Warbow dimensions (Hey, Jaro and Thimo!)

toxophileken
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toxophileken
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2:39 AM - Dec 03, 2006 #1

Hey Thimo and Jaro, I have been searching for a half hour for the drawing Jaro posted on a couple of Thimo's threads of various warbow cross sections... I thought I added it to my "favorites", but it isn't there...

I am right in the middle of drawing and cutting out the profile on a nice piece of osage...

Could you guys hook me up? I am leaving for church in a few minutes; but if you answer tonight, I will have time to get it laid out tonight in time for tomorrow's meet.

Oh, this particular stave is about 80" long, has a high crown, with great growth rings. I am looking at about 1 1/2" wide, by 1" -1 1/8" thick in the handle area (Looks like that's what is useable). I am going for as much weight as the wood will reasonably give at 30" to the grip. Hoping for 100# or so ("Warbow Lite"). More is fine... And I would consider cutting it to 76" or 74" if that seems better for the draw lenght/draw weight/performance.

Been looking forward to getting to this stave for months, and just now got a bee in my bonnet, I guess...

Thanks very much...

Ken
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Thimosabv
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4:21 AM - Dec 03, 2006 #2

Ken I'll get it in just a bit.
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badger5149
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5:58 AM - Dec 03, 2006 #3

Ken, I doubt if 1 1/8" at 80" could handle even close to 100#. Maybe at 74". At any rate I think you do have enough wood for a heavy bow, Osage is some tough stuff, you wouldnt have any problem getting your draw length even at 72". steve
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toxophileken
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6:13 AM - Dec 03, 2006 #4

You are right, Steve. I believed what you told me the other night... I will probably have to shorten it to get any weight at all... I just was wanting to look at the drawings Jaro posted, and also figure out where to start the taper.

Oh, and in an article Thimo posted a link to the other day, they said they were getting smoother and better performance out of longer bows (like 80", I think)...

Right now, I have drawn a center line down the crown, and lines on each side 3/4" from the center, giving me my 1/ 1/2" maximum width (That is pretty much all there is to work with). I figure I can assess things from there before going to the 1 1/4" you recommended.

I am trying to figure out things about warbow cross section, too. It seems like the cross section I have seen is oval or round... with crown on back and belly. I remember Jaro saying a flat back was ok... I am wondering why a flat belly wouldn't be ok, too.

I guess I have plenty to learn... I hope I can do it quick, before I mess up this primo stave...

"Many counselors bring success"...

No rush, Thimo. I could probably use more time for research and thinking...

Thanks, guys!

Ken
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PaleoAleo
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8:37 AM - Dec 03, 2006 #5

Ken, here's a great way to search PaleoPlanet for past threads:

Copy and paste these words exactly into Google:

"war bow dimensions site 081.ezboard.com "

When searching other topics/subjects, just replace the words "war bow dimensions" with your search terms.

It works great. Hartung showed me how to do this.

Tom
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Thimosabv
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10:58 AM - Dec 03, 2006 #6

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sagitarius boemorum
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7:45 PM - Dec 03, 2006 #7

There is still tapper to tip Thimo, the limbs dont go parallel that long.

Anyway I think that for 100# and osage, 72 -73 is all you need.
I think that longer it will become sluggish.
Osage is not yew, neither is whitewood and attempts to blindly follow yew bow shape and dimension does not make it out.

Jaro
32 down on the Robert McKenzie
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toxophileken
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7:35 AM - Dec 04, 2006 #8

Thanks guys!

Wow, Tom, I think I am more excited about the search method than the warbow dimensions, now...! "Feed a man to fish/ Teach a man to fish... etc etc." Thank Hartung, too, please...

Thimo, thanks for sending that diagram. I had actually found that one, though... I am looking for the drawings Jaro made and posted at least twice (once on one of your threads). It had cross sections and dimensions of some MR bows...

Jaro, I found a written description that you had posted to someone, and then remembered I had copied it into a Word document on my hard drive so I could use it later without having to look for it. Irony... Yay. I had to convert the centimeters to inches... You know, only scientists use the metric system here... Ha ha.

