A Wind Chart

H

HuskerP7M8

Renowned Expert/Statistician/Ballistician/Farmer
Feb 4, 2010
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Nebraska
I've been messing around with designing a wind rose or chart that actually describes where the bullet impacts rather than those in the past which only show an exaggerated flight of the bullet with no info for wind velocity.
The problems are creating a chart that's intuitive, but not cluttered with so much info it's hard to use for a quick reference while shooting a match.

This is my latest and I'd like some input on how useful it might be or how I might improve it. Don't be afraid of being critical and it would be very helpful if new or beginning shooters would comment.

Thanks for looking,
Landy

 
Looks nice for sure. I have been using the RFC for USBR one but this is better for ARA. My only question is that the RFC chart shows a drop in impact for a 12 wind and a rise for a 6. In reality for me, a new shooter, 12 and 6 are a problem as there seems to not be any consistency for those two directions so i try and stay away from them. Looking forward to the finished one. I find them to be a good guide to start out with for my sighters. then tweak.

John
 
HuskerP7M8 said:
I've been messing around with designing a wind rose or chart that actually describes where the bullet impacts rather than those in the past which only show an exaggerated flight of the bullet with no info for wind velocity.
The problems are creating a chart that's intuitive, but not cluttered with so much info it's hard to use for a quick reference while shooting a match.

This is my latest and I'd like some input on how useful it might be or how I might improve it. Don't be afraid of being critical and it would be very helpful if new or beginning shooters would comment.

Thanks for looking,
Landy

Click to expand...

There is so often that the bullet does not follow the wind that in truth only the sighter can be relied upon.
That said, when you?ve completed a final version could a .pdf file be made available so a nice clear printout can be created?
Or an original (non compressed) jpeg?
 
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Lapua honestly believes a head or tail wind has no effect on accuracy. I wrote them emails a couple years ago asking.
The calculator says even with a 12mph wind no sight adjustment needed.
Told them I need to shoot in wind like that.
 

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No holes in two quadrants

So regardless of the wind direction, holding center, a hole should not appear in the 12-3 and 6-9 quadrants?
Provided there are no updrafts or downdrafts.
 
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Wind chart

Hi Landy,

That is propably the most accurate as it can be.
First good one since McCoys tests for Olympic grade ammo.
Exactly how I would have hold over.

Br Tomi
 
Landy,
I'm kind of a new shooter, so I'll contribute here. First I will say my wind chart spent less time on my bench and more time in my kit as the 2019 season wore on. I was slowly learning that conditions, which are influenced by wind and many other variables as well, had little to do with what my chart said.

I see no vertical in your 12 and 6 positions. Vertical in one of those positions (12 headwind) is what got me to start not trusting my chart. On a run of the mill chart those (12/6) would be shown as a low/high shot from POA. One club I shoot at, that 12 condition actually pushes the shot high, not low. It does so with remarkable consistency as well. I won a club tourney there once remembering that a topographical feature always pushed a headwind shot high there. Others, some with way more experience than me, were cussing and carrying on about how a bullet could fly into the wind.

After using my chart for several years I got familiar with where the bullet 'should' go (without looking at a chart) and use that information for initial sighters. When those sighters do not go where the chart says they should, I disregard the information I know from the chart and trust my sighters. Not all clubs I have shot have results in POA/POI that go against the chart I used, but enough do that I rarely have a chart on my bench anymore.

Scott
 
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Ballistics programs

Hi,
The question Eidolon makes, is a good one.
In tests where controlled conditions can be had, tailwind can raise the POI, due to
less resistance of air.
But the program can not predict the change of airflow f.ex. over ditches or obstacles
on range. Like the shooting platform, with raised position or roof, which can affect
the wind flow quite a bit. In deed these can be only seen with sighters.

Br Tomi
 
eidolon said:
There is so often that the bullet does not follow the wind that in truth only the sighter can be relied upon.
That said, when you?ve completed a final version could a .pdf file be made available so a nice clear printout can be created?
Or an original (non compressed) jpeg?
Click to expand...

It always, repeat always follows the wind and that chart.
The issues are usually found in two characteristics. The wind is rarely linear from bench to target, and with varying intensities/directions the question becomes an issue of prevailing wind.
Landy's chart should assist new and/or the perpetually wind challenged shooters.....nice job.
As always, the true challenge is to determine which of the, often, various options has the biggest impact on target.
 
HuskerP7M8 said:
I've been messing around with designing a wind rose or chart that actually describes where the bullet impacts rather than those in the past which only show an exaggerated flight of the bullet with no info for wind velocity.
The problems are creating a chart that's intuitive, but not cluttered with so much info it's hard to use for a quick reference while shooting a match.

This is my latest and I'd like some input on how useful it might be or how I might improve it. Don't be afraid of being critical and it would be very helpful if new or beginning shooters would comment.

Thanks for looking,
Landy

Click to expand...

Fantastic chart.
I don't use those charts much now, but they have taught me a lot.
Just one question/remark... why don't you show a correction on tail/head winds?
 
