** BROADHEADS ** Science & Math

[Billy Goat]

Here are a few more data points. Not with broadheads. But different arrow weights at distance. Bow was a Hoyt carbon defiant 34. 29" draw set on 72#. Arrows were carbon express Maxima hunters. Had 3" fusion vanes. Played with tip weight to see how it changed velocities. Had 100 grain with standard insert (350 shaft), 100 grain with 50 grain insert(450 shaft), and 125 with 50 grain insert(450 shaft). Shafts were cut down a bit on the heavier tip weight arrows.

Arrow weight: 391.5 grains. 3' velocity - 313.7 fps, 65 yard velocity - 280.1 fps


463.4 grains, 3' velocity - 290.5 fps, 65 yard velocity - 263 fps.


482 grain arrow, 3' velocity - 285.4 fps, 65 yard velocity - 259.3 fps.

So you can see how the mass of the heavier arrows help them to overcome the external forces. This wasn't a test of broadhead flight but rather about retained energy. Actually used 9 different arrows. 3 of each weight. Averaged all the data for each setup. Average weight of the 3, average speed of the 3.

 

[RosinBag]

Good stuff Doug.
There has got to be a math guy on here to figure out what actual POI would be given those speeds??

They allow archers to fling BH at Maya?

The mathematician would say it depends on arrow weight and initial speed. 20 FPS at 100 yards out of my bow will drop a different amount compared to 20 FPS out of a slower/faster bow or heavier/lighter arrow.

And you bet on BH’s at Maya. 105 yard practice bale and a BH pit with 3D animals set up in it. We also shoot a BH league Saturday mornings. All 3D targets.

 

[RosinBag]

Here are a few more data points. Not with broadheads. But different arrow weights at distance. Bow was a Hoyt carbon defiant 34. 29" draw set on 72#. Arrows were carbon express Maxima hunters. Had 3" fusion vanes. Played with tip weight to see how it changed velocities. Had 100 grain with standard insert (350 shaft), 100 grain with 50 grain insert(450 shaft), and 125 with 50 grain insert(450 shaft). Shafts were cut down a bit on the heavier tip weight arrows.

Arrow weight: 391.5 grains. 3' velocity - 313.7 fps, 65 yard velocity - 280.1 fps


463.4 grains, 3' velocity - 290.5 fps, 65 yard velocity - 263 fps.


482 grain arrow, 3' velocity - 285.4 fps, 65 yard velocity - 259.3 fps.

So you can see how the mass of the heavier arrows help them to overcome the external forces. This wasn't a test of broadhead flight but rather about retained energy. Actually used 9 different arrows. 3 of each weight. Averaged all the data for each setup. Average weight of the 3, average speed of the 3.

That is very interesting. I should do more number stuff as it is eye opening.

Your three test arrows lost 89.17%, 91.2% and 90.7% respectively. My test arrow lost 91%. All four very close numerically. I would bet the difference in actual drop would be good to know for each.

I could probably shoot 60 yards using my 20 yard pin and figure out actual drop for lighter verse heavier arrows. Archers advantage has a setting that you can get that number but it isn’t very accurate compared to shooting them. I could probably do it at 100 if I stuck an aiming for high up on the back stop.

I think there is an optimum weight to speed out there that gives you the best of both worlds.

 

[307]

What an exceptional test. It confirms and puts actual numbers on what is pretty obvious from a physics perspective, broadhead drag significantly affects POI.

Thanks to Doug for doing this.

The Flat Earth Society of archery, aka, the "fixed blade flies the same as field points to 100 yards" club is likely to implode with such information, but I guess that's just a risk we have to take.

 

[MT257]

Well
After seeing this I guess after next weeks TAC event I will begin to build my broadhead tape. I’ve always been under the assumption that they flew the same. But I read and understand that they don’t. You said you test stabilizers a lot. Do you find a longer ata bow requires a shorter/longer or lighter/heavier stabilizer to reduce pin float?

 

[justin davis]

What an exceptional test. It confirms and puts actual numbers on what is pretty obvious from a physics perspective, broadhead drag significantly affects POI.

Thanks to Doug for doing this.

The Flat Earth Society of archery, aka, the "fixed blade flies the same as field points to 100 yards" club is likely to implode with such information, but I guess that's just a risk we have to take.

So how does one explain it when I tune my bow to shoot broadheads and field points and they group the same out to 100 yards??
I’ve done it in the past and I’ll continue to do it.

I think broadheads make a difference and also people ability to tune.

