Composite Bows

I am setting a saga on the Iberian Peninsula, mid-12th century. Due to the large Muslim influence in the area, composite bows are definitely available.

Now comes the trick -- how to map them?

I know, I know, this is asking for all sorts of trouble, all sorts of partisanship on the topic, but does anyone have any useful information or websites that might help me understand the differences between a standard European shortbow and the types of composite bows available in Iberia? Is it a difference in range, power, ease of use, expense?

Any ideas would be appreciated. :slight_smile:

I'll try to tell you what I know. I can't cite any sources for you, this is stuff I picked up over the years. I learned quite a bit from some documentaries on the History Channel a few years back...

Every bow is essentially a big spring. The efficiency of that spring - its ability to store energy from the archer's draw and deliver it to the arrow - is what makes one bow better than another. If you have ever had the misfortune to shoot a warped bow then you'll know the whole bow vibrates with a loud "twang." That means some of the archer's energy is going into vibrational energy, not kinetic energy imparted to the arrow. That's bad.

If I recall correctly, European bows through the Renaissance all had a round cross-section like a staff. Modern wooden bows have a rectangular or diamond cross-section which for some reason is more efficient. No one had thought of that in the Middle Ages. This is an important point because medieval bows had less punch for their draw weight than do modern bows, even leaving out such modern improvements as fiberglass and pulley/cam systems (compound bows).

The short bow or self bow is basically just a round, tapered staff with a string. It's made out of some flexible wood which makes it rather springy. It's a fairly good weapon, and the easiest bow to make.

The long bow is always made out of yew wood. The staff is cut from near the middle of the tree so half of it is made of dense, stiff heart wood and the other half is light, springy sap wood. The dense wood is the part facing the archer. The dense wood resists being compressed and the springy wood wants to stretch back to its original shape. A properly cut yew staff is an efficient natural spring. It is more efficient than a standard bow and therefore is a better weapon.

A composite bow uses the same principle but instead of a naturally-occurring spring the bowyer makes an artificial one. The belly of the bow (facing the archer) may be made of wood or horn and the back is usually made of sinew laminated together with glue. My opinion is that this is a better spring than the yew-wood long bow. However, the proper manufacture of such a bow takes months or years, as multiple layers have to be carefully laminated, then thoroughly dried, with no cracking or separation. The glue used in the lamination is water-soluble so the whole thing is usually coated with resin and/or fish skin for waterproofing.

For a bow of the same size, I think a composite bow should at least equal the power of a long bow. However, composite bows historically were nowhere near the size of a long bow. In fact they were generally shorter than "short" bows. Composite bows were typically small enough that they could be fired from horseback, not something I would want to try with a European short bow let alone a longbow.

So if I were making composite bow stats for my own Saga, I would make them Expensive (since they take so long to make) and give them stats somewhere between a short bow and a long bow. And a Load lower than either.


-Sir Garlon

Nice Description.

On another note, if we wanted to create a magical bow with bolt , which Fo/Te would be possible?

CrIg Bow of fire vengence;
CrHe Perfect bow of the serf;
CrVi Pure bow of light againt demons;

I'm having troubles dealing with these issues:

1- Requisites
2- Aiming
3- Base levels
4- Ranges



William's Bow - modelled on Blade of Virulent Flames

Arrow of Fiery Vengeance CrIg 15
Sheathes an arrow-head, fired from the bow as the command word is spoken, with flames. This doubles the weapon damage for the arrow (depending upon the type of bow used), or +5 - whichever is greater.
[B: 5, R: Touch +1, D: Diameter +1, T: Individual]
Uses: x24 (+5)

Effect total: 20

I don't really understand what the 'Perfect Bow of the Serf' or 'Bow of Light against Demons' is intended to do ... so, it's difficult to suggest solutions here.

Actually this is a great question and leads to one of my own.

Drawing inspiration for the History channel, I can imagine useing magic to create natural items that are simply structurally superior to items that exist during the middle ages.

That is one could make a bow out of wood that is stronger than normal wood. This wood could be bent more without breaking. Again, a string could be made with magic that is structurally stronger than the string that could be made at that this time.

Essentially one could build a better bow and shoot an arrow without using magic. This arrow would then have more force and do more damage.

