Ballistics for Excel Forum

BfX => Member projects => Topic started by: mman on May 16, 2012, 05:25:41 PM

Title: Bfx ballistic calculator with 6-dof corrections
Post by: mman on May 16, 2012, 05:25:41 PM
I have used this calculator for a while now.. Feel free to download it and please let me know if you find any bugs. Includes following 6-dof corrections to vertical and horizontal deflections:

Spin drift (Litz)
Vertical and horizontal Coriolis (Litz)
Up/downhill shooting (Litz's improved riflemans rule)
Range wind drift (McCoy)
Aerodynamic jump aka crosswind vertical drift (Litz)
Wind weighting factors (McCoy)
Muzzle velocity temperature coefficient (linear inter/extrapolation)
Effect of atmospheric conditions to vertical zero range
Possibility to use horizontal zero to compensate spin drift for short ranges

I would say this is as accurate as it gets. Recommended for extra long ranges. I think there is no more external ballistic phenomena to correct. Or maybe effect of vertical wind component could be included? Calculator is pretty easy to use at the range when there is own sheet for every gun/load. Before shooting just "TARGET INFORMATION" and "ATMOSPHERIC CONDITIONS" values have to be changed. Everything else have to be set only for once. There is two default sheets: one for BC input and another for lapua bullets (radar drag data available).

You can download it from link below:
http://www.2shared.com/file/YEE1WaWl/Ballistic_calculator.html
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: admin on May 17, 2012, 08:16:10 AM
Mman, I have downloaded it, 't looks super.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: admin on May 18, 2012, 12:13:11 PM
Would it make sense to add your and Ians algorithms to BfX - awaiting the time that I have time and energy to a 6dof bfx?
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on May 18, 2012, 01:12:17 PM
I don't know exactly what you mean, but fine by me in any case. Equations in my sheet can be found from literature so they are free to use anyway. I think at least spin drift, aerodynamic jump and coriolis would be useful for some users...

By the way would it be lot of work to include inverse functions to Bfx? For example if BfX_D equals drop for the range of 100 m, inv(BfX_D) would equal range for 10 cm drop? I think some of us would find applications for this.

EDIT: I came across this today:
http://bulletin.accurateshooter.com/2012/05/new-ballistics-app-from-bryan-litz-for-android-devices/

Reticle aiming point calculation is a nice idea. I made my own for standard mildot reticle:
http://www.2shared.com/file/rZp3RuGk/Ballistic_calculator_with_mild.html
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: admin on May 19, 2012, 09:05:58 PM
By the way would it be lot of work to include inverse functions to Bfx? For example if BfX_D equals drop for the range of 100 m, inv(BfX_D) would equal range for 10 cm drop? I think some of us would find applications for this.

It is certainly possible, some times a bit tricky. Is bfx_i already not good enought to find the inverse:

Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on May 20, 2012, 09:59:25 AM
Thanks for the tip, I think bfx_i makes the trick.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: gvp on May 27, 2013, 03:28:09 PM
Includes following 6-dof corrections to vertical and horizontal deflections:

Spin drift (Litz)
Vertical and horizontal Coriolis (Litz)
Up/downhill shooting (Litz's improved riflemans rule)
Range wind drift (McCoy)
Aerodynamic jump aka crosswind vertical drift (Litz)
Wind weighting factors (McCoy)
Muzzle velocity temperature coefficient (linear inter/extrapolation)
Effect of atmospheric conditions to vertical zero range
Possibility to use horizontal zero to compensate spin drift for short ranges

fantastic job mman, thank you !!!

can you please explain me the "Effect of atmospheric conditions to vertical zero range" ... I think it's the "Constant zero" cell.
when I must set yes or no ?
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on May 27, 2013, 08:55:13 PM

fantastic job mman, thank you !!!

can you please explain me the "Effect of atmospheric conditions to vertical zero range" ... I think it's the "Constant zero" cell.
when I must set yes or no ?
Thanks! As it reads on comment: "If constant zero is chosen (value y) it is assumed that atmospheric conditions has no effect on vertical zero range." (with typos corrected :D)