I also think there is a conversation to be had in regards to whether or not having your broadheads hit the same is the best tune or not? But to say Bh and field points can’t hit the same spot I don’t agree with.


Here are two pics I had on my phone. One is at 60 yards a BH and field point.

The other is a group I shot right before a hunt at 80 yards.

2 field points and a BH Looks pretty close to me

 

[RosinBag]

It’s all relative. I think holding weight plays as much a part on pin float as correct precise draw length and stabilization.

Long bar means you can use less weight than on a shorter bar. That’s a very simple way to put it. A 30” with 7 ounces could have the same effect as a 27” bar with 9 ounces.

The best way for me to get pin float dialed with a new bow is shoot it with no bars at all. Adjust your draw length in small amounts until you find you have the least amount of pin float, then screw some bars on and play with weights to make it better. But certain bows require different weighting depending on where you mount your bars, angle of them, etc. Even the type of shot you shoot will effect your weights.

 

[JNDEER]

Well. Out of the bow seemed as if the speeds for FP and BH (fixed) were the same. So that number, although would be needed in the calculation, doesn't really matter. Nor does the weight of the arrow because 20 FPS slower is 20 FPS slower (just running with your set up, not trying to compare it to mine because my difference may be more along the lines of 25 or 30 FPS) Just in general wondering if we look at your data how many inches low will 20 FPS give you at 100 yards.. we got to have a math geek on here somewhere.

That is good to know. Next time I am up that way I will have to drop in to shoot some.

 

[RosinBag]

So how does one explain it when I tune my bow to shoot broadheads and field points and they group the same out to 100 yards??
I’ve done it in the past and I’ll continue to do it.

I think broadheads make a difference and also people ability to tune.

I also think there is a conversation to be had in regards to whether or not having your broadheads hit the same is the best tune or not? But to say Bh and field points can’t hit the same spot I don’t agree with.


Here are two pics I had on my phone. One is at 60 yards a BH and field point.

The other is a group I shot right before a hunt at 80 yards.

2 field points and a BH Looks pretty close to me

I don’t think you can tune speed out. Your bow could be set up to shoot the longer yardages closer than your short ones.

Are those your average groups at 60 and 100? If not what are they? If you shoot 20 broadheads and 20 FP’s what is your group size? 8”? 10”? 15”?

 

[RosinBag]

Well. Out of the bow seemed as if the speeds for FP and BH (fixed) were the same. So that number, although would be needed in the calculation, doesn't really matter. Nor does the weight of the arrow because 20 FPS slower is 20 FPS slower (just running with your set up, not trying to compare it to mine because my difference may be more along the lines of 25 or 30 FPS) Just in general wondering if we look at your data how many inches low will 20 FPS give you at 100 yards.. we got to have a math geek on here somewhere.

That is good to know. Next time I am up that way I will have to drop in to shoot some.

For my hunting bow 20 FPS at 100 yards would be roughly 5-6 yards so about 15” or so of impact difference. I usually see between 2”-4” of drop per 3 FPS at 100 yards depending on what bow I am shooting and what type of point.

 

[justin davis]

I don’t think you can tune speed out. Your bow could be set up to shoot the longer yardages closer than your short ones.

Are those your average groups at 60 and 100? If not what are they? If you shoot 20 broadheads and 20 FP’s what is your group size? 8”? 10”? 15”?

Yea maybe my tunes are for longer game. I enjoy shooting long range practice but I don’t hunt at those yardages.

I’ll have to do some shooting and measuring. I have found a lot of broadheads to drop off pretty quick once you get out past 60. But Ive found a few brands and designs that shoot better out further

 

[JNDEER]

Justin- I know a guy (member here) who tested it taking out the human equation using the hooter shooter. BH will hit close, but not on top of the field point.

You may be able to stack them in a shot, but that doesn't mean you didn't release with the pin a touch high or low either way, giving you those results. But, I will say that is some good shooting!

 

[307]

So how does one explain it when I tune my bow to shoot broadheads and field points and they group the same out to 100 yards??
I’ve done it in the past and I’ll continue to do it.

I think broadheads make a difference and also people ability to tune.

I also think there is a conversation to be had in regards to whether or not having your broadheads hit the same is the best tune or not? But to say Bh and field points can’t hit the same spot I don’t agree with.


Here are two pics I had on my phone. One is at 60 yards a BH and field point.

The other is a group I shot right before a hunt at 80 yards.

