If SpaceX does build up an inventory of 30 or more Falcon 9 first stages, where will they keep them? That is a lot of floor space. I suppose some will be at Vandenberg and some in Florida but what will the split be and where will the hangers be? Surely they won't store them outside in the weather and using tents in Florida doesn't sound like a good idea long term.Mods: This post may need to be moved, please do so if there is a better thread for it. Thanks.
Quote from: aero on 06/17/2018 04:28 pmIf SpaceX does build up an inventory of 30 or more Falcon 9 first stages, where will they keep them? That is a lot of floor space. I suppose some will be at Vandenberg and some in Florida but what will the split be and where will the hangers be? Surely they won't store them outside in the weather and using tents in Florida doesn't sound like a good idea long term.Mods: This post may need to be moved, please do so if there is a better thread for it. Thanks.Hangars are cheap.
Quote from: mme on 06/15/2018 06:19 pm...I imagine the R&D is currently being done "on the cheap." The beauty of US reuse is it means that you can shut down the production lines sooner. Assuming that the attrition rate is low enough to keep flying well past any BFR delays this is the difference between making 75 more upper stages versus 300 more. [1]...Hey, if they can get it to work I'm all in. However, can one do recovery of orbital equipment on the cheap?Pick some numbers, if a US costs $10 million and it costs a few hundred million to develop recovery, if it works at all, is it worth it? Even if it can be recovered what will it cost to reuse for each mission, what's the net benefit to recover the cost?Like I said I'm all for it, but I can see the business case not working out.
...I imagine the R&D is currently being done "on the cheap." The beauty of US reuse is it means that you can shut down the production lines sooner. Assuming that the attrition rate is low enough to keep flying well past any BFR delays this is the difference between making 75 more upper stages versus 300 more. [1]...
Quote from: wannamoonbase on 06/15/2018 07:23 pmQuote from: mme on 06/15/2018 06:19 pm...I imagine the R&D is currently being done "on the cheap." The beauty of US reuse is it means that you can shut down the production lines sooner. Assuming that the attrition rate is low enough to keep flying well past any BFR delays this is the difference between making 75 more upper stages versus 300 more. [1]...Hey, if they can get it to work I'm all in. However, can one do recovery of orbital equipment on the cheap?Pick some numbers, if a US costs $10 million and it costs a few hundred million to develop recovery, if it works at all, is it worth it? Even if it can be recovered what will it cost to reuse for each mission, what's the net benefit to recover the cost?Like I said I'm all for it, but I can see the business case not working out.Using 10 million per US, building 225 fewer upper stages saves 2.25 billion dollars (minus whatever recovery of those stages cost.) And it shuts down two production lines (vacuum Merlin and US) sooner freeing up people to work on Raptors, BFS and BFR.
Quote from: mme on 06/17/2018 05:18 pmQuote from: wannamoonbase on 06/15/2018 07:23 pmQuote from: mme on 06/15/2018 06:19 pm...I imagine the R&D is currently being done "on the cheap." The beauty of US reuse is it means that you can shut down the production lines sooner. Assuming that the attrition rate is low enough to keep flying well past any BFR delays this is the difference between making 75 more upper stages versus 300 more. [1]...Hey, if they can get it to work I'm all in. However, can one do recovery of orbital equipment on the cheap?Pick some numbers, if a US costs $10 million and it costs a few hundred million to develop recovery, if it works at all, is it worth it? Even if it can be recovered what will it cost to reuse for each mission, what's the net benefit to recover the cost?Like I said I'm all for it, but I can see the business case not working out.Using 10 million per US, building 225 fewer upper stages saves 2.25 billion dollars (minus whatever recovery of those stages cost.) And it shuts down two production lines (vacuum Merlin and US) sooner freeing up people to work on Raptors, BFS and BFR.Realistically they can only recover upper stages of LEO stages, OR for most GTO missions they will have to switch from F9 to FH to allow upper stage recovery,.And for the heaviest satellites to GTO with full reusability of FH is simply impossible, not enough capacity in fully reusable mode.This means costs related to upper stage reuse are considerably greater for many of their missions, and they cannot recover it for all mission.
Going by Elon's statements on twitter - there are no mentions of 2nd stage wings. Only a party balloon and landing on a bouncy house (which so far have been taken to mean a ballute). It would be fair to presume that they didn't consider the ballute until recently.
He's also mentioned that they want to keep the mass down on any 2nd stage recovery system. It looks doubtful that they would proceed with it if it did take a massive payload hit or need a major redesign
Using 10 million per US, building 225 fewer upper stages saves 2.25 billion dollars (minus whatever recovery of those stages cost.) And it shuts down two production lines (vacuum Merlin and US) sooner freeing up people to work on Raptors, BFS and BFR.
