SpaceX F9 : Starlink 6 (v1.0 L5) : Mar. 18, 2020 - Discussion

[wardy89]

F9 uses 3 engines for entry burn, if one of the engines that shut down on ascent was one of these 3 I don't think we'd see an entry burn attempt, and then if one of the engines used for landing failed during the entry burn then it might not even make it to the surface.

I am not so sure. The recovery burns may well have different engine parameters than for ascent, It could well be possible for an engine that shuts down on accent can try and fire up again during the recovery because of looser engine perimeters. And what you are seeing is during entry burn is the same engine initially firing up then shutting down again, but having more of an effect due to their only being 3 engines running.

[MKrob89]

as it looks like the off nominal engine failed, it seems likely that the events are connected, but a failed turbine blade doesnt match with that. Perhaps the turbopump or engine was damaged by an overstress event during the aborted launch, for example if there was a pressure sensor malfunction that caused excessive turbopump speed.

[envy887]

Everybody keeps saying "engine failure". Isn't it possible that the engine was intentionally shut down because of a slightly off nominal condition, since other engines could just throttle up to make up  the difference? Meaning they might even have used it for the entry burn since there was nothing to lose?

I don't think they would shut down an engine out of an abundance of caution. If the engine controller shut down the engine without an actual failure, it was probably because it thought the engine was about to start spreading pieces of itself all over the Atlantic.

That might not preclude them from starting that same engine up again during reentry, depending on how hard it is to do the entry burn with only 2 engines. The video sure looks like there is more than 1 engine running during the entry burn, but it's hard to tell if it's 2 or 3.

[whitelancer64]

I know SpaceX is a private company, but I'm disappointed at the lack of information during the live broadcast.  Not because I think they "owe" it to us or anything, but it's just that I'm interested in what's happening while it's happening.  The people who talk on the stream are obviously knowledgable and highly skilled.  But they are acting as PR people; not scientists.

I know that the people actually handling the situations are too busy to be dealing with viewers.  But if you are going to have dedicated people to announce the status, and they are skilled enough to understand what's going on, I wish they would actually report the status.  The launchpad abort, although an unfortunate mistake, leads me to believe they are reading from a script and not looking at actual telemetry.

Sorry to vent about this.  Again, I don't feel like they owe it to us and they're a private company.  I just wish it was different.

Obviously they are reading from a script, or at least have outlines to refer to. In many cases they are presenting large blocks of information at a time. As knowledgeable as they are, you'd at least want that as you are doing a presentation to a wide audience, so you don't want to flub up if at all possible.

They did report the status of the 1st stage when they knew it.

Anyone would say "liftoff" at the time of liftoff. It aborted right at T 0. They also said "disregard" right afterward, which wouldn't be in a script.

[kevinof]

You're right, they don't owe you anything. Get serious please.

The people in front of the cameras are not sitting in front of the telemetry screens, looking at the vehicle state. They are giving a presentation on the flight to an audience and we're thankful for it. Meanwhile, in the control rooms there are teams saying, Oh crap, I think we've just lost an engine, let's figure out where we are and what to to.

They owe you nothing. And you might thank Elon for tweeting what happened 15 minutes after the flight. Had this been another company we wouldn't hear anything for months.
 
Come on. 

I know SpaceX is a private company, but I'm disappointed at the lack of information during the live broadcast.  Not because I think they "owe" it to us or anything, but it's just that I'm interested in what's happening while it's happening.  The people who talk on the stream are obviously knowledgable and highly skilled.  But they are acting as PR people; not scientists.

I know that the people actually handling the situations are too busy to be dealing with viewers.  But if you are going to have dedicated people to announce the status, and they are skilled enough to understand what's going on, I wish they would actually report the status.  The launchpad abort, although an unfortunate mistake, leads me to believe they are reading from a script and not looking at actual telemetry.

Sorry to vent about this.  Again, I don't feel like they owe it to us and they're a private company.  I just wish it was different.

[daedalus1]

Hopefully the failure mode for that engine was relatively simple otherwise there might be some effect to the DM2 schedule. I suppose NASA will be interested to know what went on as well.


Given how many of these have flown and how much firing time has been amassed this was probably due to either wear and tear or a manufacturing defect specific to that engine.

Considering that the Atlas engines that launch the Starliner end up in the Atlantic after one use, why would this delay Dragon 2 launch? This is the 5th launch of these engines and Dragon will not be on a 5th used booster. Talk about one rule for one...!

An engine failed on ascent.  That has to be looked at.

Yes it will be by SpaceX, NASA shouldn't be a part of the equation.

[gaballard]

I know SpaceX is a private company, but I'm disappointed at the lack of information during the live broadcast.  Not because I think they "owe" it to us or anything, but it's just that I'm interested in what's happening while it's happening.  The people who talk on the stream are obviously knowledgable and highly skilled.  But they are acting as PR people; not scientists.

