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Kevin S.





Joined: 25 Aug 2009

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PostPosted: Sat 18 Aug, 2012 11:33 am    Post subject:         Reply with quote

Gary Teuscher wrote:
Here is some testing of Composite crossbows. Can't comment on the quality of the mail, but otherwise seems to have been done very well and things like exit velocities and ranges are probably as accurate as anything that may be found.

Only issue I see is the lighter composite crossbow seems a bit light a draweight, under 300 pounds.

http://www.historiavivens1300.at/biblio/beschuss/beschuss1-e.htm


Hey Gary, do you know what date this interesting article was published? This could have saved me a lot of time back in 2009 :P
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William P




Location: Sydney, Australia
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PostPosted: Sat 18 Aug, 2012 9:49 pm    Post subject:         Reply with quote

ive also double checked my byzantine manual,
it says that in archery there are three goals to shoot accurately to shoot powerfully to shoot rapidly

nowhere does it explicitely mention the ability to cast the arrow at long range as being really important, it sounds like from this that, archers seem to be expected almost to be kind of like snipers, rather than just bombarding an area.

it gives a great deal of emphasis regarding the method of draw, and puts emphasis on POWER rather than range specifically.

curiously it talks about archers shooting while moving but it doesnt seem to specify or hint at whether the instructions are meant for foot or mounted archers..

are there many sources or indeed ANY for training crossbowmen or describing how crossbowmen were trained.
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Gary Teuscher





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PostPosted: Mon 20 Aug, 2012 9:26 am    Post subject:         Reply with quote

Quote:
It uses Indian mail just like all the other mail tests. I've already given a list of why it is not appropriate for weapons tests. The mail weave is also stretched way too tight which further reduces its weapon resistance.


Yeah, I was not looking at it from a weapons testing standpoint, there always seem to be too many errors there in many tests.

I was more interested in bolt weight, initial velocity, draw length/draw weight etc. This helps give comparisons to a longbow and steel crossbows.

Quote:

Hey Gary, do you know what date this interesting article was published? This could have saved me a lot of time back in 2009 :P


No Idea at all Kevin, unfortunately.

Quote:
But from those posted, ~ 95 J of energy with pretty heavy bolt would put over 600 pound crossbow, with very decent draw lenght, around maybe 110 pound longbow.


?? maybe we are reading this but seeing different things.

Quote:
Maximum speeds were 53 m/sec for crossbow 1, 61 m/sec for crossbow 2.

Bolt speeds ranged, depending on bolt weight, from 39 to 50 m/sec for crossbow 1, and from 46 to 55 m/sec for crossbow 2.


Hard to see exactly what is being said, but from the above info I'd go with 55m/sec for the lightest of the bolt with the heavier crossbow.

Quote:
Lancelet head with rhombic cross section at a shaft of larch wood with feathers of willow

Head broadness: 9mm
Head thickness: 5mm
External nozzle diameter: 13mm
Head length: 87mm
Overall length: 381mm
Mass: 41g


The lightest bolt is 41g

I get 124 Joulles when mutipliying this out. And I think the crossbow would be most efficient (i.e. generate more joulles) with a heavier bolt, one of the other 3.
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Bartek Strojek




Location: Poland
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PostPosted: Mon 20 Aug, 2012 11:16 am    Post subject:         Reply with quote

Well, it seems you've just forgotten to divide it by 2.

Velocity squared times bolt mass gives 124 - and by 2 we're getting 62.

And yeah, I meant that with just "velocity varying from...." there's a lot of assumptions, they had also mentioned that their bow had rather quickly taken significant set - dunno if inducement in velocity is already factored in.
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Gary Teuscher





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PostPosted: Mon 20 Aug, 2012 1:41 pm    Post subject:         Reply with quote

Quote:
Well, it seems you've just forgotten to divide it by 2.


Duh! Blush


Do we have some velocities and arrow weights for longbows to compare?

