Metric trajectory correction formula

[PRCslut]

I am trying to find a trajectory correction formula for metric units and mrad. I have no problem finding a mrad formula where it butchers mrads with inches and yards.

Mrads and centimetres and meters

 

[Hookturnr]

 

[Hookturnr]

 

[Skeptic1]

Please not this again

 

[sirhrmechanic]

Prefer beer over Mead, but in a pinch, I’ll quaff the odd firkin of Mead.

But curious about the trajectory formula. Is this in case you projectile vomit? Or is it for throwing your horn of Mead at the head of an enemy who invades your drinking Longhouse?

Sirhr

 

[sirhrmechanic]

We almost had the formula, but then our funding was cut…

Sirhr

PS. OP… Maybe re-ask this in the proper area? ELR or reloading or some place other than the pit? Because… you see what happens! And it would even have happened if your spelling was not Mead-addled!

 

[supercorndogs]

Since you already seem to be trying make something simple, so much more difficult. I think your best option might be to switch to MOA.

 

[Rthur]

FFS.....

That is all.


R

 

[HPIguy]

If you aren't smart enough to change an app or device over to metric units, this is gonna be a challenging hobby for you.

 

[Pbgt]

Tell us you shoot 6.5 cm, without saying you shoot 6.5 cm....

 

[Eostech]

There probably isn't a ballistic solver that doesn't have MRAD..

 

[The D]

You need to gyoogle “angle of the dangle”

 

[Ledzep]

How many times do we have to do this.
Radians aren't metric. A radian is simply a unit of measurment.View attachment 8622642

While the linear units used with angular measures tend not to be critical for practical application, Radians are, in fact, the standard SI/metric angular unit.

 

[smoothy8500]

Mrads and centimetres and meters

Just when they finally quit engraving elevation knobs with " click = 1 cm/100meter" so Americans would buy their scopes....

 

[TheHorta]

Do you even Kentucky Windage, bro?

 

[supercorndogs]

While the linear units used with angular measures tend not to be critical for practical application, Radians are, in fact, the standard SI/metric angular unit.

I hear they cut pies into slices across the pond too.

 

[Nik H]

OP is from Canada

Didn't know they could still own firearms up there let alone scoped firearms

 

[Sniperwannabee]

I am trying to find a trajectory correction formula for metric units and mrad. I have no problem finding a mrad formula where it butchers mrads with inches and yards.

Mrads and centimetres and meters

 

[sirhrmechanic]

Changing the tread title, eh?

We know how this started!!!

Sirjr

 

[DarnYankeeUSMC]

All the metric countries are using metric sockets on a 1/4, 3/8 and 1/2 inch ratchets.

 

[Mike Casselton]

This is why our snow Mexicans are confused. They can't even make up their mind on how to spell meter/metre/meat her.

 

[alpine44]

I hear they cut pies into slices across the pond too.

Think of a radian as the angle of a pizza slice where the straight sides are as long as the curved side.

The entire pizza has a radius r, which is also the length of the straight sides of each slice
The circumference of that pizza is 2*pi*r

If we now divide the 360 degrees of the pizza by 2*pi, then we get the approximate degree value of 57.3 degrees per radian.
By using 2*pi as the divider for the arc, we avoid a conversion constant between angle and arc length.

The beauty of the SI system is not only that each unit itself is on a decimal scale (rather than 12 inch in 1 foot, 5280 feet in a mile, etc.) but more importantly that the different units correlate in a physically meaningful way.
You'll appreciate this once you have to deal with electrical charges, viscosity, magnetism, etc. where the Imperial system becomes an insane mess.

 

[hlee]

Wait, what? Where are there 6000 feet in a mile. Them’s small foots.

 

[CoryT]

Attoparsecs per furlong is the answer. Elegant in it's simplicity.

 

[alpine44]

Wait, what? Where are there 6000 feet in a mile. Them’s small foots.

Corrected. (I was thinking about my introduction into the mile high club, leveled out at 6000' or approximately 1 nautical mile.)

 

[Gemsbok]

@hlee 6076.12 ft/NM

 

[Rthur]

Wait, what? Where are there 6000 feet in a mile. Them’s small foots.

That is semen/seamen specific...

R

 

[mtrmn]

Think of a radian as the angle of a pizza slice where the straight sides are as long as the curved side.
View attachment 8623152
The entire pizza has a radius r, which is also the length of the straight sides of each slice
The circumference of that pizza is 2*pi*r

If we now divide the 360 degrees of the pizza by 2*pi, then we get the approximate degree value of 57.3 degrees per radian.
By using 2*pi as the divider for the arc, we avoid a conversion constant between angle and arc length.

