deepbluecea.bsky.social @deepbluecea.bsky.social · 14hThird, because the BE-4 is MUCH heavier than Raptor v3 (for the same amount of thrust), adding 80kg of heat exchanger per BE-4 (for 7 engines) barely makes a dent. For a lightweight Raptor, and with 33 of them, it's far more impactful. 700
deepbluecea.bsky.social @deepbluecea.bsky.social · 14hFirst, because with only 7 (or 9) engines, New Glenn is far more sensitive to an engine-out (due to ice) than Super Heavy with 33 engines. Second, New Glenn has far more room in the skirt to add plumbing for heat exchangers; Super Heavy is too densely packed to easily do this. 300
deepbluecea.bsky.social @deepbluecea.bsky.social · 15hTo clarify, by "mesh size" I meant total mesh area, not the size of the individual holes in it. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 05/10/2026OMG. Math is theoretical. Engineering is applied. Materials do not behave perfectly according to equations. Engineering uses math as an approximation and starting point, but saying that engineering IS math is just ludicrously upside-down. Engineering is about the difference between math and reality. 110
deepbluecea.bsky.social @deepbluecea.bsky.social · 05/10/2026It mentions FFSC and describes how extraordinarily complex it is. (So complex that no one had ever flown it, and it was considered impractical by the industry.) It mentions supersonic retropropulsion and how destabilizing it is. (Until SpaceX engineered their way through that barrier.) And so on. 410
deepbluecea.bsky.social @deepbluecea.bsky.social · 05/10/2026100kg PER ENGINE. The Starship booster has 33 engines. That's 3300kg. For the ice filters, the "several hundred kilograms" IS the frame. The mesh weighs practically nothing. (An order of magnitude less than the frame.) First principles analysis of the fluid flow rate reveals the expected mesh size. 210
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026Of course not. I mentioned them to address your comment that "Just one split seam and that piece of crap rocket is instant space junk." Space junk cannot perform a controlled deorbit burn, but Starship with a split seam could. 000
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026On the RS-25 or BE-4, the heat exchanger plumbing adds 70-100kg per engine. Extrapolating to 33 engines on Super Heavy, that's ~3 tons. The mesh filters in the tank are several hundred kilograms. So SpaceX's approach is ~5x more mass-efficient. 110
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026Sutton is theory, not engineering. SpaceX has taken many of the elements that Sutton had described for years as impractical (e.g. FFSC, rockets landing on their tails), and made them practical. In theory, theory and practice are the same. In practice, they're not. 210
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026Starship also has nitrogen COPV's and cold-gas thrusters, and the deorbit burn is performed from the header tanks. So even in a worst case scenario where the ullage thrusters / OMS stop working, Starship would still be able to orient itself and perform a controlled deorbit burn. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026Those heat exchangers add a lot of mass and complexity, much more than the mesh filters do. Rocketry is about choosing the right compromises and tradeoffs. Highly unlikely that the engine failures on ascent were due to ice. Both Ship and Booster use header tanks for the landing burn anyway. 410
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026Not too fine a point on it, but SpaceX got to where they are today by ignoring the gold standard in rocketry textbooks, which said that supersonic retropropulsion was impossible, among other things. 110
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026The RCS/OMS uses (or can use) the header tanks, which are isolated and independent from the main tanks. Losing main tank pressure wouldn't remove control authority. They are not idiots. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 04/10/2026It's tapped off from the preburner, so still about 97% pure O2. SpaceX decided that it's better to save 4 tons of plumbing and complexity on the engines and replace it with 1 ton of mesh filters inside the tanks. If they turn out to be wrong, they can modify some of the Raptors to provide pure O2. 400
deepbluecea.bsky.social @deepbluecea.bsky.social · 03/10/2026Robustness to engine-outs is an integral part of Starship's design; 33 engines to MECO is not required. Deorbiting early out of an abundance of caution is standard test-flight discipline, not a loss of capability. (The deorbit went just fine, and of course the payload was deployed successfully.) 210
deepbluecea.bsky.social @deepbluecea.bsky.social · 03/10/2026But yes, obviously autogenous pressurization is stubbornly stupid, because Blue Origin (New Glenn) and ULA (Vulcan booster stage) also use it. What do you know that SpaceX, Blue Origin, and ULA are all missing? 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 03/10/2026?? Both Super Heavy and Starship completed textbook-perfect landing maneuvers and splashdown on Flight 14, even with two engines out on the Booster, a much better result than Flight 13, which indicates that whatever the problem is, they're making significant progress solving it. 211
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Interesting question: what would they do if the Booster lost say 8 engines on ascent? It might still be able to get Ship to orbit by burning longer and sacrificing its own RTLS; conversely, it's possible that both vehicles could immediately RTLS, if there were two catch towers available. 000
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Yes, the booster is designed to be robust to 3-5 engine-outs on ascent, and Ship can lose 1, depending on the timing. (Losing 2 late in ascent would be ok, as long as they're not both sea-level: at least 2 sea-level engines are needed for safety/redundancy for the deorbit burn and landing burn.) 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Yes, with 600kg of payload. The Apollo architecture would be completely unworkable for Artemis. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026With LH2, sure. But no rocket has ever carried or used LH2 for more than a few hours after launch, because it's so difficult to store and keep cold. Blue Origin is taking a huge leap by choosing it for their Lunar architecture. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026They have RCS already. Their OMS thrusters haven't flown in space yet, but have been ground-tested at McGregor, and the v3 hulls have attachment points for them. Missions to date haven't needed them. I think they have enough experience with OMS on Dragon that they can get this working. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026NRHO to the Lunar surface and back to NRHO is about 5,600m/s. I'd call that a "large change in delta-V" (technically a change in V). Using 300s engines for that entire burn (in Starship's case), at any thrust level, would result in negative payload capacity. That's why the Raptors are essential. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Did I use the word 'thrust' in my previous reply? I did not. You're imagining things. Obviously thrust and ISP are independent. Efficiency and ISP are not. Raptor's efficiency is what makes it hugely advantageous for the bulk of the mission. