Arrow. Weak/stiff. My take

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Question since y'all see to know what y'all are talking about. I have a Hoyt Charger now and it shows to be about 325 fps at 70lbs. I will probably set it about 63-65 pounds. It is a Cam and a half system. I am tall so I shoot a 29.5 draw length. I am about to get some arrows cut in the next week but have been scratching my head around which arrow will be best for me. I would like to shoot a 100 gr broad head fixed or mechanical. I want to try both. I had heard from someone that if I shoot a longer arrow it might be a good idea to shoot a heavier arrow set up so that I get less flex and will fly a little truer. Thoughts? I have noticed in the past with some cheaper Cabelas arrows, $69 a dozen, I could see the arrow flex in air. I switched to some Eastons and had better results. I just want to get a good starting point for which arrow might be best for my set up.

A longer arrow will be the equivalent of a "weaker" spine. This has to do with the ball analogy from above. A longer arrow will have a weaker reaction than a shorter one. The key is to figure out what you want your finished arrow weight to be, along with your desired foc range and build from there. I like to cut my arrows 1/2" longer than my draw length, simply because I like the BH to clear the riser at full draw.

[enewman]

Interesting question. I have been shooting CX Pile Driver Hunter 350 cut to 27" with a 28" dl and 65# dw 125 gn tip from both a Hoyt NT and PSE Prophecy. Avg arrow weight is 479 gn. This arrow seems to fly and group better for me from either bow than say a Gold Tip XT 340 or even Easton Bloodline.

So now my question is are heavier arrows better to shoot than light ones? Mine appear to be.

If the spine is the same on different arrows, but one brand is 9.5 gn per inch and the other is 8.5 gn per inch. Even with them being say a 350 spine the dynamic reaction will not be the same. This is why we see some shoot better then others. You will see the difference if all same between good arrows vs cheep arrows.

[enewman]

The reason this testing method cannot be 100% is because it tests perpendicular to any stress exerted on a shaft.
Testing also does not factor the fact that larger OD shafts are inherently stiffer than same material and weight in a smaller diameter. A better test could be a compressive load concentric to centerline with a dial indicator measuring flex at a given load. This could also prove what side of arrow is stronger.

Can you explane what your saying on the testing.

[WKH2213]

I have found in my testing that the DCA arrows, while being rated the same spine as Bloodsport, CX, and Black Eagle (all three made in same china plant), tend to be much stiffer and shoot better for me.
The DCA 350 has the same flex stiffness as a Bloodsport 300.
Just my findings

[Limbwalker]

Can you explane what your saying on the testing.

He's talking about column loading which is essentially what the bowstring does to an arrow, as opposed to the lateral bending caused by the arrow supporting a 1.94# weight between a span.

http://www.thecartech.com/subjects/m...n/Buckling.htm

[Limbwalker]

But don't the nodes really come into play when we look at the effect the string has on the arrow, particularly as the arrow bends left and right as it is being launched. From what I have gathered that is the whole reason people paper tune. If the spine isn't correct for the upfront weight the arrow has to flex more to overcome the static inertia of the tip. The flexing back and forth doesn't stop instantly as he arrow moves forward, it continues for several feet wobbling back and forth. And these "nodes" are not necessarily at equal/same distances for different bows and arrows.

Or am I totally wrong?

The nodes are always there, every shot, every arrow, every condition. The stationary points on the shaft when the ends of the arrow bend left and right (and the center of the arrow bends the opposite direction) are the nodes.

This is just like a guitar string that is plucked, the middle of the string is traveling in the opposite directions from the ends, and the nodes never move.

The flexing, or oscillation continues all the way to the target.

https://www.youtube.com/watch?v=CO102jz8sFM

[Limbwalker]

For a finger shooter, nearly all the flex will be in the horizontal plane. For a release shooter using a rest that supports the arrow from below (lizard tongue or drop away) the flex will be in the vertical plane. But they all flex.

The compound/release is just much more forgiving of different spines than a finger-shot arrow. You can tune a wider range of spines from a release shot bow so choosing the exact right spine isn't quite as critical - but there is still a sweet spot.

However, it's tough to overspine a compound shot with a release, so it's always better to err on the side of too stiff. I could get easily shoot 400 spine arrows from my compound, but I use 340 spine for this reason.

[enewman]

He's talking about column loading which is essentially what the bowstring does to an arrow, as opposed to the lateral bending caused by the arrow supporting a 1.94# weight between a span.

http://www.thecartech.com/subjects/m...n/Buckling.htm

you said people's eyes are glazzing over when talking about nodes. But you just said columns. Haha.

I think he miss read what I was doing. When testing static all I was doing was matching spine. And showing that people think if they cut the arrow they are making it stiffer in a static position. This is not correct.

By cutting you are changing the dynamic reaction. Which makes the shaft show a reaction that is either stiff or weak depending on tip weight knoc weight draw length arrow length

In this post I was not looking or talking about the static stiff point or the dynamic stiff/neutral plane. That can or cannot be found by a static tester.

To find the best dynamic spine, and set up is to shoot.

Now the column. I've looked at this. I'm not 100% I see this. I see why they may call this a column. But a column is vertical. And a shaft is horizontal. Now this may be true as an engineer prospective. But now you are really going to have a hard time convincing the archery world we are shooting columns and not arrows.

