Originally Posted by JoergS
On crossbows, I use stretch factor 4 and no tapering. This way the bands will live long and the hysteresis effect (cooling bands) is less problematic.
You will need plenty of rubber for good performance though. I recommend doubling the results of the calculator.
With factor 4 I suppose you mean 400% elongation?
I have made your bullpup slingshot crossbow, and banded it with 6 layers of TBG per side (tapered 3-2cm).
The draw weight is 80 pounds, but when I shoot it it is weaker than my 15 pound child bow. Why is that?