Author Topic: SpaceX Acknowledges Falcon 9 Engine Anomaly  (Read 45475 times)

Offline RocketEconomist327

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SpaceX Acknowledges Falcon 9 Engine Anomaly
« on: 09/10/2011 12:22 am »
People call me a SpaceXer fanboy.  I am not.  I believe in commercial space and think it is the way to go.  That being said, here is the truth:

http://www.spacenews.com/civil/spacex-acknowledges-falcon-engine-anomaly-during-latest-launch.html

Quote
WASHINGTON -- Space Exploration Technologies (SpaceX) Corp. acknowledged that its Falcon 9 rocket experienced an engine anomaly during its December launch of the company’s reusable Dragon space capsule.

VR
RE327
« Last Edit: 09/10/2011 02:33 am by Chris Bergin »
You can talk about all the great things you can do, or want to do, in space; but unless the rocket scientists get a sound understanding of economics (and quickly), the US space program will never achieve the greatness it should.

Putting my money where my mouth is.

Offline MarekCyzio

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #1 on: 09/10/2011 12:23 am »
This bothers me:
Quote
“There was no explanation or root cause analysis or corrective action for this particular anomaly,” Daniel said Sept. 9 during the public meeting.

Offline kevin-rf

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #2 on: 09/10/2011 12:39 am »
Question, in the Falcon 9 first stage, do they run to depletion and does this mean they ran out of fuel before oxidizer and did not shutdown fast enough after fuel depletion was detected?

So do they need to tune the shutdown algorithm or relocate the fuel out sensor(s)?

I give it 3...2...1.... till someone decides the Oxidizer rich shutdown temperature spike was why the first stage did not make it back in one piece... 
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Offline neilh

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #3 on: 09/10/2011 12:40 am »
This bothers me:
Quote
“There was no explanation or root cause analysis or corrective action for this particular anomaly,” Daniel said Sept. 9 during the public meeting.

Keep in mind that Daniel's from the company that SpaceX sued for allegedly spreading defamatory rumors about this.
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Offline edkyle99

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #4 on: 09/10/2011 01:01 am »
People call me a SpaceXer fanboy.  I am not.  I believe in commercial space and think it is the way to go.  That being said, here is the truth:

http://www.spacenews.com/civil/spacex-acknowledges-falcon-engine-anomaly-during-latest-launch.html

Quote
WASHINGTON -- Space Exploration Technologies (SpaceX) Corp. acknowledged that its Falcon 9 rocket experienced an engine anomaly during its December launch of the company’s reusable Dragon space capsule.

Which engine?  When?  Where in the flight profile?  This story is missing three or four of the five "W"s.  (Who, what, when, where, why).

 - Ed Kyle

Offline ArbitraryConstant

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #5 on: 09/10/2011 01:09 am »
Does that mean engine out was given a surprise test?

Offline notsorandom

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #6 on: 09/10/2011 01:17 am »
Question, in the Falcon 9 first stage, do they run to depletion and does this mean they ran out of fuel before oxidizer and did not shutdown fast enough after fuel depletion was detected?

So do they need to tune the shutdown algorithm or relocate the fuel out sensor(s)?

I give it 3...2...1.... till someone decides the Oxidizer rich shutdown temperature spike was why the first stage did not make it back in one piece... 
I'm sure there will be people who say this. However, SpaceX has been pretty honest as to why they are having trouble recovering their stages. As Elon said its basically doing a belly flop. The first stage is coming in very fast and at an angle that doesn't give it much time to slow down in the upper atmosphere. Its also faster and less robust then a Shuttle SRB.

Offline Antares

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #7 on: 09/10/2011 02:03 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.

Daniels and Fragola have no idea what SpaceX told NASA, either way.  They just know that C/CA wasn't presented to ASAP.

Barkeep!  Back to my beer.
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Offline kevin-rf

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #8 on: 09/10/2011 02:14 am »
Does that mean engine out was given a surprise test?

Where does it say engine out? It says O2 rich shutdown, there are two shutdown events. The first event shuts down two engines, the second shuts down the remaining seven. They never said anything about an engine failing, or shutting down early.

