JoeSchmuckatelli Posted March 14 Share Posted March 14 Very late to the party - just watched with my students. Why was Booster so much above terminal so deep into the atmosphere? It was supersonic at 5km Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted March 14 Share Posted March 14 2 hours ago, Exoscientist said: If SpaceX wants to prove the Raptor can relight reliably they need to... That's just it -- SpaceX doesn't need to prove anything about their engines, certainly not to forum-goers. They test as they fly. They need to know internally how to meet their performance obligations. That is all they need to prove. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted March 14 Share Posted March 14 (question abt the landing attempt) boost back /reentry looked great until I saw it wasn't slowing down much. Does it rely entirely on the landing burn to slow then stop? Quote Link to comment Share on other sites More sharing options...
AckSed Posted March 14 Share Posted March 14 (edited) 2 minutes ago, JoeSchmuckatelli said: Very late to the party - just watched with my students. Why was Booster so much above terminal so deep into the atmosphere? It was supersonic at 5km. I think it was going for the hoverslam, but the roll oscillation starved the engines and removed the 'hover'. Edited March 14 by AckSed Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted March 14 Share Posted March 14 Just now, sevenperforce said: performance obligations Goals. They have no obligations, just intentions. Ofc you know that. Quote Link to comment Share on other sites More sharing options...
zolotiyeruki Posted March 14 Share Posted March 14 3 hours ago, Exoscientist said: Actually, we do know definitely that the engines did not all relight during the landing burn for the booster. That proves something went wrong at this relight, and the damage could even have occurred during the first relight during boostback except that burn was not long enough to cause loss of vehicle. If something goes wrong with the engines during flight, and it is a known problem to have occurred before during testing the first thing to suspect is that same issue is occurring again. There's an assumption here that a longer boostback burn would/could have caused loss of vehicle. What's your rationale there? Keep in mind that these engines are designed to be reused, so the duration of the burn is pretty irrelevant. The relights for boostback aren't a reasonable analog for relights for a landing burn. They just really aren't comparable. You've typed a lot of words about how SpaceX need to be testing Raptor more before flying them. How do you propose they test the "light the engines while moving backwards at mach 3 at 35,000 feet and decelerating at 5g's" scenario? Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted March 14 Share Posted March 14 Just now, JoeSchmuckatelli said: Very late to the party - just watched with my students. Why was Booster so much above terminal so deep into the atmosphere? It was supersonic at 5km Terminal velocity is the stable point at which gravity and drag are equal, assuming infinite time to slow down or speed up. The booster was falling from space and was still actively decelerating under drag all the way down. Most meteorites don't actually hit the ground with any of the speed they had in space; they reach terminal velocity and then fall under the influence of gravity alone. It's only the really big ones that can punch all the way through the atmosphere while still maintaining some of the original interplanetary velocity. Basically, terminal velocity is reached when the mass of air that has been pushed out of the way by the falling object equals the mass of the object. A meteor that is about 2.4 meters in diameter can reach the ground with interplanetary velocity if it is mostly iron; if it is a rocky meteor then it needs to be closer to 4.4 meters in diameter. Of course that is the size that has to survive ablation. Any meteorite smaller than that will have reached terminal velocity before hitting the ground. 16 minutes ago, JoeSchmuckatelli said: 18 minutes ago, sevenperforce said: performance obligations Goals. They have no obligations, just intentions. Ofc you know that. Well they do have certain performance obligations for their HLS contract with NASA. That's what I was talking about (because that's what a certain someone keeps bringing up, as if a contractual obligation to provide a particular service somehow creates a public interest in HOW they test the components with which they intend to provide that service). Quote Link to comment Share on other sites More sharing options...
