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Benjamin H. Abbott




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PostPosted: Mon 28 Jun, 2010 3:32 pm    Post subject:         Reply with quote

The tests published in The Great Warbow. It was also true for the Turkish bows tested by Adam Karpowicz.
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Glennan Carnie




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PostPosted: Tue 29 Jun, 2010 1:21 am    Post subject:         Reply with quote

I'm actually rather surprised at the (lack of) penetration achieved in these tests.

Below are some pictures of some plate shooting done by Dave Pim at Triskell, Italy, earlier this year. Now, this is not a scientific experiment, just a public display, so you can't read too much into the results.

The plate used is 1.5mm mild steel (probably about 0.16 - 0.29% carbon content), so somewhat less strong than Tod's plate. The bow used was around the 100lb draw-weght. Arrows were around 95g

As you can see, there was significant penetration of the plate, even with the lighter bows.

I would've expected far more penetration from Tod's crossbow.

I think a often-overlooked factor is the design of the arrowhead. Kinetic energy is all well and good but if it can't be effectively transferred to the target you will not get the penetration required.







(Tod, I'll have to pop up one evening and put some arrows into that plate off my bow and see what the differences are!)
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Leo Todeschini




PostPosted: Tue 29 Jun, 2010 11:55 am    Post subject:         Reply with quote

Glennan Carnie wrote
Quote:
I would've expected far more penetration from Tod's crossbow.

I think a often-overlooked factor is the design of the arrowhead. Kinetic energy is all well and good but if it can't be effectively transferred to the target you will not get the penetration required.



So would Tod. This is the problem with history, there is so much of it and so little time to thoroughly look at any aspect unless you have the get up and go like Randall to do a Phd. The bolts heads are of a form that is conventionally regarded as armour piercing, the bolts are as far as we can guess the right weight give or take a few grams, I have weighed the bows so I know that they are drawing to those weights give or take a few pounds and I have measured the steel thickness.

The first bow draws to a smidge over 6" which is pretty comparable to war bows, the second to 5 3/4" which is a touch under the norm but not miles away.

When I make bows I have to consider safety and longevity so as part of this I wax the strings very heavily to help bind them, but have not yet measured to see how much weight this adds, but the next one of these big ones I do, I will weigh the string before waxing and after and shoot it before and after and see what changes this makes, as this is the only obvious area I can see where it differs significantly from originals.

As regards bows, this is where my advanced maths really lets me down. The area under the power curve is of course the decider and although 850lb is a big number, 6" draw is a small number whereas 120lb is quite a big number, 28" is also a big number, especially if my conversations with Steve Stratton are remembered correctly the weight on a war bow comes on at the beginning so that 70 or 80lb are encountered after only a few inches.

The other aspect is the flexing 'hammer drilling' effect of a longbow arrow that a bolt cannot have due to its relative stiffness, so maybe they just never had the penetration that a longbow arrow had.

I feel a Phd coming on; anyone interested?

Tod

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Mikko Kuusirati




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PostPosted: Tue 29 Jun, 2010 12:30 pm    Post subject:         Reply with quote

Glennan Carnie wrote:
I think a often-overlooked factor is the design of the arrowhead. Kinetic energy is all well and good but if it can't be effectively transferred to the target you will not get the penetration required.

Actually, it's the other way around: for maximum penetration, you want the minimum of energy transferred to the target. The more kinetic energy transferred from the projectile to the target, the faster the projectile slows down; the faster the projectile slows down, the less it penetrates.

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Jean Thibodeau




PostPosted: Tue 29 Jun, 2010 12:55 pm    Post subject:         Reply with quote

Mikko Kuusirati wrote:
Glennan Carnie wrote:
I think a often-overlooked factor is the design of the arrowhead. Kinetic energy is all well and good but if it can't be effectively transferred to the target you will not get the penetration required.

Actually, it's the other way around: for maximum penetration, you want the minimum of energy transferred to the target. The more kinetic energy transferred from the projectile to the target, the faster the projectile slows down; the faster the projectile slows down, the less it penetrates.


Right one wants more energy in the projectile for better penetration and a point design that cuts through the material with the least amount of energy wasted so that it keeps on penetrating deeper and deeper.

