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Jean Thibodeau




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PostPosted: Thu 15 Jun, 2006 7:24 am    Post subject:         Reply with quote

Carl Scholer wrote:
Thank you for the thoughtful reply. It helps explain how earlier, low draw weight, composite crossbows were competitive against other bows.

I think your numbers are a little off though with regards to the velocities and weights of the bolts involved in your tests. In this test you use a 175 lb steel prod crossbow to propel a 467 grain bolt to a stated velocity of 181fps.

http://www.uccrossbows.com/2006testingplate.html

In the test you just mentioned you used a 450lbs steel prod crossbow to propel a 445 grain bolt to 190 fps.

To sum up your 175lbs bow is putting out bolts with 46 joules of KE and your 450lbs bow is putting out bolts with 48 joules of KE. If these numbers are accurate then you are getting practically nothing extra out of your 450lbs bow compared to your 175lbs bow. If this is really what is happening then you might try experimenting with heavier bolts to see if you are getting all the power you can out of your heavier crossbows.


I tend to agree here just because of the math: The only thing that make a difference for momentum is mass times velocity, or Momentum= Mass X Velocity. We could complicate things making the comparison to Kinetic energy instead which is Ke=MV2 or mass X velocity squared. Just high school physics here and believe me past basic algebra I' m lost.

At these low velocities, and very close velocities, Ke won't be an important factor compared to Momentum differences.

A bolt at 2X velocity will have 4X the Ke but only 2X the Momentum at equal weight of bolt.
A bolt 2X the mass and the same velocity as a lighter bolt will have 2X the Momentum also, BUT only 2X the Ke.
So high Ke numbers of light projectiles at much higher velocity give impressive Ke numbers but can have very low Momentum numbers. With high velocity bullets, high kinetic energy can show an explosive effect and make very and fast bullets effective. Also a lot of Kinetic energy is transformed to heat on impact as opposed to momentum that has more effect on penetration. ( The old fast / slow bullet argument read a million times in Gun magazines i.e. .45 versus 9mm )

The only way for a bolt of equal weight to show dramatically more effect on target, the velocity has to be substantially greater. Or, at the same velocity you are shooting a much heavier bolt. The draw weight only makes a difference if the projectile ends up going faster or transfers more Ke or Momentum to the bolt.

In real life a small loss of velocity can be more than compensated by a big increase in mass of projectile.

Two projectiles can have identical Ke but very different Momentum: A very light projectile at a very high velocity with the same Ke as a heavy much slower projectile, the light projectile can ( Will ? ) have much less Momentum.

So, I don't dispute the effects your are seeing on target but if the bolts are very close in weight and the velocity is also close, there should be no observed difference on target !? So, all I can see here is that one of your measurements is off somehow ???

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David Ruff




Location: Denton TX
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PostPosted: Thu 15 Jun, 2006 8:42 am    Post subject:         Reply with quote

Jean Thibodeau wrote:
Carl Scholer wrote:
Thank you for the thoughtful reply. It helps explain how earlier, low draw weight, composite crossbows were competitive against other bows.

I think your numbers are a little off though with regards to the velocities and weights of the bolts involved in your tests. In this test you use a 175 lb steel prod crossbow to propel a 467 grain bolt to a stated velocity of 181fps.

http://www.uccrossbows.com/2006testingplate.html

In the test you just mentioned you used a 450lbs steel prod crossbow to propel a 445 grain bolt to 190 fps.

To sum up your 175lbs bow is putting out bolts with 46 joules of KE and your 450lbs bow is putting out bolts with 48 joules of KE. If these numbers are accurate then you are getting practically nothing extra out of your 450lbs bow compared to your 175lbs bow. If this is really what is happening then you might try experimenting with heavier bolts to see if you are getting all the power you can out of your heavier crossbows.