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Given where they currently are (after Flight 14), what do you think is the biggest blocker to getting there? I'd give them 40% odds of landing a Starship successfully on the Moon by 2029, 70% by 2030. 95% by 2035, barring any black swan events. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026It has to do with how much payload you can efficiently get there (and back) from LLO/NRHO. RVac is 380s. Apollo's Lunar stages were around 300s. Most of Starship HLS's descent will be 1g or greater, but chairs (if needed) are tiny relative to the payload capacity. The final 100m will be very slow. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026To clarify, Starship cargo missions are expected to take 100-150 metric tons of payload each, with the Ship staying on the Moon. For a roundtrip mission where the Ship must launch back to NRHO afterward, the practical payload is more like 15-25 metric tons. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026They're not grossly overpowered if you're trying to decelerate 100 metric tons of payload from NRHO to the Lunar surface. (Apollo could do, what, 600kg?) They're overpowered for the last 100 meters, sure, but for everything above that, Raptor's ISP makes it the far better choice. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Raptors will bring the rocket to a near-hover 100m off the Moon's surface. From there, the thrust required to counteract Lunar gravity is quite low, and distributed among many small thrusters. (Obviously the ring will be braced.) To decrease thrust, they can shut some off, not just deep-throttle. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Disaster? That's a bit strong. The entire flight was nominal enough that the FAA is not even requiring a mishap investigation, which they tend to do at the drop of a hat. 110
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Starship will not use its high-powered Raptors for the final phase of descent. It will use a ring of many lower-powered thrusters mounted high on the vehicle. It's a completely different design (obviously) from Apollo's landers, and works around the throttle problem in a completely different way. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026For the exceptionally rare cases where your different statistic is more important, that would make a single 200T launch worth 50x more than two 100T launches, Starship can simply fly expendable. (E.g. launching the seed cable for a space elevator.) What am I missing? 000
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026The point being, the worst-case landing impact velocity (to 3 sigma) will be significantly less severe than it would be on Earth. It's still the largest force the legs have to absorb, but still smaller (at 3 sigma) than it would be on Earth for similar terrain. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026First principles. The approach on the Moon involves much less thrust than equivalent approach on Earth, thus far less near-instantaneous change in thrust when the engines are cut, and less delta-V cost to approaching the landing more gradually, so more fine control over the touchdown velocity. 300
deepbluecea.bsky.social @deepbluecea.bsky.social · 30/09/2026Sure. Still, the legs could be 2-3x lighter than would be required for equivalent landing legs on Earth. It can all be done as structural additions to the baseline skirt design, not reinventing it from scratch. No one has more experience with rocket landing legs than SpaceX. 300
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026They haven't assembled the final HLS rocket yet, but they've done a ton of work (including plenty of mockups and prototypes, to achieve NASA milestones) on the components and subsystems. It's delayed from the original schedule, but sure, everything in aerospace is always delayed. 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026In any case, even fully expendable, it's already more cost-effective per Tb/s for Starlink launches than partially-reusable Falcon 9 was. I'm sure they'll nail the Raptor 3 reliability; this is only their third flight with these engines. 000
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026The landing burns were successful (both vehicles could have been caught), despite the engine-outs. The early reentry was done only out of an abundance of caution; once the failure mode is understood, the same event on a future flight likely wouldn't cut the mission short or prevent reusability. 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026Where is your SSTO spaceplane that you promised for 2027? 110
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026That is hilarious. I thought he was just an internet troll. 220
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026Nothing. A few tons of stainless steel at the bottom of the ocean is harmless to the environment. (It's occasionally even put there intentionally for artificial reefs.) 010
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026You do realize that this water landing/splashdown was an FAA REQUIREMENT for SpaceX to demonstrate their vehicle's orbital reentry and landing sequence over water first, to gain FAA permission to flyover the US on upcoming missions to land at their landing site (and not explode) at Starbase, TX? 000
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026None. Starship uses Methalox, not hydrazine. The fireball turned any remaining propellant into CO2 and water vapor. 120
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026Maximizing per-launch payload to orbit is not the sole objective. Starship can trivially double the payload to orbit per launch by flying in an expendable configuration, but it costs 100x more per launch to do that, so why would they? 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026And you know precisely how far they are along internally because how? 200
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026The legs will be on the outside of the skirt, not the inside. By the way, helpful tip: do you know that you can get 7 extra characters in your online posts if you omit 'dumbass' or 'dipshit'? 100
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026It will be the same, with a bit of added reinforcement to connect the landing leg loads to the thrust puck. SpaceX is expert at zeroing descent velocity for touchdown, and Lunar gravity is just 1/6 G, so the loads are not huge. The retracted legs will be on the outside of the skirt, not the inside. 101
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026Ah, so that's why SpaceX cleverly named it "Starship HLS", to emphasize that it has nothing whatsoever to do with Starship, except for identical main engines, propellants, tanks, fuselage, booster stage, avionics, comms, and propellant transfer docking ports. Gotcha. 410
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026Starship IS the lander. Starship IS HLS (with relatively minor modifications). Take a Starship, omit the heatshield and flaps, add a crew compartment, hatches, elevator, and some high-mounted thrusters, and that's HLS. 110
deepbluecea.bsky.social @deepbluecea.bsky.social · 29/09/2026By refueling in orbit, a single Starship (HLS variant) will be able to land 100 tons on the Moon. Apollo's payload to the Moon was about 50x less than this, and far more expensive. 110
