Space News has the story. Some have said that this proves that Fragola was right, but that’s nonsense. He tried to create a rumor that the stage blew up. SpaceX had never denied that there was an engine problem, and they apparently provided the information quickly to everyone that needed to know (i.e., NASA and the FAA). They aren’t under any obligation to air all their laundry publicly.
12 thoughts on “The SpaceX Engine “Anomaly””
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Fuel mix and overheating seams like a controllable/fixable problem to me. Perfection isn’t achievable (if you can’t achieve something it may take some time, eh?)
So they will do more redesign. Merlin E?
Guys this was during a shutdown, not a premature shutdown, a scheduled shutdown.
The Gas generator runs fuel rich to keep the gas temperature down.
It sounds like the gas generator shutdown when ox rich, too much oxygen could spike the temperature significantly, and this temp spilke could have damaged the turbo pump. This fault during shutdown may destroy the turbopump, but the 1st stage motors do not restart so
on the first stage this is a 100% non issue. When they start reusing the 1st stage, or relighting the 1st stage for some kind of flyback for recovery it could become an issue, as of now its not an issue.
To me the far more interesting question is if the fault is in the components that are common to the 2nd stage merlin….
My guess is that the turbopump and gas generator on the 2nd stage is very similar, if not identical, to the units on the 1st stage. The primary difference on the 2nd stage is in the chamber expansion ratio.
Since the 2nd stage is required to relight at least one time to do a second burn, this failure during the first shutdown of the 2nd stage
could lead to a mission failure.
I believe that its possible, but less efficient, to do orbit insertion with
a single burn and no relight. As I think the F9 dragon combination has significant performance margin adjusting the trajectory to not require a 2nd stage relight might be a wise decision for the next flight.
As the next flight is supposed to go to ISS and also deliver significant paying secondary payloads to other orbits, this particular failure probably really complicates the ISS hazard avoidance negotiations.
The dragon has some native propulsion performance so maybe the dragon can do its own secondary burn and the 2nd stage restart is only needed to get the secondary payloads into the proper orbit.
Paul, direct insertion is precisely the method they plan on using for Dragons.
You bring up a good point about the MVac pump, though.
When they start reusing the 1st stage, or relighting the 1st stage for some kind of flyback for recovery it could become an issue, as of now its not an issue.
I don’t have the science to this, but based on what was actually “admitted” vs. the guy going “GOTCHA!” I read it as “so they might lose reusability in the first stage.”
I had to read it a couple times to piece out which quotes were admissions, and which quotes were from the guy who was spreading rumors. Turned out most of the “bad” info, was just a requote of the cat spreading rumors.
I wonder if this is related to the anomalous restart of the MVac on the first flight.
>I wonder if this is related to the anomalous restart of the MVac on the first flight.
I’d forgotten about that.
It could easily be related as all the pieces fit….
The first flight failure could also be something completely different, a failure of propellant settling or ….?
I remember one possible cause mentioned for a failed restart on F9-01 was that the stage cold gas ACS ran out before killing the severe roll of the stage after SECO-1. With propellant not being settled properly before ignition, MVac could have ingested gas instead of liquid. Note the stage was seen slowly spinning over Australia after the time of ignition suggesting this could have been the root cause.
Back to the issue at hand here, here’s a snippet of what SpaceX PAO said in one blog’s comments:
To improve the potential of reusing engines, and to make the shutdown process as predictable as possible, SpaceX has made a small change so that the engines will run out oxidizer before running out of fuel.
This suggests it wasn’t an inherent nature of the Merlin, but rather the sideeffect of running out of RP-1 first. One is then lead to assume that a guidance-commanded MVac shutdown would not be affected by this issue.
Seems that an engine anamoly that doesn’t lead to the cargo in the drink or in little pieces is a feature, not a bug.
SpaceX is being very nice here. If these rumors were about a power station, GE would be suing every paper that published them.. and there would be no “clarifying comments” until it went to court, if ever.
I think SpaceX handled this badly. What they should have done: threatened lawsuit on Space News, demand they retract the story, and not provide them a single scrap of additional information. I know that seems like hardball but you watch what happens when the next rumor starts up.
There’s freedom of the press in the US, but it doesn’t provide you carte blanche to print falsehoods.
Interesting SpaceX had to sue Fragola, his “rumor” sounds like the sort of paranoid crap one sees in forum comments from Gaetano.
Paul, that is very interesting.
I imagine that the 9-engine cluster of the Falcon 9 1st-stage is a challenging thermal environment. I bet the anomaly was with the central engine of the cluster.
If this is true, I doubt a similar problem will arise with the 2nd-stage vacuum optimized Merlin, since it operates in isolation.
Would removing the central engine be fate (F8?)