Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on January 28, 2018, 03:52:38 pm
-
Would the string angle be the red one or the blue one?
-
That is really a good question that I have thought about a million times. I am not 100% sure what the answer is. As far as the string coming out of the nock the string angle relates more to the nock area but as far as force draw goes I suspect it is somewhere about 1/2 in between the two depending on the shape of the limb. In this case the bow is not at full draw yet and the recurve is still opening up so I think it would relate more to the contact point.
-
It's the blue one. That's the main point of the recurve.
Your blue line on the limb side is not marked correctly though.
-
I wasn't quite sure where it should go. In this case should it be wider or narrower?
-
It should go to the handle, just like the red one.
-
Like this?
-
Each part of the limb is responding to the string angle relative to that portion of the limbs angle. The curve is at a lower angle than mid limb obviously so what ever portion of the curve that is in play will have a lower string angle for that portion.
-
Somewhere in TBB there is a drawing(much better that this) that says that the red angle is the string angle.
-
I have seen that before, I still believe every inch of that limb is responding according to its own relative string angle. But when you average it out I imagine that red line would be as close as you could get.
-
This is what bothers me about the whole thing. If you have a leaver and fulcrum it doesn't matter what the leaver is shaped like, it behaves as if it was the red line.Assuming that the crooked line is rigid. Bows unfortunately, bend, and i don't know what that does to the whole system.
-
ok how bout this :)
-
This is what bothers me about the whole thing. If you have a leaver and fulcrum it doesn't matter what the leaver is shaped like, it behaves as if it was the red line.Assuming that the crooked line is rigid. Bows unfortunately, bend, and i don't know what that does to the whole system.
Every part of this limb you show here woud be working very differently under a load because it is not rigid. So every inch of that limb would be responding to the string angle according to its own relation ship to it.
-
You need to draw your red line to the string nock. That drops the string angle a few more degrees.
Overlay a straightened out version of the same bow to examine the difference.
-
You need to draw your red line to the string nock. That drops the string angle a few more degrees.
Overlay a straightened out version of the same bow to examine the difference.
Pat you draw the line to the first contact point on the limb.
-
That's way out at the nock at that draw length.
-
I have seen that before, I still believe every inch of that limb is responding according to its own relative string angle. But when you average it out I imagine that red line would be as close as you could get.
I do, too. I believe Baker was right about the "net" string angle being most important, at least basically, but I did a lot of fooling around with basic limb shapes cut from slats early on, esp. the pyramid types (which really helped me visualize what was happening with different bow limb types).
Anyway, it's hard to describe, but if you cut yourself out some little slats of wood you can watch this pretty easily. make "pyramid" type half bow, bend the limb and watch how it acts. Then flip a little recurve in the tip and watch how it changes. The recurve not only changes how and where the the limb bends, but how and where it bends at various increments of draw.
-
You need to draw your red line to the string nock. That drops the string angle a few more degrees.
Overlay a straightened out version of the same bow to examine the difference.
So where the blue line is?
-
ok how bout this :)
That's a string devil :D :D
-
I do think the blue line is more representative. I think of the limb like a slightly flexible pry bar in your diagram. If you force down a flexible pry bar you run out of leverage when the tip hits the ground. If you added a siyah to your pry bar and a slight outer limb recurve you can keep bearing down on it in a more advantageous manner.
-
In the last picture the string has already lifted off the curves so the nock point would be correct. If it hasn't yet lifted off the curves it goes to the first point of string contact with the limb.
-
Recurves give an improved string angle but more importantly they become longer as they lift off the curves keeping the draw weight from building so fast.
-
So what I'm getting from this is that the recurves change the string angle but not by a lot. in the 2-4 degree range maybe. I think my confusion was in expecting a bigger change. I'm noticing that in a few things, a very small change can make a big difference.
-
DC, a lot of thing affect string angle besides the tips, your tiller has a major affect on string angle, the close to the handle the bend better string angles, stiff outer limb better string angles. R/D bows have great string angles but don't have quite the benfits of the lift off which makes the bow effectively longer giving it lower pull weight gains as it lifts off.
-
So what I'm getting from this is that the recurves change the string angle but not by a lot. in the 2-4 degree range maybe. I think my confusion was in expecting a bigger change. I'm noticing that in a few things, a very small change can make a big difference.
That will depend on length and angle/curve of the tip and draw length. Draw some more extensive diagrams.
-
I may be missing something in the discussion....
String angle has to be an angle. In the first photo, I see the red line going to the drawn string. However, it is the angle between the string and that red line. It is darn close to 90 degrees so that bow will begin to stack badly. Not break...stack.
Picture the base of a right triangle and the vertical line. That angle is 90 degrees. That is what the first photo shows.
Jawge
-
The recurve diminishes the stack.
-
http://www.primitivearcher.com/smf/index.php/topic,61791.0.html
This thread which I've been a part of also delves into string angle.