The beauty of the SI system is not only that each unit itself is on a decimal scale (rather than 12 inch in 1 foot, 5280 feet in a mile, etc.) but more importantly that the different units correlate in a physically meaningful way.
You'll appreciate this once you have to deal with electrical charges, viscosity, magnetism, etc. where the Imperial system becomes an insane mess.

Yeah but it's MY insane mess.

 

[DocRDS]

Metric conversion:
2.54 cm = 1 inch (exactly--its actually the definition of the inch)
2 * Pi * 1000 milliradians = 360 degrees = 1 circle.

Because angles are ratios, they have no dimensions of length, they are independent of the measuring system.

arc length (vertical distance) is expressed as angle x radius (of the circle containing the arc, aka "distance to target"). There are pi/180 radians per degree.

So if you want measurements from degrees (MOA) its just (pi/180)*distance. If you want meters , plug in the distance in meters, yards, plus in the distance in yards.

If you want measurements from radians (MIL) its just angle*distance. Again, plug in the distance in your units.

THis assumes you can convert from milliradians to radians and cm to m and inches to feet (which is actually like super hard man)

ANd you bitches made fun of me for paying attention in math.

And for the astute among you yes, the arc length is not the same as the vertical distance. But its like super super close (I think at 100y the difference is in the 4th decimal point).

 

[Makinchips208]

And for the astute among you yes, the arc length is not the same as the vertical distance. But its like super super close (I think at 100y the difference is in the 4th decimal point).

Sort of, kinda. But it’s more like, as the angle increases then the difference becomes greater.
Regardless if it’s an inch or a mile. Ratios.

I think @Aftermath could word it better than me.


But in rifle scopes it doesn't matter at all. So effectively, you are correct.

 

[The D]

Metric conversion:
2.54 cm = 1 inch (exactly--its actually the definition of the inch)
2 * Pi * 1000 milliradians = 360 degrees = 1 circle.

Because angles are ratios, they have no dimensions of length, they are independent of the measuring system.

arc length (vertical distance) is expressed as angle x radius (of the circle containing the arc, aka "distance to target"). There are pi/180 radians per degree.

So if you want measurements from degrees (MOA) its just (pi/180)*distance. If you want meters , plug in the distance in meters, yards, plus in the distance in yards.

If you want measurements from radians (MIL) its just angle*distance. Again, plug in the distance in your units.

THis assumes you can convert from milliradians to radians and cm to m and inches to feet (which is actually like super hard man)

ANd you bitches made fun of me for paying attention in math.

And for the astute among you yes, the arc length is not the same as the vertical distance. But its like super super close (I think at 100y the difference is in the 4th decimal point).

 

[Nik H]

I came across this thread just now.

I have read the OP's question twice and still have no clue what he wanted to know.

What is a "trajectory correction formula for metric units and mrad?"

I just have to laugh

 

[half]

If I’m shooting from a boat, do I change my velocity to knots?

 

[alpine44]

Sort of, kinda. But it’s more like, as the angle increases then the difference becomes greater.
Regardless if it’s an inch or a mile. Ratios.

I think @Aftermath could word it better than me.


But in rifle scopes it doesn't matter at all. So effectively, you are correct.

The error in % is indeed independent of distance.
Here are the numbers:

 

[TicTacTex]

If I’m shooting from a boat, do I change my velocity to knots?

How else do you think SEAL team 6 made those shots and saved Captain Phillips?

 

[DocRDS]

Sort of, kinda. But it’s more like, as the angle increases then the difference becomes greater.
Regardless if it’s an inch or a mile. Ratios.

I think @Aftermath could word it better than me.


But in rifle scopes it doesn't matter at all. So effectively, you are correct.

You're right. Even head maff monkey makes a mistatement now and then.

the "true" distance is sin (angle) * distance. (BC in Alpine's Pic). (or DE--more on that in a minute)
Arc length is BE.

at small angles, sin (angle) is basically the angle itself and our scope measurements fit really really well into that approximation. (you can use tangent, its just a slightly different approx, but the reason to use sin is it makes the math easy

The forumula for sine is x - x^3/3! + x^5/5! so if x is small, its basically "x"

(and for the additionally pendatic among you for small x, cos x = 1 and tan = sin/cos or x/1 so you can see its pretty consistent around here whether you use sin or tan).

cos = 1 -x^2/2+x^4/4!

and for double double pendatic bonus points DE>BC because cosine < 1 when cosine is non-zero. So you can see whether you take BC or BD its really just a matter of which approximation you want to deal with.