I'd guess the arrows (not flight) for longbows were in the 60-95 gram range, and velocities in the 45-50 m/sec range?
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Lafayette C Curtis




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PostPosted: Mon 20 Aug, 2012 11:03 pm    Post subject:         Reply with quote

William P wrote:
ive also double checked my byzantine manual,
it says that in archery there are three goals to shoot accurately to shoot powerfully to shoot rapidly

nowhere does it explicitely mention the ability to cast the arrow at long range as being really important, it sounds like from this that, archers seem to be expected almost to be kind of like snipers, rather than just bombarding an area.

it gives a great deal of emphasis regarding the method of draw, and puts emphasis on POWER rather than range specifically.

curiously it talks about archers shooting while moving but it doesnt seem to specify or hint at whether the instructions are meant for foot or mounted archers..


That's not really surprising. Procopius's accounts of 6th-century Byzantine wars against the Sassanid Persians mention one battle where the (presumably armoured) horse archers on both sides engaged in an archery duel. The Persians shot faster but the Byzantines shot with more power, and after a while (if I'm not mistaken) the Persians were forced to retreat. Procopius also states that the "Roman" archers of his time drew to the ear, unlike the shorter draw (and less powerful shots) of Classical Greeks.

Finally, considering the importance of horse archery to the Byzantines at this point (Procopius credited their victories against the Goths in sallies before the gates of Rome to the "Roman" troops' horse-archery capabilities, as compared to the Goths who had only javelins and spears), I'd expect that shooting on the move does refer to horse archery.

Come to think of it, a lack of emphasis of range wouldn't be unexpected for horse archers, since horse archery is best performed at the shortest ranges possible anyway.
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Gary Teuscher





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PostPosted: Tue 21 Aug, 2012 9:48 am    Post subject:         Reply with quote

Quote:
Depends on what efficiency we're talking about, from what I've read, wooden bows can get up to 70%. Some Karpowicz bows were apparently getting up to 80-some, but that's all with pretty 'perfect' loose.


The efficiency numbers I used for crossbows (58% and 64%) were more off the cuff just for determing the relationship between steel, wood, and composite.

Though it looks like the composite tested bows are roughly 14% more efficent (80/70) per the numbers you give.

Of course, I think Crossbows will be in general less efficient, the biggest reason being the bolt compared to pound draw.

One thing also though - I think wood crossbows were in great use even in the 13th-15th centuries. There is a record of a town in Northern France replacing it's wooden crossbows with steel ones in the late 15th century.

While Composites and Steel bows were out there during their heyday, it seems the wooden types were out there as well.
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Gary Teuscher





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PostPosted: Tue 28 Aug, 2012 11:58 am    Post subject:         Reply with quote

Well, I must say after reviewing the Composite Crossbow tests from the aforementioned site, it seems that 400 pounds of draw is roughly equivalent to a 100 pound longbow based on the info given in Soar regarding Mark Strettons testing.

The only thing is the Composte Crossbow testing is rather vague in it's numbers, failing to mention which bolts were used.

I wish there would be more specifics on the crossbow testing, but at least it is something to go by.

So if at Crecy the English longbows were the 150 pound variety drawn to about 30", they should have outranged the crowwbows drawn by a simple belt and claw which might be in the 300 pound range. The heavier ones that would require a pulley as a mechanical aid would be approximately similar to a 150 pound longbow, perhaps a bit stronger.

Much as I have thought the crossbow was superior to the longbow in strength, I must say the little bit of testing that is out there points the other way.
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Benjamin H. Abbott




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PostPosted: Tue 28 Aug, 2012 12:39 pm    Post subject:         Reply with quote

Note that the bow Stretton used in Soar's book performs somewhat worse than the Mary Rose replicas tested in The Great Warbow and that the composite crossbow figures discussed above are likely anomalous. The efficiencies are just too low. I suspect at least the better quality period crossbows performed much better. There's no reason why Payne-Gallwey's 1200lb steel crossbow should be more efficient than a 616lb composite crossbow. If you apply a crude measure of that steel crossbow's efficiency (kinetic energy divided by power stroke times weight) to the composite, you get 173 J minimum. That strikes me as a better figure for a 616lb composite bow. We know crossbow bolts routinely pierced mail, so they must have managed at least 120 J.
Out of doubt, out of dark to the day's rising
I came singing in the sun, sword unsheathing.
To hope's end I rode and to heart's breaking:
Now for wrath, now for ruin and a red nightfall!
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Gary Teuscher





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PostPosted: Tue 28 Aug, 2012 12:53 pm    Post subject:         Reply with quote

Quote:
the composite crossbow figures discussed above are likely anomalous. The efficiencies are just too low.