I tend to agree here just because of the math: The only thing that make a difference for momentum is mass times velocity, or Momentum= Mass X Velocity. We could complicate things making the comparison to Kinetic energy instead which is Ke=MV2 or mass X velocity squared. Just high school physics here and believe me past basic algebra I' m lost.

At these low velocities, and very close velocities, Ke won't be an important factor compared to Momentum differences.

A bolt at 2X velocity will have 4X the Ke but only 2X the Momentum at equal weight of bolt.
A bolt 2X the mass and the same velocity as a lighter bolt will have 2X the Momentum also, BUT only 2X the Ke.
So high Ke numbers of light projectiles at much higher velocity give impressive Ke numbers but can have very low Momentum numbers. With high velocity bullets, high kinetic energy can show an explosive effect and make very and fast bullets effective. Also a lot of Kinetic energy is transformed to heat on impact as opposed to momentum that has more effect on penetration. ( The old fast / slow bullet argument read a million times in Gun magazines i.e. .45 versus 9mm )

The only way for a bolt of equal weight to show dramatically more effect on target, the velocity has to be substantially greater. Or, at the same velocity you are shooting a much heavier bolt. The draw weight only makes a difference if the projectile ends up going faster or transfers more Ke or Momentum to the bolt.

In real life a small loss of velocity can be more than compensated by a big increase in mass of projectile.

Two projectiles can have identical Ke but very different Momentum: A very light projectile at a very high velocity with the same Ke as a heavy much slower projectile, the light projectile can ( Will ? ) have much less Momentum.

So, I don't dispute the effects your are seeing on target but if the bolts are very close in weight and the velocity is also close, there should be no observed difference on target !? So, all I can see here is that one of your measurements is off somehow ???


Agreed, this is why i posted with i know the math people are going HUH?!?!?!?. Only thing i can think of is i am hiting soft spots or something else i am doing is off. The suggestion that i am using to light a bolt on the heavier bow is a very good suggestion and could very well be the case. I need to get bigger tips and have never done so, nor have i tested heavy tips. All i do know is the 175 failed to pierce 12 ga where the 450lb does it with no issue and has enought punch into 18 ga backing behind it.


Perhaps there is a factor coming off a heavier bow that allows the bolt to retain energy better at higher draw? im not sure.

I do know this however, in the 175lb bow i used 1075

With the 450 i am using soft plate

I do not know if the 1075 was tempered - perhaps it is and that is the difference. I will fire on the 1075 this evening with the 450lb and see what happens. I will also make a heavy tip and fire again and see if that helps and what effect it has on speed of the bolt. I believe the heavies missiles found and recorded have been in the 4 to 5 oz range - maybe it is time i make a heavy.




David
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Carl Scholer





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PostPosted: Thu 15 Jun, 2006 11:33 am    Post subject:         Reply with quote

Yes, momentum is a much better way of gauging penetration than KE. Unfortunately KE is just so popular that all the arrow against armour tests I have seen are measured in terms of Joules/Newton Meters. I just didn't want to confuse everything by throwing around Newtons when everything I've stated up to this point is in terms of Joules. Although one of the funnier things with bows is that you usually get a KE boost when you increase the weight of the arrow (thatís not the reason why I suggested heavier bolts for the heavier crossbow though). By increasing the weight of the projectile you are increasing the efficiency of the system (bow and arrow), these tests kind of illustrate the effect.

http://www.atarn.org/islamic/akarpowicz/turkish_bow_tests.htm

Also David, technically, the only way the energy of your crossbows is being represented in your bolts is in the velocity they are imparted with, it can't manifest itself in any other meaningful way. How the bolt retains its velocity is decided first and foremost by its shape and initial velocity.

This test illustrates some of the mechanics involved in bow and arrow efficiency... its kind of a hard read though Eek!

http://www.bio.vu.nl/thb/users/kooi/kobe97.pdf
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Jean Thibodeau




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PostPosted: Thu 15 Jun, 2006 11:49 am    Post subject:         Reply with quote

David;

There is no magic involved in the sense that the bolt would know that the crossbow it is being shot from is a 100 at 1000 or even a 10000 pounds of draw: Now heavier prod, everything else being equal, should give you more power unless all the power is being wasted just moving itself Eek! If it's giving a heavy but slow " push " all that energy is not doing anything if it is not moving your bolt faster unless you are using a heavier bolt.

