a different type of horn-bow

[stuckinthemud]

Hi Guys,
Del's latest project reminded me of my stalled 5-year project, a replica Saxon horn-and-sinew crossbow. Still got lots of questions I haven't been able to find the answers to, so, anyone know anything about composite crossbow prods, for instance, the power the original hunting/target cross-bows typically used to operate at? Also, I do spend time on one or two of the crossbow forums, but anyone got any good advice/links to composite prod designs?  I have read PG's book and Redhawk's blog posts on his build but that is pretty much all I have found that is relevant to this particular project. All I can do at the moment is extrapolate dimensions and materials off photos - not really a reliable data-set if you have no idea of the power of the original. As usual, any and all advice gratefully received.
In particular, the one thing that really baffles me is why these things seem to not use a wooden core, any ideas?

[mikekeswick]

Better to use a wooden core. Stick to standard construction methods. Without a core the 'bow' will be unstable.
The draw to length ratio of hornbows is around 1.5:1. Work out what power stroke you want and go from there.
you will have to make one, record the stats,see what it comes out at and then make another if you aren't happy with the weight etc of the first one.
No need to go over 30mm wide. Remember thicker is quicker!

[loefflerchuck]

The famous French crossbows from the time of Richard the Lionheart were made of many strips of horn joined side by side backed with lots of sinew.

[stuckinthemud]

All the medieval ones I know of are strips of horn with non-matching grooves glued into a solid laminate with a huge sinew layer and some also have a sinew wrap across the sides, some even sinewed over the belly, very few, if any, have a wood core.

[davidjw]

Here are some interesting construction variations in medieval crossbows you might enjoy.  In the schematic drawings blue is horn; red is wood; yellow is sinew; and orange is leather.

[mikekeswick]

All the medieval ones I know of are strips of horn with non-matching grooves glued into a solid laminate with a huge sinew layer and some also have a sinew wrap across the sides, some even sinewed over the belly, very few, if any, have a wood core.

Crack on then!

[stuckinthemud]

Thanks for the encouragement Mike, I really should just bite that bullet but, 😀😀 i am too old to know everything 😀 thanks for the images David, I did enjoy them, really useful, never seen anything like them; where are they taken from?
The bow I want to copy is the Ulrich bow here http://www.metmuseum.org/art/collection/search/21940 but the prod is probably not the original one, so, I have the freedom to make one to my specs, only I don't know what poundage a given size of composite prod will produce or even what the original may have put out. I don't even know what UK laws have to say on this issue.

[loefflerchuck]

Love this! thanks David. I've been thinking about using strips of leftover horn for something like this. Horn and sinew without wood makes sense when you think of going to the field with the crossbow strung and leaving it stressed until it's gotime. 

[stuckinthemud]

So could you use horn side wall strips or would that introduce stability problems?

[davidjw]

The images are from the book "Die Hornbogenarmbrust: Geschichte und Technik" by Holger Richter.  There has to be some good reason for the complicated constructions, though it escapes me.  Sure does seem like a lot of work, so I assume it's not for nothing.  Loefflerchuck, you may be on to something, these weren't exactly rapid fire weapons.  Perhaps stability issues are mitigated by only having a 6" draw?

[loefflerchuck]

This is a bucket list project for me. David, do you know how long the bow part of the crossbow was?

[davidjw]

They are around 55-70cm ntn, for the 'handarmbruste' (this is what the cross-sections are from), there is another category of larger 'wallarmbruste' that are around 90-150cm ntn, the book doesn't show any cross-sections for these, but they appear to be much flatter and wider limbed with more reflex as well.

[Bjoern Sofeit]

The images are from the book "Die Hornbogenarmbrust: Geschichte und Technik" by Holger Richter.  There has to be some good reason for the complicated constructions, though it escapes me.  Sure does seem like a lot of work, so I assume it's not for nothing.  Loefflerchuck, you may be on to something, these weren't exactly rapid fire weapons.  Perhaps stability issues are mitigated by only having a 6" draw?

There's a very good reason these have so many matching grooves on all sides. Repros of originals that Andreas Bichler did are in the 500-700# range, and the ones with windlasses can go alot higher. Anyone that tried matching grooves knows what a royal pain it is, so this is definitely NOT just for fun. You don't want something that heavy fail close to your face.

[davidjw]

Yes indeed structural integrity would be of the utmost importance, especially when it is so close to your face!  I was more referring to the complicated construction of having so many small strips in such wide ranging configurations, as oppose to using fewer larger strips in a simpler configuration. This is what I though seemed like a lot of work for some good reason unbeknownst to me.  Would it increase stability or stiffness?  Or even material limitation due to the type of horn available?  Interestingly, it seems the horn didn't seem to go across the length of the prod in many cases (see photo), perhaps this is an indication of smaller sized horns being used?

[kiwijim]

I found this in the Grey Goosewing by E.G.Heath. P. 299-300
In a document dated 1358 describing the materials supplied to Peter the Saracen, arbalist to the King of England.
To make 25 bows of composite construction the document lists 25 pieces of yew, 12 "rams horns" and 4lb of shredded ox sinew.
That could suggest that some of the earlier prods had wooden cores. It may also suggest that each prod had a belly of a single slat of rams horn (and maybe the 25th prod was made from select off cuts?)
BTW, Peter the Saracen was also the maker of the famous crossbow of Ulrich the V, Count of Wurtemburg