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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Drag Function question.
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<blockquote data-quote="Blaine Fields" data-source="post: 32259" data-attributes="member: 183"><p><BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> I guess I just don't see the point in adding another constant to do the same thing as the BC.</p><p> <HR></BLOCKQUOTE></p><p></p><p>Let's say that a shooter decides to use Berger bullets. The company publishes a single G1 BC for its bullets. How will the shooter devine the changes to BC necessary to obtain correct data? And what speed regimes will the shooter use? Well, he would have to spend quite a bit of range time to gather the data. Then, if he changed bullet manufacturer (other than Sierra), he'd have to go through the same arduous process. It seems to me that this approach defeats the entire rationale of having a "predictive" program.</p><p></p><p>Having a simple way to shape the drag curve is very practical. The shooter goes to the range and in one session determines the actual bullet drop at a sufficiently long distance where the bullet is close to transonic. Back at the computer, the shooter uses the single published BC value, the measured MV, ambient atmospheric variables and then matches the actual drop by the appropriate deceleration constant which mathematically shapes the drag curve to match what happens in reality.</p><p></p><p>In effect, this deceleration constant replicates what Sierra does by using multiple BCs to shape the drag curve, but the advantage is that this single deceleration constant is simple to derive from extremely limited range data.</p><p></p><p>[JBM - I think we just "highjacked this thread." Maybe we should begin a new thread to discuss the relative merits of the various methods to predict trajectory.]</p><p></p><p>[ 03-12-2004: Message edited by: Blaine Fields ]</p></blockquote><p></p>
[QUOTE="Blaine Fields, post: 32259, member: 183"] <BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> I guess I just don't see the point in adding another constant to do the same thing as the BC. <HR></BLOCKQUOTE> Let's say that a shooter decides to use Berger bullets. The company publishes a single G1 BC for its bullets. How will the shooter devine the changes to BC necessary to obtain correct data? And what speed regimes will the shooter use? Well, he would have to spend quite a bit of range time to gather the data. Then, if he changed bullet manufacturer (other than Sierra), he'd have to go through the same arduous process. It seems to me that this approach defeats the entire rationale of having a "predictive" program. Having a simple way to shape the drag curve is very practical. The shooter goes to the range and in one session determines the actual bullet drop at a sufficiently long distance where the bullet is close to transonic. Back at the computer, the shooter uses the single published BC value, the measured MV, ambient atmospheric variables and then matches the actual drop by the appropriate deceleration constant which mathematically shapes the drag curve to match what happens in reality. In effect, this deceleration constant replicates what Sierra does by using multiple BCs to shape the drag curve, but the advantage is that this single deceleration constant is simple to derive from extremely limited range data. [JBM - I think we just "highjacked this thread." Maybe we should begin a new thread to discuss the relative merits of the various methods to predict trajectory.] [ 03-12-2004: Message edited by: Blaine Fields ] [/QUOTE]
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Drag Function question.
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