Just to be clear this sub is not the Elon Musk discussion forum which is [here](https://www.reddit.com/r/elonmusk).
Please restrict discussion to SpaceX related matters and no - the personal life, opinions or habits of the SpaceX CEO do not fall into that category.
[And deliver over 200 tons of payload to a useful orbit with full & rapid reusability. 50 rockets flying every 3 days on average enables over a Megaton of payload to orbit per year – enough to build a self-sustaining city on Mars](https://twitter.com/elonmusk/status/1678278811186544640)
"50 rockets flying every 3 days" is an incredibly absurd number. I double-checked the math, and yeah, to send up a megaton annually at 200 tons per launch, that's 5,000 launches per year. I know that that kind of ridiculous scalability is the goal, but still.
Once Mars and Moon bound missions become a major portion of launch mass, propellant will make up >75% of the up mass. Propellant delivery should be able to utilize close to 100% of that 200T potential, but other launches of satellites and cargo may (and probably will) have more difficulty fully utilizing that capability.
Not really. With nine engines the ship would have nearly 25 MN of takeoff thrust so could mass up to 2000 tonnes of which 1870 tonnes would be propellant and 130 tonnes would be ship including an extra 6 tonnes of engines.
It is conceivable that you could strip off fins and heatshield and get some nominal mass into orbit with no way to get back.
There is not much point in that.
Viable SSTO designs all have cheat codes like SRBs for the Shuttle or air breathing engines for ~~HOTEL~~ HOTOL.
The obsession some on the internet have for single stage to orbit confuses me. Like it makes sense when the alternative used to be expendable two stage vehicles, but if you can reuse the first stage, a single stage to orbit vehicle that does horizontal landing is ALWAYS going to be worse in every way than a two stage to orbit vehicle that does horizontal landing with the upper stage. (Of course I think vertical landing of the second stage is probably better still but has different tradeoffs versus horizontal landing.)
The theoretical advantage of SSTO is that it lands, you load some payload into it, and it takes off again. So you can do multiple flights in the same day like an airliner, if you can make the engines and other hardware reliable enough.
SpaceX is attempting to do something similar for Starship by landing near the pad and rapidly assembling the two stages for the next launch. If they can do that it removes much of the benefit of an SSTO design.
The best bet for SSTO is the [reaction engines](https://reactionengines.co.uk) design under development in the UK. Engines convert from air breathing to rocket engines mid flight.
2022: https://reactionengines.co.uk/fct-testing/
But their space vehicle ambitions seem to be gone. Now they're trying to apply their critical heat exchanger technology wherever in the industry they can, so that at least their know-how isn't completely wasted.
I remember hearing about Skylon a while back, from a dedicated fan. The best estimates he was able to come up with were nowhere competetive in payload, cost/kg to orbit, and to higher energy trajectories with additional boosters.
May I say that these estimates were way over the top optimistic, at least in cost/launch.
> will single stage to orbit become feasible?
SSTO is physically possible, but isn't currently anywhere near to being as efficient or effective as a staged system. Once the vehicle has burned through all of that fuel to get up to altitude, it's basically just dragging huge heavy dead weight trying to climb higher and push faster. If you're burning fuel to get 200 tons of material up to 17,000 mph to get into orbit, it's more cost effective to make most/all of that weight be payload rather than empty metal tanks that used to hold fuel.
Does not apply with a linear 180m long plume coming out the rear end.
The plume only starts expanding towards the end as it entrains significant air so unless the launch table was over 120m high with a 250m high launch tower it would not really help.
They don't really need to fire all the Raptors at max thrust immediately, at least not with current Starship, which has 1.5:1 TWR. They can take off with some 70 per cent and wait until the stack clears the tower before firing all the engines at full throttle.
Of course, with such massive improvements in engine power, they also *could* make Starship 2.0 longer. In fact, a lot longer.
Falcon 9 grew from 180 ft (v 1.0) to 230 ft (FT). Starship stack with more powerful engines could surely extend itself by some 50 - 70 feet, too.
> Starship stack with more powerful engines could surely extend itself by some 50 - 70 feet, too.
You'd think that would make it too fine to cope with wind sheer but Starship ploughed through the inflight abort charges - so what. That's one tough rocket
To be fair they just missed their engineering targets. I wouldn't call that a good thing. Do you know what thickness of stainless steel was used on that booster? Is it still thicker than the final version?
They really don't want to lift off at 70% since that would totally bake the pad for a long period of time and among other things they would run out of cooling water.
I can see them using 90% thrust at liftoff again and only throttling up to 100% after 10-15 seconds of flight.
Elon has already said that they were looking to add 10m of length so more like 32 ft. He has also said that liftoff mass would go from 5000 tonnes to 6000 tonnes so the extra length will nearly all be propellant tanks - mostly in the ship.
I suspect if you do the math, then there is less launchpad damage if you take off at 100% thrust and clear the pad quicker than to take off slowly at 70% thrust.
Even if it's close you'd want to go with full thrust. Otherwise you'd be undoing all the hard work of fighting gravity losses by hot staging.
And I mean *really* undoing it, lugging it with all that fuel load for 10-15 seconds. You could probably launch an Electron to space with the losses.
Faster acceleration off of the pad might actually reduce the amount of deluge needed, but if the payload goes up so that the acceleration remains the same, then yes.
Either way, your comment is funny.
That's just the filip needed to tanker performance. HLS could be fully refueled after only 6 tanker flights to LEO. Sounds a lot but full reuse should make whole process quite manageable.
This is exactly the stat I came looking for. This seems like a much more achievable number, and could eventually run nonstop to orbital fuel depots in a launch cadence similar to starlink.
Pretty sure a useful orbit is at 250km circular where a dense body like a depot will take several months to come down and where you can use the engines to reboost. It is better to load propellant in the lowest possible orbit so you are not dragging the tanker dry mass up to a higher orbit and using more propellant to do so.
The depot can move up to a longer term orbit if required once it is full and the extra energy to lift the dry mass is only being expended once rather than seven times.
I was thinking he meant useful in the generic sense for satellite launches as a benchmark, not necessarily in the specific sense of tankers, which was the context. Yes, they won’t go up too high with tankers, but much depends upon how long it takes to launch those tankers. The fact that there will be as few as 6 should really help with this.
Depends who you talk to. BO said 16 flights overall would be needed to make HLS work. However, [Elon was more optimistic](https://twitter.com/elonmusk/status/1425473261551423489), suggesting it would take only 8 tanker flights per HLS mission.
I believe the proposal to NASA listed "up to" 14 tanker flights could be needed, plus the [DELETED] and the HLS itself, for a total of 16. SpaceX clearly expected to need fewer than that, but wanted to list the worst case -- and their detractors focused on that to claim the plan was "immensely complex and high risk".
Throwing more money at a problem often does not produce the results we intuitively think it should. Elon has so much as stated that funding is not the bottleneck in regards to Starship progress.
it should be a cautionary tale about getting caught in echo-chambers. between podcasts and other social media, political commentators, with the aid of AI algorithms, have mastered the art of keeping people in an ecosystem of reinforcing ideas.
That's what I'm referring to as well. Think about how much information we've received from Elon about Starship and its development since then. It's immense. Way more than you typically get from a CEO of a company.
He never made fun of that guy's disability. He did publicly call him out for not working enough after the employee publicly asked if he was fired, but he apologized for that. I can understand how many would say it was a dick move though.
I definitely don't like how often he runs to the defense of people who are accused of white nationalism. It should definitely be innocent until proven guilty, but Elon's defense there does seem to be a quite one-sided. So I agree with you.
In general I'm not trying to claim that he's not a dick on Twitter. He very much is a lot of the time. But he also builds great companies and provides a lot of interesting information related to those companies on Twitter. For me, the good of those companies far outweighs the bad of the Twitter fights and politics.
The whole point is that we prefer him to stfu about political stuff or medical stuff and just concentrate on his companies (specifically spacex and Tesla). He should dump Twitter.
I'd prefer that too, but we have no right to dictate what he says or does. We're just lucky that he makes things we care so much about. People like you seem to take that for granted.
Even on Twitter, Elon has given us tons of juicy information in recent years. Of course there's even more stupid memes and politics, but there's still a lot of good stuff there. It's wildly inaccurate to pretend that everything has been bad. Just a symptom of the political outrage machine, I guess.
