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speed or kinetic energy?

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I just turned my bow down in poundage and now have a choice of two spines. The difference in the two is around 50 grains on finished arrow weight. I can shoot the heavy arrow at 260fps with about 60 ft/lbs of energy or the lighter arrow at 272 fps with a shade over 56 ft/lbs. of energy. Which route should I go or does it really matter? I should also add that arrow flight is good with either.:confused2:
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I personally would go with the heavier arrow but that's my personal choice, either would be fine.

I like the heavier arrow because I believe it penetrates better and makes the bow more quiet. (I'm assuming this is for hunting). If it's for 3D I'd shoot the lighter arrow 'cause neither of the aforementioned reasons are important. Don't think there is a 'wrong' answer here.

hd
 

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I can shoot the heavy arrow at 260fps with about 60 ft/lbs of energy or the lighter arrow at 272 fps with a shade over 56 ft/lbs. of energy. Which route should I go or does it really matter? I should also add that arrow flight is good with either.:confused2:
The speed difference isn't that great; I would use the heavier arrow.
 

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Which one

I personally would go with the heavier arrow but that's my personal choice, either would be fine.

I like the heavier arrow because I believe it penetrates better and makes the bow more quiet. (I'm assuming this is for hunting). If it's for 3D I'd shoot the lighter arrow 'cause neither of the aforementioned reasons are important. Don't think there is a 'wrong' answer here.

hd
Very nicely stated :star:
 

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Discussion Starter · #5 ·
hunting only

This set up is for hunting only. I am right on the line as far as which spine I need so I will probably end up with the heavier spine so I will still be good if I decide to turn my bow back up.
 

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I personally would go with the heavier arrow but that's my personal choice, either would be fine.

I like the heavier arrow because I believe it penetrates better and makes the bow more quiet. (I'm assuming this is for hunting). If it's for 3D I'd shoot the lighter arrow 'cause neither of the aforementioned reasons are important. Don't think there is a 'wrong' answer here.

hd
There is a "right" answer here, and this is it ^
 

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As long as the arrow is heavy enough and sharp I don't see why speed wouldn't be the answer? :darkbeer:
 

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I just turned my bow down in poundage and now have a choice of two spines. The difference in the two is around 50 grains on finished arrow weight. I can shoot the heavy arrow at 260fps with about 60 ft/lbs of energy or the lighter arrow at 272 fps with a shade over 56 ft/lbs. of energy. Which route should I go or does it really matter? I should also add that arrow flight is good with either.:confused2:
You might want to check your math.....seriously arrows that close in weight and speed should not show a difference of 4 ft/lbs......where are you getting the results from?

A bow will typically vary less than 5% KE from the minimum 5 g/p/p all the way to about 10 g/p/p. having that much diffence with only 1 g/p/p is not normal or usually accepted.
 

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I will probably end up with the heavier spine so I will still be good if I decide to turn my bow back up.
Bingo!:thumbs_up That would be my choice as well.
 

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Discussion Starter · #10 ·
The math don't lie

You might want to check your math.....seriously arrows that close in weight and speed should not show a difference of 4 ft/lbs......where are you getting the results from?

A bow will typically vary less than 5% KE from the minimum 5 g/p/p all the way to about 10 g/p/p. having that much diffence with only 1 g/p/p is not normal or usually accepted.

ke= M x V squared / 450,240

350 gr at 270 = 56.67 ft/lbs
400 gr at 260 = 60.06 ft/lbs

It is closer to 3 lbs.
 

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...and interestingly enough (or not) 3 lbs down from 60 happens to be 5% less. Looks like you're both right.
 

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I just turned my bow down in poundage and now have a choice of two spines. The difference in the two is around 50 grains on finished arrow weight. I can shoot the heavy arrow at 260fps with about 60 ft/lbs of energy or the lighter arrow at 272 fps with a shade over 56 ft/lbs. of energy. Which route should I go or does it really matter? I should also add that arrow flight is good with either.:confused2:
ke= M x V squared / 450,240

350 gr at 270 = 56.67 ft/lbs
400 gr at 260 = 60.06 ft/lbs

It is closer to 3 lbs.

Actually, it's a 2.55 ft/lbs difference or 4%.

