Velocity Calculator

[nkbj]

Is there a calculator out there somewhere on the interseine for estimating black powder velocities?
I'd almost be surprised if there wasn't. Perhaps something that you could plug in powder charge, ball diameter, barrel length, whatever else...

My means of estimates has always been old handbooks and a chrono but thinking about it, seems someone would have put one together by now.

 

[Carbon 6]

Yes,
Are you looking for velocity or a ballistics computer ?
Velocity requires a chronograph. But you can find a computer here.

http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html

 

[Tom A Hawk]

http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html

 

[nkbj]

Fellas, those are exterior ballistics.

 

[Nameless Hunter]

I have never seen one, probably too many variables.
This is the closest I have found to your question:
http://www.namlhunt.com/traditionalmldata2.html

 

[Carbon 6]

What are you looking for then ?

 

[Zonie]

The way I read the OP, he is asking if there is a program that will give velocities based on black powder loads.

I doubt that such a program could be made. There are too many variables. The bore size and barrel length might be pretty easy to put into a program but then we have such things as, round ball or bullet? Bullet weight? What is the granulation of powder? What brand and type of powder? If it is for a patched roundball, exactly what is the ball and bore size and what thickness of cloth patch is being used? What kind of patch lubricant is being used?
Is the gun a percussion gun or a flintlock? If it is a flintlock, what size of vent hole does it have?

All of these things and more will have an effect on what velocity will be produced.

 

[SamTex1949]

What are you looking for then ?

Was sort of what I was wondering too !

 

[Sparkitoff]

I found this information on a 3X5 card in my notes. It is by no means a calculator, as it uses averages and gives ballpark figures. I supposed someone could put the numbers in Excel and the program would "calculate" the #'s for you basically by just doing the math. I would call this a reference more than a calculator. An old black powder gunsmith in NC gave this to me 30 years ago:

ALL PRB BASELINE 24-inch barrel
2F ADD 70 FPS per 10 grains above 1.5X caliber diameter. ADD 8.125 FPS per barrel inch up to 39-inches. From 40-inches up subtract 5.75 FPS for each barrel inch

3F ADD 78.25 FPS per 10 grains above 1.5X caliber diameter. ADD 8.85 FPS per barrel inch up to 39-inches. From 40-inches up subtract 5 FPS for each barrel inch

The first problem I see is that you need a starting velocity to be known.

Here is one of my own rifles: 54 caliber, 42-inch barrel

BOOK VALUE for 2F, 24-inch barrel at 80 grains is 1560 FPS
Using the 80 grain load (basically is 1.5X caliber) I add 8.125 (FPS Factor) X 15 (barrel length over 24, up to 39) and subtract 5.75 (FPS factor) X 2 (2 inches over 40 barrel length) Starting book velocity of 1560 FPS plus 110 FPS = 1670 FPS. So for ballistics calculations you would rely on 1670 FPS as your MV. I have a chronograph and I know factually that my MV average is 1654 FPS in this rifle, so the "formula" gives a result that is pretty close.

Here's another example of my .58 caliber, 26-inch barrel
Book value for 24-inch is 1419 FPS. This is 3F. Caliber 58 X 1.5 = 87 grains. I use 100 grains so I add 93 FPS to base of 1419 (13 grains over 87 base at 70 grains per 10). I add 8.85 FPS X 2 (2 inches of barrel over 24-inches). Equals 1529 FPS MV. My actual chronographed MV was 1534 FPS average. Again, pretty close.

I have no idea of the accuracy of this formula across the board, but it seems pretty reasonable for two of my rifles. I'm going to plug in others because now I'm curious. The biggest problem again is the baseline velocity with a 24-inch barrel. How do you figure that out? You have to chronograph a 24-in barrel in the caliber you are calculating or refer to a chart that provides 24-inch barrel data. The Hodgdon's chart for Pyrodex and Triple 7 does use 24-inch barrel data. There is not much for black powder or large calibers. You could take someone else's baseline data. For example, Herb has extensive chronograph data from a .58 caliber with a 24-inch barrel on this forum. Average his 2F or 3F velocities respectively and use it as a baseline. Someone with a Deer Slayer or Deer Hunter could chronograph a baseline load for you and you can calculate the rest to project it to your rifle. The "formula" does specify PRB too. I have no idea if it would apply to a conical or other projectile.

Have fun with it...

