I want to build a pair of pistol crossbows, but I want them to be powerful and at least decently accurate. I've read that, generally, pistol crossbows are neither. I have little to no idea what I'm doing, and some help would be nice
I've done a few calculations and determined that a prod with 120 lbs. draw strength exerts a tension force of 533.76 Newtons. I want my bows to each have a crank that automatically cocks the string after only one turn. At 533.76 Newtons of force, and with a draw length of one foot, and an average torque exerted by my arm of 220 Newtons (50 pounds), the ideal radius of the crank would be 29.1 inches. That ain't a very good radius. Obviously, this isn't really feasible, but with 7 turns (not TOO terrible), I could decrease the radius to ~4.2 inches. One of the problems I've run into is where exactly to stick the 8-inch crank on a hand crossbow that likely won't surpass 24 inches in length.
Another issue is the material I should make it from. Carbon fiber is lightweight and more durable (I think, though I might be wrong) than wood. It's also pretty freakin' pricey. And difficult to work with. As an alternative to carbon fiber, what kind of wood, do you think, would be best to work with? I'd prefer a lightweight but strong wood that looks moderately presentable.
What material should the prod be made from? I've read that spring steel can endure a lot of stress and is fairly cheap and available. Not quite sure what to use. I'd like a recurve prod that's strong (100+ lbs.), durable, and doesn't look awful.
So these are the main problems I've run across thus far into the planning stage. I haven't educated myself fully about the mechanics portion yet, but I shall soon, and I don't foresee it being a large problem.
Thanks for the help!