SpaceX Launch Not So Perfect After All
First time accepted submitter drichan writes "Those of us who watched the live feed of last night's Falcon 9 launch could be forgiven for assuming that everything went according to plan. All the reports that came through over the audio were heavy on the word "nominal," and the craft successfully entered an orbit that has it on schedule to dock with the International Space Station on Wednesday. But over night, SpaceX released a slow-motion video of what they're calling an 'anomaly.'"
An anomaly? That's strange.
rewriting history since 2109
The Falcon 9, as its name implies, has nine engines, and is designed to go to orbit if one of them fails. On-board computers will detect engine failure, cut the fuel supply, and then distribute the unused propellant to the remaining engines, allowing them to burn longer. This seems to be the case where that was required, and the computers came through. The engines are also built with protection to limit the damage in cases where a neighboring engine explodes, which appears to be the case here.
Sounds like it did exactly what it was supposed to do.
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The engine failure of the falcon 9 engine #1 is not really a bad thing. It served to prove the reliability of the shutoff system, and flight control hardware.
Considering the horrendous failure rate of NASA's early engines, (the kind that explode spectacularly), this managed failure situation is very promising.
Rest assured, there will likely be a strong inquiry concerning the manufacture and design of the engine fairing that failed, causing the pressure drop, and engine shutdown.
Managed failures like this one don't speak poorly of spacex. On the contrary. They show spacex planned ahead, and the failsafes they built actually work.
If you sell your system as being fail safe you can market it two ways.
1. Trust us it's fail safe.
2. Told you so.
Yeah, they had a engine fail, but the system shut it down and the other engines compensated. You've got data from the failed engine and you've got the assurance that your system works sans 1 engine. This outcome only makes SpaceX better.
TFA only tells half the story. MSNBC has more. Dragon is fine, but it's possible that the launch's secondary objective, which was to put the first of an 18-satellite telecom array into a tricky high-inclination orbit, went a little screwy as well, and the sat isn't in the proper orbit at the moment. Details are still being dug out.
Everything is better with chainsaws.
– Both Saturn V and the shuttle launch system were designed to handle failure of at least one engine
– The entire engine didn't actually explode, as some sources have reported; the onboard computers were still sending data from it (SpaceX believes it was just the aerodynamic casing (fairing) that exploded, due to the pressure release of the engine)
– This doesn't mean the Falcon 9 system is necessarily less safe than NASA systems; on two occasions, Saturn V rockets experienced a similar loss, with similar (i.e., nil) impact to the mission's success
So, y'know. Rejoice nerdily about the fact that the failsafes worked, rather than worrying about commercial technology being inferior.
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Pilots say any landing you can walk away from is a good landing.
In space, any launch that accomplishes its goals is a good launch. If good costs 10% of perfect, go for good.
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Looks like we've had our glitch for this mission
We've been "pre-disastered". http://www.imdb.com/title/tt0084917/
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How many of those nine engines can fail before the system cannot compensate?
Shut up, Fruitloops...
Do not look into laser with remaining eye.
9 engines of LOX on the rocket, 9 engines of LOX
drop one down, blow it around
8 engines of LOX on the rocket....
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I've been playing too much SpaceChem...
xkcd is not in the sudoers file. This incident will be reported.
There was a big bang, in theory.
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none of Falcon 9â(TM)s other eight engines were impacted by this event.
God I hate this wording.
Don't use "impact" when you mean to say "affected", as I suspect they mean here, especially when the sentence could (if slightly tortuously) be read as "none of Falcon 9's other eight engines were hit [impacted] by debris from the fairing."
[I know that's not you, jkflying, I'm just ranting.]
Did anyone here a call of engine cut-off in the NASA TV feed? I did not. Or a call for a longer burn? Seems the SpaceX team would have made those calls. Of course, they could have on private channels. Seems NASA was more transparent. Also, when I fly I like my pilots to be well dressed and professional. The SpaceX team did not. Maybe that is the SpaceX culture, but I am an old fart and I prefer a much more orderly look.
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This is a fantastic launch and goes to show the safety design.
Dont be too foolish to assume, however, that NASA doesnt also have such designs or such safety mechanisms. Just because their launch has media hype does not discredit NASA.
Great engineering.
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Doctor who?
systemd is Roko's Basilisk.
And don't ride in anything with a Capissen 38 engine, they fall right out of the sky.
We are eternal, all this pain is an illusion.
News to me. Details anyone?
Apollo 6 lost two engines and, AFAIR, suffered partial breakup of the SLA panels covering the lunar module due to pogo.
Apollo 13 lost one engine, which was fortunate because pogo had grown so bad that the Saturn V was on the verge of structural failure. If the engine hadn't failed, they'd have been parachuting back to Earth soon after.
They've launched 4 Falcon 9 rockets. One engine has failed, so that's an observed failure rate of 1/36 or about 3%. The means the odds of 0 or 1 engine failing (a successful launch) is 97.6% and the odds of more than one failing is 2.4% assuming the currently observed rate is representative of the actual rate. 2.4% would be an excellent failure rate for any rocket launch system. In fact, no one has achieved a failure rate that low. And bear in mind this rate includes 3 experimental launches and only one production launch. Of course, a launch failure can be brought about by more than just engine failures, so 2.4% is really a minimum and other factors which haven't yet manifested themselves would add to it.
Space X is saying that this is probably a failure in the aerodynamic structure of the rocket, not the rocket engine itself. If that's the case, the above statistical analysis is invalid because it assumes no interdependency in engine failures. A structural failure could lead to more than one engine failing. It would also be problematic in assessing the future failure rate because the engine configuration is going to change in their 1.1 version. The outer engines will be circularly arranged in future versions while in current versions they're arranged in a square.
Parachuting back to earth would have been *a lot* more comfortable than what they ended up doing.