Between the lines it sounds to me like they ran the stage to depletion and the propellant depleted before they had fully shutdown the final seven engines. Like I asked earlier, bad shutdown program, or is the depletion sensor not far enough upstream to get all seven shutdown before the fuel is depleted.

But like Ed said, the full set of W's are missing.

I think someone should hit the mod button and have Chris email SpaceX's POA for clarification on the W's...
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Offline Jason Sole

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #9 on: 09/10/2011 02:22 am »
So SpaceX lied when they said there wasn't an anomaly.

Great! Nice to see my NASA tax dollars being spent on companies which act in this way.

Offline Chris Bergin

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #10 on: 09/10/2011 02:35 am »
Behave yourself Jason. Very vauge on the details, but I doubt we'll ever get to hear any more. Bound to be prop restricted.

I personally miss the absolute transparency of Shuttle. When those ladies had a problem, you got to know about it, and you respected the get-wells.
« Last Edit: 09/10/2011 02:37 am by Chris Bergin »

Offline Ronsmytheiii

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #11 on: 09/10/2011 03:05 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.

Yes just like the O-ring on STS-51C or the foam liberation on STS-112 did not result in a LOM for those respective missions.

This is a big deal.....
« Last Edit: 09/10/2011 03:16 am by Ronsmytheiii »

Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #12 on: 09/10/2011 03:31 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.

Yes just like the O-ring on STS-51C or the foam liberation on STS-112 did not result in a LOM for those respective missions.

This is a big deal.....

No, it isn't and it isn't like the foam or Oring.  It happened on a test flight, which is supposed to find bugs like this. This is just like the problem on the first Delta IV heavy.  yes, it is a problem, but it is being worked and all the information was provided to NASA quickly.

Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #13 on: 09/10/2011 03:32 am »
So SpaceX lied when they said there wasn't an anomaly.

Great! Nice to see my NASA tax dollars being spent on companies which act in this way.

No, big deal. NASA was fully aware.

Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #14 on: 09/10/2011 03:34 am »
Many of us had to bite our tongues about this.  We don't get to tell you about all the issues on each ELV flight.

Offline spacetraveler

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #15 on: 09/10/2011 03:41 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.

Yes just like the O-ring on STS-51C or the foam liberation on STS-112 did not result in a LOM for those respective missions.

This is a big deal.....

No, it isn't and it isn't like the foam or Oring.  It happened on a test flight, which is supposed to find bugs like this. This is just like the problem on the first Delta IV heavy.  yes, it is a problem, but it is being worked and all the information was provided to NASA quickly.

So then, are you saying that Charles Daniel lied in the statement quoted above?

It would seem that that statement is contradictory.

Personally I hope that statement is wrong, as I would like to believe that SpaceX was aware of and working the problem, which would seem to be basic due diligence.
« Last Edit: 09/10/2011 03:44 am by spacetraveler »

Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #16 on: 09/10/2011 03:44 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.

Yes just like the O-ring on STS-51C or the foam liberation on STS-112 did not result in a LOM for those respective missions.

This is a big deal.....

No, it isn't and it isn't like the foam or Oring.  It happened on a test flight, which is supposed to find bugs like this. This is just like the problem on the first Delta IV heavy.  yes, it is a problem, but it is being worked and all the information was provided to NASA quickly.

So then, are you saying that Charles Daniel lied in the statement quoted above?

It would seem that that statement is contradictory.

Lied where?  ASAP is not NASA.

Offline spacetraveler

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #17 on: 09/10/2011 03:47 am »
He stated in the linked article that there was no analysis or corrective action that had taken place for this issue, you stated that it "is being worked".

It would seem to me that both statements cannot be true.

Online docmordrid

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #18 on: 09/10/2011 03:49 am »
I'm sure Jim will correct me if I'm wrong, but this doesn't sound any more "important" than the mini-roll F9-1 did on liftoff. NBFD.
DM

Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #19 on: 09/10/2011 04:06 am »
He stated in the linked article that there was no analysis or corrective action that had taken place for this issue, you stated that it "is being worked".

It would seem to me that both statements cannot be true.

Read the article.  What it is saying is that Spacex acknowledged the issue.  It says no more.  It doesn't say what or what they are not doing.

Charles Daniel is only saying that they didn't provide additional data.

