Yes the RA sells an English one for 10-15 pounds.

RPM

An interesting discussion evolved about this on another forum, which included some possibly useful data.

This essay

http://www.deremilitari.org/resources/articles/ekdahl.htm

which is based on data culled from the voluminous records of the Teutonic Order in the Baltic, had some interesting tidbits. This is an interesting description of how crossbows were used in combat in the Baltic:

Quote:

In the case of a long range shot of something like 300m the bolt, after about nine seconds, struck the ground steeply at an angle of 70 degrees. Although the energy on impact fell to about half the initial energy, th shot was still effective up to 200m (source footnote 121) At the beginning of a battle the crossbow bolts were shot diagonally upwards for a distance of about 200m towards the enemy lines. Among the hail of normal bolts it was also the practice to include Heulbolzen (whistling bolts) which produced a sharp whistling sound; in the Order's records they re referred to as Bremsen (gadflies)(source footnote 122) Their purpose was to weaken the enemy and their hoses psychologically, and to casue confusion. This effect was not produced by the sound as such, bu tby the fact that experience had shown that there was a relationship between the sound and pain; (snip) After such a punishing hail of bolts at the beginning of a battle, the crossbowmen moved forward in order to take aimed shots at a distance of up to 80m, and thus to contribute to the further course of the battle. The great difference from the English longbowman lay iin the often decisive fast that the longbowmen could shoot six or seven arrows before a crossbowmen could get off one shot (if they had mechanical winders) (source footnote 123)"

The article goes on to describe different types of crossbows:

Quote:

In the fifteenth century, to compete with the longbow and the emerging use of firearms, the crossbow was equipped with a powerful steel bow, with the help of which the draw-weight increased to up to 500 kg. In the case of the stirrup crossbow with a horn bow, the draw-weight was up to 150 kg.107 The strong steel bows could be drawn only with the special help of mechanical devices such as a windlass (the so-called 'English winder') or the ratchet winder (the so-called 'German winder' or cranequin). Even after 1450, the crossbow was in no way inferior to hand-held firearms, and it was also used as a weapon of war in the sixteenth century.

The article (and two other sources I have based on these same Teutonic Order records, one of them being the Osprey book on the Teutonic Order) mentions four distinct types of military crossbows : Knüttelarmbrüste used from at least the 12th Century through the 16th. Made with a simple Yew prod. Marginally capable as a military weapon, similar to a modern hunting crossbow. This is the weapon which is usually compared to a longbow.

Composite prod stirrup crossbow aka 'Steigbügelarmbrust' . Spanned with a stirrup, made of semi-composite wood bow reinforced with baleen and / or sturgeon 'horns'. Later (stronger) composite prods were made uses goat foot ('Geissfuss') or belt-hook to span. made of wood, sinew, rams horn, bull horn, and other materials. Up to 150 KG draw.

Windlass siege crossbow "English Winder", large powerful composite prod crossbow but very slow to span with a cord and pully 'Seilrolle' or Windlass 'Winde', popular in the 14th Century for seige warfare, gradually discontinued in the early 15th century. 300-500 KG draw.

Steel prod or heavy composite arbalest uses cranequin aka "German winder" smaller than the other types. Usable from horseback. 500 KG draw.

Estimates from several sources have given me a bolt weight at 70-90 grams. An initial velocity was estimated close to 65 m/s for a 500 KG crossbow.

All of this will be trumped by some realistic field testing. This historical data is useful context though I think.

J

Anything new on this?

Not yet from me I am afraid

Tod

some backyard tests from a 450 lbs draw "arbalest" made out of a leaf spring from a minivan, shooting very large bolts. Sorry for some of the cheesy aspects of the video, the penetration seems to be quite good though.

http://www.youtube.com/watch?v=xMFtSIvbnPk

This also sheds light on a couple of other things such as the effects of the heavier projectiles I think.

J

Now that was impressive and sort of what I was talking about as to heavy bolts. ;)

450 lbs draw is heavy but far from the maximums one might expect from a tripod mounted huge crossbow but it does give a good general idea about what to expect. ( Bolt velocity over 200 feet per second and closer to 300 is also an indication that the heavy bolts are not so heavy as to be slow and seem optimized to the power of the prod ).

Rate of fire is not that slow either but we are influenced by our modern expectations about how fast is fast loading and shooting.

From a prepared position with enough obstacle to slow down the advance of an enemy force this rate of fire should be more than adequate and even more so if there is a line of a large number of these firing ( Loosing ) together or alternating in more of a rolling fire style if fired individually instead as coordinated volleys.

