Dynamics of Rigid Guns with Straight Tubes
Interim rept. Nov 1980-Nov 1981
BLM APPLIED MECHANICS ASSOCIATES LARAMIE WY
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Each of the four sections in this report deals with the motion, the forces, and the moments experienced by a rigid gun with a straight axis and an offset breech, and with a certain simple type of support that attaches the gun to a Galilean reference frame. The analysis treats the behavior of the system while the projectile is in the barrel. After the projectile leaves the muzzle, its motion and that of the gun are independent, and they may be analyzed by the dynamical theory of a single rigid body. The motion of the projectile with respect to the tube is regarded as known. Also, the base pressures on the projectile and the tube are regarded as known functions of time. Geometrically, the projectile is regarded as a body of revolution that fits snuggly in the tube, so that there is no balloting, However, a lopsided distribution of mass density in the projectile is admitted in Sections 1,2, and 3. In Section 4, only a balanced projectile is considered. In applications of the momentum principles, the momentum of gases in the tube is neglected. It can be introduced empirically by augmenting the mass of the projectile by a portion of the mass of the charge. This concept of effective mass has a precedent in other branches of fluid mechanics.