String angle and energy

[BowEd]

That fact shows where the energy is coming from on the bows' limb.Longer bow versus shorter bow.

[Selfbowman]

Ok Jim Hamm at one point thought that adding weight to the tips would make a bow faster. Then the slowest bow in the world was built to prove a point. But is there truth in what he was thinking if you distribute that mass thru the whole limb. Meaning The longer bow shoots a heavier arrow farther because of the mass going forward. Train vs Volkswagen . The extra mass with a light arrow does not store the energy the same. You have less drag with a lighter arrow but the bow is now not as efficient. So short bow light arrows And  longbow heavier arrows.

[SDBurntStick]

I have a question and assumption to throw out here.  First, take 3 identical length ttt, same mass bows.  One straight, one deflex/reflex, and one reflex/deflex at tips.  All have tips in line with handle like the straight bow.  At brace the string does not touch the limb on the deflex/reflex.  All bows are drawn to equal draw length and angle from string to tip and straight line to fulcrum point at hand never exceeds 90 degrees. Are the F/D curves different and which shoots the arrow faster?  If so, why?

The only thing that I can reasonably think that would cause the deflex handle to reflex limb to excel is because of the lever effect of having a longer arm during most of the draw cycle.  Essentially saying that the bow will start with high draw weight due to the arc of the limb and the unraveling effect (limb becomes more straight as opposed to arc which makes the distance from string tip to fulcrum longer).  Much like pushing a door in the center vs the handle.  The same force may be exerted but the door with move farther with the gain in leverage.  The straight bow will have a gradual increase but no peaks so to say and the deflex tip bow will have a flatter F/D than the other 2 bows because at brace the bow will act as though it were a shorter straight bow because of the arc but it can unravel and lengthen giving more leverage effect.  It will increase in weight but not gain advantage doing so. 

As far as different length bows, I think this also explains it, but different length bows are apples to oranges.  We have additional variables.  Mass being a big one so there's always a sweet spot.

[bradsmith2010]

there is some nice info on string angle in Vol 4 by Dan Perry,, he talks about string angle and mass etc,, energy storage of string angle and also then has some specs on the energy storage is not as important as one would think on how far an arrow will shoot, I found it very informative, he tells how far the different bows are shooting,,which is a great reference,,

[Selfbowman]

there is some nice info on string angle in Vol 4 by Dan Perry,, he talks about string angle and mass etc,, energy storage of string angle and also then has some specs on the energy storage is not as important as one would think on how far an arrow will shoot, I found it very informative, he tells how far the different bows are shooting,,which is a great reference,,

I guess that’s good reason for me to get vol.4

[BowEd]

With respect to draw length I think they move the same distance. With regard to actual tip travel, they may travel further due to bending in a tighter radius curve.

That fact shows where the energy is coming from on the bows' limb.Longer bow versus shorter bow.

More energy is gotten from the inner limbs with lighter tips than the outer limbs of shorter bows.This might not be the total analogy but I feel it has something to do with it.
I'll explain my observations and reasons for stating this.When tillering removal of wood the same amount of thickness from the inner limbs reduces poundage more than removal of material from the outer limbs.So outer limbs carry less poundage when shooting and inner limbs carry more.
Everyone knows a whip tillered bow is not very efficient shooting heavy arrows.
It correlates with the TBB 4 book on page 117 showing stress break down along a limbs length.Although it is for a D bow but see it hold true for stiff handled bows too.
Whether string angle has a say in this is another thing,but obviously a whip tillered bow would have a higher degree of string angle also.
Making a long bow to work mostly on the outer limbs is about like shooting a short bow.
I've tested the two types myself inner versus outer limb working bows[same poundage bows] and can tell you the whip tillered does not shoot the heavier weight arrow as fast as the inner working limbed bow and it takes it's advantage away from it not having more limb working to store more efficient energy.

[bownarra]

That is why those short horn bows worked so well but no wood could handle that level of string tension.

 Not sure what you mean by this.  Wooden bows aren't limited by string tension.

No short hornbows 'work so 'well' because they are physically light, horn/sinew can store a lot more energy than wood alone and they stored the energy because they bend 'close' to the handle and don't stack until the end of the draw. Wood can't handle the bend radius or energy storage.

[RyanY]

You could theoretically make a hornbow profile bow out of wood with the same bend radius  and energy storage. But it would be extremely thin and wide meaning the limbs would be massive, not to mention the issue with air resistance at what would be huge widths.

[Badger]

   Most bow designs are optimized for the materials they are using. Fiberglass, wood and horn bows are not that far apart when it comes to speed using 10 grain per pound arrows. The horn bows really seem to excel with lighter arrows primarily because they can be made shorter and are more efficient. Most of our energy losses are due to vibration. Energy storage is just one factor and when it comes to wood bows hysteresis is a major cause of energy losses because of over stressing the wood. High energy storing designs are more prone to over stressing and that's why you will often see much lower energy storing designs able to beat them out.