By way of the always-stimulating 10-8 Forums, I found this fascinating discussion of the mechanics of the “mil” and its cousin the “MOA.” (See the link in the first post.)
For the uninitiated, both are units of angular measurement useful in military operations. The mil is the basis for fire support tasks but it can be used for other things as well. The MOA is critical to understanding how most rifle sights and scopes work. Both, as I said, are quite useful because they can produce a unit of width for any angle at a given number of the same unit of linear measurement. The end result is that you can do neat things like, say, predictably move the impact of your rounds.
OK, yes, there are truly 6283 mils in a circle, but we use 6400– that’s “six-four-hundred” to you– because it’s easier to divide. And really, a mil is only about a seventeenth of a degree, so WTF? Go read and heed. Some of the math made my head hurt, but it’s worth the time to save and print.
OK, yes, there are truly 6283 mils in a circle
No, there aren’t (pi is an irrational number), and that doc makes a few mistakes. I’ll try and set things straight when I get back from work.
I derived the range estimation algorithm myself a while back and you need to use the small sine rule to do it. (sin(x) = x for small values of x…)
DAMMIT, BEAVIS! Or rather, SCOOBY… that’s the kind of thing that makes my head hurt. :-) Bottom line is that both are useful little formulae even which they’re used in their less than perfect forms, e.g. the mil-relation formula commonly called the “WERM rule.”
Heh. When I went before the Staff Sergeant Board, most of the panel was Ground Surveillance Radar NCOs. (I was SIGINT.) The actual GSR Company First Sergant said “Damnit, Sergeant Major, we all know SGT Drang’s good, let’s just give him a 199 {score, out of 200, max is unheard of} and go to lunch.”
“Now, Top, you have to ask him a question.”
“Fine, SGT Drang, what’s the back azimuth of 6400?” Which he almost got me on, because, being a SIGINT Geek, I use degrees, not mils, for direction finding. But there’s another consideration: “Is that in NATO Mils, or commie mils, First Sergeant?”
The Bad Guys use a 6000 mil circle…
Even if there are minor inaccuracies in the info, as a former infantryman, so long as we are within the bursting radius of a 155mm round and can fire for effect, we’re close enough. Plus, there’s the unit of measurement, the “skosh”, as in, “just a skosh left”.
This is truly the stuff Gunnery Instructors in Grpville live for. Hallelujah for MLRS!
I derived the range estimation algorithm myself a while back and you need to use the small sine rule to do it. (sin(x) = x for small values of x…)
Bottom line is that both are useful little formulae even which they’re used in their less than perfect forms, e.g. the mil-relation formula commonly called the “WERM rule.”