Question about bow poundage and arrow performance.

[PatM]

Yes but what poundage is that 50# bow performing at shooting the above standard speed of itself.

  50 pounds. The bow is just approaching the capability of a 50 pound bow. Bows that shoot slower at 50 pounds are underperforming.

[BowEd]

OK I see then.Marc and you have misunderstood what I've said and asked.In order for a 50# bow @ 60" long to shoot a standard arrow 190 fps at a mass weight of the bow @ 17.40 ounces it is not over built.It is performing above standard.

[BowEd]

I guess the proper way of describing a bows'capabilities is to not compare it's speed to the above standard speed it is shooting then.There is no correspondance there.Just that it is shooting a certain fps above it's standard.

[BowEd]

The reason it is shooting the arrow @ 190 fps is because of it's lower mass weight and it's design.

[Lumberman]

Beadman, I could be way off here but I thought you were asking if the velocity of the arrow say 700 grains, shot from the faster excellently built  (whatever you want to call it) 50 pound bow, the one shooting far above average fps for a 50 pounder, is essentially the same velocity as your efficient, average 70 lb bow flung arrow of 700 grains. If I am way off sorry lol

[BowEd]

Yes.Then would you say the 50# bow shoots like a 70#'er?I'm not looking for praise here.I'm my own hardest critic and am wondering where the claims and correspondance is here.

[BowEd]

Or say this 50 # bow shoots a 650 grain arrow @ 165 fps then is it shooting like a 65# bow?Etc. like that with that type of correspondance.

[BowEd]

Well ok then.It's like I've stated then.A 50# bow shooting a 650 grain arrow @ 165 fps is performing like a 65# bow.Guess I answered the question myself.Sorry for the misunderstandings.We all have goals of various types and passions along with them too.

[willie]

Ed

I am not aware of a "formula" that can be cited to help you out, but you could easily do that with a piece of graph paper and  bow testing with a chrony.



I am not suggesting that you undertake a survey and test project, but simply a way to record the specs of any bows that you make for your future reference.

If you plot velocity vs grains of arrow weight of a particular bow, yoiu should see a curve develop, that flattens on one end as the efficiency drops off. A bow with a different draw weight (but the same efficiency), plotted on the same piece of paper, will have a similar shaped curve alongside the first.

using the above example of plotting velocity vs arrow weight, will show differences of efficiency with differently shaped curves.

Plotting different metrics may give more easily comparable graphs. An possibility might be to plot grains/pound vs something else?

we often see force draw curves shown to "illustrate" a bows early draw weight and stacking, so why not  a second curve to show how the energy is released?

 willie

[Badger]

     Beadman, I think most of us understould the question fine. The problem with the question was that 150 fps was not a good place to start for comparision. You were starting at the bottom of performance levels instead of the average or closer to the top. If your 50# Bow shoots any arrow that a 70# bow shoots at the same speed it is performing as well as that particular 70# bow but it means nothing as some kind of standard.

    When you talk about dry fire speed it is exactly that dry fire. There is no point at which lowering arrow weight will quit increasing speed. If you add or subtract about 7 grains from an arrow it will affect your speed about 1 fps. The lower you arrow weight goes the more effect reducing arrow weight has. If Take 100 grains away from a 500 grain arrow I will pick up about 15 fps. If I take away 100 grains from a 200 grain arrow I will add about 100 fps.

[BowEd]

Yes I hear ya willie.All I really realize is what has been said or read through no findings of my own.I don't understand the process completely.Any way a chrono tells a lot and it's enough for now.

[willie]

Ed

if a guy kept some force vs draw readings from when he tillered a bow, and then shot various weight arrows through a chrony when he shot it in...

he would have a notebook with some comparable data, for future reference.....

guess I do it on a piece of graph paper because it helps "visualize" the numbers.

[BowEd]

I see.Well I have a little better idea about this.I appreciate your insight.The standard I was referring to is 10gpp draw weight arrow and I think a 3 gpp draw weight string too.Bows are a trip that for sure.Into the dark groping around for answers.....lol.

[BowEd]

Yes.A draw weight check every inch.Resting maybe 5 seconds between draws.

[DC]

To me that seems like an awful lot of book keeping and testing for little gain. Keep that phrase for bragging. "Yup, 50#, shoots like a 70". I guess though,you might be able to use the data for other things. Carry on