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Ben P.




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PostPosted: Fri 30 Jan, 2009 9:34 am    Post subject: Crossbows effective versus Plate?         Reply with quote

I'm thinking Western Europe from 1330-1690 (With a draw weight around 400-600 pounds) Also how effective where they against Lamellar and a Lorica Laminata?
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James R.Fox




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PostPosted: Fri 30 Jan, 2009 9:46 am    Post subject:         Reply with quote

Sir-In that period the rachet steel scossbow (they had spring steel then) went up to 1000lb draw weight. They could smash plate, let alone mail or scale.
Ja68ms
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Ben P.




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PostPosted: Fri 30 Jan, 2009 10:14 am    Post subject:         Reply with quote

Thank you Happy , so they could smash plate but could they get through?
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Ben C.





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PostPosted: Fri 30 Jan, 2009 10:30 am    Post subject:         Reply with quote

http://www.myArmoury.com/talk/viewtopic.php?t=6838

this thread contains considerable debate about the power of crossbows and their effectiveness against plate. There doesn't seem to be a lot of evidence, either from damage to historical items, eyewitness accounts or modern recreations using fairly accurate items/conditions, that crossbows used on the battlefield penetrated plate harness. I have little information as to how lamellar or scale armour may may perform as modern testing tends to focus mostly on just plate with a little bit of mail and cloth testing on the side.
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Leo Todeschini
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PostPosted: Fri 30 Jan, 2009 11:28 am    Post subject:         Reply with quote

With luck in about a month I should have a 250lb, a 350lb, a 450 lb and a 700lb all together at the same time and I will try to run some tests.

Tod

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Gary Teuscher





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PostPosted: Fri 30 Jan, 2009 12:11 pm    Post subject:         Reply with quote

I'd be extremey interested in this, Leo!

On the draw lengths, will you be using the 4-5 inch powerstroke or something more along the lines of a 6-7"? I feel this would have a major impact on the tests.

Just wanted to mention, a lot of your info has been very valuable on some issues regarding crossbows and other bow that I have been researching.
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Randall Moffett




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PostPosted: Fri 30 Jan, 2009 1:29 pm    Post subject:         Reply with quote

Tod,

Wow I am very interested... Make sure to record it so we can watch! I know I'd love to see.

RPM
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Leo Todeschini
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PostPosted: Sun 01 Feb, 2009 1:55 am    Post subject:         Reply with quote

Hi Randall,

Come on up, you are only an hour and a half away and it is a way to kill a Saturday morning.

Can you PM your number to me and I will let you know if I get my act together.

The 250 and 350 and 450 are about 5.25" to 5.5" . The 700lb is not yet made but the prodd will be a bit short on the draw and I would want about 6.5", but it is likely to be about 6"

If we did this we could ask Glennan down with a big bow for a bit of variety, maybe even get Kevin at Plessis Armouries who is pretty local to here to provide some medium carbon plate or am I getting carried away?

Tod

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Ben C.





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PostPosted: Sun 01 Feb, 2009 2:23 am    Post subject:         Reply with quote

Thank you very much for doing this. It's always great to see people willing to do these kinds of tests as they really help our understanding but there haven't been enough of them over the years. I think everyone would be very appreciative if you could record of video of your testing session.

What type of armour do you plan to test against? It would be nice to see a wide range of accurate armour types used but of course that's really asking too much financially. I'm especially interested in how multi-layered gambesons stand up because it has seemed that a lot of people have heavily over-looked the protective abilities of textile armours, both as stand-alone defence and in combination with metal ones.
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Randall Moffett




Location: Northern Utah
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PostPosted: Mon 02 Feb, 2009 6:54 am    Post subject:         Reply with quote

Tod,

PM sent.

I'd love to come up and help out. I will call Glennan today sometime and see what he is up to. If Kevin would be willing that would be great. I might be able to make some textile armour squares perhaps but I'd need to see where I was work wise as I am nearly buried to my neck in thesis at the moment.

Maybe we could do some distance shooting as well.

I bet we could take up a great deal of a saturday with such things about.

RPM
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Glennan Carnie




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PostPosted: Mon 02 Feb, 2009 7:49 am    Post subject:         Reply with quote

Randall, Tod:

Yeah, I'm up for that. I'll bring a bow along for comparison (if it's not so cold I can't draw it!)
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Gary Teuscher





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PostPosted: Mon 02 Feb, 2009 9:16 am    Post subject:         Reply with quote

I'd be curious as to what weight of bolts will be used.