I know that the people actually handling the situations are too busy to be dealing with viewers.  But if you are going to have dedicated people to announce the status, and they are skilled enough to understand what's going on, I wish they would actually report the status.  The launchpad abort, although an unfortunate mistake, leads me to believe they are reading from a script and not looking at actual telemetry.

Sorry to vent about this.  Again, I don't feel like they owe it to us and they're a private company.  I just wish it was different.

Remember that Ariane launch that failed last year/the year before? There was nothing. Silence. Still not even sure if we ever got the whole story.

You should try following other launch providers along with SpaceX. It'll make you realize how much info SpaceX gives us and how lucky we are for it.

[ulm_atms]

Hopefully the failure mode for that engine was relatively simple otherwise there might be some effect to the DM2 schedule. I suppose NASA will be interested to know what went on as well.


Given how many of these have flown and how much firing time has been amassed this was probably due to either wear and tear or a manufacturing defect specific to that engine.

Considering that the Atlas engines that launch the Starliner end up in the Atlantic after one use, why would this delay Dragon 2 launch? This is the 5th launch of these engines and Dragon will not be on a 5th used booster. Talk about one rule for one...!

An engine failed on ascent.  That has to be looked at.

Yes it will be by SpaceX, NASA shouldn't be a part of the equation.

It's on a rocket that will carry NASA crew....it will very much be looked at by NASA.

[daedalus1]

So after Atlas's first flight NASA would have to go fishing. You are missing the point of my comment. It worked pefectly on its first flight and Dragon will be lauched on a new booster.

[wannamoonbase]

Hopefully the failure mode for that engine was relatively simple otherwise there might be some effect to the DM2 schedule. I suppose NASA will be interested to know what went on as well.


Given how many of these have flown and how much firing time has been amassed this was probably due to either wear and tear or a manufacturing defect specific to that engine.

Considering that the Atlas engines that launch the Starliner end up in the Atlantic after one use, why would this delay Dragon 2 launch? This is the 5th launch of these engines and Dragon will not be on a 5th used booster. Talk about one rule for one...!

An engine failed on ascent.  That has to be looked at.

Yes it will be by SpaceX, NASA shouldn't be a part of the equation.

Uh yeah NASA should be involved.

Maybe it's a reuse issue.  But you're going to look at it to make sure it's understood what happened in the most exacting detail possible.

SpaceX wants this too.  Every failure needs to be understood and it's a learning opportunity to improve the Merlin.

[ugordan]

I'm not confident enough to post this on twitter yet, but I think there might have been a second engine failure during the entry burn, and that killed the chance of landing.
 
At entry burn there's a change in the exhaust pattern accompanied by what looks like a bump, then the  camera got fogged up with visible drops of liquid, which I think is unburned fuel expelled during an engine failure.

F9 uses 3 engines for entry burn, if one of the engines that shut down on ascent was one of these 3 I don't think we'd see an entry burn attempt, and then if one of the engines used for landing failed during the entry burn then it might not even make it to the surface.

I'm not sure I'd agree with a 2nd engine failure during the entry burn. I'm of the opinion that this entry burn looked different than the others precisely because loss of thrust during ascent, the MECO velocity condition was achieved later than expected, probably higher than expected so the ballistic IIP carried it further downrange from the ASDS than desired, outside of the reachable envelope. The fogging up of the camera could be a result of the fact the stage tried to orient to a different thrust vector during reentry burn to get it back on desired impact point so the reentry exhaust flow that typically escapes the camera did not do it this time as the AoA was different.

I'll admit that the 1-3 engine ignition was missing that signature interference pattern and on the previous Starlink launch the feed cut out just at that same moment so it's hard to tell if one of the outer engines that is used during reentry was the one that failed.

Someone on reddit posted an analysis of ascent acceleration from the webcast data and it looks like the other engines did not throttle up virtually immediately to recover the expected acceleration profile (as by that point all the engines were very, very likely running G-limiting throttle down so they could have done it, in principle). If so, that would only make matters worse for a ballistic IIP targeting the general area of ASDS.

[baldusi]

Next flight is actually CONAE's SAOCOM-1B mission. Then comes another Starlink. It will be interesting to see how those schedules hold up.

[ulm_atms]

So after Atlas's first flight NASA would have to go fishing. You are missing the point of my comment. It worked pefectly on its first flight and Dragon will be lauched on a new booster.

It failed when it wasn't supposed to.  Was it due to age?  refurb issue?  handling issue?  Something that could break the first time and SpaceX has just been lucky to date?  Who knows.  But to write:

NASA shouldn't be a part of the equation.

is just a big fat "not going to happen...NASA will be involved...full stop."

[gaballard]

Seems like it'll be a pretty straightforward sequence of events... NASA will want to know if the issue was one that could affect the first flight of new boosters, or if it's just a result of fatigue from being flown five times. If it's the latter, I don't see it having any impact on Commercial Crew (it may put a limit on NASA's use of flown boosters in the future, e.g. none with > n flights). If it's the former, well... we're already all buckling up and waiting with this pandemic anyway... just one more thing to wait on.

