Didnt know that was you here under a diff handle! After coming across it the other day I wanted to write you and thank you for doing the wiki stuff.
I sent Ivo a video of an earlier manuballista build that was getting 175fps with about 50lbs pull on a scorpyd platform. If you'd like to see it I'd be happy to send you a vid. I just finished a new ballista build with a new arm length to axle to axle ratio.
On my blog somewhere I believe I still might have math calculations concerning limbtip speed to string speed you might find interesting as it might help any theories you have.
Im still out on a limb with my crazy ratio's and even Nick is skeptical. So now my design allows one to use either a compounding or non compounding design with one simple quick change of string attachement points. Takes about ten or twenty seconds. It automatically doubles the available power by eliminating the mech advantage the pulley system provides, while the still remain in place.
I've also made it so one can adjust the mech advantage in increments from zero to a two to one mech. advantage such as the Woodland Survival Flipper employs.
How is your book coming along? I hope to write one someday and share my performance findings. Chiefly Nick has been the only one using some of my ideas and findings.
My newest build with really short arms might give him a nudge, but I will first have to prove it. So, I have a bevy of custom arrows weighing in from 244 grains all the way up to 1280.
I have stopped contributing to RAT as my work is not so popular there LOL.
While I have mathematics and mathematians sometimes helpful in design verification, they are loathe to accept new theory or evidence if the math does not agree.
The benefit of results driven work is that the performance is duplicatable upon demand. Chronies dont lie!
BTW - thanks for the wiki link to my blog. Its an honor to be included with Nicks work and machine. With the new arm positioning, we believe the new and proposed design to be the most accurate interpretation of the Orsova find but is yet to be verified by testing and the chrony!
If you read the comments there, I post as Captn Harpoon a lot. I took the nickname as I was trying to convince Nick to up the bolt weight, size and length from 2800 grain durabolts to 7500 - 10,000
He said they werent arrows and accused me of being part of a japanese whaling fleet haha.
With any luck Firefly will soon be tossing around 20,000 grains, or something about four to five feet long. I believe Firefly is up to the job and the weight more to her liking.
If nicks machine resembles my designs or my machines resemble nicks machine its because we share the same tech. to a certain degree. I am unsure of nicks reluctance to finish up the new arms, so he is due for a video of my new build and performance.
He is a hard fella to convince and I have to work within the confines of his build guidelines, namely period correct technology wise and correct to the Orsova frame find.
Please check out the Wiki I founded mostly for my own manuballista (in Greek cheiroballistra) project:
Currently all of the content in that Wiki is written by me, but I'm hoping that'll change eventually. Unfortunately the lack of any decent communication channels (e.g. proper forums or mailing lists) within the Wiki project makes collaboration very difficult. I may end up moving the Wiki to another host just because of this.
You are probably most interested in these articles, which I hope will eventually end up into "real" articles in scientific publications:
The problem I've noted with academic research related to the manuballista (and ancient artillery in general) is that the academics tend to be, well, academics, meaning they're fluent in ancient Greek and Latin, but lack experience in practical issues. For example, their reconstructions may be perfectly doable with modern machinery, but not with tools of the era (antiquity). This tends to lead to unrealistic reconstructions. Second thing thing the academics seem to struggle with is performance of these machines, which is so poor that nobody in the antiquity would have used them. Anyways, I'm hoping that my work as an academic and
as a craftsman/hobbyist will eventually help fill the voids I've described.
Now, fortunately some non-academics have managed to get impressive results from these machines:
Actually Nick's blog was the reason I again (after a pause) became interested of the torsion weapons. As an example, his machine has spit out war-weight bolts at 400fps.
As you can see, I'm pretty deep in this manuballista stuff, so feel free to ask anything