** BROADHEADS ** Science & Math

It would be interesting to see if a fixed blade broadhead would fly with less speed loss. With no vents in the blades there would be less turbulence, probably less drag and maybe a wing effect. Don't know for sure but it would be interesting to see.

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I think most people have mentioned, every broadhead will have a little different drag factor. But even the Sevr was 3+% behind and that mechanical has nearly nothing external on it.
 
sneaky said:
No one has even mentioned elevation in this equation. Drag at 10k feet is different than drag at sea level.

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Click to expand...

Sneaky, I don’t think elevation is as significant. Long ago Randy Ulmer did an article on it and it was very minimal, something like him taking a half turn out of his limb bolts at 10k feet. That is only 3-5 FPS depending on the limbs.

For me I would just rather not mess with my bow, I will just cut a yard off what my range finder says when hunting at those elevations.

If I hunt Nevada this year I will take a target with me and shoot some at 10k for personal knowledge.
 
It would be interesting to test this with heavier arrow weights to see how increased momentum is affected by a fixed amount of drag.
 
S.Clancy said:
It would be interesting to test this with heavier arrow weights to see how increased momentum is affected by a fixed amount of drag.
Click to expand...

I think There is a post that shows some heavier weight arrows at 65 slowed down at damn near the same percentage as the lighter ones.

I would surmise they would be the same at 100 also. It would be how much the physically drop compared to a FP.
 
Billy Goat said:
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.
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This!!! Exactly right. Awesome thread.

100% Bh and field point grouping are dependent upon arrow weight.

Let’s go extreme, an arrow will only decrease 4fps from 0-70 yards if you shoot a 1000gr arrow at 78lb. Yeah it’s only shooting 212fps but only down to 208. The heavier the arrow the closer impact you will have of the two because the control is given to the weight of the shaft and momentum, wind resistance is less of a factor. I’m shooting a 606gr arrow and bh and field points group amazing out to 70yrds.


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Rosinbag, that is an awesome test and exactly what I would expect given the substancial difference in drag between a fixed blade and a FP. This is common sense really but it is great to see a really good test done to confirm. With a vented fixed blade you can hear the whistling, this is a dead giveaway that you are losing energy somewhere, in this case it's in the form of extra drag. For what it's worth, I shot the Daysix 1.25" broadheads at 70 yards and they consistently hit 0.5" ABOVE my FP! What?!?! I believe in newtons laws of motion more than my imperfect form. I think with broadheads I must subconsciously focus harder and maintain a stiffer bow arm or float the pin slightly above the bullseye just before release.
 
What people are forgetting is that broadheads are planar. If your broadheads have the same point of impact vertically as field points at distance, it probably means the broadheads give the arrow some lift, which coyls cancel out the drag. It could also be that the broadheads have more weight at the back of them, making the arrows more tail heavy. Those are the only scientific theories I have. Bill
 
33.6
27.5
26.1

The fps lost between the 3 arrow weights tested above.

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FWIW, none of those 3 arrow weights tested above are exactly heavy either. 482gr was the heaviest.

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S.Clancy said:
It would be interesting to test this with heavier arrow weights to see how increased momentum is affected by a fixed amount of drag.
Click to expand...
Drag cannot be fixed, since it's related to velocity, which changes. Do you mean using heavier arrows with the same broadhead. Would the heavier arrows have the same outside diameter? Intuitively, the heavier the arrow the less affected by drag it should be. Think of a big dually with a car topper on it versus the same car topper on a real small car. Sounds like you'd like quantified tests?
 
sneaky said:
No one has even mentioned elevation in this equation. Drag at 10k feet is different than drag at sea level.

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Click to expand...
That's right. I'd guess if your broadheads hit where your field tips do at one elevation, they probably will at the other extreme.
 
Billinsd said:
That's right. I'd guess if your broadheads hit where your field tips do at one elevation, they probably will at the other extreme.
Click to expand...
Not exactly. Two different surface areas you are comparing. Field points and BH have different aspects, and surface areas.

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Good test.

Dudley said the the same thing your test found on a recent podcast.

Fixed heads have more drag than FP, no way around it. At longer distances this becomes very evident.


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