350 gr at 272 = 57.51 ft/lbs
400 gr at 260 = 60.06 ft/lbs


Either could do the job but I would choose the heavier arrow.

:cocktail:
 

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KE all the way!!!
 

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Heavier arrows normally group better for me...I would say the heavier as well.

Now if there was a 30 fps difference...would probably say lighter.

Theres no real difference in POI for most practical shots on a 12 FPS difference.
 

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ke= M x V squared / 450,240

350 gr at 270 = 56.67 ft/lbs
400 gr at 260 = 60.06 ft/lbs

It is closer to 3 lbs.

Yah......I know the formulas...thanks for reminding me though....

What I was referring to was your speed. Usually 12 f/s in bow speed and 50 grains in arrow will be less than .2 ft/lbs difference...

where did you get your data? typicaly 50 grains in arrow weight is more like 18 f/s not 10....so the KE would be much closer.....

Thats all I am saying.....I know the formulas, but your 12 f/s and 50 grains doesnt jive.....
 

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Once again if the range is <30 yds you don't need the extra speed...your not shooting far enough to see a differance.
 

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Discussion Starter · #17 ·
I am confused

Yah......I know the formulas...thanks for reminding me though....

What I was referring to was your speed. Usually 12 f/s in bow speed and 50 grains in arrow will be less than .2 ft/lbs difference...

where did you get your data? typicaly 50 grains in arrow weight is more like 18 f/s not 10....so the KE would be much closer.....

Thats all I am saying.....I know the formulas, but your 12 f/s and 50 grains doesnt jive.....
I can't get a handle on what you are arguing. 12 fps and 50 grains will result in more than a .2 ft/lbs difference. I showed that with the KE formula. That is what it is, the math doesn't lie. As far as the 50 grains being an 18 fps difference, that is all speculation. That may be a rule of thumb but every bow is different. A more efficient bow will not have the drop off that a less efficient bow may have so being 6 fps faster than the rule of thumb is not out of the question. As far as my data, I have my own arrow scales and chrono. My scales are calibrated and my chrono is within 2 fps of the local pro shop so I feel confident that my data is correct. I shot every arrow that I have of both spines and the largest margin of difference was 13 fps
 

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I can't get a handle on what you are arguing. 12 fps and 50 grains will result in more than a .2 ft/lbs difference. I showed that with the KE formula. That is what it is, the math doesn't lie. As far as the 50 grains being an 18 fps difference, that is all speculation. That may be a rule of thumb but every bow is different. A more efficient bow will not have the drop off that a less efficient bow may have so being 6 fps faster than the rule of thumb is not out of the question. As far as my data, I have my own arrow scales and chrono. My scales are calibrated and my chrono is within 2 fps of the local pro shop so I feel confident that my data is correct. I shot every arrow that I have of both spines and the largest margin of difference was 13 fps

Look I wasnt looking to start an argument, sorry of you took it that way. You even made me get out the Chrono and scale myself and do some testing and YEP sure enough....

Bow BowTech Captain 70# 29.375 draw
Arrow #1 2312 total weight 358 grains
Arrow #1 CXL250 total weight 319 grains
Arrow #3 2512 total weight 541 grains

Arrow #1 Speed 300 f/s with 71.1 ft/lbs KE
Arrow #2 Speed 317 f/s with 70.8 ft/lbs KE
Arrow #3 Speed 245 f/s with 72.0 ft/lbs KE

This is what I was trying to explain. What you are seeing with only 50 grains isn't normal!? What kind of Bow is that? Maybe your bow IS different and it defys logic....I have learned never to rule anything out.

I tried my Bowtech Allegiance with the same arrows

Arrow #1 283 f/s 63.8 ft/lbs
Arrow #2 299 f/s 63.5 ft/lbs
Arrow #3 232 f/s 64.6 ft/lbs


As you can see from these tests my TWO bows vary about 1 ft/lbs with an arrow weight variance of 220 grains and speed variance of over 60 f/s.....

I just find it weird that you are getting 4 ft/lbs with just 50 grains of variance....thats all I am saying.

So to answer the original question.....go with the arrow that spines better and groups with broadheads the best!
 

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What are you hunting? I shoot 54# of ke. and blow through every whitetail I shoot unless I hit the oppisite shoulder. If your going after something bigger the more KE the better.:darkbeer:
 
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