Well, I guess this doesn't help you with choosing... You should choose "Yes" if you have seen at range that your zero does not change even when atmospheric conditions do. If we look at external ballistics your zero depends on temp, pressure, hum and muzzle vel but in practice this is not always the case. This is because internal ballistics can compensate the effect of external ballistics. It is actually very complicated topic and for gaining deeper understanding I recommend you to read this page:

http://www.varmintal.com/aflut.htm

In short vertical barrel vibration can change your zero on different conditions as well. But if you have no practical range results, probably better option is to choose "no" and then internal ballistics is excluded and your zero is not constant but depends on atmospheric conditions. Anyway if you zero your gun on short range this is not very critical but with long range zero it is. This is one of the reasons not to zero your gun much longer than 150 meters. Personally I use 130 meter zeros for centerfires and 50 m zeros for rimfires.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: gvp on May 27, 2013, 10:25:45 PM
thank you ...
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: gvp on May 30, 2013, 10:54:27 PM
a little correction to your 6dof workbook

in cell p11 you entered
=0,00007292*E16*T10*SIN(E19)*1000/H4

the correct is
=0,00007292*E16*T10*SIN(E19*pi()/180)*1000/H4
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on May 31, 2013, 03:17:35 PM
a little correction to your 6dof workbook

in cell p11 you entered
=0,00007292*E16*T10*SIN(E19)*1000/H4

the correct is
=0,00007292*E16*T10*SIN(E19*pi()/180)*1000/H4

Yeah you are right. Thanks! It happens to be that on my latitude the difference is very small so I haven't noticed the error.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: gvp on June 05, 2013, 10:14:16 PM
mman, just a confirmation if the following terms-effects are the same ...

Crosswind drift = Aerodynamic jump = Magnus effect ?
Coriolis @vertical axis = Eotvos effect = vertical component of Coriolis force ?
Coriolis @horizontal axis = horizontal component of Coriolis force ?
Spin drift = Gyroscopic drift ?

thanks ...
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on June 06, 2013, 07:23:32 PM


Crosswind drift = Aerodynamic jump = Magnus effect ? No

Crosswind vertical drift = Aerodynamic jump on my 6-DOF calculator but aerodynamic jump is actually more general phenomena which causes drift when projectile's orientation changes against oncoming airflow. Aerodynamic jump is a result of lift force which is actual aerodynamic force. Also spin drift is a cause of lift force. Magnus effect is a result of actual magnus force but this is usually neglected at bullet trajectories because it is so small.

Coriolis @vertical axis = Eotvos effect = vertical component of Coriolis force ? CONFIRMED
Coriolis @horizontal axis = horizontal component of Coriolis force ? CONFIRMED
Spin drift = Gyroscopic drift ? CONFIRMED
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on November 26, 2013, 07:01:10 AM
Mman, more a request than anything else!

I've been playing with the SS and it's a great work, but I wonder if you can update it to make ready to Firing Tables

I mean, some kind of grid, with Range, Path and Wind Drift, say from 0 to 2000

Anything like that will be very useful.

Thanks for your time in advance.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on November 30, 2013, 05:00:02 PM
375CT is there a reason why?

Internet is full of good table-kind ballistic calculators. One of them is jbm ballistics. This one is designed for shooting range use only. On situation where you need to know corrections for one distance. It would make sense to create all new sheet for data tables. It should be pretty easy to do by yourself... Let me know if you need help with it.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on November 30, 2013, 09:12:29 PM
375CT is there a reason why?

Internet is full of good table-kind ballistic calculators. One of them is jbm ballistics. This one is designed for shooting range use only. On situation where you need to know corrections for one distance. It would make sense to create all new sheet for data tables. It should be pretty easy to do by yourself... Let me know if you need help with it.

Mman, the only reason is to make it more field use friendly, meaning ready to produce tables.

But of course, it's just a request, if you don't find it of your interest, fine by me. Will use it "as is"

Honestly I'm not that skilled when it comes to Excel, and even been trying several times, no way. :(

My world is VB.Net programming.

Unforunately I cannot translate some of the words in finnish (the ones that are white on white)

Again, great work!
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on November 30, 2013, 09:51:26 PM

Mman, the only reason is to make it more field use friendly, meaning ready to produce tables.

But of course, it's just a request, if you don't find it of your interest, fine by me. Will use it "as is"

Honestly I'm not that skilled when it comes to Excel, and even been trying several times, no way. :(

My world is VB.Net programming.

