I was pretty heavy in double bows about three or four years ago... Experimenting with geometrys, recurving the back bow, main bow etc... Plotting the F/D curve, all that happy stuff. With the right set up, you can get a very flat F/D curve from the initial draw to full draw, and I suspect that it's possible to have a really hefty initial draw with let off like a compound bow. It's pretty intense getting the back bow/Main bow weight differential right along with getting the geometry nailed along with making the sinew cables. It's one thing to make a bow, stick another on the back and call it a double bow, but it's an exercise in physics to actually see benefits beyond having a regular bow with the ability to alter draw weights by tensioning the back bow in different ways. Tom Brown Jr. described a survival bow in one of his books that was made out of green material and had a second bow to give it more oomph till the main bow lost moisture so it makes one wonder if there are actually three purposes or types of "Penobscot" bows or double bows...1) Adding a second bow to give a weak bow more power, 2) To give variable draw weight, and 3) To actually build a compound bow, and technically one could argue that a double bow that has a flat F/D curve or one that drops is a compound bow.
A lot of stuff to think about... Especially if one usually takes game at 15 to 25 yards which is easily done with a simple D bow.
