[FrojoS]

Thanks a lot. Very interesting!

> For this reason you usually have a large imbalance of one propellent to the other to keep the temperature down.

So how large is that imbalance usually, or in the case of the Merlin 1C?

> although the Space Shuttle Main Engines are a US-design example of Staged combustion.

Is this, why their exhaust is so clean? How much more efficient is this engine compared to the Merlin?

PS: I'm excited, this engine will be used again in the new super heavy lift [1] that NASA is developing, though obviously, I can't tell if its a good idea.

[1] http://en.wikipedia.org/wiki/Space_Launch_System#Core_stage

[schiffern]

>Is this, why their exhaust is so clean?

The Space Shuttle Main Engines used LOX and LH2, which creates water when burned.

>How much more efficient is this engine compared to the Merlin?

The specific impulse is the metric to look at, and ballooney already talked about it.