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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Ballistic Program Inconsistencies
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<blockquote data-quote="BryanLitz" data-source="post: 310966" data-attributes="member: 7848"><p>Kyle,</p><p>There are many reasons why programs can give <em>slightly</em> different answers, but few reasons why they may give drastically different answers.</p><p></p><p>Here's a list of some things that come to mind:</p><p>Solution method. Certain simplifications of the math are made in some solution methods to get to an answer. The Siacci and Pejsa solutions are examples of solution methods that use 'short-cuts' to get to an answer. These short cuts are usually not very costly in terms of accuracy. The Pejsa solution doesn't interpret BC the way other programs do. Solutions that use numerical integration (point mass solutions) will compromise the least accuracy.</p><p></p><p>Atmosphere. There are two definitions of the 'standard' atmosphere in common use: Army Standard Metro (ASM) and ICAO (something like: International Civil Aviation Administration). Some programs use one, some the other. BC's are also defined by one or the other. One possible error is to use a BC that's defined based on ASM in a program that uses ICAO or vise versa. This will introduce an effective error of 1.7% in the BC (or air density) that you're using.</p><p></p><p>Of course there is user error to consider. If the inputs are misleading or unclear, one could accidentally enter inconsistent information.</p><p></p><p>My advice is to check whatever program you use against the JBM online ballistics program. JBM uses a point mass solver, and is extremely accurate. You can tell how accurate your program is by seeing how well it compares to JBM.</p><p></p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 310966, member: 7848"] Kyle, There are many reasons why programs can give [i]slightly[/i] different answers, but few reasons why they may give drastically different answers. Here's a list of some things that come to mind: Solution method. Certain simplifications of the math are made in some solution methods to get to an answer. The Siacci and Pejsa solutions are examples of solution methods that use 'short-cuts' to get to an answer. These short cuts are usually not very costly in terms of accuracy. The Pejsa solution doesn't interpret BC the way other programs do. Solutions that use numerical integration (point mass solutions) will compromise the least accuracy. Atmosphere. There are two definitions of the 'standard' atmosphere in common use: Army Standard Metro (ASM) and ICAO (something like: International Civil Aviation Administration). Some programs use one, some the other. BC's are also defined by one or the other. One possible error is to use a BC that's defined based on ASM in a program that uses ICAO or vise versa. This will introduce an effective error of 1.7% in the BC (or air density) that you're using. Of course there is user error to consider. If the inputs are misleading or unclear, one could accidentally enter inconsistent information. My advice is to check whatever program you use against the JBM online ballistics program. JBM uses a point mass solver, and is extremely accurate. You can tell how accurate your program is by seeing how well it compares to JBM. -Bryan [/QUOTE]
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Ballistic Program Inconsistencies
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