mikegarrison Posted August 21, 2019 Share Posted August 21, 2019 My best guess is that Falcon 9 launches provide a positive cash flow, and the company is using that cash to pay for these Starship and Starlink projects, which they hope will provide a good enough cash flow to pay for their next projects, ad infinitum. This is the same business model that most manufacturing companies have. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 (edited) 20 minutes ago, tater said: SpaceX exists to create a multiplanetary humanity Motto =/= aim. Like it's said, "if your soul is flying to skies, keep your eye on your body below, maybe somebody wants to steal it." Edited August 21, 2019 by kerbiloid Quote Link to comment Share on other sites More sharing options...
tater Posted August 21, 2019 Share Posted August 21, 2019 11 minutes ago, kerbiloid said: Motto =/= aim. Like it's said, "if your soul is flying to skies, keep your eye on your body below, maybe somebody wants to steal it." SpaceX and Blue Origin are fundamentally different than other launch providers in history, IMO. Government agencies have domestic priorities that are, well, political, and they have international priorities that are geopolitical. The "usual suspect" defense contractors have their own concerns. In the US, they are public, and have to provide value to shareholders, so existing to harvest money from the government is understandable. Their prices don't in fact always reflect costs, but what the government is used to paying (watch spending at US National labs near the end of the fiscal year, lol, as everyone junks stuff they bought new last June for the same reason, and buys the latest model only a little better than what they are junking). Commercial providers as stand-alones are new, and the ones currently operating are mostly tied to governments, or are small outfits (RocketLab, etc). I think the goals/aims of SpaceX/BO are indeed what they are literally doing it for. It's very clear in the case of Bezos, he outright says it's a sort of long-thinking philanthropy, and he's doing it with huge sums that are in fact trivial to him. SpaceX has a similar goal, but since they don't have a "free" billion a year in play money, they have to have a business model that provides them with a rocket factory to play with. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 (edited) 4 minutes ago, tater said: I think the goals/aims of SpaceX/BO are indeed what they are literally doing it for. It's very clear in the case of Bezos, he outright says it's a sort of long-thinking philanthropy, and he's doing it with huge sums that are in fact trivial to him. Afai can see, BO is a pet project of a billionaire having enough good source of money. No problem. But it looks like his vis-a-vis owns a whole zoo of pets. Edited August 21, 2019 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Flying dutchman Posted August 21, 2019 Share Posted August 21, 2019 (edited) @mikegarrison Is it your opinion that we should stick to expendable rockets? Edited August 21, 2019 by Flying dutchman Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted August 21, 2019 Share Posted August 21, 2019 1 minute ago, Flying dutchman said: @mikegarrison Is it your opinion that we should stick to expendable rockets? Not generally, no. But all rockets are at least in part (the fuel) expendable. And no orbital launch systems to date have not expended at least some major components. In general I'm an environmentalist, so I like "reuse, recycle" a lot. Quote Link to comment Share on other sites More sharing options...
Nothalogh Posted August 21, 2019 Share Posted August 21, 2019 5 hours ago, kerbiloid said: (without the shield, so afaik the engines are partially on) What does this even mean? Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 1 minute ago, Nothalogh said: What does this even mean? Does Falcon have a heatshield or bottom shroud? Does it burn its engines while aerobraking? Quote Link to comment Share on other sites More sharing options...
Nothalogh Posted August 21, 2019 Share Posted August 21, 2019 10 minutes ago, kerbiloid said: Does Falcon have a heatshield or bottom shroud? Does it burn its engines while aerobraking? No, and No Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 2 minutes ago, Nothalogh said: No, and No https://space.stackexchange.com/questions/13935/how-does-the-falcon-9-first-stage-avoid-burning-up-on-re-entry Quote Link to comment Share on other sites More sharing options...