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I think the underlying problem to all of these is that we are trying to apply a 2 dimensional chart to a 4 dimensional problem (I use wind speed as the 4 the dimension). Other than R>L goes generally left and up and L>R goes Left and down with more wind speed, I have never had much luck trying to use a chart.
 
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Thanks Guys,

I really appreciate the input and I'll attempt to address the comments made thus far without getting too technical.

First, there's a very good reason why shooters struggle with a fluctuating head or tail wind like 11:30 to 12:30 and 5:30 to 6:30. It's due to the non-intuitive math used to calculate wind vectors.

You'd think a wind from 45 deg's or the 1:30 position would result in what's called a half value wind as opposed to 90 deg/3:00 where it's a full value wind, but that's not so.
Thru the magic of trigonometry the half value wind is wind is actually at 30 deg/1:00 and not 45 deg/1:30. This means judging the angle of your flags around 6:00/12:00 is much more critical than it is around 3:00/9:00 and it continually gets worse as the wind approaches 6:00/12:00 from perpendicular.

You can see in my chart how the bullet impacts compress as the wind approaches 3:00/9:00 and that means mistakes made in flag angles as the wind becomes perpendicular may not be meaningful, but make the same mistake in a head/tail wind and it'll kill you.
This compression I spoke of would be even more obvious if I had included all of the 15 deg/:30 positions, but then the chart becomes to cluttered, hard to read, confusing, etc.

Even worse, is that there's a vertical component not sensitive to the wind velocity if you're only a few deg's left or right of 6:00/12:00 but non-existent if the wind is always either left or right.
This is due to "Aerodynamic Jump" and the chart in only accurate for a 16" twist barrel at the 50 yd/meter distance.

Second, the absence of any vertical in my chart for head vs tail winds. This vertical pretty much gets lost in the noise unless we're shooting with some very strong winds and my chart is for only 5 mph. I wanted to make a chart that included 5, 10, and 15 mph but it was just a mess with all the additional info. If the chart were for a 15 mph wind, the straight line of impacts would form an ellipse with the minor (vertical) and major (horizontal) axes of the ellipse centered on the dot.

Look at it this way, a 5 mph wind is only 7 fps and out of tens of thousands of rds in my ballistic tunnel I've never seen a velocity Standard Deviation consistently below 5 fps. With an SD of 5 fps, we'll have an Extreme Spread in velocity of 30 fps 99.7% of the time, and even with a 30 fps ES it took me hundreds of rds of data to prove it statistically existed at even the 1 sigma level.

I also want to reemphasize the chart will change, and sometimes dramatically, if it's made for different velocities and different distances. I'm simply unable to incorporate everything I originally hoped I could, but I think a 5 mph chart at 50 yds/meters is a decent compromise for the majority of times we shoot if you factor in that most shooters over exaggerate the wind velocity like they under exaggerate the groups they shoot. LOL

Landy
 
As a true newby, I like the chart. But, I've also seen variations in 12&6. Thank god, I've not seen r-l yet. It's hard enough to track l-r. Thanks Landy, the chart is truly readable.
 
doclu60 said:
Landy,
I'm kind of a new shooter, so I'll contribute here. First I will say my wind chart spent less time on my bench and more time in my kit as the 2019 season wore on. I was slowly learning that conditions, which are influenced by wind and many other variables as well, had little to do with what my chart said.

I see no vertical in your 12 and 6 positions. Vertical in one of those positions (12 headwind) is what got me to start not trusting my chart. On a run of the mill chart those (12/6) would be shown as a low/high shot from POA. One club I shoot at, that 12 condition actually pushes the shot high, not low. It does so with remarkable consistency as well. I won a club tourney there once remembering that a topographical feature always pushed a headwind shot high there. Others, some with way more experience than me, were cussing and carrying on about how a bullet could fly into the wind.

After using my chart for several years I got familiar with where the bullet 'should' go (without looking at a chart) and use that information for initial sighters. When those sighters do not go where the chart says they should, I disregard the information I know from the chart and trust my sighters. Not all clubs I have shot have results in POA/POI that go against the chart I used, but enough do that I rarely have a chart on my bench anymore.

Scott
Click to expand...

We were shooting at Oak Ridge on a very nice day a couple of years ago. The wind was sustaining at least 12 mph and gusts to 25 mph. A very good and well-known shooter was on his way to another match and just stopped and to shoot that one. He shot a 2250 in those conditions and I think the next highest was about 1700 and then it was more like 1300 for the rest. I asked him how he managed that. He said "I just saw a headwind and I would hold around six o' clock for that". Contradicts what you think you know doesn't it? Try it, he's right.
 
eidolon said:
So regardless of the wind direction, holding center, a hole should not appear in the 12-3 and 6-9 quadrants?
Provided there are no updrafts or downdrafts.
Click to expand...
Hi Ralph,

If I'm understanding correctly, that's right. However, if I'd have included 11:30, 12:30, 5:30, and 6:30 in the chart...a large portion of the bullet hole would be in those quadrants.

Landy
 
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