Where one wants energy to be transferred quickly to the target is when one want maximum hydrostatic chock to the target like with an expanding bullet. Armour piercing bullets and deep penetration mean no expansion and a very hard and pointy bullet.

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Glennan Carnie




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PostPosted: Tue 29 Jun, 2010 12:57 pm    Post subject:         Reply with quote

Mikko Kuusirati wrote:
Glennan Carnie wrote:
I think a often-overlooked factor is the design of the arrowhead. Kinetic energy is all well and good but if it can't be effectively transferred to the target you will not get the penetration required.

Actually, it's the other way around: for maximum penetration, you want the minimum of energy transferred to the target. The more kinetic energy transferred from the projectile to the target, the faster the projectile slows down; the faster the projectile slows down, the less it penetrates.


Quite right Mikko; that's what I meant to say.

By 'effective transfer of energy' I meant 'cutting open the plate', not 'imparting energy into the plate'
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Mikko Kuusirati




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PostPosted: Tue 29 Jun, 2010 1:05 pm    Post subject:         Reply with quote

Glennan Carnie wrote:
Mikko Kuusirati wrote:
Glennan Carnie wrote:
I think a often-overlooked factor is the design of the arrowhead. Kinetic energy is all well and good but if it can't be effectively transferred to the target you will not get the penetration required.

Actually, it's the other way around: for maximum penetration, you want the minimum of energy transferred to the target. The more kinetic energy transferred from the projectile to the target, the faster the projectile slows down; the faster the projectile slows down, the less it penetrates.


Quite right Mikko; that's what I meant to say.

By 'effective transfer of energy' I meant 'cutting open the plate', not 'imparting energy into the plate'

Right, my misread then - naturally, our target here should not be the armour plate itself, but the soft pink flesh behind it. That's what we actually want to hit, the blasted armour just happens to be in the way. Happy

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Glennan Carnie




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PostPosted: Tue 29 Jun, 2010 2:13 pm    Post subject:         Reply with quote

Just did some very quick calculations, based on linear draw-force curves (for simplicity):

An 850lb crossbow with a 6" stroke gives about 30% more power than a 120lb bow drawing 32".

A non-linear (early draw-weight) draw-force curve for the bow would probably add about 10 - 15% more power; reducing the crossbow's power advantage to about 23%

But surprisingly, not as much power advantage as you would imagine.
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Randall Moffett




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PostPosted: Tue 29 Jun, 2010 7:37 pm    Post subject:         Reply with quote

An interesting result for the testing. I have some ideas that may or may not change anything.

Bolt types. Not only weight and head design but also the shaft. There clearly are a number of heads, and bolt types for crossbows in period as we, just as with arrows, came in a number of forms. We need to be careful with many of the remaining crossbow bolts as most/many are intended for hunting, which as with bows are likely different. The same goes for crossbows that are remaining. I am not sure of the draw lengths as well- would it be any different either for hunting or war?

To be honest I think crossbows need a major review in an academic sense. The last work focused just on crossbows to any meaningful way was The Crossbow by Payne-gallwey. For one I think we will find they were in martial use for longer than P-G indicates.

Springalds and Great Crossbows has testing done with some crossbows for initial and impact energy which seem to show that a 400lb crossbow has a tad more joules (131j) than a 140lb warbow (123j). Whereas I am not sure how that stacks to your results coupled with his models for higher draw weights 750-850lbs should have joules in the several hundreds at least which does not seem to be the case. That said the joules of energy are only one factor in armour penetration. I think Glennan's idea of trying more heads is a good one. Just a quick review of the twenty or so bolt heads I have handled make me think you might have better luck with another head. I will look for a good picture and post it here or pm it to you.

