RECURVES ARE NOT FAST!

[toomanyknots]

Nope they are not. They are levers. Just had to get this off my chest, heres a reply to a post on paleoplanet:

"Shoot, my main design is a pyramid with molly/holm tips not bending, plus reflexed. See, a pyramid design is great because it bends super evenly with very little chance of a hinge without even tillering most of the time, bending so evenly reduces set also. But it doesn't shoot very fast. A molly shoots very fast, seeing as it is a very small bow. Smaller bows shoot faster. Why is it a small bow? Because the levers on the end, like static recurves/siyahs, ARE NOT NECESSARY PARTS OF THE BOW! THE REAL BOW IS ONLY THE MIDDLE THAT SHOOTS! I think this is the correct way to look at siyahs/levers/whatever you call em. In regards to why recurves are always deemed as so fast. Now I know working recurves should probably be excluded a little bit as the recurves work a bit, but still use the same principle. It's not that a 70" longbow verses a 70" recurves results in the recurve being faster. It's a 70" long verses a 60" bow with 5" recurves results in the smaller bow being faster. The primary function of recurves has absolutely NOTHING to do with increasing the speed of a bow. In fact more mass on a bow could only decrease speed. If you think about it's just funny that we as bowyers who of all people should understand the dynamics of bows all say that "recurves are fast". I must say this again as I cannot stand the dogma that gets thrown around.

THE PRIMARY FUNCTION OF RECURVES HAS NOTHING TO DO WITH SPEED.

It is all leverage, plain and simple. Small bows stack and a 50" 60# at 28" bow , although very fast, with no recurves/siyahs/molly levers is anything but joy to shoot because of stack. Add some light molly levers on there, and there ya go. If ya wanna follow the principle of leverage farther, then you would recurve your levers, at whatever degrees results in a 90 degrees angle with the string and the recurve at full draw, with would be the strongest angle. Anything less than a 90 degrees at full draw and you start to stack. Sooooooo a lazy mans method for a good preforming bow would be...............

- Dependablity, low set, as well as ease of tiller (Or cookie cutter bow method, lazy, ) of the pyramid design.
- Preformance of a smaller a bow, as small as the material will allow to reach drawweight at drawlength.
- Non working recurves/siyahs/levers at such an angle to reach no more than 90 degrees at fulldraw resulting in a smooth drawing bow. Perferably
  as light strong and long as functional. 5" I find usually does a great job of reducing set. 45 degrees to the bow is the only way I have tried yet."

Just saying, small bows are fast. Recurves are levers. Small bows with recurves are fast bows with levers.  

[aero86]

i know that generally, on the horn bows, the siyahs added early draw weight, but other than that, idk!  lol

[toomanyknots]

"i know that generally, on the horn bows, the siyahs added early draw weight"

But they don't, thats what I'm saying. That is a misunderstanding. A small bow with the same brace height as a longer bow is going to have higher early draw weight. The siyahs are there for leverage and nothing more. A static recurve stores no energy and therefor has nothing to do with increased energy as brace.

[NTD]

What!?!?                        Have you read the TBB's?  They do more than just reduce stack on short bows.  And they can be built with minimal weight in the tips.  I doubt there are many straight profile bows that can touch the speed of a Marc St. Louis deflex recurve.

[Kegan]

What!?!?                        Have you read the TBB's?  They do more than just reduce stack on short bows.  And they can be built with minimal weight in the tips.  I doubt there are many straight profile bows that can touch the speed of a Marc St. Louis deflex recurve.

Ditto, but I think he said his reflexed recurves are still faster than the deflexed recurves?

[NTD]

Do you mean recurves with only reflex?  The Deflex recurves I meant are his R/D recurves.

[Badger]

     I think recurves have the potential to be the fastest because they store the most energy. Recurves if not designed properly can also have the most problems. Mark St Louis has made many recurve self bows that exceed the 180 fps mark using the 10 grain per pound 28" draw standard. You will likley never see a straight bow that ever exceeds that number. R/d bows I believe have the potential to be just about as fast and I think in most cases are faster because they will usually have lower mass outer limbs and be more efficient. That being said I still favor the slightly reflexed straight bow designs with light weight outer limbs. They seem to be just a tad slower when optimized but much easier to optimize. Between the Molly and the pyramid the molly will ususally get the nod if properly tillered where the front virew of the bow matches the tiller shape but just slightly modifying the outer limbs on the pyramid into an eifel tower shape will get you right back even with them. Good post here! We used to have some great discussions on these things. Steve

[George Tsoukalas]

I am not a fan of the recurve concept on a selfbow. They are time consuming to build.  Most these days build recurves with static tips which means more weight on the tips which slows the bow down. Jawge

[Justin Snyder]

You are right in that they are leavers. BUT..... leavers are often used to increase speed. Put a ruler on a pencil to make a little teeter totter. First put the pencil in the middle of the ruler. Put something on one end then smack the other end down. The object will fly. Now try it with the pencil 2 inches away from the end you will smack. It will fly a lot farther. WHY?? ?? ?? Because the leaver made it travel faster.

Reflex equates to early draw weight. If the recurve (leaver) makes the tips 4" reflexed how can it not add early weight. Early draw weight equates to higher stored energy which (if the bow is designed efficient) means more energy into the arrow. More energy into the arrow means more speed.

The PRIMARY purpose of recurving is more complicated than just making a bow easier to draw. Pulling 65# requires the same energy whether the bow stacks or not. Yes, the weight builds faster at the end if the bow stacks, but it still requires 65# of pull to get it back. But by reducing stacking you increase energy put back into the arrow and increase speed.

[gmc]

I do like to flip the tips a little (occasionally), but its still at a cost of more stress in other areas of the limb. The simplicity of a flat limb profile has pulled me in lately, and I'm not giving up much by doing it.

[hammertime]

Just throwing out a couple other questions does a set back-in -the handle or reverse riser add anything to speed?In the first tbb1 it is stated the side profile is what gives a bow its speed but according to the tbb 4 re curves can't be as fast because of the extra mass at the tips? I  think that a well tillered straight forward maybe a little flip at the tips ,is a great performer-Hammertime

[NTD]

Steve, Do you have a results list for WTT wood bows with a description of those bows?

[Lombard]

Justin's example of the mechanical advantage of levers couldn't be any easier to understand. The potential energy stored in the re-curved limb is understandable as well, however when I shoot with my friend who uses a re-curve, his  bow is much louder than my plain old straight limbed selfbow that has an inch and a half of set. As far as hunting goes I'll take my quiet old hog of a bow before his noisy speed demon any old hunting day. 

A question for Steve, who has seen the competition at events hosting flight bows, what bows perform the best?

Another question I have been mulling over, is should the levers be equal or unequal in length? What effect one way or the other does this have on the static fulcrum and the position of the dynamic fulcrum on a bow? 

 

[Ranger B]

The static recurve or "flipping the tips" makes the bow shoot a bit smoother.  Big A and Greg put them through the chrono one year I think and found no gained speed but the bow was much more enjoyable to shoot. 

[Aries]

If you think about a coordinate plain, the bottom being draw length and the side being weight. plot out the points of each pound at each cross section.A bow with a higher mid and early draw weight will have more area under the curve, thus more force at each stage of launching the arrow.

There are trade offs to speed though, such as Lombard pointed out.