O.K. I'm repeating myself here. Wink

Big IFF: If you have a 4 oz bolt moving at 200 ft/sec shot from one crossbow and a 4 oz bolt at 200 ft/sec at the same 200 ft/sec using a crossbow with a draw 3X the first one, you have exactly the same amount of Ke / momentum. Oh, and a very heavy crossbow whose limb are not moving the string any faster.

Since I think you seem to be getting more out of the heavy crossbow using the same bolts at the same weight: Then your bolt has to be moving faster for you to get any different results. My best guess would be that your measuring of bolt speed is giving you erroneous numbers.

Though if you can double the weight of bolt with an insignificant loss of velocity you would be almost doubling the amount of Momentum. Like you said in a very early post: With no bolt on the crossbow the speed of the bow string will be at it's maximum, adding a bolt will slow down the string by a very small amount but even a much heavier bolt might mean only loosing a few ft/sec of velocity. The ideal crossbow bolt is the one giving you the most amount of momentum even at the cost of some speed. At some point increasing the bolt weight hits the point of diminishing returns where the lost off velocity will be great enough that your bolt will loose speed AND momentum.

I don't have to have any special knowledge of crossbows function, it's just external ballistics that counts: The internal ballistics deals with the efficiency of the launching system.

Anyone out there with a degree in physics please feel free to correct any mistakes I may have made in my argument or something I have not taken into consideration.

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Jean Thibodeau




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PostPosted: Thu 15 Jun, 2006 12:13 pm    Post subject:         Reply with quote

Carl Scholer wrote:
Although one of the funnier things with bows is that you usually get a KE boost when you increase the weight of the arrow (thatís not the reason why I suggested heavier bolts for the heavier crossbow though). By increasing the weight of the projectile you are increasing the efficiency of the system (bow and arrow), these tests kind of illustrate the effect.


Exactly and not because the arrow goes faster but because at almost the same speed the arrow has more mass.

With the formula Ke = Mass x V2 we tend to focus on increasing speed with modern rifle bullets because doubling the speed
gives you 4 time the Ke energy and 3 times the speed give you 9 times the Ke: So there is a tendency to focus on speed to increase Ke and forget that increasing mass also increases Ke. Eek!

When the extra mass causes a loss of velocity there is a point above which there is a net increase of Ke until the increase of mass slows down things to the point that Ke become less.

With the Momentum formula the point of greatest efficiency does not match the numbers that give the most Ke: There must be
a possible graph, beyond my capabilities, that would show the crossover point(s) with varying mass & velocity combinations.

The debate about Ke or Momentum giving the best penetration is very open to debate and I tend to think that for any specific case the best solution is a compromise between the two.

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David Ruff




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PostPosted: Sun 18 Jun, 2006 9:32 pm    Post subject:         Reply with quote

Jean Thibodeau wrote:
Carl Scholer wrote:
Although one of the funnier things with bows is that you usually get a KE boost when you increase the weight of the arrow (thatís not the reason why I suggested heavier bolts for the heavier crossbow though). By increasing the weight of the projectile you are increasing the efficiency of the system (bow and arrow), these tests kind of illustrate the effect.


Exactly and not because the arrow goes faster but because at almost the same speed the arrow has more mass.

With the formula Ke = Mass x V2 we tend to focus on increasing speed with modern rifle bullets because doubling the speed
gives you 4 time the Ke energy and 3 times the speed give you 9 times the Ke: So there is a tendency to focus on speed to increase Ke and forget that increasing mass also increases Ke. Eek!

When the extra mass causes a loss of velocity there is a point above which there is a net increase of Ke until the increase of mass slows down things to the point that Ke become less.

