Evaluation of the Burning Rate of Black Powder used in Polish Artillery in the 17th Century

Theoretical studies of the propulsion of a projectile in the barrel for a gun propellant system can be realized by numerically solving a system of equations that describe the phenomena occurring in the barrel space behind the projectile during firing. The accuracy of the solution of the mathematical model of the shot depends on reliable input data including the mass-geometric characteristics of the elements of the gun propellant system and the energy-ballistic characteristics of the gun propellant used. The present article addresses the problem of modelling the phenomenon of firing in a black-powder cannon from the 17th century. The acquisition of real input data, including the mass-geometric characteristics of the elements of the black-powder cannon is possible based on historical descriptions and preserved weapons in museums. In relation to the black powder used in 17th century artillery, although we have knowledge of the content of its components, there is no literature information on the value of its energy-ballistic characteristics. The purpose of this article is to determine the form of the burning rate law for the black powder used in Polish artillery in the 17th century and to compare the results obtained with available data on contemporary black powder. The procedure used was the so-called inverse solution of the gun interior ballistic model, in which, on the basis of the identified tactical-technical characteristics of the known blackpowder cannon, the values of the force and covolume obtained by thermochemical calculations, and the assumed shape of the black powder grains, the values of the coefficient and exponent of the burning rate law were determined.