ORIGINAL: Arthur P

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.

ORIGINAL: TFOX

To be quite honest,I have NEVER seen the kind of results that MeanV has found and inTHEORY it can't,atleast in normal ranges.I do believe that once you reach a certain arrow weight,the ke will start to drop but it is well above the 650 grain mark imo.

BUT,it makes sense to me that if it is possible for a lighter arrow to absorb more of the bows potential energy(than normal)then ke will go up.For no other reason than speedhas increased more than it should.

So, I would be interseted in seeing some testing of the arrows in question.It would also make sense that the heavier arrow of the same material would show more normal findings and ke will not drop off from the 400 gr arrow to the 500 gr arrow.

443 grain arrow...302 fps... 90 foot pounds
502 grain arrow...283 fps... 89 foot pounds
625 grain arrow... 256 fps... 91 foot pounds

ORIGINAL: bigbulls

Ok, I had to weigh each component seaperately because my scale only goes up to 1650 grains. [8D]

Total arrow weight = 2084 grains.
Speed = 141 fps.
KE =92.02 foot pounds.

Here are the original numbers from the 82ndI shot a few days ago.
The KE level isn't climbing like all of the graphs and charts that Sylvan posted say it should. While the Ke level is a tad higher, I suspect that if I were able to keep going up in arrowweight the KE numbers would begin steadily falling. Any one have a 3000, 4000grain arrow laying around? No two bows are going to be the same when it comes to this kind of thing.

I suspect that the 82nd has a"hump" in the efficiency of thebow.I am sure it has everything to do with the cam design. But it still proves the point of "not always". There are far too many variables in how a bow performs from one to the next.

The momentum this arrow has is unbelievable. 1.31 lb/sec. It rocks a large 24 pound Magic Stop target like I have never seen and the bow, when fired, actually recoils into your hand like a gun would. And talk about a quiet bow.

Actually, with a high enough arrow mass, when releasing the string, the arrow would remain stationary and the only acceleration would be the bow accelerating backwards!

ORIGINAL: bigbulls

Yeah, It was just weird feeling a bow do that.

I haven't ever shot an arrow that heavy before and have never experienced a bow actually recoiling.

Nope, that couldn't happen. Haven't you been reading this thread? As the arrow weight increases, the KE of that arrowALWAYS goes up.

ORIGINAL: bigbulls

Yeah, It was just weird feeling a bow do that.

I haven't ever shot an arrow that heavy before and have never experienced a bow actually recoiling.

Nope, that couldn't happen. Haven't you been reading this thread? As the arrow weight increases, the KE of that arrowALWAYS goes up.

ORIGINAL: bigbulls
The KE level isn't climbing like all of the graphs and charts that Sylvan posted say it should. While the Ke level is a tad higher, I suspect that if I were able to keep going up in arrowweight the KE numbers would begin steadily falling. Any one have a 3000, 4000grain arrow laying around? No two bows are going to be the same when it comes to this kind of thing.

I suspect that the 82nd has a"hump" in the efficiency of thebow.I am sure it has everything to do with the cam design. But it still proves the point of "not always". There are far too many variables in how a bow performs from one to the next.

ORIGINAL: OHbowhntr

I can understand what you're saying, but he's shooting a 60# bow, not a 70#-er. I'd agree if it was a 70# 82nd, but being that he's shooting 60# it doesn't surprise me. Punching numbers out, my Trykon XL should achieve maximum KE with an arrow between 450-470grains, above that it drops off a touch and below that it drops off, according to number crunchers. I don't have the kind of money to buy a bunch of arrow and heads and shoot 25 gr variations from IBO to 600-650 grains, but it would be interesting if someone did just this with a bow and posted their results.