That does seem to be a bit odd, their low efficiencies. I might run the numbers if enough is out there to see the efficiency of both Payne-Gallweys 1200 pound monster and the above composites. The 1200 pound monster should be less efficient, primarily due to draw vs bolt weight. Remember though, that 1200 pound monster had a pretty long draw in comparison as well.

Quote:
(kinetic energy divided by power stroke times weight)


Should be draw length, not powerstroke, and take out the brace length as a percentage of draw weight. Funny, everyone uses power stroke only for crossbows and draw length for hand bows - that's like comparing apples and oranges.

Quote:
We know crossbow bolts routinely pierced mail, so they must have managed at least 120 J.


Two things here - do we know they "routinely" pierced mail? Or is that more of an assumption? And also, what crossbows pierced mail? Steel bows have more power, and they may well pierce mail, but that does not mean composites do.

The other thing - With Williams testing, the 120j would be required to pierce mail, but that is with the pyramidical head he used. Testing with heads of actual bolts/arrows used would be more relevant.

It's very possible a more bodkin style head could pierce at 90j.

Just a thought here - I'd think the bodkins would pierce mail better than the head williams used. When plate came more into the game, the bodkin style would not be effective, at least against plate.

But I must again add, I wish there was more testing of composite bows. They were made with period materials, but we don't know how well they were made compared to bowmakers of that time.
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Bartek Strojek




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PostPosted: Tue 28 Aug, 2012 1:09 pm    Post subject:         Reply with quote

Well, in what sense is 616 composite crossbow is more efficient than steel crossbow of 1200 pounds though?

Pound for pound it would be on average quite probably more efficient both in storing energy and transfering it to the arrow, but total output would be still way bigger for 1200 pounder, due to two times bigger draw weight, obviously. Just not two times.

Quote:
There's no reason why Payne-Gallwey's 1200lb steel crossbow should be more efficient than a 616lb composite crossbow. If you apply a crude measure of that steel crossbow's efficiency (kinetic energy divided by power stroke times weight) to the composite, you get 173 J minimum.


I remember that Harmuth in "Die Armbrust" was reporting something along those 170-180 J for ~1100 pounds steel bows.

Dunno if it's available somewhere in the net, I've never really read it due to my German being abysmal, though. Joules and numbers are universal, at least. Big Grin


Quote:
It's very possible a more bodkin style head could pierce at 90j.


There probably would be quite interesting variation and dependency between shape of the head, overall mass/dimensions and dimensions/construction of the rings.

Some thin bodkins would probably be best answer for larger rings, just to try to 'slip' trough indeed.

Interestingly, in already linked test, lightest and least powerful bolt is only one to penetrate at least a bit - and it's indeed the slimmest one!
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Gary Teuscher





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PostPosted: Tue 28 Aug, 2012 1:25 pm    Post subject:         Reply with quote

By using velocities of 10% below maximum for the Heavier composite, and middle of the road weight on the bolts (65g), we are looking at 102 joules from the projectile.

We can use "Die Armbrust" values of 175 Joules for a 1100 pounder with a 10" draw, 3" brace, 7" Powerstroke.

The heavier Composite is a 8" power stroke, use the same 3" Brace, 11" Draw.

The 1100 pounder stores 458 foot pounds, the Composite stores 282 foot pounds.

On a joule to foot pound ratio (LOL), the 1100 pounder comes in at 38%, the Composite at 36%.

(It's amusing I look at joules for energy released but foot pounds for energy stored, but comparatively it works fine)

The formula used to calculate stored energy is not 100% accurate, as it includes the brace as part of the draw, but it is accurate from a comparative standpoint.

Just looking at this, it indeed seems to me the composites should come out better. They should bleed less efficiency due to their projectile being heavier compared to stored energy (Unless the Die Armburst bows are using a 120 gram or so projectile), and most deem composites to be more efficient than steel bows.

