tater Posted December 31, 2023 Share Posted December 31, 2023 (edited) 6 hours ago, Exoscientist said: What I mean to say is it is standard industry practice to do full thrust, full up(all engines), full flight duration(full length of an actual mission) static firings to flight qualify a rocket stage: That's not a rocket stage. Raptors have had many such tests. 6 hours ago, Exoscientist said: The fact the SH/SS keeps exploding in flight is evidence the SpaceX little 5 second burns are insufficient to qualify the Raptor for flight. Everyone acknowledges the engines on the N-1 were insufficiently tested. The elephant in the room everyone is ignoring is the same is true of the Raptor. The 33 engines on SH performed perfectly on IFT-2. The failure was after the stage had done it's primary job, and was a failure that could not possibly have been found on a ground test (unless you are suggesting a sort of stand that allows the vehicle to somehow flip). So the only concern is the ship. Presumably SpaceX has data that random guys on a game forum don't. Edited December 31, 2023 by tater Quote Link to comment Share on other sites More sharing options...
Flavio hc16 Posted December 31, 2023 Share Posted December 31, 2023 1 hour ago, Exoscientist said: The Saturn V development program resulted in spectacular successes. The Soviet N-1 program resulted in spectacular failures. Robert Clark People who say this are ignorant of the amount of F1 that went kaboom on the stand, especially when they were doing all up testing Quote Link to comment Share on other sites More sharing options...
tater Posted December 31, 2023 Share Posted December 31, 2023 F-1 had a lot of combustion instability issues and a bunch of engine explosions in testing for a couple years, but I don't think they had any catastrophic failures once on a vehicle stage (even in testing). Quote Link to comment Share on other sites More sharing options...
tater Posted December 31, 2023 Share Posted December 31, 2023 Cool shots of boostback Quote Link to comment Share on other sites More sharing options...
darthgently Posted December 31, 2023 Share Posted December 31, 2023 (edited) 1 hour ago, tater said: F-1 had a lot of combustion instability issues and a bunch of engine explosions in testing for a couple years, but I don't think they had any catastrophic failures once on a vehicle stage (even in testing). From what I gathered the F1 engines were each one offs given the amount of unique hand tuning and machining each received to get each one working. They were far more unique working prototypes put into service than products from an assembly line. I read a thread awhile back based on the question "why not just build more F1 engines?" and the answer boiled down to the fact that the people who knew in detail what it took to get the on paper designs to actually function took their secrets to the grave in large part. Combustion instability in such large chambers was a huge problem and each engine had its own hand tuned solution, among other finicky tunings Edited December 31, 2023 by darthgently Quote Link to comment Share on other sites More sharing options...
RCgothic Posted December 31, 2023 Share Posted December 31, 2023 Also we just don't do things the same way anymore even where the production drawings are explicit. We wouldn't braze a load of individual cooling pipes for instance, and would have a very hard time following any drawings calling for that. We'd 3d machine instead. Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted December 31, 2023 Share Posted December 31, 2023 (edited) 15 hours ago, tater said: F-1 had a lot of combustion instability issues and a bunch of engine explosions in testing for a couple years, but I don't think they had any catastrophic failures once on a vehicle stage (even in testing). F-1 did have a serious issue on one of the unmanned Apollo missions. They had recurring issues with "pogo" instability of the middle engine getting into resonance with the vibrational mode of the rocket structure. The fuel would slosh in the feed lines, driving a thrust instability. This would resonate with the structure that supported the middle engine. This was as much a structural issue as an engine issue. It got really bad on one mission (Apollo 6, IIRC), and would have done mission-critical damage if that had been an actual lunar attempt. They solved it for the first stage by injecting helium into the fuel system that damped the slosh. Then on Apollo 13 they had a second-stage early engine shutdown for the same reason ("pogo" of the middle engine), and they had to fix that for later missions too. Edited January 1 by mikegarrison Quote Link to comment Share on other sites More sharing options...
Meecrob Posted January 1 Share Posted January 1 (edited) I imagine ECM's have come a long way in the 50 odd years since Apollo though. I'd imagine modern digital flight control can handle a mid 60's problem. Edit, Just like VSV's, VBV's et al on modern turbofans. Engine technology, and especially engine control technology was in the stone age back then. There is no way a modern engine control infrastructure would not be able to sense pogo oscillations and adjust the pumps as required. You don't see modern airliners stalling their compressors all over the place like 1967, do you lol? (Its an analogy, I am aware, pogo oscillations are not the same as compressor stalls, however they are both a symptom of an engine control loop that cannot operate quickly enough to prevent both bad outcomes. IE an analogue computer. Or just in case analogue computers are technically fast enough, the specific analogue computers used in aerospace are used for their reliability qualities/power requirements, not necessarily the sheer processing ability.) It would be nice if people could hold back on the wild speculations in between Starship flights. Just because it does not meet your personal expectations does not mean it is a failure. Sorry, ban me, whatever, but it needs to be said. Edited January 1 by Meecrob Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted January 1 Share Posted January 1 2 hours ago, Meecrob said: I imagine ECM's have come a long way in the 50 odd years since Apollo though. I'd imagine modern digital flight control can handle a mid 60's problem. It's actually very difficult to tame coupled resonances like that, and mostly control systems just make sure that the engines transit through the danger zones rather than dwell there long enough for the resonance to set up. Quote Link to comment Share on other sites More sharing options...
tater Posted January 1 Share Posted January 1 8 hours ago, Meecrob said: It would be nice if people could hold back on the wild speculations in between Starship flights. We'll have another one to discuss soon enough I hope. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted January 1 Share Posted January 1 11 hours ago, mikegarrison said: It's actually very difficult to tame coupled resonances like that, and mostly control systems just make sure that the engines transit through the danger zones rather than dwell there long enough for the resonance to set up. Yes, this can even be an problems on ships, solution is to not cruise a that speed / engine rpm, just pass it and run at an higher speed. The problem is then the resonance happen at useful velocities like intended cruise speed or flank speed for an warship. Quote Link to comment Share on other sites More sharing options...
