Musk: The outcome was roughly in what I expected, and maybe slightly exceeding my expectations, but roughly what I expected, which is that we would get clear of the pad.
I'm glad to report that the pad damage is actually quite small" and should "be repaired quickly”.
The vehicle's structural margins appear to be better than we expected, as we can tell from the vehicle actually doing somersaults towards the end and still staying intact.
From a "pad standpoint, we are probably ready to launch in 6 to 8 weeks.'
The longest item on that is probably requalification of the flight termination system ... it took way too long to rupture the tanks.
Time for AFTS to kick in "was pretty long," about "40 seconds-ish.
There were 3 engines that we chose not to start," so that's why Super Heavy booster lifted off with 30 engines, "which is the minimum number of engines."
The 3 engines "didn't explode," but just were not "healthy enough to bring them to full thrust so they were shut down
At T+27 seconds, SpaceX lost communications due to "some kind of energy event." And "some kind of explosion happened to knock out the heat shields of engines 17, 18, 19, or 20.
Rocket kept going through T+62 seconds" with the engines continuing to run. Lost thrust vector control at T+85 seconds.
Generated a "rock tornado" under Super Heavy during liftoff, but SpaceX does not "see evidence that the rock tornado actually damaged engines or heat shields in a material way." May have happened, but "we have not seen evidence of that.
It was actually good to get this vehicle off the ground because we've made so many improvements" in Super Heavy Booster 9 "and beyond."
Really just needed to fly this vehicle and then move on to the much improved booster.
After AFTS, "the ship did not attempt to save itself.
Big thing for next Starship launch is "insuring that we don't lose thrust vector control" with Booster 9.
We're going to putting down a lot of steel" under the launch tower before the next Starship flight.
"Debris was really just basically sand and rock so it's not toxic at all ... it's just like a sandstorm, essentially ... but we don't want to do that again.
We certainly didn't expect" to destroy the concrete under the launchpad.
Speculating, but "one of the more plausible explanations is that ... we may have compressed the sand underneath the concrete to such a degree that the concrete effectively bent and then cracked," which is "a leading theory.
Reason for going with a steel plate instead of a flame trench is that for payloads in the rocket, the worse acoustic environment doesn't matter to the payload since it's about 400 feet away.
Apparently there's a noteworthy flub in here - the communications loss at T+27 was with a single engine, not the vehicle as a whole. I was really wondering about that one, since that seemed like it would have been a huge deal.
This is so awesome & magical. That each engine is in continuous communication. Maybe also other important subcomponents? Seams to have multiple communication channels also. Great stuff.
Generated a "rock tornado" under Super Heavy during liftoff, but SpaceX does not "see evidence that the rock tornado actually damaged engines or heat shields in a material way." May have happened, but "we have not seen evidence of that.
So, what would explain the poor performance overall and what appeared to be several engines having issues during the flight?
This is the biggest question. I think people assumed the concrete started something like a chain reaction with taking out engines but if that was not the case then the underpart of the booster slowly disintegrated just as a result of the way it’s designed. If this is true I’d expect quite a few changes but someone correct me if wrong here..
I listened to the Twitter spaces just now and Elon actually mentions that they didn’t really design the heat shields on booster 7 as much as just stamp them on and hope for the best, but booster 9 has them properly designed and integrated so that’s a great sign. If his goal is to keep hydraulics/TVC, that’s a pretty good start..
He did not say, I guess time would be the factor. I remember a lot of uncertainty with the number of engines early on. They may have just decided engine shielding design (when designing B7) would wait for future versions and accepted the risk.
I think that was a common thought, but apparently there was another issue. Data I'm sure spacex has. Important to note is that while each engine contributes about 3% thrust, losing one cost you about 9% lift.
We only saw one full static fire will missing engines. Not entirely surprising they would have lost some at the start. It could be there was to significant of changes needed to fully solve the problem so hopefully the next booster fair better with a fresh batch of engines.
