Timeline for Why have SpaceX skipped the SpaceX Starship SN12, SN13, and SN14?
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12 events
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| Apr 25, 2021 at 0:23 | comment | added | SafeFastExpressive | But at ground level XRS only 64% & Raptor is 72%. XRS launch ISP only 339 using LH2, barely more than Raptor's 330 from Methane, while XRS also imposes the much heavier tanks that LH2 requires. So it seems far more effective to use the base Raptor for launch, and switch to Vacuum Raptors as the atmosphere thins. You save significant mass on engines and tanks, have no efficiency losses in Mach 1-3 regime, and have a fuel less prone to boil-off on long journeys. There is no useful space mission that requires Aerospikes to be able to be performed. | |
| Apr 25, 2021 at 0:10 | comment | added | SafeFastExpressive | Raptors are designed to land on Earth, and Vacuum Raptors on Mars. You don't need Aerospikes which have always suffered fromf poor thrust to weight ratios, and poor efficiency in low (1-3) Mach realms. The XRS-2200 had a 35-1 ratio, with a production goal of increasing that to 80-1 at a similar thrust to Raptor. Even if it had met those audacious goals it still meant that using two Raptors, ground level and vacuum versions, would mass less and offer higher performance. For comparison, the XRS-2200 & Vacuum Raptor are both at 83% of theoretical max efficiency in space | |
| Apr 14, 2021 at 17:41 | comment | added | Birkensox | There is no reason to think that multistage engines originally designed to launch nuclear warheads in a fast one way trajectory would be also be capable of launching and landing heavy SSTO spaceships. New engines specifically designed for that (eg. aerospike) are required. | |
| Apr 12, 2021 at 23:54 | comment | added | Barry Jenakuns | SN-15 very likely has landing legs as SN-16 does. I'm of the opinion that they won't be attempting catching the SN's until after they're consistently getting through reentry and have very accurate landing profiles. We don't want expendable launch towers. Also gunna have to ask for a citation for BN2 and 3 being designed to be caught instead of using landing legs. | |
| Apr 12, 2021 at 23:42 | comment | added | uhoh | This is really interesting! In the past it was asked How much bigger could Earth be, before rockets wouldn't work?, a new question could be "How much bigger could rockets be, before reuse from Earth wouldn't work?" See also Why SpaceX want to land the rocket on the ground? | |
| Apr 12, 2021 at 23:18 | history | edited | Birkensox | CC BY-SA 4.0 |
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| Apr 12, 2021 at 23:11 | history | edited | Birkensox | CC BY-SA 4.0 |
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| Apr 12, 2021 at 23:05 | history | edited | Birkensox | CC BY-SA 4.0 |
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| Apr 12, 2021 at 22:57 | history | edited | Birkensox | CC BY-SA 4.0 |
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| Apr 12, 2021 at 22:50 | history | edited | Birkensox | CC BY-SA 4.0 |
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| Apr 12, 2021 at 22:48 | review | First posts | |||
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| Apr 12, 2021 at 22:43 | history | answered | Birkensox | CC BY-SA 4.0 |