Nothalogh Posted August 21, 2019 Share Posted August 21, 2019 Just now, kerbiloid said: https://space.stackexchange.com/questions/13935/how-does-the-falcon-9-first-stage-avoid-burning-up-on-re-entry That is not what you were trying to claim. The Falcon 9 first stage initiates engine burns at three points during landing. Once to align its entry trajectory, once to decelerate before encountering the thick atmosphere, and once for the suicide burn at landing. That is it. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 I'll copy it from there to here. Quote That's still up around Mach 5 or 6, though, which produces a lot of heat. So the rocket fires three of its engines to slow down further before entering the thicker part of the atmosphere. The exhaust plume from that burn, as well, forces the atmospheric compression that creates reentry heat to occur well away from the rocket. The end result is that the heat load is light enough that the body of the rocket can survive it. There's a protective shell on the underside of the rocket, rather than a heavyweight ablative heat shield. The engine bells themselves are bearing the brunt of what reentry heat there is, and they are obviously able to cope with very high temperatures. That's exactly what I mean. Quote Link to comment Share on other sites More sharing options...
Thor Wotansen Posted August 21, 2019 Share Posted August 21, 2019 @kerbiloid I am 100% certain that reuse of the Falcon 9 first stage is increasing SpaceX's profits. You mentioned the cost of the engines earlier, saying that if you take one or two off and reduce the tank size by 15% you'd save in the long run. I think you're over estimating the mass and value of a restartable engine vs a one time use one. The hypergolic starter fuels that SpaceX uses to relight engines on the F9 1st stage are quite potent and don't weigh very much at all. The engines are designed to be radiatively cooled, making them quite reliable over multiple burns. It is known that engines are the most expensive single components of any large flying machine, so based on that alone, reusing a stage 3 times with 9 engines on it is more profitable than expending 3 stages with 7 engines each. The Falcon 9 is also a very inexpensive rocket to make. ULA and some others that make aluminum rockets form the skin out of thicker metal and then machine the inside of the skin with massive milling machines. This has the effect of making a very strong and lightweight skin, and measurably increases the performance of the rocket, but it contributes to the incredible cost of the rocket. SpaceX on the other hand, uses what amounts to high quality sheet metal to build their rockets, with little to no machining required, other han drilling holes, I presume. This makes the rocket slightly less efficient, but massively reduces build costs. The performance hit is fine, since the F9 design is quite capable, expendable or otherwise, and the cost savings in manufacturing can be passed on to the customer. SpaceX also saves vast sums of money by making most of their stuff in house, instead of subcontracting things to other companies like ULA does. In short, I suspect it costs SpaceX a fair bit less than $50m to make a brand new Falcon 9, and if they can reuse one even once, they can save quite a bit of money by not having to manufacture another one. Combine all this with Gwen Shotwell's claim of significantly less than 50% of manufacturing costs to refurbish the first reuse (they've presumably gotten better after ~35 times) and you have some very significant financial reasons for reusing the first stages. I think the argument that 'SpaceX is losing money therefore reuse of medium rockets isn't worth it' is disingenuous. We don't, and never will, know all the things that SpaceX is spending money on, and if they are indeed losing money, it is not because of the Falcon 9. SpaceX is pushing the boundaries of rocket technology in a remarkable number of directions, and regardless of your opinions of their motives, you can at least give them credit where it's due. Both the Merlin and the Raptor are amazing engines, and you really can't beat the price to performance of them. Whatever other R&D they're crunching in the background might be eating their profits, but I'm certain the Falcon 9 is more than capable of paying it's own way at current pricing. Quote Link to comment Share on other sites More sharing options...
