Good topic Justin. I think most of our answers will be at least bordering on theory. I suspect that in real long bows or even moderately long bows they will tend to loose efficiency due to vibration in the limbs even though they can still store sufficient energy. A very heavy draw weight elb can remain pretty efficient because the limbs are thick and relatively narrow. Deeper cross sections vibrate less. I think the key to any good design is both high energy storage and low vibration. I have found for instance that a 50# elb or even a flatbow for that matter made from a dense wood like osage can't really be made that efficient if it is too long unless a longer section of the middle is kept stiff. The wood just won't be stiff enough to avoid bulging in the final stages of the power stroke. A very light wood or even medium dense wood like pecan or maple might very well be idealized at a longer length. I feel pretty sure that there is some kind of ideal ratio that incorporates, length, width, density, and draw weight. All these things can be manipulated by using different tillers and profile shapes. I personaly have found with most bows about 72" long I do best wth a straight bow design and a slight amount of reflex or even straight. My r/d bows seem to peek out around 67" long. Steve