My guess is the 750 pounder should probably use a 2000gr bolt or so, the lighter ones maybe a 1000gr, though the lightest probably should probably be in the 800gr range.

I think the 750 pounder would be pretty well representative of period 750 pound bows.

The 450 pounder might perform similar to a 300# Horn/Composite IMO, I believe the composite types had a bit longer draw than their metal counterparts.

Steel bows are often listed as having lower efficvinecy factors than wood or composite - but from what I have been told, studies about "recovery speed" of bow limbs shows almost no difference regarding construction materials. I think the reduced efficency factos of steel bows and higher efficiencies for composites has as much to do with their tolerances and flexibility than anything else. My guess is while steel bows of a hand held size as you mention Tod have a 6-7 inch maximum tolerance, a composite horn type crossbow of similar size would have a few more inches of "powerstroke" available, hence the greater "efficiency factor".

Hey guys, if you have a chance to also record exit velocity speeds I'd be real interested. I've tested a formular on a handful of replica and modern bows, and it seems pretty accurate, though as the bolts/arrows get lighter it seems to be off a bit, giving a bit slower than tested exit velocities. For example that Extocet Crossbow made by excalibur with a 22.5" draw (powerstroke + brace) has a tested exit velocity of 350 fps, I get a 334 with calculations, but this is using an incredibly light projectile for the bow, 360 grain.

The formula seems to work a lot better when using heavier bolts and arrows in the 900+ grain range.

Based on the above draw lengths and pound pulls, and the grain bolts I mentioned, the exit velocities should be in the 176-190 fps range, the lighter bow at the bottom end. Just guessing, but these might be a tad bit slow.

I would think the efficiency of the bow would drop too as lighter projectiles are used - The 750 pound bow with a light 1250
grain projectile would have an exit velocity more in the 218 fps range, faster than with a heavier bolt but overall less efficient transfer of energy.

But as I said, if you can record the exit velocities and the grain weight of projectiles this would be real interesting as well!
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Sean Manning




Location: Austria
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PostPosted: Mon 02 Feb, 2009 11:18 am    Post subject: Re: Crossbows effective versus Plate?         Reply with quote

Ben P. wrote:
I'm thinking Western Europe from 1330-1690 (With a draw weight around 400-600 pounds) Also how effective where they against Lamellar and a Lorica Laminata?

We know that quality plate was often proofed against crossbows, but a "light white harness" or the thinner parts of a heavy one might have been penetrated under favourable conditions. I estimated that the siege crossbow Payne-Gallwey tested with a draw of 1200? lbs had a 'muzzle energy' of at least 200 J. Williams estimates that 2 mm of Milanese medium-carbon steel plate could resist about 240 J from an arrow, and the padding and clothing behind it adds even more resistance. A 3 mm breastplate could resist 540 J.

More tests will be intersting to see!
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Leo Todeschini
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PostPosted: Mon 02 Feb, 2009 11:44 am    Post subject:         Reply with quote

That would be great Glennan, I will keep you both posted as to whether I can get my act together.

Quote:
Gary Teuscher wrote
My guess is while steel bows of a hand held size as you mention Tod have a 6-7 inch maximum tolerance, a composite horn type crossbow of similar size would have a few more inches of "powerstroke" available, hence the greater "efficiency factor".


I don't think so. If you look at the position of the nut, they seem pretty comparable in draw length.

As regards testing, I will be straight up. I have a big market in 6 weeks for which I have to prepare and the windlass bow will hopefully be part of this which is why I will have it and a few other bows around at the time, but it also means that I won't have that much time in which to mess about and later in the year I may have the time, but not necessarily the bows..... We will see and I will do what I can, but I also fully recognise that this a study that should be well done, but maybe between the 3 of us we can put something half meaningful together.

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Randall Moffett




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PostPosted: Mon 02 Feb, 2009 12:11 pm    Post subject:         Reply with quote

Tod,

You know what my schedule is more or less like so just give me a bit of warning and we will get something together!

Sean,

I think that 200j is off for a two foot crossbow. Liebel in Springalds and Great Crossbows averages these two foot crossbows at 331J on impact. My guess is you'd be in a world of hurt in 2mm even in that good of a suit. 540J now that would I guess keep one pretty well.... Liebel has the giant crossbows at 627j. impact.