-
(https://lh3.googleusercontent.com/zsOPFgPlp9TrvMXKv8HnRLhln5Kp7Qyju673JRp5XdO8TxDKUnf6nYxV0sjzJ_7jl9rq7MfsCXL6-bwiX1Occ6lvPzxq6UAMuexvuu-JcW8VNIBePbD0Zax-9C7UQjQbvYfDAx12cnrsIjRPyhhBOBVjZtnVzKijU6orB4tprk6sTGi98j1vbL5O-id027YZXDgV_tHUPzw1GfE0UeeiOKlU-TOvTJLtp5Tv5bUvOh-iZqftv2IEDD-FGtQaYYG93x1ndfyjf2_nREChA8bm9gTHI_v2L1MR9XA-mYDVE8siUtN_R0THRWhqDM2NJSCHKyyD3v04X4YVteqtYIJgKMe8L6kTBffCtbSSwFZUILb1rSqXIGyQDyG4n1awpWWLIWP8l8LANcs6i1Jef4I-ca63DKO3I6j37yMTsavD1oURFY7lHfpNPecL1Nirn_DYerQbs4p-eq3QPDtB1riPsB7MK1Mou8VtKEkiu3WfNhmGj-9WJBoNRLFiEl2n8voy3QNfnGqL_NAbOh8wsNbYJ5VIqCOUP6oMUGXjY71CjKWZOrRE8zxWlNSyEIhrOVZndTrJanoV9HNIm0RpPwvkqcrMz87go-_KSlC1_uIX3FUqMN5JLuRY_xk1YoXxb7KOGOrhwfiiUyel5BqjaEr7xfH7UEtObiWjRw=w249-h342-no)
I always thought string angle is the difference between the green angle and the orange angle. You can tell there is a huge difference between the angles when you draw it like this.
-
+1
like Greg's sketch above
-
Then flip a little recurve in the tip and watch how it changes. The recurve not only changes how and where the the limb bends, but how and where it bends at various increments of draw.
would you say that the flipped tip applies a torque to the end of the limb?
-
String angle is the angle between the string and the limb in the drawn bow. That's it.
Measure it close to the tip.
Other than that it doesn't matter.
In that right triangle from my last post, no matter where you measure, it is going to be 90 degrees from base to vertical line.
Where you measure is only limited by the size of your protractor.
Jawge
-
I don't think you're following the effect of the retro tip, Jawge.
-
Pat, I don't know what a retro tip is. Never heard of it. Static recurve?
If there is a point where the string contacts the limb. String angle can be measured from there at full draw...from limb to string.
Jawge
-
If you guys are talking about string angle I would have to agree with George. I measure it from nearest string contact point to the nearest section of limb that if practical to measure (if there isn't string let off it would be the bottom of the recurve where the string touches it). However, I am not as sure whether there is still benefit or not from a recurve if there is not string let off. Part of me says no, it's only where it last touches the limb. But part of me thinks there's more to it than that, so who knows.
-
So going off the original photo I would say the string angle is the blue lined angle and not the red.
-
gfugal, you have it. :)
One of the purposes of a recurve is to decrease the string angle making for a smoother draw.
Other possible decreases in string angle are deeflex out of the handle, designing the bow longer, semi-recurving (reflexing the tips), etc.
Probably more bought I just woke up from a nap. :)
Jawge
-
I tend to agree but my gut says there is more to this than just the angle. I'll just think some more. ;)
-
would you say that the flipped tip applies a torque to the end of the limb?
[/quote]
Not exactly. This is why I said it was hard to describe, but.... in a regular straight limb, obviously the string applies the force at the tip. The most force is "felt" by the limb close to the handle due to higher leverage, right? Halfway out, the limb "feels" less force/leverage, and even less right at the tips. Everybody knows this.
Putting a recurve or reflex at the end of the limb changes the amounts (or probably more correctly, the proportions/percentages) of this "felt" applied leverage. To my eye, it applies MORE during stringing and early draw to the limb close to the handle, then shifts as the draw progresses.
With a contact recurve, the limb effectively lengthens later in the draw, right? But, really that is proportional to the "original" limb length. What I mean is, if I have a 64" straight bow and a 64" recurved bow, the recurve bow doesn't END it's draw longer, it begins the draw as a shorter bow.
So, say the recurve takes effectively 2" out of the braced bow length. As a proportion of the total, slightly shorter limb applies LESS leverage at the limb base than before, but the midlimb feels a LOT less.....at first. Then, when the limb effectively lengthens later in the draw, the BOW is still getting shorter, but less dramatically because of the recurve. The recurved tip thus continues to apply good leverage to the limb base, and BETTER leverage to the midlimb than early in the draw. This is where the F/D benefits and lower "stacking" come in to play. Non-contact recurves and R/D bows share this benefit, just less so and at lower angles.
The trade-off is of course then that the midlimbs need to be able to handle that extra strain, which is why I and most guys leave the limbs wider out past mid-limb. The recurve can have excessive mass, too and vibration needs to be managed. This is why (I believe) that my best recurves are short and stout. I've seen a lot of new guys try to put huge recurves on a long bow and it's a really tough job.
My best shooting bows have always been R/D lam bows with skinny tips, and 64" or so deflex-recurves with pretty big recurves only extending a couple inches ahead of the handle at most, WITH string bridges.
-
I think our confusion Is we don't have a universal reference point. Here are three potential reference points I drew out in a sketch.
