# Arrow flight in heavy air



## lees (Feb 10, 2017)

Water vapor is less dense than air, not more. So higher relative humidities should give effects, if there are any, of higher altitudes/thinner air. I suspect perhaps a placebo effect maybe, especially if you think you're seeing the opposite? Otherwise, I've not noticed any altitude effects of any significance. I can go shoot down in Albuquerque, a little over a mile in altitude and set my sights. Then go into the mountains with my portable Bowtree and practice at 9000' MSL and I don't have to move my sight to shoot at the same 20 yards. Even with my Tribute which lobs arrows at about 170fps or thereabouts.

Maybe there could be an effect at longer distances, or at much more drastic changes in density altitude however. It would make sense, but probably only with very wide variations. 

lee.


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## SonnyThomas (Sep 10, 2006)

Air density does effect arrow flight, but most won't notice. Still, heavy air, high humidity and rain has a double effect. The strings can absorb moisture, become heavy. This is not notice so much with a compound bow because of the strings having pressure, but both together it's possible to see flight effect. Traditional shooters will see this as the string doesn't have the pressure of compound strings. 2011, Illinois ASA 3D State Championship. As a late entry I was grouped with 2 Traditional shooters. We were hammered with rain, the event even stopped by Officials before the start and as those came in at the halfway point. Both Traditional shooters were baffled with their arrows falling short. C.M. noted this to me on the next target. I then told both to "twang" their strings before shooting. They weren't believing until they did "twang" their strings. Vapor flew everywhere. A 2nd "twang" result in a bit more. When they shot their arrows hit solidly. From there on the two Traditional shooters "twanged" their strings before each shot until the rain stopped.


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## eclark53520 (Sep 11, 2012)

Humid air is less dense than non-humid air. 

You're arrows are not seeming 'sluggish' because of humidity. Physics say so pretty clearly.


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## whiz-Oz (Jul 19, 2007)

The difference in mass between 100 percent humidity and 0 percent humidity air is that the 100 percent humidity air weighs 95.454545 percent of the 0 percent humidity.

To the arrow, it make bugger all difference. I see people regularly bringing up humidity related air questions on archery forums around the world. 

Here is the fun part: 
Everyone assumes that the humid air is denser and to blame for what they see in terms of slowing things down. The difference between the range of densities that humidity can make is not much. 

Nobody bothers about the temperature which can change air densities a bit more than humidity can. 

So why do people make observations that suit their assumptions about humidity which are actually wrong, yet never notice changes caused by temperature? 

Maybe because they have no preconceived idea to confirm?


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## Larry Nelson (Aug 22, 2017)

I know that cool air is denser than warm. In cars cool air helps make more hp than warm. For a golfer altitude and thin air gives longer ball flight. These things may not have a drastic effect on arrow flight, but there is some though.


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## grantmac (May 31, 2007)

Golf balls use the magnus effect so air density is far more noticeable than on a purely ballistic low-speed projectile.


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## lees (Feb 10, 2017)

Larry Nelson said:


> I know that cool air is denser than warm. In cars cool air helps make more hp than warm. For a golfer altitude and thin air gives longer ball flight. These things may not have a drastic effect on arrow flight, but there is some though.


The main effects of altitude tend to be on surfaces that generate lift, rather than simply incur parasitic drag. That's generally the case with arrows, where lift is generally only used by the vanes/feathers to correct the flight of the shaft. If the flight is really bad, there will be some induced drag there, but mostly you're looking at a very low drag situation with most arrows.

That's mostly just a roundabout way of saying the effects of small altitude changes (say a couple thousand feet) are going to be negligible, especially with todays heavy arrows shot fast out of a good speed bow. 

However, if time and money were in infinite supply, I would probably conduct an experiment on the extremes. Say, go sight my bow in down at sea level somewhere on the continent, and then go up to the ski area behind where I live at a little over 10,000' MSL and see where my sights are up there. I wouldn't be surprised if there wasn't an effect at longer distances with say my GT 400's which aren't that skinny....

lee.


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## Rick! (Aug 10, 2008)

If you're concerned about arrow flight at altitude and are going out west, take a target with and shoot a few shots before heading up the hill. 
I have shot my target rig below 1000' and above 5000' feet in the same year. I think I took out a few clicks to bring POI back to 'zero'. 
One also has plenty of time to acclimate for shoots like the Utah Open or other tournaments to make adjustments if necessary. 
I don't ponder 'what ifs' when I go to altitude.


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## Jcborgeson (Dec 18, 2016)

Interesting topic on that I have been curious about for some time. On my recurves, including my Hoyt Formula Factor Olympic rig, the sight movement required to get on target on a very humid 90 degree day vs a low humidity 60 degree day is profound; about 6mm higher on my Shibuya sight on the 90 degree day for a 20 yard distance. I suspect there is more in play here than just humidity. Perhaps the higher temps affect the rebound of the limbs, string and riser itself. Might even effect the drag on the string from the finger tab. I use a clicker and have gotten good at holding the tip of the arrow right on the end of the clicker until just before release so I do not think I am short drawing or collapsing on release. 6mm change is always surprising to me as none of my compounds seem to have any POI change based on humidity or temp even out to 70 yards.


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## knarrly (Dec 21, 2004)

Rick! said:


> If you're concerned about arrow flight at altitude and are going out west, take a target with and shoot a few shots before heading up the hill.


The above is the only sure way to gauge if your arrows are doing anything different. I went to a field shoot where it was 2500 ft lower in elevation and didn't think it would be enough to matter (just took warm up shots at 20 yds because i KNEW my pins were good), the first day wasn't any fun having to guess where to hold my pin (bhfs) at different distances. Needless to say i hit the practice range and reset my pins before the second round.


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## SonnyThomas (Sep 10, 2006)

Humid air and cool........ Last Fun Day of the year and I hit the practice range early before I left. My shots were just a tad low...Went to pull my arrows they were near dripping wet. Shot the Fun Day and was dead on. Got home just few minutes ago, shot a few rounds and dead on.


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