I would think the Composites should compare better than the steel bows, maybe at the 40-44% range or so. This may have to do with the manufacture of the composite by a "rookie", and it may also have a bit to do with the vague numbers we have regarding velocities and weights of the projectiles in the composite tests.


ETA - I wonder what the maker of the crossbows in the testing could do if they spent all of their time making these crossbows and trying to perfect them, testing for velocity? I wonder if 10 years from now, the performance of their crossbows would be better?
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Benjamin H. Abbott




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PostPosted: Tue 28 Aug, 2012 7:21 pm    Post subject:         Reply with quote

Gary Teuscher wrote:
Remember though, that 1200 pound monster had a pretty long draw in comparison as well.


If I recall correctly, it had a powerstroke of 5.5 inches. That's considerable shorter than the 9-inch powerstroke for the 616lb composite. By my calculations, Payne-Gallwey's shot would require 208 J in a vacuum. The atmosphere should increase this to 230ish J or more, but I'll use the lower figure.

Payne-Gallwey
1200 x 5.5 = 6600
208/6600 = 0.0315

Heavy composite
616 x 9 = 5544
95/5544 = 0.017

Die Armbrust
1100 x 7 = 7700
175/7700 = 0.0227

By this admittedly rough assessment, the Payne-Gallwey bow is 85% more efficient. That's weird. Of course, it's also 39% more efficient than the Die Armbrust bow. And all of this is using the vacuum energy figure.

Quote:
Should be draw length, not powerstroke, and take out the brace length as a percentage of draw weight.


I don't understand this. Powerstroke is draw length minus brace height, and the relevant measure. How do you take out brace length as a percentage of draw weight?

Quote:
Steel bows have more power, and they may well pierce mail, but that does not mean composites do.


The wildest claims about crossbow power come from the era of composite prods, not the era of steel prods. Writing in the middle of the sixteenth century, Fourquevaux consider bows and crossbows interchangeable and equivalent.

Quote:
But I must again add, I wish there was more testing of composite bows. They were made with period materials, but we don't know how well they were made compared to bowmakers of that time.


Exactly.

Out of doubt, out of dark to the day's rising
I came singing in the sun, sword unsheathing.
To hope's end I rode and to heart's breaking:
Now for wrath, now for ruin and a red nightfall!
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William P




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PostPosted: Tue 28 Aug, 2012 11:51 pm    Post subject:         Reply with quote

Lafayette C Curtis wrote:
William P wrote:
ive also double checked my byzantine manual,
it says that in archery there are three goals to shoot accurately to shoot powerfully to shoot rapidly

nowhere does it explicitely mention the ability to cast the arrow at long range as being really important, it sounds like from this that, archers seem to be expected almost to be kind of like snipers, rather than just bombarding an area.

it gives a great deal of emphasis regarding the method of draw, and puts emphasis on POWER rather than range specifically.

curiously it talks about archers shooting while moving but it doesnt seem to specify or hint at whether the instructions are meant for foot or mounted archers..


That's not really surprising. Procopius's accounts of 6th-century Byzantine wars against the Sassanid Persians mention one battle where the (presumably armoured) horse archers on both sides engaged in an archery duel. The Persians shot faster but the Byzantines shot with more power, and after a while (if I'm not mistaken) the Persians were forced to retreat. Procopius also states that the "Roman" archers of his time drew to the ear, unlike the shorter draw (and less powerful shots) of Classical Greeks.

Finally, considering the importance of horse archery to the Byzantines at this point (Procopius credited their victories against the Goths in sallies before the gates of Rome to the "Roman" troops' horse-archery capabilities, as compared to the Goths who had only javelins and spears), I'd expect that shooting on the move does refer to horse archery.

Come to think of it, a lack of emphasis of range wouldn't be unexpected for horse archers, since horse archery is best performed at the shortest ranges possible anyway.


but there is barely any clue as to whether the instructions about archery refer to foot or horse archery it almost sounds like its meant to more or less apply to both equally... maybe..
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Gary Teuscher





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PostPosted: Wed 29 Aug, 2012 9:24 am    Post subject:         Reply with quote

Quote:
I don't understand this. Powerstroke is draw length minus brace height, and the relevant measure. How do you take out brace length as a percentage of draw weight?