With the Momentum formula the point of greatest efficiency does not match the numbers that give the most Ke: There must be
a possible graph, beyond my capabilities, that would show the crossover point(s) with varying mass & velocity combinations.

The debate about Ke or Momentum giving the best penetration is very open to debate and I tend to think that for any specific case the best solution is a compromise between the two.



Made a heavier bodkin today and fired it off the 450lb Total bolt weight was 2.28oz or about 997gr. Speed on the bolt was not effected to really post - about 3 fps less at an average of 185fps. the tip blew through .080 thick 1050 steel, the bolt seperated at the plate and the tip carried on and made a nice little dent in the tree behind. Again - i do not know if the 1050 is tempered or in annealed state. What i do know is i am now making some 3.5oz bolts to fire.

More later when the first of the heavies come out. I have a 550lb to 625lblb sitting here ready for testing before it goes to its owner thats been awaiting it for a year now. Might fire on some plate with it.


David
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Rod Parsons




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PostPosted: Mon 19 Jun, 2006 12:24 am    Post subject: Bodkins         Reply with quote

I would also suggest using a heavier bodkin which has a cross section as large as the shaft, thereby allowing the shaft to more easily follow into the hole made by the head, rather than whittling down the diameter of the shaft body behind the bodkin.
The tip of a best quality bodkin should have steel forged into the body of wrought iron.
Mark Stretton's recent work indicates that there is no advantage in having a loose fit to the shaft when shooting at a hard target.
The shock of impact has even caused a shaft to open up the socket and come free, so reducing the mass at a crucial moment.
A loose fitting barbed head might be effective on a soft target, but it seems more practical to make the shafts to a consistent standard since you would not want the inconvenience of sorting through shafts in the heat of battle.
Rod.
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David Ruff




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PostPosted: Mon 19 Jun, 2006 1:33 am    Post subject: Re: Bodkins         Reply with quote

Rod Parsons wrote:
I would also suggest using a heavier bodkin which has a cross section as large as the shaft, thereby allowing the shaft to more easily follow into the hole made by the head, rather than whittling down the diameter of the shaft body behind the bodkin.
The tip of a best quality bodkin should have steel forged into the body of wrought iron.
Mark Stretton's recent work indicates that there is no advantage in having a loose fit to the shaft when shooting at a hard target.
The shock of impact has even caused a shaft to open up the socket and come free, so reducing the mass at a crucial moment.
A loose fitting barbed head might be effective on a soft target, but it seems more practical to make the shafts to a consistent standard since you would not want the inconvenience of sorting through shafts in the heat of battle.
Rod.



Thanks rod, i will look into that. I was wondering about the bodkin head being as big as the taper behind the head - but wasn't sure and need some historical referances on it.

Just for kicks after i wrote that last email i fired the 550/625lb crossbow with a 2.5oz bolt.... Hit a tree behind the target. The bolt went into it and was sticking 3" out the other side. Not sure of the tree thickness, but the total bolt length is 13.5". The tip is 3" sticking out, the rear is 6.5" sticking out. The tree was hit just right of dead center. Actually was not aiming for it. I was shooting at some plate, missed it, went through the bail and hit the tree. The bail is hay with 3 layers of carpet over it - front and back - loose not secured to the bails. The tree is a texas pecan/hickory tree. I prolly killed the tree doing that Sad

On a side note - you CAN cock a bow this heavy using a belt hook and your wife helping you to cock the bow.


I am very sure this bow would fire a heavier bolt and have more punch, and i have very little trouble believing this bow would punch right through 3mm plate, into the maille, into the arming jacket and either kill the target or make him/her wish they were dead - meaning take the fight right out of them.