Technical Ben Posted August 21, 2019 Share Posted August 21, 2019 (edited) 38 minutes ago, kerbiloid said: https://space.stackexchange.com/questions/13935/how-does-the-falcon-9-first-stage-avoid-burning-up-on-re-entry [edit] I just realised, that's probably someone commenting who does not know anything, and making it up. The other posts in there are probably right about the speed not being enough for re-entry heat to matter. I do the powered re-entry a little in KSP at times. Edited August 21, 2019 by Technical Ben Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 (edited) 30 minutes ago, Thor Wotansen said: I am 100% certain that reuse of the Falcon 9 first stage is increasing SpaceX's profits. No publicly available data. 30 minutes ago, Thor Wotansen said: I think you're over estimating the mass and value of a restartable engine vs a one time use one. The hypergolic starter fuels that SpaceX uses to relight engines on the F9 1st stage are quite potent and don't weigh very much at all. The engines are designed to be radiatively cooled, making them quite reliable over multiple burns. It is known that engines are the most expensive single components of any large flying machine, so based on that alone, reusing a stage 3 times with 9 engines on it is more profitable than expending 3 stages with 7 engines each. Ok, agreed about the "restartability", it doesn't matter. 30 minutes ago, Thor Wotansen said: The Falcon 9 is also a very inexpensive rocket to make. No publicly available data. 30 minutes ago, Thor Wotansen said: ULA and some others that make aluminum rockets form the skin out of thicker metal and then machine the inside of the skin with massive milling machines. This has the effect of making a very strong and lightweight skin, and measurably increases the performance of the rocket, but it contributes to the incredible cost of the rocket. SpaceX on the other hand, uses what amounts to high quality sheet metal to build their rockets, with little to no machining required, other han drilling holes, I presume. Is it for sure that Space-X uses plain aluminium instead of waffles? It would be a back to 1950s. It sounds very strange. Also their presentation shows some pattern (decorative or not) on the walls. Spoiler 30 minutes ago, Thor Wotansen said: and the cost savings in manufacturing can be passed on to the customer If the cost is lesser than price. No publicly available data. 30 minutes ago, Thor Wotansen said: In short, I suspect it costs SpaceX a fair bit less than $50m to make a brand new Falcon 9, and if they can reuse one even once, they can save quite a bit of money by not having to manufacture another one. As well. 30 minutes ago, Thor Wotansen said: Combine all this with Gwen Shotwell's claim of significantly less than 50% of manufacturing costs to refurbish the first reuse (they've presumably gotten better after ~35 times) and you have some very significant financial reasons for reusing the first stages. Still a PR-based assumption. No publicly available data. Of course, a reused instance of the rocket is cheaper that the same one manufactured again. This doesn't include money spend on the process of its reusage (delivering, testing, etc) and doesn't tell anything about its comparison to its cheaper expendable version. So, this "50%" tells actually nothing. 30 minutes ago, Thor Wotansen said: We don't, and never will, know all the things that SpaceX is spending money on, and if they are indeed losing money It is not about Space-X economy, it is about the quality of the given data. They are so fuzzy that tell actually nothing. 30 minutes ago, Thor Wotansen said: SpaceX is pushing the boundaries of rocket technology in a remarkable number of directions Currently I can see only one: they can land a 1st stage on a barge and launch it twice again. Not that this looks like a progress in remarkable number of directions. Just one more rocket and its landing (they could do this it in Apollo times, and Buran has autolanded on a runway). 30 minutes ago, Thor Wotansen said: Both the Merlin and the Raptor are amazing engines, and you really can't beat the price to performance of them. Yes, two good engines more. 8 minutes ago, Technical Ben said: I just realised, that's probably someone commenting who does not know anything, and making it up. The other posts in there are probably right about the speed not being enough for re-entry heat to matter. I do the powered re-entry a little in KSP at times. In KSP you can't deflect the heat with the engine exhaust, afaik. It has a simplified heating model. Maybe with Deadly Reentry, I'm not aware. Edited August 21, 2019 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Technical Ben Posted August 21, 2019 Share Posted August 21, 2019 1 minute ago, kerbiloid said: In KSP you can't deflect the heat with the engine exhaust, afaik. It has a simplified heating model. Maybe with Deadly Reentry, I'm not aware. Yeah, I meant I slow down a bit using engines. But does the Falcon really use engine power to deflect the atmosphere heating??? Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 (edited) 4 minutes ago, Technical Ben said: But does the Falcon really use engine power to deflect the atmosphere heating??? Quote The exhaust plume from that burn, as well, forces the atmospheric compression that creates reentry heat to occur well away from the rocket. That's the only reason why it does it, afaik. To just land you should ignite them as low as possible. Edited August 21, 2019 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Nothalogh Posted August 21, 2019 Share Posted August 21, 2019 5 minutes ago, Technical Ben said: But does the Falcon really use engine power to deflect the atmosphere heating??? No, it does not, and he has been trying to insinuate that it does for a couple pages now, it's utterly idiotic. The entry burn slows the vehicle enough that shock heating is mitigated before it becomes a concern. Quote Link to comment Share on other sites More sharing options...