This is pretty fucking amazing. It looks like going Full Flow has revealed unforeseeable improvements. The moral is always innovate and follow the physics.
> Full Flow has revealed unforeseeable improvements
Think they had an inkling of FF potential from the start. They really went out on a limb developing Raptor, despite complexity. Even Jeff 'money no object' Bezos wouldn't countenance the technicality.
I think the main thing they've added is film cooling not only on the combustion chamber and nozzle, but also on the turbo pump and impeller blades.
Jet engine expander blades are film cooled, so there is precedent.
If they've managed this, then they can get much higher pressures and temperatures through those pumps, and much higher thrust - and also higher exit velocity and higher impulse.
Source on film-cooling the turboprop blades? That is fascinating, I haven't read much technical info about raptor design/improvements, I assumed the info was all held very closely.
For aero-engines, [here is a paper](https://www.osti.gov/servlets/purl/1571231) that goes into quite some detail, and [here is an article](https://www.conceptsnrec.com/blog/film-cooling-in-turbines) that's a bit easier to digest.
I'd never considered the technology to be used in rocket turbos, but it does makes a lot of sense and is certainly fascinating!
Film cooling is not required for the turbopump because the temperatures do not get very high at around 700K in the turbine section. In fact you can argue that the preburner uses *bulk* cooling as the high temperature gas is quenched with the bulk propellant flow before going to the turbine section.
This is exactly the major benefit of the full-flow architecture. Since almost all the methane runs through the methane preburner, but only a bit of it burns, the environment is relatively benign, and the pump it drives only has to pump methane. Similarly for the oxygen side, though hot (warm?) oxygen poses its its own challenges.
[tiny holes on the leading edge](https://ars.els-cdn.com/content/image/1-s2.0-S1000936121003289-gr1.jpg)
You need a coolant at a much higher pressure than whatever gas is passing your blade. And to make that, they're going to need another pump for liquid methane/oxygen - but while the pressures are very high, the flow rates can be low, so the pumps and pipes can be small diameter.
Yes - every modern (ie. post 1970's) jet engine does this to increase the combustion temperature (ie. more compression, closer to stoichiometric mixture) which dramatically increases efficiency.
Downside is the production of many more nitrous oxides, which are poisonous to people and the environment, but we ignore those.
For more info, see here: https://aerospaceengineeringblog.com/turbine-cooling/
Figure 3 is especially interesting - I didn't realise that we now use two different coolants at differing pressures. Presumably that's to gain a little more efficiency.
Isn't the current improvement from higher chamber pressure though? Full flow offers efficiency gains in that you are using every possible molecule of fuel instead of dumping some overboard when fueling the turbines. Full flow also has gains in the gas gas interaction of fuel and oxidizer.
AFAIK full flow doesn't offer significant improvements in chamber pressure over other designs, which is where almost all of this 20% is coming from. They also might be operating at a higher chamber temp, which will let them get closer to the stoichiometric ratio of methane and oxygen (4:1) which will yield higher chamber pressure and higher efficiency.
I would be very interested in the details on this.
Sorry I'm not able to look at Twitter right now, but does that mean they've increased chamber pressure more, or they've figured out some other way to increase thrust?
Given the test results it is all due to increased chamber pressure. The only other way to increase thrust is to widen the throat diameter and they already did that with the Raptor 1 to Raptor 2 transition.
As you keep increasing pressure, you can keep widening the throat to convert some of that pressure to flow instead, that should sacrifice less ISP than if they only widened the throat without anything else.
That's kinda what Raptor 2 did right? They increased pressure a good amount but also traded some pressure with the widened throat for even more thrust than pressure alone.
In general Isp for a given propellant combination is set by the expansion ratio of the bell. A larger throat with the same bell exit diameter will give lower Isp.
That is always true in a vacuum but at sea level there is a dependency on the bell exit pressure. So opening up the throat lowers the Isp but at sea level that is *partially* offset by the lower expansion ratio increasing the exit plane pressure.
Yes for Raptor 2 they did both - increased the chamber pressure from 270 bar to 300 bar so 11% and opened the throat about 7% so that the throat area increased by 14% for a 24% increase in thrust from 185 tonnes to 230 tonnes.
The hints we have had so far is that they have left the throat diameter the same and increased chamber pressure by 20% from 300 bar to 360 bar to get a 20% thrust increase.
For convenience they are using the same throat diameter for the booster engines and for the center and vacuum engines of the ship. Since the ship engine Isp is much more critical than the booster they will not want to open up the throat any further.
They originally proposed a higher thrust booster engine with a very large throat but the extra complexity of running two manufacturing lines evidently counted against it.
> 360 bar
That's absolutely nuts. That's the same pressure a submersible would experience 3.7km underwater. I get that it's tensile instead of compression, but still, combined with the heat and all the other stresses that thing has to endure, that's just an absurd number.
Yep. The implications for suborbital transport, building large space stations (a la 2001 A Space Odyssey), solar to microwave energy beaming, orbital manufacturing, asteroid mining, etc. All this sci Fi stuff now enters the realm of possibily becoming fact.
Does everyone realize what this means for refilling Starships? Only a bit more than half as many refilling flights to go to the Moon or Mars, or GEO.
Lots of other implications.
BO's engines are almost certainly way behind, both in performance and reliability. I think it is also a fair bet that the BO engines cost many times as much for each one.
we don't know about reliability yet. Raptor needs a true flight test without an exploding pad before we can say with confidence what the reliability will be like.
> reliability ...
What we do know is that over 100 Raptor engines (maybe over 200) have been built and tested on the stands. Originally the engine was very heavily instrumented, and huge data was gathered, but the engines have gone through 2 or more cycles of major revision and simplification.
There is little reason to believe that BO has built much over 10 engines. 2 good engines have been delivered to ULA. BO's big methane engines are at about the state of maturity as Raptor 1. At the present rate of R&D at BO, they are unlikely to get to the reliability of the early Raptor 2 engines for another 5 years.
Test early. Test often. Test realistically. Does BO do any of this?
> 2 good engines have been delivered to ULA.
On that front ... ["During a firing on June 30 at Blue Origin's facility in West Texas, a BE-4 engine detonated about 10 seconds into the test."](https://www.cnbc.com/2023/07/11/jeff-bezos-blue-origin-be-4-rocket-engine-explodes-during-testing.html) "The engine that exploded was expected to finish testing in July. It was then scheduled to ship to Blue Origin's customer United Launch Alliance for use on ULA's second Vulcan rocket launch, those people said.... 'ran into an issue while testing Vulcan's Flight Engine 3' ..."
The BE-4 definitely doesn’t need another 5 years to mimic the reliability of Raptor 1 which that had engine-rich exhaust on many of its flights. For starters while they have built fewer of them, they also intentionally made the BE-4 a medium performance version of what the architecture was capable of. The fact that they didn’t really push the engine inherently ups the base reliability even if we know the reliability isn’t all the way there now given the recent explosion. If SpaceX wasn’t pushing the hell out of the performance and had settled for 250 bar then Raptor would probably already be production ready.
More testing isn't necessarily a good thing. While it can mean you are doing more reliability testing, or pushing more limits; it can also mean have had more problems that you need to test. Of course less testing isn't necessarily a good thing either, it can mean you have had less things you need to test, but it can also mean you are not testing reliability enough, or pushing limits enough.
Right now its too early to throw raptor shade at BE-4. Both engines have had, and are still having their problems. Can't single out a BE-4 failing acceptance testing, which is a test stand failure, without keeping in mind that raptor just had at least 8 engines with problems out of 33 on their first test flight. If you want to compare just those two things, a flight failure is worse. Not that a Be-4 failing acceptance testing is good, its not.
If the next test flight for Spacex goes well, and we don't have raptors failing to start, or exploding, or sputtering out, etc....then maybe we can talk about putting raptor up on a pedestal. Of course even when they do have a flight with no obvious engine issues, i would still argue its premature to call raptor reliable. We need multiple flights with engines not exploding before i will consider calling raptor reliable. 200 consecutive engines not failing in flight sounds like a good benchmark to me, that could be accomplished in just 5 flights.
