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Carl Goff




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PostPosted: Thu 13 Nov, 2008 11:51 am    Post subject: How fast does a composite bow's arrow reach its target?         Reply with quote

As I think I've mentioned in at least one prior thread, one of the reasons I hang out on this forum is because I'm an aspiring fantasy-fiction writer, and I want to buck the genre's trend of gross inaccuracies involving weaponry.

I've got a scene rattling around in my head where a dismounted soldier shoots one of three javelin-toting enemies standing on a ledge about thirty feet above him, and sinks the shaft to the fletching in the enemy's chest. Presuming an Oriental-style (semi-Parthian culture, if you want to get really specific) horse-archer's composite bow (say, about 75 lbs. draw weight, since I believe composite bows can have substantially lighter draw weights without sacrificing force), and that the ledge is at the following angle (I'm still calculating the exact distance in feet) from his position, how fast is the arrow going to get there, and will it still have enough force to penetrate as deeply as I'm envisioning?

Edit: Broadhead arrows are being used. Will that have any significant effect on the speed?

___
......|
......|
......|............................Archer


And on a related note, will a javelin hurled from the ledge have the range to hit the archer and still retain enough force to inflict a major injury if/when it reaches him?

Oh, East of sands and sunlit gulf, your blood is thin, your gods are few;
You could not break the Northern wolf and now the wolf has turned on you.
The fires that light the coasts of Spain fling shadows on the Eastern strand.
Master, your slave has come again with torch and axe in his right hand!
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Last edited by Carl Goff on Thu 13 Nov, 2008 5:05 pm; edited 2 times in total
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Artis Aboltins




PostPosted: Thu 13 Nov, 2008 2:23 pm    Post subject:         Reply with quote

Well, that would certainly depend on some things - main beeing, if the jawelineer has any sort of boy armour. If none, then I see no reason why not? I do not own a composite bow myself, but the arrow launched from my replica of viking-age style bow (replica of one of Haitaby finds) can launcn an arrow well over 100 m distance and has quite a bit of penetrating power at most ranges I can maintain decent accuracy... also, much would depend on arrowhead shape.
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Jared Smith




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PostPosted: Thu 13 Nov, 2008 3:23 pm    Post subject:         Reply with quote

I am guessing your estimated draw weight is pretty high for a horse bow or other type of historically accurate composite bow. I recently had to watch a group of boy scouts shoot multiple attempts of qualifying rounds of 30 arrows at a target at roughly this distance using a modern composite pulley and cable type 30 lb draw bow suitable for youth or compact use that I would imagine to be most workable from horseback. "Fifty something" pounds is probably more like it for an historical example intended for war use from horse.

There is a pretty in depth chapter on speed and energy for draw weight by Tim Baker in volume I of the Bowyer's Bible. Based on a wide range of bow types in that draw range, 150 something feet per second without significant loss of speed during the first 50 feet is believable. So, to reach a target 30 feet away, figure a little less than a quarter second (0.20 +/- 0.05 secons) from release of the arrow from the bow is in the ball park for a huge range of bow types, draw weights, and testing results regardless of assumptions that you might make. (The time it takes the bow to unflex is not included in the time... I will just guess that less than 0.5 seconds total from finger release is correct. I believe there are some charts on time it takes to move the string and develop there release energy-velocity as well. Hopefully this is adequate for your purposes.) You will have to assume a massive war bow or very light target bow to get much out of that estimate.

Absence of evidence is not necessarily evidence of absence!
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Jason Daub




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PostPosted: Thu 13 Nov, 2008 4:41 pm    Post subject:         Reply with quote

If I am recalling correctly, the maximum arrow speed for a traditional bow is around 190fps. Centre shot recurves seem to hover in the 200-210fps range and compounds are a lot faster. It seems that due to "Archer's Paradox" a correctly spined arrow weighs enough to keep the speed down. As for the draw weights, 75lbs would not be out of the question, but it would be a lot slower to shoot, modern horse archers like Kassai Lajos tend to use a light (40lbs) bow to be able to shoot rapidly and accurately from horseback. I have seen it proposed somewhere, I can't remember the source, that the heavier bows were intended to be shot from the ground.
'I saw young Harry, -with his bevor on,
His cuisses on his thighs, gallantly arm'd,-
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Jared Smith