Supported by a shield wall, pike square and lighter equipped smaller crossbows, archers and/or handgunners these would be useful as field artillery.

That bow is 415lbs as they state and so perhaps half of the draw weight of a medieval war bow, however the power stroke on that bow looks to be 16 to18" as against the 6.5-7" stroke on a medeival war bow and that changes everything. I made a ballistrino at 320lbs draw weight, but it was not shooting 75% of this one shown on youtube as it only had a 1 3/4" draw. So this clip is interesting and fun, but from a historical view point doesn't show anything I am afraid.

I do have two more 850lb bows to make over the next 2-4 months so I will test and report back what I discover.

I will also at some point make a ballistic pendulum and post up raw data for those interested - not sure when though.

Tod

Well historically you are correct about the length of power stroke but just design wise it makes me wonder why the power stroke would have been historically so short and inefficient ? If one is making one's prods short in length then it makes sense since too long a power stroke would overstress the break the prods ? So there must have been a reason to use shorter prods ?

Makes some sort of sense for hand carried crossbows to keep their size manageable but for tripod mounted siege crossbows using much longer and efficient prods seems more effective to me ?

Very puzzling ? But in any Medieval Alternate Universe World I was creating for myself I would find the crossbow shown irresistibly tempting to use whatever was done historically. ( But then if creating historical reproductions one is restricted to historical accuracy ).

Prod of the arbalest in the video seems to be rather inefficient. Seems to have neither distal nor profile taper, very wide at the ends. there seems to be another smaller "prod" that keeps center of the main prod from overstressing. I think that same prod could have both longer draw length and higher efficiency if it was made with profile taper. I have made only two crossbow prods, so maybe Mr. Todeschini would comment on this.

Aleksei Sosnovski wrote

Quote:

Prod of the arbalest in the video seems to be rather inefficient. Seems to have neither distal nor profile taper, very wide at the ends. there seems to be another smaller "prod" that keeps center of the main prod from overstressing. I think that same prod could have both longer draw length and higher efficiency if it was made with profile taper.

Aleksei is quite correct, the prod shown is grossly inefficient, the majority of the bend is happening between the inner leaf insert and halfway along the limbs with the tips adding very little but weight and a longer draw. If this bow had half the width removed as a steady line from the inner leaf to the tips and the draw was extended a few inches to compensate for the slightly lower poundage that would result, the performance would be significantly improved.

As shown it has no taper in either direction and this is of course not the case with European bows, but the limb set up does in fact have something in common with both car leaf springs and Chinese repeating bows that make their limbs from stacks of spring leaves and so in this way introduce the distal taper that is required for efficiency. It is this inner leaf on the youtube bow that is in fact adding a little taper to the set up. For whatever reason western makers did not do this.

There are of course pros and cons to leaf stacks like this. The good points are that the springs are easier to make and can be bent much more before they hit their yield points as the sections are thinner so you can produce a longer power stroke for a given bow width and in cross bows power stroke is massively important as the distances are always relatively short. With almost no skill, it is possible to bandsaw up a stack of ash lathes 1/4" (6mm) thick, stack them up like a leaf spring on a car and make a 100lb bow. The down side is that the leaves lose efficiency in friction and in the actual interactions of the leaves in some physics way I don't have the maths or logic to fully explain. The bottom line is that it still works well and I would not be at all suprised if the inefficiencies are not out weighed by the advantage of a longer stroke.

Single piece bows are limited by their yield points far sooner than a thin leafed stack and so a thinner bow of a given width can draw far more than a thicker bow of the same width. As an example a 15mm thick bow of 700mm width will be limited to about 165mm of draw before it starts to get mighty close to the yield point. So to answer Jeans question, they were limited to the length by their choice of the width and thickness of the bow. I suspect that if you could make a steel multi leaf bow at 700mm that could draw 9 or 10" so, about 250mm and this would out perform a single leaf bow for a given power at say about 800lb; they just didn't do it either because I am wrong or they never thought of it or just didn't do it for some reason.

The last aspect is that you need faith. Faith in a bow that is not going to snap on you and I would rather shoot a lazy bow than one that is close to the yield. My bows are tempered to bend not snap and I run them either a little under or significantly under the yield (depending on weight) , but this is done in a very controlled way and I know this is the case. Historically this level of accuracy was not possible and if you get to the yield point and you find that it is too brittle the consequences could be fatal, so you run the bow on a shorter draw than you could, just to be safe.

