They don't support the stage, they all slide back in unison as "a ring of control surfaces" prior to entry...
Sub orbital means your payload now needs an assist-motor and now you take a hit for that.
Quote from: Rocket Science on 04/05/2017 09:11 pmIs it like the decent stage on my Dragon 2 lunar lander with a heat shield?Here is my quick-n-dirty cad model of the landed stage. So, yeah, sort of!
Is it like the decent stage on my Dragon 2 lunar lander with a heat shield?
Quote from: punder on 04/05/2017 09:27 pmQuote from: Rocket Science on 04/05/2017 09:11 pmIs it like the decent stage on my Dragon 2 lunar lander with a heat shield?Here is my quick-n-dirty cad model of the landed stage. So, yeah, sort of!Nice! How are you going to descend, chute?
Quote from: Rocket Science on 04/05/2017 09:53 pmQuote from: punder on 04/05/2017 09:27 pmQuote from: Rocket Science on 04/05/2017 09:11 pmIs it like the decent stage on my Dragon 2 lunar lander with a heat shield?Here is my quick-n-dirty cad model of the landed stage. So, yeah, sort of!Nice! How are you going to descend, chute?I was thinking propulsive landing just like (eventually) Dragon, using the SDs. The MVac does the deorbit burn, the SDs do the landing. But I must leave the dV calculations showing that to be impossible, to you guys. Perhaps a drogue would save some propellant, I don't know.In answer to the PA question... maybe little T.Rex arms that retract into the shell after payload sep?
Here is my quick-n-dirty cad model of the landed stage. So, yeah, sort of!
Quote from: punder on 04/05/2017 09:27 pmHere is my quick-n-dirty cad model of the landed stage. So, yeah, sort of!Still need a way to make sure that the center of drag is behind the center of mass so that the entry is stable. Maybe an inflatable module at the engine end, or extendable ablative airbrakes back there?
I see a lot of discussion of how to make stage 2 go nose first. But the interstage has plenty of volume around the base of the MVac, that I wonder if could be used for superdracos, fuel and legs, and to reentry-rate the Mvac bell.
Quote from: rakaydos on 04/05/2017 11:54 pmI see a lot of discussion of how to make stage 2 go nose first. But the interstage has plenty of volume around the base of the MVac, that I wonder if could be used for superdracos, fuel and legs, and to reentry-rate the Mvac bell.It's difficult (for me) to imagine how you'd leave the engine compartment open during engine operation, then cover it with a TPS for reentry. Which doesn't mean it can't be done, but it seems to require an elaborate mechanically articulated cover--which means more mass, complexity, and critical failure modes (i.e. failure to close the cover means loss of the stage.) But maybe I'm just not seeing what you mean.
Quote from: punder on 04/06/2017 02:03 amQuote from: rakaydos on 04/05/2017 11:54 pmI see a lot of discussion of how to make stage 2 go nose first. But the interstage has plenty of volume around the base of the MVac, that I wonder if could be used for superdracos, fuel and legs, and to reentry-rate the Mvac bell.It's difficult (for me) to imagine how you'd leave the engine compartment open during engine operation, then cover it with a TPS for reentry. Which doesn't mean it can't be done, but it seems to require an elaborate mechanically articulated cover--which means more mass, complexity, and critical failure modes (i.e. failure to close the cover means loss of the stage.) But maybe I'm just not seeing what you mean.Does the whole engine compartment need to be open, or just the nozzle? If just the nozzle, then can the nozzle be reinforced to survive tail-first reentry loads?(Not the engine gimbal surviving, just the nozzle- there might need to be some kind of mechanical brace that secures the nozzle from gimballing during a nozzle-first reentry)
Elon has stated his intention to develop a reusable second stage.
Quote from: Ionmars on 04/06/2017 11:03 amElon has stated his intention to develop a reusable second stage. No, he hasn't. He said they might try a Hail Mary attempt to bring back the 2nd stage, and see what happens.
Quote from: JamesH65 on 04/06/2017 11:24 amQuote from: Ionmars on 04/06/2017 11:03 amElon has stated his intention to develop a reusable second stage. No, he hasn't. He said they might try a Hail Mary attempt to bring back the 2nd stage, and see what happens.He as also stated that "they don't trow away airliners after a single use, so why should they throw away rockets" (I'm paraphrasing of course) which to me means all of it... YMMV
Quote from: Rocket Science on 04/06/2017 02:07 pmQuote from: JamesH65 on 04/06/2017 11:24 amQuote from: Ionmars on 04/06/2017 11:03 amElon has stated his intention to develop a reusable second stage. No, he hasn't. He said they might try a Hail Mary attempt to bring back the 2nd stage, and see what happens.He as also stated that "they don't trow away airliners after a single use, so why should they throw away rockets" (I'm paraphrasing of course) which to me means all of it... YMMVYes, but these are the same people who step by step worked out many of the issues with recovering boosters by getting data from boosters they expected to lose anyway. So it is perfectly possible they will simply be trying to get data from an attempt they don't seriously expect will succeed. Remember the early GTO launches where the first stage was reorienting itself after MECO, even though they weren't attempting even a sea landing?They've discarded 30+ second stages already (some are still orbiting). What we don't know is whether they gathered any information from the ones that reentered on their way down.
Maybe I'm fooling myself, but the nose-mounted recovery module just seems like a very doable, relatively inexpensive way to make the US reusable. Basically, it just replaces the Dragon 2 pressure vessel with an upside-down 2nd stage!Would be nice if someone could run the numbers. I seem to remember the US dry weight is a lot less than that of the spacecraft.