RPM
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Aleksei Sosnovski




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PostPosted: Tue 29 Jun, 2010 10:24 pm    Post subject:         Reply with quote

Bolt heads really matter. Just compare pictures of tested bolts and arrows in this thread. The bolts are simply blunt. They also seem to be thicker. I would advise sharp heat treated bolt heads with either diamond or triangular cross section of the point (so that there are sharp edges that can cut metal instead of blunt edges of square cross section that can only tear) and relatively long "neck" between the widest part of the point and the comparably wide part of the socket so that once the thickest part of the point has penetrated the bolt has some free space to move forward before the socket jams in the hole and starts expanding it. The arrow points in this thread are a good example of what I mean.
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David Pim




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PostPosted: Wed 30 Jun, 2010 5:52 am    Post subject:         Reply with quote

As the archer who carried out this demo I'd like to add a few comments of my own. The arrows were shot from a bow drawing very nearly 120lbs @ 32". Arrowheads were by Jaroslaw Belza and were sharpened and case-hardened by me. Average arrow mass was 95g. Although it looks from the photo that most arrows have barely penetrated, in fact all had penetrated up to the shoulder and have been shaken loose from the plate by the impact of subsequent strikes. The one arrow that has penetrated well may have struck a pre-existing hole, something that I feel is not taken into account sufficiently when considering the effects of massed archery on the battlefield. It may be of interest to note that this photo was taken early on in the day, whereas by the end of the day, the plate had been pounded essentially flat by the repeated impact of heavy arrows. I have attempted to attach a photo sent to me by Jaroslaw Belza, showing the penetration of steel plate by two different arrows shot from the same (Turkish) bow, showing better penetration by the narrower arrow shaft.

Cheers, David



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Aleksei Sosnovski




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PostPosted: Wed 30 Jun, 2010 10:43 pm    Post subject:         Reply with quote

Yes, the smaller the arrow/bolt diameter the better the penetration. However there are some things that should be taken into account.

1) Arrow may penetrate the steel but be stopped by the padding (and here sharp edges make even bigger difference than when penetrating steel!).
2) Arrows that penetrated only up to the shoulder are very unlikely to inflict a serious would. In fact in case of breast plate they will probably not even touch the body.
3) Most armor parts are very rounded, so arrows are very likely to simply glance off. This is especially true for arms and legs, that were usually covered by thinner steel.
4) Smaller plates are less likely to be penetrated than large ones. Try testing lamellar armor made of 1.5mm steel (with some soft padding of course). I think none of the arrows will penetrate. I shot lamellar made of 1mm mild steel with my 90lb @ 30" bow (well, it is a fiberglass recurve, so less effective than a good wooden longbow of same draw weight, and arrows were around 55 grams), none of the arrows penetrated enough to inflict a wound other than a bruise and a scratch. Judging by the distortion of the armor I think most of the energy was wasted on bending the plates and tearing leather thongs connecting them. Well, the padding was probably too soft to adequately imitate human body, but even with more rigid padding the result would most likely be similar.

However I agree that arrows striking a place already hit by another arrow could be a serious issue in case of massed fire. My arrows, though not penetrating, left big holes in the armor because of torn thongs and dented plates.
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David Pim




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PostPosted: Thu 01 Jul, 2010 5:25 am    Post subject:         Reply with quote

Yes and no. It's true that these heads penetrated only about 2.5", so if your padding was that thick then the points wouldn't have touched you. Yes thinner shafts penetrate better but are more prone to breakage than stouter shafts when striking tough surfaces. In support of those who believe arrowhead design plays a significant role, I notice that the kinds of plate-cutting bodkins I use tend to dig in and cut the plate even when striking at a fairly oblique angle - over the course of the afternoon's shooting I only had one arrow bounce off the plate, and that when it struck the very outer edge. Every other strike went in even if the plate gradually became pounded flatter and flatter as time went on. I also note that significant amounts of arrow energy were absorbed by the plate during this flattening process, whereas real forged armour would have been stiffer and less prone to flattening, both because of the forged structure of the iron/steel and because of the shape of the breastplate. I believe it likely that this would mean more kinetic energy would be available for cutting and penetrating.
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Jean Henri Chandler




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PostPosted: Wed 07 Jul, 2010 6:49 am    Post subject:         Reply with quote

Leo Todeschini wrote:


So would Tod. This is the problem with history, there is so much of it and so little time to thoroughly look at any aspect unless you have the get up and go like Randall to do a Phd. The bolts heads are of a form that is conventionally regarded as armour piercing, the bolts are as far as we can guess the right weight give or take a few grams, I have weighed the bows so I know that they are drawing to those weights give or take a few pounds and I have measured the steel thickness.