Unforunately I cannot translate some of the words in finnish (the ones that are white on white)

Again, great work!

Okay, I'll try to find time for it...

Just for interest what's your application? Are you long range shooter? These 6-dof corrections I have added are not usually very important for short (normal) shooting ranges.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 01, 2013, 08:16:33 PM

Okay, I'll try to find time for it...

Just for interest what's your application? Are you long range shooter? These 6-dof corrections I have added are not usually very important for short (normal) shooting ranges.

Mman, thanks for your kind reply. If you just find the time, great!

My main interest is Long Range (up to 2000m), and any tool that helps me to investigate it, the better. I think Robert did a great job by putting together his BfX software.

But like I said, Excel while undoubtedly a good tool for this job, is not where I find myself most comfortable.

How is computed your Vertical Drift? It's as a result of Aerodynamic Jump as detailed by Litz?
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 01, 2013, 09:12:26 PM
For those ranges it really makes sense to use 6-DOF corrections. If you need to get first round hits lapua's radar data is probably the most accurate way to calculate trajectories. Some Finnish snipers say .338 250 gr. lock base FMJ bullet should stay stable trough transonic velocities. I don't have personal experience however because I don't shoot past supersonic (always less than 1500 m). But if I were to shoot that far I would try that bullet (with 338 LM cartridge ) first because there is radar data available for it as well. You can also download Quick load unlimited for computer and viking ballistics for mobile phone. Both of them include radar data for lapua bullets.

http://www.lapua.com/en/customer-center/lapua-ballistics/lapua-ballistics-software.html

How is computed your Vertical Drift? It's as a result of Aerodynamic Jump as detailed by Litz?
If you mean vertical drift due to crosswind that's a yes. See my first post on this thread.

See also attached excel sheet. Hope that's what you meant.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 01, 2013, 10:29:55 PM
For those ranges it really makes sense to use 6-DOF corrections. If you need to get first round hits lapua's radar data is probably the most accurate way to calculate trajectories. Some Finnish snipers say .338 250 gr. lock base FMJ bullet should stay stable trough transonic velocities. I don't have personal experience however because I don't shoot past supersonic (always less than 1500 m). But if I were to shoot that far I would try that bullet (with 338 LM cartridge ) first because there is radar data available for it as well. You can also download Quick load unlimited for computer and viking ballistics for mobile phone. Both of them include radar data for lapua bullets.

http://www.lapua.com/en/customer-center/lapua-ballistics/lapua-ballistics-software.html

How is computed your Vertical Drift? It's as a result of Aerodynamic Jump as detailed by Litz?
If you mean vertical drift due to crosswind that's a yes. See my first post on this thread.

See also attached excel sheet. Hope that's what you meant.

Mman, thanks a lot for the new spreadsheet, it's exactl what I was after, now it's a really useful format. ;D

Please, could you explain what is "Effect of atmospheric conditions to vertical zero range" ?

Again, thanks for your time, it's much appreciated.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 02, 2013, 05:25:45 AM
No problem. And regarding to your question, please take your time and read this thread through first. Gvp asked this one before.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 02, 2013, 06:42:14 PM
No problem. And regarding to your question, please take your time and read this thread through first. Gvp asked this one before.

Thanks.

You wrote :

Coriolis @vertical axis = Eotvos effect = vertical component of Coriolis force ? CONFIRMED

As far as I can tell, it's incorrect to call Coriolis Vertical as Eötvös. They "look" similar, but they are different animals.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 02, 2013, 07:32:05 PM
It's says so in Litz's book but there is other errors as well. Now you have opportunity to correct us.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 02, 2013, 08:29:36 PM
It's says so in Litz's book but there is other errors as well. Now you have opportunity to correct us.

Well, Litz book is not short on several errors, as you rightly pointed out. :)

And that includes, his poor understanding of Dr. Pejsa's work. I discussed this wih him in the past, and in my opinion, he never understood what Pejsa is all about. He also cites wrongly McCoy on several subjects, for instance on Coriolis.

