So, I've been asking myself a question and I was wondering what you guys think the answer would be. This is a 2:1 pulley system to be able to shoot projectiles faster than rubber bands would allow under normal conditions: http://thearbalistguild.forumotion.com/t1229-pulley-system-speed-testing And there are "flipper" types crossbows, what use a lever arm to convert a short but strong pull into a weaker, but faster and longer pull. What do you think are the pros and cons of each type of system? 2:1 Pulley: Pro: the pulleys can be made very lightweight so they don't create a lot of losses of energy Pro: the whole system can be kept very compact Con: the ratio has to remain 2:1, there aren't really any benefits in adding more pulleys Lever arm: Pro: can be made to different ratios Pro: possibly less finicky than pulleys Con: higher mass than a pulley, so likely harder to accelerate and loses more energy Con: much less compact, and the length of the power stroke would depend partly on the length of the lever arms, which is a limitation Overall, I think the pulleys are a better system. I'm also wondering if using heavy steel springs could be good enough to use in colder weather, vs rubber. I'm pretty sure rubber is faster than steel springs, and also quieter. But could steel springs generate a good amount of power, or are they too slow to use with a 2:1 ratio and should be used with lever arms only?