Yanghai (Scythian) bow drawn pictures

[Adam Karpowicz]

Taking advantage of higher humidity in the shop, I finally got around to draw the bow on the scale to show the movement of the limbs during the draw. Please have a look - on one of the pics the reading of the scale can be seen above the bow - 110lb at about 1/2 inch short of the proper AMO 28 inches. (AMO 28in draw = 26.25in from the belly of the grip). The real 28 inches draw will be several pounds more than AMO, since the grip is 1 inch thick, not 1.75in. Anyway, the bow is 115-120lb at 28in.

Note most of the bending takes place at the centre 2/3 of the bow - at the grip and at the deflexed portions of limbs. The outer limbs flex very little. However, the bow was made according to the drawing by Stephen, where the thicknesses of the outer limbs were not given. I took the photos of the origimal as the guide for that and assumed there is an even taper down from past the deflexed sections toward the tips. I have no doubts the original bows could have the outer limbs thinner, or thicker, so the flexing of the limbs there would vary from bow to bow. The incresed flexing in the outer limbs would reduce the stresses, but not necessarily make the bows more efficient and may cause more stacking for lesser energy storage.

In making this bow, I aimed to find as much as possible about the manufacturing process and to determine the final draw weight, not to test for performance. This can be done better once more such bows are reproduced, since the bending of limbs, the overall shape and the exact thickness/width of limbs will vary, which is obvious from the pictures of the originals. I shot the bow part-drawn a few times and it seems quite fast, even with the string follow etc., and there is very little hand shock.

Here is a short movie of the bow on the scale: http://s806.photobucket.com/albums/yy34 ... idrawn.flv

Adam

[Adam Karpowicz]

another picture:

[Jos?Dom]

Adam, it looks great. Congratulations.

[daryush]

Wow, that looks fantastic! Congrats on successfully making it!

[Alan Flashing]

Very nice indeed Adam, look forward to your further work on this design.
Alan

[Kviljo]

Outstanding!! I hope you are planning on writing down what you learned from making it. (We'll buy the book )

And what a good looking bow!

Do you have any thoughts on how far these were drawn? - I'm thinking of the extra little bit of potential unrolling of the recurves. Could they be unrolled completely, or perhaps the massive recurving and nock configuration would make the tips unsafe if they were unrolled fully?

[Adam Karpowicz]

Thanks for the comments.

Ivar, the tips do not "unroll" in these bows, because the tips, together with the outer limbs are near-rigid, so they are nothing like the modern recurve. The string lifts-off the reflexed ends providing a little extra energy, but not much. The arrows found with the bows were up to 32 inched long.

Adam

[Kviljo]

Ops, my bad - I ment that the string perhaps could be lifting off the recurve all the way to the nock without having trouble with stability or string centering in the groove? But at 32" I guess it would unroll the string or lift off all the way? Otherwise it would seem like the design had a bit of unused mass at the very end of the tips?

(Again, what a cool bow! )

[Bede]

Adam,
The shape of the bow looks very much like some of the bows in the Greek vase paintings. The brace height also looks like some depictions and seems to conform to the shapes of the gorytos plates (they are quite wide) for the shorter form of this bow sometimes used in the West.


There other forms of the bow depicted with smaller brace heights. They look more stretched out. Perhaps the performance of these bows would be slightly different.

[jack farrell]

Such a beautiful bow!

Does the outer wrapping go down into the string groove and continue around? Or did you have to cut the sinew skin?

How far does the sinew backing follow through the inside curve of the tip?

[ravenbows]

Adam,

Very impressive work...........do you have any plans of shooting the bow at full draw?

[jbl]

Wow. One word incredible.

[Adam Karpowicz]

Thanks everyone for the comments. Yes, this bow was a challenge...

As to the performance. I think we should not split hairs over that. The other originals show different recurvature at the outer limb and some seem to have just a short hook at the very end. It may mean the old bows straighten-out in the graves, but I doubt it, since clearly the limbs are made on the base of the ibex horns. The horns would not straighten much inside the limb spontaneously without some pressure, so it is reasonable to expect the curve to stay close to original. And each pair of horns had to have a different shape as well.

I believe the "lift-off" effect was not counted on in this bows and the bowyers paid little attention to it. Possibly as a side effect in some of the bows this was taking place, but if the archer actually noticed anything it is another matter. Yes, the string would clear the tips almost completely on this bow when drawn to 32 inches, but this would happen easily on many other such bows at a much shorter draw.

This is ane of the reasons why I feel no urgency to test the bow, since the performance will vary quite a bit from bow to bow. We need more such bows to have something more to work with.

Jack, the sinew backing and the wrap goes all the way to the bits of horn sticking out at the ends, but the sinew is cut through in the groove except maybe for an inch where the groove starts at the outer limb. I am very curious how your bow turns out, so we can compare them both.

Adam

[scemdonmez]

Congratulations Adam, how long is the drying period?
İs it stable bow?

Cem

[Dusan]

Adam- "bardzo pienkny -niesamovity " -congratulation !