But it's not combustion. I guess you meant something else. Now you label they approach; do you think laying boundary line this way looks obviously correct? Say,

But it's not combustion. I guess you meant something else. Now you label they approach; do you think laying boundary line this way looks obviously correct? Say, nuclear rocket engines heat up gases - also without chemical reaction; resistor jets also have reasonable history in rocketry - why ARCA's approach is wrong?