tater Posted March 14 Share Posted March 14 (edited) https://www.spacex.com/launches/mission/?missionId=starship-flight-3 Quote Starship returned to integrated flight testing with its third launch from Starbase in Texas. While it didn’t happen in a lab or on a test stand, it was absolutely a test. What we achieved on this flight will provide invaluable data to continue rapidly developing Starship. On March 14, 2024, Starship successfully lifted off at 8:25 a.m. CT from Starbase in Texas and went on to accomplish several major milestones and firsts: For the second time, all 33 Raptor engines on the Super Heavy Booster started up successfully and completed a full-duration burn during ascent. Starship executed its second successful hot-stage separation, powering down all but three of Super Heavy’s Raptor engines and successfully igniting the six second stage Raptor engines before separating the vehicles. Following separation, the Super Heavy booster successfully completed its flip maneuver and completed a full boostback burn to send it towards its splashdown point in the Gulf of Mexico. Super Heavy successfully lit several engines for its first ever landing burn before the vehicle experienced a RUD (that’s SpaceX-speak for “rapid unscheduled disassembly”). The booster’s flight concluded at approximately 462 meters in altitude and just under seven minutes into the mission. Starship's six second stage Raptor engines all started successfully and powered the vehicle to its expected orbit, becoming the first Starship to complete its full-duration ascent burn. While coasting, Starship accomplished several of the flight test’s additional objectives, including the opening and closing of its payload door (aka the pez dispenser,) and initiating a propellant transfer demonstration. Starship did not attempt its planned on-orbit relight of a single Raptor engine due to vehicle roll rates during coast. Results from these demonstrations will come after postflight data review is complete. Starship went on to experience its first ever entry from space, providing valuable data on heating and vehicle control during hypersonic reentry. Live views of entry were made possible by Starlink terminals operating on Starship. The flight test’s conclusion came during entry, with the last telemetry signals received via Starlink from Starship at approximately 49 minutes into the mission. While our team reviews the data collected from this flight, Starship and Super Heavy vehicles are preparing for upcoming flights as we seek to increase our launch cadence throughout the year. This rapid iterative development approach has been the basis for all of SpaceX’s major innovative advancements, including Falcon, Dragon, and Starlink. Recursive improvement is essential as we work to build a fully reusable transportation system capable of carrying both crew and cargo to Earth orbit, help humanity return to the Moon, and ultimately travel to Mars and beyond. Thank you to our customers, Cameron County, spaceflight fans, and the wider community for the continued support and encouragement. And congratulations to the entire SpaceX team on an exciting third flight test of Starship! Looks like I was right. Restart aborted due to roll rate. Edited March 14 by tater Quote Link to comment Share on other sites More sharing options...
Exoscientist Posted March 14 Share Posted March 14 Update from SpaceX. The booster experienced a RUD after the landing relight before contacting the water: "Super Heavy successfully lit several engines for its first ever landing burn before the vehicle experienced a RUD (that’s SpaceX-speak for “rapid unscheduled disassembly”). The booster’s flight concluded at approximately 462 meters in altitude and just under seven minutes into the mission.“ https://www.spacex.com/launches/mission/?missionId=starship-flight-3 So SpaceX still has not demonstrated the Raptor can relight reliably in flight. In fact, all the Starship landing tests and actual flight tests have shown it is not reliable after relight in flight. Bob Clark Quote Link to comment Share on other sites More sharing options...
Pthigrivi Posted March 14 Share Posted March 14 (edited) Nice to have confirmation on the pez door. It wasn't really clear from the video that was working. It says they initiated but didn't complete the fuel transfer which makes sense with lack of control. Tim Dodd speculated the thruster ports might have been affected by ice build up. It'll be interesting to hear more about that. Edited March 14 by Pthigrivi Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 14 Share Posted March 14 4 hours ago, sevenperforce said: Yep, that makes sense. RIP Starship -- you went farther than any before! I'm worried that it could be burn-through at tile loss. I'm also worried because I have no idea how they would figure that sort of thing out. I'm really hoping they have IR cameras aimed at the inside of the belly streaming to Starlink and collecting all kinds of juicy re-entry data Quote Link to comment Share on other sites More sharing options...