“There was no explanation or root cause analysis or corrective action for this particular anomaly,”

It is just a context issue in the article.
« Last Edit: 09/10/2011 04:14 am by Jim »

Offline Antares

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #20 on: 09/10/2011 04:07 am »
Daniels said, "There was no explanation or root cause analysis or corrective action for this event." He only knows and has purview to what was presented to ASAP. We can't know one way or the other what NASA knew and when. As Jim said, ASAP /= NASA.
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Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #21 on: 09/10/2011 04:13 am »
I'm sure Jim will correct me if I'm wrong, but this doesn't sound any more "important" than the mini-roll F9-1 did on liftoff. NBFD.

yes, it is just an additional feature that will be eliminated from future vehicles.

And I am not on the bandwagon.  They still have a long way to go.

 Every space launch is a near miss, because the margins are so tight.  And with a new vehicle, the issue is to make your vehicle can operate at the bounds of the margins in the various systems.

Offline Antares

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #22 on: 09/10/2011 04:16 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.
Yes just like the O-ring on STS-51C or the foam liberation on STS-112 did not result in a LOM for those respective missions.

This is a big deal.....
No, it isn't and it isn't like the foam or Oring.  It happened on a test flight, which is supposed to find bugs like this. This is just like the problem on the first Delta IV heavy.  yes, it is a problem, but it is being worked and all the information was provided to NASA quickly.

Depletion settings, if that's (IMEO) what it was, are the simplest fix. A constant in a software load. Granted, a single wrong constant can cause LOM, but as usual with proprietary vehicles none of us can know the whole story on the outside. And those on the inside can't talk about it - only the owners of the data. And even they are limited by eyetar.
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline Chris Bergin

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #23 on: 09/10/2011 04:26 am »
Good pre-emptive firefighting on this thread from Antares and Jim. Happened to see a thread on another site which is currently acting like the sky is falling and people should be sent to the Hague. They don't have a Jim or Antares ;D

Offline Diagoras

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #24 on: 09/10/2011 04:38 am »
Yawn, a medium to major anomaly that didn't cause LOM on an early flight.  BFD.

Daniels and Fragola have no idea what SpaceX told NASA, either way.  They just know that C/CA wasn't presented to ASAP.

Barkeep!  Back to my beer.

Quote
No, it isn't and it isn't like the foam or Oring.  It happened on a test flight, which is supposed to find bugs like this. This is just like the problem on the first Delta IV heavy.  yes, it is a problem, but it is being worked and all the information was provided to NASA quickly.

Aaaand the two big dogs have weighed in and agreed. That's good enough for me.
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Offline Lars_J

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #25 on: 09/10/2011 05:04 am »
Since there was no LOM, nor an early engine shut down despite the hotter than expected combustion at shutdown (?), at least that should give some bonus for the Merlin engines being able to handle it.

There are probably many other smaller issues that were noted during the last flight that we have no idea about. As long as SpaceX and NASA are aware, and improvements are being made, that's what matters.

From what we have been made public, there seems to have been tweaks to the F9 tanks and probably other hardware since the last flight. I'm sure software has been updated as well.


Offline neilh

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #26 on: 09/10/2011 05:37 am »
I'm wondering how many days it'll be before there's an article on this in the WSJ by Andy Pasztor with a headline like "SpaceX Launch Failure Threatens White House's NASA Outsourcing Plan."
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Offline Jason1701

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #27 on: 09/10/2011 06:04 am »
If only all flights were so successful that all people could nitpick was the mixture ratio in an engine upon shutdown.

Offline iamlucky13

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #28 on: 09/10/2011 06:32 am »
I don't recall at the moment - was there an orbit target published for this mission, and did they hit it within a reasonable margin?

Sorry...I'm a little too lazy at the moment to dig through the huge post-flight thread, and not very good at getting the results I'm looking for using the search.

The only thing concrete I see is Bowersox's saying there was an oxygen-rich shut down.

I don't see any indication of whether this was premature or nominal timing, but kevin-rf and Antares' speculation about mix makes sense.

Excess oxygen at shutdown in a hot turbopump is not a good condition for re-usability, but I'm having a hard time envisioning the LOM pathway.

Premature shutdown would be a little more concerning, but SpaceX insists they have margin for that.


