physics and Ashby

[enewman]

I think the important question to ask is: does more foc weight cause an arrow to fly straighter?

FOC. no FOC DOSENT. FOC is a static measurement to show you how much weight of the arrow is in front of the center given in percentage.

But if we look at what it really is we need to look at the center of gravity and the center of pressure and the static margin.

When we add weight or take it a way we move the center of gravity location. Does this change arrow stabilization. Yes but it’s doing this because we are changing the static margin between the center og gravity and the center of pressure. So the location of the center of pressure is what is doing the stabilization.

Now for most including me it’s just easy to use FOC. It’s a easy calculation for everyone to use.

[enewman]

Can’t argue with results….


[emoji1662]

We can argue the results. We are now seeing people kill elephants, hippos, and Cape buffalo with sub 600gr arrows. Ashby could not get these results. Why, because he tested with low energy set ups.

Let’s not forget Ashby stated on a podcast that he could not test with compound bows because he always got a pass through. He had no measurable data. That statment alone should trigger people into understanding what it takes to kill with a trad bow is not what we need to kill with a compound bow.

[diamond10x]

I can see you do not know joel maxfield. Look him up. When you do you may need to type in joel maxfield with Mathews.

Your question will be answers.

These test that I’m showing, are some I am working on. I am fixing tod a NEWTONIAN and NON-NEWTONIAN test.

Your question about same bow. No. You cannot test equal momentum doing this. Reason is thee is a big KE difference.

I have people tell me you cannot do a test like this, because I am changing bows. That normally comes from the ashby crowed. Funny thing is they seem to forget that ashby tested and compared to each other with a 40,54,70, and a 82 lb bows.

Funny is it was ok for ashby but not me. The difference is I’m showing different results and I using physics to support my test. Ashby did not.

Also a bow is just a machine. It’s purpose is to convert the energy you put in to drawing the bow into potential energy then convert it back to kinetic energy and transfer that energy to the arrow so the arrows has acceleration.

This is why I use a term I coined. K.E.D.D. kinetic energy delivery devise. That is all a bow is.

Ranch fairy calls it a kinetic energy spring. He is doing this I assume for the same reason I did. To show people when testing it doesn't matter what bow we use to reach what is needed to test.

I could care less who maxfield, Ashby, or ranch fairy are just so we’re clear I’m not on anyone’s side. If you aren’t testing things out of the same bow or ,KEDD as you prefer, then you’re not comparing apples to apples. No matter who the tester is that is not a halfway sound experiment, it’s fishing for results to fit a narrative.

I could take an arrow from each end of the spectrum and make them out perform each other in ways that half the people would argue with and the other half would agree with.

All I know is I’ve witnessed real world results between what ~385gr arrows will do hitting bone vs ~500gr arrows. That cannot be argued.

[BernieH]

All you've done is compared kinetic energies of the two arrows with the lighter faster arrow having more kinetic energy.

Two more appropriate analysis would be to look at the situation from a conservation of energy perspective. In this analysis you'd take into account energy spent penetrating which would be greater for the faster arrow since the resistance a faster arrow would see is exponential to it's velocity. The other way it could be looked at is from a conservation of momentum perspective where you include the impulse to stop the arrow. In the momentum analysis you'll see that the impulse force the slower arrow sees is less (sees less resistance). The issue with this analysis is that arrow penetration is not an elastic collision.

Neither of these analysis is perfect since there are unknown variables involved.

[enewman]

I could care less who maxfield, Ashby, or ranch fairy are just so we’re clear I’m not on anyone’s side. If you aren’t testing things out of the same bow or ,KEDD as you prefer, then you’re not comparing apples to apples. No matter who the tester is that is not a halfway sound experiment, it’s fishing for results to fit a narrative.

I could take an arrow from each end of the spectrum and make them out perform each other in ways that half the people would argue with and the other half would agree with.

All I know is I’ve witnessed real world results between what ~385gr arrows will do hitting bone vs ~500gr arrows. That cannot be argued.

then you don't understand testing. That is ok. most do not.

By the way, if you could care less then why are you on my post. hahahaha

as far as in the real world. the 500 will outperform the 385 all day every day. no one is disputing this.

as far as you saying I'm not comparing apples to apples. this alone shows me you do not understand. I did compare apples to apples. Momentum is equal. that is apples to apples.

[enewman]

All you've done is compared kinetic energies of the two arrows with the lighter faster arrow having more kinetic energy.

Two more appropriate analysis would be to look at the situation from a conservation of energy perspective. In this analysis you'd take into account energy spent penetrating which would be greater for the faster arrow since the resistance a faster arrow would see is exponential to it's velocity. The other way it could be looked at is from a conservation of momentum perspective where you include the impulse to stop the arrow. In the momentum analysis you'll see that the impulse force the slower arrow sees is less (sees less resistance). The issue with this analysis is that arrow penetration is not an elastic collision.

Neither of these analysis is perfect since there are unknown variables involved.

yes because KE is involved. but the test was looking at physics and that two arrows of qual momentum but unequal mass. As I have already stated the test and physics were based on Ashby stating equal momentum.

the reason the lighter arrow wins is because of KE again Ashby states that ke has nothing to do with penetration. This physics test shows that Ashby was incorrect with both his statements.

I could have shown how much force was spent. I actually had all of that in the chart. but I was afraid it was to much. as we can see even what I did is to much.

[muddyfuzzy]

We can argue the results. We are now seeing people kill elephants, hippos, and Cape buffalo with sub 600gr arrows. Ashby could not get these results. Why, because he tested with low energy set ups.

