Something that I think is important to keep in mind is that we are not always sure what the crossbow was intended for. There are plenty of examples in literature of crossbows of a wide range of sizes and uses. Ralph de Nesle's inventory from 1302 shows a huge number of crossbows of various sizes, which would require their own equipment and bolts to be effective. Combined with variable types of bolts we have a complicated job of estimating what any remaining bolts, crossbows and spanning contraptions were for unless they were found together with a description (sometimes happens in inventories).

Leo,

You are not alone Tod. I am fairly lucky as I am family friends with a gent who teaches applies sciences at a University back home so I can run some of the questions I have by him but even then sometimes I get it wrong as it goes over my head.

I was supposed to be working on my thesis yesterday. Luckily I was able to reach more or less where I wanted to between posts but that must be a bit harder making weapons, armour and such between posts... Always helps to keep the wife happy!

I will be likely here till July as I have several conferences I am speaking at early summer.

I am going to make some calls and get some info on the weight and dimensions on the bolts that are exact as my mind is not always 100% accurate.


RPM

The "string speed" factor is a tough one for me. This is what really determines the "terminal velocity" or bleed off for smaller than suited projectiles. Of course a projectile cannot be launched any faster than the string moves.

Problem is not even modern bows specify "string speed". And if I'm thinking right, it's more a matter of acceleration than speed. I'm sure the formulas for calculating it would be rather simple, but the problem is what data to plug in.

And I'm sure it's not an exact number either - a crossbow best suited to maximize KE with a 2000 grain projectile might lose some velocity in compared to foot pounds applied witha 1500 grain one, and even more loss with a 1000 grain one.

I'm sure there is also a point where the projectile is too light and loses stability, or even where the projectile is not strong enough to handle the stresses of acceleration and is damaged.

On a side note, recurve bows have always interested me with the whole spring principle. After all, they are springs that want to "spring back further" than a normal bow.

One minor advantage is they usually have a lower brace number proportionate to the length of the bow than other bows, but this is minor.

My guess as a recurve is stressed further by having in essence a muvch higher draw weight for it's length, it gives the ability of say an 80 pound pull bow to draw to a 100 lb draw weight (no easier to draw, it would still draw as a 100 pound draw).

Of course, I though you can just make the 100 pound draw to begin with. But if the material are not there to make a bow that handles higher draw weights well (stiff or dense enough), it's a way to use less dense but springier materials to make a bow that is of higher pound draw then you could have making a standard bow.