So this is actually a continuation of the compression woods topic that I felt was more pertinent here. Based off your drawing I plotted your force curve so I could do some calculations off it. But I also wanted to check to see if I got it right. The first number is the draw length, and last number is draw weight. Does that look right? It’s what I was able to make out from your drawing. I changed the starting point though. You had it starting at 0 inches but really it should start at your brace height (6 in.) since the 6 inches before brace can’t perform any of the work. By-the-way by doing this it makes your shows how impressive your force curve really is. From my excel program I calculated your potential energy as 59 ft•lbs (really it’s work in not potential energy, but it's fine for our purposes). The kinetic energy of your arrow (work out) is around 32 ft•lbs. Therefore, your bows efficiency (work-out/work-in) is around 54%. This was surprising to me, but is reasonable. All the bows I've tested have come out around 50% efficient as well, even store bought fiberglass bows. It may seem low, but I just think that's just how bows work. Basically, the reason your bow is so fast is because it has a great force curve, allowing it store more energy. I don't think it was because of super efficiency. My worst bow with more than 3 inches of set, and horrible stack, was about 48% efficient. Yours is clearly much better but even if it was 48% efficient than it would still shoot an arrow 164 fps than the current 170 fps at 54% efficiency. What did you use for string? I wonder how much of a difference a light nonstretching string would make over a heavier stretchier one.
