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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Epicyclic motion of a bullet (video)
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<blockquote data-quote="BryanLitz" data-source="post: 251242" data-attributes="member: 7848"><p>Just playing around with the 6 Degree Of Freedom simulation and learning how to make video's from the output.</p><p></p><p><a href="http://www.youtube.com/watch?v=4pF8W5liSRc&feature=channel_page" target="_blank">click here to view the video.</a></p><p></p><p>The link is to a dynamic plot of the pitching and yawing motion of a bullet fired with an initial yaw rate of 25 radians per second (about 1,433 degrees per second). You can watch the bullet damp the yaw cycles from a maximum of over 3 degrees to less than 1 degree at 200 yards. This is the process commonly referred to as the bullet 'going to sleep'.</p><p></p><p>As for how realistic/common a 25 rad/s initial yaw rate is, I can't say. The motion produced by such a 'tip-off' rate only acts to reduce the effective BC by less than 1% in the first 100 yards, and not at all beyond that. A shot with 25 rad/s initial yaw rate only strikes about 0.75" from a bullet launched with no yaw at 100 yards. If the initial yaw were randomly oriented, this would produce a radius of dispersion of 0.75", and a 1.5" c-t-c group. However, if the initial yaw rate is always in the same direction, then the shots could form a group much smaller than 1.5".</p><p></p><p>I suspect that thinner, lighter weight 'whippier' barrels would tend to produce higher levels of initial pitch/yaw than a heavy bull barrel like we use in competition.</p><p></p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 251242, member: 7848"] Just playing around with the 6 Degree Of Freedom simulation and learning how to make video's from the output. [URL="http://www.youtube.com/watch?v=4pF8W5liSRc&feature=channel_page"]click here to view the video.[/URL] The link is to a dynamic plot of the pitching and yawing motion of a bullet fired with an initial yaw rate of 25 radians per second (about 1,433 degrees per second). You can watch the bullet damp the yaw cycles from a maximum of over 3 degrees to less than 1 degree at 200 yards. This is the process commonly referred to as the bullet 'going to sleep'. As for how realistic/common a 25 rad/s initial yaw rate is, I can't say. The motion produced by such a 'tip-off' rate only acts to reduce the effective BC by less than 1% in the first 100 yards, and not at all beyond that. A shot with 25 rad/s initial yaw rate only strikes about 0.75" from a bullet launched with no yaw at 100 yards. If the initial yaw were randomly oriented, this would produce a radius of dispersion of 0.75", and a 1.5" c-t-c group. However, if the initial yaw rate is always in the same direction, then the shots could form a group much smaller than 1.5". I suspect that thinner, lighter weight 'whippier' barrels would tend to produce higher levels of initial pitch/yaw than a heavy bull barrel like we use in competition. -Bryan [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Epicyclic motion of a bullet (video)
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