Kartoffelkuchen Posted March 14 Share Posted March 14 10 minutes ago, Exoscientist said: [ - snip - ] So SpaceX still has not demonstrated the Raptor can relight reliably in flight. In fact, all the Starship landing tests and actual flight tests have shown it is not reliable after relight in flight. Bob Clark Funny that you say that. Because in the paragraph above your quoted text, it clearly says they conducted a successful boostback burn, and they did so with all engines igniting and running perfectly fine when looking at the webcast. Looking at the final seconds of the booster, with these high roll rates, it is no wonder the engines didn't light succesfully. It's not hard to imagine that when it's rolling like that and fuel sloshing around inside the tanks, that fuel ports won't be able to draw any fuel reliably. And to emphasize again, that is not a Raptor related issue, but more of a fuel systems and a 'how to prevent fuel sloshing' issue. So I'd like to call your "Raptors can't relight successfully" argument fully debunked now with that successful boostback burn, until we a re proven otherwise by SpaceX. Quote Link to comment Share on other sites More sharing options...
tater Posted March 14 Share Posted March 14 Like everyone else I've long since run out of likes. 29 minutes ago, Exoscientist said: So SpaceX still has not demonstrated the Raptor can relight reliably in flight. In fact, all the Starship landing tests and actual flight tests have shown it is not reliable after relight in flight. That's it, I guess they quit for now, and build a billion dollar facility so they can not actually test what you are concerned about. For reasons. It's important to restate the fact that no amount of ground testing would ever replicate this flight regime. Concern trolling doesn't change this. Fuel issues within the tanks in a flight regime are not tested on the ground, ever. Restarting with the engines pointed into the airflow at ~1km/s? Also not possible to test on the ground. The way to test this is to test it the same way they just did. Quote Link to comment Share on other sites More sharing options...
PakledHostage Posted March 14 Share Posted March 14 1 hour ago, sevenperforce said: This may be part of the inherent limitations of "best part is no part" engineering: they might just have to add in a separate thruster system after all. Anyone have any thoughts on Everyday Astronaut's hypothesis that the liquid oxygen was freezing around the cold gas thruster nozzles, partially blocking them and affecting the resulting thrust force and direction sufficiently to screw up the control system? He figured SpaceX may have to add heaters on the nozzles. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted March 14 Share Posted March 14 29 minutes ago, Exoscientist said: SpaceX still has not demonstrated the Raptor can relight reliably in flight. "SpaceX is just a private company; it still has not demonstrated it can launch a liquid-fueled rocket!" "SpaceX can launch a liquid-fueled rocket, but it still has not demonstrated it can reach orbit!" "SpaceX can put a liquid-fueled rocket in orbit, but it still has not demonstrated it can deliver a useful payload!" "SpaceX can deliver useful payloads to orbit, but it still has not demonstrated it will be able to bring a booster back through re-entry!" "SpaceX can bring boosters back through re-entry, but it still has not demonstrated it will be able to land!" "SpaceX can land boosters, but it still has not demonstrated it can refly them!" "SpaceX can land and refly boosters, but it still has not demonstrated economical reflight!" "SpaceX can make booster reflight economical, but it still has not demonstrated a design for a recoverable second stage!" "SpaceX has built a recoverable second stage, but it still has not demonstrated that the engines work!" "SpaceX got Raptor engines working, but it still has not demonstrated that it can land on them!" "SpaceX completed low-altitude hop tests, but it still has not demonstrated relighting the Raptors!" "SpaceX completed high-altitude hop tests with successful Raptor relight, but it still has not demonstrated landing successfully!" "SpaceX completed high-altitude hop tests with landings, but it still has not demonstrated simultaneous firing of enough Raptors for Superheavy!" "SpaceX completed static-fire tests, but it still has not demonstrated it can actually launch without blowing up!" "SpaceX launched without blowing up, but it still has not demonstrated stage separation and in-flight lighting of the second-stage engines!" "SpaceX achieved stage separation and lit the second-stage engines, but it still has not demonstrated Raptor can relight in flight!" "SpaceX achieved Raptor relight in flight, but it still has not demonstrated the Raptor can relight reliably in flight!" See where this is going? 5 minutes ago, PakledHostage said: Anyone have any thoughts on Everyday Astronaut's hypothesis that the liquid oxygen was freezing around the cold gas thruster nozzles, partially blocking them and affecting the resulting thrust force and direction sufficiently to screw up the control system? He figured SpaceX may have to add heaters on the nozzles. That seems like a pretty likely possibility. That's part of the inherent design of cold-gas thrusters. Alternatively they could go to hot gas-gas thrusters. Quote Link to comment Share on other sites More sharing options...
