Saturday, February 25, 2012

Fresh & Incomparable New Bow Backing Method-Golhan Methods

Synthetic Ottoman Bow/Stingray Covered /Golhan Bow


Hello,
I would like to mention about my new methods, tests and try-outs as I promise before.
Bow and arrow combine is one of the most deadly weapon of the history. That was generally priciple weapon of almost whole nation.
The main and simple idea was stop the opponent in a best possible far distance where he can not harm. Through this main aim, the bow was always in a progress period, especially for steppe warriors, for achieving better range and effiency. And when these kinds of goals achieved, were assumed as a military secret. These secrets, which were not written to a manual etc., were tried to keep between the master bowyer and apprentice for hundreds of years, especially in eastern nations, same as Ottoman master bowyers.
My story was similar. I asked to myself several times that how can I make my bows faster, how can I use the additional weights on the bow for efficiency.
It is supposed to be known that, the purposes and effects of the horn & sinew on an organic-composite bow. But there is generally something omitted. The cover on the sinew, leather!
Furthermore, there was almost an "obsession" of the Ottoman bowyers for this issue, Horse Leather! Why horse leather, not sheep, not goat, why especially rump leather of horse.
At the begining I could not understand the main object and asking same questions above.
But one day there was idea arised about this; Is it possible to use horse leather with the same purpose of sinew? Can the leather act as or like sinew? If so, was the horse leather best for this goal and was it kept secret?
After these question salvos, I thought, why not, I should try this! And I started to test 0,8mm goat leather through this point of view.
1) Leather Test: I determined the resistance, flexing and tear capacity-limits of a piece of goat leather which was fixed to a static clamp. At the end, I saw it may act as the same way of sinew and add a some draw weight to the bow!
Moreover, I saw these additional effects were depented and could be increased with the thickness, type-kind of the leather also the organic or synthetic varnish materials as well.
I used spirit (kind of grain alcohol) and an organic shellac solution and saw great positive effects.

2) Determining the stretch amount of the back portion of a synthetic bow: I measured the stretching capacity of the back when the bow unstringed to the maximum draw lenght with a flexible tailor's ruler. The difference was 5-6mm. The sinew portion is stored its power in this 5-6mm! Through this, i can achieve this with leather while forcing the leather work between or similar range as the sinew.
At the end of these tests, I decided to the backing process and method of my synthetic bows. I called the process "stiffing the leather" (by stretching the leather to its limits before backing) and called the method as "pre-tensioning of the leather"
I also configurated 5 different ways for appliying this technic for both sythetic and organic bows;
1) On sythetic bows, pre-tensioning the leather before backing and applying leather while the bow unstringed.

2) On sythetic bows, pre-tensioning the leather before backing and applying leather while the bow unstringed and applying some force to closing of the bow tips and finally,tying the bow from it's tips.


3) On organic bows, after the tillering adjustment process, force to stay beyond unstringed position through holding and tying the bow from it's tips and making the backing while the bow fixed in this position with pre-tensioning of the leather.
4) After streching the leather between clamps to its limits and fixing the leather in this position with organic or chemical solutions.

5) Using same method as on above method but with holding the leather in water and streching it with clamps or rollers for a some drying time.
That is it…
After I realized that, those methods and/or point of view is not written on famous books as Bowyer's Bible series, Ottoman Turkish Bows/ Adam Karpowicz,etc. I assumed the archery community is not aware or do not appropriate importance to the effects of leather on bow backing and wanted to share my opinions and search-try out results with you… I hope these  technics called "Gölhan method" together :-)
My next goal is to cover a sythetic bow with horse leather through the methods those I explained above and testing the efficiency-draw weight effects of the leather.
Please stand-by :-)
Mehmet Gölhan / Bowyer