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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
7mm Allen Mag test rifle finished.....
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<blockquote data-quote="Richard338" data-source="post: 76413" data-attributes="member: 1537"><p><strong>Re: wc872 burn rate</strong></p><p></p><p>BigBore,</p><p>Some more info for your info.</p><p></p><p><a href="http://www.fas.org/man/dod-101/navy/docs/fun/part16.htm" target="_blank">http://www.fas.org/man/dod-101/navy/docs/fun/part16.htm</a></p><p></p><p>Relevant excerpts</p><p>17.3.2 Propellants. </p><p></p><p>Triple-base propellants are double-base propellants with the addition of</p><p>nitroguandine to lower the flame temperature...</p><p></p><p>17.3.3 Burn Rates.</p><p></p><p>Solid propellants are designed to produce a large volume of gases at a controlled rate. </p><p></p><p>17.3.5 Interior Ballistics.</p><p></p><p>When the charge is ignited, gases are evolved from the surface of each grain of propellant, </p><p>and the pressure in the chamber rises rapidly. Due to friction and resistance of the rotating band, </p><p>the projectile does not move until the pressure behind it reaches several hundred pounds per square inch. </p><p>For a time after the projectile starts to move, gases are generated more rapidly than the rate at which </p><p>the volume behind the projectile in increased, and the pressure continues to rise...</p><p></p><p></p><p>The above info talks pretty clearly about gas production.</p><p></p><p>I didn't notice before that you said the holy grail of a pressure curve would be constant (flat until the bullet exits the muzzle).</p><p>That is the first thing dealt with in Gun Propulsion Technology in the section about how propellant is designed. </p><p>They say that naively considering that the velocity is given by the integral of the pressure curve, and that the gun can withstand only a certain max pressure one might think that a flat pressure curve is desirable. In fact it is not, and they explain why. </p><p>If you are really interested in these things you should really read that book.</p></blockquote><p></p>
[QUOTE="Richard338, post: 76413, member: 1537"] [b]Re: wc872 burn rate[/b] BigBore, Some more info for your info. [url="http://www.fas.org/man/dod-101/navy/docs/fun/part16.htm"]http://www.fas.org/man/dod-101/navy/docs/fun/part16.htm[/url] Relevant excerpts 17.3.2 Propellants. Triple-base propellants are double-base propellants with the addition of nitroguandine to lower the flame temperature... 17.3.3 Burn Rates. Solid propellants are designed to produce a large volume of gases at a controlled rate. 17.3.5 Interior Ballistics. When the charge is ignited, gases are evolved from the surface of each grain of propellant, and the pressure in the chamber rises rapidly. Due to friction and resistance of the rotating band, the projectile does not move until the pressure behind it reaches several hundred pounds per square inch. For a time after the projectile starts to move, gases are generated more rapidly than the rate at which the volume behind the projectile in increased, and the pressure continues to rise... The above info talks pretty clearly about gas production. I didn't notice before that you said the holy grail of a pressure curve would be constant (flat until the bullet exits the muzzle). That is the first thing dealt with in Gun Propulsion Technology in the section about how propellant is designed. They say that naively considering that the velocity is given by the integral of the pressure curve, and that the gun can withstand only a certain max pressure one might think that a flat pressure curve is desirable. In fact it is not, and they explain why. If you are really interested in these things you should really read that book. [/QUOTE]
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7mm Allen Mag test rifle finished.....
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