Forward set/ reflex and performance...

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hunterguy1991
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Forward set/ reflex and performance...

#1 Post by hunterguy1991 » Tue Mar 10, 2015 1:09 pm

Afternoon all,

I have been dabbling with the warbows for about 6 months now and the bug has well and truly bitten to say the least. I am pretty confident in my making of the bows and have got a few pretty decent ones that are capable of 200+ yards with fairly hefty arrows.

However,

It always seems to be that what ever my bows are capable of I find a video online of one at the same weight exceeding my shots by 40+ yards... now I am constantly trying to better my bows when I make them and distance is a great method of testing them but its a little disheartening when you see someone do so much better with the same weight pull and same weight arrow...

For example, I have a 120lb American Ash/hickory that I have shot EWBS standard arrows out to just over 200 yards... yet a friend of mine has a double yew/hickory laminate that is also 120lbs and he has shot the same style of arrow out nearly 240... the only think I can put it down to is that his bow may be forward set/reflexed on glue up and mine not.

So, my question is, how much does forward setting limbs of a bow actually increase its performance?? Has anyone ever pitted 2 bows that are the same weight against each other but one with a forward set/ reflex and the other without??

Colin

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Re: Forward set/ reflex and performance...

#2 Post by greybeard » Tue Mar 10, 2015 3:09 pm

hunterguy1991 wrote:For example, I have a 120lb American Ash/hickory that I have shot EWBS standard arrows out to just over 200 yards... yet a friend of mine has a double yew/hickory laminate that is also 120lbs and he has shot ............out nearly 240... the only think I can put it down to is that his bow may be forward set/reflexed on glue up and mine not.
Have you swapped the bows and arrows to see if there were any performance differences.

A few points to consider;

Form / technique, quality of loose.

Draw length.

Materials used in bow construction.

Difference in string follow / pre load at brace height.

Physicial mass of bow.
hunterguy1991 wrote:......and he has shot the same style of arrow......
Are the arrows the same as yours in all respects excepting colour?

About the only other alternative is to set up the equipment to do f/d curves to obtain stored energy data, and a program to produce predicted arrow velocity at different percentages of bow efficency.

Comparing your actual arrow velocity using a chronograph with the predicted velocity you will know the bows efficency.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

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Re: Forward set/ reflex and performance...

#3 Post by hunterguy1991 » Tue Mar 10, 2015 5:16 pm

Daryl,

I would love to swap bows but as he lives in Canada and myself here that may be an expensive exercise...

The arrows are identical all but timber... same length, weight, fletching size/length and head...

This then makes the draw lengths the same as in warbow shooting you 'use' the whole arrow...

The bow materials I listed... my bow is American ash/ Hickory where as his is double Yew/ Hickory. From memory they are fairly similar in terms of material properties but id have to check to be sure.

To obtain more preload at brace you would need to reflex the stave, which is the very point I am questioning... a reflexed stave would then also negate some of the set the bow may take...

Colin

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Re: Forward set/ reflex and performance...

#4 Post by Dennis La Varenne » Tue Mar 10, 2015 5:21 pm

Colin,

Additional to Daryl's comments above -

ELBs aren't good candidates for reflexing very much simply because of the greater loading on the narrow belly and the resultant string follow which cancels out the original reflex. I have made them by Perry reflexing by 5 inches on a 70 inch bow of 60lbs@28" only to have the bow lose all of it and come to straight. The loss of reflex is disproportionately large compared to a flatbow. Retaining any kind of set is not guaranteed with these bows unfortunately, but I have done it by Perry reflexing.

However, in view of the above, if you can keep the bow at 0 set, it has to have a greater pre-load on the string than one which has any amount of string follow.

The other alternative is to make the mid-1/3 section of the bow a bit wider and put in a much faster taper in the outer one third of the limbs, even to the point of say 3/8" tips and smaller horns so the limb tip mass is much lower and their dry loose speed is greater.

For your next project bow, I would try Perry reflexing first with up to 8 inches in a bow of your usual length. Apply the backing at the stage that you have it to a good tiller at bracing height, not before. If you do it before early tillering, you will lose it all during early tillering.

Applying the backing lam in Perry reflexing when the bow is brace-height tillered keeps the reflex shape evenly distributed along the bow's length because in reflex, it takes the reverse bend it has at low brace height.

You will still lose most / all of it by the time the bow is ready to shoot, but it still beats any bow with string follow.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

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Re: Forward set/ reflex and performance...

