I am simply telling you exactly what the chronograph reads.No, it's not perfect but by doing thisthere should beeither adrastic increase or decrease in KE. If what Sylvan says is true then the KE from an arrow weighing a few thousand grains should be off the charts.

I don't have the time, energy, or money to make this perfect. If someone else has the time and moneyto conduct an absolute perfectly controled test then please do.



In the typical bow force graph below (used from huntersfriend.com)the draw force curve on the left is the bows input energy, or the ammount of energy it takesa person to pull the bow to full draw.On the right is the bows output energy. A bow only stores a specific amount of energy. Sets say that the shooter puts 100 pounds of energy into getting the bow to full draw. That represents the area under the blue line on the left.The bow will store that energy but the output energy will be less due to friction. Representedby the area under the red line.For arguments sake lets say the out put energy is 95 pounds (5% lost to friction).

To use an extreme example if an arrow weighed exactly the same as the amount of energy that the bow was capable of applying tothatarrow then the bow would not be able to accelerate that arrow and the arrow would have zero KE.

This example is obviously way on the side of diminished returns but it illustrates the point perfectly.

I am not claiming anything. Just reporting the facts

You might need to do more testing yourself instead of so much reading[8D]

My 82 can't read

Dan

Check out bigbulls findings on the same model Bow. Interesting to say the least. All arrows were as close in spine as possible in my tests. I know the mags don't tune for every different arrowsetup.

Dan

This statement displays a complete lack of understanding of the physics envolved in launcing and arrow from a bow.

In one sentence, you confuse energy with force, you confuse weight and mass,and you imply that it is force acting against a forcethat explainsacceleration. Nice job! You really think that 1 pound of force won't accelerate a mass that weights 2 pounds. Lol. You, my friend are way out of your element.

Yes you are. You claim that it's a fact that you can go to a heavier arrow and the resulting kinetic energy will go down.

It also follows from that claim that a bow will shoot 2 arrows of different mass yet have identical kinetic energy.

Well Mr. Sylvan, you think ArthurP, bigbulls, and I are internet nobodies? Over 100 years experience shooting, testing, and working on Bows.

LMAO!!

Please introduce yourself. How many years have you been testing bows? For that matter how many years have you been flinging arrows?

We all know you can read[8D]

Again you seem to avoid the fact that what I posted was actual figures from tests I ran on my 82. It is amazing how bigbulls figures mirror mine. I guess neither of us can read a chrono or figure KE. I also stated this is not the norm. See my figures on my General and Guardian.

KE will NOT ALWAYS increase with arrow weight it is proven. You are welcome to come over and disprove it if you like[8D]

Dan

Yes, of course you are. Just as everybody else is here including myself. Does it matter? I could bore you with my qualifications but what I am or how much experience I have is NOT a technical argument. Your experience isn't either. You guys experience just goes to show that a person can be wrong for a long long time.


You haven't proved anything. In science one begins with observations. You've done that, you claim to have made observationsthat increasing arrow weight reduced ke. From observations you develop theory to explain those observations. You haven't done that and even what you tried to explain was jibberish. Then you submit your paper which should include your theory and your observatons for independent scientific review. You haven't done that. Then independent testers try to duplicate your results and coroborate them. In time your theory becomes accepted by the scientific community and though nothing is totally proved in science but only tentatively accepted, your theory rises as the best explanation of the phenomenon we have so far.

All the above has been done for what I have tried to explain to you i.e. kinetic energy increaes with arrow mass.

You are again an internet nobody with a couple of observations that go contrary to accepted theory and jibberish for a theory as to how it happens. Indepent professional testing labs support accepted theory and fail to duplicate your results.


I'm truly becoming bored with you guys now. If Isee anything worth commenting on I might stop back, but I doubt it will happen.

You guys have fun pretending to be scientists and engineers.

Ok, lets hear it? I would not be bored hearing your qualifications as a scientist or engineer. Maybe it blows me out of the water. Who knows. Lets hear what you got.

You spend enormous amount of time and energy (like loser time, if you know what I mean)trying to prove your right on the internet to people you referr to nobodies, and people I would love to meet, shoot with, hunt with, and befriend. You have none of those desires with these people. This is very obvious.

So you got to ask yourself in the end, what does that make you? Sure, I snipe and jab, but you are not going to see me invest research, or a whole lot of time trying to the "internet man" unless it puts moneyin my hand, or food in my stomach.I many even embarrass myself on here as you say, and in the end, it doesn't matter in the real world. So who's the joke on, on this thread?

I know there is a point where arrow mass will exceed a bow's capacity to shoot efficiently, but I would expect it to be far heavier than Mean V's results show. I have to look at the data though, and look at it with an open mind.

