Cronographed all 3 of my bows lately and came up with some interesting results. Had correctly spined shafts for all of them and had 2 weights of arrows, 410gr and 520 gr which equated to 8 gpi and a little over 10 gpi.
My shorter 58" bows averaged 7 and 10 fps faster than the 62" with the light arrows, but with the heavier ones they all shot statistically the same.
The 62" is a Toelke Whip, one of the 58" bows is a Thunderstick Mag, and the other one is quite similar to the Mag but made for me by a friend and a bit faster.
Maybe it's just cabin fever, but I would be very interested in some insight in this unexpected surprise.
Nothing. The most efficient bow will always be the most efficient. At higher arrows weights they will come much closer together but the one that is slower at 7gpi will be slower at 12 gpi. That is if the bows are identicle weights and drawn exactly same length each time.
I did actually measure all my bows, and they are all within 1 lb of each other on the scale I was using. Can't guarantee that my draw is totally consistent, but the averages I mentioned were over 20 arrows for each weight for each bow.
That's why I thought it so curious, as I shot a lot of arrows. Even had a buddy try my bows. He draws an inch longer than me so his speeds were a little higher, but the differences remained the same. Short bows faster than longer bow with light arrows, same speed with heavy.
I find my recurves usualy do better with light arrows,and my longbows to best with heavier arrows.
That's just a general thing though,and my current 50lb Hoyt riser with Tradtech limbs seems to be able to handle any arrow wheight I put across it very well.
My target arrows are 350g and my hunting arrows 610g,,it smokes the target arrows and still shoots the heavies at mid 180's.
The only difference I know of with this set up over most of my other bows is "carbon" in the limbs.
Just a no-idea stab in the dark: thicker limbs?
with the longer limbs there is more energy stored in the limbs using a heavier arrow uses more of that energy.
with the shorter limbs less energy is stored however they are much lighter so more of the energy is used by the arrow
english longbows were made extremely long so they could shoot heavy arrows that would penetrate armor
Very good explanations.
Thanks
EzArcher, English longbows were made long so they wouldn't break so easily. A short longbow of English Yew, or any other wood, would struggle to stay alive unless built long. The arrows were heavy, and so were the bodkins, wedge type points, which mostly "rained down" on the enemy and penetrated because they had mass and a very narrow point.
The old bodkin point would penetrate mail armor, but not plate armor at those long distances.
Then how can we compare the English longbow to the Turking/Asian Horn bow. Those little shorties could really zip an arrow and do possibly more damage than an English longbow.
I understand the longer limbs being more effecient but why are they less efficient with the lighter arrow?
I'm wondering if the longer limbed bow has a lower brace height than the other bows.That may help some with heavy arrows.
The comparison isn't necessary since the fighting was conducted differently with each bow. The English (Celts) could put thousands of arrows in the air at a time, and that created havoc among the enemy forces....read Agincourt if you get a chance.
The little bows of the mounted archers...Mongols, were deadly at close range from full gallop, and were much more of a precise weapon. I think the biggest difference in the success rate was the horse, as much as the bow 8^).
I wrote one very long, very wordy paper comparing the archery equipment and the techniques of the Persians and the English during the medieval period. Bottom line, the English warbow was a rugged, reasonably accurate and interchangeable field weapon, while the Persian bows were heighly tuned, personally fitted and finicky weapons. You could dunk an English longbow in the Thames, string it up and grab any arrow off of a supply wagon and get fair results. With a Persian bow you had to get up early and warm the limbs over a brazier of coals in order to string it. Having a partner help didn't hurt, either.
It's also intersting to note that most trick shooting in Persia was done with detuned bows that were much longer and much less curved/recurved than those you see in museums.
The English Warbow, don't forget, was an artillery weapon & not a precise 'target' weapon.
It's effectiveness as a military weapon was based solely on the massed volley shots that we (the English, NOT the Celts. Sorry George) perfected during the Hundred Year's War & most famously used at the battles of Crécy & Agincourt. As George correctly states, the lenght of the English longbow & warbow is a byproduct of the inefficiency of the design. A highly crowned belly will chrysal very easily if compressed too far. Adding length decreases the amount of compression on any single point along it's length.
As Sixby correctly posted above, the most efficient bow is the most efficient, regardless of arrow weight. If it's faster at 8gpp it will be faster at 12gpp
very good point that english longbows were also made longer to support the 120#+ draw weight and 32 inch draw. Let me rephrase my statement above to 'One of the reasons English longbows were made longer were to use heavier arrows.'
there is a good bit of info in The Traditional Boyers Bible Volume 1 pgs. 66-71 about mass placement and bow length.
heres a couple paragraphs from page 66
"Much of the energy stored in long and heavy limbs remains in the limbs after release, becoming hand shock, string twang, and limb vibration. This is why slower moving, very heavy arrows leave the bow quietly. Heavy arrows make bows more efficient because more of the bow's energy has time to leave with them.
..."This is why flight bows are golf club-like:short,low mass, fast-reacting limbs. Flight arrows, arrows light enough not to impede these fast limbs, can be shot much faster than normal weight arrows. The same flight arrow shot from an english war bow of equal weight would be considerably slower."
What I am thinking is the energy stored on 3 bows are about the same providing they drew to the same length with the same weight. However those shorter bows have less total mass weight (arrow+limb+string) to move in the light arrow situation. Once shooting the heavier arrows, the effect from the less (limb+string) weight is no longer significant.
Thanks all for the education, good stuff here as always.
If the most efficient bow is faster regardless of weight, then why is there a 7 to 10 fps difference at the lower weight and the same speed at the higher weight. I know it is not a scientific study just a thought.
