Starship – SN8 – High-Altitude Flight Test
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Successful ascent, switchover to header tanks & precise flap control to landing point!
Fuel header tank pressure was low during landing burn, causing touchdown velocity to be high & RUD, but we got all the data we needed! Congrats SpaceX team hell yeah!!
It seems that the Raptor engines didn't failed due to defects at the end of the landing. The fuel pressure from the header tank wasn't high enough and the engines became fuel starved. It is obvious in the video as the engine exhaust became bright green at the end, a sign that the engine was restarting by TEB.
Edit:
https://twitter.com/elonmusk/status/1336810077555019779
Mars, here we come!!
Indeed
https://en.wikipedia.org/wiki/Mercury-Redstone_1
Technically the Shuttle go or blow moment is when the SRBs are turned on.
But yes, otherwise in the spirit, it will either blow up or be generally sucessful.
And as others have said, it's either complete success-or-explosion that's expected in this area.
They didn't stick the landing, but it looks like they got test data from all the planned test activities. The explosion will prevent gathering some data from post-flight inspection, but other than that I doubt it has much affect on future development.
To look back on SN5/SN6 testing, they stuck the landings with those prototypes, but the prototypes themselves are now obsoleted by the new prototypes in production (up to SN16?!)
Seems to be a great benefit of this method that SpaceX is following with Starship: if you build hardware fast and cheap enough, you can afford some partial failures since you just put the lessons learned into the next flight in a few weeks.
As problems go, that's a relatively simple one that they ought to be able to address. The ascent appears to have been successful (though for a few moments it looked like something caught on fire and I'm not sure if that was planned or expected). The glide worked. The rocket was able to navigate to the landing pad.
Next time they'll be working with a lot more information. This seems like overall it was a success, even though they're down one rocket and three engines. A failure would have been the rocket blowing up on the pad during launch or other similar mishap from which they wouldn't have learned much aside from "make sure that doesn't happen again".
Good thing you aren't the one designing these things.
Even if this model had worked perfectly, it's unlikely they ever would've flown it again. Remember, SpaceX's goal is to mass produce these.
Much better to fail hard now and in many different ways, as the more problems you can find with your expendable prototypes the better (before your manufacturing process starts to ossify).
News anchors? They're often pretty clueless about technical things, so their mistakes don't mean much.
The primary objectives of the test were completed without any issues. If that doesn't meet your definition of success, I don't know what to tell you...
The flip down to gliding just looked so bizarre and futuristic.
It's the big WTF I got from first seeing Grasshopper stop and hover in mid air and land again. That's not what rockets are meant to do!
Except of course they are meant to do it!
The Lunar Lander was piloted since the computers couldn't do everything, but at the same time a human was good enough at piloting to be able to take over for what the computer couldn't do.
This is the result of modern day CFD that that would take humans millions of years to do by hand
the package as a whole, yes.
belly reorientation for flight has been a thing since the early American arms' race. It's a useful missile trait.
Gimbaled vector rockets have existed since the 1940s.[0]
Yes, restart is very important -- it's not a requirement for atmospheric belly flight, though.
Robert Brulle has a fascinating memoir https://www.airuniversity.af.edu/Portals/10/AUPress/Books/B_...
Maybe because they want to be able to keep it for posterity if it makes it - or launch it again!
From memory I think it blew itself up in the air when something went wrong, rather than crashing.
• 45,000 feet is a lot farther that 450 feet. • Falling and using movable aerodynamic surfaces to descend in reentry position, then rotating into landing position is kind of hard.
• Running rocket engines for over four minutes straight is hard, BO has barely run their engines more than 4 minutes total in years of ground tests, without the realism of actual flight and its associated vibrations and accelerations.
• Restarting rocket engines is hard.
Lastly DC-X cracked up its last landing too.
The real issue is why did it have retractable legs in the first place, esp on a test vehicle. Sounds like a great to start writing a post mortem is in the design phase.
For the people not familiarized
I’m not 100% on this, but I think the raptor actually runs really oxygen rich. According to Elon’s tweet and Wikipedia, it runs 3.5-1 O2-CH4. It runs so lean that the unburnt o2 cools things.