I just went back and watched the highlights video again. There's a slight flash a second before the PAO reports the first two engines shut down, then MECO...it looks pretty nominal to me. The first stage very clearly did not explode.


I missed the news about the law suit previously. Why the heck was Mr. Fragola telling NASA in June that he had reason to believe the first stage exploded even though video showing the contrary had been in the public domain since the previous December?

Offline Pedantic Twit

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #29 on: 09/10/2011 07:17 am »
I don't recall at the moment - was there an orbit target published for this mission, and did they hit it within a reasonable margin?

Sorry...I'm a little too lazy at the moment to dig through the huge post-flight thread, and not very good at getting the results I'm looking for using the search.

From the COTS Flight 1 Press Kit: 300x300 km
From the live coverage thread: 288x301 km
The user guide notes to expect ±10 km on perigee and apogee.
« Last Edit: 09/10/2011 07:40 am by Pedantic Twit »

Offline edkyle99

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #30 on: 09/10/2011 03:12 pm »
I don't recall at the moment - was there an orbit target published for this mission, and did they hit it within a reasonable margin?

Sorry...I'm a little too lazy at the moment to dig through the huge post-flight thread, and not very good at getting the results I'm looking for using the search.

From the COTS Flight 1 Press Kit: 300x300 km
From the live coverage thread: 288x301 km
The user guide notes to expect ±10 km on perigee and apogee.

The second stage had excess propellant (it performed a relatively long second burn) so the LEO orbit should not have been affected by a first stage anomaly. 

 - Ed Kyle

Offline Diagoras

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #31 on: 09/10/2011 03:32 pm »
Good pre-emptive firefighting on this thread from Antares and Jim. Happened to see a thread on another site which is currently acting like the sky is falling and people should be sent to the Hague. They don't have a Jim or Antares ;D

Ooh, who? Name names!  ;D
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Offline Chris Bergin

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #32 on: 09/10/2011 08:45 pm »
Not giving attention to armwaving ;)

Offline Diagoras

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #33 on: 09/10/2011 09:49 pm »
Not giving attention to armwaving ;)

And there goes may plan to log on to that site and scream "WIIIIIIIIIIITCH!" to cause further panic.

Phooey.
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Offline Downix

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #34 on: 09/10/2011 10:42 pm »
A second test flight and there were anomalies which could be compensated for, nothing unusual here.  In fact, it is common to find such issues on many launches.  The only concern I have is the long delay before acknowledgement, and even the very aggressive attempts to silence those who brought it up.  We expect first flight issues, that's the nature of any industry.  Shoot, we have airplanes with flight anomalies almost constantly.  I hope that this was overreaction from SpaceX, and does not happen again.  Not the anomaly, but the apparent attempt to cover it up.
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Offline Prober

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #35 on: 09/10/2011 11:11 pm »
Many of us had to bite our tongues about this.  We don't get to tell you about all the issues on each ELV flight.

+ 2 points to everyone to kept this quiet.   Good to see professional people are still around and can be trusted.
 
 
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Offline RocketEconomist327

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #36 on: 09/10/2011 11:12 pm »
Dear Lord.  I have never seen the response from Jim and Antares like that before.  It was like a pack of rhinos in the dessert when they spot a fire...

Glad to see this.

I would just add, from how Jim described it, just because SpaceX doesn't tell "da media" about problems doesn't mean that they did not tell the appropriate officials in NASA.

Clearly, the good folks at NASA can keep a sekrit.

VR
RE327
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Offline Prober

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #37 on: 09/10/2011 11:20 pm »
I'm sure Jim will correct me if I'm wrong, but this doesn't sound any more "important" than the mini-roll F9-1 did on liftoff. NBFD.

yes, it is just an additional feature that will be eliminated from future vehicles.

And I am not on the bandwagon.  They still have a long way to go.

 Every space launch is a near miss, because the margins are so tight.  And with a new vehicle, the issue is to make your vehicle can operate at the bounds of the margins in the various systems.

The pieces all fit in the stories.  IMHO, NASA handled this about as well as the engine problems on the engine tests for Orbital. 
 
I was kinda hard on SpaceX for not launching a Cots test this month.  Clearly they weren't ready and doing some rework and all is fine.
 