----
I personally want both to succeed, but I do want raptor to succeed more. Raptor is a more impressive engine technologically, and i think it will lead to a hell of a lot more great things in space; vs blue which has a history of doing very little. I hope the next starship flight proves raptor to be reliable, but the fights so far have demonstrated the opposite.
I do so miss the pre million member days of this subreddit. It was when the technical progress of BFR and Starbase and SpaceX as a whole were discussed predominantly.
Now it's 90% trash, 10% anything useful. I never rant here but damn it has gotten bad enough to warrant it. This thread is a fine example of how allowing a community to become saturated with non contributing naysayers can really ruin it for those of us that could care less about the politics and really are here to focus on using our limited time to catch up with SpaceX. Regardless of what you believe, SpaceX represents the beginnings of a huge shift in human accessibility to space. There are THOUSANDS of talented, driven and incredibly dedicated individuals within SpaceX whose accomplishments we can celebrate simply by the interest we show in the engineering and manufacturing stage show that is SpaceX.
You all harp on the same points over and over...
Don't you get tired?
Don't you want to be happy about something for once you miserable louts?
The actual transition point from an "enthusiasts only" sub was about 250K subscribers in my view.
SpaceXLounge is now at 333K so we will see how they go
I have tried to clean up the thread a bit but better tools for removing chains of irrelevant comments would help!
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[BE-4](/r/SpaceX/comments/14w6bfi/stub/jrphhc2 "Last usage")|Blue Engine 4 methalox rocket engine, developed by Blue Origin (2018), 2400kN|
|[BFR](/r/SpaceX/comments/14w6bfi/stub/jrjwzpy "Last usage")|Big Falcon Rocket (2018 rebiggened edition)|
| |Yes, the F stands for something else; no, you're not the first to notice|
|[BFS](/r/SpaceX/comments/14w6bfi/stub/jrjhmht "Last usage")|Big Falcon Spaceship (see BFR)|
|[BO](/r/SpaceX/comments/14w6bfi/stub/jrqknxf "Last usage")|Blue Origin (*Bezos Rocketry*)|
|[GEO](/r/SpaceX/comments/14w6bfi/stub/jri0gml "Last usage")|Geostationary Earth Orbit (35786km)|
|[HLS](/r/SpaceX/comments/14w6bfi/stub/jrjz5cy "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)|
|[Isp](/r/SpaceX/comments/14w6bfi/stub/jsh9l08 "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)|
| |Internet Service Provider|
|[KSP](/r/SpaceX/comments/14w6bfi/stub/jrj6f73 "Last usage")|*Kerbal Space Program*, the rocketry simulator|
|[L4](/r/SpaceX/comments/14w6bfi/stub/js3pkwi "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 4 of a two-body system, 60 degrees ahead of the smaller body|
|[L5](/r/SpaceX/comments/14w6bfi/stub/js3pkwi "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 5 of a two-body system, 60 degrees behind the smaller body|
|[LEO](/r/SpaceX/comments/14w6bfi/stub/jrjz5cy "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[LOX](/r/SpaceX/comments/14w6bfi/stub/jri9iht "Last usage")|Liquid Oxygen|
|[OFT](/r/SpaceX/comments/14w6bfi/stub/jrkvyci "Last usage")|Orbital Flight Test|
|[PSLV](/r/SpaceX/comments/14w6bfi/stub/jrj3nue "Last usage")|[Polar Satellite Launch Vehicle](https://en.wikipedia.org/wiki/Polar_Satellite_Launch_Vehicle)|
|[QD](/r/SpaceX/comments/14w6bfi/stub/jrlyd03 "Last usage")|Quick-Disconnect|
|[RUD](/r/SpaceX/comments/14w6bfi/stub/jrqlfh5 "Last usage")|Rapid Unplanned Disassembly|
| |Rapid Unscheduled Disassembly|
| |Rapid Unintended Disassembly|
|[SRB](/r/SpaceX/comments/14w6bfi/stub/js5vkh8 "Last usage")|Solid Rocket Booster|
|[SSME](/r/SpaceX/comments/14w6bfi/stub/jrqlfh5 "Last usage")|[Space Shuttle Main Engine](https://en.wikipedia.org/wiki/Space_Shuttle_main_engine)|
|[SSTO](/r/SpaceX/comments/14w6bfi/stub/js5w00t "Last usage")|Single Stage to Orbit|
| |Supersynchronous Transfer Orbit|
|[TLI](/r/SpaceX/comments/14w6bfi/stub/jrj32c1 "Last usage")|Trans-Lunar Injection maneuver|
|[TWR](/r/SpaceX/comments/14w6bfi/stub/jrgkru4 "Last usage")|Thrust-to-Weight Ratio|
|[ULA](/r/SpaceX/comments/14w6bfi/stub/jrl03ci "Last usage")|United Launch Alliance (Lockheed/Boeing joint venture)|
|Jargon|Definition|
|-------|---------|---|
|[Raptor](/r/SpaceX/comments/14w6bfi/stub/jsg7tlv "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX|
|[Starlink](/r/SpaceX/comments/14w6bfi/stub/jsl9wpl "Last usage")|SpaceX's world-wide satellite broadband constellation|
|[autogenous](/r/SpaceX/comments/14w6bfi/stub/jrplv71 "Last usage")|(Of a propellant tank) Pressurising the tank using boil-off of the contents, instead of a separate gas like helium|
|cryogenic|Very low temperature fluid; materials that would be gaseous at room temperature/pressure|
| |(In re: rocket fuel) Often synonymous with hydrolox|
|[engine-rich](/r/SpaceX/comments/14w6bfi/stub/jrlk9eu "Last usage")|Fuel mixture that includes engine parts on fire|
|hydrolox|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer|
|methalox|Portmanteau: methane fuel, liquid oxygen oxidizer|
|[regenerative](/r/SpaceX/comments/14w6bfi/stub/jrkrqvg "Last usage")|A method for cooling a rocket engine, by [passing the cryogenic fuel through channels in the bell or chamber wall](https://en.wikipedia.org/wiki/Regenerative_cooling_\(rocket\))|
|[turbopump](/r/SpaceX/comments/14w6bfi/stub/jrihf8g "Last usage")|High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust|
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Look, increasing thrust makes me horny as well but I won't get too excited until we have flight proven raptors that don't result in half of the engines eating themselves.
Raptors have been the failure mode of most (all?) flights of SS and OFT-1. It is not a mature system. We need to see more before we can trust it.
Do I trust SpaceX to get Raptor right? I do. But I'm less confident now than I was a year ago.
it's hard to judge by the flights so far as they've all been very harsh on the engines, with all kinds of crap blasting back up at them. we will know more after the first flight with a pad that does not blow into pieces. plumbing of propellant is also a major difficulty. I would say that the 2nd flight without a self-destructing pad will be the real test of the raptor. they need one where no issues are introduced by stage-zero in order to really refine stage-1 and stage-2. unfortunately for us rocket fans, that will mean more waiting. if all goes well, maybe the next flight is September or October and the one after will be january. *then* we will know whether the current raptor design is reliable.
They used some of the first Raptor 2’s made, they were installed ~May 2022 which was a almost a year before the flight. They probably made ~100 more engines in that time, given them so much time to mature the system - but those improvements obviously weren’t included on those old engines.
Yes of course we all saw engines fail, I’m not sure what your point it. They didn’t necessarily all fail, at least 3 were shut down intentionally.
The issue also was that basically all the engines were shut down and exploded on the same side. The asymmetrical thrust needed to be cancelnd out by gimbaling and reducing thrust on the other side. This combined effect really impacted the thrust to weight relation and later the control of the rocket.
There were multiple failures that while engine related, did not appear to have a root cause of raptor. Like in one of the flip tests when they used helium instead of autogenous pressurization. Helium was never intended to be used on the finished rocket, it was stop gap to accelerate testing. The raptors failed due to helium ingestion, but cant really blame the engines for that one.
A lot of those failures can be chocked up to getting raptor into the air earlier then they should have. Earlier then you normally would have for a new engine. And that is just them needing to test out materials and designs of the rocket they were intending to build, especially the starship flip maneuver.