(https://lh3.googleusercontent.com/O4aJYlfwubptICZdzWjlPbzXVHJsybtP86rNC7vVYrK5HyjL3y3Z1KmRtBe_PstDdc7WF1AAkphUPtT_K6iEnFje4QNqza77-InLFvysE7Msl9AC98LsTNhmfB6BD6NaOgXcDosncQnwjMlZXM9WQln4cKDgyxKjipinQpoRs9yy8_FE86QBBlP1YEzSizGwGPz8I8gN5L1N4cfah8utdBLLYhAO1WfJHiP5DXPsqPYtTxdq21DrK6VRekxvarX8Ho-0RJHIR4dNLf1Z9a8Ev32K0nlDHzn8ycTjHdTfqGFwVGo78ZwrNm9uHIvgjqRRdz-Xk8I7kfyGx88zSU1AUtQ_HUmBGKf2BTXKbeX5kgtpvKB6BQLe-3frMs5F0qPtabVMc2O25_bNorhBcQKHMR4K3J453DAEStSQXzyEdtzo0vHRUaarq6JAAhSJUaPjq6rhX-JkHzTIWI4wNWDblejXXyHgnyZ4LoBmXc8NHal3XpKNmEH8Dw96QMsTgrzoLM4-JbO0vpRCrKHaR2KLeWrBEu8apsy_u9bAxxMfZTiTiwVqj-ZD0ECk3e5Dim3E1KHGE-BBT516y9NGD7aZowaTPCJ6U7AUztusgyuR9cSu8Xz8ExBsGKIgERHo_tNNTC9f9u-E1i_i2IZlRkDCapgkl9xE1hfpyw=w293-h316-no)
PatM and a picture from one of the TBB say it's reference point #1 the average of the limbs or something. To be honest, this reference point makes the least sense to me, but as Badger was saying it might be the most accurate to what leverage the limb feels or something. Pretty sure I butchered that summary since I don't quite understand that yet. It just seems to me the angle change between a recurve and non-recurved limbs isn't that significant with this reference point. The 2nd reference point I just made up and hasn't been discussed here yet. The third is the reference point me Simon, and Geroge seem to be using. Maybe there's another reference point not illustrated.
-
Pat, I don't know what a retro tip is. Never heard of it. Static recurve?
If there is a point where the string contacts the limb. String angle can be measured from there at full draw...from limb to string.
Jawge
I thought you had the BB series.
-
gfugal, you have it. :)
One of the purposes of a recurve is to decrease the string angle making for a smoother draw.
Jawge
You seem conflicted. How does it change the string angle if you don't measure string angle in that manner?
-
Ah, gfugal, I thought you had it. :)
Like I said. Angles don't change according to where they are measured. Doesn't matter. Those angles are all the same in your last photo.
String angle is the angle between limb tip and string.
There is a huge difference in string angles between a recurve and straight bow of the same length.
It's all about geometry.
Jawge
-
There is a huge difference in string angles between a recurve and straight bow of the same length.
It's all about geometry.
Jawge
Isn't that what people are trying to show in many of these diagrams? You sound like your arguing against it and then agreeing in the next post.
-
PatM, I don't understand what you think I said I am conflicted about.
I measure string angle from limb tip or point of contact to string.
Yes, I have the TBB's..all of them. In fact one of my bows is featured in #4.
Jawge
-
Ah, gfugal, I thought you had it. :)
Like I said. Angles don't change according to where they are measured. Doesn't matter. Those angles are all the same in your last photo.
String angle is the angle between limb tip and string.
There is a huge difference in string angles between a recurve and straight bow of the same length.
It's all about geometry.
Jawge
Huh? true the position doesn't change. That stays the same regardless of the reference point but angle most certainly does. Angles are measurements just like distance. They both measure the difference between point A to point B. If you change point A the measurement changes. The angle measurements of each of those reference points I listed are different. The blue angle is probably around 135°, the orange angle is probably around 90°, and the purple 45°. Those are very different numbers. But yes, regarldess of reference point the position and effect are the same.
-
No, PatM, that is not what I was trying to do. I was trying to help people understand what string angle is. Jawge
-
Gfugal, if I take the measurement of a right triangle at different points will it not still be 90 degrees? I can take that measurement along any point and it will still be 90 degrees. Jawge
-
Gfugal, if I take the measurement of a right triangle at different points will it not still be 90 degrees? I can take that measurement along any point and it will still be 90 degrees. Jawge
If you measure the right triangle from B to A or A to B yes it will be 90°. it doesn't matter where you start per se. But that's not what I mean by changing the reference point. It's a matter of terminology. By moving the reference point you move the corner of the triangle. The right triangle is no longer a right triangle therefor it is a different angle.
-
Pat, I don't know what a retro tip is. Never heard of it. Static recurve?
If there is a point where the string contacts the limb. String angle can be measured from there at full draw...from limb to string.
Jawge
I thought you had the BB series.
Just cause you have it, or have read it, or have even written some of it doesn't mean we will remember every detail. Why not just tell us what a retro tip is instead of holding us to a difficult standard and sending us on a time-wasting goose chase searching through hundreds of pages of text. If you want us to read it, then at least give us a volume and pg number.
-
g, I looked at your measurements too quickly in the last photo. Your first measurement is string angle. Don't know what the others are or don't know why they were brought up. LOL.
Oh and if you move the corner you still have a right angle. If you just move the corner point you don't have an angle.
Of course, if you change the way you measure you introduce another variable when there is no need to do so.
When we change definitions it confuses people. For the past 3 decades string angle has been measured from limb tip to string.
Jawge
-
g, I looked at your measurements too quickly in the last photo. Your first measurement is string angle. Don't know what the others are or don't know why they were brought up. LOL.
By first one you mean the blue angle or the 3rd reference point, correct (the one that's about 135°)? I don't know why I brought up the verticle reference point other than I could potentially see it being used. The 1st reference point is the one that PatM was having DC change too and he referenced that there was a diagram in the TBB that used that reference point. Springbuck and Badger seemed to know what he was referring to and talked about the average leverage it had on the whole limb, and how Tim Baker thought this "net" reference point was probably more important. Personally, I'm with you and think string angle should be in reference to the tip of the limb to string.