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Offline Prober

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #38 on: 09/10/2011 11:29 pm »
I'm wondering how many days it'll be before there's an article on this in the WSJ by Andy Pasztor with a headline like "SpaceX Launch Failure Threatens White House's NASA Outsourcing Plan."

Thats not an issue, its all out in the open.   The real problem might be with Congress if/should/when they have been told or not.
 
Not an issue for lower NASA management, top brass?
 
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Offline edkyle99

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #39 on: 09/11/2011 12:34 am »
The only concern I have is the long delay before acknowledgement, and even the very aggressive attempts to silence those who brought it up. 

As I understand it, they filed suit against an industry insider who made untrue (still untrue) accusations to NASA officials.  The rest of it is not a "cover up", but standard corporate confidentiality agreement stuff.

Still, SpaceX has kept a lot of its troubles out of the public eye.  We've heard hints of a long-ago Merlin shredding itself on a test stand, for example, but never seen photos or videos.  We've never seen photos or videos of the Falcon 1 that imploded on the launch pad and never flew.  We've never seen the Falcon 1 Flight 1 crash and explosion video - something that has to have involved more than just SpaceX  - for many years now - since it happened on a U.S. range.  Etc.   

I understand this is their stuff and they can keep it under the rug if they want, but I'm not a fan of keeping important facts in file cabinets.  I want historians to know the real story - early failures and subsequent successes.  Someone send something to Wikileaks already!

 - Ed Kyle
« Last Edit: 09/11/2011 12:37 am by edkyle99 »

Offline kevin-rf

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #40 on: 09/11/2011 12:56 am »
I understand this is their stuff and they can keep it under the rug if they want, but I'm not a fan of keeping important facts in file cabinets.

There is a difference between acknowledging an event happened and providing HD video of the event.

I am curious with the LOX rich shutdown if this is something they immediately knew about, or picked up after they did post flight analysis of the flight. Unlike a crushed tank, or a failed launch, with no stage recovery, the only clues to this will be in the telemetry... They have to identify an issue, determine what happened, the impact, and then a corrective action (if needed), then test the corrective action.

btw. Doesn't imploded imply a violent crushing and shredding of the tank? The crushed tank was more along the lines of a slow crushing of the tank as the tank was drained.
« Last Edit: 09/11/2011 12:59 am by kevin-rf »
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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #41 on: 09/11/2011 02:13 am »
I am curious with the LOX rich shutdown if this is something they immediately knew about, or picked up after they did post flight analysis of the flight. Unlike a crushed tank, or a failed launch, with no stage recovery, the only clues to this will be in the telemetry... They have to identify an issue, determine what happened, the impact, and then a corrective action (if needed), then test the corrective action.

Ken said, "So because of that, when you get that mixture change happening, the temperatures can go up higher than you want inside the gas generator."  Bowersox added that "those temperatures could have damaged the turbines in the turbopump."

Turbine inlet (and sometimes outlet) temperature is a standard measurement on any engine.  If someone had it on their screen, they would have seen it as it happened.  There's only one way for the temperature to get higher and that's to run closer to stoichiometric.  Depletion sensors are standard on any rocket too, but discretes are hard to eyeball in real-time to see what happens first unless it was an obvious time lag.  So for him to say it was a LOX-rich shutdown, that implies it was looked at it in reviews.
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Offline edkyle99

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #42 on: 09/11/2011 03:27 am »
btw. Doesn't imploded imply a violent crushing and shredding of the tank? The crushed tank was more along the lines of a slow crushing of the tank as the tank was drained.

Unless you've seen the video, how could you possibly know this?  How do you know, for example, that the tank didn't pop violently, leak, catch fire, and explode?

 - Ed Kyle

Offline douglas100

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #43 on: 09/11/2011 07:31 am »

 We've never seen photos or videos of the Falcon 1 that imploded on the launch pad and never flew.  We've never seen the Falcon 1 Flight 1 crash and explosion video - something that has to have involved more than just SpaceX  - for many years now - since it happened on a U.S. range.  Etc.   

I haven't heard of the Falcon 1 that imploded on the pad. When did that happen?