#5 Post by greybeard » Tue Mar 10, 2015 6:42 pm

hunterguy1991 wrote:.......To obtain more preload at brace you would need to reflex the stave, which is the very point I am questioning... a reflexed stave would then also negate some of the set the bow may take...
Is your friends bow reflexed or flat laid?

One other option is to build a bow using the same materials and dimensions. Perhaps he built a better bow.

Bows of identical draw weight will yield varying performance values.

Daryl
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Forward set/ reflex and performance...

#6 Post by hunterguy1991 » Tue Mar 10, 2015 6:54 pm

Thanks both for your thoughts.

I think that if I can get a bow to have no set when unbraced it would be beneficial to its cast. My 110lb Red ash warbow had about 3 inches of reflex as a stave and is now straight when unbraced so it will be interesting to see how it performs in relation to the 120lb American ash bow that has set when unbraced.

Dennis, That 175lb warbow I showed you yesterday that broke the EWBS Livery record had 3 inches of natural reflex in the stave and apparently comes to straight after its un braced... granted it is a stave bow not a laminate bow but I still think the same principle could be applied.

Daryl, Im not sure if it was flat laid or reflexed when it was made, but it was made by a master bowyer in England who has made several bows that hold EWBS distance records with various arrow types.

Here is a link to the video of the bow Im talking about. Jake is the friend of mine and it is the first bow hes using in the video, 3rd he shoots... "goose fletched standard" https://www.youtube.com/watch?v=33LNnyqiQcs

Colin.

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Re: Forward set/ reflex and performance...

#7 Post by Dennis La Varenne » Wed Mar 11, 2015 12:12 am

Colin,
Firstly, a few things about the video -
1. Jake has much better control of his bow than many of the shooters of English archers using heavy warbows.
2. That Joe Gibbs double Yew bow seems to be coming in the lower limb about where the whip-ending begins.
3. The width profile looks very much what I have always considered to be a correct profile for this kind of bow.
4. Note that the bearing arrow's cast surpassed that of the livery arrow.

Comparing a naturally reflexed stave against a Perry reflexed stave, there are the following mechanical differences -
Although the naturally reflexed staves can be spectacular shooters (one of my own Osage flatbows comes to mind), as they bend, the belly wood is always under compression load and the more you bend the greater it is of course, but say that the bow has 2 inches of reflex, then you get a compression loading of draw weight PLUS two inches of reflex.

This is is why you need special wood for a naturally reflexed bow usually found on the upper or tension side of a log or limb which is leaning downhill. When it is removed and split, the tension side then pulls the whole thing into reflex as it dries. The opposite tends to happen to the underside or compression wood from the same tree.

With Perry reflexing, you can easily get a superior bow using average wood because the compression part of the stave before backing is actually pulled into tension at the glue up. That means that from the unbraced position to straight (the amount of reflex) there is NO compression loading being applied to the belly for the distance of reflex to 0. However, the string tension is just as high as on a naturally reflexed bow with as much reflex.

That is the advantage of the Perry reflexed bow and why it can be built to as good a performer as a naturally reflexed stave on average.

The other principle applying to all bows is the fact of the barest minimum amount of wood required to sustain a bow of x-length and y-draw-weight. This was a topic covered in Volume 4 of TBB. I believe that there is a set of maths for calculating it by all accounts and the principle is well-understood by the flight shooting community for obvious reasons. A high dry-loose speed is everything.

However, as with all bows, even with minimum stave mass, the distribution of that mass throughout the bow is critical. Most of us tend to build our ELBs greatly overbuilt in terms of stave mass.

The fact of Jake Fenwick's bow shooting livery arrows further than yours could simply be a fact of his Joe Gibbs Yew bow being of lower mass than yours.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Forward set/ reflex and performance...

#8 Post by Hamish » Wed Mar 11, 2015 4:26 pm

Pretty much what the other guys said. For practical purposes a couple of inches of reflex glued up in a board/lam stave will increase the cast, and give you a bow with little or no set( so will a heat induced reflex in a tree stave). You will need good quality materials(no borderline species, or short grain lam's).
Also I imagine it will be a real bitch to floor tiller and sink the limbs, with the heavy draw bows you like(I have only made reflexed bows to about 65lbs). They are harder to tiller than straight staves as if you don't brace the bow high enough it will try to flip back to a reflexed position.
Narrow elbs also have more of a tendency to twist sideways when reflexed, during tillering so keep an eye out for that. I suspect this won't be as bad because warbow limbs tend to be a lot wider than the bows I make. Nevertheless keep an eye out for it whilst getting the bow to full brace height and don't pull the bow until you have corrected it as you can permanently put in a set sideways.
You have been making some cool bows recently Colin. I admire your energy and hard work. I still haven't tillered any this year, just roughed out a few character staves. Keep up the good work.
Hamish.