2 field points and a BH Looks pretty close to me

Lots of potential answers to that question, but physics is physics, drag is drag, and gravity never sleeps. What you are stating is mathematically impossible if we agree that a fixed blade broadhead will have more drag than a field point, and I think we all agree on that, right?

Perhaps you subconsciously aim higher with broadhead? Perhaps your tune is a bit knock low and that gives the arrow a slight bit of lift that offsets the effects of drag...?

 

[justin davis]

Yea Maybe so. I’m aiming for the same spot not
Higher. I usually bareshaft tune and when my bareshafts are hitting with fletched then that usually means a fixed blades hits with fletched for
Me.

Here is a pic of a field point and an Iron will fixed blade at 105 yards. Fixed blade is on the bottom. Aiming for the green dot which I’m off a little but both arrows are pretty darn close for 105.

Next pic is the next groups I shot. Again it’s at 105 yards. 1 BH shot 1st and then 2 field points. The BH is the middle arrow. Aiming for the green dot but that’s close enough lol

Wouldn’t you agree they are hitting together ?


I obviously can’t shoot like this all the time. But what I’m trying to convey is that it’s possible to have them Broadheads Hit with Field points at 100 yards. Because it happens.

 

[robby denning]

My fixed blades shoot lower than my field points. I start to notice it beyond about 50 yards.




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[RosinBag]

My fixed blades shoot lower than my field points. I start to notice it beyond about 50 yards.




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Robby, did you edit this? I was trying to understand your question and when I went back the question was gone.

 

[DWarcher]

Good stuff Doug...thanks for taking the time.

 

[sneaky]

So with the recent thread on fixed blade broadheads and field points impacting in the same spot through all ranges, I obviously respectfully disagree with that happening. @Billy Goat and I shared some PM's as he was interested in the actual numbers of speed degradation over distance. Today I went out and shout several arrows over the chronograph at 5', 60 yards and 100 yards. I am no scientist nor am I a mathematician, but here are my numbers.

Set Up: Hoyt Carbon Defiant 34, 69.5 #'s, 29.5" with a 420 grain arrow. The arrows are fletched with three, 310 Flex Fletch vanes if you want to take that into consideration for drag compared to your set up.

The field points were Easton Parabolic, the mechanical broadheads were Sevr and the fixed blades were G5 Montecs. (I also shot Slick Tricks and Ramcat Diamondbacks at 60 and they were very close to the Montec speed, so I didn't keep shooting them.)

The speeds are three shot averages at 60 yards and 100 yards. The speed at 5' were just one shot and recorded.

5'

Field Point - 282
Mechanical - 282
Fixed Blade - 282

* This was the outcome I expected.

60 Yards

Field Point - 256 (91% of initial speed)
Mechanical - 254 (90%)
Fixed Blade - 250 (87%)

* So the Mechanical was less than 1% slower (.0079) and the Fixed Blade was 2.34% slower than the Field Point.

100 Yards

Field Point - 230 (82%)
Mechanical -222 (79%)
Fixed Blade - 206 (73%)

So the Mechanical was 3.47% and the Fixed Blade was 10.43% slower than the Field Point.


This is why my opinion of that Field Points and Fixed Blades can't have the same point of impact over all distances. I believe that depending on your personal acceptable deviation from Field Points to Fixed Blades, one could think they were all impacting the same.

Side Note: I found the Montecs were only about 5" low compared to my Field Points, so I surmised my bow was set up to shoot the longer ranges closer. So I moved up to 25 yards and the Montecs were 4" high. So I reversed it and moved the sight to have the Montecs dead on at 25 yards, this put them roughly 16" low at 100 yards.

Obviously these were just my numbers with my set up and doesn't transfer across the board to every bow, draw weight, draw length, speed, etc. But all Fixed Blades will degrade speed at distance due to their drag factor compared to a field point regardless of the other factors present.

Heavier arrows will retain energy and momentum longer, that's a variable you also have to consider when figuring energy loss at longer distances

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[robby denning]

Robby, did you edit this? I was trying to understand your question and when I went back the question was gone.

Yes, my brain finally kicked in and I realized I was wrong on my math, as usual.


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[sneaky]

Lots of potential answers to that question, but physics is physics, drag is drag, and gravity never sleeps. What you are stating is mathematically impossible if we agree that a fixed blade broadhead will have more drag than a field point, and I think we all agree on that, right?

Perhaps you subconsciously aim higher with broadhead? Perhaps your tune is a bit knock low and that gives the arrow a slight bit of lift that offsets the effects of drag...?

No one has even mentioned elevation in this equation. Drag at 10k feet is different than drag at sea level.

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