A video of the Falcon 1 F1 crash was posted on this forum but taken down soon afterward. I caught it by accident. The rocket went straight up out of camera shot, the sound of the engine died away, then about twenty seconds later it dropped tail first out of the sky followed by a large KABOOM. The camera shook a bit. It was quite spectacular.
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Offline iamlucky13

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #44 on: 09/11/2011 08:17 am »
btw. Doesn't imploded imply a violent crushing and shredding of the tank? The crushed tank was more along the lines of a slow crushing of the tank as the tank was drained.

Unless you've seen the video, how could you possibly know this?  How do you know, for example, that the tank didn't pop violently, leak, catch fire, and explode?

 - Ed Kyle

It's been a while, but from my memory, the impression I had at the time it was originally discussed was a crumpling, which would fit the issue described (valve failure during drain), but I suppose it's not conclusively known it didn't get more dramatic.

About the engine, as I understand it, this is an email that was circulated beyond the intended audience:
http://www.spacekb.com/Uwe/Forum.aspx/space-policy/2348/Test-Failure-of-SpaceX-Merlin-VTS1-221Engine

But yes, it is still a disappointment that SpaceX has chosen not to share the full development experience. Unsurprising, but disappointing.

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #45 on: 09/11/2011 09:05 am »
Quote
[email protected] - 12 Sep 2005 19:12
>
SpaceX attempted a full Mission Duty Cycle (MDC) test of the Merlin S/N
003 engine on Wednesday, 7 Sep 05 with catastrophic results.
>

So, since when is something that happened in 2005 "news" in 2011?
« Last Edit: 09/11/2011 09:07 am by docmordrid »
DM

Offline Tony Ostinato

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #46 on: 09/11/2011 09:06 am »
"I want historians to know the real story"

boy has that ship sailed, that ship sailed so long ago it was made of reeds.

i wonder if this can be packaged as a wowza news story. since the flight was a success they'll have to explain why its not, and theres no way to explain anything short enough for the viewer not to tune out. most people tune out at the words space or rocket anyways.

and theres always other stuff goin on.



Offline edkyle99

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #47 on: 09/11/2011 04:02 pm »
"I want historians to know the real story"

boy has that ship sailed, that ship sailed so long ago it was made of reeds.

You don't know the dogged historians that I know! 

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #48 on: 09/11/2011 04:45 pm »
I have no doubt SpaceX and NASA are working the issues and will continue to do so for many years, especially as crewed operations move forward. It is very much in SpaceXs interest to ensure a robust, safe, successful vehicle. And if I were a relatively new entrant into spaceflight, I would suck the living marrow of knowledge out of NASA's bones while I had the chance.

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Offline Nomadd

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #49 on: 09/11/2011 04:58 pm »
And if I were a relatively new entrant into spaceflight, I would suck the living marrow of knowledge out of NASA's bones while I had the chance.


 That's a unique way to put it and a little disturbing.
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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #50 on: 09/11/2011 06:01 pm »
And if I were a relatively new entrant into spaceflight, I would suck the living marrow of knowledge out of NASA's bones while I had the chance.


 That's a unique way to put it and a little disturbing.
Yes, perhaps too visual. Point being, by working closely with the incredible knowledge and experience of NASA personell and applying it to a commercial, vertically integrated, market competing company, the results, IMO, could be a truly spectacular future for Spaceflight. Which is supposed to be the point of this exercise...
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Offline cuddihy

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #51 on: 09/11/2011 10:34 pm »
There seem to be two storylines at SpaceX: one pie-in-the-sky storyline, intended for the rubes in the media, as well as the un-payed forums and congress, that pretends to be above board and honest, but that ignores or downplays serious difficulties and risks, that perpetually maintains an astericked launch date on the calendar to the left of the "Real" date, and that will sue to keep the storyline in place.