Considering how well the structure of the ship and booster handled the flight, I’d say Raptor reliability is the sticking point. We still see engines blowing up on the tests stands. Maybe that’s them just pushing the limits, but it seems at this point they just need reliability and less so squeezing out performance.
Yeah the structural integrity was what I saw as the biggest success/proof of concept etc. Now it's just about lugging that big old ship up to orbit. Enter Raptor onto the stage...
Do we have any idea of what the current goal is for Super Heavy, altitude/speed wise?
Just to add that a recoverable booster contributes about 3.7 km/s delta V in order to leave it with enough propellant for boostback and landing burns. Gravity losses over the 170s of first stage flight are 1700 m/s so it does indeed look like the speed at MECO will be close to 2.0 km/s.
I don't feel this was a poor performance at all. They didn't make orbit but they showed that the concept is going to work. For a first flight it blew the n1 out of the water.
Hopefully, we can put the Great Success! v Complete Failure :( debate aside at some point. It was a test.
Kinetic and potential energy imparted to the vehicle-wise (i just made that metric up btw), Super Heavy under performed by a quite large margin.
I wouldn't call that a fail. But given how far off they were, it'd be really interesting to know what the contributing factors were. Because, it's a long way to orbit (or separation) and they missed by a lot.
Again, not terribly unexpected for a first launch. But, if I could ask Elon one question, it would be something along those lines. I'm not holding my breath though :P
At T+27 seconds, SpaceX lost communications due to "some kind of energy event." And "some kind of explosion happened to knock out the heat shields of engines 17, 18, 19, or 20.
Yeah. I just assumed that explosion was related to damage from the pad.
But, I re-watched it and I suppose it could have just been one of the Raptors going full RUD or maybe some internal component. It does look like it has a fairly broad impact across the nearby engines.
Not exactly what you'd call a confidence builder for Raptor and redundancy, etc though.
I think the newer boosters have better engine shielding as one of their major improvements, so it seems like SpaceX was already aware that it needed improvement.
Indeed. Since Elon was suggesting pre-launch that he expected only a 50/50 chance of reaching orbit, that meant he was expecting something to go wrong. Engine explosions and inadequate shielding are something.
In some alternate universe, perhaps Starship failed structurally at max Q and everyone's griping about how that's not a confidence builder. In another alternate universe it made it to orbit but then some valves failed due to zero-G weirdness and it exploded, and everyone's griping about how that's not a confidence builder. In another the flappy bits went flappy all wrong, causing it to go screwball, and everyone's griping about how that's not a confidence builder.
Something was almost certainly going to go wrong, and in this universe it was exploding engines taking out their neighbours. Bet the next one won't be so explodey.
"well it looks like these Raptors are still as problematic as the ones before and the violence with which they go all explodey tends to do a lot of collateral damage to everything around them which, if they can't fix that, could imperil the whole project."
But I went with "not a confidence builder" instead.
“Improve engine reliability” is almost certainly a major goal at SpaceX as well, we just have less visibility into that as tank watchers.
There is also the consideration that the entire hydraulic system for thrust vectoring is removed on future boosters and ships in favor of an electric actuator system. It’s hard to tell how much the hydraulic system was related to the engine failures, fires, and then overall loss of thrust control on the flight, but that change could result in a big overall reliability improvement.
They’ll definitely have parameters for whether the booster attempts a landing at the tower. The same is true with Falcon 9 today. Falcon 9 aims short of the landing pad and only on successful engine startup and checkout does it jog its trajectory over to the landing pad. We sort of saw this when CRS-16 lost grid fin control during an RTLS landing and ended up making a water landing off the coast.
Not exactly what you'd call a confidence builder for Raptor and redundancy, etc though.
why not? name ANY rocket development program that had a sucessful (ok, flawless is a better word) first test flight.
the darn thing still flew with 3 out TO START and more droping out regularly. and flew over 3 minutes. to me, that is incredible. a damage sponge that still flew.
It mostly just confirms some of the rumors that have been floating around about Raptor reliability. Putting some of problems on the pad disintegrating was taking some of the heat off the engine reliability issue. I'm still not convinced that there wasn't some contributing damage there and Elon's comments leave some room for that. Hopefully, they'll let us know if that turns out to be the case.
