Quote from: Cheapchips on 04/16/2018 07:19 AMWill the nozzel survive this type of entry and bouncy landing? It uses strengthening rings for launch. Can they keep those in place instead of discarding them at S2 ignition?I'd imagine that the nozzel is one of the more extensive and difficult to manufacture element of the 2nd stage, next to the rest of the Mvac.The nozzle *extension* is a very simple thing. Remember when they sent an engineer into the interstage to cut it short with some tin snips?If they can reliably jettison it, they can easily fit a new one.
Will the nozzel survive this type of entry and bouncy landing? It uses strengthening rings for launch. Can they keep those in place instead of discarding them at S2 ignition?I'd imagine that the nozzel is one of the more extensive and difficult to manufacture element of the 2nd stage, next to the rest of the Mvac.
My thought was around cost and easy of manufacture. Niobium alloy isn't cheap or easy to work with.
Quote from: Crispy on 04/16/2018 08:53 AMQuote from: Cheapchips on 04/16/2018 07:19 AMWill the nozzel survive this type of entry and bouncy landing? It uses strengthening rings for launch. Can they keep those in place instead of discarding them at S2 ignition?I'd imagine that the nozzel is one of the more extensive and difficult to manufacture element of the 2nd stage, next to the rest of the Mvac.The nozzle *extension* is a very simple thing. Remember when they sent an engineer into the interstage to cut it short with some tin snips?If they can reliably jettison it, they can easily fit a new one.My thought was around cost and easy of manufacture. Niobium alloy isn't cheap or easy to work with.
Another cross connection - someone noticed crates from Airtech International Inc. at the BFR manufacturing site. I just checked their website and they offer vacuum bagging for composite manufacture. They offer bagging(Polyimide) that is resistant to 426°C, has great tensile strength etc.Its intended for vacuum...
It could be an annular ballute fitted around the engine, which then hangs the stage nose first. The engine would then be largely protected. Annular ballutes have I believe mass and volume advantages over a sphere.
Quote from: Bananas_on_Mars on 04/16/2018 07:07 AMAnother cross connection - someone noticed crates from Airtech International Inc. at the BFR manufacturing site. I just checked their website and they offer vacuum bagging for composite manufacture. They offer bagging(Polyimide) that is resistant to 426°C, has great tensile strength etc.Its intended for vacuum...Well spotted. What a remarkable operating temp for a plastic (assuming that's in air, not vacuum). If it's true that it's mainly a case of being thin enough to radiate the heat away then this does sound exactly what you'd need to make this work.
Kapton is used in, among other things, flexible printed circuits (flexible electronics) and thermal blankets used on spacecraft, satellites, and various space instruments.
Will the nozzle survive this type of entry and bouncy landing? It uses strengthening rings for launch. Can they keep those in place instead of discarding them at S2 ignition?I'd imagine that the nozzel is one of the more extensive and difficult to manufacture element of the 2nd stage, next to the rest of the Mvac.
Second stage re-usability would likely incorporate re-using the fairings. Which essentially, we're looking at a mini BFS in configuration.
If re-usability centers around capturing the fairings with the seaborne net, then the second stage would have to have a heat shield at the front of the stage, protection for the nozzle, and superdrakos for landing. My bet would be the mini BFS, if they even pursue this option.
Elon Musk@elonmusk12h12 hours agoThis is gonna sound crazy, but …SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloonAnd then land on a bouncy house.
There is another reason, which is that they discovered they still had the bandwidth to do it despite the pivot to BFR.
Quote from: Cheapchips on 04/16/2018 06:37 AMThere is another reason, which is that they discovered they still had the bandwidth to do it despite the pivot to BFR.Another reason would be that the F9/FH family have a long future ahead of them. I think it’s at least 5 years before BFR flys a paying payload. The US would likely only be reuseable on low energy, small payload missions, at best. But that’s enough to make it worth while. Especially if you get the US back then smaller payload launch costs can be even lower than now. Maybe they get the fairing figured out before jumping to this step. Edit: imagine the launch cost for smaller or LEO payloads if they can recover the booster, fairing and US. My gosh, it could eventually be maybe $20 million or less with time. Edit 2: It's likely fair to think that for chance of US reuse that RTLS would give way to ASDS recovery. Make the booster do as much work as possible and give the US as much margin as possible. I think this whole idea is marginal at best, but it would be great fun to try.
Second stage re-usability would likely incorporate re-using the fairings. Which essentially, we're looking at a mini BFS in configuration. The weight penalty would be enormous for the F9, but Falcon Heavy could handle the payload penalty. If re-usability centers around capturing the fairings with the seaborne net, then the second stage would have to have a heat shield at the front of the stage, protection for the nozzle, and superdrakos for landing. My bet would be the mini BFS, if they even pursue this option.
Back to F9US reuse. If he shows a crisped,wet US to park next to the booster out in front of SX in Hawthorne, the analysts will trot by for pics with Musk and them, chat up an insane valuation, and his ability to raise $40-50T goes online at that point.
I'm not sure why everyone seems to take it as a given that this upper stage recovery is only for GEO missions.When SpaceX launches a satellite destined for GEO, it doesn't do a direct GEO insertion. It releases the satellite in GTO. So the upper stage is in a highly elliptical orbit with its low point pretty close to Earth. If it inflates a giant balloon of some shape, it can do many passes grazing the atmosphere to lose speed and slow down until it's in a circular low-Earth orbit, and then go for re-entry.This assumes both the stage and the balloon can last a while in space. Maybe that's realistic, maybe not, but I wouldn't discount it out-of-hand as impossible.