On Sat, 28 Sep 2002, Doug Jones wrote: > On shutdown, the only command needed is to either close the main valves > (as on the EZ-Rocket), or simply to turn off the Main Open command (as > is usual when using pneumatic actuated 4-way solenoid piloted valves). > As the propellant pressures drop, the purge relief valves reopen and > sweep out the residuals. When all is clear, then you disable the purge- > excess purge just wastes a bit of inert gas, not a big deal.
If the length of the plumbing between valve and injector is different for fuel & ox, then simultaneous shutdown of the main valves ought to lead to a timing difference in the shutdown _at_the_injectors_. This obviously glosses over issues like differences in plumbing diameter, propellant viscosity, fuel/ox mixture ratio, etc, but it illustrates the point. For a regen HTP biprop, the additional volume in the engine cooling passages ought to make it relatively simple to ensure that a scram shutdown with purge leads to fuel exhaustion well before HTP exhaustion. IOW if there is substantially more volume in the HTP plumbing between main valve and injector then between fuel valve and injector, then the purge you describe ensures that in most scram scenarios the catpack is protected. ......Andrew -- Andrew Case | [EMAIL PROTECTED] | _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