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PostPosted: Thu 13 Nov, 2008 5:16 pm    Post subject:         Reply with quote

Some modern archers have made heavy war longbows I will just settle upon calling "plausible", but which have no proven historical counterparts to match, with 200 lb draw range that push 275 feet per second. You can get a tremendous range of arrow speed depending upon what draw weight, geometry, and arrow construction you assume. Most of the bows simulated by reconstructing artifacts' geometry in Bowyer's Bible have less than 200 feet per second speed in testing, and pile up inside a surprisingly narrow range of overall performance. There are a lot of different approaches, but human geometry sort of dictates arrow length, and manageable draw weight dictates a lot of the rest when one considers the overall result.
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Alexander Wu





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PostPosted: Thu 13 Nov, 2008 5:39 pm    Post subject:         Reply with quote

i don't see why it can't penetrate a guy...especially at 30 feet.

I shoot at a 25 meter FITA range at my University. I shoot a 60# english longbow, and a Kassai bear at 65#. Assuming the target is unarmored, it would definitely penetrate the enemy. We shot pumpkins for halloween, and my longbow shot right through those, along with the horsebow.

However, pumpkins aren't humans...and burying up to the fletchings is a bit iffy...probably not possible at that weight. A good 100+ lbs would bury it that deep.

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Joel Minturn





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PostPosted: Thu 13 Nov, 2008 6:26 pm    Post subject:         Reply with quote

Well the distance too the target will be more than 30 ft. Earlier I was trying to figure out some distances for how far away the guy would be. If he was standing 40 ft from the cliff to keep the math simple would mean the arrow would travel 50ft, but would only drop as far as if it flew 30 ft.

I don't think a 75lb bow would be unreasonable. I do believe that some of those period recurves were quite powerful. I thought they used them all from horses but guess I don't know for sure.

If the javelin had the range to reach the archer it would have enough energy to kill. The added height would help the javelin.
Now if I could find my bowyers bible and physics text book I might be able to help more.

Don't think that having broad heads would change much other than helping penetrate the target.

I think what your thinking of could be possible.
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Joe Fults




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PostPosted: Thu 13 Nov, 2008 6:55 pm    Post subject:         Reply with quote

Writing fantasy fiction, seems to me the arrow can go as fast and as deep as you want it to go. Wink
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Christopher H





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PostPosted: Thu 13 Nov, 2008 7:19 pm    Post subject:         Reply with quote

Hi Carl,

The programs at this website may be helpful to you: http://www.goarchers.org.uk/mechanics/downloads.htm
If you have a lot of technical detail I think the 'arrow' program may be of benefit to you.
At any rate, if you have some basic details and leave the rest it may give a useful estimation.
Best wishes!
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Jared Smith




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PostPosted: Thu 13 Nov, 2008 7:33 pm    Post subject:         Reply with quote

There are a couple of studies around on how well javelin can be thrown, including by those in training since youth. (It approaches 88 feet per second. Range is surprisingly far...) http://www.leshatton.org/Documents/jav2007a_paper.pdf

If the archer has to start by reaching for an unequipped arrow, I am not sure he would beat the javelin at close range. On the other hand, if both were just ready and waiting, my instinct is that the archer has a speed and spatial requirements advantage. In the original vertical alignment match up that was described, I think it would be more awkward (not your usual arcing throw) for the javelin than for the bow. You could possibly make more of an issue out of the unusual geometry for the combatants than you could over the relative speed of their techniques at close range.

Absence of evidence is not necessarily evidence of absence!
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Jean-Carle Hudon




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PostPosted: Fri 14 Nov, 2008 9:22 am    Post subject:         Reply with quote

Carl,
using broadheads would have an impact on your storyline because you mentionned that the chest is the point of impact. Chest implies ribcage, whereas our pumpkin shooting friend is thinking gutwound. Hitting the softer abdominal area would allow for deeper penetration than the chest where the probable impact on the ribcage would affect the broadhead's penetration.
The javelin, being thrown at a target from a stationary position on a ledge, cannot be treated the same way one treats a modern sport javelin, being thrown after acceleration with the usual technical niceties. When you try for a target with one of A&A's javelin points, twenty steps is about the maximal range for any consistency, but throwing with gravity aiding should permit more velocity, and thus more distance with a certain degree of precision, especially as your premice is that these javelin throwing fellows know what they are doing. A convenient fantasy tree nearby could help your archer greatly, cutting down the need for ressuscitation and other wizardly involvment....tell us when it's done and published. Cheers. Jean-Carle.