RPM
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Gary Teuscher





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PostPosted: Mon 02 Feb, 2009 12:46 pm    Post subject:         Reply with quote

Quote:
I don't think so. If you look at the position of the nut, they seem pretty comparable in draw length.


Do you have any 11th - 13th century composite crossbow illustrations or even better finds to base this on? If so I'd be very curious.

I guess the other thing I am think is that a "slimmer" composite type bow of lighter draw weight (300-400 fot pound range) could have a longer draw than one of a substantially higher pound pull, like the 600-700 range.

I guess what I am thinking of is along the lines of where a longbow is not drawn nearly as a ratio to the length of the bow as a composite recurve bow is.
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Sean Manning




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PostPosted: Tue 03 Feb, 2009 10:17 am    Post subject:         Reply with quote

Randall Moffett wrote:

Sean,

I think that 200j is off for a two foot crossbow. Liebel in Springalds and Great Crossbows averages these two foot crossbows at 331J on impact. My guess is you'd be in a world of hurt in 2mm even in that good of a suit. 540J now that would I guess keep one pretty well.... Liebel has the giant crossbows at 627j. impact.

RPM

The figure comes from a “spherical cow” calculation which ignored air resistance but gives a lower bound. I'd guess the original energy was closer to 300-400 J. Then again, the calculations assume a hit perpendicular to the plate. I'll have a look at that book you cite- I haven't seen many crossbow tests published.
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Gary Teuscher





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PostPosted: Tue 03 Feb, 2009 10:54 am    Post subject:         Reply with quote

Based on Williams numbers, 175 is needed for 2mm of mild steel plate, which seems to have been a more "common" thickness. Maybe add another 10 for the doublet, 185 total. As these numbers by Williams use a short bodkin type of piercing object, and that was the most common form for heavier crossbows, it would seem to work right (I would think the use of a 4 sided pyramidal head by the real heavy bolts was the best route over the broadhead used by the earlier ones - just a hunch but it seems like this type would have less deformation than a broadhead)

I would think a 750# crossbow would probably be in the 215 joule range out of the muzzle, with a 1750 grain bolt. 1000# type around 260.

These are the hand portable types, more of as Randall refers to as the 1-foot probably. This is based on about 6-7" draw lengths not counting brace.

Mark Stretton conducted tests with heavy war arrows suggesting that they had about 80% of point blank penetration against foam targets at 60 yards and 67% at 180 yards. Bolts are a bit different ballistically,, but I would think in a 60 yard range they would be pretty similar.

If this accurately applies to heavy crossbow bolts, it would suggest 172 for the 750 pounder at 60 yards, and the the 1000 pounder would be around 208.

This would suggest the 750 pounder would be borderline at best at 60 yards, though the 1000 pounder would still have penetration capability at that range.

Of course, a 1mm arm or leg piece of armour would be another story, and from what I have read breastplates were not the same thickness throughout, so I guess a lot would depend on where exaclty it hit.

Iron of course would be a heck of a lot easier to pierce, more in the 80 joule range according to Williams.
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Nat Lamb




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PostPosted: Tue 03 Feb, 2009 2:18 pm    Post subject: scale         Reply with quote

James R.Fox wrote:
Sir-In that period the rachet steel scossbow (they had spring steel then) went up to 1000lb draw weight. They could smash plate, let alone mail or scale.

My understanding was that scale was actually more resistant to arrows/bolts than plate due to flexibility and the effective "double layering" you get in most paterns. I seriously doubt this would be enough to stand up to a 1000lb draw cross-bow , just saying
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Gary Teuscher





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PostPosted: Tue 03 Feb, 2009 2:56 pm    Post subject:         Reply with quote

Not really any tests on Scale or Coat of Plates or Lammelar that I am aware of other than a backyard type test, though well done for one of those. There were a lot of things that were off, but the Scale (unlayered) held up similarily to plate of 1.2mm, I don't recall the scale thickness but it was similar I think. Here is the test:

http://www.currentmiddleages.org/artsci/docs/...esting.pdf


While there are a few things with it that are inaccurate, I think it does show how scale holds up vs. thin plate.

Now with 2mm plate, I think the results would have been a lot different. I think similar thickness will give similar results, a bit better for scale than mail. However of course, 1mm of plate was most often of the type wron over mail and padding, not on it's own.
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