Wind Reading

[NV Highpower]

this is an app that I've been thinking about writing for some time and I finally got around to building it...

the app is intended to be a training aid for mid and long range shooters to help understand the effects of wind and the trade-offs to consider when evaluating wind direction and velocity. As a visualization tool, you can use it to play with wind scenarios. The app also doubles as a shot plotting and wind plotting tool. I know a lot of people out there are vehemently against plotting and record keeping, and I respect that, but for those who do plot, check it out.

https://accuracysoftware.com/high-power-wind-lab

If you have an feedback, questions or feature requests, please let me know. Available now for both android and ios devices...

 

[CaptainMal]

For iPhone and iPad. Hope you sell a bunch.

 

[NV Highpower]

For iPhone and iPad. Hope you sell a bunch.

Me too! Thanks for the encouragement!

 

[Bart B.]

You might want to include this information:

 

[NV Highpower]

You might want to include this information:

View attachment 1088620

that's great information, thank you for sharing.

 

[Bart B.]

The old military wind formula developed a century ago for the 30-06 would get you on paper most of the time.

"Range in hundreds hundreds of yards times wind speed in mph divided by 10 (their wind constant) equals full value wind at 3 or 9 o'clock n MOA correction. Winds at 1, 2, 4, 5, 7, 8, 10 and 11 o'clock are half value winds. Could be a few MOA off as it's based on the wind speed being the same at all ranges. Better than nothing.

With ballistic software and reverse math, a custom formula for your load could be established for each range and be very accurate if each clock hour was used. Each load will have a different wind constant for each range.

 

[NV Highpower]

The old military wind formula developed a century ago for the 30-06 would get you on paper most of the time.

"Range in hundreds hundreds of yards times wind speed in mph divided by 10."

With ballistic software and reverse math, a custom formula for your load could be established for each range and be very accurate.

Yeah - a lot can be done. I've written a ballistics solver and thought about including it in this app, but I decided to not include it so you can use the ballistics software of your choice and input the results. that way everything you've calculated will line up with the results this app produces.

 

[Bart B.]

Yeah - a lot can be done. I've written a ballistics solver and thought about including it in this app, but I decided to not include it so you can use the ballistics software of your choice and input the results. that way everything you've calculated will line up with the results this app produces.

Thanks for planning to do all the right stuff.

 

[Depart123]

The old military wind formula developed a century ago for the 30-06 would get you on paper most of the time.

"Range in hundreds hundreds of yards times wind speed in mph divided by 10 (their wind constant) equals full value wind at 3 or 9 o'clock n MOA correction. Winds at 1, 2, 4, 5, 7, 8, 10 and 11 o'clock are half value winds. Could be a few MOA off as it's based on the wind speed being the same at all ranges. Better than nothing.

With ballistic software and reverse math, a custom formula for your load could be established for each range and be very accurate if each clock hour was used. Each load will have a different wind constant for each range.

It's easier I think, to just find the wind that pushes your load 1/2 moa per hundred and adjust from there as needed for actual wind speed and direction. That way you just end up dealing with simple percentages of a single number that is tailored for your rifle.

 

[Bart B.]

It's easier I think, to just find the wind that pushes your load 1/2 moa per hundred...

Is wind drift that linear through 1000 yards when bullet speed at 1000 is less than half that of muzzle velocity?

 

[Depart123]

Is wind drift that linear through 1000 yards when bullet speed at 1000 is less than half that of muzzle velocity?

If your bullet is still supersonic at 1000 yards it will be within 1/4 moa of the prediction to 1000.

The wind drift of the bullet isn't linear, it is parabolic. But within the supersonic range of the pointy bullets most of us are shooting, the difference is small enough to be incosequential.

 

[Bart B.]

JBM stuff says 5.5 mph wind at 9 for a 30 caliber 168, .477 G1 BC, leaving at 2700 has .4 MOA wind drift at 100 yards and 5.67 MOA at 1000. A 5.27 MOA change over 900 yards.

.585 MOA average change per 100 yard change. Right?

 

[NV Highpower]

without trying to be too self promotional, its these kinds of questions that my app tries to answer for shooters. The app takes as its input the 10 mph full value (90 degree) correction for your load and then shows you the correction for any wind direction (360 degrees) and velocity between 0 and 20 mph. It also shows you an error range on a target if you misjudge the wind velocity or wind angle up to 1.5 mph and 15 degrees respectively. If you're familiar with midrange and long range high power target (f-class or target rifle) then the corrections will make sense to you. If not, the bull on a 1000 yard LR target is 10 inches or approximately 1 MOA for reference.