I made a repro earlier this year of a hunting bow that was owned by Maximillian and that was very notable in that it had a fairly standard bow width of about 600mm (2' ) but a draw of 170mm (7") about 1.5" 40mm more than you would expect and I can only guess that this was made by very skilled people, shot many many times before it was handed over and probably inspected regularly. The result however would have been a bow that was shooting with maybe 30-35% more energy delivery for the given draw weight.

Everything is compromise .....................

Regards


Tod

As for the Knight and the Blast Furnace stats, I have been handling it for the past year from interlibrary loan and while the majority of non-italian armour was iron until the late 15th (circa 1480 or so), the Italians also had a large export business, and either Tomasco or Antonio Missaglia had to send people to spain to collect debts owed them for armour. So while iron armour outside of italy would be the norm there would also be access to steel from either good local makers or imports. By the late 15th though the amount of steel available seems to increase dramatically.\

EDIT: Of the 22 pieces of fourteenth century ‘German’ armour (they are northern european pieces of armour, Williams couldn't be positive exactly where they were from) tested by Williams only half are made of steel, and only a few of them were tempered in any way. KATBF 331-332

There are also the multi prod crossbows using 2 or 3 prods linked together to shoot one bolt ( Not to be confused with a multi prod weapons shooting more than one projectile ): These seem to have used very long bolts and long power strokes.

Discussed here: http://www.myArmoury.com/talk/viewtopic.php?t...highlight=

So there are different ways to get around the materials stress limits making short draw lengths a needed safety factor.

Off course if we limit ourselves to European crossbows these work arounds are not useful to making historically accurate reproductions, but it's interesting as a separate purely design issue ( Curiosity ).

Modern crossbows not only use better and more uniform quality materials to get longer power strokes but also the modern pulley systems also used in modern compound bows:
http://en.wikipedia.org/wiki/Crossbow

The video clearly demonstrates the viability of a heavier bolt, as Jean stated. In all the material I've read and all the discussions I've had online, Tod's stats for the appropriate weight of a bolt is one of the lowest estimates I've seen.

The leaf-spring prod is of course very inefficient, it's designed to provide suspension for a minivan not to shoot bolts, and I think this actually offsets the longer stroke at least somewhat. Though this is nowhere near anything like a serious experiment and there are so many variables it is tricky to make definitive conclusions, but clearly that is a heavier bolt than the one Tod used in his initial tests, and though the bolt itself is also obviously crude and very inefficient (in shape, in the fins or vanes) compared to period designs, it's efficient enough to perform relatively well, better tha most other similar experiments I've seen.

My best information (including from Alan Williams book and from some data I've seen from Royal Armouries and the Lubeck Symposium) are that 1200 lb draw was more likely to be the mean for power of an historical weapon, not 800, so this is another area where Tod and I disagree. With all due respect to his considerable skills, I don't think he has yet equalled let alone surpassed the abilities of the artisans who were making these devices as military weapons so I'm not sure I follow his logic about thickness being the limitation he believes it to be. But that is just speculation and opinion on my part at this point, I hope to soon have some more solid data to back it up.

In my current opinion the power of this weapon in the video is actually significantly less than a much smaller windlass arbalest from the 15th or 16th Century or even a very small cranequin arbalest such as were used by mounted marksmen from the 15th Century and by hunters into the 17th and 18th Century.

Finally I'm also not sure I agree about the reason for the increasingly short power-stroke. There were weapons in-period with quite a range of stroke length actually, I think the reasons were more complex.

But I'll keep looking, I have some things in the pipeline which may be coming out early next year. I should finally have some solid numbers from antique bolts, and prod strengths from antique weapons at the very least. Hopefully a couple of other nice surprises.

J

Jean Henri Chandler wrote

Quote:

Tod's stats for the appropriate weight of a bolt is one of the lowest estimates I've seen.

I took these from a few bolts in the Netherlands Royal Armouries book as one of the few sources with a weight.

Quote:

My best information (including from Alan Williams book and from some data I've seen from Royal Armouries and the Lubeck Symposium) are that 1200 lb draw was more likely to be the mean for power of an historical weapon, not 800, so this is another area where Tod and I disagree. With all due respect to his considerable skills, I don't think he has yet equalled let alone surpassed the abilities of the artisans who were making these devices as military weapons so I'm not sure I follow his logic about thickness being the limitation he believes it to be.

a bow thickness of 50mm x 15mm x 700 at 6.5" draws 850lb and only a little beyond this it will hit the yield. Period windlass bows of European manufacture are generally at about this size except that thickness can go up to 18-19mm and up at this point the weight will be very significantly higher than that for 15mm, so I could see 1200 being not that unusual, but many are at the 14,15, 16 point. I am not sure I said that 800 was normal for a war bow, I would personally say that would be the least required for a windlass war bow but I am frankly still rather scared of making anything bigger at present, but it will come.