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Re: Forward set/ reflex and performance...

#9 Post by hunterguy1991 » Wed Mar 11, 2015 4:45 pm

Dennis,

Jake is an exceptional young archer and can pull bows that you'd think impossible for his stature. Im very much looking forward to shooting with him later this year when he is visiting Aus. I will definitely hand him my 120lb ash bow for a few shots to see what he thinks.

As for his bow, its a beautiful piece of craftsmanship made my a master and the tiller reflects that from what I can see.

I would also expect the standard arrow to shoot further than the Livery as you mentioned as its about 9 grams lighter with shorter feathers and a thinner shaft.


You will have to clarify what you meant by "Perry" reflexing as I've not heard the term before.

Thanks for your thoughts Hamish, appreciated them as with Daryl's and Dennis's.

It will be very difficult to have the stave flip when I tiller it, especially on the really big bows I've made recently because the handles just (only about a mm to spare) fit in the top of my tillering jig so there's not enough room for them to flip over.

I have only made one warbow that had any reflex in is which was the Red Ash one I spoke of... when I split that stave it ended up with about 3 inches of reflex at either end... I tillered that bow no different to any other Ive made and it came out pretty spot on. It now remains straight when unbraced so it should have good cast. I'll find out when I eventually get some horns on it.

Colin

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Re: Forward set/ reflex and performance...

#10 Post by greybeard » Wed Mar 11, 2015 4:51 pm

Dennis La Varenne wrote:....With Perry reflexing, you can easily get a superior bow using average wood because the compression part of the stave before backing is actually pulled into tension at the glue up......
Colin,

Scroll down the following link and look for the replies by Dan Perry [Perry Reflexing]. The information may prove useful if you have not read it before.

http://leatherwall.bowsite.com/tf/lw/th ... &category=

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Forward set/ reflex and performance...

#11 Post by Dennis La Varenne » Wed Mar 11, 2015 8:04 pm

Colin,

I am at Jeff Challacombe's for the next few weeks, so I don't have my TBB Vol. 4 to refer to, but as I have always understood his explanation, only two parts are required to do the job - the body of the bow and the backing lamination.

I cannot remember Dan Perry referring to the use of multiple laminations as the first poster on Leatherwall suggests. I also know that Ben Pearson was using that exact technique on his higher grade target bows back in 1941 according to his Catalogue No. 16 pp. 5. His flatbows were reflexed using either Hickory or Lemonwood to produce a bow with 5 inches of reflex (true!!!!) and that they would NEVER follow the string. I do not believe for one minute that these bows retained that amount of reflex, but they do keep some of it and I have one in my collection at home. So the method is long established.

PERRY REFLEXING
The principle is to reduce the compression load on a bow by first shaping and tillering it to brace height, then applying the backing at this stage with the tillered stave reverse bent into a reflexed shape to at least the same degree as at brace height.

The object is to achieve a high dry-loose speed by increasing the preload on the string by reflexing.

Having the stave glued into reflex actually pulls the limbs into tension on the belly side and pushes the backing layer into compression while the stave is at rest.

When the limbs are braced, the limbs move from a state of compression on the back and tension on the belly to the normal situation of a tensioned back and compressed belly, but that does not occur until the limbs are drawn past straight.

However, the fact of their moving from a compression-tension state at rest through neutral to the normal tension-compression state also stores energy in the limbs WITHOUT the addition of any greater compression load on the belly or tension on the back.

So, a conventional bow will store its draw weight amount of energy in its limbs when drawn from the resting unbraced state to full draw of 28". The Perry reflexed bow of the same draw weight on the other hand will store more energy than the conventional bow because it has had to move its limbs from resting unbraced state with say 3 inches of reflex to full draw, a movement equivalent of 31 inches of draw.

Therefore, the Perry reflexed bow will have a much greater limb speed because its additional 3 inches of movement increases the string preload. The string preload of a reflexed bow arises because for a 6 inch brace height, the limbs of our Perry reflexed bow have had to move 9 inches, whereas a conventional non-reflexed straight bow, the limbs have only had to move 6 inches.

However, the difficult part to get your head around is that this increased limb speed is achieved with the secondary benefit of having the compression equivalent at full draw of a draw of 28 inches with the speed equivalent of a 31" draw because the first 3 inches of the limb movement is from a compression-tension state at rest unbraced to the conventional tension-compression state at full draw.