 

[fyrewall]

You might want to include this information:

View attachment 1088620

View attachment 1088621

Unable to locate reference - seems like skimming a bullet over rough stuff or objects will result in less deflection. Derivation of the exponent value "^n" is unknown - this sort of sounds like airplane stuff, "Many trees in suburbs" - wind shear. This could have some application for my, low to the ground, casual shooting over rock piles, stumps, sage brush, and other features.

I use the Hornady 4DF calculator (no consideration for terrain), with my notes and have favorite spots to shoot from and at.

 

[Depart123]

JBM stuff says 5.5 mph wind at 9 for a 30 caliber 168, .477 G1 BC, leaving at 2700 has .4 MOA wind drift at 100 yards and 5.67 MOA at 1000. A 5.27 MOA change over 900 yards.

.585 MOA average change per 100 yard change. Right?

I ran your numbers at sea level, and a 5mph wind gives 4.9 moa at 1K yards. Running a low BC bullet and running it that slow, increases the deviation at midrange to 0.5 moa from the 1/2 moa per hundred rule.

So at 600 yards you are at 2.5 moa drift rather than 3 moa drift. But still, using 1/2 moa per hundred in your scenario still keeps you to within 1/2 moa of actual drift all the way to 1K yards. And at the farther ranges, 7,8,9 and 1K, where it is most important, the prediction becomes increasingly accurate.

At 2,000 ft elev. you gain 0.5 mph (5.5 mph)for the same effect. 4,000 ft elev. gets you another 0.5 mph (6mph)

 

[Bart B.]

Unable to locate reference - seems like skimming a bullet over rough stuff or objects will result in less deflection. Derivation of the exponent value "^n" is unknown - this sort of sounds like airplane stuff, "Many trees in suburbs" - wind shear. This could have some application for my, low to the ground, casual shooting over rock piles, stumps, sage brush, and other features.

I use the Hornady 4DF calculator (no consideration for terrain), with my notes and have favorite spots to shoot from and at.

I didnt know Aerostar's web site no longer has that link info. The link below explains:

https://en.wikipedia.org/wiki/Wind_gradient

 

[Bart B.]

I ran your numbers at sea level, and a 5mph wind gives 4.9 moa at 1K yards. Running a low BC bullet and running it that slow, increases the deviation at midrange to 0.5 moa from the 1/2 moa per hundred rule.

So at 600 yards you are at 2.5 moa drift rather than 3 moa drift. But still, using 1/2 moa per hundred in your scenario still keeps you to within 1/2 moa of actual drift all the way to 1K yards. And at the farther ranges, 7,8,9 and 1K, where it is most important, the prediction becomes increasingly accurate.

At 2,000 ft elev. you gain 0.5 mph (5.5 mph)for the same effect. 4,000 ft elev. gets you another 0.5 mph (6mph)

Very interesting. But I use the shooters MOA standard because its exact and target rings are based on inch spacing. So does the IBS benchrest discipline.

"Aggregates for group shooting at 100, 200 and 300 yards are calculated in approximate Minutes of Angle (1 inch = 1 MOA at 100 Yards)."

 

[Depart123]

Very interesting. But I use the shooters MOA standard because its exact and target rings are based on inch spacing. So does benchrest disciplines.

Exact same process. It's the method, not the angle or unit of measurement you use. Using shooter's MOA (inches / per 100 yards) the wind is adjusted to 4.8 mph at sea level to achieve same result. So, essentially identical.

 

[Bart B.]

Exact same process. It's the method, not the angle or unit of measurement you use. Using shooter's MOA (inches / per 100 yards) the wind is adjusted to 4.8 mph at sea level to achieve same result. So, essentially identical.

Thanks for this enlightening education in wind doping. There's several ways to skin a cat. Never heard of this one.

Biggest wind correction I ever put on to start was for the first sighter at 800 yards with a 308 shooting 148 grain bullets. 28 MOA left put me on paper 2 feet left of call.

 

[Depart123]

Thanks for this enlightening education in wind doping. There's several ways to skin a cat. Never heard of this one.

Biggest wind correction I ever put on to start was for the first sighter at 800 yards with a 308 shooting 148 grain bullets. 28 MOA left put me on paper 2 feet left of call.

So, about 40 mph winds?