As for equalling the skills of previous makers? I am no where near it. I have made a few dozen bows and have not had an apprenticeship and by the time I get to the end of my life perhaps I can but certainly not for a couple of decades if ever. There are so many aspects that I struggle to fully understand as these are deceptively complicated things - part of the reason I love making them.

And I would love to see some more real data as this is in very short supply so please press on!

Regards

Tod

I think we are in agreement, and I applaud your efforts as I'm sure you know. Hopefully more data will come to light.

Regarding your ratios of thickness and dimensions to draw weight, would that not also depend on the specific temper of the steel, how stiff / springy it was? Maybe that is one of the elusive factors. Certainly period forging techniques and, I know this is somewhat controversial but I suspect period metalurgy and steel were better for making swords than modern steels, which are ideal for making i-beams, rebar, washing machines etc. Maybe there are similar factors at work with crossbow prods.

Do you forge the shape of your prods or do you use stock reduction?

Also... I totally understand your concern about testing stronger prods. It could be very dangerous. I wonder what kind of testing-rig Royal Armouries used...

J

let me clarify my question for Tod. Doesn't the quality of the steel and the heat treatment affect the yield point to thickness ratio?

J

Jean Henri Chandler wrote [quote]Regarding your ratios of thickness and dimensions to draw weight, would that not also depend on the specific temper of the steel, how stiff / springy it was? Maybe that is one of the elusive factors. Certainly period forging techniques and, I know this is somewhat controversial but I suspect period metalurgy and steel were better for making swords than modern steels, which are ideal for making i-beams, rebar, washing machines etc. Maybe there are similar factors at work with crossbow prods.

Do you forge the shape of your prods or do you use stock reduction?

[/quote

Steel make up is of course is a massive part of all this and I must say up front that there will be many others who know far more than me, but my understanding of this is as follows.

I suspect that forging techniques are not so much part of it as the steel and the temper. The steel I use is an old British steel grade called EN45 which is a standard spring steel of about .7% and is a tough spring steel of an unsophisticated alloying that is used for car leaf springs and so forth. I suspect it is not that different to a basic spring steel of the times, but only a spark test will show exactly what the old ones were made of. However maybe its performance is a few percent different to the originals - lets get back to this. So the performance should not be that different.

This is totally counter intuitive, but the stiffness of the material is not dependant on temper, but the yield point changes and the mode of failure will alter. So take a piece of steel and quench full hard, it will be as stiff as a piece that is normalised, but it is the yield point that will alter and whether it fractures catastrophically or deforms. Too hard and the bow will snap at quite a short draw; too soft and the bow will deform before it gets to full draw, just right and the bow will bend reliably to full draw, and this draw will be more than either too hard or too soft. So historically what you try to do is hit a temper temperature/hardness that allows you a bend that is as large as possible without either breaking catastrophically or bending. What this means is that (historically) to be safe you make sure that the bend keeps well below the yield point as you are not quite sure of which the result may be if you exceed the yield.

I know what the steel is and what its performance stats are at different hardnesses, and the bows are carefully heat treated so the performance is predicatably known, however being cautious of a lawsuit, the bows are tempered soft, so they will bend rather than break. This means that they will not draw much more than I set them up for before they bend, however the stiffness and therefore the return rate will be the same as if they were tempered harder.

So the temper of a specific steel does not change its stiffness, however which steel is used will effect the stiffness, and although Jean suspects our medieval contemporaries were very good at steel working, and I agree, however I suspect their steels for this application were not that much better than ours, if at all, so I think other things were going on.

As Jean alluded to earlier in this thread

Quote:

I don't think he has yet equalled let alone surpassed the abilities of the artisans who were making these devices as military weapons

I depressingly have to agree with Jean on this point; I like to think I make good bows and I am one of the very few trying to make historically representative bows, but there is always room for improvement. What this means is that 10% improvement here and 10% there and with a few of these you get a lot of % improvement. So if the steel is down slightly on performance (which it may or may not be) this is not critical, but as part of a system it can add up. As I said before, I love bows simply because they have so many aspects that are taxing. Well it now looks like I have 3 of these heavier bow to make in the next few months so there is an upcoming opportunity to find out some things.

I do not make the steels myself, but have them made for me. The bows are milled to profile and the tips forged, ensuring an even profile on each limb.

Regards

Tod

thanks Todd, that is very interesting. Who knows maybe this thread is helping to generate some crossbow business ? :) I have a feeling interest in them is increasing generally.

Please keep us in the loop as your new weapons are made and tested.

J