-
Oh and if you move the corner you still have a right angle. If you just move the corner point you don't have an angle.
haha good catch. I was actually thinking of moving the bottom right point of a right triangle vertically and not horizontally. If it was any other triangle but a right triangle any movement at all would change it, whereas the right triangle was the exception. But I still think my point is valid. We aren't talking about measuring it from a different side, but changing what we are measuring altogether.
When we change definitions it confuses people. For the past 3 decades string angle has been measured from limb tip to string.
Jawge
see that's the thing. There doesn't seem to be a consensus on this thread what string angle is. Therefore I thought I would illustrate the potential differences in definitions we might have so we can come to an agreement and move on to what really matters: what the effect this string angle has on the bow.
-
torque (-P
-
Pat, I don't know what a retro tip is. Never heard of it. Static recurve?
If there is a point where the string contacts the limb. String angle can be measured from there at full draw...from limb to string.
Jawge
I thought you had the BB series.
Just cause you have it, or have read it, or have even written some of it doesn't mean we will remember every detail. Why not just tell us what a retro tip is instead of holding us to a difficult standard and sending us on a time-wasting goose chase searching through hundreds of pages of text. If you want us to read it, then at least give us a volume and pg number.
You're reading too much into the statement. I thought George had read them.
If you are really interested you'll look for it yourself and not demand being spoon fed.
In any event it's pretty self-explanatory in the context of this discussion. Tips set back in some manner.
Trying to avoid you guys launching into a siyah versus recurve argument and just lumping them all together.
-
g, I looked at your measurements too quickly in the last photo. Your first measurement is string angle. Don't know what the others are or don't know why they were brought up. LOL.
By first one you mean the blue angle or the 3rd reference point, correct (the one that's about 135°)? I don't know why I brought up the verticle reference point other than I could potentially see it being used. The 1st reference point is the one that PatM was having DC change too and he referenced that there was a diagram in the TBB that used that reference point. Springbuck and Badger seemed to know what he was referring to and talked about the average leverage it had on the whole limb, and how Tim Baker thought this "net" reference point was probably more important. Personally, I'm with you and think string angle should be in reference to the tip of the limb to string.
An average represents it better though. If you had a straight limbed bow drawn to the max the string angle would be 80 degrees. A bow with a siyah retroflexed so that the string barely lifts from the angle at full draw shouldn't be said to have a string angle of 2 degrees.
So the leverage lets you bend the limb as if it's at 95 degrees and feel like it's only say an 80 degree string angle.
-
PatM, I don't understand what you think I said I am conflicted about.
I measure string angle from limb tip or point of contact to string.
Yes, I have the TBB's..all of them. In fact one of my bows is featured in #4.
Jawge
Are you following the recurve variation? What would you say the string angle is of the recurve diagram?
-
Pat, I don't know what a retro tip is. Never heard of it. Static recurve?
If there is a point where the string contacts the limb. String angle can be measured from there at full draw...from limb to string.
Jawge
I thought you had the BB series.
Just cause you have it, or have read it, or have even written some of it doesn't mean we will remember every detail. Why not just tell us what a retro tip is instead of holding us to a difficult standard and sending us on a time-wasting goose chase searching through hundreds of pages of text. If you want us to read it, then at least give us a volume and pg number.
You're reading too much into the statement. I thought George had read them.
If you are really interested you'll look for it yourself and not demand being spoon fed.
In any event it's pretty self-explanatory in the context of this discussion. Tips set back in some manner.
Trying to avoid you guys launching into a siyah versus recurve argument and just lumping them all together.
So basically any tip that is behind the limb such as a recurve or siyah is a retro tip? If so that was easy enough to explain without much effort. But I'll keep an eye out for it when I'm reading, but I don't have the time or desire to rummage through pages of text now.
-
Ah, siyahs, PatM. Why didn't you say so in the first place. LOL. Definitions.
Of course, I've read them.
g, I was talking about the measurement closest to the tip.
Sorry. Loosing steam. Maybe check back in the AM.
Jawge
-
I didn't say siyah because a lot of the diagrams are showing tips inclined back and clearly changing string angle.
People still have this weird thought that a siyah is somehow different from a one piece tip. It seems they still do.
Tim Baker introduced the retroflexed tip term I think to create a generic term for all the types.
So despite all of this nobody seems to be willing to actually come up with a string angle for the recurve in the diagram.
-
So despite all of this nobody seems to be willing to actually come up with a string angle for the recurve in the diagram.