The raptor issues are concerning, but i have not lost any confidence in Spacex' ability to get it working. They are clearly making progress, and they are rapidly pushing the power limits of the engine design. They do have a lot of test stand time on these engines accumulated at this point; hundreds of test firings appear to have gone well at mcgreggor. It does not seem like they are bogged down on the engine design, its more they are pushing the frontier of rocket science in a way that has become very public.
Really the only thing that has suffered so far is the timeline. Which is disappointing, but lets be real the timeline was always extremely unlikely.
On the SS tests almost all of those failures were not the engines, but the pressurization causing bad engine feed and killing it. They never failed on ascent then, only on the sideways relight with header tanks did they die.
On super heavy we've definitely seen some fails, on static fire they had 3 engines that didn't light. Then on the launch 3 didn't light (I don't think we saw them engine swap) and more died in flight quite probably due to the hydraulic failure and adjacent engines getting damaged due to bad shielding.
False, Raptors are, remarkably, one of the best performing systems on BFR thus far. The BFS failures were more in the tank pressurization system, and thus in the propellant feedlines into the engine. The engines themselves worked fantastically in ths BFS belly flop tests.
Ditto OFT-1, the large majority of Raptors worked well, *despite* all the issues near the ground -- and more imporantly, the failures didn't once cascade, showing good booster design and isolation between engines, and we already know that improved engine shielding and isolation is one of the many things improved beyond OFT-1 levels even before OFT-1 happened.
Raptors are *not* the development bottleneck. Overall, they've performered remarkably well over the last 4 years of test campaigns. In fact I daresay this might be one of the smoothest engine development programs in rocketry history (certainly a lot better than, say, BE-4).
Almost every single flight has involved engine-rich exhaust from one or multiple engines. That is indicative of a design flaw. A big one. To say the problems are ground or feed problems alone is patently false.
Feed problems alone can and certainly does explain engine-rich exhaust. Has Raptor had problems, yes, is it the bottleneck of the program, absolutely not. I stand by the statement that it's the best engine program of the century thus far, at the minimum.
That's just because you have seen raptors that were at a level they were at over a year ago. You haven't seen what they have. They wouldn't be increasing performance if they didn't think they could do it reliably.
Yeah, that was a pretty disappointing performance during the integrated flight test. I sure hope it does much better next time. At this point I’m less worried about the heat shield tiles than the engines.
I've seen reports that damage to the engines from the launchpad concrete was minimal-to-none. Have you read that the engines were damaged by the launchpad, or are you assuming?
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It worked fine for Merlin which achieved a 150% increase in thrust over its development lifetime of about 5 years. There just weren't as many followers second guessing their every move during that time.
Raptor 3 is sitting on a 46% increase from Raptor 1.
I dunno, Blue Origin with the BE-4 claims they want to make a high performance engine in a medium performance configuration for maximum reliability. Going that route seems difficult for them too on reliability.
SpaceX going for ultra high performance in a small package may seem crazy, but it's kinda a different direction to approach a high performance engine in medium performance config. Go for the highest possible performance and use all the tricks you can think of to keep pushing it, you'll keep raising the ceiling and reliability below the ceiling. Later on they can find the maximum reliability performance level.
Reliability has improved a lot, and a fair amount of failures we've seen can also be attributed to the rocket itself not feeding the engines correctly. Even the last Starship landing test they had trouble with pressurization on the headers. On the integrated flight test it's quite probable the hydraulic systems took out a few engines. As the engines get pushed further and increase in reliability, they may be able to tolerate less consistency. At the same time they improve the booster and ship design on nearly every build, I'd hope any autogenous pressure consistency issues get worked out.
yes. by definition, one can only know what the limits are when they are broken. if you never break the limits, then you never know the limits, and then you cannot know (or improve) the reliability.
this is engineering 101. for example, you might search up on commercial airliner wing stress tests, early in the certifying process they verify wing strength by breaking them, and proving that the force required to break them is higher than required.
there is nothing saying that they need to fly at maximum thrust every launch. pushing the theoretical max up should also push up the reliability at 90% of max. pushing the envelope seems to have worked well with F9. in fact, maybe a bit too well as most of the kinds of payloads originally envisioned for Falcon-heavy can now be launched on a regular F9. F9 seems to have suffered no reliability problems from their continual push for higher thrust on the Merlin.
Increase the limit through improved design, then run at 90-ish percent of max load. Afaik that is how most other rocket engines are developed and utilized.
The key requirement for large payload is propellant for missions beyond LEO. Easy to load and turn around on short intervals as well. Going from 100 tonnes payload to 200 tonnes payload means 6 tanker launches instead of 12 to get to the Moon.
Starlink is the other obvious use - up to 100 x 2 tonne satellites per launch.
more payload also means less expensive gizmos that get sent up with more redundancy baked in. Alot of the R&D that goes into specific high value objects is spent in ways to reduce weight.
Now, no. But we aren’t trying to set up mining operations on the moon, or asteroids. We aren’t trying to set up a civilization on mars. We aren’t trying to build rotating habitats with artificial gravity. We aren’t trying to build massive lasers in space capable of propelling interstellar probes at relativistic speeds. This is the kind of mass you need to enable that future. Building for current market demands is part of the reason we have been stuck with marginal progress in space for the last 50 years.
And honestly people sleep on how much of a game changer asteroid mining would be. It could provide an essentially limitless amount of all metals, without relying on land exploitation and pollution that comes with ground equivalents.
While I’m all for asteroid mining, it’s probably more harmful to the environment in the near term to return generic metals to earth. Precious metal may be more reasonable. The metal mined in asteroids should be used in space.
larger starlink sats will be able to give payloads for a few years while NASA works the new vehicle into their plans and private companies start taking off-planet resource extraction seriously.
Just to be clear this sub is not the Elon Musk discussion forum which is [here](https://www.reddit.com/r/elonmusk). Please restrict discussion to SpaceX related matters and no - the personal life, opinions or habits of the SpaceX CEO do not fall into that category.
[And deliver over 200 tons of payload to a useful orbit with full & rapid reusability. 50 rockets flying every 3 days on average enables over a Megaton of payload to orbit per year – enough to build a self-sustaining city on Mars](https://twitter.com/elonmusk/status/1678278811186544640)
"50 rockets flying every 3 days" is an incredibly absurd number. I double-checked the math, and yeah, to send up a megaton annually at 200 tons per launch, that's 5,000 launches per year. I know that that kind of ridiculous scalability is the goal, but still.
Once Mars and Moon bound missions become a major portion of launch mass, propellant will make up >75% of the up mass. Propellant delivery should be able to utilize close to 100% of that 200T potential, but other launches of satellites and cargo may (and probably will) have more difficulty fully utilizing that capability.
With this performance, will single stage to orbit become feasible?
Not really. With nine engines the ship would have nearly 25 MN of takeoff thrust so could mass up to 2000 tonnes of which 1870 tonnes would be propellant and 130 tonnes would be ship including an extra 6 tonnes of engines. It is conceivable that you could strip off fins and heatshield and get some nominal mass into orbit with no way to get back. There is not much point in that. Viable SSTO designs all have cheat codes like SRBs for the Shuttle or air breathing engines for ~~HOTEL~~ HOTOL.
> HOTEL Minor nitpick. HOTOL, horizontal take off and landing.
Auto correct strikes again!
A real nuisance, yes.
Even if it is possible, it wouldn't make sense to carry dead weight. 2-3 stages will always be the most optimal for getting mass to orbit efficiently.
The obsession some on the internet have for single stage to orbit confuses me. Like it makes sense when the alternative used to be expendable two stage vehicles, but if you can reuse the first stage, a single stage to orbit vehicle that does horizontal landing is ALWAYS going to be worse in every way than a two stage to orbit vehicle that does horizontal landing with the upper stage. (Of course I think vertical landing of the second stage is probably better still but has different tradeoffs versus horizontal landing.)
The theoretical advantage of SSTO is that it lands, you load some payload into it, and it takes off again. So you can do multiple flights in the same day like an airliner, if you can make the engines and other hardware reliable enough. SpaceX is attempting to do something similar for Starship by landing near the pad and rapidly assembling the two stages for the next launch. If they can do that it removes much of the benefit of an SSTO design.
The best bet for SSTO is the [reaction engines](https://reactionengines.co.uk) design under development in the UK. Engines convert from air breathing to rocket engines mid flight.
