physics and Ashby

[enewman]

I see a few things I need to add or stress in my paper.

The paper is not about killing animals. or what it takes to kill animals.

The test was only to look at physics and to show that the statement by Ashby is wrong. Not that Ashby was wrong on the arrow part of it. He is correct. more mass better penetration. A broadhead that has less resistance to impact better penetration. I HAVE NEVER stated that was incorrect.

[Hardware]

Do you use a brand new piece of foam for each shot?
Do you always shoot the center most area of the foam?

[enewman]

Do you use a brand new piece of foam for each shot?
Do you always shoot the center most area of the foam?

he used a 4ft by 4 ft target. The shots were not in the center nor the same place.

I just got in my new targets. I will be also repeating his test. I didn't by the 4 ft targets. to **** much money. I will be marking the target so I don't shoot the same place. I will flip the target when changing the arrow's weight. This way I am not in the same place. I may also move around on the target to see if the banding of the target changes resistance.

I will shoot at least a 6 shot test. I then will run the ANOVA on it and look at the variables. If greater than 3 I will increase the sample rate till I'm below the 3. repeatability is key. For the test I was working on with sand I could not repeat the process. I scrapped the test.

I have also built a trolley to be able to measure travel distance. Im not sure I will do the test or if I do I will share. As I already know I will be beaten up because I will have friction in the bearings. As you can see by this post-testing is hard and people don't understand.

The trolley test should show the impact force. so as long as it is comparable or consistent then the friction truly will not matter. But it is a way for people that do not like the test or if it shows the opposite of what they believe it gives them an outlet to bash.

This is the same with using a target.

[lovemylegacy]

I see a few things I need to add or stress in my paper.

The paper is not about killing animals. or what it takes to kill animals.

The test was only to look at physics and to show that the statement by Ashby is wrong. Not that Ashby was wrong on the arrow part of it. He is correct. more mass better penetration. A broadhead that has less resistance to impact better penetration. I HAVE NEVER stated that was incorrect.

I think they are missing the point.

Appreciate the info and the non-combative debate. When you said Ashby was wrong, it kinda turned peoples world upside down. And I get that. I have read Ashbys material, so I get what he was doing and I get what you are doing. Unless Im mistaken, Ashby didn't use Physics formulas for his work. You are, thus the difference. When you went to Physics, weeeellll, that just left me waaaayyyy behind.

Keep up the good work.

[cbd10pt]

Where Ashbey stuff makes sense is in real world hunting situation.
A high FOC arrows penetrates better when the arrow is not on a perfect Straight path- just a little wobble and the friction is drastically increased.

Heavier arrow= slower speed=easier to achieve good flight.

If you can shoot straight under pressure, and keep your arrow off of heavy bones you are better off upping your FOC a bit and keeping a moderate arrow weight.

This is most easily achieved with a mechanical because higher speeds are harder to control.

Pluss whitetail move so speed helps.

Lots of variables in hunting.

Do you, have fun playing with different stuff- it's good for the economy

[Gunnyart]

Where Ashbey stuff makes sense is in real world hunting situation.
A high FOC arrows penetrates better when the arrow is not on a perfect Straight path- just a little wobble and the friction is drastically increased.

Heavier arrow= slower speed=easier to achieve good flight.

If you can shoot straight under pressure, and keep your arrow off of heavy bones you are better off upping your FOC a bit and keeping a moderate arrow weight.

This is most easily achieved with a mechanical because higher speeds are harder to control.

Pluss whitetail move so speed helps.

Lots of variables in hunting.

Do you, have fun playing with different stuff- it's good for the economy

This is why the Ashby 12 steps for penetration are so important. They work in concert beginning with mechanical integrity and perfect arrow flight. I want to take as many of the variables out of my hunting situation for my best chance at a complete pass through. It hurts me to watch hunting show where guys are getting 6" of penetration out a 4" diameter mechanical and celebrate what a great shot they made then sit for 6 hours before starting the recovery.

[98ag]

So you agree that a heavy arrow (within reason) with more foc is good but you disagree with how Ashby showed his work?

[enewman]

So you agree that a heavy arrow (within reason) with more foc is good but you disagree with how Ashby showed his work?

If we look at physics, there are things we need to look at.

Are we teaching physics correctly. Ashby did not.

We do not need Ashby to know that due to inertia and shot from same bow that a heavy arrow will increase penetration.

Back in the day bows where not as efficient. As we added arrow weight the bows transfer of KE was a big increase. So shooting heavy made a big change.

Let’s look at my xpedite. Between my 461gr and the 669gr I only had a 1.78% difference at the bow. And only a 6.86% at 50 yards. Not much of a increase. So, why would I ever shoot the 669gr over the 461gr. Only if you are a quarter too shooter or a leg bone hugger type shooter. Other than that why loose the trajectory.

These are the things we need to look at. Ashby studies where done on recurves. He tells you he couldn’t test compounds because he always got pass through so nothing was measurable.

As far as FOC. There is no data out there to show that FOC increases penetration with a compound bow with the correct spine or a stiffer spine arrow.

By the way, I have never stated that heavy won’t out perform.

[enewman]

So you agree that a heavy arrow (within reason) with more foc is good but you disagree with how Ashby showed his work?

Yes I disagree with how he showed what was going on.