Bon coeur et bon bras
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Benjamin H. Abbott




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PostPosted: Fri 14 Nov, 2008 11:38 am    Post subject:         Reply with quote

Quote:
I am guessing your estimated draw weight is pretty high for a horse bow or other type of historically accurate composite bow.


I doubt this. The debate over draw weight still rages, but you'll find plenty of evidence for heavy composite bows, both physical and textual. I suspect archers in any warrior culture to pull bows about as powerful as those used on the Mary Rose. Now, they may have used significantly lighter weapons on horseback, perhaps only two thirds as heavy as on foot. I recall folks claiming primary source support for this notion, thought I haven't seen it myself. If correct, the still yields bows in the hundred-pound range.

Depending on arrow weight, such composite bow can shoot amazing fast. See these tests by Adam Karpowicz. 300 fps and over.

As for the scenario, both javelin and arrow would be deadly to unarmored men at that range. Either projectile would reach its target in a fraction of a second. I don't know about burying up to the feathers, though. Using a heavier English longbow, Mark Stretton's arrows didn't do this against a pig carcass. They were shot into the shoulder.
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Leo Todeschini
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PostPosted: Fri 14 Nov, 2008 12:58 pm    Post subject:         Reply with quote

Just as a slight aside

When my friends am I have had a few too many beers we shoot at each other with blunt arrows (rubber ends). At about 25 yards or more off 60-75lb lonbows you can step aside from the arrow; interestingly if two people shoot at you you cannot track both shots and either you choose one to avoid, or usually you are distracted because you know the other is coming and you lose tracking on both.

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Lafayette C Curtis




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PostPosted: Sat 15 Nov, 2008 9:42 am    Post subject: Re: How fast does a composite bow's arrow reach its target?         Reply with quote

Carl Goff wrote:
(say, about 75 lbs. draw weight, since I believe composite bows can have substantially lighter draw weights without sacrificing force)


Lighter? Yes, perhaps. Substantially lighter? Maybe not. Many surviving Turkish and Manchu war bows have been reconstructed to produce bows with draw weights of 120 lbs. or more, and original war bows that are in sufficiently good condition to be strung and drawn often show similarly high draw weights as well.


Quote:
how fast is the arrow going to get there


Modern extrapolations from Taybugha al-Ashrafi's medieval Mamluk archery treatise show that Taybugha wanted an archer to be able to shoot at a target about 75 yards away with a trajectory not exceeding 8 feet in height, so the desired arrow speed would have to be 180 fps or more at the time it left the bow. You can extrapolate from there to the situation you have in mind, taking care to factor in the extra height and the high parabolic trajectory needed to hit.


Quote:
and will it still have enough force to penetrate as deeply as I'm envisioning?


Against an unarmored man? Lethal penetration, yes. Penetrating to the feathers, I'm not so sure.


Quote:
Edit: Broadhead arrows are being used. Will that have any significant effect on the speed?


Probably not over such short distances.


Quote:
And on a related note, will a javelin hurled from the ledge have the range to hit the archer and still retain enough force to inflict a major injury if/when it reaches him?


If the javelin thrower is good, yes!


Jared Smith wrote:
I am guessing your estimated draw weight is pretty high for a horse bow or other type of historically accurate composite bow. (snip) "Fifty something" pounds is probably more like it for an historical example intended for war use from horse.


75 lbs. actually sounds pretty typical. Very powerful archers might be able to handle 100lb. or 130lb. bows on horseback but only for short periods, and I suspect 50-80 lbs. to be the most practical range of draw weights for use on horseback because horse archery is rather more tiring than foot archery, especially if you have to anticipate a need to engage in hand-to-hand combat; 75 pounds is well within this range.


Benjamin H. Abbott wrote:
I doubt this. The debate over draw weight still rages, but you'll find plenty of evidence for heavy composite bows, both physical and textual. I suspect archers in any warrior culture to pull bows about as powerful as those used on the Mary Rose.


Not quite--only those who had to contend with the problem of armored targets, long range, or (most likely) both could be guaranteed to need such powerful bows. But I agree that archery cultures that did face those problems generally ended up developing fairly heavy war bows and the techniques needed to use them effectively.