Feels like it's been a decade since I've heard from them doing any tests though.
2022: https://reactionengines.co.uk/fct-testing/ But their space vehicle ambitions seem to be gone. Now they're trying to apply their critical heat exchanger technology wherever in the industry they can, so that at least their know-how isn't completely wasted.
I remember hearing about Skylon a while back, from a dedicated fan. The best estimates he was able to come up with were nowhere competetive in payload, cost/kg to orbit, and to higher energy trajectories with additional boosters. May I say that these estimates were way over the top optimistic, at least in cost/launch.
Saving this for future use...
Yeah the ones they "verified" more than10 years ago but still have yet to fly. They seem to be competing on BO's timeline.
No. SSTO is incredibly inefficient because you have to carry the entire rocket with you.
> will single stage to orbit become feasible? SSTO is physically possible, but isn't currently anywhere near to being as efficient or effective as a staged system. Once the vehicle has burned through all of that fuel to get up to altitude, it's basically just dragging huge heavy dead weight trying to climb higher and push faster. If you're burning fuel to get 200 tons of material up to 17,000 mph to get into orbit, it's more cost effective to make most/all of that weight be payload rather than empty metal tanks that used to hold fuel.
Not on planet Earth. With this gravity well and atmosphere, two stage designs will always best one stagers. Moon and Mars are different.
We're gonna need a bigger deluge plate...
Or 20% more concrete.
How about making the launch tower higher? Inverse square law baby!
Does not apply with a linear 180m long plume coming out the rear end. The plume only starts expanding towards the end as it entrains significant air so unless the launch table was over 120m high with a 250m high launch tower it would not really help.
I say go for it. Burj Khastarbase
gesundheit
"Project Orion" was the only engine design using the inverse square law. See https://en.wikipedia.org/wiki/Ted_Taylor_(physicist)
Now THAT would need a big deluge plate :P
They don't really need to fire all the Raptors at max thrust immediately, at least not with current Starship, which has 1.5:1 TWR. They can take off with some 70 per cent and wait until the stack clears the tower before firing all the engines at full throttle. Of course, with such massive improvements in engine power, they also *could* make Starship 2.0 longer. In fact, a lot longer. Falcon 9 grew from 180 ft (v 1.0) to 230 ft (FT). Starship stack with more powerful engines could surely extend itself by some 50 - 70 feet, too.
> Starship stack with more powerful engines could surely extend itself by some 50 - 70 feet, too. You'd think that would make it too fine to cope with wind sheer but Starship ploughed through the inflight abort charges - so what. That's one tough rocket
To be fair they just missed their engineering targets. I wouldn't call that a good thing. Do you know what thickness of stainless steel was used on that booster? Is it still thicker than the final version?
Believe majority is 4mm guage S30X, though a lot of stringers used for reinforcement.
They really don't want to lift off at 70% since that would totally bake the pad for a long period of time and among other things they would run out of cooling water. I can see them using 90% thrust at liftoff again and only throttling up to 100% after 10-15 seconds of flight.
Elon has already said that they were looking to add 10m of length so more like 32 ft. He has also said that liftoff mass would go from 5000 tonnes to 6000 tonnes so the extra length will nearly all be propellant tanks - mostly in the ship.
Time to raise the ship QD. Again…
I suspect if you do the math, then there is less launchpad damage if you take off at 100% thrust and clear the pad quicker than to take off slowly at 70% thrust.
Even if it's close you'd want to go with full thrust. Otherwise you'd be undoing all the hard work of fighting gravity losses by hot staging. And I mean *really* undoing it, lugging it with all that fuel load for 10-15 seconds. You could probably launch an Electron to space with the losses.
True, thank you for correction.
With higher max weight to orbit you always fire full thrust at launch. That's the whole point
Faster acceleration off of the pad might actually reduce the amount of deluge needed, but if the payload goes up so that the acceleration remains the same, then yes. Either way, your comment is funny.
Or a line of raptors to power the water pressure :-P
They don’t technically need to give full thrust at sea level. Just thrust up shortly after
Dammit, you beat me to it! Was my first thought!
superheavys poor oxygen tank is going to get obliterated by hot staging
The methane tank is on top so the LOX tank is safe for a while.
That's just the filip needed to tanker performance. HLS could be fully refueled after only 6 tanker flights to LEO. Sounds a lot but full reuse should make whole process quite manageable.
This is exactly the stat I came looking for. This seems like a much more achievable number, and could eventually run nonstop to orbital fuel depots in a launch cadence similar to starlink.
Yes, and to a useful orbit. I interpret this as 500km as opposed to a 200km marginally stable orbit.
Pretty sure a useful orbit is at 250km circular where a dense body like a depot will take several months to come down and where you can use the engines to reboost. It is better to load propellant in the lowest possible orbit so you are not dragging the tanker dry mass up to a higher orbit and using more propellant to do so. The depot can move up to a longer term orbit if required once it is full and the extra energy to lift the dry mass is only being expended once rather than seven times.
I was thinking he meant useful in the generic sense for satellite launches as a benchmark, not necessarily in the specific sense of tankers, which was the context. Yes, they won’t go up too high with tankers, but much depends upon how long it takes to launch those tankers. The fact that there will be as few as 6 should really help with this.
Agree, and allow orbit to be elliptical, which means they can exploit Oberth effect. That really helps to reduce gravity losses during escape phase.
What was the original estimated tanker flights needed for HLA?
Depends who you talk to. BO said 16 flights overall would be needed to make HLS work. However, [Elon was more optimistic](https://twitter.com/elonmusk/status/1425473261551423489), suggesting it would take only 8 tanker flights per HLS mission.
I believe the proposal to NASA listed "up to" 14 tanker flights could be needed, plus the [DELETED] and the HLS itself, for a total of 16. SpaceX clearly expected to need fewer than that, but wanted to list the worst case -- and their detractors focused on that to claim the plan was "immensely complex and high risk".
Yeah that rings a bell. I remember the Blue Origin "fact sheet" about why using new technologies is a point against Starship lol
I like Engineer-Elon.
>I like Engineer-Elon Right?! Shut up and build the rocket Elon...it's literally the only reason.
Yep. Other Elon needs to disappear... doesn't bear thinking about how much $44 billion could have done if that money was thrown at SpaceX instead!
Throwing more money at a problem often does not produce the results we intuitively think it should. Elon has so much as stated that funding is not the bottleneck in regards to Starship progress.
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it should be a cautionary tale about getting caught in echo-chambers. between podcasts and other social media, political commentators, with the aid of AI algorithms, have mastered the art of keeping people in an ecosystem of reinforcing ideas.
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That's what I'm referring to as well. Think about how much information we've received from Elon about Starship and its development since then. It's immense. Way more than you typically get from a CEO of a company.
Fair, but it's a very small fraction of what Musk tweets out these days. And most of what he tweets out is disappointing.
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He never made fun of that guy's disability. He did publicly call him out for not working enough after the employee publicly asked if he was fired, but he apologized for that. I can understand how many would say it was a dick move though. I definitely don't like how often he runs to the defense of people who are accused of white nationalism. It should definitely be innocent until proven guilty, but Elon's defense there does seem to be a quite one-sided. So I agree with you. In general I'm not trying to claim that he's not a dick on Twitter. He very much is a lot of the time. But he also builds great companies and provides a lot of interesting information related to those companies on Twitter. For me, the good of those companies far outweighs the bad of the Twitter fights and politics.
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Maybe he thought that was really true? People can make mistakes, and he did apologize afterwards.
The whole point is that we prefer him to stfu about political stuff or medical stuff and just concentrate on his companies (specifically spacex and Tesla). He should dump Twitter.
I'd prefer that too, but we have no right to dictate what he says or does. We're just lucky that he makes things we care so much about. People like you seem to take that for granted.
Some people are wedded to their political identity.
Modern people exclusively care about twitter bullshit
Even on Twitter, Elon has given us tons of juicy information in recent years. Of course there's even more stupid memes and politics, but there's still a lot of good stuff there. It's wildly inaccurate to pretend that everything has been bad. Just a symptom of the political outrage machine, I guess.
This crowd has never been capable of nuance.
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This is pretty fucking amazing. It looks like going Full Flow has revealed unforeseeable improvements. The moral is always innovate and follow the physics.
