Lock'nLoad a Ballistic Program for Cannons and Mortars

[Parrott-Cannon]

The attached zip file contains a ballistic program (Lock'nLoad) for black powder cannons and mortars.  I have spend the better part of this year writting code and gathering daya on my own cannons and mortar to assure the accuracy of Lock'nLoad.  Please provided constructive feed back.  I am currently working on a internal ballistic module for Lock'nLoad and a flat fire trajectory module.

Enjoy!

[Double D]

Looks interesting. But some questions.

Where do I get velocity? 

Is there a function to plug in time of flight, distance, angle and projectile info to get velocity?

[GGaskill]

I got a couple of error messages after reviewing all the trajectories.  The second one took the program down.

[Parrott-Cannon]

Looks interesting. But some questions.

Where do I get velocity? 

Is there a function to plug in time of flight, distance, angle and projectile info to get velocity?

Look at the examples to get a feel for velocity.

3 variables and one function define the trajectory - They are:

Velocity
Ballistics Coefficient
Barrel Elevation
Drag Function - 5 are selectable in the program.

You can calculate any one of the variables if the other two are known against a specific drag function.

Velocity and Barrel Elevation are easy to measure.  The Ballistic Coefficient and Drag functions are expensive to measure.  Velocity can be measured in a number of ways:

Chronograph http://www.shootingchrony.com/ about 100 dollars
High Speed Photograph - expensive about 1200 dollars
By sound - http://arxiv.org/ftp/physics/papers/0601/0601102.pdf - very inexpensive
Doppler Radar - Radar guns are cheap but do not measure velocities at cannon velocities - high end systems like the military use provided velocity, BC, and drag function information no comment on their cost.

Time of Flight and range will give an average velocity for the trajectory.  A modul can be written for muzzle velocity - no big deal - but you still have to know the BC and select a drag function that describes the projectial's air resistance.

This question regarding velocity is why I am interested in developing an internal ballistics model for cannons and mortars.

An approximate equation for muzzle velocity for ball with a diameter of 1.68" is:

       Muzzle Velocity = 2.0258 X grains of powder  + 8.2488   -  the equation is valid for fg, ffg, and Cannon grade poeders.

Hope this helps.

[Parrott-Cannon]

I got a couple of error messages after reviewing all the trajectories.  The second one took the program down.

Thank you for the information

The program was developed in a windows XT environment.  What version of Wndows are you using?  I tried the program on my wifes computer and had the same results.  for the momment if you want to look at the complete sey of trajectory graphs closing them individually did not cause a crash on my wifes computer.  I know how to fix the problem and will provided an updated file within a few days.

[Double D]

Look at the examples to get a feel for velocity.

3 variables and one function define the trajectory - They are:

Velocity
Ballistics Coefficient
Barrel Elevation
Drag Function - 5 are selectable in the program.

You can calculate any one of the variables if the other two are known against a specific drag function.

Velocity and Barrel Elevation are easy to measure.  The Ballistic Coefficient and Drag functions are expensive to measure.  Velocity can be measured in a number of ways:

Chronograph http://www.shootingchrony.com/ about 100 dollars
High Speed Photograph - expensive about 1200 dollars
By sound - http://arxiv.org/ftp/physics/papers/0601/0601102.pdf - very inexpensive
Doppler Radar - Radar guns are cheap but do not measure velocities at cannon velocities - high end systems like the military use provided velocity, BC, and drag function information no comment on their cost.

Time of Flight and range will give an average velocity for the trajectory.  A modul can be written for muzzle velocity - no big deal - but you still have to know the BC and select a drag function that describes the projectial's air resistance.

This question regarding velocity is why I am interested in developing an internal ballistics model for cannons and mortars.

An approximate equation for muzzle velocity for ball with a diameter of 1.68" is:

       Muzzle Velocity = 2.0258 X grains of powder  + 8.2488   -  the equation is valid for fg, ffg, and Cannon grade poeders.

Hope this helps.

The program also crashed a lot for me also, using Vista.

How do I select a projectile from you library.

I will send you one of my golf ball mortars and one steel ball and one one golf ball. 

Using the methods suggested above you measure the velocity of the two projectiles.

I have a chronograph  Oehler 35 and I would wouldn't put my sky screens in from of my golf ball mortars in from of i

I like the idea of your program, but I think you are making it to complex for our purposes.  Apply the K.I.S.S. formula.

Provide a library of projectiles to select from with precalculate BC's and drag functions.

We can live with average  velocities.

Since you model predicts velocities with a given charge of powder how about a module that lets plug in the powder charge and gives a predicted velocity.

Once I had your predicted velocity numbers from the powder/velocity equation and put that in your program the results I got compared with the results I get on the range..

My 30 yard charge for a golf ball is 24 grains.  Your program predicted 94 feet.