(https://lh3.googleusercontent.com/wZfP_QnW2DuNgRYyIG_7rOqVuigHkUSEieN1Eas9R8_F567qTJW6Qk88Zv8HAiX4dIjAQAHBFvWMGKJxSuYewU88nHn6vpAmHEv__-fOCs9Cljtvx1OoEhXf-_S7vTB-dxHz7ssR3U_v-yUAuGxaYzTGwWM6rCoRVnm3jGd6BFi1DnyPN0tP7fcGTjH4_WKcUxn2Hi7Mkuk4dLnoKsSCho9vZer0mbBEQMw0xfj_jHlZARUcDJgEtp7zauyZsHy7ssxWWiq5SBsM_96KLwtvJZupWIopWbzwGrira6OcTnXFKeLw4b1QwXgcmmPmhxRj6q8wDYQH3mbpe4mYC4NvZdwTTzOqsnPJ3PK8C2Z0oF8gB5NCRALilrdYV-CyzzQ42Q5MrPMVUjVTnCDln8yiwQZhhf1D4-aYSPLOvVgxoaG9BJoeAqa9Nl3VmMsOjPkDhjVhXVsXnZKUjKGyRkwgW_YjhENDZHhBIT9uYAHxj7yRq_gBh7KuYllpXE4xT-ne75kDwdqo46PGj-A4ZP5VwDu1LBzfzc2y_zImkH0iQrm9laYoXsRmwA2krII1C1S0bE6KP2IzBTas1F0RIlhG7oxHeFufkzadNecdq4EOCtgCRoQC7EzNdtMW1mLAGlDB6_HZq2x4rxjqNl1NFhFZ7YH_nPsslA6E1Q=w776-h620-no)
Is that the correct diagram you're looking for? I need pull up my image measuring app to get the actual angles but I don't think that's what you're looking for. If that's incorrect you should enlighten us with your own drawing.
-
Yes, that's the problem Pat. As another example in this picture what angle are the boards meeting at. You could measure the angle right where they touch and get about 1 degree. Or you could stand back and squint a bit and get about 15 degrees(I'm guessing). What it boils down to is there is no way of doing it. But there must be an "effective angle" or something.
-
I didn't say siyah because a lot of the diagrams are showing tips inclined back and clearly changing string angle.
People still have this weird thought that a siyah is somehow different from a one piece tip. It seems they still do.
Tim Baker introduced the retroflexed tip term I think to create a generic term for all the types.
I don't consider siyahs inherently different from recurves. They are after all just different approaches to accomplish the same thing. The only difference is one is made from the limb and thus shortens it, while the other is added on usually lengthening it. But if you plan ahead and design accordingly shortening and lengthening shouldn't be an issue as you get what you wanted anyway.
-
So despite all of this nobody seems to be willing to actually come up with a string angle for the recurve in the diagram.
(https://lh3.googleusercontent.com/5Zk5ngtx-3P_ilRyy4a2wKGDkZbKtMvFJ9hfI_GHei-cpzXgTaCgihl71sHZiVuCRHEo5hbFSlSHaaBDMSINAnYKSN7ICEjKLEUR18_B4rb8smFRIyOAIa184PS42cjwQ7qpaNz4LV58XDhdw4bOTPicb8f58VuQLsc_j5LtWp7_OuVeTnNDibiklw8aEG8CShBQg8V-P8Eqi_LtaZQMtYDTzD3_lo2hhQQ0GJmD1R0DDyOIpwn8LdWLF4Hvim_skESCgiY8XC4vSfuYZ8oUGN7gUjaQaK-0qsF_JKwDx-JaZtVn02YcUwF4vUpzb0pVP74OfLzhAYsOsBjYcSiq0pdenKSBTGtJXTmQbYLsNg0vLs61hQxNhV1ys94rEaO7mSoKCqMeHwgLiX5ImeU_tJfghp-XyK5lRLnpO8kVyVUH20DRmXx52zb9smfPbla37BOwPQL6jUEZCpXt3PLqsQ5pi3Zj-i7CypZz9SIqu6UaBUMk_E3jF9lBVyz-b9184p5HF97NLuOQa4YIQnoBKhsr5QDHacVHGuy7ZYE5SZMrq6ATkRXXN0p4mfkVGzzCiIAYAORGFgkp3vAiiLvcbIKrGbDe6z20XFbPjABd=w768-h614-no)
Is that the correct diagram you're looking for? I need pull up my image measuring app to get the actual angles but I don't think that's what you're looking for. If that's incorrect you should enlighten us with your own drawing.
That's exactly what I mean and I tried to say that when the first diagram was shown. That I think represents the "functional"l string angle.
I think you still need to draw them differently come to think of it more but the basic idea won't be different. You'll still get those two different angles.
-
That's close to 90 degrees.. from the drawn string to the limb provided you measure the way string angle has been measured for decades. It is the right triangle I have been mentioning since yesterday afternoon.
BTW I have yet to see a recurve with that large a string angle. I understand the photo is for illustrative purposes though.
Jawge
-
Can you just ease away from repeating the straight bow limb angle which nobody has argued and venture an opinion on how you establish recurve angle?
-
Pat, you never do establish a firm string angle because it varies over the entire limb, the longer the recurve or straight area at full draw the lower the string angle obviously but there is no set string angle unless you are talking only about a specific portion of limb which we usually talk about toward the tips. When we have a slow build in final inches we simply attribute it to low string angles but no one I have ever known has tried to pin it down to something exact.
-
Yes, it is represented by the first red line on the top extending to the string. It is the angle between string and red line.
-
With a bit of study I would think establishing an effective string angle would be feasible. If you scribe an arc from the recurve tip so that it merges with around mid-limb, it's probably pretty close to what your perception of the string angle is.
-
Yes, it is represented by the first red line on the top extending to the string. It is the angle between string and red line.
Which diagram? I can't see the one on Greg's post anymore.
-
PatM, you could but that would mean leaving the bow full draw for quite a long while. Not something I would do.
Taking an eyeball estimate is sufficient for me.
Jawge
-
I meant on a diagram or picture of course.
-
"Which diagram? I can't see the one on Greg's post anymore."
When I defined it I looked at the first diagram in this thread, PatM.
Way back on Pg 1.
Jawge
-
if I have a 64" straight bow and a 64" recurved bow, the recurve bow doesn't END it's draw longer, it begins the draw as a shorter bow.