It has a more beneficial effect than simple heat reflexing a stave into a new shape because heating only serves to remodel the stave and re-align the longitudinal wood fibres to a new position. Even in this new reflexed position, the stave is at a neutral tension-compression state. As soon as bending is started, the back comes under tension and the belly under compression. Hence at a full draw of 28 inches, the tension-compression load is equivalent to a draw of 31 inches.

I have made only a few examples of each type, but the heat reflexed bows always lost a bigger proportion of their reflex than those I reflexed by pulling the stave into reflex and using a backing lamination to keep the body of the bow from 'unreflexing' back to its neutral state so to speak.

I am not sure I have explained this very well. I may have to add some diagrams later I think.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Forward set/ reflex and performance...

#12 Post by hunterguy1991 » Wed Mar 11, 2015 8:37 pm

Dennis,

Correct me if I am wrong, but it sounds as though Perry reflexing is simply gluing in the reflex by tillering a stave to brace and then reverse bending it to glue the backing on rather than heating in the reflex before tillering??

Doesn't sound too different to gluing in reflex by propping the tips up on X inch high blocks and tying the handle down, which is how I would have done it and is common practise in the UK in high end longbows... Also something I have done with a Bamboo backed Howard Hill style longbow I made recently...

I have long pondered the effect of reflex to arrow velocity and have come to the conclusion that a for a bow put in reflex compare to one that is not, the bow that's put in reflex will store more energy at brace (as you mentioned) but will not have more energy in the draw weight at length if both bows are the same... for example, 40lbs at 28 inches is 40lbs at 28 inches, reflex does not change that... What I think does change in a reflexed bow is the rate at which the stored energy is transferred to the bow on release, which I believe is due to the higher stored energy at brace...

Some interesting maths and physics at play there... definitely would like to understand it more than I do now so a trip back to uni may be in order.

Would like to get Neil's (Newzin) thoughts on the matter... hopefully he'll read the thread.

Colin

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Re: Forward set/ reflex and performance...

#13 Post by Mattkaye » Wed Mar 11, 2015 9:20 pm

I have not read every post but I thought I might put this here. Even if the bow and arrow was identical. It you move form one place of the globe to another the gravest and air pressure can differ dramatically. There are zones that have a heavier gravity/or air pressure to our own, and that could make a huge difference ( I'm not a scientist, it's just what I have read in new sciantist, aparantly we have Gravity hot spots all over the planet )

So all the stupid sciance stuff aside ( that I anly read and believe to be true with no exact proof, just what iv read in books and mags ) it might be where you are that's making the difference!

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Re: Forward set/ reflex and performance...

#14 Post by hunterguy1991 » Wed Mar 11, 2015 9:32 pm

It is very possible that the shooting conditions ie. air temp, humidity, wind direction, air pressure, altitude etc are having a negative effect on the shots Im taking. I have done extensive research into ballistics of bullets in extreme long range shooting and know what the effects can be for only very slight changes in atmospheric conditions...

However, I think it is more to do with the performance of the bow that is sapping distance from my shooting in this case and reflexing the staves on glue up may be a way to better improve their performance.

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Re: Forward set/ reflex and performance...

#15 Post by Dennis La Varenne » Thu Mar 12, 2015 8:21 pm

hunterguy1991 wrote:Correct me if I am wrong, but it sounds as though Perry reflexing is simply gluing in the reflex by tillering a stave to brace and then reverse bending it to glue the backing on rather than heating in the reflex before tillering??
That is about it, Colin.

I understand what you are saying - 40lbs at 28" is just that, but the flight blokes reckon that the additional amount of reflex gives the limbs a much higher limb tip or dry loose speed for the same draw weight with the added benefit that the amount of compression on the belly is lower for that same degree of limb speed.

And yes, there would be some very interesting maths at play here.

Mattkaye,
The science of external ballistics is not stupid. It is quite factual and provable. However, I understand that how air pressures affect projectiles in flight is more of a concern at higher altitude than that attainable by arrows. I know the artillery blokes have to have a good handle on it because their shells fly at pretty high altitudes on distant targets and so do the sniping blokes, especially when they are working at high altitudes like Afghanistan.

Colin again,
Hamish above pointed out some good points about reflexing ELBs and he is right. I have had the same problems. Cast is one of the reasons I started making my ELBs with a curved width taper rather than a straight taper from handle to horns being much wider at at the 3/4 length mark than a straight taper allows.

The other thing I started doing at the tillering stage was to leave the area of the handle which sits in the tiller cradle still quite square in fairly narrow jaws so the stave can't rotate. As Hamish pointed out, the beggars have a propensity to rotate in the jaws of the tiller and if it isn't kept dead square on the tiller, it is easy to induce a cast in one or both of the limbs.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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