If it were running closer to 1-1 (low ch4) then it would run much hotter and burn things like we saw.
Edit: reading more I’m not positive they run O2 rich anymore
The second turbopump, to which tdy721 is referring, sits right above the injectors and runs oxygen rich. This oxygen rich exhaust is the oxidizer input for the combustion chamber.
I know very little about rocket engines, but I would imagine that the fuel pre-burner, which appears to be intended to run extremely fuel rich, might have some serious problems if it didn’t have enough fuel coming in. Aside from just generally not working, it could internally burn much less fuel rich and therefore much hotter than intended, resulting in any number of failure modes.
However, SpaceX is also tuning for engine temperature control and specific impulse. Raptor runs ~3.55 lox/methane (very rich), 4.0 is stoich.
https://www.researchgate.net/publication/255632584_On_the_Of...
Excess hot oxidiser on the other hand can often fuel. Like the combustion chamber wall.
sitharus means that the excess oxygen will oxidize (burn) things other than methane if there is enough oxygen present at the temperatures and pressures found in a rocket engine combustion chamber. It will oxidize (burn) things that you wouldn't normally think of as "fuel", such as the copper in the metal alloys.
Your engine is now full of solid projectiles that take out other parts, fuel lines and injectors, damage film cooling nozzles and coolant canals, and in general transform your precision machine into a smoldering pile of gunk.
also, from the pictures I've seen, the turbopumps are about the size of a propane tank, even smaller than a truck engine.
Source: https://mobile.twitter.com/elonmusk/status/11773871411160023...
They wouldn't carry enough TEA/TEB to make that much flame - it's likely the engine itself burning. Also I don't think Raptor uses TEA/TEB as that would put a cap on the number of restarts - not something you want for an interplanetary mission!
> Mars, here we come!!
None of that information was official though so take it with a grain of salt, it's all come from personal knowledge and analysis by some people watching.
The orientation change just prior to shutoff is also a clue: https://twitter.com/joebarnard/status/1336820348071849986
The same may have happened for the fuel, I guess lowering the pressure? I know nothing about rockets.
The Raptor doesn't use TEB. It uses spark ignition.
The green is most likely 'engine rich' exhaust. Meaning the cooper cladding of the engine bell started to burn away.
Having completely cylindrical body and two sets wings now for the prototype phase makes control authority good and iterating changes very easy (you can change either wing shape easily), even if it's not optimal mass wise.
Seems to be working for SpaceX. Makes for impressive videos too.
Congratulations to all involved.
Even if another company decides to try to replicate what SpaceX is doing, they're now at least a decade behind.
Nobody has the present institutional knowledge that they have.
My gut says that if they don't test they can't deliver, and that Elon's rapid prototyping will keep SpaceX far in the lead for the foreseeable future. But only time will tell.
It has plans to someday build a competitor to the 13 year old Falcon 9.
Oh and Bezos started BO before SpaceX, and has given it substantially more funding.
Seems to me that they may be trying to pivot away from having orbital rockets being their main product with the sale of BE-4 engines to ULA for Vulcan and all of their work on lunar projects. But that could also be them trying to get more friendly with NASA or get development of the BE-4 paid for or any number of other things. They certainly are lacking in terms of actual hardware being seen.
There is one entity that can and will rapidly close that gap. In fact, they're the only one that can: China. Everyone else will continue on their slow path, more or less adopting everything SpaceX figures out a decade after the fact. The other competition operates permanently by hand-me-downs. China will invest huge sums of money and labor into doing the same thing and the difference between them and eg the Europeans, is the Chinese will and can move with ridiculous speed by comparison. The other competition won't adjust their speed, so they'll generally continue to lag SpaceX perpetually, whereas China can move at a far greater pace (aerospace, as with a few other big segments like semiconductors, is of course a core logical focus point for China, which means they will catch up no matter the cost; they'll borrow from SpaceX better than anyone else and faster than anyone else, right up to the point of copying everything). And to be clear, I don't fault China at all for that approach, it will work very well; they can leapfrog everyone not named SpaceX that way.
