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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
New Software Development Request
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<blockquote data-quote="groper" data-source="post: 417061" data-attributes="member: 12550"><p>Indeed, us pilots call it 'wind gradient' for the exact reasons you describe. You can really feel it when you take off from a cleared forest airstrip surrounded by tall trees. As you climb say 100ft above the tree line you could get as much as an extra 15mph of wind... It should be something to consider where your bullet flight is in a particular environment where this is prevalent.</p><p></p><p></p><p></p><p>Mikecr, take a 1200yd shot for example... using my .308 and using my ballistic calc, my bullet flys thru the first 400yds in approx 0.49 secsonds.</p><p></p><p>From 400yds - 800yds, the same bullets takes 0.65 seconds for this middle leg.</p><p></p><p>And the last part of its flight from 800 - 1200yds, it spends a whopping 0.90 seconds. Total flight time = 2.04 seconds.</p><p></p><p>So it takes almost twice the time to complete the last 1/3 of its flight compared the the first 1/3. This means whatever wind is present during the last 1/3 has almost twice the time to apply its vector and drift acceleration on the bullet.</p><p></p><p>Furthermore, as the bullet slows down its BC decreases, so in the last part of its flight it not only has to be effected by the wind for longer but the wind can push it more easily due to a lower BC.</p></blockquote><p></p>
[QUOTE="groper, post: 417061, member: 12550"] Indeed, us pilots call it 'wind gradient' for the exact reasons you describe. You can really feel it when you take off from a cleared forest airstrip surrounded by tall trees. As you climb say 100ft above the tree line you could get as much as an extra 15mph of wind... It should be something to consider where your bullet flight is in a particular environment where this is prevalent. Mikecr, take a 1200yd shot for example... using my .308 and using my ballistic calc, my bullet flys thru the first 400yds in approx 0.49 secsonds. From 400yds - 800yds, the same bullets takes 0.65 seconds for this middle leg. And the last part of its flight from 800 - 1200yds, it spends a whopping 0.90 seconds. Total flight time = 2.04 seconds. So it takes almost twice the time to complete the last 1/3 of its flight compared the the first 1/3. This means whatever wind is present during the last 1/3 has almost twice the time to apply its vector and drift acceleration on the bullet. Furthermore, as the bullet slows down its BC decreases, so in the last part of its flight it not only has to be effected by the wind for longer but the wind can push it more easily due to a lower BC. [/QUOTE]
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