Typical dimensions of late Gothic composite bows

Hi guys, my long term project has reached the point where I am ready to build a composite prod. There is too much info out there (ironically) so I need to narrow things down. Any idea on the typical dimensions of a sporting crossbow composite prod of the late 15th century Germanic/saxon/tyroll region, otherwise known as a late Gothic style? Particularly, the thickness at centre??
Thanks in advance
Andrew

I don't have the figures for that, but can recommend you look at Holger Richter's "Die Hornbogen Armbrust" pub. by Verlag Angelika Hornig, 2006.
It's all in German, but there are chapter precis in English.  Includes a summary of composite crossbow prod construction from a builder in England. 
Have fun stormin' the castle.  Geezer

Composite bows or prods are some of the most complex constructions on the planet.  You've got to have the right core wood -- most substitutes won't work.  Then you've got to have good horn (not antler) -- cowhorn does not work very well, water buffalo horn works the best.  Then there's the sinew -- finding long sinew is not simple; pounding it out is really labor intensive (or expensive, degreasing it, combing it into bundles is the easy part.  Lastly you've got to learn how to make and apply fish glues, sinew glues and hide glues.  No substitutes allowed or you waste lots of time and money.  Commercial hide glue is pretty worthless. 

If you haven't studied and practiced these skills, I seriously suggest you spend some time on the Asian Traditional Archery Network site:  www.atarn.net  and the Farcebook page for the group as well.  I'm one of the moderators of the main group.

Hi Kenh, that's why I disappeared this long while, I've been hiding out with the guys on Primitive Archer specifically to learn all that stuff. Nearly there. Now I need the accurate dimensions because, as you know, a tiny error in size translates to a huge difference in bow strength. Incidentally, I was planning on following the type that does not use a wood core, the solid glue-lam buffalo horn beam with sinew cap wrapped all the way around and birch bark cover.

A horn-only bow will take a wicked set and be pretty useless pretty quick.  If horn has nothing to resist the tension from the string, it will set, and there goes your power...

Best of luck.

Oh. I Was going by the cross-sections and drawings I have been able to source, the ones that show timber as part of the construction show it as the bottom layer, not a true core layer in the way an Asiatic bow would recognise it. I haven't found a single drawing or section of horn/maple /sinew although all my instincts scream that is the most efficient construction method. Can you point me anywhere?

The German book that Geezer mentioned above -- Die Hornbogen Armbrust is probably your best source.  I haven't read it, but I understand it's the equivalent of Adam Karpowicz' book on Ottoman Turkish bows -- the definitive work on "horn bows".  The German title translates as The Hornbow Crossbow.  Using Google Translate should make translation relatively easy...

One of the European crossbow guys sent me a copy of Die Armbrust (much appreciated!), the English summary is very helpful. Also finally got around to ordering a copy of Casson's manuscript.   Casson's bow clearly has a wood core, as do several other bows analysed in DA, though the English summary states they are of oak; think I'll use hornbeam or maple.

Good deal!  Best of luck in your build!

the old composite crossbow bows weren't the same as the turkish bow. the sections I've seen till now show me that they didn't exactly know what they do (more experiental) when the turkish bow are very logical with horn on compression side, wood on neutral axe and sinew on tension side...
European crossbow were more experiental and also the horns in european animals aren't as big as water buffalo, so they have to glue a lot of small horn plates together to create a general shape make of horn.

I literally can't get to the paper at the moment but de Casson quotes two different requisitions by a crossbow maker working in fourteenth century France (I think) totalling 50 yew staves and 50 large sheep horns showing ibex was the preferred horn for superior bows and that they used a yew core or box at that time and location.

Robert l'Artilleeur commission for Rouen castle 1358 and 1361 but it was 12 rams horns with 4lbs of ox sinew shredded like lint and 4lbs of glue. It seems there were enough off-cuts from the horns to make the last bow. The list was the same for each set of 25 bows. source Archives Nationales, Monuments Historiches, K48 No 12. Cited by Baron de Cosson, Archaeologia 1893.

The crossbow sections I've seen till now where all very different as if they were experimenting or just every bow maker has his own method...
Here a bow with small horn plates glued on belly and a very thin layer of sinew on back.
But I've already seen pictures of bow with wood on belly and horn at the center (illogical) ...