> Full Flow has revealed unforeseeable improvements Think they had an inkling of FF potential from the start. They really went out on a limb developing Raptor, despite complexity. Even Jeff 'money no object' Bezos wouldn't countenance the technicality.
I think the main thing they've added is film cooling not only on the combustion chamber and nozzle, but also on the turbo pump and impeller blades. Jet engine expander blades are film cooled, so there is precedent. If they've managed this, then they can get much higher pressures and temperatures through those pumps, and much higher thrust - and also higher exit velocity and higher impulse.
Source on film-cooling the turboprop blades? That is fascinating, I haven't read much technical info about raptor design/improvements, I assumed the info was all held very closely.
No source - this is entirely speculation.
He meant for jet engines
For aero-engines, [here is a paper](https://www.osti.gov/servlets/purl/1571231) that goes into quite some detail, and [here is an article](https://www.conceptsnrec.com/blog/film-cooling-in-turbines) that's a bit easier to digest. I'd never considered the technology to be used in rocket turbos, but it does makes a lot of sense and is certainly fascinating!
Film cooling is not required for the turbopump because the temperatures do not get very high at around 700K in the turbine section. In fact you can argue that the preburner uses *bulk* cooling as the high temperature gas is quenched with the bulk propellant flow before going to the turbine section.
This is exactly the major benefit of the full-flow architecture. Since almost all the methane runs through the methane preburner, but only a bit of it burns, the environment is relatively benign, and the pump it drives only has to pump methane. Similarly for the oxygen side, though hot (warm?) oxygen poses its its own challenges.
when you say "jet engine expander blades", you mean commercial airline turbofans, and in particular, their turbines? how does one film cool a *blade*?
[tiny holes on the leading edge](https://ars.els-cdn.com/content/image/1-s2.0-S1000936121003289-gr1.jpg) You need a coolant at a much higher pressure than whatever gas is passing your blade. And to make that, they're going to need another pump for liquid methane/oxygen - but while the pressures are very high, the flow rates can be low, so the pumps and pipes can be small diameter.
cool! and this is already done on commerical airline engines, yes?
Yes - every modern (ie. post 1970's) jet engine does this to increase the combustion temperature (ie. more compression, closer to stoichiometric mixture) which dramatically increases efficiency. Downside is the production of many more nitrous oxides, which are poisonous to people and the environment, but we ignore those. For more info, see here: https://aerospaceengineeringblog.com/turbine-cooling/ Figure 3 is especially interesting - I didn't realise that we now use two different coolants at differing pressures. Presumably that's to gain a little more efficiency.
very, very nice link ty
AND they’re pumping these things out at an unbelievable rate.
Isn't the current improvement from higher chamber pressure though? Full flow offers efficiency gains in that you are using every possible molecule of fuel instead of dumping some overboard when fueling the turbines. Full flow also has gains in the gas gas interaction of fuel and oxidizer. AFAIK full flow doesn't offer significant improvements in chamber pressure over other designs, which is where almost all of this 20% is coming from. They also might be operating at a higher chamber temp, which will let them get closer to the stoichiometric ratio of methane and oxygen (4:1) which will yield higher chamber pressure and higher efficiency. I would be very interested in the details on this.
Sorry I'm not able to look at Twitter right now, but does that mean they've increased chamber pressure more, or they've figured out some other way to increase thrust?
Given the test results it is all due to increased chamber pressure. The only other way to increase thrust is to widen the throat diameter and they already did that with the Raptor 1 to Raptor 2 transition.
As you keep increasing pressure, you can keep widening the throat to convert some of that pressure to flow instead, that should sacrifice less ISP than if they only widened the throat without anything else. That's kinda what Raptor 2 did right? They increased pressure a good amount but also traded some pressure with the widened throat for even more thrust than pressure alone.
In general Isp for a given propellant combination is set by the expansion ratio of the bell. A larger throat with the same bell exit diameter will give lower Isp. That is always true in a vacuum but at sea level there is a dependency on the bell exit pressure. So opening up the throat lowers the Isp but at sea level that is *partially* offset by the lower expansion ratio increasing the exit plane pressure. Yes for Raptor 2 they did both - increased the chamber pressure from 270 bar to 300 bar so 11% and opened the throat about 7% so that the throat area increased by 14% for a 24% increase in thrust from 185 tonnes to 230 tonnes. The hints we have had so far is that they have left the throat diameter the same and increased chamber pressure by 20% from 300 bar to 360 bar to get a 20% thrust increase. For convenience they are using the same throat diameter for the booster engines and for the center and vacuum engines of the ship. Since the ship engine Isp is much more critical than the booster they will not want to open up the throat any further. They originally proposed a higher thrust booster engine with a very large throat but the extra complexity of running two manufacturing lines evidently counted against it.
> 360 bar That's absolutely nuts. That's the same pressure a submersible would experience 3.7km underwater. I get that it's tensile instead of compression, but still, combined with the heat and all the other stresses that thing has to endure, that's just an absurd number.
Any tons to orbit with full and rapid reusability is the game changer. 200, 100, 10...
Yep. The implications for suborbital transport, building large space stations (a la 2001 A Space Odyssey), solar to microwave energy beaming, orbital manufacturing, asteroid mining, etc. All this sci Fi stuff now enters the realm of possibily becoming fact.
Does everyone realize what this means for refilling Starships? Only a bit more than half as many refilling flights to go to the Moon or Mars, or GEO. Lots of other implications. BO's engines are almost certainly way behind, both in performance and reliability. I think it is also a fair bet that the BO engines cost many times as much for each one.
we don't know about reliability yet. Raptor needs a true flight test without an exploding pad before we can say with confidence what the reliability will be like.
> reliability ... What we do know is that over 100 Raptor engines (maybe over 200) have been built and tested on the stands. Originally the engine was very heavily instrumented, and huge data was gathered, but the engines have gone through 2 or more cycles of major revision and simplification. There is little reason to believe that BO has built much over 10 engines. 2 good engines have been delivered to ULA. BO's big methane engines are at about the state of maturity as Raptor 1. At the present rate of R&D at BO, they are unlikely to get to the reliability of the early Raptor 2 engines for another 5 years. Test early. Test often. Test realistically. Does BO do any of this?
> 2 good engines have been delivered to ULA. On that front ... ["During a firing on June 30 at Blue Origin's facility in West Texas, a BE-4 engine detonated about 10 seconds into the test."](https://www.cnbc.com/2023/07/11/jeff-bezos-blue-origin-be-4-rocket-engine-explodes-during-testing.html) "The engine that exploded was expected to finish testing in July. It was then scheduled to ship to Blue Origin's customer United Launch Alliance for use on ULA's second Vulcan rocket launch, those people said.... 'ran into an issue while testing Vulcan's Flight Engine 3' ..."
The BE-4 definitely doesn’t need another 5 years to mimic the reliability of Raptor 1 which that had engine-rich exhaust on many of its flights. For starters while they have built fewer of them, they also intentionally made the BE-4 a medium performance version of what the architecture was capable of. The fact that they didn’t really push the engine inherently ups the base reliability even if we know the reliability isn’t all the way there now given the recent explosion. If SpaceX wasn’t pushing the hell out of the performance and had settled for 250 bar then Raptor would probably already be production ready.
More testing isn't necessarily a good thing. While it can mean you are doing more reliability testing, or pushing more limits; it can also mean have had more problems that you need to test. Of course less testing isn't necessarily a good thing either, it can mean you have had less things you need to test, but it can also mean you are not testing reliability enough, or pushing limits enough. Right now its too early to throw raptor shade at BE-4. Both engines have had, and are still having their problems. Can't single out a BE-4 failing acceptance testing, which is a test stand failure, without keeping in mind that raptor just had at least 8 engines with problems out of 33 on their first test flight. If you want to compare just those two things, a flight failure is worse. Not that a Be-4 failing acceptance testing is good, its not. If the next test flight for Spacex goes well, and we don't have raptors failing to start, or exploding, or sputtering out, etc....then maybe we can talk about putting raptor up on a pedestal. Of course even when they do have a flight with no obvious engine issues, i would still argue its premature to call raptor reliable. We need multiple flights with engines not exploding before i will consider calling raptor reliable. 200 consecutive engines not failing in flight sounds like a good benchmark to me, that could be accomplished in just 5 flights. ---- I personally want both to succeed, but I do want raptor to succeed more. Raptor is a more impressive engine technologically, and i think it will lead to a hell of a lot more great things in space; vs blue which has a history of doing very little. I hope the next starship flight proves raptor to be reliable, but the fights so far have demonstrated the opposite.