SpaceX stated they are planning to shutdown F9 booster production to concentrate on BFR. That means in the future they will have a vehicle inventory for all future flights.
Wings on an F9 US? C'mon, you've been posting in this thread and replying to discussions about HIAD and other methods. Stop making stuff up.
Quote from: RonM on 06/16/2018 06:51 pmAs long as F9 is flying, there will be some FH cores available. They can refuse flights that would expend the FH core.AIUI SX doesn't really do "inventory." They make to order. If it can be recovered and reflown, great. The only FH flown had a new build core. That's still available (I guess) but how many more did they build?Quote from: RonMSpaceX should look into F9 US reuse. While I'm confident in BFS flying, it's schedule is pretty optimistic. Good chance F9 and FH will be in use longer than the current plan.SX have been looking at US recovery and reuse. During 2011-2014 they thought they could. Then musk announced it was off the table for any F9 based architecture. Recently it seems it's back on the table, maybe. Given that SX couldn't manage to do it with BFS without adding wings despite increasing its size about 7x (and new, high Isp engine with better fuel) that suggests the only viable way to do F9 recovery is likewise to put wings on it.And that's going to be a massive payload hit and effectively a complete stage redesign.
As long as F9 is flying, there will be some FH cores available. They can refuse flights that would expend the FH core.
SpaceX should look into F9 US reuse. While I'm confident in BFS flying, it's schedule is pretty optimistic. Good chance F9 and FH will be in use longer than the current plan.
That "1:1 mass penalty" meme is very misleading when applied to LEO launches.First of all, LEO launches are often volume limited, and then there's no penalty at all since the extra mass would have been wasted anyway.Second, LEO launches can put some 20 tons in orbit, and the second stage has a dry mass of 5 tons. Instead of counting tons, count fractions. If the stage takes a 50% mass penalty (bringing it to 7.5 tons), the payload goes from 20 to 17.5 tons. That's not exactly the end of the world.My money is on a towed balloon, maybe with some active system to prevent gyrations, and said system being used mostly for LEO (constellation) launches.
Good point, but that was also the case with all first stage rocket nozzles until SpaceX tried it with their S1. Admittedly the S2 vac nozzle is much longer and I would guess less good at withstanding those stresses flying backwards, but who knows until they try it..Why is there such minimal heat-shielding on S2? Is radiative heating less of an issue than hot gas recirculation? What base heat shielding is there generally on the bottom of a rocket booster that isn't designed to return tail first?
Remember that BFS is designed for maximum-payload EDL for Mars, not Earth. Two very different regimes, design changes to optimise BFS for Mars entry from interplanetary velocities may not be optimal (or even counterproductive) for Earth EDL from orbital velocities.
Quote from: edzieba on 06/18/2018 12:21 pmRemember that BFS is designed for maximum-payload EDL for Mars, not Earth. Two very different regimes, design changes to optimise BFS for Mars entry from interplanetary velocities may not be optimal (or even counterproductive) for Earth EDL from orbital velocities.It really wasn't.Unless you choose to entirely ignore IAC2017 and P2P, which in concert with the later tweet about 'adding an engine for safe engine out landing' pretty much implies landing nearly maximum weight BFS on earth, repeatedly.It is also an interesting coincidence that reentry from GTO, and reentry from interplanetary transit from Mars are comparable, as are reentry from LEO and interplanetary entry to Mars.(at least at near minimum energies).
That "1:1 mass penalty" meme is very misleading when applied to LEO launches.Second, LEO launches can put some 20 tons in orbit, and the second stage has a dry mass of 5 tons. Instead of counting tons, count fractions. If the stage takes a 50% mass penalty (bringing it to 7.5 tons), the payload goes from 20 to 17.5 tons. That's not exactly the end of the world.My money is on a towed balloon, maybe with some active system to prevent gyrations, and said system being used mostly for LEO (constellation) launches.
Quote from: meekGee on 06/18/2018 06:40 amThat "1:1 mass penalty" meme is very misleading when applied to LEO launches.Second, LEO launches can put some 20 tons in orbit, and the second stage has a dry mass of 5 tons. Instead of counting tons, count fractions. If the stage takes a 50% mass penalty (bringing it to 7.5 tons), the payload goes from 20 to 17.5 tons. That's not exactly the end of the world.My money is on a towed balloon, maybe with some active system to prevent gyrations, and said system being used mostly for LEO (constellation) launches.You make it sound like childs play if they have that much margin to play with.And yet somehow they are still struggling 7 years after they thought they could do it.Is it possible there are things about this problem you're missing that make it substantially more difficult?