First Law of Rocketry - While the engine is running at no time can the pressure in the expansion chamber ever exceed the out pressure of the main fuel pump.
First Law of Rocketry - While the engine is running at no time can the pressure in the expansion chamber ever exceed the out pressure of the main fuel pump.
Otherwise a Bad Thing will happen.
What happens if the pressure in the expansion chamber exceeds the out pressure of the main fuel pump? Does the fuel go back into the main fuel pump? That could cause a mess!