China has not yet itself produced an engine anywhere close to a Raptor and they have been trying for quite a while.
China can not spend gigantic amounts of money on everything at once, and even if they do, it by far doesn't work all of the time.
When you are copying SpaceX you are always cooping something that is already outdated and SpaceX will not stop innovating.
In 2020, China has launched more rockets to space than any other nation.
https://en.wikipedia.org/wiki/Chang%27e_5
It has a mission to bring lunar rock back to earth for the first time since the 70s.
So I would say that China has put quite a bit of energy in this area and is moving faster than other nations but not as fast as SpaceX.
They should be justly proud of their robotic lunar missions though.
> It has a mission to bring lunar rock back to earth for the first time since the 70s.
Yes its a fine mission, but its a mission that is not outside of the capability of others. There are simply many space missions that could be done.
Yes, China is doing things and the are moving fast, but your prediction and text were still over the top.
http://www.hayabusa2.jaxa.jp/en/enjoy/material/factsheet/Fac...
The Chinese literally haven’t done anything novel in their space program. Even the words they said upon landing on that mission were a copy of the Americans. ‘"It's a small step for the rover, but one giant leap for the Chinese nation," Wu Weiren, the chief designer of the Lunar Exploration Project, told state broadcaster CCTV.’ The Chinese literally can’t do anything but copy and it’s embarrassing.
https://phys.org/news/2019-01-chinese-rover-exploring-dark-s...
No, I'm not kidding.
https://arstechnica.com/science/2019/11/china-keeps-dropping...
The Electron can put 600kg into low Earth orbit.
Falcon 9 can handle 15,000 kg. Starship is expected to handle 100,000 kg.
The Falcon 1 is a good comparison to the Electron. If it had been fully developed it was expected to lift 600kg to leo by 2010 or 2011. 10 years ago, basically.
> they're now at least a decade behind.
The original claim was that competitors are a decade behind spaceX and Electron's capabilities are comparable to the technology spaceX had a decade ago. The Falcon 9 comparisons are to highlight the decade delta.
edit: grammar
I'm sure they'll learn an immense amount from it, and it was amazing to see it nearly pull off the landing. Given the way that Falcon 9 early landing attempts went, it'll go the same way with Starship, and it'll be landing soon.
I realized that this may have been done to slow down the acceleration to make sure it doesn't go past the 12 km limit. I may be wrong though.
Yeah and then something caught fire near the engines. I expected it to explode that very moment.
Edit: ah, it's answered here https://news.ycombinator.com/item?id=25366736
The green flame here is unintended engine ablation :) The chamber was melting.
This is an artifact of air flow vortices around the base of the rocket and its skirt and is completely normal. This video [1] explains it well.
I assume SpaceX has the same video feed with superimposed telemetry. I'd love to know turbo pump pressure and rpm during landing.
Engine 1 cuts off 1m45s after launch
Engine 2 cuts off 1m28s after engine 1
Engine 3 cuts off 1m28s after engine 2 and then SN8 goes into glide testing.
The extra time on all 3 engines is probably to gain sufficient height?
The test was great, it proved the concepts in principle do work in practice, and proved that the design fundamentally works. Launch, high altitude, belly flop and flip and burn landing. I'm excited to see the coming tests, design improvements, and to watch the thing land without blowing up.
Well...that thing looks exactly the same. Shows what I know.
Their welding technique has come a long way since then!
Here is a comparison shot: https://www.reddit.com/r/SpaceXLounge/comments/j7g07d/compar...
Video of the failure: https://youtu.be/3nTSubYzQOM?t=14
Here is Mark 1:
https://www.spacex.com/static/images/starship/STR_9.webp
Here is Serial Number 8:
Russian Space agency "Roskosmos" strikes back - it plans to produce alcohol, perfume, clothes, etc. under the trade mark "Poehali" ("let's go") - the word famously uttered by Gagarin when the rocket started to ascent.