[enewman]

The reason this testing method cannot be 100% is because it tests perpendicular to any stress exerted on a shaft.
Testing also does not factor the fact that larger OD shafts are inherently stiffer than same material and weight in a smaller diameter. A better test could be a compressive load concentric to centerline with a dial indicator measuring flex at a given load. This could also prove what side of arrow is stronger.

I've looked at this. To put equal amount of pressure at both ends of the column. Now we would have to calculate how much pressure it would require compared to the draw weight of the bow your shooting. You would also have to calculate how much stroke would be needed in the compression.

Now could we measure with an indicator. Sure. But at that point your making a static reading not a dynamic reading.

Now can we compress the column and find the stiff point in the column yes and no. It's not 100%. .001 arrows can and will not all ways bend in the same point. A .006 most of the time it will. And it well flex on the run out of the shaft.

So again. To find if you have the best dynamic reaction required for you and your set up is to shoot it.

[rocky]

For a finger shooter, nearly all the flex will be in the horizontal plane. For a release shooter using a rest that supports the arrow from below (lizard tongue or drop away) the flex will be in the vertical plane. But they all flex.

The compound/release is just much more forgiving of different spines than a finger-shot arrow. You can tune a wider range of spines from a release shot bow so choosing the exact right spine isn't quite as critical - but there is still a sweet spot.

However, it's tough to overspine a compound shot with a release, so it's always better to err on the side of too stiff. I could get easily shoot 400 spine arrows from my compound, but I use 340 spine for this reason.

Arrow selection can't be explained much better than this.
A person can complicate this simple process, with the only outcome being, (this arrow 'seems' to shoot better).

[BTLowry]

I can always hit the equipment section for something to make me think and/or educate me

Thanks to all who TRY and make the rest of us understand how this all works and how we can improve our shooting and performance of our equipment

[rocky]

I can always hit the equipment section for something to make me think and/or educate me

Thanks to all who TRY and make the rest of us understand how this all works and how we can improve our shooting and performance of our equipment

I like all these threads like this.
Good reads.

[Limbwalker]

you said people's eyes are glazzing over when talking about nodes. But you just said columns. Haha.

I think he miss read what I was doing. When testing static all I was doing was matching spine. And showing that people think if they cut the arrow they are making it stiffer in a static position. This is not correct.

By cutting you are changing the dynamic reaction. Which makes the shaft show a reaction that is either stiff or weak depending on tip weight knoc weight draw length arrow length

In this post I was not looking or talking about the static stiff point or the dynamic stiff/neutral plane. That can or cannot be found by a static tester.

To find the best dynamic spine, and set up is to shoot.

Now the column. I've looked at this. I'm not 100% I see this. I see why they may call this a column. But a column is vertical. And a shaft is horizontal. Now this may be true as an engineer prospective. But now you are really going to have a hard time convincing the archery world we are shooting columns and not arrows.

The Easton spine test (deflection in inches of a 28" span supporting a 1.94# weight) is a static spine test. Column loading would be a dynamic spine test, if we could do it for a particular arrow. It matters not whether a column is in the vertical or horizontal plane. It only matters the amount and direction of the forces that are acting on it. In a vertical plane, gravity is the force that acts on the column. In a horizontal, the bowstring is the force that acts on the column (arrow).

Thankfully, we don't have to have either of these things since we can simply shoot an arrow without fletching and see the results in the air.

[enewman]

The Easton spine test (deflection in inches of a 28" span supporting a 1.94# weight) is a static spine test. Column loading would be a dynamic spine test, if we could do it for a particular arrow. It matters not whether a column is in the vertical or horizontal plane. It only matters the amount and direction of the forces that are acting on it. In a vertical plane, gravity is the force that acts on the column. In a horizontal, the bowstring is the force that acts on the column (arrow).

Thankfully, we don't have to have either of these things since we can simply shoot an arrow without fletching and see the results in the air.

Yes just shoot , but. I've done some research on the column. I didn't get real deep. But Etheis on the form has. And I may get back into this.

One of the thinks I see is when testing a column. Is the test has the column fixed or pined at both ends. When enough force is applied it will buckle. An arrow is only fixed at one end. The knoc.

So an arrow once shot is being compressed for that split second. But once the arrow leaves the bow the compression is no longer there. So the arrow will recover. Buckle will go away. This is a dynamic reaction. Lot of veribles. All can be calculated.

At this time I'm not sure the dynamic test of a column is the same as dynamic reaction of an arrow. Same word(dynamic) but used for to different things.

But maybe I can see this. I maybe looking at it with to much time. I need to shorten my time frame down. Look at it at the point of release and max flex of shaft then stop at that time frame before arrow has left the bow.

Lease just over look my rambling. I'm thinking at the same time I'm texting. So I'm evolving on the thought.

I will assume that the formulas for finding this is the same ones used in the spine programs.

[Limbwalker]

An arrow is only fixed at one end. The knoc.

That's how it would appear. However the mass of the point weight serves as a fixed point until inertia is overcome by the force of the load. You know, that whole "objects at rest want to stay at rest" thing. That is why the arrow buckles. Because the mass of the point is resisting the load that the string is putting on the other end of the column.