Hi everyone. I should have gotten this more along before posting, but I'm excited about it, and wanted you to see it, even though it has a long ways to go.
This is the spring frame and the stock for a small torsion spring arrow firing machine. What you are seeing is the spring frame, made of ash, and the stock. A slider will fit into the dovetail groove in the stock, and the four holes in the spring frame are going to have rope (I hope to make them sinew) springs. Two bow arms will be fitted into the springs, and the machine is spanned (drawn) back by leaning on a stomach rest that will be at the end of the stock, thereby pulling the slider back until I lock it with a bronze and iron trigger.
Part of this project is making bronze components. I have a bronze melting oven in progress, propane fired and capable of melting bronze at 2400 degrees (more or less, depending on the exact alloy used). The oven is small, and will weigh about 90 lbs. This manuballista will need a number of bronze plates for the top, sides, and front of the frame, and a few components of iron as welll.
You have to use a bit of imagination here. The stock will be much lower, but I just fitted it in the frame to give an idea of what it will look like what it is done. Also, the frame is only rough sanded, and the stock is only very rough planed so far.
As for how powerful this machine is going to be, I have no idea. We do know that one charactaristic of arrow firing machines is the very flat, fast trajectory, so it should make a bolt move very fast. And many factors go into these machines, such as moisture in the air, how much you crank torsion into the springs, etc. I can't recall anyone today making reconstructed seige engines using sinew or hair ropes. I want to make the rope springs from this from sinew, probably more expensive than I want, and difficult, but after this much work (I can't tell you how much time I put into it. Lots! Just learning to make mortise and tenion joints has been a journey). I also have to find a blacksmith to make hand forged iron nails for fitting the plates to the frame. The diameter of the springs will be 1 3/8", or possible a bit more, depending on how the spring washers come out. The bolts for this will be about 12.5" (my notes and drawings are in the shop in my now pretty worn "Boys Big Book of Machines of Death"). I will put this machine through all kinds of tests, chronograph, armor piercing, flight shooting, etc. and under field conditions (well, as close as I can come up with, in kit, with armor, after road marches, different weather conditions, etc).
I think it will be many months before I can actually show the finished weapon here, and will when I can. I probably should have waited, but hey, this place is about sharing.
Dane
PS Here is a link to an article with a photo of a reconstructed manuballista. Mine will be similar to this, but not exact for various reasons.
http://www.romanhideout.com/news/2005/20050224.asp[attachment deleted by admin]
