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Advanced Marksmanship Wind angle
- Thread starter ForgeValley
- Start date
D
Deleted member 113831
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I like the zero's also.
As a practical change to method, all it means is that your finger slides out from center to either 90* or 270* rather than 0*.
As a practical change to method, all it means is that your finger slides out from center to either 90* or 270* rather than 0*.
Greetings all!
This is "Greekman", an old member, that drops by from time to time to catch up.
Way back then I posted a practical method of calculating wind value, which I will repeat here.
(Admirably the 'Hide has progressed a lot on practical ballistics)
How to Calculate Wind Values with your Compass (or Protactor)
The goal is to calculate a wind angle correction with simple means, no printed data books, and no trigonometry!
But to do that one has to understand some trigonometry.....
The key is to understand that sine and cosine values are projections of the (wind) force on the X and Y axis.
Have a look at this pic:
What I have done is plot the two axis on a piece of paper. Both are the same length, 40mm, but you can use any length, the longer the better.
I assumed that the wind comes from 2 o'clock, which is 30 degrees off the horizontal.
Then I used my compass to plot the wind force vector at the angle it comes from, again 40mm long. Equal length of is Important.
What is left to do is to project the wind "vector" on the X axis to get the correction value.
So we get 34 out of 40 = 0.85 or 85%
and
Cosine of 30 degrees = 0.8660
And this is a half done Wind Rose, based on my method.
It has a generic scale drawn and a wind value scale every 15 degress of angle.
One can have a blank wind rose like this and draw wind lines as needed when in the field.
Here is how the method is applied to the "corrected Lowlight's wind rose"
You can put a ruler on your screen to verify yourself.
And riifraff's wind rose is very close to my method.
A wind that comes at 30 degrees off the bore axis will have a value of 0.5, right?
Well, in this wind rose, it drops right in the middle of the 10 squares riffraff has drawn!
And what about a 2 o'clock wind?
It drops right in the middle of square no9, and is eyeballed at 0.85!
Just as simple as reading distances on a map!
Hope you found it of use....regards!
This is "Greekman", an old member, that drops by from time to time to catch up.
Way back then I posted a practical method of calculating wind value, which I will repeat here.
(Admirably the 'Hide has progressed a lot on practical ballistics)
How to Calculate Wind Values with your Compass (or Protactor)
The goal is to calculate a wind angle correction with simple means, no printed data books, and no trigonometry!
But to do that one has to understand some trigonometry.....
The key is to understand that sine and cosine values are projections of the (wind) force on the X and Y axis.
Have a look at this pic:
What I have done is plot the two axis on a piece of paper. Both are the same length, 40mm, but you can use any length, the longer the better.
I assumed that the wind comes from 2 o'clock, which is 30 degrees off the horizontal.
Then I used my compass to plot the wind force vector at the angle it comes from, again 40mm long. Equal length of is Important.
What is left to do is to project the wind "vector" on the X axis to get the correction value.
So we get 34 out of 40 = 0.85 or 85%
and
Cosine of 30 degrees = 0.8660
And this is a half done Wind Rose, based on my method.
It has a generic scale drawn and a wind value scale every 15 degress of angle.
One can have a blank wind rose like this and draw wind lines as needed when in the field.
Here is how the method is applied to the "corrected Lowlight's wind rose"
You can put a ruler on your screen to verify yourself.
And riifraff's wind rose is very close to my method.
A wind that comes at 30 degrees off the bore axis will have a value of 0.5, right?
Well, in this wind rose, it drops right in the middle of the 10 squares riffraff has drawn!
And what about a 2 o'clock wind?
It drops right in the middle of square no9, and is eyeballed at 0.85!
Just as simple as reading distances on a map!
Hope you found it of use....regards!
Last edited:
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