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Wind value tool

Fast14riot

Fast14riot

Gold $$ Contributor
After watching some interviews with Emil Praslick on wind reading for long range, I took his simplified version of the sine values for wind affect based on angle and made myself a little tool to help me remember.

How it works, zero points at the target, move pointer to match your wind direction. The closest number is the percent of full value wind on your bullet. Its made from white acrylic so I can write my values for the day in dry-erase marker for whatever gun and distance I'm shooting.

20210630_162053.jpg
 
Fast14riot said:
After watching some interviews with Emil Praslick on wind reading for long range, I took his simplified version of the sine values for wind affect based on angle and made myself a little tool to help me remember.

How it works, zero points at the target, move pointer to match your wind direction. The closest number is the percent of full value wind on your bullet. Its made from white acrylic so I can write my values for the day in dry-erase marker for whatever gun and distance I'm shooting.

View attachment 1264277
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That’s very interesting. The way you have it divided up I would have thought the 75% value would be the 50% value in my mind.
 
Kracken McGraw said:
That’s very interesting. The way you have it divided up I would have thought the 75% value would be the 50% value in my mind.
Click to expand...

Its a sine function, so 30° is 50% of full value. The only built in error on this is going to be at 60° (2 o'clock) and 75° (2:30 o'clock), with actual values being 87% and 96%, which a 3% error is well within mine or anyone else's ability to read wind speed. The 90% and 95% is just easier math.
 
Fast14riot said:
Its a sine function, so 30° is 50% of full value. The only built in error on this is going to be at 60° (2 o'clock) and 75° (2:30 o'clock), with actual values being 87% and 96%, which a 3% error is well within mine or anyone else's ability to read wind speed. The 90% and 95% is just easier math.
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Great Information!
 
Here is a simple visual for those struggling with the mental math of 30° = 50%.

Its a vector component. The length of the Y axis is the wind speed, in our example its 10mph, and for simplicity its not changing speed as it clocks around. So when I take a line 30° from vertical (0%) the same length (because length = wind speed) the value of the component is 50% of full value.20210630_185417.jpg
 
I love the idea! I have never understood how much to allow for wind. My issue is if all flags are pointing the same direction I see this working. But I get lost when 4 flags are doing 4 different things... how do you then know how much value to use?
 
cheek9075 said:
I love the idea! I have never understood how much to allow for wind. My issue is if all flags are pointing the same direction I see this working. But I get lost when 4 flags are doing 4 different things... how do you then know how much value to use?
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Well, you have discovered the "art" of wind reading! Personally I look at wind at 1/3 and 2/3 range primarily. In F/class with target pits, you have the advantage of holding off from shooting during a wind condition you dont quite understand and can watch the target spotters come up, usually in one general direction. I'll usually focus my spotting scope around 2/3 and will use my eyes for 1/3.

Now, most ranges will have a prevalent wind direction, and there will be rolling gusts, shifts, let-offs and switches. They will usually follow a periodic cycle, rolling down or across the course. This is usually found by watching during scoring and prep. Basically, always watch the wind. Always.
 
The real world application: my 260AI required 0.5moa wind per mph at 1000y. Knowing this, I just get a reading on the wind speed. Say its 13.2mph. Notice I don't care about direction, just speed. So, 13.2x0.5 = 6.6moa at full value. Now all I need to write down is my moa per mph wind speed at that distance. I can use the dial to calculate how much to dial or hold, in practice its a combination of both, dial in for the prevelant condition and hold for various shifts.
 
In my experience over the last 25 years, I’ve learned the wind doesn’t stay the same long enough to be looking at a chart and back to the flags and to the rifle and back to the target. A part of learning the wind is remembering what it does to the bullet in flight. I only shot 100-200 centerfire bench rest up until this year and believe me when I say that this experience has helped me tremendously this year as I took up 25 meter air rifle. Those damned pellets will get pushed all over the place and the Ten and X rings are mighty small. At any rate, as I see it, these training aids are all fine well and good for practice and practice sessions but in the real world learn your rifle, your ammo, the wind and then remember it. In bench rest you have the luxury of having your four or five flags right under the line of the bullet flight and you can see your flags in real time if you have properly placed your flags. Take as much time as you can when placing your flags.
 
This is why I like shooting matches in switchy headwinds. Things go from zero to 50 faster than a dragster and you better be in your toes. Most people don't understand trig or how fast the lateral component builds. If you get a gusty head wind that's switching, watch out!!
 
If you think about it a bit, and refer to the chart, near to a cross wind you need to pay more attention to velocity than slight differences in angle. On the other hand near to a head or tail wind the opposite is true, you need to be more concerned about angle than velocity.
 
SPJ said:
Ya got any 6mm bullets for sale ?
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Sadly, I'm down to my last few hundred jackets that aren't spoken for until spring. Things are rough out there. I still have a fair number of .30 jackets, though.
 
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The point of this tool is to fill in the bookends of wind speed and directions for a given string of fire, not to be consulted for every single shot. But, it is handy to remind yourself for what value is needed based on direction.
 
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