Altitude & Arrow Speed

[straight_arrow]

We all know that altitude has an impact on both speed and distance an object travel. I'm interested in understanding the performance of the same arrow shot at sea level vs. 7,500 feet and is there a calculation that will provide the answer. Please redirect if this topic has been previously discussed.  Thanks, Mark

[old_goat2]

Mark, while there is a difference, has to be,I can't tell it, even with my compound shooting in Kansas at 2500 ft or Colorado at 10,000 ft my pins were on target, don't notice a difference with trad gear either. I've seen this question on a lot of forums and I've seen people say they noticed a difference, I haven't and vast majority don't either, maybe it's because I'm sighted in, in the middle of the altitude range.

[khardrunner]

The speed difference would be undetectable even with the best in chronography. An arrow is to be considered a ballistically efficient projectile so air resistance is negligible. That mean, even at sea level, the horizontal velocity does not change so the velocity when the arrow leaves the bow is the exact same (horizontally speaking) as when the arrow hits the target.

This concept will remain unchanged at altitude since air resistance is negligible at sea level.

[Cyclic-Rivers]

I shoot worse at high altitudes.  Oxygen is sparse at 80,000 feet and I have a hard time holding when I cant breathe.

At 7,500 feet I didn't notice any difference though, or at 11,000 feet for that matter.

[McDave]

While air resistance may be negligible for a bare shaft, we know that longer fletches or more fletches definitely affect arrow velocity down range. So I wonder if the reduced air pressure at higher elevations has a noticeable effect on fletched arrows.

[chanumpa]

Never will forget when I came straight out of the Dakotas,and climbed your Mt.Crested Butte and got altitude sickness.Not good!I do know it is exteme,the amount of distance that you get out of a golf ball hit at a sea level golf course v.s. a mountain course say at 4,000 ft.How does this translate to arrows?Id say,when you are way up there in those 14 teeners,you better stay close,I was dizzier than 60 miles off shore for 3 days!

[khardrunner]

McDave, it's also true with feathered shafts. Yes, there is some air resistance by it is VERY small compared to the velocity of an arrow. On the order of less than 1-2% is my guess. As long as the arrow is tuned well, a spinning shaft will create very little drag whether it's feathered or not.

[khardrunner]

Take a chrono out in your yard (if you dare) and shoot through it a varying distances... you'll see what I mean. There is little to no horizontal acceleration (or slowing down in this case).

[Orion]

It might be in my head, but when I get into the mountains from relatively low country, I seem to shoot high for a little bit.  Doesn't take but a few arrows to adjust, but it always seems to happen to me the first day in camp in high country.

[S.C. Hunter]

I tend to shoot slightly higher. I was at a shoot up near Big Bear at Jenks lake and it took me several shots to get on target. I was only about 3-4 inches high at 20 yards but on a few shots around 40-60 yards I was a foot over the back of the 3-D animal. I corrected it before the shoot was over but it was messing with my head. We were at around 7,000 ft.

[McDave]

We purposely use flu-flus to slow the arrow down when shooting at a flying target, so we can find the arrow after we shoot it.  I believe Olympic archers use minimal fletches for the opposite reason, to minimize arrow drop at the relatively long distances they shoot.  So I would assume that if these configurations have the desired effect at the extremes, then changing from a 4" feather to a 5" feather would have some effect at the ranges we normally shoot?

[khardrunner]

But the difference in surface area of feathers is astronomical compared to air density differences.

[FerretWYO]

I have shot from Florida to over 12000 feet. Don't sweat it.

[**DONOTDELETE**]

And here i thought the post read "Arrow speed and Attitude"          

i don't know about arrow speed at high altitude, but a 6 pack of beer at 14,000 will definitely leave a mark....      

[straight_arrow]

Thanks to all for your perspective.  Have a great holiday.

[Retnuh Wob]

This subject interested me so I did the drop calculations. Aerodymnamic drag is proportional to the air density. I assumed an arrow leaving the bow @ 200 fps loosing 3 fps for every 5 yds of travel at sea level. At 10,000 ft air density is approximately 2/3rds of sea level so I calced the same arrow loosing 2 fps for every 5 yds @ that elevation. At 35 yds I got 57" of drop for both scenarios. So no difference out to that range.

A flu flu arrow might be a bit different as it could be that the higher fletching may lay against the shaft for a while after the arrow leaves the bow. This would change the profile increasing the drage latter in the arrow flight as it slowed down. However, I don't know if that would have a significant affect as flu flu arrows are usually used at shorter range anyway.

So if you send your arrow over the back of that trophy buck up in the mountains, you will have to find another excuse besides air density  

[The Hawk]

With half of the atmosphere laying below 18,000' and drag increasing exponentionaly with speed, the arrows trajectory will be flatter at higher density altitudes (less drag). It will be more apparent to the shooter in lighter, faster arrows where the drag is a greater percentage of the arrow energy. I blame this for my high altitude misses! Proof: My data shows that I have never missed an elk below 8,000' and I have never missed anything below sea level!!!!          
Aerodynamics show the arrow will be a little higher at higher altitudes on longer shots, I'm not good enough to notice!

[Roughrider]

I've never noticed a difference.  If there were a difference, I would think it would be so minimal at archery distances, that you wouldn't be able to notice - just a guess, maybe .1 inch @ 40 yards.  It takes a pretty big change in arrow speed to notice much impact difference at archery ranges.  I would guess few archers would detect a 5 - 10fps speed differential shot to shot at ranges under 30 yards.

I usually tend to underestimate distances at higher elevations, hence, shoot lower,I think it is a combination of the clear air and vast expanses.  I also notice that in low light I tend to overestimate distance and shoot high.