The same design could be done to catapults or a variety of other seize weapons. Natural momentum is maintained, but superior material is used. Such designs seem legal, but also problematic as they could unbalance the game.

Did you have some specific balance issue in mind?

Actually I don't. Two seperate things came together in my mind.

As you've reminded me in the past, in Ars Magica objects in motion by magic remain in motion by magic. This causes those objects to stop short of a magus or covenant when the contact the Parma Magica or Aegis of the Hearth.

With this in mind, I was watching a show on trebuchets and I realized it could be easy for someone to build a device tht uses natural motion, but the device itself is aided by magic. This could allow for the weapon to possess more force than it would normally have. Items thrown would have natural motion and could ignore Parma Magia or Aegis of the Hearth.

I have no actual plans to use this idea in my games, but it seems like an area munckins could exploit. I suppose I was just rambling out :wink: loud :wink:


You mean, spells like these?

Wood of Steel Ritual, MuHe(Te) 25.

Base : 4 Change a plant/plant product into metal or stone (Te Req)

R: Touch (+1)
D: Mom. (+0)
T: Structure (+4)

Req: Terram (free)

Gives wood the strength of steel.

Or perhaps...
Weight of Lead MuTe25 (casting requisites)

Base : 4 Change one property of a material, from gold & gems down to dirt (Requisites required for actual material)

R: Voice (+2)
D: Diameter (+1)
T:Indvidual (+2 for Large masses)

Requisites : (appropriate for the form of the target)

Makes one inanimate object weigh as much as an equivalent amount of Lead, for about 2 minutes. (Lead weighs in at a whopping 11.34 metric tons per cubic meter, or 839 lbs per cubic foot. One cubic pace of lead would weigh 22, 631 lbs). A cloak turned to lead would probably crush somone.

Both of these would enhance our medieval trebuchet, which relies on the mass of the counterbalance to do it's work...Or make the projectile more massive as it begins it's downward fall...


Hey Steve,

Yes. Exactly. These items circumvent the moved by magic issue and allow mundane items to move with great natural force.

On reflection, we should keep these ideas to ourself rather than detail them because I'm sure we've encouraged a munkin somewhere. Oh well.

The composite bow is considerably more powerful then the "standard" short bow. It also requires more strength to use and is far more expensive to construct.

The longbow though likely generates an arrow moving at higher velocity as it leaves the string, this gives it more punch and longer ranger. The physics behind this is fairly simple...a first year text would have the formulas to model most of this. What I don't know is how to directly compare the pull weights on the bows, but I suspect the short bow is likely the lower of the two...and so the launch velocity will be lower...and even if it is not the launch velocity will be down because that is a function of distance and time and the shorter bow means the force falls off quicker anyway.

Force of spring: -kx where k is a constant and x is the distance from equilibrium.
Velocity arrow leaves string at: sqrt(2
da) where d is distance arrow travels before leaving string, and a is the acceleration on the arrow
acceleration is: m/F = m/(-k

However as x is constantly changing, hence a is constantly changing you need to integrate or make some simplifying assumptions. However if you can find out the normal length of a longbow arrow, and the normal length of a shortbow arrow and the draw weights of both you can see a great deal. And for Ars all you need is an estimate.

the velocity the arrow has at launch gives the range of the arrow as it will loose that velocity as it travels, and it gives the momentum transfer which is its penetration power. Depending on how fast the arrow looses velocity...a function of drag gives you the fall of armor penetration and leathality.

Anyway from a game point of view you should give it more damage then a short bow, and a slightly longer range but it should be inferior to the longbow...especially in range. It should also require at least 1 strength rating higher than the "standard" short bow.

As for changing wood to steel on a would render the bow useless since no human could draw it...arbelists (crossbows with steel bows) required a winch to crank back...a steel longbow would require the same thing. I'd be dubious of most other mechanical weapons as well...balista and onagers relied on twisted sinew/rope "springs" and a trebuche would not be improved (likely it would work less well) if you changed the wood into steel...the trebuche doesn't use a spring anyway. A catapult would likely come appart as the force required to bend a steel beam would exceed the forces holding the structure together.

The fact of the matter is that those weapons worked very well and there is not much modern materials can do to improve on them, besides making them less prone to wearing out. The auto balista worked so well the greeks decided to not use it...the first time I've heard of an effective weapon not being used because it was effective.