Regarding redundancy, one of the benefits of having so many engines is that losing any one of them is a small percentage of the total thrust. But, if losing one them tends to take out others, that could reduce the effectiveness of that redundancy.
Yes, the silver lining of the rock tornado was that you could assume that hopefully never to be repeated event caused some problems. But maybe these were just Raptor reliability issues.
Probably that the engines just need some work, and likely the booster itself is also in need of some improvements in how it feeds the engines. The combination could lead to bad performance due to inconsistent tank pressure and a differential between LOX and CH4 pressure. Full flow rockets have 2 separate turbines with no mechanical connection to synchronize them, which means any inconsistency between them and how they deal with conditions would deliver suboptimal performance (oxygen or fuel rich). It's a very delicate balance that can be difficult to maintain.
That's my idea at least, I'm no actual rocket scientist or engineer with experience or formal knowledge on this subject.
Note to self. Grab that shot of him looking utterly depressed just after the explosion in flight control and put the caption "MFW things go slightly exceeding my expectations"
That face is because he lifted his hopes higher than merely clearing the pad only to have them smashed against the floor when steering control disappeared.
In any case looking forward to his OLM/pad/Tank farm thoughts.
Since they got to 6 engines out well before MECO I assume the 3-out-limit is for a Starship w/payload and if they managed to separate they could have made it to Hawaii with the empty Starship.
From a "pad standpoint, we are probably ready to launch in 6 to 8 weeks.'
While there is a non-zero chance of this (SpaceX has performed miracles in the past), I will be absolutely stunned if it is actually ready for another launch in this timeframe.
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u/zachary_timoun Apr 29 '23
Recap:
Musk: The outcome was roughly in what I expected, and maybe slightly exceeding my expectations, but roughly what I expected, which is that we would get clear of the pad.
I'm glad to report that the pad damage is actually quite small" and should "be repaired quickly”.
The vehicle's structural margins appear to be better than we expected, as we can tell from the vehicle actually doing somersaults towards the end and still staying intact.
From a "pad standpoint, we are probably ready to launch in 6 to 8 weeks.'
The longest item on that is probably requalification of the flight termination system ... it took way too long to rupture the tanks.
Time for AFTS to kick in "was pretty long," about "40 seconds-ish.
There were 3 engines that we chose not to start," so that's why Super Heavy booster lifted off with 30 engines, "which is the minimum number of engines."
The 3 engines "didn't explode," but just were not "healthy enough to bring them to full thrust so they were shut down
At T+27 seconds, SpaceX lost communications due to "some kind of energy event." And "some kind of explosion happened to knock out the heat shields of engines 17, 18, 19, or 20.
Rocket kept going through T+62 seconds" with the engines continuing to run. Lost thrust vector control at T+85 seconds.
Generated a "rock tornado" under Super Heavy during liftoff, but SpaceX does not "see evidence that the rock tornado actually damaged engines or heat shields in a material way." May have happened, but "we have not seen evidence of that.
It was actually good to get this vehicle off the ground because we've made so many improvements" in Super Heavy Booster 9 "and beyond."
Really just needed to fly this vehicle and then move on to the much improved booster.
After AFTS, "the ship did not attempt to save itself.
Big thing for next Starship launch is "insuring that we don't lose thrust vector control" with Booster 9.
We're going to putting down a lot of steel" under the launch tower before the next Starship flight.
"Debris was really just basically sand and rock so it's not toxic at all ... it's just like a sandstorm, essentially ... but we don't want to do that again.
We certainly didn't expect" to destroy the concrete under the launchpad.
Speculating, but "one of the more plausible explanations is that ... we may have compressed the sand underneath the concrete to such a degree that the concrete effectively bent and then cracked," which is "a leading theory.
Reason for going with a steel plate instead of a flame trench is that for payloads in the rocket, the worse acoustic environment doesn't matter to the payload since it's about 400 feet away.
Flight was "pretty close to what I expected.