All bows require certain grains per pound so there is not excessive vibration/efficiency losses etc.

The question is could you get a way with less gr/lb when using a dacron string as opposed to a FF string?  

The FF string is very unstretchy and causes a more abrupt stop so in theory you would need to use heavier arrows to calm the abrupt stop as much as possible and vice versa for the dacron.

I think the hypothetical answer is no.  The limb mass would carry the dacron string forward further and still cause excessive stress on the limbs just as it does when you dry fire a dacron bow or a ff bow. The string will stop, whether abruptly or not, and that extra energy that did not go into the arrow is going into the limbs.

Hypothetically of course...  

Theoretically, if you made the Dacron string with many more strands, you could get away with a lighter arrow. It is likely the total weight of the arrow plus the string that figures into the calculation....   :cool:

FF will give you about 8 fps second more speed than dacron, I would imagine, you could theoretically shoot a lighter arrow.

As I understand it, with a string that stretches more, it will absorb more of the energy stored in the limbs.  That will effectively make less available to be transferred to the arrow, and less available after the arrow is launched.  This should make for both a slower arrow and less vibration in the limbs after the shot.  If you chose to shoot lighter arrows, you might get the same speed as before but you would have less momentum and kinetic energy due to the lower mass weight of the arrow.

Lots of good stuff here.

"All bows require certain grains per pound so there is not excessive vibration/efficiency losses etc."

Sort of I guess, but they are all different. Some will have less shock vibration, and be more eficient at 5gr/lb then others at 10.

"The question is could you get a way with less gr/lb when using a dacron string as opposed to a FF string?"

You bet, by a significant amount. Of the stored energy, it is split between 3 things...Limb mass and distance traveled, string mass and aerodynamic resistance, and the arrow. Increase the mass or resistance to any one of the 3 and the other two gets or wastes less of the stored energy. Limb loss + string loss + arrow energy equals stored energy always.  


"The FF string is very unstretchy and causes a more abrupt stop so in theory you would need to use heavier arrows to calm the abrupt stop as much as possible and vice versa for the dacron."

There are a LOT of misconceptions about strings. Yes, a skinnier/lighter string will increase noise/vibration for the exact same reason a lighter arrow does. The being stretchy effects the "feel" but doesn't effect performance...O.L.

here is the most controversial question then:

do we need FF strings to gain that edge in arrow speed if you can just use lighter arrows with a dacron string and get the same speed?

Note:  I am not a speed nut, take a look at my signature.  Im just making conversation here  

Do you want the energy in the string or the arrow?    Not a speed nut either but I like horsepower!...O.L.

Good point O.L.  I was only thinking in terms of speed (ironically)  I see now you will get more energy if you use the FF.

Now this is becoming an interesting conversation!

So hypothetically, if you increased the weight of your string and its diameter by going to dacron, it would be fair to say you have effectively reduced the performance of your 60# bow to that of, say, a 55# bow.  Since your 60# bow is now basically a 55# bow, you have not actually reduced the gpp all that much, if at all... Right?

O.L.- Are you saying if I could get the mass weight and diameter of a dacron string equal to that of a FF string, the performance would be equal?

I believe that is negative Molston bc the dacron string stretches which is otherwise known as energy not getting to the arrow.  You could however use a lighter arrow than you would need for the FF and by doing this you would get the same speed from your bow as you would with the FF and a heavier arrow but at a loss in Ft/lbs of energy. (lighter arrow travelling the same speed)

I don't see how that is possible Widow.  If you have reduced arrow weight but added weight to the string and increased its diameter, are the limbs not still pushing the total combined weight of the string and arrow with the addition of increased string diameter's surface resistance?

The stretch of dacron could negatively effect the arrow if it stretched at full draw which would have the same effect as short drawing a non stretchy string.  In this scenario, the limbs not bending as far is what would equate to the loss of performance, not the string.

Likewise,a stretchy string would stretch more at release due to the weight of a heavy arrow than it would a light arrow. Since it would take more energy to move the heavy arrow,  would that not create a longer lever to propel the arrow once the string stopped stretching?  Wouldn't a longer lever impart more force with less energy?

I'm not a scientific guy and have never really given this topic much thought.  Always just twisted up a 16 strand dacron string for my non FF bows.  But O.L. has me thinking about this whole string mass/diameter issue which is giving me some ideas.  I'd like to hear more from O.L. on string misconceptions.

We've explored that a lot dealing with the "flight" stuff. It gets complicated cause in testing a person needs to control all variables and change only the 1 being tested. Making a modern string the same diameter as a Dacron, then it doesn't weigh the same, make them the same weight and their diameters are different. Making them the same diameter results in the numbers being very close, within 1-2%. Make the strings logically and fairly and the split is more like 10-12%

Widoweater, Yes sir, that is what a couple of studies have concluded and published, but they didn't control all the variables, plus there was an obvious bias/agenda wanting folks to believe there was little difference between Dacron and modern strings. The energy stroage/transfer theory is totaly untrue and heres why...

Anyone can do these tests themselves and NOT take my word for it.

