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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet Tractability
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<blockquote data-quote="Blaine Fields" data-source="post: 24272" data-attributes="member: 183"><p>No. Check out this <a href="http://www.nennstiel-ruprecht.de/bullfly/tractf.htm" target="_blank">equation</a>. Note that for a projectile to be 'tractable' it must have a tractibility factor greater than 5.1 (according to Mr. Ruprecht) and that this factor is inversely proportional to the gyroscopic stability factor. So the higher the angular velocity of any given bullet, the lower the tractibility factor. At some point, according to this equation, the bullet simply becomes fixed in space as shown <a href="http://www.nennstiel-ruprecht.de/bullfly/fig15.htm" target="_blank">here.</a> The way that I interpret this is that as long as the precessive forces don't overwhelm the pitching moments, but instead these forces are in dynamic balance, as the bullet slows and the pitching moment decreases, the bullet will close its angle of repose always with respect to its relative wind which means that as the bullet begins to decend, it will nose over in order to keep a proper angle of repose. Where the bullet is over-spun, the gyroscopic forces fix the bullet's attitude and no matter how great the pitching moment becomes, the bullet is unaffected.</p><p></p><p>Now, the foregoing may be wrong, but that is how I understand it.</p><p></p><p>I wish Warren would weigh in here. He always has something interesting to say.</p></blockquote><p></p>
[QUOTE="Blaine Fields, post: 24272, member: 183"] No. Check out this [url="http://www.nennstiel-ruprecht.de/bullfly/tractf.htm"]equation[/url]. Note that for a projectile to be 'tractable' it must have a tractibility factor greater than 5.1 (according to Mr. Ruprecht) and that this factor is inversely proportional to the gyroscopic stability factor. So the higher the angular velocity of any given bullet, the lower the tractibility factor. At some point, according to this equation, the bullet simply becomes fixed in space as shown [url="http://www.nennstiel-ruprecht.de/bullfly/fig15.htm"]here.[/url] The way that I interpret this is that as long as the precessive forces don't overwhelm the pitching moments, but instead these forces are in dynamic balance, as the bullet slows and the pitching moment decreases, the bullet will close its angle of repose always with respect to its relative wind which means that as the bullet begins to decend, it will nose over in order to keep a proper angle of repose. Where the bullet is over-spun, the gyroscopic forces fix the bullet's attitude and no matter how great the pitching moment becomes, the bullet is unaffected. Now, the foregoing may be wrong, but that is how I understand it. I wish Warren would weigh in here. He always has something interesting to say. [/QUOTE]
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Bullet Tractability
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