[daedalus1]

So after Atlas's first flight NASA would have to go fishing. You are missing the point of my comment. It worked pefectly on its first flight and Dragon will be lauched on a new booster.

It failed when it wasn't supposed to.  Was it due to age?  refurb issue?  handling issue?  Something that could break the first time and SpaceX has just been lucky to date?  Who knows.  But to write:

NASA shouldn't be a part of the equation.

is just a big fat "not going to happen...NASA will be involved...full stop."

I have no idea if NASA will be involved or not, it is just my opinion that they shouldn't be. And I've given my reasons for that opinion.

[LouScheffer]

I know SpaceX is a private company, but I'm disappointed at the lack of information during the live broadcast.  Not because I think they "owe" it to us or anything, but it's just that I'm interested in what's happening while it's happening.  The people who talk on the stream are obviously knowledgable and highly skilled.  But they are acting as PR people; not scientists.

I know that the people actually handling the situations are too busy to be dealing with viewers.  But if you are going to have dedicated people to announce the status, and they are skilled enough to understand what's going on, I wish they would actually report the status.  The launchpad abort, although an unfortunate mistake, leads me to believe they are reading from a script and not looking at actual telemetry.

Have you ever given a public talk?  If you are any good at it, you are thinking of what's next while you are speaking.  So you say "On the next slide we see" as you are flipping the slide, not flip the slide, wait to see that it's what you expect, then speak.  When things go correctly, it make a much more fluid and professional presentation.  But when things go wrong (the next slide is not what you expect, the rocket does not lift off, etc.) then you say "Never mind" and correct yourself.   This is exactly what we saw as "3..2..1 Liftoff .. Disregard".  It's a sign of professionalism during presentation, not a bug.

This was much better than the Ariane launch when they kept on the normal announcement timeline for *minutes* as the rocket was heading off in the wrong direction, going out of contact, etc.

Also, when the commentary is actually mission critical, the protocol is not to anticipate.  So if the pilot says "Landing gear?" the copilot is not supposed to say "check" or "three green" or whatever until they have actually observed the event.   That's appropriate for a checklist but not a webcast.

[JamesH65]

I know SpaceX is a private company, but I'm disappointed at the lack of information during the live broadcast.  Not because I think they "owe" it to us or anything, but it's just that I'm interested in what's happening while it's happening.  The people who talk on the stream are obviously knowledgable and highly skilled.  But they are acting as PR people; not scientists.

I know that the people actually handling the situations are too busy to be dealing with viewers.  But if you are going to have dedicated people to announce the status, and they are skilled enough to understand what's going on, I wish they would actually report the status.  The launchpad abort, although an unfortunate mistake, leads me to believe they are reading from a script and not looking at actual telemetry.

Sorry to vent about this.  Again, I don't feel like they owe it to us and they're a private company.  I just wish it was different.

You say they don't owe you anything, then go on to complain that they should have given you more than you got. Odd. Are you aware of the dissonance in that statement.

[aviators99]

You're right, they don't owe you anything. Get serious please.

Thanks for agreeing with me.   I understand how people are really quick to jump to their defense, because  I'm a amazing people too.  I'm simply expressing that I wish I could have direct access to NET or something similar.  It would be fun and nice.  Sorry to offend.

[aviators99]

I know SpaceX is a private company, but I'm disappointed at the lack of information during the live broadcast.  Not because I think they "owe" it to us or anything, but it's just that I'm interested in what's happening while it's happening.  The people who talk on the stream are obviously knowledgable and highly skilled.  But they are acting as PR people; not scientists.

I know that the people actually handling the situations are too busy to be dealing with viewers.  But if you are going to have dedicated people to announce the status, and they are skilled enough to understand what's going on, I wish they would actually report the status.  The launchpad abort, although an unfortunate mistake, leads me to believe they are reading from a script and not looking at actual telemetry.

Sorry to vent about this.  Again, I don't feel like they owe it to us and they're a private company.  I just wish it was different.

You say they don't owe you anything, then go on to complain that they should have given you more than you got. Odd. Are you aware of the dissonance in that statement.

Never once complained.  I was just saying what I wished.

[Lars-J]

I'm not confident enough to post this on twitter yet, but I think there might have been a second engine failure during the entry burn, and that killed the chance of landing.
 
At entry burn there's a change in the exhaust pattern accompanied by what looks like a bump, then the  camera got fogged up with visible drops of liquid, which I think is unburned fuel expelled during an engine failure.

F9 uses 3 engines for entry burn, if one of the engines that shut down on ascent was one of these 3 I don't think we'd see an entry burn attempt, and then if one of the engines used for landing failed during the entry burn then it might not even make it to the surface.

Yes the braking/entry burn startup looked different. It is possible that the engine that failed was one of the three engines needed for this burn, so we only got a 2-engine braking burn, which could explain the apparent yaw and off-axis thrust before stabilizing, and the movement after cutoff. And that the speed was not reduced sufficiently, leading to loss of stage.

But I'm just speculating. The primary missing succeeded, yay for engine out capability.  (first time this has been demonstrated post F9v1.0)