IX. A theory of internal ballistics based on a pressure-index law burning for propellants
It has been felt for some time past that an extension of the present internal ballistic theory is necessary to take into consideration the case of propellants which do not burn according to the simple law generally adopted for M.D. Cordite. This law, which makes the rate of reduction of the smallest linear dimension of a piece of propellant proportional to the first power of the gas pressure, renders the mathematical treatment of the ballistic problem, both as regards the closed vessel and the gun, comparatively easy. The law of burning must, however, from the nature of the case, be a more complicated phenomenon than is thus pre-supposed, and in the present paper the problem has been investigated assuming a rate of burning proportional to some power, less than unity, of the gas pressure. It is not pretended that such an assumption leads to finality, but in view of the many attempts made, chiefly by continental writers, to consider internal ballistics on this basis, and also since experiment seems to suggest such a law for many propellants, it was thought worth while to present a connected account of an investigation into this subject.