Wind Quiz

[Park ranger]

Yep, Bryan's book does indeed say for a 308 from 100 to 600 yards, the first 100 yards will affect the flight the most. Then he goes on to say depending on transsonic area will change things up a bit. And he even further goes on to speak of wind gradient and local conditions. Academia wise, my answer was wrong if we're considering a supersonic round the whole 1000 yards. Im glad i was, it will force me to read Bryan's book over again. But, with a 69 smk starting off at 2550 and the answer may be different or do the same test in jbm with a 77 at 2850.

 

[aloreman]

Glad im to dumb to figure this out and dont shoot where theres a wall.

 

[wolley]

yep. Litz is correct.
What I was failing to see is that bullet B is curving and even though it is only 3moa off target at 500yds its angle of flight is greater than 3 minutes. It will carry that angle the rest of the way to the target.
I'm still gonna make my wind calls based on the flags closest to the target and focus my scope to see mirage at 800 or so yards. That has always worked best.

 

[dskogman]

Don't have my laptop to add the curve but a constant 10mph wind the whole distance is 99" at 1000 yds compared to 67" and 38".
I added spin drift and stabilization option and it increased to 108".

 

[Egg]

Mr. Ten X......you going to give us the answer??????

 

[284driver]

When Mexico builds the wall for us, we'll go find out for sure. Proof's in the pudding.lol

 

[Mozella]

..... snip.............
In any event, it's an interesting problem, but not one that anyone is ever likely to encounter shooting in the real world. ..... snip.........

Actually, the situation, generally speaking, is indeed one competitive medium/long range shooters face in the real world. When studying problems in a scientific way, it is frequently illuminating to take some of parameters to a limit. In this case, zero wind for half the flight distance and a significant wind for the other half. True, those extremes are unrealistic, but that doesn't mean the results should be ignored. In fact, the quiz is educational once a shooter wraps his head around the general idea that wind at the muzzle produces a different result when compared with wind at the target.

One's initial thought might be to argue that target wind is more significant since the bullet is slower down range and therefore is exposed to the wind for a longer time. I confess, that idea crossed my mind first. But, when studied in the way this interesting quiz is presented, eventually it becomes clear that just the opposite is true.

So while this quiz isn't purely realistic, it does demonstrate to me that when the wind velocity is different at the muzzle than at the target, it would be beneficial to use slightly different amounts of compensation. And, one's initial thoughts about how to cope with different winds might be entirely backwards. In other words, the lessons learned here can indeed be applied in the real world.

 

[6BRinNZ]

So if the near flags are blowing from the right about 6moa worth and the far flags are blowing from the left about 6 moa - what should we do?

Nothing better to wait it out

 

[Geno C]

Funny thing, a place I shoot in mid April is exactly like that! Stiff breeze on your left cheek, chaff in the field blowing good from right to left. Gotta shoot a water bottle at 500.

 

[taliv]

i don't believe any of the three B scenarios are correct as drawn. To the extent shown, the correct diagram would be the first half of the rightmost option B'' (i.e. curved) and the second half of the middle option B' (i.e. straight because the wind does not continue to push it)

because it is straight in the second half, that would maintain the same angular "MOA" value, but only from the perspective of someone viewing it halfway down range. from the perspective of the shooter, at the 1000 yard line, the fact that the bullet is moving in a straight line the last 500 yards would not cause it to maintain the 3 MOA value between 500 and 1000

 

[Olde Man]

Doesn't an object in motion, moving left to right, tend to stay in motion and therefore will not not be a straight line for the last 500 yds?

 

[BLCKWLF]

Doesn't an object in motion, moving left to right, tend to stay in motion and therefore will not not be a straight line for the last 500 yds?

As I show in my diagram I drew, the wind resistance still applies to the air, though static, in the last 500, to slow the left to right momentum of the bullet, creating a reverse curve as the bullet slows it's left to right speed. The forward momentum continues to push the bullet towards the target at a faster speed, this a curve in the second half as well.

 

[FeMan]

Doesn't an object in motion, moving left to right, tend to stay in motion and therefore will not not be a straight line for the last 500 yds?

Taliv has it right. As long as the bullet is subjected to lateral wind loading, its flight path will curve. As soon as it gets out of the wind, it flies straight in the direction it was traveling when the wind quit. The wind, like gravity, is actually accelerating the bullet. The flight paths will be the same; an arc as long as they are experiencing the affects..

 

[taliv]

i just noticed the second half of bullet A should also be a curve as well, same as the back half of B'' except you should draw a line tangent to the curve at 500 yard intersection, and then spin the thing around so that line is vertical (parallel with barrel)

 

[Joe Salt]

If any of you have watched the vapor trail of a bullet it will tell you a lot even in high winds at 1000 yards you can see the bullet correct after about 500 yards. I have watched then arc sometimes that you wonder how they are even hitting the target. But once you are in the bull and watch the vapor trail the bullet curves then comes back to the point of aim and depending on the let up. This is what kills a lot of shooter is they miss the let ups. So the shooter closes to the wall will shoot better, if he is paying attention.I like the steady winds.

Joe Salt

 

[wolley]

I think there will be two curves for bullet B. Yes it had a lateral component when the wind quit. However, that lateral acceleration will continue to decrease as it flies the last 500 yards.

 

[Joe Salt]

Wolley in my years of watching the bullets vapor trail, they resemble a hook or a slice when someone hits a golf ball. I've don't recall an "S" curve they just curve back to the point of aim. I think if they were doing that you would have bad cross wind in both directions.

Joe Salt

 

[FeMan]

I think there will be two curves for bullet B. Yes it had a lateral component when the wind quit. However, that lateral acceleration will continue to decrease as it flies the last 500 yards.

The lateral acceleration stops when the wind stops. With no lateral force acting on the bullet it cannot accelerate or decelerate (there is spin-drift but we aren't talking about that). The lateral velocity that it has accumulated up to that point though is maintained.

 

[Joe Salt]

I think you guys are putting to much thought into this. The bullet will go just to a point to the left or right then has to come back to be able to hit the point of aim. Unless the wind should stop, and that is a let up. That's were most get caught. That mean the bullet is going further left or right. There is no magic the wind is constant or it isn't.

Joe Salt

 

[wolley]

Lateral acceleration is probably the wrong term.
Let me revert to East Texas good ol boy language.
It's moving sideways.