If you have other information about medieval horn prod, I'm interested.
I've made a little horn bow (80lbs) for a small crossbow, but I'd like to try another and stronger one

Interesting topic  : http://www.primitivearcher.com/smf/index.php?topic=60686.0

OK, so, this is my summary, there are two types, the all-horn core and the wood and horn core.  The all horn can be split into cores using two layers, which I suspect are made of off-cuts, and cores of single layers. The horn and wood cores might be earlier or a more north/west type, the all-horn may be a more central European type??? Ibex is the preferred horn but baleen is better. Wood cores usually identified as oak are almost certainly yew.
Horn and wood cores use yew in the centre having chased a ring and tapered the lath as in every self-bow, the sinew laid over the curve of the ring in a way every bowyer recognises in a minimum of 3 layers. The belly lath is really convenient for tillering as it tapers like the belly of a self bow and can be scraped for a sweet curve in a way that horn isn't. The two timber layers sandwich a tapering horn bar forming a box girder type thing but the bottom layer is slightly wider than the horn to receive the sinew. 
Now, the ends of the prods are held together by a 4.5" horn wedge with a knob on the end, which goes right through the box beam and sinew and is itself reinforced by three horn wedges forming a reinforcing second layer at the tips. The knobs are carved for the nocks and covered in pitch

Thanks for interesting information. you have red in a book? Can I know which one? I'm interested to know more even if I'm not so good in English to read a whole book. Is it the french archives on your last message (in french that's easier for me !)
Or if you have PDF or websites...

You want to make a replica of an old horn prod?

Die Hornbogen Armbrust is good for pictures but you really need to read German to get the most from it.
The classic thread of medieval crossbows and their accoutrements  section http://www.vikingsword.com/vb/showthread.php?t=7516  has pages and pages of eye-candy.
Baron de Cassons's manuscript is essential to read the last four pages called notes on hornbow construction. It also has the full list of items needed by Robert l'Artilleeur in French and English which de Casson found in the French archives.

"The Crossbow of Ulrich V. Count of Wurtemburg, 1460, with remarks on it's construction" Baron de Cosson, Archaeologia 1893

Yes, I hope to start building this Spring. Any advice?

Yes, I know some of the link you speak about... Oh, not sure I can advice you. I'm new to crossbow making. I'm more a bowyer of selfbows I've only tried composite bows 3 times (chinese bow, and turkish) but when I see how big are the crossbow prods, that's very very different. The draw length is very short, but this must be at least 300-400 lbs with such big bows.
I've made a chinese bow of 80lbs (32'' draw) and it's only 1.5-1.7 cm thick... here that's bigger for a shorter bow.

Yes, selfbows are my main interest, I am working on a lightweight Magyar at the moment. The thick crossbow prods for sport use seem to be between 400 and 600 pounds, and double that for wall mounted war bows

Wishing you luck, and I hope you'll keep sharing your build here on the forum. I've not made a hornbow yet, but have made some decent wood/sinew prods, most recently a 200# model of osage orange. Eventually, I'd like to work my way up to a proper horn/sinew prod.

that's an interesting project to make an old technic horn crossbow prod. I hope you'll succeed. and if you make bows, you certainly know that you learn more from bows you break than the one that works!
the problem with horn bows is that if you make it as a test, that's very time consuming and money consuming too as horns are generally expensive (less if you use horn plates like medieval ones).

here the bows I make : http://www.licorneargent.be/photos/nos-arcs/nos-longbows/

And the making of the chinese bow I've made (except I haven't finished this article yet) : http://www.licorneargent.be/les-arcs/facture-experience/fabrication-arc-composite/
(about 100 hours to make it)

Cost is the reason for copying the bow in de Cosson's paper as it's a plan of a working, long-lived bow, also I will use water buffalo horn side-walls as these off-cuts are much less expensive than the back-strips used in selfbows.

Horns are expensive when they are long (and so very rare). this can go to 80-100 euros for one 75cm horn, 50euros for 50cm, 25euros for 35cm... so for crossbows, that's less expensive than bows. and if you choose horn plates, you can find better price...
but the less expensive is artificial horn !

Artificial horn just does not work in wood-horn-sinew composites, any more than artificial sinew does.

A mega box of offcuts (10kg) is the best way to go. Horn plates may have been heavily heat treated and pressed flat, they can be brittle and snap when you bend them.