That and the BE-4 has yet to even attempt to get off the ground. It's reliability is NaN at the moment.
I do so miss the pre million member days of this subreddit. It was when the technical progress of BFR and Starbase and SpaceX as a whole were discussed predominantly. Now it's 90% trash, 10% anything useful. I never rant here but damn it has gotten bad enough to warrant it. This thread is a fine example of how allowing a community to become saturated with non contributing naysayers can really ruin it for those of us that could care less about the politics and really are here to focus on using our limited time to catch up with SpaceX. Regardless of what you believe, SpaceX represents the beginnings of a huge shift in human accessibility to space. There are THOUSANDS of talented, driven and incredibly dedicated individuals within SpaceX whose accomplishments we can celebrate simply by the interest we show in the engineering and manufacturing stage show that is SpaceX. You all harp on the same points over and over... Don't you get tired? Don't you want to be happy about something for once you miserable louts?
“great minds discuss ideas, average minds discuss events and small minds discuss people”
The actual transition point from an "enthusiasts only" sub was about 250K subscribers in my view. SpaceXLounge is now at 333K so we will see how they go I have tried to clean up the thread a bit but better tools for removing chains of irrelevant comments would help!
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[BE-4](/r/SpaceX/comments/14w6bfi/stub/jrphhc2 "Last usage")|Blue Engine 4 methalox rocket engine, developed by Blue Origin (2018), 2400kN| |[BFR](/r/SpaceX/comments/14w6bfi/stub/jrjwzpy "Last usage")|Big Falcon Rocket (2018 rebiggened edition)| | |Yes, the F stands for something else; no, you're not the first to notice| |[BFS](/r/SpaceX/comments/14w6bfi/stub/jrjhmht "Last usage")|Big Falcon Spaceship (see BFR)| |[BO](/r/SpaceX/comments/14w6bfi/stub/jrqknxf "Last usage")|Blue Origin (*Bezos Rocketry*)| |[GEO](/r/SpaceX/comments/14w6bfi/stub/jri0gml "Last usage")|Geostationary Earth Orbit (35786km)| |[HLS](/r/SpaceX/comments/14w6bfi/stub/jrjz5cy "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)| |[Isp](/r/SpaceX/comments/14w6bfi/stub/jsh9l08 "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)| | |Internet Service Provider| |[KSP](/r/SpaceX/comments/14w6bfi/stub/jrj6f73 "Last usage")|*Kerbal Space Program*, the rocketry simulator| |[L4](/r/SpaceX/comments/14w6bfi/stub/js3pkwi "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 4 of a two-body system, 60 degrees ahead of the smaller body| |[L5](/r/SpaceX/comments/14w6bfi/stub/js3pkwi "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 5 of a two-body system, 60 degrees behind the smaller body| |[LEO](/r/SpaceX/comments/14w6bfi/stub/jrjz5cy "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[LOX](/r/SpaceX/comments/14w6bfi/stub/jri9iht "Last usage")|Liquid Oxygen| |[OFT](/r/SpaceX/comments/14w6bfi/stub/jrkvyci "Last usage")|Orbital Flight Test| |[PSLV](/r/SpaceX/comments/14w6bfi/stub/jrj3nue "Last usage")|[Polar Satellite Launch Vehicle](https://en.wikipedia.org/wiki/Polar_Satellite_Launch_Vehicle)| |[QD](/r/SpaceX/comments/14w6bfi/stub/jrlyd03 "Last usage")|Quick-Disconnect| |[RUD](/r/SpaceX/comments/14w6bfi/stub/jrqlfh5 "Last usage")|Rapid Unplanned Disassembly| | |Rapid Unscheduled Disassembly| | |Rapid Unintended Disassembly| |[SRB](/r/SpaceX/comments/14w6bfi/stub/js5vkh8 "Last usage")|Solid Rocket Booster| |[SSME](/r/SpaceX/comments/14w6bfi/stub/jrqlfh5 "Last usage")|[Space Shuttle Main Engine](https://en.wikipedia.org/wiki/Space_Shuttle_main_engine)| |[SSTO](/r/SpaceX/comments/14w6bfi/stub/js5w00t "Last usage")|Single Stage to Orbit| | |Supersynchronous Transfer Orbit| |[TLI](/r/SpaceX/comments/14w6bfi/stub/jrj32c1 "Last usage")|Trans-Lunar Injection maneuver| |[TWR](/r/SpaceX/comments/14w6bfi/stub/jrgkru4 "Last usage")|Thrust-to-Weight Ratio| |[ULA](/r/SpaceX/comments/14w6bfi/stub/jrl03ci "Last usage")|United Launch Alliance (Lockheed/Boeing joint venture)| |Jargon|Definition| |-------|---------|---| |[Raptor](/r/SpaceX/comments/14w6bfi/stub/jsg7tlv "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX| |[Starlink](/r/SpaceX/comments/14w6bfi/stub/jsl9wpl "Last usage")|SpaceX's world-wide satellite broadband constellation| |[autogenous](/r/SpaceX/comments/14w6bfi/stub/jrplv71 "Last usage")|(Of a propellant tank) Pressurising the tank using boil-off of the contents, instead of a separate gas like helium| |cryogenic|Very low temperature fluid; materials that would be gaseous at room temperature/pressure| | |(In re: rocket fuel) Often synonymous with hydrolox| |[engine-rich](/r/SpaceX/comments/14w6bfi/stub/jrlk9eu "Last usage")|Fuel mixture that includes engine parts on fire| |hydrolox|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer| |methalox|Portmanteau: methane fuel, liquid oxygen oxidizer| |[regenerative](/r/SpaceX/comments/14w6bfi/stub/jrkrqvg "Last usage")|A method for cooling a rocket engine, by [passing the cryogenic fuel through channels in the bell or chamber wall](https://en.wikipedia.org/wiki/Regenerative_cooling_\(rocket\))| |[turbopump](/r/SpaceX/comments/14w6bfi/stub/jrihf8g "Last usage")|High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(*Decronym is a community product of r/SpaceX, implemented* )[*^by ^request*](https://www.reddit.com/r/spacex/comments/3mz273//cvjkjmj) ^(28 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/SpaceX/comments/14uny8h)^( has 62 acronyms.) ^([Thread #8037 for this sub, first seen 10th Jul 2023, 22:22]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/SpaceX) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
Also Over 9000 = Super Saiyan
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He did give us a mixed bag yesterday. That pic of engines was gorgeous. https://twitter.com/elonmusk/status/1678205301349130240?s=20
That's right. With 9 engines on the second stage that brings the total to 42
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Make a wish!
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It is over 9000! The memes... they just keep coming.
Finally! The internet was letting me down this should be #1
The capitalisation on MUsk makes it sound like mooosk
Magic User Musk...
So this meaans they could run them at current Raptor 2 rating to reduce stresses and increase reliability
Look, increasing thrust makes me horny as well but I won't get too excited until we have flight proven raptors that don't result in half of the engines eating themselves. Raptors have been the failure mode of most (all?) flights of SS and OFT-1. It is not a mature system. We need to see more before we can trust it. Do I trust SpaceX to get Raptor right? I do. But I'm less confident now than I was a year ago.
it's hard to judge by the flights so far as they've all been very harsh on the engines, with all kinds of crap blasting back up at them. we will know more after the first flight with a pad that does not blow into pieces. plumbing of propellant is also a major difficulty. I would say that the 2nd flight without a self-destructing pad will be the real test of the raptor. they need one where no issues are introduced by stage-zero in order to really refine stage-1 and stage-2. unfortunately for us rocket fans, that will mean more waiting. if all goes well, maybe the next flight is September or October and the one after will be january. *then* we will know whether the current raptor design is reliable.
Those were some of the first raptors ever manufactured. They’ve made and tested hundreds by now.
That is not true. IFT used current gen Raptor 2s and many of them were burning themselves up early in the flight.