Here it is:

"Matt, when making a let say typicall run of the mill Marry Rose warbow then -

The handle is offset 3 cm up and 7 cm down from the median line (middle of the bow).

The width will be say 35 mm. Now 10 cm up and down from handle the width will be the same.
Then the tapper goes to the tips, but as if the tips were about 22 mm wide.
15 cm to the tips, the taper goes abruptly to the 12,7 mm (1/2).

This last taper is clearly visible.

Thickness tapper in comparition is rather straight, without any raised handle.

Jaro"

I can't seem to paste much more than half a sentence or so into the PP quotes, bold, or underline right now... At least my computer is back to working, though... (wasn't this morning).

Jaro, I didn't see a length in there...?

Actually, 100# is not the goal... AT LEAST 100# is the hope. The goal is the most the wood will reasonably give... I guess I will proceed with what I have (1 1/2" wide, by maybe a bit over an inch thick) and see what I can get.

I appreciate the comments on length you made... I am wondering how long it should be at various weights at my draw length (30" to grip). I realize that I will have to get the outer limb pretty thin and light to avoid handshock and sluggish performance. I am thinking about tip overlays, so I can get really thin tips.

Steve made the suggestion that I get the handle to width, put a long string on and pull it with a scale until the handle starts to bend... If I understood him right, that would tell me what the max weight for that stave would be (for that length). Of course, I don't have a scale that goes over 100# (there must be a way to use two in tandem, somehow...).

One more thing... I saw in an article that Thimo posted that they are seeing better performance and comfort of shooting with longer bows (80" or more, I think I saw)... Jaro, any thoughts on that, too?

Thanks so much for your help, guys. I hope my computer hangs in there until I can read whatever you reply. I have a sercive call for the cable tomorrow... Hope it is that and not the computer itself...

Ken
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badger5149
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8:52 AM - Dec 04, 2006 #9

Ken, I measured the thickness on a 100# at 32' bow, it is 74" long and 1" thick, 1 1/4 wide 74" long and made from hornbeam, I would think at 1 1/8 with osage you might make it afterall. Worth a shot anyway. I just went and measured an osage that is 72" long drawing 85# at 30" and bends in the handle it is 1.1" thick. Hard to say. Steve
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sagitarius boemorum
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12:04 PM - Dec 04, 2006 #10

Ken I went all through the MR electronic archive and

5 is under 190 cm
28 from 190-195 cm
35 from 195-200 cm
29 from 200-206 cm


Making the bow as long as 80 is actually one of longest. Reasons to make it so long is favorable string angle when dealing with a bow of say 150#.

If you make just 100#, 72-73is all you need.
Also see that lots of MR bows is shorter than we make todays replica.
You also need relativelly small ammount of wood to hit the weight.

Jaro
32 down on the Robert McKenzie
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Thimosabv
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1:12 PM - Dec 04, 2006 #11

Awsome info Jaro.


Ken I have the cross-sections as well. I have the book now that has the photo. I can either scan it in, or find the one Jaro sent me. Either way let me wake up 1st.

PP and coffee the ultimate morning refreshment.
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Juri
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1:30 PM - Dec 04, 2006 #12

Jaro, what would you recommend for length to a 80# at 32" bow?
I dont believe I can draw 100# yet.
I have a good, straight 80" white ash stave. A test piece (dry) sunk in the water 74%.
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Thimosabv
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1:33 PM - Dec 04, 2006 #13

Here is a scan of what I have. I'll check over my files for more.


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Thimosabv
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1:37 PM - Dec 04, 2006 #14

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Thimosabv
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1:44 PM - Dec 04, 2006 #15

The Mary Rose bows
The Mary Rose, an English war ship, sank in the English Channel in 1545. A marine archaeology team recovered the wreck in 1978. Among the artifacts were a large number of yew longbows. W.F. Paterson gave a few of the dimensions of some of them in the "Journal of the Society of Archer Antiquaries".