I think your little program has some real potential for our use, so keep on working on it

I would like to see it it work in reverse.

I am shooting a golf ball at a target 100 yards away, how much powder do i need. 

[GGaskill]

What version of Windows are you using?

XP Home 2002 SP3

[dougrunnels]

I h times.ave thought about measuring my BB mortar many times.  It would be interesting to know what speed the ball is traveling.  I have a Chrony and might be  interested in trying to measure a BB.  Except I am unsure how to set it up.  The "window" would have to be increased to accept the BB.  With such a large projectile, would the screens be necessary?  What distance should I set it from the muzzle?  Any ideas?  Suggestions?  Has anyone done this before?  With the FPS, and the angle and the weight of the projectile....?  Interesting.

[Cat Whisperer]

The attached zip file contains a ballistic program (Lock'nLoad) for black powder cannons and mortars.  I have spend the better part of this year writting code and gathering daya on my own cannons and mortar to assure the accuracy of Lock'nLoad.  Please provided constructive feed back.  I am currently working on a internal ballistic module for Lock'nLoad and a flat fire trajectory module.
Enjoy!

Cool program.  I'm impressed with the number of the real-life variables that  you've included. (Haven't had to include those since I was at Ft Sill.) 

We had the GFT's (graphical firing tables) and a few other items to calculate how far the bullets would go.  Each round and type of cannon and type of powder had it's own GFT.  Also had to crank in rotation of the earth and clearances above ridges and such. 

Not an easy task.

[GGaskill]

I think the easiest way to get an order of magnitude estimate of muzzle velocity is to take a movie of a firing with a yardstick (or a custom two yard stick made from a 6' piece of 1x4) near the muzzle and watch how much the shot moves between adjacent frames.  You do have to know the frame rate of the camera. You don't need a high frame rate for this.

[dan610324]

most cameras just takes 30 pictures per second
if you doubble the sugested length and paint it black and white , one foot black and the next white and so on you will have a fair chans to be able to calculate the velocity very good up to 360 feet per second  IF you got a photo directly when the bb leaves the muzzle .
so for mortars it maybe is enough , I dont know how low the velocity is
but the idea is very good 

[Double D]

But since the these mortars only shot 50-60 fps...

[Parrott-Cannon]

Thank all who have provided feed back.   First,  I am sorry about the program crashing.    I have corrected the problem and tested it on several different computers with no problems.  This version 1.01 should be available by the end of the week (sounds like Microsoft).

The new version will have four additional capabilities:

Estimation BC from weight and sectional density of your projectile
Estimation of Muzzle Velocity form type of powder, projectile physical properties and the configuration of the barrel.
Calculation of the Muzzle Velocity from a known range, BC, and drag function
 Amount of powder to hit a target – for mortars

The accuracy of the program is very good as illustrated in the following table for a Napoleon Cannon

Angle         Range (ft)*      Program Cal Range(ft)   Percentage Error

1         1860            1711            8.0         

2         2625            2814            7.2

3         3600            3671            2         

4         4366            4397            0.71      

3         5040            5040            0

this data came from the Confederate Artillery Manual

When I analyzed the data statically it was obvious that a Confederate Artillery Range data is a linear extrapolation of data at measured at two ranges.

If you have data on muzzle velocities, types of projectiles, or ranges please provide – also include a description mortar or cannon used.  All my cannons and mortars I purchased from Dom they include:

GB Mortar older version 1.72 bore and ¾ by 1 inch powder chamber
TB Mortar older version 2.65 bore and 1 by 1 inch powder chamber

French 75 1.72 bore, no powder chamber, 26” bore  depth
Parrott  1.72 bore, no powder chamber, 24” bore depth
Howitzer 2.63 bore, powder chamber 1.25 x 3 inches , bore depth 19.25

[Double D]

Where do I get the Sd of  1.68 diameter steel ball?

[dan610324]

are they as slow as 50-60 fps ??
I thought they should be around 200 fps
thats what I love with this place , there is so much to learn

[Double D]

Actually Dan I don't know how slow they really are. But everything cross checks.  Using this program and the parameters available with in it, in order to make a golf ball go 90 feet, I have to plug in a velocity of 55.3 fps.

To cross check, I used the approximation equation provided:

Approximate equation for muzzle velocity for ball with a diameter of 1.68" is:

       Muzzle Velocity = 2.0258 X grains of powder  + 8.2488

55.3 - 8.2488 =    47.0512

47.0512/2.0258 = 23.226 grains.

For 30 yards I use 24 grains of black powder in my golf ball mortar.

[Cat Whisperer]

Does not the Ballistic Coefficient vary a bit with velocity.  (Some tables/charts for bullets list two different BC's one for higher and one for lower velocities.)

There has to be a formula somewhere! 