Elthy Posted March 14 Share Posted March 14 1 hour ago, tater said: Super Heavy successfully lit several engines for its first ever landing burn before the vehicle experienced a RUD (that’s SpaceX-speak for “rapid unscheduled disassembly”). The booster’s flight concluded at approximately 462 meters in altitude and just under seven minutes into the mission. Interessting to see that it actualy exploded in the air, not on impact. At those speeds its about 1 second difference, was hard to tell from the video. I hope they will release footage of the booster as its comming down, but im not sure if they have any. Afaik it was out of view from the land, so only a plane could have captured it, right? Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 14 Share Posted March 14 11 minutes ago, sevenperforce said: "SpaceX is just a private company; it still has not demonstrated it can launch a liquid-fueled rocket!" "SpaceX can launch a liquid-fueled rocket, but it still has not demonstrated it can reach orbit!" "SpaceX can put a liquid-fueled rocket in orbit, but it still has not demonstrated it can deliver a useful payload!" "SpaceX can deliver useful payloads to orbit, but it still has not demonstrated it will be able to bring a booster back through re-entry!" "SpaceX can bring boosters back through re-entry, but it still has not demonstrated it will be able to land!" "SpaceX can land boosters, but it still has not demonstrated it can refly them!" "SpaceX can land and refly boosters, but it still has not demonstrated economical reflight!" "SpaceX can make booster reflight economical, but it still has not demonstrated a design for a recoverable second stage!" "SpaceX has built a recoverable second stage, but it still has not demonstrated that the engines work!" "SpaceX got Raptor engines working, but it still has not demonstrated that it can land on them!" "SpaceX completed low-altitude hop tests, but it still has not demonstrated relighting the Raptors!" "SpaceX completed high-altitude hop tests with successful Raptor relight, but it still has not demonstrated landing successfully!" "SpaceX completed high-altitude hop tests with landings, but it still has not demonstrated simultaneous firing of enough Raptors for Superheavy!" "SpaceX completed static-fire tests, but it still has not demonstrated it can actually launch without blowing up!" "SpaceX launched without blowing up, but it still has not demonstrated stage separation and in-flight lighting of the second-stage engines!" "SpaceX achieved stage separation and lit the second-stage engines, but it still has not demonstrated Raptor can relight in flight!" "SpaceX achieved Raptor relight in flight, but it still has not demonstrated the Raptor can relight reliably in flight!" See where this is going? That seems like a pretty likely possibility. That's part of the inherent design of cold-gas thrusters. Alternatively they could go to hot gas-gas thrusters. While it would add complexity, they could circulate heat from engine components into a sink and use that to deice the cold gas thrusters. Maybe Quote Link to comment Share on other sites More sharing options...