The first bow draws to a smidge over 6" which is pretty comparable to war bows, the second to 5 3/4" which is a touch under the norm but not miles away.

When I make bows I have to consider safety and longevity so as part of this I wax the strings very heavily to help bind them, but have not yet measured to see how much weight this adds, but the next one of these big ones I do, I will weigh the string before waxing and after and shoot it before and after and see what changes this makes, as this is the only obvious area I can see where it differs significantly from originals.

As regards bows, this is where my advanced maths really lets me down. The area under the power curve is of course the decider and although 850lb is a big number, 6" draw is a small number whereas 120lb is quite a big number, 28" is also a big number, especially if my conversations with Steve Stratton are remembered correctly the weight on a war bow comes on at the beginning so that 70 or 80lb are encountered after only a few inches.

The other aspect is the flexing 'hammer drilling' effect of a longbow arrow that a bolt cannot have due to its relative stiffness, so maybe they just never had the penetration that a longbow arrow had.

I feel a Phd coming on; anyone interested?

Tod


Tod,

Please continue to update us as to how your testing goes, particularly if you do some tests with a non-waxed string and different types of bolts. Also please let us know if you hear anything from your client who was doing testing.

A few comments.

I think we have a ways to go yet to figure this out, I really appreciate Tod and some others efforts to begin to look at this. i suspect so far we are missing something, though no idea what.

The crossbow draw weight of 850 lbs is indeed a big number, but it is still a bit lower than a lot of the Renaissance arbalests, which as we know were often up to 1,200 lbs draw or more. Just something to keep in mind.

From what I understand, most of the antique bolts that have been found from the Renissance are around the same wieght, roughly twice the weight of a longbow arrow on average although there are also many diifferent types. Not a whole lot more than that though, I've never heard of any all-steel bolts.

Regarding the longbow / armor tests... 1.5 mm mild steel is a litle thin for say 15th century armor. From what I've seen, a range of 1.8 - 2mm for tempered steel, and anywhere from 3 - 4mm for non-tempered steel, and up to 6mm for iron (probably the equivalent of mild steel).

You can see studies of hundred of antique examples here:

http://books.google.com/books?id=GpVbnsqAzxIC...mp;f=false

1.5 mm mild steel is probably pretty accurate for munitions grade and possibly for some horse armor though.

J

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David Pim




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PostPosted: Wed 07 Jul, 2010 7:17 am    Post subject:         Reply with quote

There's no argument here, clearly 1.5mm mild steel in no way represents armour. I am not an armour expert , but it is my understanding that 14th century armour was mostly wrought charcoal iron, which should in any case have a different structure from modern mild steel. I am sure that most armour would have been considerably thicker over vital areas, but 6mm? I am not shooting a particularly heavy bow, and I'd expect 140-160lb draw-weight bows to have considerably more penetration at close ranges than I am currently achieving.
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PostPosted: Wed 07 Jul, 2010 11:55 am    Post subject:         Reply with quote

One thing we do know is that the armour thicknesses used where considered sufficient to counter the threat.
If it was not, it would simply have been increased, in the same manner as when faced with gunpowder.

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Jean Henri Chandler




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PostPosted: Wed 07 Jul, 2010 12:21 pm    Post subject:         Reply with quote

David Pim wrote:
There's no argument here, clearly 1.5mm mild steel in no way represents armour. I am not an armour expert , but it is my understanding that 14th century armour was mostly wrought charcoal iron, which should in any case have a different structure from modern mild steel.


6mm is 17th Century cuirasser armor which basically wrought iron. That is the only armor I know of being tested which was wrought iron, from what I understand armor in the 15th Century was mostly steel, but I've mostly read about the 15th - 16th Century, I'm not thatt familiar with 14th Century armor, maybe somebody else here can chime in on that.

Quote:
I am sure that most armour would have been considerably thicker over vital areas, but 6mm? I am not shooting a particularly heavy bow, and I'd expect 140-160lb draw-weight bows to have considerably more penetration at close ranges than I am currently achieving.


I'm not an archer but I've heard from some people in the UK who are that the 'sweet spot' for English warbows / longbows, in terms of performance, is around 125 lb. Above that draw weight, I'm told, you begin to see diminishing returns. Just anecdotal though I don't have any data on that.

