balsa model
roponents 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.
Well, it isn't. Still, I wouldn't want to be junking too many spacecraft. There are only so many resources available on earth.
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.
I wasn't comparing the loss of an expendable plane to euthanasia; I was simply saying that if life was lived purely by economics... well you get the idea. I personally think anything taken to excess is generally bad.
You're right about
Which keeps bringing me back to one main issue: Wouldn't that be a lot of heat to be transferring into the LH2 that's going to be heated additionally by burning it in the engine's combustion chamber? You'd be absorbing a couple of hundred degrees from the outside air temperature when you're just running the engines on the tarmac -- when you get up to Mach 5, you'd have another 600 degrees extra to drain away from the airflow and transfer into the LH2. Would that have an adverse effect on driving up turbine temperatures?
Honestly, it seems more practical to just tap the heat off the liquid helium, transfer it to the LH2 (as well as combustion chamber temperatures) to just vaporize it, then drive an expansion turbine off that. It looks like it would simplify things and would best exploit the extremely low temperatures of the Liquid Helium and LH2 in the cycle.
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).
So they used a small pre-burner to vaporize the fuel so it would burn easier?
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.
Yeah