Quote:
Now, they may have used significantly lighter weapons on horseback, perhaps only two thirds as heavy as on foot. I recall folks claiming primary source support for this notion, thought I haven't seen it myself. If correct, the still yields bows in the hundred-pound range.


It still "yields bows in the hundred-pound range" only if you use the heaviest bows in the Mary Rose finds. If you use the heaviest typical bows--those that fall around the 140-pound range, which is quite close to the weight of most heavy war and flight bows found in Turkish arsenals--you'd end up with something around 93 pounds, which is quite a bit below 100 pounds. That'd be rather light for a war bow meant for use on foot, but (again, I suspect) quite heavy for horsebow standards.

There's been a rather lengthy discussion about this subject in the ATARN forums, with pointers to possibly relevant primary sources:

http://198.170.107.188/phpBB2/viewtopic.php?t=1033&start=0
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Bartek Strojek




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PostPosted: Sat 15 Nov, 2008 11:16 am    Post subject: Re: How fast does a composite bow's arrow reach its target?         Reply with quote

Carl Goff wrote:
and will it still have enough force to penetrate as deeply as I'm envisioning?


I think it's more up to you - it depends on size and "durability" of target's chest, as humans can be very different in that matter, and also what do you mean by broadhead.

I believe that exact shape of arrow is very important in this matter.

There is also exact place of hit, angle, hitting (or not) the ribs that matter and other such details.

So perhaps in "ideal circumstances" such shot would be possible.
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Benjamin H. Abbott




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PostPosted: Sat 15 Nov, 2008 7:44 pm    Post subject:         Reply with quote

Quote:
Not quite--only those who had to contend with the problem of armored targets, long range, or (most likely) both could be guaranteed to need such powerful bows. But I agree that archery cultures that did face those problems generally ended up developing fairly heavy war bows and the techniques needed to use them effectively.


I'm sure it doesn't apply to all groups. Those requirements sound reasonable. Note that the Amerindians of what's now the southeastern United States seem to have draw extremely powerful bows despite not having much if any armor to worry about.

Quote:
you'd end up with something around 93 pounds, which is quite a bit below 100 pounds.


It is? Sounds close enough to me. I think you're just arguing for the sake of arguing. 150 pounds appears repeatedly in The Great Warbow as the average draw weight for late English bow. 100 is exactly two thirds of 150. As I said, though, I see little difference between 93 pounds and 100 pounds. Considering how individual bows vary, you'd be hard pressed to distinguish between two such weapons based on performance.
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Lafayette C Curtis




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PostPosted: Sat 22 Nov, 2008 4:17 am    Post subject:         Reply with quote

Well, I didn't say that I agreed with the idea that a horsebow ought to draw two-thirds the weight of an infantry bow--if anything, I'd bet my money on the idea that a cavalry bow optimally draws about half the weight of a good, strong infantry bow, as the Turkish examples (which are sometimes clearly marked to distinguish infantry from cavalry bows) show.

Of course, that's just my opinion, and only applies as long as we're talking about military bows.
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Benjamin H. Abbott




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PostPosted: Sat 22 Nov, 2008 9:57 am    Post subject:         Reply with quote

Well, according to that source from the Ming period, even the weak archers drew almost eighty pounds, while the strongest drew over a hundred and fifty.
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JE Sarge
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PostPosted: Sat 22 Nov, 2008 10:22 am    Post subject:         Reply with quote

Published science fiction author and bow hunter here (among other things...lol).

I know very little about historical specs concerning this, but I can say that anything flies in your creative endeavor. Unless you are being outlandishly silly about this, your reader will buy it. You just have to sell your readers on what you are writing.

Now, I have fired at a target with longbows, recurves, and highly specialized compound bows and I can honeslty tell you that anything beyond 30-40m is sheer luck for most, no matter the draw weight or arrow type - but the mythology and biased ancient literature skews the modern view of this. You can use this to your advantage though in your story. Think about this:

Guy throws javelin as bowman is aiming for him. Javelin hits bowman and bowman falls, loosing arrow. Arrow appears to fly upward into the sky appearing to miss javelineer, but fatefully falls back to the earth and kills javalineer as he rejoices in his kill. They still essentially killed one another.

Just an idea though...

Good luck with your writing!

J.E. Sarge
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