[Parrott-Cannon]

I use a high speed camera to measure velocities.  It can handle velocities upto 1200 fps.  An has a fame rate of 1200 frames per second.  I have estimated  ballistic coefficient of a 1.68 inch steel ball as 1.19 with the current version of my BC calculator.  I used 700 for the velocity.

[Parrott-Cannon]

I use a high speed camera to measure velocities.  It can handle velocities upto 1200 fps.  An has a fame rate of 1200 frames per second.  I have estimated  ballistic coefficient of a 1.68 inch steel ball as 1.19 with the current version of my BC calculator.  I used 700 for the velocity.

And the Ball>=0.75 drag function

[Double D]

When I tried to compute ballistic coefficient for a golf ball at 30 yards, the shortest distance available was 217.  217 what?

Don't think we are putting you down by pointing out these issue, on the contrary we are your beta testers, and we are providing you feed back.  I like the basic premise that you are working on.  I have several freeware and payware ballistics programs and none of them work for cannons or mortars.

[Cat Whisperer]

Where do I get the Sd of  1.68 diameter steel ball?

Recognizing that the question was intended to be feedback to the program (having the SD and BC calculators would be interesting in the program), there is a interesting list of definitions and formulas in Wikipedia ( http://en.wikipedia.org/wiki/Ballistic_coefficient ) for what that's worth.

[Parrott-Cannon]

Does not the Ballistic Coefficient vary a bit with velocity.  (Some tables/charts for bullets list two different BC's one for higher and one for lower velocities.)

There has to be a formula somewhere! 

Yes the BC changes with velocity especially is and pass the trans-sonic speeds.  For velocities below the speed of sound the change is very small.  The BC also changes with Barrel Elevation but again the changes is small.

[Parrott-Cannon]

When I tried to compute ballistic coefficient for a golf ball at 30 yards, the shortest distance available was 217.  217 what?

Don't think we are putting you down by pointing out these issue, on the contrary we are your beta testers, and we are providing you feed back.  I like the basic premise that you are working on.  I have several freeware and payware ballistics programs and none of them work for cannons or mortars.

I am happy for the feedback.  When you work on something everyting is obvious.  I chose feet because it reduces error at the velocities we experience with our mortars and cannons.

When you run the Ballistic Coefficient by Range routine it calculates a lower and upper range in feet based on the Velocity, Barrel Elevation and Drag function specified under "Load".  24 grains is a muzzle velocity of about 88 fps - so at 90 feet with a barrel elevation of 75 degrees the BC=0.0533.

All ranges are in feet in the program.

[Cat Whisperer]

I ran into that too.  Putting the units by every place data is to be entered would be good.

[GGaskill]

Where do I get the Sd of  1.68 diameter steel ball?

From Wikipedia:  "SD = sectional density, SD = mass of bullet in pounds or kilograms divided by its caliber squared in inches or meters; units are lb/in² or kg/m²."

Calculate it.  For a Fox "golf ball," the weight is 325 grams and the diameter is 42.67 mm, so the Sd would be .325/.04267² = 178.5; in English units, the numbers would be .7159 lbs / 1.68" x 1.68" = .2536; I cross-checked the English units formula against the Sd's posted for some Sierra bullets and they use the same formula. The ratio between kg/m² and lb/in² is 2.2 lbs/kg / (39.37 in / m)² which equals .00142, so 178.5 x .00142 = .2533 which is the same within rounding errors.

Presumably, the .2536 should be used in the Ballistics Calculator.

[Double D]

That will teach me to demonstrate my 6th grade math skills!

[GGaskill]

Regarding velocity from video, I have watched video of my bowling ball mortar and estimated the velocity at around 100 ft/sec.

[Cat Whisperer]

That will teach me to demonstrate my 6th grade math skills!

YUP.  (For some of us, it's about time too.)   

[Parrott-Cannon]

The wife said work in the yard - so I have been working in the yard and doing honey do thing for serveral days.  I am about to get caught up so back to programing latter today.

The best way to determine the BC is to calculate the value based on experimental data (velocity, range).

The drag functions are the Cd.  The ballistic coefficient (BC) is used to modify the Cd for different projectials with the same basic "shape" to estimate the drag.  Plot the drag functions - look at the difference between the >0.75 inch ball and the <=0.75 inch ball.  Their is not a simple BC that will convert these two drag functions that is why the two drag functions are included.  For balls in either drag function catigory their is a why to estimate the BC.  The new version of the software will provide an estimate of BC for different size balls within same drag function.  The best way to determine the BC is to calculate the value based on experimental data.


BC=Weight of the projectile in pounds/(Form Factor X projectile Diameter X projectial Diameter)

What is the Form Factor (i):  Good question - i=Cd unknown projectile / Cd of reference projectile. 

Hope this helps :

Back to work

[Double D]

Yes in one of the other threads we discussed the ramifiacations of crossing SWMBO...get the yard work done.