Sharp hooks ( a how to and lots of argument as to their merits )

[bubby]

I could care less if a static is faster or slower,or what the optimum  length and angle is with them,or at what point its best for the string to lift off in the draw......i just like the sweet smooth draw of them and how nasty sweet  ~90° hooks look    and yeah besides good looks on a bow they do spit an arra to my liking 

Btw...i use steam alone,no straps,n bend it all at once with good results that usually makes a nice clean non torn or splintered wood...such as this 






And blackhawk returns with the perfect response👍👍👍👍

[Badger]

There's a reason why the fastest @10gpp wood-only bow built so far is a long straight stave bow without sharp recurves...

I sure would like to know where you got that statistic because it is quite contrary to my observations and to my experiences

Don't take it too literally. Rather, one of the fastest. I'm referring to one of Tim Baker's pecan bows shooting (if y remember right?) 192 fps at 10gpp and 28" draw. There may be or have been bows of similar performance (see your HHB bow on p66 of TBB4), but I'd be surprised if any of they had long 90° hooks.
Don't get me wrong either: I'm not saying (static) recurves are always bad and reduce efficiency. My point is that there is an important trade-off to take into consideration, which I tried to explain above. Just assuming that big hooks will boost performance of any bow is wrong.

Kooi & Bergman 1997 equally conclude that net efficiency of Turkish composites (with rather small static recurves) must be smaller than that of straight-stave bows:
"Notwithstanding this, the efficiency η of the ‘Persian’ bow, and certainly that of the ‘Turkish’ bow, is rather low. This implies that the initial velocity ν is not as large as one would expect on the basis of the static performance.  This is caused by the relatively heavy ears.  These considerations demonstrate why these bows can, inherently, be no better than long straight-end bows; a large part of the available energy remains in the vibrating limbs and string after the arrow
leaves the string"

This is confirmed in practice by tests of Adam Karpowicz (http://www.atarn.org/islamic/Performance/Performance_of_Turkish_bows.htm). None of his bows shoot faster at 10 gpp than 185 fps, which is less than the 190 fps of your own HHB or Tim Baker's pecan board bow. Note that with your HHB recurve there is a nearly immediate lift-off early in the draw, which is required to boost efficiency.

joachim
[/quote]

     I was the one that tested that bow. At 28" and 10 grains per pound it tested at about 170 fps. At 31" it tested at about 58# and was shooting a 500 grain arrow. 170 is still very fast for a straight limbed bow but not the same as 192. The 192 was shot at 31" draw and closer to 8.6 grains per pound. So we have a big difference.

[Eric Krewson]

I have a friend who was at MoJam when Tim shot that 192fps arrow. It seems like he had an unusual release of rearing his body back and jumping forward in conjunction with releasing the arrow.

I could be wrong as this was a long time ago but I remember hearing this from my friend.

It seems like he brought the pecan bow sealed in a container from an arid part of the country as well.

These memories might be the workings of a slightly senile old guy, myself, so don't put too much stock in them.

My friend had just made a tour of a the southwest before stopping at Mojam on his way home to Alabama. He shot in the same speed test with a sinew backed bow with a poundage in the mid 40s, it was as dry as a bone and got he something like 180fps out of it.

[joachimM]

I don't believe anyone said big hooks, they said sharp. Whatever length you need to make them sharp.
  The bottom line is still what cast is achieved with each type and sharp hooks historically have done much better.

Sharp hooks will lift off later in the draw. Same story.
I don't hear anyone arguing against what 's written by Kooi & Bergman: in order of efficiency, working moderate recurve > straight bow > asiatic composite > extreme hickman working recurve

[PatM]

No, I mean what happens if they DON'T lift off?

[Badger]

  Eric, at Mojam everyone shot the same 500 grain arrows regardless of bow weight. They used a different scoring system. Tims bow was 47# and shot at 164 fps. This bow scored higher than any other bow using the scoring system they had. The 192 bow was tested by me as I talked about in my post a few places up. I think the scoring system they used was 100 plus draw weight subtracted from the speed. Tim had a plus 17.

[joachimM]

No, I mean what happens if they DON'T lift off?

Then it's just like having a shorter straight bow with even heavier tips than a regular bow. A textbook example of unwanted dead mass if you ask me.

[PatM]

So that two inches of lift off at the end of the draw is enough to make the bow pay for all that added mass?
   Many others would say it's the increased string tension early on that is the beneficial part.

[Badger]

  The lift off helps in a couple of ways. It adds to the force draw curve by building weight slower as it becomes effectively a longer bow as it lifts off. It also help with the efficiency by giving leverage back to the arrow at the end of the power stroke making the bow more efficient.

[PatM]

I'm not disputing that lift-off is ideal merely the much thrown out  thought that without lift-off the bow is just a short bow with weighted ends.

[Badger]

I am not sure how you could not have lift off? I can see not having optimum lift off but none is hard to visualize.

[dragonman]

you are all missing some important points...imho.   recurves change the string angle whether they lift off or not....this adds leverage to the draw.....less string angle decreases stacking.... string angle determines the amount of leverage...  this affects arrow speed because you are essentialy getting more weight for less effort, this is how levers of all types work....also recurves that dont lift off still add early draw weight making for a smoother draw,,,and makes the working section work harder, getting more work out of the limbs ( provided they can take it) .  Also if the recurve opens up and " works" this makes a bow more effecient...as I see it anyway!!!....open to be proven wrong though, maybe I'm deluded?

[PatM]

No lift off is achieved by increasing the recurve. The bow Bryce posted likely won't  lift off unless really hauled back.

  dragonman, I am aware of those factors, just trying to focus on this one factor and whether it actually is true or not.

[scp]

Without liftoff, it would be like tying the string below the whole recurved tips. In that case, they are just dead weights attached to a "shorter" bow.

[PatM]

There it is again....