Apollo 6 (unmanned test, uncontrolled pogo oscillation during first stage, multiple engine failures on 2nd)
http://en.wikipedia.org/wiki/Apollo_6
Apollo 13 (manned launch, pogo oscillations again, shutdown of center first-stage engine.)
http://en.wikipedia.org/wiki/Apollo_13#Launch_incident
All the bare-naked ladies said that.
rewriting history since 2109
It can lose an engine and still make it into orbit! Seriously, how amazing is that?
I supposed they could go with fewer engines, but if they lose one the consequences are greater.
Now they have proof the fail-over systems work. Don't mess with success.
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that was a bit of a bang... lucky the systems were in place to prevent it turning into a disaster...
Also: I've seen comments on the mechanics of dealing with the ejecta. It's simple: when an engine fairing blows, it's no longer travelling at the same speed and direction as the rest of the vehicle. It might explode outwards, but it is, from that point, no longer accelerating upwards. The rest of the vehicle carries on accelerating away from the point of explosion and the wreckage becomes a passenger of Newton. Similarly with the Challenger: you may have noticed from the video of that event that the SRBs kept on going, intact until they splashed down. This is because they were travelling at such a speed and *still accelerating* that the exploding fuel tank and vehicle they were bolted to stopped accelerating and they quickly left the wreckage behind - physics once again provides a simple answer as to why the SRBs didn't turn into giant sticks of dynamite.
Operation Guillotine is in effect.
"Did the primary buffer panel just fall off my gorram ship for no apparent reason?!"
Why would you not want to help a next generation to build on the hard-won successes of the previous? As is said here:
http://en.wikipedia.org/wiki/Social_Credit
"Douglas disagreed with classical economists who divided the factors of production into only land, labour and capital. While Douglas did not deny these factors in production, he believed the "cultural inheritance of society" was the primary factor. Cultural inheritance is defined as the knowledge, technique and processes that have been handed down to us incrementally from the origins of civilization. Consequently, mankind does not have to keep "reinventing the wheel". "We are merely the administrators of that cultural inheritance, and to that extent the cultural inheritance is the property of all of us, without exception.""
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.
The problem the the N1 is that it has a 0-4 record in terms of successful missions, including a major explosion on the launch pad that killed several hundred technicians. It was an amazing rocket, and it is too bad that Sergei Korolev was unable to stay alive long enough to get it working correctly.... but it also never was able to deliver on its promises either.
No, this is not a correct analysis. You have to break it up into all 512 possible outcomes and then calculate the probability for each. So one of the possibilities is that all engines will work, that has a probability of (35/36)^9 or 77.6%. There are 9 possible ways that one engine could fail. Each possibility has a probability of (1/36)^1*(35/36)^8 or 2.2%. If you multiply that by the 9 single engine failure possibilities you get a probability of 20.0% that exactly one engine will fail. So if a successful flight can have either no engines or one engine fail the probability is 77.6% + 20.0% = 97.6%. Does that make sense?
Actually the other engines can definitely be impacted in a catastrophic failure.
So if a successful flight can have either no engines or one engine fail the probability is 77.6% + 20.0% = 97.6%
SpaceX has said that they deliberately turn off 2 engines during flight, and a successful launch could therefore suffer 2 engine failures of this nature.
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If that's the case, you need to add the odds that exactly 2 engines will fail to the above calculation. There are 36 possible configurations where exactly two engines will fail, each has a probability of (1/36)^2*(35/36)^7: 36*(1/36)^2*(35/36)^7 = 2.3% so the overall probability of a successful flight would be 77.6% + 20.0% + 2.3% = 99.9% leaving a truly minuscule probability that you'd ever see a launch failure due to this problem, assuming that one engine failure will not cause failures in additional engines.
That's, uh, kind of my point. If it was in a context where it was completely clear that "impact" meant "affect", it would merely be annoying; the fact that it could conceivably actually mean "impact" in this case is what makes me want to hit the author.
leaving a truly minuscule probability that you'd ever see a launch failure due to this problem, assuming that one engine failure will not cause failures in additional engines.
Which is probably not a good assumption, but I think we have some decent evidence that the correlation between failures of multiple engines is not extremely high.
Gotta say, I'm impressed. And the best part is that a tolerable failure like this one gives them the best chance to identify and fix it -- because one they get more data from a rocket that continued to exist than catastrophically fail and two it won't impact their business model much -- and thus further reduce the risk in the future.
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Using 9 smaller engines allowed them to use the Falcon 1 as a testbed so that they could work the kinks out on a smaller, less expensive rocket then scale up to a much larger rocket without making a lot of changes. It seems to have worked, since they haven't had any total failures during the Falcon 9's development (thereby saving $$$).
It's not as simple as that... I'm skeptical that it would provide 100% of intended performance in all cases, especially for very early failures (e.g. right after liftoff)
Of course, I'm just going by SpaceX's statement that they could have sustained two engine failures "of this nature", which obviously includes it happening late in the boost near when they were going to be turning them off anyway thus the relevance of them mentioning that, versus on the pad.
(In fact, this launch failed to put one of its two payloads into its intended orbit. It's not yet clear whether that was a consequence of the failed engine, but it very well could be.)
It seems to be clear that it is. Due to the failed engine they had to alter the trajectory. Because the new trajectory was not able to be checked for safety wrt the ISS in time, they were not authorized for the planned second burn of the second stage, which still could have in theory delivered the Orbcomm satellite to the proper orbit.
So, the failure definitely affected the success of the mission, but not because of the rocket's capability to recover from the failure, just wise precautions. Being demonstrably able to finish the primary mission after that failure, and theoretically being able to handle two of this kind, is pretty impressive. Of course no failing engines will be the situation they strive for in the future. :)
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