There are several papers on this subject where this is explained in full detail, and it's clear that some programs like FFS (Lex Talus) also make the same error. Maybe they are looking to impress somebody. But, they are different things, no matter what.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 02, 2013, 08:43:41 PM
Still waiting for the education part  :).. I'm eager to learn something new  ;D.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 02, 2013, 09:37:43 PM
Still waiting for the education part  :).. I'm eager to learn something new  ;D.

http://www.cleonis.nl/physics/phys256/eotvos.php (http://www.cleonis.nl/physics/phys256/eotvos.php)

just to start, and you can check McCoy on Coriolis too.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 02, 2013, 09:47:15 PM
Picture from your link:
(http://i.imgur.com/MtuH3mL.jpg)

For me it still looks like a vertical component of coriolis. What am I missing?
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 02, 2013, 10:04:24 PM
Check the paper by Persson, page 5

http://www.aos.princeton.edu/WWWPUBLIC/gkv/history/persson_on_coriolis05.pdf (http://www.aos.princeton.edu/WWWPUBLIC/gkv/history/persson_on_coriolis05.pdf)
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 02, 2013, 10:53:35 PM
Seems like you are right. However I didn't find anything about this from McCoy.

I have to study if it is worth adding this centrifugal effect on my ballistic calculator.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 02, 2013, 11:20:37 PM
Seems like you are right. However I didn't find anything about this from McCoy.

I have to study if it is worth adding this centrifugal effect on my ballistic calculator.

In my humble opinion, it's not worth the effort, but I have to admit, adding it will make for a more complete solution and I cannot see ill effects at all. So, why not?  :D

You are right, McCoy never mentioned it, I just poined out to him for the reference on Coriolis from a ballistics perspective.

By the way, Coriolis as detailed by Litz is also wrong.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 03, 2013, 11:53:58 AM
Okay after thinking this a while I think there is no reason to add anything on my calcuculator. It turns out you and Litz are both correct, in a way. In genaral you are right:

Eötvös = vertical coriolis + centrifugal acceleration

However in case of small arms shooting cetrifugal acceleration is zero and furthermore in this special application

Eötvös = vertical coriolis

So basicly Litz got this right. I think this is also the reason why McCoy didn't mention cetrifugal acceleration in his book.

(http://i.imgur.com/vlRFgdI.jpg)

See the picture with exxaggerated dimensions. When shooting with the rifle you can actually see the target. It means that line of sight is the reference line for ballistic corrections and this centrifugal acceleration is automatically compensated. In the picture angle A is the scope correction value (taken from ballistic calculations).

However in the case of artillery fire horizontal level is the reference from which corrections are calculated. Then this centrifucal acceleleration is not automatically compensated but has to be taken into account in ballistic calculations.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 03, 2013, 07:02:11 PM
Sorry if I wasn¡t clear enough. Litz is wrong in the way he describes the equations to compute Coriolis. It's a bad interpretation of how McCoy addressed it.

I concur with your analysis, but my original point was, that technically speaking, Eötvös is not the Coriolis vertical deflection, because it's not.

A very different thing is not to consider its effects as you pointed out.

By the way, nice picture! Hope I have your skills with technical drawings! :)
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 03, 2013, 08:01:42 PM
We have to remember that Litz's book is meant for average shooter to present ballistics as simple as possible. It's not technical book like McCoy's is.
However this was useful exercise for me. Lesson learned. Thanks for bringing this up.

See "Hit probability" thread about one fundamental error in Litz's book. It's quite big one for a guy who wrote whole another book about hit probability...
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 03, 2013, 10:51:03 PM
We have to remember that Litz's book is meant for average shooter to present ballistics as simple as possible. It's not technical book like McCoy's is.
However this was useful exercise for me. Lesson learned. Thanks for bringing this up.

See "Hit probability" thread about one fundamental error in Litz's book. It's quite big one for a guy who wrote whole another book about hit probability...

Any chance to make your spreadsheet available again? I tried the dropbox and is dead... :(
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: mman on December 04, 2013, 07:45:33 AM
Latest version is in Finnish but I can share the old one.
Title: Re: Bfx ballistic calculator with 6-dof corrections
Post by: 375CT on December 04, 2013, 04:07:09 PM
Latest version is in Finnish but I can share the old one.

If there is not much finnish, no problem I can use a translator. Anyway, the old one is always welcomed ;)