Oh CHRIS!!!!! get ready for your bow Happy


David
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Rod Parsons




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PostPosted: Mon 19 Jun, 2006 1:49 am    Post subject: Re: heads         Reply with quote

David,
Email me rod@englishlongbowevents.com and I will send you illustrations of various types.
Rod.
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Jean Thibodeau




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PostPosted: Mon 19 Jun, 2006 8:01 am    Post subject: Re: Bodkins         Reply with quote

David Ruff wrote:
[Thanks rod, i will look into that. I was wondering about the bodkin head being as big as the taper behind the head - but wasn't sure and need some historical references on it.

Just for kicks after i wrote that last email i fired the 550/625lb crossbow with a 2.5oz bolt.... Hit a tree behind the target. The bolt went into it and was sticking 3" out the other side. Not sure of the tree thickness, but the total bolt length is 13.5". The tip is 3" sticking out, the rear is 6.5" sticking out. The tree was hit just right of dead center. Actually was not aiming for it. I was shooting at some plate, missed it, went through the bail and hit the tree. The bail is hay with 3 layers of carpet over it - front and back - loose not secured to the bails. The tree is a texas pecan/hickory tree. I prolly killed the tree doing that Sad

On a side note - you CAN cock a bow this heavy using a belt hook and your wife helping you to cock the bow.

David


And I still wonder about how the numbers add up ? Surprised But the results seem to indicate more Ke or momentum than the weight of bolt and velocity would indicate. I still don't see how similar weight of bolts assuming almost identical speeds can give greater results at close range from a heavy crossbow compared to a heavy longbow. ( Just recapping, and now to the point. )

I think I read before on this topic thread or a closely related one that a heavy longbow arrow might weight as much as 4 oz.: My gut feeling, not math ! Is that you might find it worth while to try progressively heavier bolts until you reach the point of diminishing returns. Maybe even up to an 8 oz bolt just to see how it performs from your heavy crossbow.

If you find the weight that gives you the most penetrating power in wood you should be able to get every possible bit of power out of the crossbows even before testing on plate.

A good book you should check out is: ANCIENT AND MEDIEVAL SIEGE WEAPONS, A fully illustrative guide to siege weapons and tactics, KONSTANTINE NOSSOW, The Lyons Press © Konstantine Nossov 2005. Very good book !

Quote page 160 : " There were undoubtedly great crossbows in the Middle Ages, too - big stationary crossbows firing long and heavy bolts and wound by means of a windlass (see plate 34 ). Several big 1.2 to 2 meter-long bolts for such crossbows have been found. dating back to the 12th and 13th centuries. "
" Since a bolt fired from a great crossbow or espringal could easily break not only any armor but any portable shield,there were not many dare-devils willing to attack a gate defended by such arrow-firers. "

Now crossbows using " bolts " 4' to 6' long have got to be " Heavy " compared to a longbow arrow and the power of the machine throwing one of these, at what I assume would be at least close in velocity, should be very great.

Now, a machine like this is artillery and not man portable and even if by some miracle a breast plate wasn't pierced, I would think that one would end up rather " PULPED " in between breast and back plate by blunt trauma.

Now, these machines might be extreme cases that one might exclude from any tests if we want to limit ourselves to what could be man portable. So maybe very heavy bolts might even be over my guesstimate of 8 oz. for a 1200 lbs crossbow ?

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Rod Parsons




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PostPosted: Mon 19 Jun, 2006 8:18 am    Post subject: Head types and padding.         Reply with quote

I have been doing a limited amount of preliminary shooting at padding and it occurs to me that careful attention will need to be paid to the shape of the bodkin.
Whilst a short nosed heavy bodkin might be effective against plate, punching a hole which the shaft can then follow on through, where there is strong thick padding on top of maille a short nosed head may well have too great a compressing effect on the padding.
Conventional wisdom names the long needle bodkin as a specific against maille, but more importantly in my view, it seems to be the type which is best at piercing thick padding and long enough to both pierce padding efficiently and long enough to also find an aperture in the maille beneath.
It will be worth comparing the performance of the long needle, the small bodkin, the large bodkin and the small type 16 barbed against heavy padding over maille.
Rod.
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PostPosted: Mon 19 Jun, 2006 11:23 pm    Post subject:         Reply with quote

Quote:
Made a heavier bodkin today and fired it off the 450lb Total bolt weight was 2.28oz or about 997gr. Speed on the bolt was not effected to really post - about 3 fps less at an average of 185fps.