SunlitZelkova Posted January 2 Share Posted January 2 On 12/31/2023 at 12:27 AM, Exoscientist said: The fact the SH/SS keeps exploding in flight is evidence the SpaceX little 5 second burns are insufficient to qualify the Raptor for flight. Everyone acknowledges the engines on the N-1 were insufficiently tested. The elephant in the room everyone is ignoring is the same is true of the Raptor. https://twitter.com/RGregoryClark/status/1700872620604891324/photo/ Bob Clark But Starship isn't "certified for flight". It is in the testing phase. There is no issue with explosions right now because these are development flights. What do you propose for correcting Starship? Ground tests? Cancellation? Quote Link to comment Share on other sites More sharing options...
Hotel26 Posted January 2 Share Posted January 2 (edited) On 1/2/2024 at 3:43 PM, SunlitZelkova said: Cancellation? Of course, what is crossing my mind right now, regarding this ongoing discussion, is that it may be time for full disclosure by all parties engaged, about stock holdings IRL. Just, you know... to know. Yeah? @Exoscientist? Edited January 7 by Hotel26 Quote Link to comment Share on other sites More sharing options...
tater Posted January 2 Share Posted January 2 Quote Link to comment Share on other sites More sharing options...
RCgothic Posted January 2 Share Posted January 2 So that's 98 launches total? So close! Quote Link to comment Share on other sites More sharing options...
Flavio hc16 Posted January 2 Share Posted January 2 1 hour ago, RCgothic said: So that's 98 launches total? So close! Yeap, the weather screw them over in the 1dt half of December. But it's still an insane result. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted January 2 Share Posted January 2 2 hours ago, RCgothic said: So that's 98 launches total? So close! If you count each core launched, five FH launches makes 15 cores launched, for a total of 106 Falcon cores launched… Quote Link to comment Share on other sites More sharing options...
Geonovast Posted January 3 Share Posted January 3 2 hours ago, StrandedonEarth said: If you count each core launched, five FH launches makes 15 cores launched, for a total of 106 Falcon cores launched… It's still just one launch for three cores. Would a Delta IV heavy count as three? Now, if you wanna count a Falcon Heavy as one launch and two landings, I would be on board with that. Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted January 3 Share Posted January 3 (edited) 18 hours ago, Hotel26 said: Of course, what is crossing my mind right now, regarding this ongoing discussion, is that it may be time for full disclosure by all parties engaged, about stock holdings IRL. Just, you know... to know. Yeah? @Exoscientist? I don't know what you are talking about here. SpaceX is a private company, not a public one, so they don't have public shareholders they have to make disclosures to. If you are alluding to some sort of self-dealing or other financial games, that can still be an issue with private companies. If you mean that the mostly anonymous posters on this board need to reveal if they have a financial interest in the companies being discussed, that's ridiculous. I mean, so what if they do? This isn't journalism; this is a forum for a computer game. Edited January 3 by mikegarrison Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted January 3 Share Posted January 3 I mean uh, I have like 50 bucks in a Robinhood account I made during COVID and nearly forgot about. I have $3.52 in fractional Tesla stock, so I guess I am a Musk shill. Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted January 3 Share Posted January 3 I actually sold my directly-owned Boeing stock after I retired, but still have some in my 401K. There. Now you know. So did that change anyone's lives? Quote Link to comment Share on other sites More sharing options...
SunlitZelkova Posted January 3 Share Posted January 3 27 minutes ago, mikegarrison said: I don't know what you are talking about here. SpaceX is a private company, not a public one, so they don't have public shareholders they have to make disclosures to. If you are alluding to some sort of self-dealing or other financial games, that can still be an issue with private companies. If you mean that the mostly anonymous posters on this board need to reveal if they have a financial interest in the companies being discussed, that's ridiculous. I mean, so what if they do? This isn't journalism; this is a forum for a computer game. I'm pretty sure @Hotel26 was saying this in jest. Quote Link to comment Share on other sites More sharing options...
tater Posted January 3 Share Posted January 3 music Quote Link to comment Share on other sites More sharing options...
Hotel26 Posted January 3 Share Posted January 3 (edited) On 1/3/2024 at 10:41 AM, SunlitZelkova said: I'm pretty sure @Hotel26 was saying this in jest. "Top of the class, SZ!" It wasn't the SpaceX boosters, I was joking about, either... Edited January 7 by Hotel26 Quote Link to comment Share on other sites More sharing options...
tater Posted January 3 Share Posted January 3 260th F9 landing. Nominal orbit Quote Link to comment Share on other sites More sharing options...
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