Recurve shooting machine

Big.Dave

New member
I was just looking round Utube when I found this vid of a Win&Win bow being shot nothing new there but then I noticed that the machine that was releasing the string mimicked the release from the fingers.

Have a look
[video]http://youtu.be/xTbF2TtiWhg[/video]
 
D

Deleted member 7654

Guest
Hey, nice video. It shows nicely that the spine selection on a modern bow is about tuning the oscillations of the system not about the paradox of bending the arrow around a bow. (I expect that will fall on deaf/uncomprehending ears still :bang:)
Talking of machines, I was looking at a book about Hickman (the father of scientific archery) There was a pic of him with this machine for plotting the force draw curve of a bow automatically.
You stood on the base plate of the machine, hooked on the string and then pulled up on the grip of the bow (a bit like using a stringer) and it plotted the graph as you pulled the bow up!
I might try and re-create it, there were some good pics and diagrams but not enough detail. I couldn't find any further info on t'web.
Del
 

EvadingGrid

New member
Hey, nice video. It shows nicely that the spine selection on a modern bow is about tuning the oscillations of the system not about the paradox of bending the arrow around a bow. (I expect that will fall on deaf/uncomprehending ears still :bang:)
Talking of machines, I was looking at a book about Hickman (the father of scientific archery) There was a pic of him with this machine for plotting the force draw curve of a bow automatically.
You stood on the base plate of the machine, hooked on the string and then pulled up on the grip of the bow (a bit like using a stringer) and it plotted the graph as you pulled the bow up!
I might try and re-create it, there were some good pics and diagrams but not enough detail. I couldn't find any further info on t'web.
Del
I don't understand, this is new to me, can you possibly explain or point me in the right direction please ?
 

BigShot

New member
Watching video number 2 in that series YouTube - Archery Slow Motion W&W TF Apecs 2 ...
...it looks to me like the damper/weight on the end of the long rod doesn't move until the arrow has left the bow and the bow has left the hand. (Thus the shot is complete and it wouldn't affect the shot if you danced a jig, dropped your arm or made a flamboyant hip-movement because you thought it looked good.)

That being the case (and me being a beginner and thus prone to questions about potentially 'obvious' things) what is the damper actually for?
 
D

Deleted member 7654

Guest
Which bit do you want explaining? Paradox? (The following all assumes a right handed archer)
If you take a longbow with a nice fat grip and clamp it rigidly and put an arrow on the string at brace height the arrow will be pointing a long way to the left*.
Whereas at full draw it will be pointing only a little to the left.
The 'paradox' is therefore why doesn't the arrow fly off to the left when it is loosed as the string returns to brace height?
The answer being that it flexes around the big fat grip.

*As a deliberately exagerated example.
If the grip of the bow was 6" wide, (that's 3" either side of the centreline) and the bracing height was just 3" then the arrow would be pointing left at 45 degrees when placed on the string at brace height!
But at a full draw of 28" it would only be pointing left by the angle whose tangent is 3/28 which happens to be 6.1 degrees.
I hope that clarifies it. If you still don't get it then I'd suggest drawing out the above example.

The 'tuning' issue is about the deflection of the string as it is released coupled to the flexing of the limbs and arrow oscillating as a system. This needs to be tuned so that the arrow flexes in a way that allows a clean consistent release. e.g you don't want it's tail end clattering into the riser.

Plenty of people insist that both these phenomena are the same and are both somehow paradoxical.
I see no paradox in the fact that a centre shot bow throws the arrows out straight. I do see a paradox in the way a longbow will thow an arrow out straight when if let down slowly you can see the arrow 'should' go hard to the left.
Del
 

joetapley

New member
To clarify:

If you launched an arrow (with some sort of machine) travelling in some direction and the arrow being launched at say a 45 degree angle to the arrow launch direction then the arrow would continue to travel (with a bit of a wobble) in the direction it was launched. i.e. arrows don't travel in the direction they are pointing (same can apply to a car skidding on an icy road).

Archers paradox originally related to why doesn't the back of the arrow hit the (longbow) riser as the nock was assumed to travel towards it and hence the arrow was launched at an angle to its travel direction with the back of the arrow heading straight into the riser. These days "paradox" seems to be used to mean the flexing of the arrow during the power stroke and sometimes the vibration of the arrow in flight.
 

reiver

New member
Interesting video to see how the string moves from side to side before the arrow is released from it. But it will need greater minds than mine to know how that information can be used to help me tune my setup!
 

joetapley

New member
Interesting video to see how the string moves from side to side before the arrow is released from it. But it will need greater minds than mine to know how that information can be used to help me tune my setup!
Simple answer is that it doesn't. The various bow set-up and tuning methods are purely pragmatic and based on tens of thousands of hours of testing. Having said that understanding how the bow/arrow/archer system works can give some understanding of how the existing methods basically work. To date no set-up/tuning method (that actually works) has originated from some theoretical basis.
 

Suppards

New member
I'm sooo disappointed. :cryingeye

From the thread title I thought this would be all about the recurve shooting machine that is Brady Ellison! :duh:
 

moo-mop

New member
Nothing new about such a machine. Such a set-up was used to try and experimentally understand the physics behind bracing height effects back in 1990 (I have a hard copy of the paper somewhere). See the more recent paper discussing this paper if you like: http://www.archery.metu.edu.tr/docs/bowarrowinteraction.pdf. From a sports science/physics point of view on understanding the bow-arrow system when shot by an archer it can useful experimentally to take the archer out of the question, but from a particular archer's point of view this is not so useful, as there's no published data on permissible extrapolations of what has been found out, as far as I've seen.

Aside: Joe tuning systems (bareshaft etc) to me seem to have come about when that they seem sensible theoretically and when they are certainly are used by better archers than most, rather than direct and independent testing of how much effects the changes recommended in such systems actually have in many particular cases over thousands of arrows.
 

joetapley

New member
Aside: Joe tuning systems (bareshaft etc) to me seem to have come about when that they seem sensible theoretically and when they are certainly are used by better archers than most, rather than direct and independent testing of how much effects the changes recommended in such systems actually have in many particular cases over thousands of arrows.
I think that's true for recent history. Any suggested tuning system to be taken seriously needs a) An endorsement by top level coaches & archers (practical testing) and b) A sensible theoretical underpinning if only at an elementary level.

So bare shaft tuning meets both criteria. The 1980's walk back - look at arrow pattern suggestion has neither (the only comment from the "elites" being it doesn't work).

However the bare shaft method was originally suggested 1n 1963. At that time I doubt if there was much of any suggested theoretical basis and guess it was principally based on practical testing (a spin off from group tuning?)

On a practical level club archers seem pretty open to any tuning suggestion whatever its merits or lack of. The arrow pattern method has been fairly widely used for 30 years or so despite having zero credibility.

There was one quite illuminating exchange in an early Archery UK where one coach queried why the arrow pattern method in the GNAS coaching manual was the complete opposite of the generally published one. The coaching manual author's response was "Rhubarb, Blah, Blah" - hadn't a clue of course about tuning, just copied whatever method he'd come across presumably.
 
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