 

[Grenadier1758]

And after everything is done based on using information gathered in Zonie's post and you have gone to one of the Black powder loading manuals that has tables of velocity information for similar rifles, you, @nkbj, will still have to get out to the range and verify the expected results. I have seen too many virtually identical rifles that perform differently on the range. The differences in performance could be related to bore condition, patch thickness, lubricant, powder lot variance or one of many other differences in the loading process.

 

[Carbon 6]

Just buy a chronograph, then you know for sure what your velocities are.

 

[nkbj]

Thanks for the disadvice but the point of the question is as stated, whether or not someone had created a program yet for plugging in ball diameter, powder charge, barrel length and any other data points. Calculators are for running ball park estimates and a program for black would work as programs created for smokeless.

It's just something of interest to me so I asked if anyone knew of a calculator for black. Black really is fairly consistent and changing brand and gradation will usually create an extreme maximum change of less than ten percent.

Notice the linear relationship illustrated for each of these bullet weights, significantly less vertical fluctuation than one sees typically sees when loading cartridges with smokeless powders. I find black to be more forgiving and pleasingly predictable.


This is a data sheet from my percussion TC New Englander relined to use off the shelf .45 rifle molds. Even with a greater than 400 grain bullet the "curve" is still pretty darn flat.

For muzzleloaders I plot velocities to create tables. It's an easy means of figgerin' out where in the ball park you're gonna be when you load something.

 

[Nameless Hunter]

Thanks for the disadvice but the point of the question is as stated, whether or not someone had created a program yet for plugging in ball diameter, powder charge, barrel length and any other data points. Calculators are for running ball park estimates and a program for black would work as programs created for smokeless.

It's just something of interest to me so I asked if anyone knew of a calculator for black. Black really is fairly consistent and changing brand and gradation will usually create an extreme maximum change of less than ten percent.

Notice the linear relationship illustrated for each of these bullet weights, significantly less vertical fluctuation than one sees typically sees when loading cartridges with smokeless powders. I find black to be more forgiving and pleasingly predictable.


This is a data sheet from my percussion TC New Englander relined to use off the shelf .45 rifle molds. Even with a greater than 400 grain bullet the "curve" is still pretty darn flat.

For muzzleloaders I plot velocities to create tables. It's an easy means of figgerin' out where in the ball park you're gonna be when you load something.

Those are some good data points.
Given enough data points from various barrel lengths and powder charges, creating a spreadsheet calculator should be doable if all you're after is muzzle velocity. Mass of ball, barrel length, caliber, type of powder, grains of charge, etc. What's needed is real results from various rifles for adjusting the formula. If enough people reply with their chronograph verified muzzle velocities, I believe it could be done.

 

[PastorB]

Just buy a chronograph, then you know for sure what your velocities are.

Yup. So many variables, patch thickness, barrel length, ball size, cap manufacture (for percussion), etc. I've owned a chronograph for around 30 years, like the advertisement for Shooting Chrony said, "Buy yourself an eye-opener!". Most published data, especially T/C is "very optimistic", i have never achieved anything close to their velocities using the same guns and powder charges. I could go on, but here is something fairly typical that explains why a chrono is important if you want to know actual velocities. In my Pedersoli Frontier, caliber .54, 60 grains Goex fffg gives 1500 fps PRB, 75 grains gives almost nothing more, maybe 1550fps, but going up to 90 grains gives 1900 fps. This has been verified time and time again over different chrono's, and goes against all logic. Without a chrono I would guess or logically conclude I was getting 1750-1800 fps with the 75 grain load. Get a chrono, they are cheap ($100) compared to other stuff we use in our hobby.

 

[Carbon 6]

Is there a calculator out there somewhere on the interseine for estimating black powder velocities?

Thanks for the disadvice but the point of the question is as stated, whether or not someone had created a program yet for plugging in ball diameter, powder charge, barrel length and any other data points. Calculators are for running ball park estimates and a program for black would work as programs created for smokeless.

You are asking a computer to make a guess. The variables are literally a moving target.

Some of the variables could be standardized, but then you are right back to "ball park" book data. Or you could create a simulation, but even that's not real.

The fastest simplest way to calculate accurate velocity data is a chronograph.

The two most important pieces of information for any program would be velocity and ballistic coefficient. If you don't get velocity right everything will be off.

"Powder charge, and barrel length" are both factors that influence velocity.

Sorry I couldn't be more helpful.

 

[plmeek]

The OP is asking about internal ballistics of black powder and round projectiles.

This has actually been studied and mathematical relationships or models have been developed.

The first scientific investigation was conducted in the early 1700's by Benjamin Robins (1707 - 1751) and published in his "The New Principles Of Gunnery" in 1742. Robins approached the problem from a physics perspective using Newton's Laws.

