A simplified expression (Equation 20) is presented for rapid determination of an erosion constant k from zero-time steady-state motor firings obtained at various port-to-throat ratios. Application of this method to data obtained on a poly-urethane propellant shows that k is constant at 1.10 up to H = 3, beyond which it increases linearly with H.
Blatz, P. J. (1961). A simplified approach to erosive burning. In Symposium (International) on Combustion (Vol. 8, pp. 745–753). https://doi.org/10.1016/S0082-0784(06)80568-0