Warhammer, you are probably a nice guy, and sincere, but you have to understand my perspective, which will not change in the case of Roman and Greek torsion and tension engineering. The whole point of researching the machines and building working interpretations of a Vitruvious or Heron machine is this: to understand the probable capabilities and performance of ancient artillery. Not what they may do if you reengineer them, but what a Roman army in 79 AD would have had as way of field artillery available in the then-here and now.
What you are doing, while it is important for you to break new ground, is contrary to what some of us are doing. An example would be to explore a medieval English yew war bow, but make it out of fiberglass, and replace clothyard arrows with fiber arrows. What do you gain? More performance than is possible with a 14th century bow, but if you are trying to understand what actual medieval bows could do, you learn nothing of historical value.
Another is to take a rifled musket reproduction from the US Civil War, glass bed the barrel, rework the trigger, replace the sights, and optimize the weapons in every other way possible. You have a much more accurate weapons than a soldier of 1863 would have had, but you don’t learn much about the accuracy and shooting characteristics of an actual weapon from that conflict.
The outswinger vs. inswinger battles – I agree with how much more effective inswingers are, and probably were much more prevalent in the ancient world than some think they were. Hartra had to be an inswinger, and it appears to be thus via Trajan’s column. Perhaps even all stone throwing machines in mid empire were inswingers. My own little machines are based on earlier machines, and I think outswinging configuration is fair and was probably the primary ways of setting up a scorpion. If I were to build a metal framed arrow machine, it would be most definitely an inswinger.
Purely improving performance of an ancient design is fine if that floats your boat, but the chances of Roman and Greek engineers having developed compound (wheels) technology is bordering on ridiculous (Kind of like SCA folks using duct tape and saying if they had it in the 14th century, they would have used it as way of justification). What you are doing is not engineering interpretations of ancient stone and arrow throwing machines, but something entirely different. I’m not really sure what the entire point of that is, as catapults and ballistas have been obsolete weapons systems for almost 2,000 years. Da Vinci did some fanciful sketches of theoretical war machines at a time when gun powder had doomed such weapons. Hence, they never got beyond design sketches.
Maybe you should focus on the pumpkin chuckers. Those guys are pushing catapult designs to the max, and you would feel right at home. The goal is to hurl a pumpkin 1 mile. I think they would welcome you with open arms. Google them, as there is tons of stuff online about what they do, videos, etc. Googling Team Tormenta will get you right to their site, if I recall. Nice group of folks, too.
Dane