Second stage should be reused in orbit: so much effort to put it up there, why bring it back just to relaunch? Carry a little more spare fuel and "park" it somewhere, then follow up with a second launch from earth with only payload and fuel, randez vous and join, you spare the engine and avionics, and their weight.Do exist orbit and timings to do that ? I don't know
I had long struggled to think of a really good configuration for the fully reusable second stage. Unstable nose first or hard to shield engine end first
The fairing could fly around and swallow the second stage, engine end first, before re-entry.
A couple of differences I wouldn't be surprised by in a real reusable upper stage are a fatter front end with a taper toward the rear, and landing thrusters near the top.
Not much. I liked that suggestion in the thread that it might be more Dragon-like. If I was bringing new information rather than speculating, I'd have referenced my source.Have you ever seen a completely cylindrical reentry vehicle?I haven't, and that is pretty close to being the extent of my reasoning process.
What's wrong with SpaceX's configuration (see attached photo)?
Better to invest money in a re-startable, cryo second stage than a reusable one. Not all second stages are coming back anyway.
Have you seen a tapered pressurized tank that supports a load on both ends?
Quote from: Jim on 06/21/2013 06:13 pmHave you seen a tapered pressurized tank that supports a load on both ends? ?
Quote from: Jim on 06/21/2013 06:13 pmHave you seen a tapered pressurized tank that supports a load on both ends?If you want to explain why you think it would be a problem, I'm interested in hearing it.
To minimize g forces on re-entry you don't want your heat shield diameter to be any larger than necessary.
Semyorka, Molnia, Polyot, Vostok, Soyuz.
Quote from: bubbagret on 06/21/2013 06:29 pmSemyorka, Molnia, Polyot, Vostok, Soyuz.Those don't rely on internal pressure for support.
So we are only equating Atlas 1, and Centaur type structures to F9-S2? I didn't realize that.
Whereas the Soyuz is built like a tank and can support people walking on it.