With a straight line increase in draw (Meaning a 45 degree straight line), and a 100 pound draw with 30" of draw, you should have 0 pounds at 0" draw, 50 at 15", and 100 pounds at 30". Draw is not entirely straight line, varies bow to bow, but is usually roughly a 45 degree line.

However, a 30" draw bow with a 15" brace (entirely unusual, but picked for easy math) starts not at 0 pounds at 15", but at 50 pounds. So therefore, the draw is not 15" of powerstroke, x 100 pounds, but divided by 2 - it is 15", x 75 pounds.

The 75 is the average of starting draw weight (50 pounds), and the ending draw of 100, and again is assuming straight line increase.

So what you really need to do is NOT multiply powerstroke by draw weight - but muliply draw weight by drawlength. And with a 10" draw and a 3" brace, and assuming straight line increase in force, the draw begins at 30% of draw, so the draw is not draw weight divided by 2, but the draw weight muliplied by 65%. And indeed here you simply muliply by the "powerstroke", as you are taking the brace out of the equation.

However, have you noticed whenever someone looks at the force stored by a selfbow, they take the draw length times draw weight divided by 2? They are inaccurately leaving the unused brace in the equation.

Both selfbows and crossbows have braces, and both need to be factored in (or out I guess).

A simpler but less accurate method often used is simply multiply draw weight by draw length by draw weight and divide by 2. This method is commonly done with Selfbows. However, when this simple method is used with crossbows, they use powerstroke as opposed to drawlength. Again, Apples and Oranges.

Quote:
If I recall correctly, it had a powerstroke of 5.5 inches. That's considerable shorter than the 9-inch powerstroke for the 616lb composite.


I thought the Bow used by Payne Gallwey had a loger powerstroke, at least 9" and was more of a siege weapon. I did not have the specifics on it, which is why I used the Die Armbust numbers for steel bows. Would you have the specifics on the Bow Payne Gallwey used?


ETA: I might add to complicate the above force calculations - recurve bows are a slightly different story. A straight bow only desires as a spring to get straight again - while a recurve desires to get past straight to it's initial unbraced state. This means that straight recurves are already a bit "drawn".

In essense what it means is that you add a few inches of draw length to a bow, depending on it's degree of recurve - you also add a few inches of brace, the same that you added to draw. Exacly how to calculate would be based on physics that I am not sure how to calculate exaclty, but adding a few inches to draw does this in rough fashion.

This is one reason why composites (which are pretty well always recurves) come out with a higher efficiency rating than non recurves, which include the standard English Longbow. It's also another reason why composite crossbows should be more efficient than wood or steel - though they do not have the same degree of recurve as some composite self bows.
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Benjamin H. Abbott




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PostPosted: Wed 29 Aug, 2012 5:41 pm    Post subject:         Reply with quote

Gary Teuscher wrote:
With a straight line increase in draw (Meaning a 45 degree straight line), and a 100 pound draw with 30" of draw, you should have 0 pounds at 0" draw, 50 at 15", and 100 pounds at 30". Draw is not entirely straight line, varies bow to bow, but is usually roughly a 45 degree line.

However, a 30" draw bow with a 15" brace (entirely unusual, but picked for easy math) starts not at 0 pounds at 15", but at 50 pounds. So therefore, the draw is not 15" of powerstroke, x 100 pounds, but divided by 2 - it is 15", x 75 pounds.

The 75 is the average of starting draw weight (50 pounds), and the ending draw of 100, and again is assuming straight line increase.


Thanks for the information.

Quote:
And indeed here you simply muliply by the "powerstroke", as you are taking the brace out of the equation.


How much does this matter when comparing crossbows? Isn't the brace fairly similarly at least across types? I guess the composite prods might have a bit more a brace, but we're not comparing crossbows and hand-drawn bows here.

Quote:
Both selfbows and crossbows have braces, and both need to be factored in (or out I guess).


Yeah, definitely. I don't see how multiplying draw weight by draw length is any better than multiplying powerstroke by draw length. Both fail to completely account for the brace. Like you, I'm only shooting for a decent back-of-the-envelop formula, not a precise assessment.

Quote:
I thought the Bow used by Payne Gallwey had a loger powerstroke, at least 9" and was more of a siege weapon. I did not have the specifics on it, which is why I used the Die Armbust numbers for steel bows. Would you have the specifics on the Bow Payne Gallwey used?


