve continues more flat before ending up a bit steeper. A f/d curve of a symmetrical longbow is much more constant. No humb! The space under the curve is the energy- storage of a bow, if there is a humb energy- storage is usual higher.
Asymmetrical bows are storing up to 115% of energy, but efficiency is anyway low. I´ve to check out this inadequacy.
The Canadian bowyer Patrick Menzies is assuming that asymmetrical selfbows have to be made very strong for to take full advantage of this design.
An asymmetrical bow- design is a great option for to take advantage of branches of hawthorn, blackthorn, spindlewood and alike woods.
Next volume is focused on samples of asymmetrical bows.