(in Russian) https://lenta.ru/news/2020/11/13/poehali/
Also comes to mind the "Souz vs. Crew Dragon" tweet couple months back by a Russian cosmonaut which brought the Roskosmos CEO and the other top bureaucrats there into boiling publicly with rage https://twitter.com/Msuraev/status/1313945340039528448/photo...
As Russian joke about road building and everything else that requires any concerted effort goes - "There are 2 possible alternatives, a realistic one and a fantasy one. The realistic one is when aliens come to Earth and accomplish it for us. The fantasy one is when we accomplish it ourselves."
For example Russia has been for several years trying to build a new spaceport in the Far East. After the first years of tremendous corruption discovered and prosecuted, the total control, audit and surveillance there have been unparalleled, yet despite it there have already changed several waves of the top/mid management - they get assigned there, steal a lot, get arrested, and new people get assigned, ...
This is just an illustration of what the state of things currently is around Russian space efforts. To change that requires changes above that in government operations.
There are still a lot of capable engineers and even managers in space industry. But being capital and material heavy, space industry can't hide from corruption, which isn't going anywhere while Kremlin is as it is today.
Soyuz spacecraft is a wonderful machine, but lately it more and more served as largely a cash cow and political facade. With Crew Dragon flying, that role diminishes. Given that Proton doesn't provide either, Russian space is left with just a few venues for development. It's hard to see bright sides there until incentives would change.
Examining the wreckage will tell SpaceX lots about structural defects/overbuilt areas.
Edit: SpaceX has invented a vastly better process for innovation. That's what should be scaring the others.
Where a more traditional aerospace company would go out of their way to avoid failures at any step, SpaceX embraces them so long as nobody is endangered in the process.
Incredible test! The "bellyflop" maneuver was the main test objective I think, and it appeared to work. They need to figure out the causes of the engine failures now.
https://www.spacex.com/vehicles/starship/
> As early as Wednesday, December 9, the SpaceX team will attempt a high-altitude suborbital flight test of Starship serial number 8 (SN8) from our site in Cameron County, Texas. The schedule is dynamic and likely to change, as is the case with all development testing.
> This suborbital flight is designed to test a number of objectives, from how the vehicle’s three Raptor engines perform to the overall aerodynamic entry capabilities of the vehicle (including its body flaps) to how the vehicle manages propellant transition. SN8 will also attempt to perform a landing flip maneuver, which would be a first for a vehicle of this size.
> With a test such as this, success is not measured by completion of specific objectives but rather how much we can learn, which will inform and improve the probability of success in the future as SpaceX rapidly advances development of Starship.
> This past year alone, SpaceX has completed two low-altitude flight tests with Starship SN5 and SN6 and accumulated over 16,000 seconds of run time during 330 ground engine starts, including multiple Starship static fires and four flight tests of the reusable methalox full-flow staged combustion Raptor engine. Additionally, with production accelerating and fidelity increasing, SpaceX has built 10 Starship prototypes. SN9 is almost ready to move to the pad, which now has two active stands for rapid development testing.
> SN8’s flight test is an exciting next step in the development of a fully reusable transportation system capable of carrying both crew and cargo to Earth orbit, the Moon, Mars, and beyond. As we venture into new territory, we continue to appreciate all of the support and encouragement we have received.
> There will be a live feed of the flight test available here that will start a few minutes prior to liftoff. Given the uncertainty of the schedule, stay tuned to our social media channels for updates as we move toward our first high-altitude flight test of Starship!
1: Successful ascent, switchover to header tanks & precise flap control to landing point!
2: Fuel header tank pressure was low during landing burn, causing touchdown velocity to be high & RUD, but we got all the data we needed! Congrats SpaceX team hell yeah!!
3: Mars, here we come!!
1 - https://twitter.com/elonmusk/status/1336808486022258688
https://www.reddit.com/r/spacex/comments/ka34n6/elon_musk_fu...
And an analysis video from Scott Manley:
The footage SpaceX got with this launch, particularly that pad view Manley had of it falling directly towards the camera and then flipping was insane.