I was wrong; it's 7 inches (page 14). No mention of the brace. And I was misremembering the kinetic energy measurement as well. It only takes 173 J to send a 84g projectile 460 yards in a vacuum. 208 J is a rough attempt at factoring air resistance in. That's what I get for not looking at my notes. These two errors make the Payne-Galwey crossbow more consistent with the other numbers, but a 1,200lb steel prod still shouldn't be shooting a 84g bolt more efficiently than a 616lb composite shoots a 90g bolt!

Out of doubt, out of dark to the day's rising
I came singing in the sun, sword unsheathing.
To hope's end I rode and to heart's breaking:
Now for wrath, now for ruin and a red nightfall!
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Gary Teuscher





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PostPosted: Thu 30 Aug, 2012 10:09 am    Post subject:         Reply with quote

Quote:
was wrong; it's 7 inches (page 14). No mention of the brace. And I was misremembering the kinetic energy measurement as well. It only takes 173 J to send a 84g projectile 460 yards in a vacuum. 208 J is a rough attempt at factoring air resistance in. That's what I get for not looking at my notes. These two errors make the Payne-Galwey crossbow more consistent with the other numbers, but a 1,200lb steel prod still shouldn't be shooting a 84g bolt more efficiently than a 616lb composite shoots a 90g bolt!


Payne-Gallwey
1200 x 5.5 = 6600
208/6600 = 0.0315

Heavy composite
616 x 9 = 5544
95/5544 = 0.017

Die Armbrust
1100 x 7 = 7700
175/7700 = 0.0227

To Correct the Payne Gallwey Bow:1200 x 7 = 8400
208/8400 = .025

This puts in roughly in line with the Die Armbrust bows, but the compound composite seems way under powered, less efficient than the steel bows. There is another bowyers article on the ability of different materials to store energy, steel is least efficent, materials used in old construction composite bows are the best, wood is in the middle. Actually, the best rankings are modern materials such as glass fibre, but irrelevant for our needs.

If the composites come out say 10% more efficient than steel, which I think is realistic. they should be at about .0275 on the above scale.

This would be 152 Joules, and would put a 65 gram bolt at about 68 meters per second.
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Benjamin H. Abbott




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PostPosted: Thu 30 Aug, 2012 2:41 pm    Post subject:         Reply with quote

Oh, it's also worth noting the Die Armbrust numbers involve a 80g bolt. Between those tests and Payne-Gallwey, we can conclude that heavy steel crossbows surpassed the all but the heaviest longbows shooting the heaviest arrows. Only with a 113.4g arrow does a 150lb Mary Rose bow manage even 146 J. A 180lb longbow with the same arrow shouldn't deliver more than 160-170 J, and I don't believe there's any evidence for heavier arrows (or bows, for that matter). Only a truly exceptional English archer could loose arrows as potent as bolts form a heavy steel crossbow, and the bolts would still be faster and thus doubly more accurate. (The crossbow's design facilitates accurate shooting, which faster projectile speed further enhances.)

On the other hand, these calculations simultaneously show that heavy steel crossbows had no reasonable chance of piercing high-quality breastplates or helmets. If I recall correctly, a 2.5mm breastplate of the very steel with padding requires around 400 J to defeat. All of this stands consistent with later period accounts of the crossbow and longbow, especially Fourquevaux's. Crossbows hit harder than longbows, but not necessarily as much harder as is often assumed.

Out of doubt, out of dark to the day's rising
I came singing in the sun, sword unsheathing.
To hope's end I rode and to heart's breaking:
Now for wrath, now for ruin and a red nightfall!
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Gary Teuscher





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PostPosted: Fri 31 Aug, 2012 8:33 am    Post subject:         Reply with quote

The other thing as well - if we take the 288 pound draw bow, and apply the same efficiency numbers that we did to the heavier composite, we should see 119 Joules.

With a 65 gram bolt, we have 60.5 meters per second for the lighter bolt.

This puts the lighter composite as very similar in performance to a 150 pound pull longbow.



Quote:
Only with a 113.4g arrow does a 150lb Mary Rose bow manage even 146 J.