So, say the recurve takes effectively 2" out of the braced bow length. As a proportion of the total, slightly shorter limb applies LESS leverage at the limb base than before, but the midlimb feels a LOT less.....at first. Then, when the limb effectively lengthens later in the draw, the BOW is still getting shorter, but less dramatically because of the recurve. The recurved tip thus continues to apply good leverage to the limb base, and BETTER leverage to the midlimb than early in the draw. This is where the F/D benefits and lower "stacking" come in to play. Non-contact recurves and R/D bows share this benefit, just less so and at lower angles.
+1
It's the net length of the lever from the string contact point that counts. Basically, a recurve "stacks" early in the draw: it has a higher draw weight than its length suggests, because early in the draw the recurve doesn't contribute to the effective lever length. (hence the high early draw weight: you're drawing a shorter bow, but it lengthens during the draw).
Basically, you can view the realized lever length (if you keep the bow vertically) as the net vertical projection of the bow arms (including recurves if any). Moment = force times lever length. The shape of the lever (recurved or not) doesn't matter for a particular draw length. Since a recurve opens up during the lever length changes in a different manner than with a straight bow, as explained by Springbuck.
-
"Which diagram? I can't see the one on Greg's post anymore."
When I defined it I looked at the first diagram in this thread, PatM.
Way back on Pg 1.
Jawge
For the recurve....
-
Yes, it is represented by the first red line on the top extending to the string. It is the angle between string and red line.
Which diagram? I can't see the one on Greg's post anymore.
Sorry I edited it so I could put the actual angles in. The image address changed thus breaking the link. I modified the original message so you can see it on my post, but your quote still won't show it. Here it is again
(https://lh3.googleusercontent.com/wZfP_QnW2DuNgRYyIG_7rOqVuigHkUSEieN1Eas9R8_F567qTJW6Qk88Zv8HAiX4dIjAQAHBFvWMGKJxSuYewU88nHn6vpAmHEv__-fOCs9Cljtvx1OoEhXf-_S7vTB-dxHz7ssR3U_v-yUAuGxaYzTGwWM6rCoRVnm3jGd6BFi1DnyPN0tP7fcGTjH4_WKcUxn2Hi7Mkuk4dLnoKsSCho9vZer0mbBEQMw0xfj_jHlZARUcDJgEtp7zauyZsHy7ssxWWiq5SBsM_96KLwtvJZupWIopWbzwGrira6OcTnXFKeLw4b1QwXgcmmPmhxRj6q8wDYQH3mbpe4mYC4NvZdwTTzOqsnPJ3PK8C2Z0oF8gB5NCRALilrdYV-CyzzQ42Q5MrPMVUjVTnCDln8yiwQZhhf1D4-aYSPLOvVgxoaG9BJoeAqa9Nl3VmMsOjPkDhjVhXVsXnZKUjKGyRkwgW_YjhENDZHhBIT9uYAHxj7yRq_gBh7KuYllpXE4xT-ne75kDwdqo46PGj-A4ZP5VwDu1LBzfzc2y_zImkH0iQrm9laYoXsRmwA2krII1C1S0bE6KP2IzBTas1F0RIlhG7oxHeFufkzadNecdq4EOCtgCRoQC7EzNdtMW1mLAGlDB6_HZq2x4rxjqNl1NFhFZ7YH_nPsslA6E1Q=w776-h620-no)
So the Recurve string angle in the above photo is less than the straight limb, at around 72° compared to 79°. That is a difference of around 7°, which is more than what DC was estimating, but still not a lot. However, I noticed that this depiction is far from accurate since the string lengths between the non-recurved bow and recurved bow are not the same. The recurve has a longer string as depicted. Therefore that is not the correct position it would be in for that draw length since would most likely have a string length similar to the non-recurve bow, thus the string angle would be different. If we use my first sketch I think it is a little more accurate. here it is.
(https://lh3.googleusercontent.com/6z64VUGfYNQ-aU0cRmTgRtDiPucVgYIjG4ebZjXPzuWy7Rqg3IoV_pzCosmVqml_lhrY8mHUIJXqUZEkp_ZjXHodFW6UBCVgLNuzlzViFqd8BwgNT9B533hqiht13rAp0YBEje-UUw7wp9J3kIsHeODFEwisMB6PAecdr5vbCTCrdIEj1A-7NGSyoY8my2snBPtQcGtWpi9dZuGq91kTjsOtvMzH2LJPEg0aMFYm5ByJmcx9Fiz3kTjHkLM_QyHhby4bGUeCZwpQvPikC4BKG9KZrc1eiAkc7gyklaOxWTuIzlwssJ73gLGq2dTjvHJHRe0eIjI1-2r5JuwYAtSXoF9_3IQGU3hoYG9Dv1c-BUufkSHTSdFQo7GQWUVxvZ40iUQ4-7-9R4KdtSYwvTRo8PnNz6iYLthUj0gpcAuqqBMWz3szPscBaQb7ulF4XO7z6e4A0t-CBCFRctmdwlUcYuUnuyYSX_NS4LY3lk8BiHYAzs4ENmGXewN-0sI42_n5X03NtGjSG0MIzxLDhKvMubJc5HC1sc-ebY5i9Hff77fjGABZwLWCSdQM4QW_6p-Y1YxtCwOsx4DRkKaVolniV3QD-zOwK2FcW7wrIFNKA_GB5uIKEtXo53bydQH_zv8TOtUtkQAzswO8FLQ3BJPe4y6oicxgcACtQA=w455-h625-no)
Look at the bottom limbs. Notice that it is drawn so both have the same string length, and draw length. This causes the tip position to be in the same spot. I can't say this would be the case in every instance but they would be much closer in practice than what was depicted in the image above. Assuming the tips are in the same position as I drew them here, what does that do to the string angle if the reference point is the average or "net reference point PatM, and Tim Baker use? It's the same sting angle for both the recurve and the straight limb! (see the black angle at the bottom which is 64°) This is because both tips are at the same spot. However, if you measured the recurve string angle from the limb before the recurve, it gives a much higher string angle (76°). Therefore the recurve is bending the limb to a (potentially higher string angle of 76°, but it does so in actuality with a lower string angle of 64°). Hence you can get better bend out of a limb but with better string angle too. If you tried to get that same bend in the straight limb the string angle would increase much higher than the 64° it is at now. So to summarize: recurves bend the working limbs farther at similar draw lengths while still maintaining good string angle, thus creating more stored energy. I don't know if that made sense to anyone else but it does to me.