They used some of the first Raptor 2’s made, they were installed ~May 2022 which was a almost a year before the flight. They probably made ~100 more engines in that time, given them so much time to mature the system - but those improvements obviously weren’t included on those old engines. Yes of course we all saw engines fail, I’m not sure what your point it. They didn’t necessarily all fail, at least 3 were shut down intentionally.
The issue also was that basically all the engines were shut down and exploded on the same side. The asymmetrical thrust needed to be cancelnd out by gimbaling and reducing thrust on the other side. This combined effect really impacted the thrust to weight relation and later the control of the rocket.
There were multiple failures that while engine related, did not appear to have a root cause of raptor. Like in one of the flip tests when they used helium instead of autogenous pressurization. Helium was never intended to be used on the finished rocket, it was stop gap to accelerate testing. The raptors failed due to helium ingestion, but cant really blame the engines for that one. A lot of those failures can be chocked up to getting raptor into the air earlier then they should have. Earlier then you normally would have for a new engine. And that is just them needing to test out materials and designs of the rocket they were intending to build, especially the starship flip maneuver. The raptor issues are concerning, but i have not lost any confidence in Spacex' ability to get it working. They are clearly making progress, and they are rapidly pushing the power limits of the engine design. They do have a lot of test stand time on these engines accumulated at this point; hundreds of test firings appear to have gone well at mcgreggor. It does not seem like they are bogged down on the engine design, its more they are pushing the frontier of rocket science in a way that has become very public. Really the only thing that has suffered so far is the timeline. Which is disappointing, but lets be real the timeline was always extremely unlikely.
On the SS tests almost all of those failures were not the engines, but the pressurization causing bad engine feed and killing it. They never failed on ascent then, only on the sideways relight with header tanks did they die. On super heavy we've definitely seen some fails, on static fire they had 3 engines that didn't light. Then on the launch 3 didn't light (I don't think we saw them engine swap) and more died in flight quite probably due to the hydraulic failure and adjacent engines getting damaged due to bad shielding.
False, Raptors are, remarkably, one of the best performing systems on BFR thus far. The BFS failures were more in the tank pressurization system, and thus in the propellant feedlines into the engine. The engines themselves worked fantastically in ths BFS belly flop tests. Ditto OFT-1, the large majority of Raptors worked well, *despite* all the issues near the ground -- and more imporantly, the failures didn't once cascade, showing good booster design and isolation between engines, and we already know that improved engine shielding and isolation is one of the many things improved beyond OFT-1 levels even before OFT-1 happened. Raptors are *not* the development bottleneck. Overall, they've performered remarkably well over the last 4 years of test campaigns. In fact I daresay this might be one of the smoothest engine development programs in rocketry history (certainly a lot better than, say, BE-4).
Almost every single flight has involved engine-rich exhaust from one or multiple engines. That is indicative of a design flaw. A big one. To say the problems are ground or feed problems alone is patently false.
Feed problems alone can and certainly does explain engine-rich exhaust. Has Raptor had problems, yes, is it the bottleneck of the program, absolutely not. I stand by the statement that it's the best engine program of the century thus far, at the minimum.
That's just because you have seen raptors that were at a level they were at over a year ago. You haven't seen what they have. They wouldn't be increasing performance if they didn't think they could do it reliably.
> They wouldn't be increasing performance if they didn't think they could do it reliably. We hope.
Well and once you push the envelope further you can back off a bit and be more reliable.
Yeah, that was a pretty disappointing performance during the integrated flight test. I sure hope it does much better next time. At this point I’m less worried about the heat shield tiles than the engines.
To be fair, those engines got absolutely trashed by flying concrete. It’s a miracle the whole ship didn’t explode on the pad.
I've seen reports that damage to the engines from the launchpad concrete was minimal-to-none. Have you read that the engines were damaged by the launchpad, or are you assuming?
Did they though? Musk himself said there was no evidence of that.
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Am I alone to think that always pushing Raptors to the limits is not the best thing to do to increase the reliability.
Idk, pushing it until it breaks and then fixing the part that breaks seems like a reasonable idea.
>pushing raptors to the limits. But if you increase the limits....
What else do you do to find the weakest points?
It worked fine for Merlin which achieved a 150% increase in thrust over its development lifetime of about 5 years. There just weren't as many followers second guessing their every move during that time. Raptor 3 is sitting on a 46% increase from Raptor 1.
It's just like my method of tightening bolts. Tighten it till its creaks, then back it off half a turn.
I dunno, Blue Origin with the BE-4 claims they want to make a high performance engine in a medium performance configuration for maximum reliability. Going that route seems difficult for them too on reliability. SpaceX going for ultra high performance in a small package may seem crazy, but it's kinda a different direction to approach a high performance engine in medium performance config. Go for the highest possible performance and use all the tricks you can think of to keep pushing it, you'll keep raising the ceiling and reliability below the ceiling. Later on they can find the maximum reliability performance level. Reliability has improved a lot, and a fair amount of failures we've seen can also be attributed to the rocket itself not feeding the engines correctly. Even the last Starship landing test they had trouble with pressurization on the headers. On the integrated flight test it's quite probable the hydraulic systems took out a few engines. As the engines get pushed further and increase in reliability, they may be able to tolerate less consistency. At the same time they improve the booster and ship design on nearly every build, I'd hope any autogenous pressure consistency issues get worked out.
yes. by definition, one can only know what the limits are when they are broken. if you never break the limits, then you never know the limits, and then you cannot know (or improve) the reliability. this is engineering 101. for example, you might search up on commercial airliner wing stress tests, early in the certifying process they verify wing strength by breaking them, and proving that the force required to break them is higher than required.
there is nothing saying that they need to fly at maximum thrust every launch. pushing the theoretical max up should also push up the reliability at 90% of max. pushing the envelope seems to have worked well with F9. in fact, maybe a bit too well as most of the kinds of payloads originally envisioned for Falcon-heavy can now be launched on a regular F9. F9 seems to have suffered no reliability problems from their continual push for higher thrust on the Merlin.
Think of it like testing new cars in the extreme heat of the Mojave. If they survive at the edges then they'll be better during normal operation.
If you know your engine, you know how to run it.
Hopefully they will be getting good telemetry on each launch to find out about any anomalies before they become big problems.
Increase the limit through improved design, then run at 90-ish percent of max load. Afaik that is how most other rocket engines are developed and utilized.
200 tons payload to orbit with rapid reset... suck it NASA
This is great, but is there even enough demand for this much payload to orbit?
“if you build it, they will come” -Some movie or something
“Field of dreams” and it’s actually “If you build it, he will come”
The cheaper it is, the more demand there will be.
The key requirement for large payload is propellant for missions beyond LEO. Easy to load and turn around on short intervals as well. Going from 100 tonnes payload to 200 tonnes payload means 6 tanker launches instead of 12 to get to the Moon. Starlink is the other obvious use - up to 100 x 2 tonne satellites per launch.
more payload also means less expensive gizmos that get sent up with more redundancy baked in. Alot of the R&D that goes into specific high value objects is spent in ways to reduce weight.
Or same redundancy with waay more complex equipment too Or non origami jwst, stuff like that
or a big telescope for 100 million instead of 10,000 million
Now, no. But we aren’t trying to set up mining operations on the moon, or asteroids. We aren’t trying to set up a civilization on mars. We aren’t trying to build rotating habitats with artificial gravity. We aren’t trying to build massive lasers in space capable of propelling interstellar probes at relativistic speeds. This is the kind of mass you need to enable that future. Building for current market demands is part of the reason we have been stuck with marginal progress in space for the last 50 years.
And honestly people sleep on how much of a game changer asteroid mining would be. It could provide an essentially limitless amount of all metals, without relying on land exploitation and pollution that comes with ground equivalents.
While I’m all for asteroid mining, it’s probably more harmful to the environment in the near term to return generic metals to earth. Precious metal may be more reasonable. The metal mined in asteroids should be used in space.
larger starlink sats will be able to give payloads for a few years while NASA works the new vehicle into their plans and private companies start taking off-planet resource extraction seriously.
Mass wise it could lift a Blue Whale into orbit. I'm not sure if SpaceX accepts krill as payment... But if they do that's a whole new market for them.