[txchuck]

Sure enewman, you made it clear foam was used. It is at least a consistent material that will give you consistent results. As we all know a animal is anything but consistent, light or heavy bones, muscle, hair and movement of the animal can all affect penetration. As for arrows & arrowheads sharp and flying straight is the key.

[enewman]

Sure enewman, you made it clear foam was used. It is at least a consistent material that will give you consistent results. As we all know a animal is anything but consistent, light or heavy bones, muscle, hair and movement of the animal can all affect penetration. As for arrows & arrowheads sharp and flying straight is the key.

yes.

But the main point of this is not the test as much as Ashby stated KE has nothing to do with penetration and that two arrows of equal momentum but unequal mass the heavy will outperform. those two statements go against physics.

The problem we have is right now the Ashby foundation is telling people you need a 650gr arrow with 20% FOC and a single bevel broadhead to kill a deer.

we are already seeing people shooting this build taking shots that they would have never taken before. All because the foundation is telling them you can. we are seeing failures. people are posting this new build and don't understand why it's failing. People have gone from broadheads they were using that were working with good blood trails to this setup suggested by the foundation and are no longer getting blood trails.

This is an issue. people need to see what is going on. for some reason people are not speaking out. I am.

[cbd10pt]

Enewman.

Ashby's results are from hunting shots, FOC makes a big difference when there is a slight wobble in flight.
Wobble can start with form, grass, a twig, bone etc.

Think of your arrow as a lever, weight on one end multiplies the energy on the other end. You want weight on the front to correct what ever is going on in the light back end.

You're right FOC helps nothing in a perfect world, but bowhunting situation are usually not perfect

[enewman]

Enewman.

Ashby's results are from hunting shots, FOC makes a big difference when there is a slight wobble in flight.
Wobble can start with form, grass, a twig, bone etc.

Think of your arrow as a lever, weight on one end multiplies the energy on the other end. You want weight on the front to correct what ever is going on in the light back end.

You're right FOC helps nothing in a perfect world, but bowhunting situation are usually not perfect

If you have any data or testing that FOC improves penetration for a compound bow, I would love to see it.

This is written by ashby explaining why FOC works and how to test. Notice he tells you we can test this in a foam target. I have seen this test. It showed no increase with a compound bow.

"Ashby""The lower inertial mass of these Ultra-EFOC shafts also
means that there will be less total shaft flex at impact. Shaft
flex has been shown to be a major factor in arrow penetration.
This is easily demonstrated. Using a well tuned arrow having
Normal FOC shoot several arrows into a new foam target at very
close range, say 2 or 3 feet, and measure the average
penetration. Now shoot those same arrows into the same target at
15 or 16 yards. Though they will have lost some velocity (and
force) the arrows shot at the longer range will show greater
penetration. This is because the Normal FOC arrows are still in
extreme paradox at the close range; they are flexing to a
greater degree than they are at the longer range. The greater
shaft flexion increases the resistance to penetration. Their
lesser degree of shaft flex at impact is the predominate reason
Ultra-EFOC arrows show such an astonishing degree of gain in
post-breaching tissue penetration; compared to comparable arrows
of Normal, High and Extreme FOC."

that is in the 2008 updates.

Funny story. I posted that on Facebook but I left Ashby's name off of the post. I was attacked. told me I was stupid. I had no clue what I was talking about. Now, this post was on an Ashby site. where everyone says we know Ashby studies inside and out. one of the members that states I was an idiot was a foundation officer. Then it was reposted with Ashby's name on it. the amount of backing up was unbelievable. Very few people have a clue what is in the Ashby reports. People just regurgitate from people they think that has the knowledge. I showed where even an officer of the foundation. The person that claims to be Ashby's right-hand man didn't even know it was there.

I have no issue with building arrows with FOC. I cannot hurt until you reach a point that the arrow is too stable and we have issues. But it takes a lot of FOC to get there. I didn't see this problem till 29% (flight only) because I shoot light gpi shafts and I normally shoot 200gr broadheads and I like around 450plus for TAW I always have high FOC.

[enewman]

Let's look at how Ashby skewed the test. In this test, he is showing increasing FOC by a small percentage gives us a significant increase in penetration.

Let's not forget how to show an increase.

Increase = (final-inital)/initial

Ashby would have used the correct equation as he did throughout all of his papers when showing an increase in penetration. Then it would have shown that it takes a lot of FOC increase to get such a small gain.

He is telling people that going from 10.3 FOC to 25.7 is an increase of 13.4. that is not correct. That is a change, not an increase. That is a 149.5% increase.

[enewman]

Stop shooting bone.

Ashby "Earlier testing with arrow sets matching in all aspects
except FOC has shown that from 19% FOC upwards there is a
measurable gain in arrow penetration. There is now sufficient
comparative data between Normal FOC, EFOC and Ultra-EFOC arrows
to make some observation about the degree to which increasing
FOC affects outcome penetration, at least for shots impacting
heavy entrance-side bone.
Some may wonder why a comparison of Normal, Extreme and
Ultra-EFOC arrow penetration in soft tissue is not also being
done. That answer is really simple. The penetration enhanced
EFOC and Ultra-EFOC arrow setups have demonstrated exceedingly
high levels of soft tissue penetration; so high that an allsoft-tissue target many feet thick would be required to even
begin the process of quantifying results"