-
if I have a 64" straight bow and a 64" recurved bow, the recurve bow doesn't END it's draw longer, it begins the draw as a shorter bow.
So, say the recurve takes effectively 2" out of the braced bow length. As a proportion of the total, slightly shorter limb applies LESS leverage at the limb base than before, but the midlimb feels a LOT less.....at first. Then, when the limb effectively lengthens later in the draw, the BOW is still getting shorter, but less dramatically because of the recurve. The recurved tip thus continues to apply good leverage to the limb base, and BETTER leverage to the midlimb than early in the draw. This is where the F/D benefits and lower "stacking" come in to play. Non-contact recurves and R/D bows share this benefit, just less so and at lower angles.
+1
It's the net length of the lever from the string contact point that counts. Basically, a recurve "stacks" early in the draw: it has a higher draw weight than its length suggests, because early in the draw the recurve doesn't contribute to the effective lever length. (hence the high early draw weight: you're drawing a shorter bow, but it lengthens during the draw).
Basically, you can view the realized lever length (if you keep the bow vertically) as the net vertical projection of the bow arms (including recurves if any). Moment = force times lever length. The shape of the lever (recurved or not) doesn't matter for a particular draw length. Since a recurve opens up during the lever length changes in a different manner than with a straight bow, as explained by Springbuck.
+1 as well,
Would you say that my summary "recurves bend the working limbs farther at similar draw lengths while still maintaining good string angle, thus creating more stored energy." agrees with what you guys are saying?
-
I think our confusion Is we don't have a universal reference point. Here are three potential reference points I drew out in a sketch.
(https://lh3.googleusercontent.com/O4aJYlfwubptICZdzWjlPbzXVHJsybtP86rNC7vVYrK5HyjL3y3Z1KmRtBe_PstDdc7WF1AAkphUPtT_K6iEnFje4QNqza77-InLFvysE7Msl9AC98LsTNhmfB6BD6NaOgXcDosncQnwjMlZXM9WQln4cKDgyxKjipinQpoRs9yy8_FE86QBBlP1YEzSizGwGPz8I8gN5L1N4cfah8utdBLLYhAO1WfJHiP5DXPsqPYtTxdq21DrK6VRekxvarX8Ho-0RJHIR4dNLf1Z9a8Ev32K0nlDHzn8ycTjHdTfqGFwVGo78ZwrNm9uHIvgjqRRdz-Xk8I7kfyGx88zSU1AUtQ_HUmBGKf2BTXKbeX5kgtpvKB6BQLe-3frMs5F0qPtabVMc2O25_bNorhBcQKHMR4K3J453DAEStSQXzyEdtzo0vHRUaarq6JAAhSJUaPjq6rhX-JkHzTIWI4wNWDblejXXyHgnyZ4LoBmXc8NHal3XpKNmEH8Dw96QMsTgrzoLM4-JbO0vpRCrKHaR2KLeWrBEu8apsy_u9bAxxMfZTiTiwVqj-ZD0ECk3e5Dim3E1KHGE-BBT516y9NGD7aZowaTPCJ6U7AUztusgyuR9cSu8Xz8ExBsGKIgERHo_tNNTC9f9u-E1i_i2IZlRkDCapgkl9xE1hfpyw=w293-h316-no)
PatM and a picture from one of the TBB say it's reference point #1 the average of the limbs or something. To be honest, this reference point makes the least sense to me, but as Badger was saying it might be the most accurate to what leverage the limb feels or something. Pretty sure I butchered that summary since I don't quite understand that yet. It just seems to me the angle change between a recurve and non-recurved limbs isn't that significant with this reference point. The 2nd reference point I just made up and hasn't been discussed here yet. The third is the reference point me Simon, and Geroge seem to be using. Maybe there's another reference point not illustrated.
So I just realized this photo wasn't showing before (dang google photo and it's privacy settings). IT should be visible now. That might explain George's confusion when I was talking about reference points. Sorry about that.
-
Green curved line. Top limb. Last photo.
-
Not shown ...second to last photo.
-
I don't think Don is going to get his recurve string angle question answered on this thread at this point.
-
I am realising that everyone(except maybe Jawge :D :D) is just as unsure as I am. I'm not even sure how important it is. Sometimes though, an insignificant piece of knowledge can lead to huge gains. I sometimes wish that I could sit down with my old physics teachers and discuss this kind of thing but they're all dead now. They had the ability to put stuff into plain English. I think the difficulty comes with the fact that because the limb is bending things are changing constantly and out drawings are only freezing one moment in time. Maybe if we took a video of a recurve being drawn and then measured these angles in each frame some kind of order might come out of it.