I know one bowyer I talked with said that if you wanted to shoot heavy arrows then use a heavier limb core like osage. If you plan on shooting light arrows then use a lighter core like bamboo. I don't know if this is accurate but I do know that mass moves mass.
I don't think bad bows pass up good bows just by adding arrow weight. I think bad bows have farther to go, so they seem to improve more as arrow weight goes up.
Matchchaser , great question but already answered in some of the posts. the heavier arrow uses the energy in the heavy limb more efficiently. thus as you go up in arrow weight the two bows get closer and closer to same speed. However the more efficient bow will still be the better performing bow. If only by a half ft per second. The less efficeint bow will never surpass the performance of the more efficient bow of the same poundage. No matter the conformation of the limb.
Then that means there is not much difference between the performance of bows if you use heavy arrows. The speed bows only have a noticeable advantage with lighter arrows. I like heavy arrows so this is good. I do understand that the more efficient bow loses ground as arrow weight goes up but wouldn't this trend continue? If the less efficient bow made up 5 to 7 fps in a couple gpp then would it still be behind in a couple more gpp? Interesting. Please don't take this as an argument just a thought.
QuoteOriginally posted by JimB:
I understand the longer limbs being more effecient but why are they less efficient with the lighter arrow?
I'm wondering if the longer limbed bow has a lower brace height than the other bows.That may help some with heavy arrows.
The brace height on my bows are all 7.25". Limb core on the Whip is bamboo, and on the fastest 58 incher is maple. I don't know enough about woods to tell if this is the difference. The limbs are a different width, the short bow mentioned above is about 3/8 of an inch wider. The Whip has very narrow limbs.
Good discussion folks, thx for the replies.
Lighter arrows will always extract less energy from the bow.
It's difficult to measure exactly what we get. Bows are like people, we might be built exactly alike, but our performance will vary. You'll find different performance in bows of equal weight, even when made by the same bowyer.
The "Design" of the Bow, That's it ...
Matchchaser, I have tested hundreds of bows and never seen a bow that was less efficient outperform a more efficient bow no matter the arrow weight. If you have two bows of equal weight and one is more efficient it will always be more efficient even though the numbers come closer together the heavier the arrow. They might get close to even but the less efficient bow will never shoot the arrow faster except occasionally within the margin of error. You may get a few shots faster within the margin of error of the chrono but if you shot 100 arrows the more efficient bow would outperform the lesser bow.
An interesting thing is that the more efficient bow will also be the best mannered bow when shooting lighter arrows because it is transferring the energy into the arrow instead of losing the energy in the form of shock and vibration.
Its an old trick to hide a poorly designed bow by saying it is designed to shoot heavy arrows. Basically it is a smokescreen for a shocky bow.
Sixby, in all your testing have you ever noticed any statistical difference in efficiency between different lenghts of longbows?
I've only tested my 3 bows so don't have the advantage of the amount of data you must have collected over the course of your testing.
How is efficiency measured? Could one bow be more efficient at 9 gpp and one bow more efficient at 12 gpp? Thanks for the info.
QuoteOriginally posted by HATCHCHASER:
Then that means there is not much difference between the performance of bows if you use heavy arrows. The speed bows only have a noticeable advantage with lighter arrows. I like heavy arrows so this is good. I do understand that the more efficient bow loses ground as arrow weight goes up but wouldn't this trend continue? If the less efficient bow made up 5 to 7 fps in a couple gpp then would it still be behind in a couple more gpp? Interesting. Please don't take this as an argument just a thought.
The less efficient bow will never take over the more efficient bow.
Look at it this way. That heavy bow limb will remain a heavy bow limb and will sponge up just as much energy to get it moving no matter how heavy an arrow you put on it. You can realize some gains by making the arrow stay on the string longer, but the more efficient bow is also gaining.
You can't outstage physics. Rules is rules. :knothead:
Well Said George.
I have not noticed as much difference in efficiency in bow lengths as I have in bow design. Total design including riser ,. Stiffness ect. Some of the most efficient bows I have seen are 64 in D and R longbows.
A couple of bows tested at the WTT last year were in the hi 90s.
There is a lot of hype put out by some builders about this bow or that bow being the new Valhallah of all bows . That is usually until they are tested under controlled conditions and exact measurements . Some bows are the real deal though and I will give credit where credit is due.
Centaur is the real deal. They were tested against some of the other highly touted bows and although the other bows performed well they were smoked by Centaur. Except for Whippinstick and Sasquatch. They were in that same high 190s class at 10 gpi . those bows were all unbelieveably efficient bows.
I'm not shilling for any of them and have no stake in them. Except for Kirk at Sasquatch I have not even met any of them. But they are what they are. Finely made efficient bows by master bowyers that understand bow dynamics and physics.
So if a bow is more efficient at 9 gpp then it will be more efficient at 12 grains per pound. The efficiency changes as gpp goes up. So you can measure efficiency at any gpp? I was reading about dynamic efficiency on the ACS website and the ACS bows DE measures from 80 to 88 percent with arrows from 360 to 700 grains. Is it not possible for a bow to have it's efficiency maximized for a certain gpp. Again I am not trying to argue. Help me understand here.
I don't class 10 gpp as heavy at all. Do the same test again with 14-15 gpp - that's heavy.
The only way that a heavier arrow would make the bow more "efficient" is if the arrows greater mass allowed it to absorb more of the energy being imparted from the bow through the string to the arrow, thus making the arrow faster.
A bow will always produce energy at the same level of efficiency, the difference is how much of it gets into the arrow. What doesn't make it into the arrow turns into vibrations (noise and hand shock).