I must add this is very heavy for a longbow arrow, from what I remember the estimated weights of arrows was in the 900-1500 grain range. The above arrow would weigh in at 1750 grains.

I am sure with much heavier bolts, crossbows could generate more joules, but using what is historically "accurate" is more important.

I think I agree with you, Ben. The Composite bow test listed, while interesting, seems to be off in regards to performance. At worst a composite crossbow should be equal to a steel bow in efficiency. It should theoretically be a lot better. The Composite has a recurve structure, which should make it more efficient, the materials used for a composite bow are better in terms of energy transfer. Last but not least, maybe most importantly, the composite bows should be much better in terms of weight of bolt to force applied ratio, this holds true in all bows, the Karpowicz bow testing is one of the best examples regarding this.

My guess it is something in the construction, perhaps they did not het the glueing process right or something else.

Quote:
If I recall correctly, a 2.5mm breastplate of the very steel with padding requires around 400 J to defeat. All of this stands consistent with later period accounts of the crossbow and longbow, especially Fourquevaux's. Crossbows hit harder than longbows, but not necessarily as much harder as is often assumed.


Quote:
Williams unless specified otherwise)

Energy to defeat, in Joules:

Arrowhead vs. Buff Leather 30 J
Lance vs. Cuir-boulli 30-20 J
Lance vs. Padding (16 layers linen, 60g for 16 x 21 cm) 50 J
Arrowheads vs:
Modern Mail (mild steel) alone 80 J
Modern Mail & Jack Penetration 100 J
Modern Mail and Tailor's Dummy 100 J (Soar et al)
Modern Mail, Jack Penetration, and 35 mm penetration of Plastilene behind 120 J
15th c. Mail (low carbon steel hardened by quenching) two links broken and jack behind completely penetrated: 120 J
1 mm mild steel plate (perpendicular impact) 55 J for 45mm penetration
1. 5 mm mild steel plate 110 J
2 mm mild steel plate 175 J


I'd think probably the 250 joule range would be more accurate based on the above numbers - but this is only with perpendicular impact. If not perpendicular, it's a lot tougher.

But still, if the Payne-Gallwey bow generates 206 joules, this would still make the wearer pretty safe.

Of course I don't now how superior the harness you mention is to mild steel.

And I think the head Williams used may not have given the best results for mail penetration, it would seem more accurate for me in regards to plate penetration, as the longer bodkin types would struggle with mail, and an arrowhead more like Williams tip would be better against plate.
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Benjamin H. Abbott




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PostPosted: Fri 31 Aug, 2012 2:35 pm    Post subject:         Reply with quote

Gary Teuscher wrote:
I must add this is very heavy for a longbow arrow, from what I remember the estimated weights of arrows was in the 900-1500 grain range. The above arrow would weigh in at 1750 grains.

I am sure with much heavier bolts, crossbows could generate more joules, but using what is historically "accurate" is more important.


There's at least textual evidence for the quarter-pound longbow arrow. I suspect crossbow bolts got that heavy or heavier too - at least occasionally. However, the moderately weighted bolts tested by Payne-Gallwey and the Die Armbrust folks should blow through mail & padding with a sharp head and still do some serious damage with a blunter design. And even very heavy bolts shouldn't penetrate quality plate, so perhaps there was little to gain from using a four-ounce projectile. Speed and range have their advantages. Turkish war arrows apparently rarely if ever exceeded 650 grains. Heavier arrows would have done better against armor, but there's no evidence for their use.

Quote:
Of course I don't now how superior the harness you mention is to mild steel.


Quite superior. Williams rates hardened Innsbruck steel as 50% more difficult to pierce than mild steel, and hardened breastplates were often 2.5-3mm in the important places. Because of how the energy required increases to the power of 1.6, that means a 2.5mm Innsbruck breastplate can take up to 357 J. The padding then adds an additional 50 J for a total of 400 J for a perpendicular shot to penetrate. These are approximate numbers, but make piercing high-quality armor with a crossbow rather implausible. Of course, most combatants would have made do with less specular equipment. Fourquevaux wrote that a close-range barrage of arrows or bolts might overwhelm lower-grate harnesses.

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