 

[JAS-SH]

I am trying to find a trajectory correction formula for metric units and mrad. I have no problem finding a mrad formula where it butchers mrads with inches and yards.

Mrads and centimetres and meters

I'll make it simple for you.

.1 Mil at 100 yards is .36-inches and .36-inches is 9.14-mm. You can take it from there using and excel spreadsheet .....

 

[Aftermath]

Sort of, kinda. But it’s more like, as the angle increases then the difference becomes greater.
Regardless if it’s an inch or a mile. Ratios.

Correct.

You are much better at math than you give yourself credit for.

Those small town Idaho schools [where we all knew (and mostly still know) that school is your one chance to learn some stuff for free...no blood loss, no lost wages, no pushups...so you apply yourself] (or get your ass beat by mom and dad) do a real great job. In a couple more years you will be driving a truck, cutting trees, driving rail spikes, mixing chemicals to make paper or filling trays of primer cups with a volatile compound...just so you can buy a 6 pack of beer and a steak or some diapers and Gerber green beans.

 

[Holliday]

Switch to MOA…..

 

[Ronws]

Guys, guys! It's been staring us in the face all this time.

What we have here is a meading the great minds.

You are welcome, internet.

 

[The D]

Guys, guys! It's been staring us in the face all this time.

What we have here is a meading the great minds.

You are welcome, internet.

I will be meading this great mind in a little bit

 

[LeftyJason]

There is one benefit to this thread. The thread started in February which is mils/ moa month as decided in previous threads.

 

[JAS-SH]

The error in % is indeed independent of distance.
Here are the numbers:
View attachment 8623353 View attachment 8623354

That pretty chart shows 1-200 mil. That's misleading to me. I'm not using artillery, I'm using a rifle inside 1000 meters.

That equates to 0 Mil (actual) at 100 meters (E) and 9 Mil (actual) at 1000 (D). That's the reason we use .1 Mil. Sooo, The relevant range is inside your first two rows and so are the angles (1/2 degree elevation). I can't close my eyes and move the rifle up 1/2 degree and nail it.

 

[DocRDS]

Damn just found that I can't read the diagram. Apparently I've had too much mead!

 

[JAS-SH]

Switch to MOA…..
sa
View attachment 8623441

Same shit but with fractions. I like tenths (.1 Mil) - lot easier to work in my head. And the difference between Mil and MOA in scope clicks is smaller than the margin of error between the two measurements - 0.09825 inch. 4-scope clicks per MOA (1/4 MOA clicks) vs 10-scope clicks per Mil (.1 Mil)

All you need to know shooting Mil is one number .36. That is .36-inches per click at 100. The rest is sooo easy. Unless you cant remember one number .

 

[dustingaunder]

I hate having to go down range to measure the misses in inches and then walking all the way back to convert them to deciliters so I can adjust my mill scope to miss again but by less.

 

[Mike Casselton]

 

[alpine44]

That pretty chart shows 1-200 mil. That's misleading to me. I'm not using artillery, I'm using a rifle inside 1000 meters.

That equates to 0 Mil (actual) at 100 meters (E) and 9 Mil (actual) at 1000 (D). That's the reason we use .1 Mil. Sooo, The relevant range is inside your first two rows and so are the angles (1/2 degree elevation). I can't close my eyes and move the rifle up 1/2 degree and nail it.

I purposely took this to the extreme to show what DocRDS said :"And for the astute among you yes, the arc length is not the same as the vertical distance. But its like super super close (I think at 100y the difference is in the 4th decimal point)."

In other words, for typical rifle applications you can save yourself the effort of using trigonometric functions and just go with the arc length, which is simple multiplication of mils times distance as shown in previous posts.

OTOH, artillery folks HAVE to get a little fancier with the math.

 

[JAS-SH]

I purposely took this to the extreme to show what DocRDS said And for the astute among you yes, the arc length is not the same as the vertical distance. But its like super super close (I think at 100y the difference is in the 4th decimal point)."

In other words, for typical rifle applications you can save yourself the effort of using trigonometric functions and just go with the arc length, which is simple multiplication of mils times distance as shown in previous posts.

OTOH, artillery folks HAVE to get a little fancier with the math.

Lest we forget the Gremlins. The Gremlin leading the pack is called Dispersion. and there are many others whose purpose in life is to work feverishly on ruining your shot! Understanding math and geometry is very helpful, until the Gremlins show up, which they always do .

 

[6/250/40]

Doing my part, all day, keeps most of the Gremlins away...