Another way to see the S2 reuse is that it paradoxically makes it easier to phase out the F9 in favor of BFR.
Quote from: Nilof on 04/17/2018 07:08 amAnother way to see the S2 reuse is that it paradoxically makes it easier to phase out the F9 in favor of BFR.If BFR is flying, you can also plausibly delete S2 recovery hardware, and recover with BFS.This lets you get the full nominal performance of the rocket, while being able to recover it, for customers that want to fly on F9.I question if this market segment exists though, as anyone really insisting on F9 is likely to want a new one.
Do you mean sending up a BFS to pick up the stranded S2 in LEO and return it to the surface? That's absolutely insane. I love it.
Elon: “This is gonna sound crazy, but ...SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon“https://twitter.com/elonmusk/status/985654333860601856?s=21
"bring rocket stage back from orbital velocity" doesn't say anything about surviving or recovering.
@elonmusk If you're proposing what I think you are, an ultra low ballistic entry coefficient decelerator, then you and @SpaceX should come see what we have at the @UofMaryland . We've been working on this for awhile and just finished some testing
@QuinnKupec @SpaceX @UofMaryland Yeah, exactly! Would be great to hear your thoughts. We’re going to try a few approaches. Can def be done, just about minimizing mass.
Absolutely! That's what we are working on right now! I would love to share with you, or anyone from @SpaceX what we are doing. Please let me know a good way to get you my contact information.
Shout-out to the UMD Nearspace team and the Balloon Payload Program! The orange payload in the image is called TARDIS, and it essentially works like an upside-down umbrella, opening up wide when falling back to earth to decelerate. Quinn's been working on this for over a year, by now
PS: I remember there being a thread discussing this sort of system for second stage recovery a few years ago, is that just me?
All lovely but one bit of concern in my mind - an extremely low ballistic coefficient
Quote from: OxCartMark on 04/18/2018 01:39 pmAll lovely but one bit of concern in my mind - an extremely low ballistic coefficientI'm 99.9999% sure that what's meant is the ballute increases the drag lots, by presenting a larger area.This causes the heat per square meter of balloon to drop, as the kilos per square meter goes from about 100kg/m^2 to about 1.
It also causes it to reenter much faster after it hits the top of the atmosphere, reducing dispersion.
Surely if it's possible to get the second stage down to sea level in one piece without using much retro-propulsion (party balloons, ballute, whatever you wanna call it) the same must be true of the first stage. Just keep enough fuel to land it, no need for any burn except to get it into the right place.Or am I being dense?
Quote from: speedevil on 04/18/2018 01:41 pmIt also causes it to reenter much faster after it hits the top of the atmosphere, reducing dispersion.No doubt once it hits the top of the atmosphere (which is a squishy border but high up in this case because of the very low loading) that'll be the case but the large variability occurs before that time in the re-entry, when the speed is very high and the atmospheric density is just a slight bit more than negligible.
Does any one have any good sources for the mass of steerable parafoils and/or the mass of the second stage? From the sounds of it, this system will use either a huge ballute to reduce peak heating to below 500oC (well below the melting temperature of Aluminium and removing the need for a heat shield) or a smaller deployable heat shield like HIAD*.