-
LOL. This will be the third time I've defined how I view string angle, PATM.
Pg 1 Photo 1...
It is the angle represented by the string and the red line which does not quite intersect the string but would if continued. The angle appears to be 90 degrees.
Jawge
-
Do you mean this angle George?
-
That would mean recurving increases string angle. You can determine that from the other diagram.
-
Wow
-
Yes, DC. Jawge
-
If I erase the first post will this whole thread go away? ::) :-[ :-\
-
Try comparing the angles of the straight limbed bow and the recurve the way George thinks it should be measured. Let me know the numbers.
-
If I erase the first post will this whole thread go away? ::) :-[ :-\
Hey now I've put a lot of effort and time into this post with all my diagrams. I don't know if anyone understood them haha, but at least they're out there for now for others nonetheless.
-
I think DC has an answer but doesn't want to accept it. There is no single string angel. Any point you measure it at will be different. The lower it is overall the better your fdc will be. Recurves do improve string angle greatly at the nock and curve area. Other types of bows like DR for instance may have a lower overall average string angle. The recurve still has a significant advantage because it is effectively shorter early in the draw and gets longer as you draw it further reducing the rate of weight gain. But the string angle is what it is wherever you decide to measure it at and you have to decide where it is most important on the particular design you are working on. If you only had a 2" radius curve right at the tip of your bow the string angle would be very low at that one point but overall not much.
-
The recurve still has a significant advantage because it is effectively shorter early in the draw and gets longer as you draw it further .
DC, is this what you hoped to discuss?
-
I just want to hear George's explanation of how recurving lowers string angles while simultaneously increasing them and then I'll move on.
-
DC, I looked at it fast I would go right to the limb.
PatM, recurving lowers string angles.
When did I say it increases them?
Jawge
-
When you showed where you could measure the string angle for a recurve. That angle is larger for a recurve. Actually measure it.
If it decreasesstring angles then it seems reasonable to show HOW, no? To do that you need to let go the line bridging the limb and the recurve as a reference point because it lies to you.
-
Pat, those diagrams were for illustrative purposes.
They are very similar to what the string angle would be at brace...not full draw.
At full draw, string angle is small in a recurve.
I don't have to measure it. I can see it with my eyes. Jawge
-
Pat, those diagrams were for illustrative purposes.
They are very similar to what the string angle would be at brace...not full draw.
At full draw, string angle is small in a recurve.
I don't have to measure it. I can see it with my eyes. Jawge
Aaaargh! There's a whole bunch of pictures showing full draw on here. Draw your connecting line like the first pic (where you insist it is measured only) and measure the angle. It's over 90 degrees.
-
I think DC has an answer but doesn't want to accept it.
All I wanted to know was if it was the red one or the blue one. It was knowledge I thought I might need for thinking more about the whole recurve thing.
-
You tried but these threads always get mired by people more into definitions and nomenclature than the actual mechanics of what others are trying to understand.
It's like when someone asks how much one inch of set is slowing his bow and he gets six pages of the difference between set and string follow and not a single response of "about 2 fps".
-
it's all good though. Things like this make people think, that can't ever be bad.
-
Exactly! The drawings are not accurate! Recurving decreases string angle at full draw. I've said that several times. Jawge
-
I can't believe this.... Pick the most accurate drawing or do one yourself and measure along the line you insist is the only one.
Just show us how you are getting a lower angle measuring that way.
-
I would measure the angle from string to recurve. How would you measure it?
Look at some real bows, Pat. Not the drawings.
Jawge
-
Most of the diagrams quite adequately illustrate the angles. A real bow will still show the same mechanics and angles even if to a more or less degree. The relation between the two will not change.
Just show where you are measuring to on the recurve. Go with one with a sharp angle at the "elbow" to make things more definite.
-
Pat, I've described and shown how I measure by referencing the drawings several times in previous posts. Please go back and reread them.
I don't know what else to say that I haven't said.
Please measure the string angle the way you would like too.
It really does not matter as long as you are consistent between different types of bows.
Jawge
-
Unreal.
-
Once more, I measure string angle at the tips just below the nocks from limb to string.
Pat, if you do not agree. That's ok.
You possibly have a better way of doing it. That is fine too.
Jawge
-
Would the string angle be the red one or the blue one?
DC, it is the blue one. That is the only one that makes sense for comparison, as it fit's with experience. We know the recurve makes a difference, that string angle makes a difference.
1. You will only find ONE angle to measure similarly on a straight limbed bow, the two angles are one in the same on a straight limbed bow.
2. The red angle is effectively the same as if the recurve was not there, so similar angle would not explain the difference in how it feels when pulling (the difference in stack).
So there it is, the blue (ie: as close to the point of contact as you can measure, almost infinitely so).
This is for common statics, i suspect you'd have to treat working recurves and very drastic recurves a little differently, but similar principles apply.
Now, if we'd like to get into a discussion of the physics of why there is a difference, I'd be glad to put my physics teacher hat back on and present that in another thread. Some have skirted it here, but not nailed it down.
-
Finally.
-
Now, if we'd like to get into a discussion of the physics of why there is a difference, I'd be glad to put my physics teacher hat back on and present that in another thread. Some have skirted it here, but not nailed it down.
Please do ;D ;D ;D