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**<< Mentor Note:Thread moved from the Homework forums because it isn't really about homework >>**

Preface

Preface

With my limited understanding of physics, I am unaware of what section of the forums this question would fall into. I am not doing this for school(though possibly it might help with that in the future), however, it is work that I am doing from home, so I put it here. I apologize for any inconvenience this may cause, and feel free to move this thread or ask me to move it to a more appropriate location.

Goal

Goal

My goal is to convert said equation(s) into excel format, given known variables of velocity in feet per second(measured with chronograph), altitude in feet above sea level, temperature in degrees Fahrenheit, twist rate in inches per turn, bullet diameter in inches, bullet length in inches, bullet mass in grains, and barometric pressure in in/Hg

All units above are known to be in standard measurement for the equation, other than barometric pressure, temperature, for which a conversion may be needed for all I know.

In the process of completing this integration into excel format, I hope to come to better understand the equation not just in terms of creating a variable to use in a spin drift calculation, but truly understanding the equation, why it is the way it is, and the accuracy I can expect out of it.

As far as the practical application, I have developed calculators in excel format for wind drift, spin drift, hold on moving targets, and bullet drop. I am also working on a calculator for compensating for the Coriolis Effect, however I have not researched that enough at this moment to feel right asking questions about it... though so far it has been the most exciting to research. I plan on compiling these calculators into one master calculator that, in environmental conditions that muzzle velocity and ballistic coefficient has been tested in, given relevant information, the calculator will simply give you an adjustment for your optic to match your point of aim to your point of impact.

As far as the why? I view shooting as an art and science, at a certain performance level everything goes into it from your mind and body, to the care which you took in selecting components for your rifle, and the care taken in it's assembly and maintenance, to the same care taken with your optic(though I do not assemble my own) and your ammunition. I see a well placed shot as the proof of mental clarity, attention to detail, responsible action, skill and knowledge.

1. Homework Statement

1. Homework Statement

solve for "s", incorporating corrections for velocity and air density

## Homework Equations

I don't have the equation for how to get air density from the environmental conditions, as far as I know. I have f(a)= e^(3.518x(10^-5)+h), but I don't know how that can be used with the other equation(s), essentially where to plug it in or what I am missing if I am missing anything.

## The Attempt at a Solution

I know how to balance the equation to have it solve for "s", but I do not know how to implement the corrections, as I recall from school almost 8 years ago, if f(a)=1, and f(c)= a+2, then I plug in 1 for a and get f(c)=3... or something like that. here though, I think it might possibly be that simple but the format is confusing me.

**Sources/reference material**

PDF file on article regarding the comparison of various models for calculating stability factors

PDF file on article regarding the comparison of various models for calculating stability factors

http://www.jbmballistics.com/ballistics/bibliography/articles/miller_stability_2.pdf

**Calculator that does exactly what I am trying to do**

http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

**The next step**

I currently use the calculator above to get my stability factor, then use that and time in flight to calculate spin drift at the target range, however I do not know if this accounts for loss in angular velocity due to drag, after I find that out, which should come with understanding the above equations, I may choose to make a more accurate method of calculating spin drift, by adjusting for that loss in angular velocity of the bullet per yard at every range up to the target range, then add the drift of every yard line together to form the total drift at target range. I am thinking the equations for remaining velocity and time in flight could possibly come in handy but I will cross that bridge when I come to it.

My end results I plan on posting here, as I am sure it would be of use to someone trying to do the same thing I am doing, and because if anyone wants to check my work for errors and finds any, that would be of great benefit to me.

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