A discussion of Benjamin Robins work can be found here Benjamin Robins on Ballistics. This link derives a general equation for velocity.

This link, Smooth Bore Cannon Ballistics, developed more specific equations. The equations are for cannon ballistics, but Robins tested them using a round ball of .75" diameter, so they still apply to small diameter guns. The coefficient may need to be adjusted to match modern powder energy.

The link above actually gives some JavaScript source code to do the calculations, though I would find it easier to do the calculations in Excel.

There is some other work I found some time back that approaches the problem from an empirical perspective. That work can be found at this link, Internal Ballistics of Muzzleloaders. This link is especially math heavy and will probably make most peoples' eyes glaze over and mind go numb, but the answer to the OP's question is embedded in this webpage by using his Equation 7 and the regression constants that best fit the gun the OP is working with.

The author has chosen to do his analysis and derive his equations for Muzzle Engery, but this can be converted to Muzzle Velocity with his Equation 5 and rearranging it to solve for velocity.

Either of these approaches will give you and estimate that may or may not be very accurate for any specific gun. As pointed out in other posts, there are a number of different variables that effect the velocity obtained from a gun and any equation or calculator will only give an "average" value. Actual measurements will likely vary to some degree from this "average".

 

[hanshi]

Can't say this will help, but I'll say it anyway. I've found many "tables" to range from poor to worthless. Of course a chronograph is the only way to get true velocity figures. The problem, I believe, is that velocity gains per charge increases aren't linear and can't be accurately predicted. An example is my .40 flintlock. A mere 5 grain increase from 35 grns to 40 grns yields 230 fps, or, 46 fps per grain of powder. Contrast that when going from 40 grains to 60 grains. In this case a 20 grain increase yields only around 200 fps, or, 10 fps per grain of powder. Change the lube, patch thickness, etc and these figures can easily flip-flop. I don't worry about velocity when developing a load; I want accuracy regardless of speed. After a load is developed I sometimes run shots over the chrony simply because I'm the curious sort.

Trajectories are best determined by firing rounds downrange. Although your findings may or may not agree with the tables, at least you'll know for sure that they are true and valid. Good luck.

 

[nkbj]

The OP is asking about internal ballistics of black powder and round projectiles.

This has actually been studied and mathematical relationships or models have been developed.

The first scientific investigation was conducted in the early 1700's by Benjamin Robins (1707 - 1751) and published in his "The New Principles Of Gunnery" in 1742. Robins approached the problem from a physics perspective using Newton's Laws.

A discussion of Benjamin Robins work can be found here Benjamin Robins on Ballistics. This link derives a general equation for velocity.

View attachment 53831
This link, Smooth Bore Cannon Ballistics, developed more specific equations. The equations are for cannon ballistics, but Robins tested them using a round ball of .75" diameter, so they still apply to small diameter guns. The coefficient may need to be adjusted to match modern powder energy.

View attachment 53833

The link above actually gives some JavaScript source code to do the calculations, though I would find it easier to do the calculations in Excel.

There is some other work I found some time back that approaches the problem from an empirical perspective. That work can be found at this link, Internal Ballistics of Muzzleloaders. This link is especially math heavy and will probably make most peoples' eyes glaze over and mind go numb, but the answer to the OP's question is embedded in this webpage by using his Equation 7 and the regression constants that best fit the gun the OP is working with.

The author has chosen to do his analysis and derive his equations for Muzzle Engery, but this can be converted to Muzzle Velocity with his Equation 5 and rearranging it to solve for velocity.

Either of these approaches will give you and estimate that may or may not be very accurate for any specific gun. As pointed out in other posts, there are a number of different variables that effect the velocity obtained from a gun and any equation or calculator will only give an "average" value. Actual measurements will likely vary to some degree from this "average".

Thank you sir. I'll check it out.

 

[borbal]

I think this is what the OP was looking for.

I just put this program together a few days ago and it needs some 'field testing', so I would appreciate it if you would feed in some numbers and see how it performs.

 

[Jim in Wisconsin]

An important factor in any calculation of muzzle velocity is going to be the energy output - power - whatever you want to call it - of the powder you are using. Different brands and batches of blackpowder will vary and that can't be put into the program because it won't be known. Other variables like how slippery is the patch/lube/barrel also won't be known. Those unknowns will make the outcome of the program into just a guess.
This could probably be done with modern smokeless powders and cartridge guns because those powders and bullets are real consistent.