I read- and thoroughly enjoyed- the article!
Personally, I have no idea the origin of the bow. But I have seen the effects of this design. One of the first few attempts I made at a D bow wound up with a slow, bending-too-much in the handle bow. It was weak, slow, and a total failure. I can't even remember why, but I tied a little bow to the back and made a Penobscot out of it- whoooooo boy! It jumped to about 60# and shot better than my other 60# bows. How? Why? No idea then.
It seems that the Penobscot is a careful balancing act. If you start with the main bow being only slightly lighter than the final intended draw weight, then the increase in performance would be slight- or, if the small back bow. strings, and bow-to-bow friction (which might also cause as much trouble as limb hystersis). The few keys to a good one (and things I'm trying right now):
1. low stack back bow with high dry fire speed (so it actually pulls the limbs forward instead of just getting in the way).
2. bend near the handle of the main bow so the short bow won't push against it, causing useless stack
3. main bow very light in mass (and bow weight). I think this is the key. If the bow has the mass of, say, a 30# bow, but has the draw weight and stored energy (which is why the back bow needs to be fast and without stack and both need to be tuned well) of, say, a 65#+ bow, then the bow would have more energy for the arrow and less needed to move the limbs. The bigger the difference you can get in bow weight between the main bow before and the main bow after, I think the greater the performance.
Another big downfall is tuning. If the back bow stacks, begins to break down, or doesn't recover in harmony/more quickly than the main bow, then the bow's harmony will be off and it won't recover like a normal bow of the given draw weight (same way a bow with extra hystersis would rob efficiency). So if the bow's tune is off, then the lower limb mass wouldn't mean anything.
All theoretical, of course
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