Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
BEWARE, Problems with Exbal and G7 BC's
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="BryanLitz" data-source="post: 447915" data-attributes="member: 7848"><p>One more observation <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p>You might wonder why the outputs I gave above are different from the exbal value you got using 26.22", 10 degF, and 50% RH. Exbal got 439.9" of drop in these conditions, and the other programs got 428" of drop.</p><p></p><p>I believe the reason is because exbal assumes that you're giving it BC's that are corrected for the old Army Standard Metro (ASM) atmosphere. In fact, my BC's are corrected for the newer International Civil Aviation Organization (ICAO) atmosphere. My program, JBM, and Shooter all use the ICAO atmosphere.</p><p></p><p>In other words, my BC's are corrected for the ICAO atmosphere, and are only 'compatible' with programs that use the ICAO atmosphere.</p><p></p><p>The difference between a BC corrected to ASM vs ICAO atmosphere is about 1.8% (air density is .0751265 lb/ft^3 for ASM vs .0764742 lb/ft^3 for ICAO).</p><p></p><p>In other words, the effect of using my BC's in a 'non-compatible' program, is that the program applies the BC as if it were 1.8% lower than I intend them to be.</p><p></p><p>Reducing the G7 BC of 0.19 by 1.8% gives you .1866. Plugging this BC into an ICAO solver should produce the same output as an ASM program running with .19. I found that this BC produces a drop of 437", which is much closer to the exbal answer of 439.9".</p><p></p><p>I don't know for sure that exbal uses ASM, but I would bet that it does based on the above analysis.</p><p></p><p>One clue will be the default atmospheric inputs. When you turn on exbal from scratch, what does it populate the atmospheric fields like? If it has 29.53", 59 deg F, and 78% Hum, that's a good sign that it's using ASM because those are the ASM standard sea level conditions. The standard conditions for the ICAO atmosphere model are 29.92", 59 deg F, and 0% RH.</p><p></p><p>As one of my old engineering colleagues used to say to sum up a diagnosis: "It's either that... or something else"<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p></blockquote><p></p>
[QUOTE="BryanLitz, post: 447915, member: 7848"] One more observation :) You might wonder why the outputs I gave above are different from the exbal value you got using 26.22", 10 degF, and 50% RH. Exbal got 439.9" of drop in these conditions, and the other programs got 428" of drop. I believe the reason is because exbal assumes that you're giving it BC's that are corrected for the old Army Standard Metro (ASM) atmosphere. In fact, my BC's are corrected for the newer International Civil Aviation Organization (ICAO) atmosphere. My program, JBM, and Shooter all use the ICAO atmosphere. In other words, my BC's are corrected for the ICAO atmosphere, and are only 'compatible' with programs that use the ICAO atmosphere. The difference between a BC corrected to ASM vs ICAO atmosphere is about 1.8% (air density is .0751265 lb/ft^3 for ASM vs .0764742 lb/ft^3 for ICAO). In other words, the effect of using my BC's in a 'non-compatible' program, is that the program applies the BC as if it were 1.8% lower than I intend them to be. Reducing the G7 BC of 0.19 by 1.8% gives you .1866. Plugging this BC into an ICAO solver should produce the same output as an ASM program running with .19. I found that this BC produces a drop of 437", which is much closer to the exbal answer of 439.9". I don't know for sure that exbal uses ASM, but I would bet that it does based on the above analysis. One clue will be the default atmospheric inputs. When you turn on exbal from scratch, what does it populate the atmospheric fields like? If it has 29.53", 59 deg F, and 78% Hum, that's a good sign that it's using ASM because those are the ASM standard sea level conditions. The standard conditions for the ICAO atmosphere model are 29.92", 59 deg F, and 0% RH. As one of my old engineering colleagues used to say to sum up a diagnosis: "It's either that... or something else":) [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
BEWARE, Problems with Exbal and G7 BC's
Top