Ballistic Software and Wind

[AWLEAPHART]

I did a search about reading wind flags and found a chart showing bullet path with a right hand twist on your barrel. The path showed the bullet rising with wind from the right and the bullet dropping with wind coming from the left. I have two different ballistic software on my iPhone and when setting up wind its doesn't raise or lower the vertical. I was wondering if I am missing something?
Anthony

 

[dcali]

There is a phenomenon called aerodynamic jump, which is what happens when there is a disturbance of the bullet at the muzzle. Wind, among other things, can cause it. Because of the gyroscopic properties of the spinning bullet, a sideways disturbance causes vertical dispersion. This effect is small, and is not accounted for by most ballistics calculators. There are several that do, however.

 

[DocUSMCRetired]

You need to find Ballistic Calculators that account for Aerodynamic Jump. Applied Ballistics Does.

 

[mikecr]

https://en.wikipedia.org/wiki/Magnus_effect#In_external_ballistics

 

[SheepDog]

Doc is right, you need a 6 degree of freedom software to account for the smaller effects of magnus and coriolis (both vertical and horizontal).

 

[dcali]

It's not Magnus. It's a subtle technical point, but AJ is a different thing entirely. The Magnus force is just that - a force (a very small one). Aerodynamic jump is a change in direction. AJ is why good bullets are better than bad bullets - it's one of the primary drivers of rifle dispersion. People know it better as this obscure vertical wind effect, but it really is much more than that.

You can calculate aerodynamic jump with a few methods, ranging from the method that AB uses, to modified point mass calculator, to full blown 6DOF calculator, and each has it's pluses and minuses. At the end of the day, just being aware of it is generally enough in my view, as it's a tricky thing to nail down.

 

[AWLEAPHART]

This is very educationl
Anthony

 

[AWLEAPHART]

I already have a ballistic software with a wind meter set up so I was wondering can I mathematically figure the vertical jump?
Anthony

 

[dcali]

Not really - the math is complex and it requires data that you typically will not have. The easiest way is to use the ballistics calculator. Applied Ballistics does it, as does the new Hornady "4DOF" calculator. There may be others as well - I don't really keep up to speed on the latest calculators.

It's not a terribly large factor except at short range, and then it's only something benchrest shooters care about. A rule of thumb at 100 yards is one click up/down for every four or five to the side, so you need a really accurate rifle and a stiff wind to see it. At long range it's more like 1:15 or 1:20 - barely noticeable, as it gets swallowed up by larger problems.

 

[CharlieNC]

At long range instruction I was told the vertical adjustment for compensation is approx 15% of the wind adjustment. That was close at 800 to 900yd.

 

[AWLEAPHART]

Thanks a lot everyone
Anthony

 

[jcampbellsmith]

You need to find Ballistic Calculators that account for Aerodynamic Jump. Applied Ballistics Does.

Not the Android version. Still waiting for this feature some 2+ years on from asking the question.

Android version last updated on 5 Jun 2015.

Regards JCS

 

[DocUSMCRetired]

Not the Android version. Still waiting for this feature some 2+ years on from asking the question.

Android version last updated on 5 Jun 2015.

Regards JCS

Android version was updated a couple weeks ago. Some updates that we perform on the back end, do not require you to download a new version. You are correct, AJ is not in the Android version of AB Mobile yet.

 

[jcampbellsmith]

Android version was updated a couple weeks ago. Some updates that we perform on the back end, do not require you to download a new version. You are correct, AJ is not in the Android version of AB Mobile yet.

and is there a plan now to add AJ to the Android version? Thanks JCS

 

[Derrick]

Software and computer generated input isn't going correct for this. Magnus force mentioned above, Shooting with a right hand twist barrel, with wind coming from the left to right will have turbulence below the projectiles center of pressure will shift the nose of the projectile up(destabilizing). Then wind coming from right to left will push the projectiles nose down(stabilizing). Magnus force should be looked at. But I have know idea how much it matters.