J

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Randall Moffett




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PostPosted: Wed 07 Jul, 2010 1:23 pm    Post subject:         Reply with quote

Todd,

After looking at even more crossbow bolts I think the points are just a bit flat for the points. They seem to have angles that are a bit low. I have some notes on crossbows and bolts etc. I looked at in museums I am trying to find but I have found some OK pictures of bolt heads for you. I will try finding my external hard drive to find some more for you.

Elling,

Not quite. You have to factor in cost and other economic factors, which is a major factor in military equipment even today this argument gets a bit more shaky. As well most/all armour is not intended to make you 100% invincible but make you able to take the most common weapons most of the time. The idea any armour could deal with all weapons 100% of the time is just unrealistic and likely impossible or the soldier would be immobile.

The argument in reverse would also be true following that logic and they both cannot be correct.

Jean,

Only at the end of the 15th was most armour steel. Excluding the armours from Italy during the 2nd quarter of the 15th and German masters about the 3th, iron was still very common in the 15th, making up nearly all of the unmarked pieces. By the late 14th steel was more and more common but once again we are looking at things that likely had a very high end clientèle. I will admit my info is almost completely the Knight and the Blast Furnace so it could be limited a bit.

Through the 15th my guess is that 2-3mm would be the average thickest part of a breastplate but once again I need to increase my sample size but so far seems fairly reliable. Breastplates easily get to 1-1.5mms though. The Avant suit in Glasgow is around 4mm so they do get thicker for higher end work.

I am not sure that 125lbs is really a sweet spot. I know people who draw much more than that and they seem, if the archer has good control, to increase in power very well.

RPM
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Jean Henri Chandler




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PostPosted: Wed 07 Jul, 2010 1:57 pm    Post subject:         Reply with quote

I guess maybe it depends what you mean by steel, aren't most of the 15th Century German armor pieces in Knight and the Blast Furnace at least .2 - .3 %carbon? It's been a while since I've looked at it...?

There is a distinction between low and medium carbon steel, tempered steel, and wrought iron.

I remember the Italian armors were proofed to two different standards, I think the German as well. So it would be a matter of what grade of armor you were talking about...

Lets see

http://books.google.com/books?id=GpVbnsqAzxIC...mp;f=false

on Page 66 he lists about 50 Italian armor without a makers mark. 4 pieces were iron, 21 low carbon steel, 19 were medium carbon steel, and 12 had some kind of heat treatment.

On page 64 he concludes a section (partly missing from the Google books) of what I think was German armor, 4 were iron, 33 were low carbon steel, 35 high carbon; 45 were at least partly hardened, 27 were not heat -treated.

J

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Leo Todeschini




PostPosted: Wed 07 Jul, 2010 2:11 pm    Post subject:         Reply with quote

Jena Henri Chandler wrote
Quote:
The crossbow draw weight of 850 lbs is indeed a big number, but it is still a bit lower than a lot of the Renaissance arbalests, which as we know were often up to 1,200 lbs draw or more. Just something to keep in mind.

From what I understand, most of the antique bolts that have been found from the Renissance are around the same wieght, roughly twice the weight of a longbow arrow on average although there are also many diifferent types. Not a whole lot more than that though, I've never heard of any all-steel bolts.


I am not so sure of your numbers here Henri,

Payne Gallwey says he tested a 1200lb bow but I think this is a bit high for most bows. the prod on the 850 was 48 x 15 x 730 which is about right for most bows, a 1200lb bow would be about 18mm thick for these dimensions and most were not this thick.

As for the bolts, most bolts in museums that have sqaure/diamond profile heads are about 65g and 400mm long and so I assume that these were 'standard' battle field bolts, that presumably went with standard windlass bows. From earlier in this thread I think it was mentioned that longbow arrows are about 95g which sounds about right and I think a 180g bolt would be massively overweight for a 'normal' bow.

I have made a string for another 850 I have in a slightly different way that will lighten it and I will lightly wax this and let you know what I find. There is no order for this bow so I won't be able to test this until I make one, unless I find the time and it fits my bow, in which case I can swap it in and give it a test shoot. I will keep you posted of anything I do.

Randall, any information is very gladly accepted and very appreciated.

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