Wind Drift - Just the facts

[Merlin Archery]

A challenge for those more intelligent than me. (ok, insert own joke here… )

Is there a mathematical equation someone can explain to me that would calculate wind drift on arrows? Or one that has been done and you can point me to it?

Specifically, I’m trying to work out the distance an arrow will drift at 70m in a cross wind. I know current thinking says a heavy, thin arrow is supposed to be the best. But how much exactly? If heavy and thin is better than light and thin, why not a really heavy fat one? Or a super fast thin one?

Reason is I don’t like relying on what other people tell me without understanding the facts. Second reason is my light, fat arrows group really, really well!

Is there a formula, computer program, anything that I could substitute the following values and get the answer ‘Drift Distance’ –

1/ arrow weight
2/ arrow speed
3/ arrow diameter
4/ wind speed

Come on. Sharpen those pencils and show me how its done.

[Old Bloke]

Hi Ben!

Believe it or not there is a calculation for working out wind drift! When I'm flying I use a hand held mechanical *computer* for working out degree's of drift so that a heading can be set which causes the aircraft to *crab* (fly sideways) but flies in a straight line between two points. My * computer does it for me. . I'm sure sailors use the same *rule* when tacking. I'll have a shuftie around aviation navigation sites to see if there is a common (rule of thumb) calculation..there must be...otherwise my *computer* wouldn't work.

Alternatively, you could type into Google..*Wind drift calculation* and if you have about 10 hours spare!!!!..............

[buzz lite beer]

I can't give you a formula off the top of my head but there are some similar ballistic programmes available using them and what I have picked up from my rifle shooting buddies, is that wind drift is amplified as energy retention is lost, so fundamentally a fast light projectile will drift the same amount as a relative slow heavy one. The .177 cal. vs .22 cal. air rifle pellet has been discussed to the same effect neither has been accredited superior in terms of wind drift, the lighter .177 just has a much less pronounced trajectory. If you can get a heavy fast projectile that retains energy down range you will suffer less wind-age.

[moo-mop]

ummm.... you really must validate any models/equations before drawing conclusions from them. I think you'd actually have to get out there with some properly planned experiments (I work on model validation). I'm sure this has been done for the aircraft, but I'm pretty sure it won't have been done for arrows!
I saw a program about drag of arrows being calculated from facts know about bullets, it was quite wrong, and shown to be so from a rather simple test.

[Bald Eagle]

So I guess max allowed compound poundage over 2315 Cobalts equals ten!!

[King Custard]

This is a real ''thinking mans'' question!
Way beyond me..

But then most usually Ive found the wind 'gusts', and to have a real practical value in shooting, wouldn't you have to know the precise strength, speed direction of the wind - as you release and at several points up to the boss?
Now that sounds to me like one or more calculations I don't want to make when there's so much else going on...I'm sure I'd get on better if I feel the wind, see the flag, watch the grass, hear the tree, 'smell' the air getting denser etc

YET
For checking (in Theory) one arrows performance against another using a wind machine indoors your results may well Upturn all current thinking on which outdoor arrow pattern will win the next World Champs!- I for one would Love to be privvy to that info conducted by someone who doesn't Make the arrows. Very interesting!
A big thumbs up, all power to you! We could soon see arows marked with spine rating and winddrift rate!

[LineCutter]

Nobody's mentioned Joe Tapley's Wind Drift program yet! You can find it on his website.

[clickerati]

I'm too pea brained to add anything to this thread except...welcome back, Ben. Nice to see you posting!

[Random_guy]

Hmmm intrigueing. I'm about to buy new arrows and was playing with Joe Tapley's drift program (am trying to decide between nav's and ACE's...). Even after altering the ACE diameter to fit the updated measurements on the website, the program showed negligible difference between the ACE's and Nav's for the spines i'd want (compared ACE 670's to Nav 710's, as there are no Nav 660's on there...).

Very strange indeed. Perhaps at the smaller diameter end of the scale, the benefit of the barrelling on the ACE's and the lighter shaft is lost? (both came up similiar in weight). Just a thought....

[Marcus26]

Accurate Sights has it built in, plus a very very neat Matchplay simulator.