A string on a bow is at it's maximum tension at brace height. If you put a scale inline with the string, brace the bow, it'll read so many pounds. As you draw the bow the pounds go DOWN..So...If a string is stretchy, it will be stretched to it's max at brace height. If it stretched during the draw as some visualize, the stored energy between a stretchy string and a non-stretchy string would be different, and it's not.

Now the shot....String tension is going to spike when the bow reaches brace height, if the string stretches, it just allows the tips to move a little more away from the centerline is all. A heavier string due to the momentum it has will go past brace height. One would think that would increase power stroke and does. Based on that it  should increase performance but they don't. They don't gain enough in power stroke to make up for the losses increased mass/diameter caused.

How should we pick a string be it cat gut, linen, Dacron, or music wire??  Breaking strength would be a good starting point with some safety cushion. The only rules of thumb I can find writen is like 5X the bow weight...So a 50# bow needs a 500# test string. Dacron has a 35#-50# breaking strength, so 12-14 strands would be more then enough. DF-97 has 150# breaking strength, so 6 strands would be enough. How many of you shoot strings that small? How many have seen/read string tests with similar apples to apples comparision? NONE.....What you do see is 600# Dacron strings being compared to 2000# FF...How can you draw conclusions from that?


Take any material, say poly rope....Take a 1/4" and put 100# on it...How much does it stretch? Take 3/4" poly rope with the same 100#, how much does it stretch?  Same materials but the stretch will be different due to it's total strength. Same goes with bow strings.

The diameter stuff....How much drag would a 5/16" arrow shaft 20" long have flying sideways at 100 mph? A LOT! With a .100" string 60" long that's exactly what you have. You've got 6 sq/in of parchute we call a string. And that's not counting the serving which travels the farthest and fastest! Would cutting that in half be noticeable? You bet! If we could take and break down where bow efficiency losses occure it would be about 40/60 between limb drag/mass and string drag/mass. Of the strings total losses the diameter part would be close to 50% of the total. Those number will vary depending on arrow mass/speed but it's huge and gets bigger by the square of the velocity as arrow weights get lighter. Folks say that heavier arrows absorb more of the bows energy...Wrong, the limbs and string waste less at lower velocities leaving more for the arrow. An arrow doesn't "absorb" anyhing, all it knows is how much force is apply for how long, and how far...

Do we ever really "dry fire" a bow?...No...The string is a load in itself and that "load" increases by the square of it's velocity. Put a heavy fat string on it and it'll use as much energy as the arrow would.

So...Lets see someone do a string test based on string breaking strength. If one is 600 pounds then the other should be also, or close to it. All we've seen to date is one string compared to another of 4 or 5 times greater strength.

The last few months I've been shooting a 55# bow with 4 strands of DF-97 at 2gr/lb with no failures yet. Would I hunt with such a string? No, not at all but with 40ish# bows, 6 strands is over kill, 8 for 50#, 10 for 60#+.. Many have "reasons" for shooting 12-14 strand strings we typically see but none of the "reasons" are good ones.    ....O.L.

Great info O.L.

Looking at it from the opposite angle.  I should be able to increase my arrow weight and maintain the same (or possibly increase) performance if I make some changes to my string.  Lower to 12 strands, cut strand length by 2", twist loops at 7" instead of 8", put on a 4" serving instead of 6 or 8, and cut my wooly whispers down to the smallest acceptable working diameter.

That is great info O.L.

Tim, Many say well this or that isn't much, by itself, most things arn't that big a deal, it's the 200 "little" things added together starts making a difference. And you guys are right, as we go to lighter strings, silencers and stuff, we should go up in arrow weight. Our over all speed isn't changing but where we're using the available energy is changing, and going where it belongs. Those that take their brand new arrow rocket, put on a thicker string cause they like it quiet, more strands in case they cut one, 2 pound beaver balls, double brass nock sets, 12" of double thick serving, leather limb tip protectors, camo tape on the limbs,..ect...They're getting 40# worth of performance out of a 60# bow!

  The serving, yep, that's a biggy, dropping from 14 or 16 to 12, not so much so but doesn't hurt for sure. Going from 16 to 8 however is a big jump. Silencers, don't hurt a lot unless they weigh a lot. String loops, not so much either. Part of where the losses come from is how far they travel. 10 grains in the serving area has as much impact as 40-50 in the loops cause of the "speed". String loops move 5-6" in the same amount of time as the serving moves 20+", roughly a 4/1 ratio.....O.L.

O.L., wht kind of nock and how aer you serving the string you mention in you post of 4 st. of DF97?
Thanks.

Howard, I double serving just in the finger area. Not so much for the nocks as it is getting off the string clean. Under normal conditions I'd use 6 or 8 strands which is still pretty thin, this is one of those useless flight things that makes you pucker every shot!    ....O.L.

Great explanation OL! With 2gns/lb you do wear ear plugs to protect your hearing I guess?   :D

James, "quiet" is relative, actually it's not bad at all, the bow weighs about 5# and the limbs are 7 ounces of that!   ....O.L.