IIRC it was a Spartan king who was sufficiently impressed by the balista to forbid its use, whatever that was worth at the time.

After all, the crossbow worked so well, that Urban II banned its use against Christians already 1097. And the arbalest worked so well, that the Lateran Council of 1139 banned its use against Christians again. :wink:
Point here being, that the more often an order or a law is reissued and repeated, the more sceptical historians get about it being observed.

I also recall the mention of steel bows as equipment of Byzantine archers in Robert Graves' novel 'Count Belisarius'. This is not a proof of their existence, of course, despite Graves' reputation as an historian. But for a thorough research on Byzantine bows I lack the time for now.

In any case, you are right about transforming a wooden longbow to steel. This will make it completely unusable: with its circular crossection it would far rather break then bend.

Kind regards,


I imagine it would be possible to make a steel bow, not sure if the metalurgy of the byzantines would be up to it but its not something impossible for them to have done. I'm not sure exactly why they would do it since there is no obvious advantage to a steel bow compared to a well made composite.

My objection to the spells is mainly that such a bow would have to be very thin, while a normal bow is not, so once you convert the wood bow into steel (and then the question of exactly what sort of steel springs to mind) you would have a steel bow with such a thickness well that you could not bend it with less that a serious lever. Try to bend with your hands an 1/8" or 4 mm piece of steel some time, then try something like a 1/4" or 6 mm...the first you might be able to do the later well is dubious.

No problem. Said munchkin will be required to have a character with Artes Liberales and at least one craft with scores of 10 (or something like that) to allow all the calculations to be done correctly and the materials crafted to correct specifications. Otherwise the first use of the trebuchet (for example) will cause catastrophic failure with substantial damage potential as the excessive forces act in unexpected ways.

As a side issue I really enjoyed the KJ Parker (?) novels. The Fencer trilogy (sword, bow, armour) and now the start of the Engineer trilogy. Really in-depth background to production and use of various military paraphanalia from some really odd perspectives, all as part of easy to read mundane (not much (any?) magic) fantasy stories. For example, Devices and Desires, the first of the Engineer trilogy, has entire nations being destroyed outright and other major consequences that are direct descendents from a highly skilled mechanical engineer discovering that an extra quarter revolution on a screw in a ballista improved it's capabilities. Something like that anyway. And though it sounds incredible it was almost dryly logical in the step-by-step progression from cause to effect. Rather cool!


I love dry logical step by step to cool. thanx for the suggestions I'll look for them!

Those are treally amazing books! The detail in them is fantastic, but the characters just keep pulling me along when the technicalities get a bit intense.

And The Bow is ... unnerving...

The idea was that you have wood that is still wood, but is as strong as steel; Not stiff and rigid, but as flexible and light as wood, but capable of carrying the loads that a same size piece of steel could, and bending like would. This would be the same as a good piece of 20th century spring steel...

That way, the trebuchet in question could support the weight of it's 2 ton counter weight being turned into about 20 tons of lead without coming apart (I could do the math and provide data on 4" x 4" cross section mid carbon steel loads, but suffice to say it's a lot...)

A better version would be to make it MuTe, with casting requisites, and use it on all kinds of things, instead of just wood.

And there used to be a skill in Ars4 that handled the construction of Siege Equipment and it's use - Engineering. (Siege Engineers were much sought after, and many were employed by noble or royal patrons).


Was there a Engineering ability in 4th ed? Hmmm... Are you sure?
Anyway, in ArM5 you could call it Craft: or Profession: Engineer. Presto! Artes Liberales would probably be needed too, as previously mentioned.

Some of us actually like having a larger skill list.
Players don't always feel confident in hand-wavey SG decisions.
Sure they could put out an ME Skills Book (never happen obviously) ,
and give some depth to Companions , but one can dream. :cry:

Well the more skills (or abilities as they are in ArsM) you have, the more at a disadvantage you are in regards to "hand-wavey SG decisions" as I see it.
The ability list is quite comprehensive and should be able to be used for all needs. if you add abilities you only make it more expensive xp vise.

Yep, it was craft : engineering. Sorry for the confusion. Yes, he had Artes Liberales and Philosophiae, too. Along with Siege Weapons, Craft : Mason, Craft : Carpenter, and Craft : Architect. He was really good at knocking things down, but needed a little more work on the rebuilding things.