Codraroll Posted March 14 Share Posted March 14 I was watching the liftoff in awe, and re-entry quite slack-jawed. That footage of the hypersonic air stream and re-entry plasma in real time was gorgeous. Quite mind-boggling that they were able to broadcast the footage even as the spacecraft was tumbling through the atmosphere in a stream of plasma so bright that the Earth itself wasn't visible next to it. 5 hours ago, tater said: “we are watching the end of SLS” quote from someone at MCC relayed to me That struck me as well. Quite aside from the whole re-entry thing, what Starship just did was to bring more mass to orbit than SLS ever could, at a vastly lower cost than even the side boosters of SLS, and there's a mass production line of these already up and running. It wouldn't take much adaptation of the already proven concepts of Starship to far outperform everything SLS dreams of doing. Even when treated as an expendable two-stage rocket, with all the waste it implies, Starship still does more than SLS does, for less. 5 hours ago, sevenperforce said: It appears that literally anything that does or does not happen during any test will be interpreted by you to support your pet theory about Raptor reliability. I will definitely keep this excellently consise summation of Exoscientist's whole posting history for future use. Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 14 Share Posted March 14 3 minutes ago, Codraroll said: Quite aside from the whole re-entry thing, what Starship just did was to bring more mass to orbit than SLS ever could, at a vastly lower cost than even the side boosters of SLS, and there's a mass production line of these already up and running. It wouldn't take much adaptation of the already proven concepts of Starship to far outperform everything SLS dreams of doing. Even when treated as an expendable two-stage rocket, with all the waste it implies, Starship still does more than SLS does, for less. Imagine a fully streamlined Tesla mega factory sized operation churning these out. That is what Musk imagines, iirc, given what he described in an interview once. New frontier indeed Quote Link to comment Share on other sites More sharing options...
CBase Posted March 14 Share Posted March 14 By all the fancy targets of SpaceX let us not forget what the primary objective of rockets is: delivering a payload to its target orbit. Shown with IFT-3: ✔ Liftoff ✔ 1st stage burn ✔ stage seperation ✔ 2nd stage engine start ✔ 2nd stage burn ❌ control authority during coast phase ? second stage engine relight (some of us might conclude that the capability was demonstrated with 1st stage, few experts on this forum see it as raptors major issue) ✔ payload door opening ? payload seperation / dispense In my personal view they are damn close to having an operational, ultra heavy, orbital class rocket. 5 hours ago, tater said: “we are watching the end of SLS” quote from someone at MCC relayed to me So true. Just like Falcon 9 all the fancy reuse stuff will come as they use it for delivering payload and start to get return on investment. Quote Link to comment Share on other sites More sharing options...
AckSed Posted March 14 Share Posted March 14 If they don't crack relight soon, 150 tons leaves room for a hell of a boost stage. In fact, the F9 second stage would be perfect. Quote Link to comment Share on other sites More sharing options...
Terwin Posted March 14 Share Posted March 14 It seems reasonable that SpaceX may include starlinks as payload on attempts 4+ They may wait until 5, but loading 4 seems plausible Quote Link to comment Share on other sites More sharing options...
PakledHostage Posted March 14 Share Posted March 14 2 minutes ago, Terwin said: It seems reasonable that SpaceX may include starlinks as payload on attempts 4+ They may wait until 5, but loading 4 seems plausible That's hard to find reasonable... Starship hasn't reached orbit yet, and it seemingly hasn't maintained attitude control in zero-g, either. Who would put a non-expendable payload on it before it's been proven more capable? (Maybe some Star Trek red shirted crew want to go for a ride?) Quote Link to comment Share on other sites More sharing options...
Brotoro Posted March 14 Share Posted March 14 (edited) Maybe they need an entry burn (like Falcon 9) to take some (entry) heat off the raptors, and allow them to relight at a lower oncoming dynamic pressure. But I don't have access to the engine telemetry like SpaceX does, so they will know a lot more about this. But the booster was clearly all jinky before relight, so whatever is causing that needs to be dealt with (since it may be the cause of their difficulties). Edited March 14 by Brotoro Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 14 Share Posted March 14 3 minutes ago, Terwin said: It seems reasonable that SpaceX may include starlinks as payload on attempts 4+ They may wait until 5, but loading 4 seems plausible On a vaguely related note, I was pondering if the change to ditching in the Indian Ocean may have had something to do with being in the same orbital plane as a v2 Starlink sat with a good view up the plasma skirt Quote Link to comment Share on other sites More sharing options...
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