Jane-DoH
And this goes to show why obsessing on economics is not always the best course of action.
Proponents of SSTO argue for it because, they claim, that it must be a more
economical way to get to space and some of us argue the opposite.
By the way, engineering vs. science: engineering has to contend with a plethora of diverse parameters to optimize. It's a dream when a customer says "cost is no object". Usually, it is an issue.
If we followed our lives strictly by economics, old people, sick people, and mental ill people would probably be euthanized -- after all it costs a lot of money to keep these people alive and take care of them
Let's try to keep this in the spirit of Tech Log.
A plane/launcher being destroyed after their useful lifetime is over is sad. But let's not get overboard by comparing them with euthanasia of living people.
You're right about
...transfer the heat into LH2 heading towards the engine...
It makes more sense too (now that I'm looking at the diagram and not shooting from the hip
).
About pre-burners in jet engines: unless I mixed up the terms, such devices were used at least in the early designs. It had something to due with difficulty of injecting liquids into the chamber and getting a good mixing. With a pre-burner, they were injecting gas and the mixing was easy(ier). At least that's what I read. When I find where, I'll post it, but I'm sure we have real experts here who could clarify the issue.