Let’s not forget Ashby stated on a podcast that he could not test with compound bows because he always got a pass through. He had no measurable data. That statment alone should trigger people into understanding what it takes to kill with a trad bow is not what we need to kill with a compound bow.

To each is own but I would never recommend to anybody that they should hunt dangerous game with less arrow than needed. You are going down a rabbit hole here that is ill advised. Forget about Ashby, FOC and all that stuff. I’ve spent time in Africa, no reputable outfitter would ever recommend what you are proposing. It’s dangerous, negligent and just plain silly. If a guy thats seen hundreds of Buffalo taken with archery equipment he’s probably on to something. My guys wouldn’t let you out of the truck with a sub 600 grain arrow chasing Buff, just because you can doesn’t mean you should. There is just too much historical data showing what works and what doesn’t with Buff, I don’t know anybody that’s doing what you are stating and again anybody with any seat time in the Bush that would recommend it.


[emoji1662]

[diamond10x]

then you don't understand testing. That is ok. most do not.

By the way, if you could care less then why are you on my post. hahahaha

as far as in the real world. the 500 will outperform the 385 all day every day. no one is disputing this.

as far as you saying I'm not comparing apples to apples. this alone shows me you do not understand. I did compare apples to apples. Momentum is equal. that is apples to apples.

[enewman]

To each is own but I would never recommend to anybody that they should hunt dangerous game with less arrow than needed. You are going down a rabbit hole here that is ill advised. Forget about Ashby, FOC and all that stuff. I’ve spent time in Africa, no reputable outfitter would ever recommend what you are proposing. It’s dangerous, negligent and just plain silly. If a guy thats seen hundreds of Buffalo taken with archery equipment he’s probably on to something. My guys wouldn’t let you out of the truck with a sub 600 grain arrow chasing Buff, just because you can doesn’t mean you should. There is just too much historical data showing what works and what doesn’t with Buff, I don’t know anybody that’s doing what you are stating and again anybody with any seat time in the Bush that would recommend it.


[emoji1662]

I would never recommend either.

Its funny how all Im doing is showing physics and you think Im promoting light arrows. come on muddy. I know you are smarter than that.

[enewman]

All you've done is compared kinetic energies of the two arrows with the lighter faster arrow having more kinetic energy.

Two more appropriate analysis would be to look at the situation from a conservation of energy perspective. In this analysis you'd take into account energy spent penetrating which would be greater for the faster arrow since the resistance a faster arrow would see is exponential to it's velocity. The other way it could be looked at is from a conservation of momentum perspective where you include the impulse to stop the arrow. In the momentum analysis you'll see that the impulse force the slower arrow sees is less (sees less resistance). The issue with this analysis is that arrow penetration is not an elastic collision.

Neither of these analysis is perfect since there are unknown variables involved.

here is a test looking at the work energy using a foam test media. It to is quantified by physics. It this what happens in an animal. don't know as animals are not good test media if looking at physics.

dr Ashby was very smart when he stated I'm using a non-scientific outcome-driven test.

The test was not to see what we can do when hunting animals. it was to look at physics to see if the statement made by Ashby about equal momentum was correct. as you can see it wasn't. This is an issue in the archery world. people are being taught the physics of archery by people that read Ashby and it is WRONG.

here is looking at the force with matching KE. as you can see the net force between the two is equal. This would be that the equal momentum the heavy arrows force would be less.

Not sure why you brought up elastic collision. we know its not as the arrow is loosing energy

[enewman]

Looking at the net force with equal momentum with a physics test into a foam target.

The question is why did it take less net force to stop the heavy arrow with equal momentum. The heavy arrow had less KE. Meaning it could not do the same amount of work. AGAIN I am only looking at the physics aspect of it. based on Ashby's statements.

As you can see he was wrong on the physics part. not what the arrow can do.

[Duckologist]

I think the important question to ask is: does more foc weight cause an arrow to fly straighter?

No, your tuned bow will cause your arrow to fly straighter

[Duckologist]

Looking at the net force with equal momentum with a physics test into a foam target.

The question is why did it take less net force to stop the heavy arrow with equal momentum. The heavy arrow had less KE. Meaning it could not do the same amount of work. AGAIN I am only looking at the physics aspect of it. based on Ashby's statements.

As you can see he was wrong on the physics part. not what the arrow can do.

So do you think that if you used a broadhead and say a deer instead of foam that your results would be different? Are the two arrows being shot into the foam the same diameter?

[enewman]

I was told that I needed to explain better.

First, the test is a physics test. It was to look at what physics tells us, and I compared it to what Ashby stated. With physics, I showed that he was wrong. Not as what he did but what he is teaching that gives us penetration.

Now, as far as arrows. Suppose we shoot from the same K.E.D.D. Then the heavy arrow will out penetrate. We know this. We know this because physics tells us this.

I do not promote light arrows. I promote what works for you. If you are killing with a 425gr arrow, then there is absolutely no reason to change. When people come to me and state, the 425gr failed. my first question is not about mass (Dr. Ashby #6 in the penetration factors); I ask about what broadhead (#4 in the factors)

Ashby's studies are with low energy. He did this because he tested with high energy, and the arrows always passed through. No way to get measurements. That alone should tell you there is a point where a lighter arrow with the correct amount of Ke will perform just as well as a heavy arrow. We just do not know where that is.

[Duckologist]

my first question is not about mass (Dr. Ashby #6 in the penetration factors); I ask about what broadhead (#4 in the factors)

My first question would be did you tune your bow or did you let the shop "tune" it?