Rocket fuel, to my knowledge, does not contain any of those ingredients. Can someone explain what happened there? Was this planned?
EDIT: Correction: Raptor doesn't use TEA-TEB.
https://en.wikipedia.org/wiki/Colored_fire
But given the extreme conditions, a number of other factors could be at work.
http://photos1.blogger.com/blogger/1613/496/1600/Merlin1C_Ch...
Seriously getting downvoted? That's what caused the issue.... Elon already tweeted they had low fuel pressure...
Other answers mention TEB starter fluid but I don't think that's right, because as far as I know Raptor has spark ignition only.
edit: Elon Musk just tweeted that the immediate cause of the crash was low pressure in the fuel tank, so that would make sense, as running oxygen-rich would overheat and melt the engines.
I will remember this as long as I live.
EDIT: ... and they just posted a new road closure. How many days before SN9 flies?
If that was your (or anyone else's) reaction and you'd be interested in learning more about what we're doing and how you might fit it, I'd be happy to chat! I'm a manager for one of the software teams here - we're always looking for great engineers who care about the mission!
I'm not American.
Edit: and there are other locations too, including Redmond, WA.
Regardless, as I type this, there are no contact details in your profile.
...provided they are US citizens.
Being born on the 4th July 1969, I always had a fondness for Apollo and rocketry in general. Always wanted to move to the USA as well, but my life's route took me elsewhere :) (although I /did/ once launch a rocket with the MARS team in Black Rock desert in 2001 in an attempt to break the UK amateur rocketry record! [http://www.mars.org.uk/phoboseav.html])
That SN8 flight was beautiful. The Belly Flop manoeuvre... wowsers!
I'm content now at 51 to watch you and the rest of the SpaceX team make history.
Do awesome stuff!
(To be explicit; I don't believe it was faked. There was far too many people watching. But I can understand why the gut reaction may not agree.)
But in all seriousness, I suspect they were prepared for it to hit the ground. Once it left the ground, that part was guaranteed.
The fuel here is methane and oxygen, nothing problematic. I know the shell is very thin and only maintains integrity due to pressure but it would still have to be pressurized to 1 atm for the trip and wouldn't be subjected to forces once in space..
Is that what happened, or was it perfectly normal?
It looked like most of the flight went just as planned except for the engine relight at the end.
https://twitter.com/elonmusk/status/1336809767574982658
The fuel flow must have dropped, leading to oxygen-rich, and then engine-rich combustion.
<giant fireball, smoke, bits of rocket>
"Incredible work team, nice work!"
That cracked me up.
Landing was a secondary objective, and even there they seem to know exactly what went wrong (which means it was a very good test).
Amazing, flying wheat silo!
How many G’s is it pulling?
Those crevices between the flaps, seems like great places for the atmospheric re-entry heat to punch through and destroy the Starship.
I would assume that during the initial re-entrant speed, the flaps would be locked, to minimize errant heat from entering the inner mechanisms. Then after it’s bled off most of its speed, at the last few kilometers off the ground, would the flaps begin to actuate and adjust to the air speed of terminal velocity.
I wonder if atmospheric re-entry is the bigger test, should they succeed with SN9.
Some of this stuff is hard,and you're not expected to understand it without work. So don't just flip it off and say "I'm not smart enough" ... recognise that with work you can understand it, and if you choose not to put in the effort, that's your choice.
There's a lot in this world that takes time to work on, and time to come up to speed with. If you have seventeen lifetimes then you can do a lot, but otherwise you need to make choices. There's a lot you can appreciate from the sidelines, and agree is amazing, without necessarily understanding it all.
But other things you will want to get stuck into and get your hands dirty with, and it takes time and effort.
Smart isn't where it's at ... persistence and resilience are the critical components, combined with a desire to make progress. Absolutely you can look at something and choose not to engage with it, but if you're interested,have a go! Be methodical, be persistent, read around, ask questions, and go for it.
By the way ... I certainly don't know everything ... far from it ... very, very far from it, but if ever there's something you think I might be able to help with, just let me know. If I can't help, I'll say so. If I can, I'd be happy to do so.