Bow lenght (performance test)

[bow101]

This topic no doubt has come up before a zillion times..!     At any rate if you have 2 identical bows in draw weight say #50, but different lenght, say one is 64" and other is 58".  Which bow would perform better.
And another test two bows equal weight different lenghts, one is a recurve and one is an American flat bow. 
And these bows are built from the same wood.

[Pappy]

Likely the 58 will and the recurve if your talking about speed alone. I find the shorter harder for me to handle so I will take slower and easier to handle every time. Speed don't mean much to me,sweet drawing and easy in the hand to handle does. Yep another can of worms. I am a total instinctive shooter that only shoots b50 out of the king of wood Osage,hunt from a tree and only shoot off my hand,no cut shelf.  Let the fun begain.
   Pappy   

[Hrothgar]

Ditto what Pappy said.

[lostarrow]

From the few bows I've tested with the chrono so far, the length didn't seem to make much difference. The FG recurve I tested 65#@28" 62"long ,shot a 500gr. arrow @ 165-170 fps avg.
                  50#28"72"long Red oak molly type  shot the same arrow at 155fps.  avg.
                  60#@28" ash molly type 68" long shot 160fps avg.   
  Note : the wood bows were not true mollies. They have a stiff tip @6"-8" blended into the working lever . Tips are about 3/8"  .Both wood bows also have about 1 to 1-1/2" set Nothing spectacular about them. They all have near center shelves and shoot the 60-65# arrow well .I also only have a 26" draw ,so you have to take that into account as well.Taking into account the draw weights they all perform similarly to my eyes. The FG is a Damon Howat btw. I have more to test (bows that went out before I got my chrono) when I can get the guys back for some shooting. I'll post if anything remarkable materialises.

[RyanY]

Longer bows store more energy and therefore will have better performance. Recurves store more energy than longbows but often times are too bulky in the outer limbs to take advantage of the increased energy storage. All this being said, any well made bow of any length or design will perform well.

[rossfactor]

None of this is my own. Just things I've learned from other people, and reinforced in my years of bow building.

Longer bows store more energy, however after 68" or 70" they tend to become less efficient at imparting that energy to the arrow.  The fastest straight bows are generally between 66" and 68".

Besides outer limb mass, the most important thing to improve performance is minimizing damage to the bow limb during tillering (e.g. crushing belly cells) which causes set, but also may increase hysteresis.


Gabe

[rossfactor]

Personally I would add to Ryan's statement like this:

Any well made bow of any "reasonable" length or "reasonable" design will perform well.  There are diminishing returns on design, length and even choice of bow wood, but over a wide range of variables, similar performance can be obtained by adjusting design, length and tiller of the bow.

Just to help avoid futile argument. 

Gabe

[RyanY]

ross, From what I've read, I would argue that longer bows can maintain efficiency to a point until stringmass starts to eat up stored energy. Longer bows can maintain low moving limb mass by having longer handle sections with essentially the same limbs we might see on bows of shorter length and still have the ever increasing energy storage of longer bows.

[rossfactor]

Well, I think string weight places a role but there is also a balance between stored energy and the amount of energy it requires to move a limb.

For straight bows: shorter bows store less energy but require less energy to move their limbs,  long bows store more energy, but require more energy to move their limbs.

I believe that at some point, as a bow gets longer, the amount of stored energy proportionally to the bow limb mass will decrease, and therefore reduce its performance.  There is a happy medium between  stored energy and limb mass. For straight bows, considering most woods, most draw lengths, and most limb designs this is between 66 and 68-70 inches.  Obviously (as I said above) limb damage, set and other things also effect performance.

There have been a lot of "same design, different length" tests for straight, self bows over the years and most often the fastest bows tend to be between 66" and 68".

Gabe

[bow101]

There have been a lot of "same design, different length" tests for straight, self bows over the years and most often the fastest bows tend to be between 66" and 68".

Gabe

I think that pretty well satisfys my curiousity about "same design, different length" .

[Del the cat]

Too many variables, including draw length* to give a meaningful answer.
If they are made to maximise the performance of the wood they will perform similarly IMO.
The longer bow will prob be smoother and prob' have a better safety factor.
E.G. Maybe the short one is faster now, but what about a year down the line.
Del
* I don't fancy the short bow at a 30" draw if they are made of anything but the best bow woods.

[lostarrow]

We also have to remember not to confuse performance with arrow velocity.  A light arrow going fast may  not have the force of a heavy arrow going slower. Speed isn't everything. it's just one part of the equation.