Quote from: Kaputnik on 04/01/2017 02:13 pmIf i'm visualising this correctly, it puts too much surface area ahead of the centre of gravity, and the stage would be extemely unstable and want to fly backwards.For sure if they come in engine first it can not survive reentry. It would need to be sideways somewhat like ITS and IXV reentry, with flaps doing the steering and protecting the engine. It needs a heatshield on the side of the stage.
If i'm visualising this correctly, it puts too much surface area ahead of the centre of gravity, and the stage would be extemely unstable and want to fly backwards.
Or an aft mounted toroidal inflatable skirt using similar technology to HIAD, and a forward mounted Pica-X heatshield.
This a a modification of a Flyback Falcon I made up 6 years back using an X-37 like mold line for S2 before F9R. The current S2 would slide in the external airframe and land on a runwayhttps://forum.nasaspaceflight.com/index.php?topic=27477.20
Quote from: mr. mark on 04/01/2017 06:11 pmClearly SpaceX already has a second stage prototype ready to go. You just don't slap things on to an existing stage. This brings up an important point. Is SpaceX conducting super secret testing such as a black ops program for future designs away from the public eye.I seriously doubt that. He wouldn't have called it "hail mary" then. Spacex doesn't have the time or resources to seriously devote to a one off hail mary attempt right now. I think it's more likely Elon is considering giving a couple of interns access to a used dragon and a healthy budget of zero, telling them to make something happen. Thinking it might be worth to fly that in lieu of a couple of extra tons of cheese (cheese is expensive you know).
Clearly SpaceX already has a second stage prototype ready to go. You just don't slap things on to an existing stage. This brings up an important point. Is SpaceX conducting super secret testing such as a black ops program for future designs away from the public eye.
How hard would it be to re-engineer stage 2 to have an oxygen drop tank?Would the remaining heat-shield, fuel tank, engine, nozzle have shifted the centre of gravity far enough backwards to be passively stable on re-entry? It would definitely look more like a shuttlecock.Could the nozzle act like grid fins?
thought as much. so might be simpler to drop both and have the heat shield between the tanks and engine. How would they plumb that?shame to lose the tanks, but still a lot of value in the remainder.(maybe dock the detachable tanks with the engine bell to sort out the c-of-g.)
Quote from: gin455res on 04/02/2017 09:46 amthought as much. so might be simpler to drop both and have the heat shield between the tanks and engine. How would they plumb that?shame to lose the tanks, but still a lot of value in the remainder.(maybe dock the detachable tanks with the engine bell to sort out the c-of-g.)So essentially apply the ULA Vulcan plan to the US.