#49
Post
by yeoman » Sun Mar 09, 2014 7:09 pm
I am sorry to come to this conversation late.
A few points which do not necessarily add either way to the original thesis, but nevertheless I think would be important to be aware of:
Of thin tipped bows on the Mary Rose:
I would be most resistant to believe that the bows on MR had thin tips in order to recurve them. This is for a few reasons:
- It is better to recurve the tips of a bow when the tips are wide, as this allows the bowyer to minimise twist in the tip, and leaves material to account for it if it does happen. I think even glass/carbon bowyers of today do this.
- These bows were weapons of war loaded onto a warship going to war. Just because the bows had tool marks left in them does not mean they were unfinished and/or meant to have further work done on them at the end of their journey. These weapons would have been efficient without having 320 grit sandpaper
Of recurved longbows:
Firstly, if it has recurved tips it is not a longbow...it is a recurve.
The point of a recurve is to provide beneficial mechanical advantage in a bow of such length compared to its draw length to allow for a fatter F/D curve that would otherwise experience stack in the draw. Ensuring a recurve remains recurved means adding wood to resist bending. This adds mass. This is not so great an issue on short bows because the mass, relatively, is all closer to the handle than on a longbow. On a longbow of sufficient length compared to its draw, there will be no stack unless it is tillered exceptionally poorly, and the F/D curve will have a nice plump shape at the bottom. Adding recurves for the sake of a few extra stored joules will be nullified by the extra mass that energy will have to accelerate.
If the tips of the MR bows had been recurved (or at least were intended to be recurved), then the resultant recurve would have nearly all pulled out early on, because there would not have been enough wood to support the load.
Of Yew and lightness
It is not the lightness of Yew that makes it a good wood. It is not even its stiffness, as its stiffness is very low. The reason Yew is such a star performer is because of its elasticity and its capacity to withstand strain. Good spotted gum might have a working strain in a bow of 0.75%. Very good spotted gum might have 0.82%. Yew regularly tests around the 1% range. A few pieces of exceptional Ash and Osage might also have such extraordinary numbers.
What does this mean? Well, the higher the working strain of a wood, the thicker it can be to achieve a given stress. As we know, stiffness increases with the third power of thickness. If you can find a wood that can take more strain, you can make the bow narrower and thicker. This means less mass, and logistically it means more staves out of a given diameter tree.
Of illustrations
I think it is perfectly reasonable to accept one image that supports a hypothesis and reject another that refutes it. Within reason.
Extant images must be treated in just the same way as extant texts. They must be analysed and assessed for creative bias, intended purpose and also the context of its creation and audience. We know the images of St. Sebastian are all terribly anachronistic. The people at the time probably knew. But they knew the artist was representing not just an event but a concept. It's quite a complex subject and probably best thrashed out elsewhere.
There are a few images in Hardy's Warbow where all the archers are shooting bows in which the lower limb is nearly straight and the upper limb has a slight hinge halfway up the top limb. Will this change how I tiller my bows? No. Do I understand how hard it is to draw/paint an even tiller? Yes. I'm sure there are a myriad of reasons the bows were drawn this way. I need not jump to the conclusion that the image must be representative of the material culture.
Aside from bows I also do historical martial arts. I have spent untold hours poring over images and translating arcane and obscure mittelhochdeutche. Some images I am happy to accept when they support my hypotheses, and am equally happy to reject others when they refute my hypotheses. But it is not because they refute or support my hypotheses that I accept or reject them.
On recurved bows
I think there are some clear cases where illustrations in medieval and renaissance art intended to show recurve bows and that the illustrators sought to represent real material culture. These bows often come from southern Italy and Spain.
I think there were recurve bows in medieval and renaissance times in Europe. Do I have hard evidence? No, not really. Does that mean there is no evidence? No idea. There might be some artefacts hidden somewhere. I hope there is.
I do not think there was a need to recurve the ends of English Warbows. I think this because of extensive personal experience making bows and studying engineering to make the best bows I can. Our toxophile ancestors (toxophilic ancestors?) did not have excel spreadsheets, but scores, nay hundreds, of generations of bowyers before them who passed on their hard-earned knowledge.