That's much better - about 103 J. An arrow of similar weight shot from a 150-lb longbow would have somewhere in-between 112 J and 124 J.
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Rod Parsons




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PostPosted: Tue 20 Jun, 2006 11:51 am    Post subject: Shaft weight and efficiency.         Reply with quote

Jean,
I agree with you about increasing the weight of the crossbow bolt until the point is reached where performance falls off.
With bows the generally accepted guideline is 10 grains of shaft weight for every pound of draw weight.
This tallies with a 175 lb draw longbow shooting a 4 oz war shaft (1750 grains).
Applying the same rule to the crossbow, a 400 lb crossbow should be able to easily project a 9 oz bolt.
With the bow shooting a much lighter arrow can often leave unused energy in the limbs which can manifest itself to the archer as handshock and it is not uncommon to tame a slightly unpleasant shooting bow by using a heavier string and shaft.
Rod.
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Carl Scholer





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PostPosted: Wed 21 Jun, 2006 12:48 am    Post subject:         Reply with quote

Now that's more like it Big Grin You've pretty much equaled a 150lbs longbow with that 450lbs crossbow of yours. Also, by comparing the data you gave me on 150lbs composite crossbow to the results of a 136lbs composite bow it looks like you have almost equaled that as well Surprised All in all it's very impressive.
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David Ruff




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PostPosted: Wed 21 Jun, 2006 10:14 am    Post subject: Re: Shaft weight and efficiency.         Reply with quote

Rod Parsons wrote:
Jean,
I agree with you about increasing the weight of the crossbow bolt until the point is reached where performance falls off.
With bows the generally accepted guideline is 10 grains of shaft weight for every pound of draw weight.
This tallies with a 175 lb draw longbow shooting a 4 oz war shaft (1750 grains).
Applying the same rule to the crossbow, a 400 lb crossbow should be able to easily project a 9 oz bolt.
With the bow shooting a much lighter arrow can often leave unused energy in the limbs which can manifest itself to the archer as handshock and it is not uncommon to tame a slightly unpleasant shooting bow by using a heavier string and shaft.
Rod.


Very good point on the taking the shock out of a crossbow. I use that a lot on the lighter target bows i make.

This morning i ground down some 1/2 steel rod and made a 4.6oz total weight bolt (the goal was to make a heavy bolt) The tip was heated to red hot and quenched in water and then heated to a blue finish. The goal was to see what the crossbow would do and how it would react. The crony read 167fps. The bolt hit the steel plate and punched through it, hit the patch of maille and blew thru it and continued through the haybail. The bolt was found 37 yards behind the bail. The tip was deformed and the wood bolt cracked. The maille was drug into the bail by about 2". 7 rings were damaged and out of those 7 rings 5 were severly deformed and 2 cut in half. The shot was taken at 54 yards from shooter to target.

It should be noted that the plate was .0105" thick around the pierce and made of 1050 carbon plate that was heated to red hot where a magnet would not stick to it and then quenched in oil. It was then baked at 550 degrees for 3 hours and 20 minutes and quenched in water. The chain maille was made of very non period stainless steel that is butted and not rivited. The hay bail is damp and tight packed and 14" thick front to back. It stops 150lb crossbows.

The crossbow shot one of the smoothest and quietest shots i have fired off it. There was a very pronounced push to the bow as well when i fired. I know all this and 3.50 will get me a coffee at starbucks but it again raises the question if it did happen, it proves nothing at this point other then the fact i would not want to have been behind the plate on that shot.