Various Mary Rose bows



Bow ID #
Length,
inches (cm)
Center thickness X width,
inches (cm)
Other Details
A807 71.7 (182) 1.25 X 1.5 (32 X 3 "squarish"
A812 70 (17 1375 X 1.5 (35 X 3 D shaped
A855 77.25 (196) 1.375 X 1.375 (35 X 35) circular
typical 78 (19 1.25 X 15 (32X3 elliptical
typical 75 (191) 1.5 X 1.5 (38 X 3 elliptical, 11 inches from center 1.25 X 1.5



Bob Kooi, a scientist from the Netherlands who has done extensive modeling of bows ancient and modern, supplied detailed information on a particular Mary Rose bow. The data was in the form of cross-sectional moment of inertia instead of width, thickness and cross-sectional shape. That's completely sufficient because in order to compute the draw weight you must convert the cross-sectional data into moment of inertia. Kooi's data is summarized in the following table assuming that the cross-section is elliptical and the thickness is 80 % of the width:




Mary Rose dimensions from Kooi's data



Distance from center,
inches (cm)
Width,
inches (cm)
Thickness,
inches (cm)
0 (0) 1.32 (3.35) 1.65 (4.19)
8.7 (22.1) 1.21 (3.07) 1.51 (3.84)
1657 (44.2) 1.11 (2.82) 1.39 (3.53)
24.5 (66.3) 1.00 (2.54) 1.25 (3.1
32.3 (88.4) 0.83 (2.11) 1.04 (2.64)
38.23 (110.5) 0.46 (1.17) 0.58 (1.47) tips



The Mary Rose bows have dimensions very similar to tzi's. Does that mean that he, like the military archers of Henry VIII's England, shot a very powerful bow quite often or was tzi's alleged weapon really an unfinished stave?
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sagitarius boemorum
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2:46 PM - Dec 04, 2006 #16

Juri 185 cm is all you need if it is good ash.

Jaro
32 down on the Robert McKenzie
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Juri
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8:10 PM - Dec 04, 2006 #17

Wow, thats amazing! Thanks a lot Jaro!
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toxophileken
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1:37 AM - Dec 05, 2006 #18

Thanks again, Steve, Thimo, and Jaro! I really appreciate it.

Very good info, Steve. I guess I will start at 1 1/2" and work it down to 1 1/4" or 1 1/8", get the taper, and see how much I might need to shorten it. 76" is sounding doable, maybe...

Thimo, I hadn't seen those photographs, or all the numbers. I will have to rally concentrate on the numbers to get anything of them... "Dammit Jim, I'm a photographer, not a mathmetician!" Ha ha. Useful stuff, seriously, though.

I guess with all this, I don't need the sketches I was orignially looking for. I think they are by Jaro himself. They had drawings and handwritten notes....

Jaro, very usefull info. Better to have too long a stave, I guess... I just don't want to cut it short and wish it could be longer again... Ha ha. I am trying to figure out if I want to make it symmetrical, or offest in the handle as you mentioned in the quote to Matt (above).

Juri, good luck!

Ken
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toxophileken
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9:20 AM - Dec 05, 2006 #19

Ok, another question or two...

Jaro, is it necessary to crown the belly? I mean, if it is still narrow and deep (5/8 rule, or whatever), would there be a disadvantage or advantage to making the belly flat, rather than round?

One more - Do you have to have horn nocks to call it an elb?

And, if it pulls 120# or whatever the minumum for a warbow is, but only casts the war arrow 75 yards or so... Would it still be considered a warbow, or just an exercise machine or crow bar or club...?

Ken
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sagitarius boemorum
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1:57 PM - Dec 05, 2006 #20

If it is quadratic in profile, then there is too much wood on it. Rounding allows you to remove lots of wood , but to have practically the same stiffness of beam.

I think that if you use 52 gram standart arrow as a benchmark

80# shall shoot it around 200 yrds
100# 220 yrds
120# 240 yrds
130# 260 yrds

Also, it looks like there is a threshold on around 125#, past which not much gain in distance is achieved, unless the bow is made from really good wood and pampered.
Heavier but allows using heavier arrow.

Armour piercing arrows starts around 3 oz.

Jaro
32 down on the Robert McKenzie
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