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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Wind and it's affects?
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<blockquote data-quote="Mikecr" data-source="post: 417792" data-attributes="member: 1521"><p>I'll describe the 10 columns, to hopefully answer your questions.</p><p></p><p>- COLUMNs 1-3 are are part of a baseline solution provided by a Pejsa spreadsheet from input parameters to the far left(MV3000, BC.500, etc)</p><p></p><p>- COLUMNs 4 put my mind in a ditch initially. I needed a representative velocity throughout each 50yd increment to determine incremental LAG.</p><p>The velocity shown to drop to 2901fps by 50yds in COLUMN2, does not represent what velocity was through the first 50yds, but only what it ended up at.</p><p>'Effective velocity' was somewhere between 3000-2901 for that 50yds, and yet was not simply the halfway point(non-linear change). </p><p>So I started with a simple avg, and added again a percentage of the average, to the average, to roughly balance the checkbook(*I'll followup on this at COLUMN 10). </p><p>You noticed 15fps diff early, but actually it gradually ends up 13fps diff downrange. That's because averages spread downrange(slower loss rate).</p><p>With this I'm confident that the velocities in COLUMN4 represent the effective velocities well enough for each -50yd increment -for these velocities -& BC. </p><p></p><p>- COLUMN 5 shows the incremental velocity drop w/resp to original MV(VacVelDelta).</p><p>- COLUMN 6 just shows COLUMN5 as percentages.</p><p></p><p>- COLUMN 7 shows incremental T-LAG based on the ROW6 percentage of time added(inverse of dropping vacuum velocity)</p><p></p><p>- COLUMN 8 shows incremental path deviations caused by a 10mph crosswind. This is WIND*T-LAG at each 50yd increment(not summing)</p><p></p><p>- COLUMN 9 converts COLUMN8 deviations per 50yd to MOA</p><p></p><p>- COLUMN 10 brings it all together. Each row shows the individual 1kyd drift contribution, of a 10mph crosswind, produced at each range increment.</p><p>The bottom cell sums the contributions for total drift at 1kyd. </p><p>*The correction applied to effective incremental velocities in COLUMN 4, allowed COLUMN10 TOTAL to match the original solution.</p><p>It's not dead nutz, could use a bit of exponential, but provides for overall accuracy.</p><p>So please don't take this too literal. It's merely an effort towards general understanding of the impacts of near to far winds.</p><p></p><p>Phorwath</p><p>The ~1.5moa at 1kyd = COLUMN10 50yd + 100yd deviations</p><p>The ~1.5moa at 1kyd -value printing at 100yds = COLUMN8 50yd + 100yd deviations</p></blockquote><p></p>
[QUOTE="Mikecr, post: 417792, member: 1521"] I'll describe the 10 columns, to hopefully answer your questions. - COLUMNs 1-3 are are part of a baseline solution provided by a Pejsa spreadsheet from input parameters to the far left(MV3000, BC.500, etc) - COLUMNs 4 put my mind in a ditch initially. I needed a representative velocity throughout each 50yd increment to determine incremental LAG. The velocity shown to drop to 2901fps by 50yds in COLUMN2, does not represent what velocity was through the first 50yds, but only what it ended up at. 'Effective velocity' was somewhere between 3000-2901 for that 50yds, and yet was not simply the halfway point(non-linear change). So I started with a simple avg, and added again a percentage of the average, to the average, to roughly balance the checkbook(*I'll followup on this at COLUMN 10). You noticed 15fps diff early, but actually it gradually ends up 13fps diff downrange. That's because averages spread downrange(slower loss rate). With this I'm confident that the velocities in COLUMN4 represent the effective velocities well enough for each -50yd increment -for these velocities -& BC. - COLUMN 5 shows the incremental velocity drop w/resp to original MV(VacVelDelta). - COLUMN 6 just shows COLUMN5 as percentages. - COLUMN 7 shows incremental T-LAG based on the ROW6 percentage of time added(inverse of dropping vacuum velocity) - COLUMN 8 shows incremental path deviations caused by a 10mph crosswind. This is WIND*T-LAG at each 50yd increment(not summing) - COLUMN 9 converts COLUMN8 deviations per 50yd to MOA - COLUMN 10 brings it all together. Each row shows the individual 1kyd drift contribution, of a 10mph crosswind, produced at each range increment. The bottom cell sums the contributions for total drift at 1kyd. *The correction applied to effective incremental velocities in COLUMN 4, allowed COLUMN10 TOTAL to match the original solution. It's not dead nutz, could use a bit of exponential, but provides for overall accuracy. So please don't take this too literal. It's merely an effort towards general understanding of the impacts of near to far winds. Phorwath The ~1.5moa at 1kyd = COLUMN10 50yd + 100yd deviations The ~1.5moa at 1kyd -value printing at 100yds = COLUMN8 50yd + 100yd deviations [/QUOTE]
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