tater Posted August 21, 2019 Share Posted August 21, 2019 Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 (edited) @tater, please, could you clarify: does Falcon ignite its engines on re-entry to deflect the air flow or to slow the stage down to make this flow weak? Though, @Nothalogh, this is actually no difference. It spends fuel on reentry, that's what I mean. So needs to take it more. Edited August 21, 2019 by kerbiloid Quote Link to comment Share on other sites More sharing options...
tater Posted August 21, 2019 Share Posted August 21, 2019 7 minutes ago, kerbiloid said: @tater, please, could you clarify: does Falcon ignite its engines on re-entry to deflect the air flow or to slow the stage down to make this flow weak? Why not both? Supersonic retropropulsion works in that way (the exhaust moved the shock front away from the vehicle) (3 engines helps here, as I understand it). But during this process it also simply slows the vehicle such that there's less heating, anyway. Stage 1 booster is pretty slow, you have to remember, stage sep is at ~2.something km/s (usually low 2.something). So even a short 3 engine burn will strip a lot of that velocity off. 7 minutes ago, kerbiloid said: Though, @Nothalogh, this is actually no difference. It spends fuel on reentry, that's what I mean. So needs to take it more. Yes, we know from talks/tweets that for RTLS (Return To Launch Site) they take about a 40% payload to LEO hit, and for ASDS landing, it's more like 18%. Improvements in the Merlins, as well as the move to superchilling has created so much margin that this is not a problem. It's not like anyone is going to fit 23 tons of cargo under a 5m fairing, really huge sats are less than 1/3 that mass, Falcon has loads of excess capability. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 1 minute ago, tater said: Supersonic retropropulsion works in that way (the exhaust moved the shock front away from the vehicle) (3 engines helps here, as I understand it). But during this process it also simply slows the vehicle such that there's less heating, anyway. Stage 1 booster is pretty slow, you have to remember, stage sep is at ~2.something km/s (usually low 2.something). So even a short 3 engine burn will strip a lot of that velocity off. Yes, thank you. That's what I mean, as it has enough low velocity it uses the engines exhaust to form a gasodynamic virtual heatshield instead of a solid one. And obviously this has a side effect of deceleration. Quote Link to comment Share on other sites More sharing options...
tater Posted August 21, 2019 Share Posted August 21, 2019 11 minutes ago, kerbiloid said: Yes, thank you. That's what I mean, as it has enough low velocity it uses the engines exhaust to form a gasodynamic virtual heatshield instead of a solid one. And obviously this has a side effect of deceleration. For S1 entry, I'm not sure which effect dominates, though, since it's already really slow compared to an orbital entry (where a wide propulsive bow shock slows the vehicle more than the propulsion actually does). I'm unsure if F9 has always done a 3 engine entry burn, or if they've experimented with other combinations. Quote Link to comment Share on other sites More sharing options...
Brotoro Posted August 21, 2019 Share Posted August 21, 2019 The entry burn is relatively short, so they can't be counting on the deflecting effect of the exhaust to be the primary effect that keeps the stage from overheating...that only works during the burn. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 21, 2019 Share Posted August 21, 2019 1 minute ago, Brotoro said: The entry burn is relatively short, so they can't be counting on the deflecting effect of the exhaust to be the primary effect that keeps the stage from overheating...that only works during the burn. In sense of fuel spending there is no difference which effect prevails. But I was worrying if I got this wrong, and the re-entry burn isn't used as a deflector. I'm happy if both effects work together. Quote Link to comment Share on other sites More sharing options...
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