245 fps Arrow Drops 2+ ft from 40 to 45 yds?

[Mighty Mouse]

I respect Aron and appreciate all the great info he shares, but I think he was way off on his numbers when he said a 245 fps arrow will drop 5-8" per yard from 40 to 45 yds on the recent Kifarucast with Bill Pellegrino (skip to 1:25:40 for the relevant segment).

I did some quick testing today with 240 spine arrows weighted up to 625 gr shot out of a Hoyt Helix at 70#/28.5". Chrono was consistently reading 244-245 fps at launch. I got my single pin slider dialed in at 40 yds, shot two arrows at 40 yds, moved back to 45 yds, and shot two more arrows using the same point of aim without adjusting the pin. I shot several 4 arrow groups using this method and the average vertical difference in POI from 40 to 45 yds was around 5", which is not insignificant but is nowhere near the 25" plus Aron was claiming. I'm not trying to evangelize for super heavy arrows (I fully appreciate the benefits of speed/flat trajectory, especially in western hunting), I'm just curious if I was the only one skeptical of the dramatic drop numbers Aron was quoting.

Forgive the horizontal dispersion, there was a gusty crosswind blowing and I wasn't making any effort to compensate, just focusing on cutting a horizontal line through the bullseye with my pin.

 

[Billy Goat]

Did you try with flu flus?

 

[5MilesBack]

I haven't heard it, but I would agree that 2 feet would be WAY too much drop for only 5 yards.......or even between 40 and 50. Everyone should shoot their setups at every distance they have pins for with the other pins around it to see what really happens. Or just hold your bow up and look at your other pins to see where those arrows would hit on the target.

 

[540-Virginian]

No engineer, but im thinking vane configuration will greatly play into the results due to the drag variances?

 

[Mighty Mouse]

No engineer, but im thinking vane configuration will greatly play into the results due to the drag variances?

Vane choice definitely has the potential to affect trajectory, but I don't think any reasonable fletching configuration will produce the drop Aron was claiming. FWIW the arrows I was shooting had 4 low profile 3" vanes at 3° offset.

 

[N2TRKYS]

How much poi shift do you see at 20 yards, while using your 40 yard pin?

 

[Marble]

Looking at the ballistics calculators it should be around 28-30" drop from 40 to 50.

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[CoStick]

Looking at the ballistics calculators it should be around 28-30" drop from 40 to 50.

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ballistic calculations

 

[Page Master]

Possible he just misspoke numbers, but somewhere between 35-50 most arrows are hitting and passing the apex of their flight and that is when you'll see the big gaps.

 

[5MilesBack]

Possible he just misspoke numbers, but somewhere between 35-50 most arrows are hitting and passing the apex of their flight and that is when you'll see the big gaps.

The gaps should be fairly linear and grow with every additional pin in your sight. Here's one of my 7-pin sights set for 20-80, and as you can see, the gaps get larger with each pin.

 

[Page Master]

The gaps should be fairly linear and grow with every additional pin in your sight. Here's one of my 7-pin sights set for 20-80, and as you can see, the gaps get larger with each pin.
View attachment 323398

Yes, but the biggest gap on my slider is between 30-40, everything else stays pretty consistent. I keep my 3pin 20-35-50 so I have something right in the biggest arc of my arrow.

 

[Zac]

If you all were shooting adult arrows they would only lose 2 fps, and .0 something ke at 60 yards. Your pin gaps would be almost exact from pin to pin.

 

[Billy Goat]

The high point of the parabola depends on how far you are shooting.

Drop is also linear. If you are seeing a difference that stands out it's because you're slipping your anchor.

 

[H80Hunter]

Yeah I’m guessing he mis spoke because that’s way off. It’s easy enough to test on your own.

 

[Hoot]

Well….he did start drinking again recently….

 

[Mighty Mouse]

How much poi shift do you see at 20 yards, while using your 40 yard pin?

That's a little beside my original point/question, but I indulged your curiosity (and mine) anyway...I'm hitting about 8" high using my 40 yd pin at 20 yds with this setup.

 

[N2TRKYS]

That's a little beside my original point/question, but I indulged your curiosity (and mine) anyway...I'm hitting about 8" high using my 40 yd pin at 20 yds with this setup.
View attachment 323419

Thank you for doing that. I like setting my single pin up for these kind of shots. That’s where a balance of weight and speed is a factor for me.

As for your original post, that seemed way off to me as well. I don’t listen to podcasts, but something didn’t sound right about that.

 

[87TT]

I know when I shot 20 yard target with my 20 yard pin but my MBG sight was still cranked up to 100, my arrow left town over the target and hay bale (3) backstop.

 

[Mighty Mouse]

Looking at the ballistics calculators it should be around 28-30" drop from 40 to 50.

What calculator are you looking at? The free ones I found with a quick Google search showed similar drop numbers but were assuming a 0° (perfectly horizontal) launch angle, which will vastly overstate drop at distance because it ignores the fact that an arrow is launched at an angle above line of sight which causes the arrow to rise then fall (relative to line of sight) on its way to the target.

Out of curiosity, I dusted off my copy of an obscure book called Archery Calculations and used its trajectory simulation method to model the flight path of my test arrow. Aiming with a pin sighted in for 40 yds (1.9° launch angle), this method predicts my arrow will be 7" low at 45 yds and 15" low at 50 yds, which is reasonably close to what I saw with my test shots (5" low at 45 yds).

 

[Marble]

Arrow Ballistics Calculator - Kinetic Energy, Drop, Momentum

Up to 70 yards out of arrow ballistics information - simply provide arrow weight and speed and our calculator does the rest.

www.bestcrossbowsource.com

I wonder how significant the launch angle affects the down range do. I'm thinking significant but that just a guess.

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