MeanV says his bow shoots a 500 gn arrow with less KE than it does a 400 gn arrow. Yes, the results are odd, it seems way too light of an arrow to show a dropoff. But that's what his testing shows. Was it an aberration? Would KE have gone back up if he'd gone further and shot a 600 gn arrow? I don't know. He didn't test and we have no hard data to prove otherwise. I certainly have had my disagreements with the man, but I respect him enough to take his test results seriously.

This is not the first time I've heard of this happening though. I've had similar reports from several other knowledgeable people in the past 5 years or so; different bows, different manufacturers. I think perhaps the manufacturers are building designs nowadays that are more efficient at shooting arrows weighing 350-450 grains because of the mass stampede to carbon arrows. That is the weight range most people are shooting these days, and naturally they all want to put out those high IBO ratings to get people to buy their bows. I think it's just possible that loading up efficiency on the low end of the weight scale has the effect of sacrificing efficiency for heavier arrows. It's the only logical conclusion I have for a KE dropoff with arrows as light as 500 grains, but I've not yet seen the whole picture.

You see, unfortunately, in each case the shooter did what Mean V has done. Once he saw the KE drop for an arrow weight, he didn't go on to test an even heavier arrow. So we're still in the dark as to whether the drop was only for that particular weight and would have risen for a heavier arrow, if it was the beginning of a downward trend in KE. More testing needs to be done. Until someone does it though, we don't have enough data to draw any firm conclusions.

Another small point... When looking at bow test data, keep in mind that the KE/arrow weight graphs have not been drawn up with hard data for every arrow weight shown. As noted earlier, it's darn difficult to test a wide variety of arrow weights without needing to do some serious retuning for different arrows. If you read the fine print, what most often happens is the tester has used 2 different arrow weights (usually 5 gpp for IBO and 9 gpp for AMO) to establish a line on the graph, and the KE figures for all other arrow weights are extrapolated off that line. Line graphs are handy tools for making estimates, but hard data from actual testing trumps estimates, every time.

This is all quite interesting, in a macabre sort of way. I have said the following in this thread before, but here it goes again. The statement that KE ALWAYS goes up with increasing arrow mass is, by definition, invalid. The equation from which all else follows in the context of this argument is

F = ma (force = mass x acceleration, elegant in its simplicity eh). Once a modern bow has the draw weight set, the force it can deliver to the arrow (via the string) is, for all intents and purposes, a constant. As such, the only variable in our control is mass (of the arrow). Changing the mass (of the arrow) changes the acceleration (again, of the arrow). Since a = F/m, the instant the mass of the arrow increases from zero the system is on a collision course to acceleration of the arrow becoming zero – there is no escape. Since velocity is a direct result of acceleration [a = (vf – vi)/t], if the acceleration goes down, so does velocity. Now, since KE = ½ mv^2, if velocity goes down, KE goes down (goes down exponentially at that). As such, the statement that KE always increases with increasing arrow mass is, by definition invalid. This is not Los Alamos particle accelerator physics. It is ninth grade, physical science physics. This is not a point of conjecture nor is it a guess. It is physics, as physics is currently understood (although that does tend to be a dynamic argument).

I also did a simple calculation regarding the comparison of Kinetic Energies of arrows. I did the calculation with a 400-grain arrow and a 500-grain arrow as they were so heatedly debated. The math is a simple calculation that comes from stating the KE of a ‘light’ arrow is greater than the KE of a ‘heavy’ arrow, then solving the inequality for the velocity of the light arrow. That inequality is:

V(light arrow) > root m (heavy arrow) divided by root (light arrow) times velocity (heavy arrow). What that inequality states is that if the velocity of the light arrow is the product of the square root of the ratio of the mass of the heavy arrow to the mass of the light arrow times the velocity of the heavy arrow, then the ‘light’ arrow will have more KE than the heavy arrow! In the case of the 500-grain/400-grain arrow comparison, the 400-grain arrow will have more KE than the 500-grain arrow if the velocity of the 400-grain arrow is (root 5)/2 times greater than the velocity of the 500-grain arrow, period, no ifs ands or buts about it!. That statement is not a function of tune of the bow, or spine of the arrow. A ‘light’ arrow with root 5/2 times the velocity of a ‘heavy’ arrow can be flying sideways or turning cartwheels on its merry little path, it will have more KE than the ‘heavy’ arrow (which can also be doing aerial gymnastics as well). The math behind that argument is not integral calculus or Diff. Eq., it is good old friendly ninth grade algebra. If you don’t believe me, then as one of my college professors stated, “Do the math! Do the G.D. math!”