So, Michel, what would be the theoretical best ISP of a nitric acid/kerosene mix? Close to N2O4/kerosene or very inferior? I seem to remember an earlier exchange with you some years ago where you shared a paper that pointed out that realistically, the mix of propellant with the structure Lutz Kayser was actually going to use had a much lower ISP than the 300 range. It pointed out that with the "blowdown" pressurization system, where a fixed mass of air would expand to fill the whole volume, the pressure would drop to 1/3 the initial 40 atmospheres; at 13 1/3 atmospheres the performance of the chamber would be significantly lower. Also of course with ablative chamber and nozzle, the erosion of these surfaces would hurt performance too toward the end of the burn. Factoring all that in, the realized average ISP would be considerably lower than theoretical.