David
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Jean Thibodeau




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PostPosted: Wed 21 Jun, 2006 4:04 pm    Post subject:         Reply with quote

David;

Thanks for that test as it does seem to confirm the theory that momentum of a heavy bolt at a moderate lost of velocity gives a lot of punch. I assume this is with a medium heavy crossbow you have been using in the 450 pound range ? With the even heavier 1200 pounder you are planning to make your velocity figures might be similar with an even heavier bolt.

Forgetting completely about period performance, we can still arrive at modern comparative tests of what maximizes bolt penetration in modern media. Anyway, my original title for this thread was power and range of crossbows ! And not just
" historical performance " . I'm interested in this topic to learn all I can about crossbows and not just period plate.

Obviously, tests that would correlate closely with period conditions are something to try to achieve but what we can say is that you have first hand physical evidence of what you shoot at and with what, we can each of us decide what we think it means, I hope !?

Oh, with those much heavier bolt close range power may mean a loss of potential range and a very " rainbow trajectory " at long range. For maximum range the ideal weight of bolt would probably be like your usual lighter ones.

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Rod Parsons




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PostPosted: Wed 21 Jun, 2006 4:13 pm    Post subject: Range         Reply with quote

You can get more range by going lighter but with a war shaft the lower weight limit is set by the lower threshold of energy required to still penetrate a protected target. You could use a flight shaft and go further but it would trouble no-one (suitably attired) when it arrived.
Lets see how 10 grains to the lb of draw weight penetrates and how it affects your fps.
Rod.
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Jean Thibodeau




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PostPosted: Wed 21 Jun, 2006 4:32 pm    Post subject: Re: Range         Reply with quote

Rod Parsons wrote:
You can get more range by going lighter but with a war shaft the lower weight limit is set by the lower threshold of energy required to still penetrate a protected target. You could use a flight shaft and go further but it would trouble no-one (suitably attired) when it arrived.
Lets see how 10 grains to the lb of draw weight penetrates and how it affects your fps.
Rod.


Completely agree and it would only be useful for harassing fire better done with high rate of fire longbows.

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David Ruff




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PostPosted: Wed 21 Jun, 2006 8:40 pm    Post subject: Re: Range         Reply with quote

Rod Parsons wrote:
You can get more range by going lighter but with a war shaft the lower weight limit is set by the lower threshold of energy required to still penetrate a protected target. You could use a flight shaft and go further but it would trouble no-one (suitably attired) when it arrived.
Lets see how 10 grains to the lb of draw weight penetrates and how it affects your fps.
Rod.



Rod i will try that, so i am to grind out a head that with the bolt will weight about 4500gr?

I am guessing that a 1200lb (as described in payne gallweys book of the crossbow) that a 4.5oz bolt is gonna hurt something. My issue here is i got the 70 yard range, that drops into thick forext that is about 50 to 100 yards and then businesses.... if i have a fly away im gonna kill someone hehehe. Should be noted as welkl that the payne-gallwey bow also was thought to have lost pull due to being cocked for 100's of years. I am finding that 3000lb pull hand siege bows were/did used/exsist. <--- not that crazy, if i can't do it on 1500 to 1900 - i quit :P


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Nathan Robinson
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PostPosted: Wed 21 Jun, 2006 9:10 pm    Post subject:         Reply with quote

I wish that people who are doing these modern tests would simply stay within the context of what they are doing. I want to see the stopping of definitive statements of what was done historically, how things performed throughout history, etc. The simple fact is this: such definitive statements cannot be made by shooting a modern-made projectile from a modern-made weapon into a modern-made target without significant research, understanding, and effort to faithfully recreate materials, conditions, and constructional details.

So what? There is a lot of other things that can be learned from doing such tests, including knowing what possibly could have happened historically. It can't answer that question, but it can answer others. The tests will be interesting nonetheless.

All I ask is that people doing such testing stay within the context of the tests and stop making definitive conclusions without a proper scientific method. There is a lot of value to such tests. Why make them controversial by trying to make them something they are not?

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