The other is the real story, openly shared with Nasa and commercial customers, of which hints periodically appear (such as this one, or the quote from the NASA station folks that suggests the "Real" launch date for COTS 2/3 is some time in Jan or Feb of next year, with potential station rendezvous '[move to phase 3'] no earlier than Feb ) -- I predict the launch date slip to 2012 will be announced around Halloween, and will be subtly blamed on 'an inability to receive approval to approach the station until next year', possibly with additional reference to the 'fortuitous' soyuz failure that makes this particular range chicken game unnoticed.
« Last Edit: 09/11/2011 10:35 pm by cuddihy »

Offline Lars_J

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #52 on: 09/11/2011 11:22 pm »
There seem to be two storylines at SpaceX: one pie-in-the-sky storyline, intended for the rubes in the media, as well as the un-payed forums and congress, that pretends to be above board and honest, but that ignores or downplays serious difficulties and risks, that perpetually maintains an astericked launch date on the calendar to the left of the "Real" date, and that will sue to keep the storyline in place.

Take out any reference to SpaceX, and your paragraph could describe NASA itself, and any aerospace corporation.

The public story is never the whole story. It's called public relations.

Offline Jason1701

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #53 on: 09/11/2011 11:43 pm »
The other is the real story, openly shared with Nasa and commercial customers, of which hints periodically appear

Must not be a really shocking story or they'd have had trouble getting customers.

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #54 on: 09/12/2011 02:47 am »
I haven't heard of the Falcon 1 that imploded on the pad. When did that happen?

It happened on December 19, 2005, during the first Falcon 1 launch campaign (which had seen a scrubbed first attempt on November 25, 2005).   The first stage was destroyed during fuel draining, after a scrub due to high winds, when the fuel pressurization system suffered a controller failure, causing the fuel tank to collapse.  The webcast was cut off, preventing any broadcast of the event.   

As a result, the first Falcon 1 flight used the second flight vehicle.  Even the second stage had to be replaced after the first second stage sprung a leak during a February 9, 2006 hot-fire test at Omelek.  The inaugural launch, which failed, did not occur until March 24, 2006.

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #55 on: 09/12/2011 02:07 pm »
From the article:

Quote
"There was no explanation or root cause analysis or corrective action for this particular anomaly," Daniel said Sept. 9 during the public meeting. "This is a relatively troublesome statement not to recognize that a premature engine shutdown was a significant event..."

As Ed points out, the article is short on answering the various "W's".  This particular quote is certainly out of its original context, and meaningless in this article, since the news is that SpaceX is in fact starting to talk about the root cause analysis.

It sounds very much to me like "engine out was given a surprise test".  Murphy simply doesn't care if it's SpaceX or SLS.  Poop happens.  Go ahead and call it a surprise shutdown rather than engine out if you will.

As to transparency, the phrase "just like the O-ring on STS-51C" gave me some pause.  From the Wiki article:

Quote
During the investigation into the disaster, it was reported to the Rogers Commission that during the launch of STS-51-C, the worst solid rocket booster (SRB) blow-by effects of any mission prior to STS-51-L occurred, indicating conclusively that the Viton O-rings were not sufficiently sealing the hot gases inside the combustion chambers of the SRBs while firing.

The public transparency on 51-C, unfortunately, came to light after 51-L, not before.  I make no judgements on the order of the transparency, but there it is.  At the same time, there's a big difference between the two anolmalies.

Jim's analysis sounds right to me: "It is just an additional feature that will be eliminated from future vehicles."  Which means it's not a bug?  Whew.

Quote
It was like a pack of rhinos in the dessert when they spot a fire...

Huh?  Rhinos in the ice cream?
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Offline Jim

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #56 on: 09/12/2011 02:23 pm »
The other is the real story, openly shared with Nasa and commercial customers, of which hints periodically appear

Must not be a really shocking story or they'd have had trouble getting customers.

Some of us only speak for NASA, can't say what they share with other customers.

Offline kevin-rf

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #57 on: 09/12/2011 02:48 pm »
It sounds very much to me like "engine out was given a surprise test".  Murphy simply doesn't care if it's SpaceX or SLS.  Poop happens.  Go ahead and call it a surprise shutdown rather than engine out if you will.

Where in the article does it state that the shutdown occurred before the planned shutdown time?

Maybe I have misread what has been published, but this is an event that happened during the planned shutdown of an engine or set of engines to one or more engines.

SpaceX has said nothing about any of the engines being shutdown before they planned to shut them down. That is not an engine out, engine out means an engine or set of engines quit early and the rest had to take up the slack. Maybe my reading skills are below par, but that is not what has been described as happening.

Based on what has been described and published, even if this Falcon 9 used a single Merlin 2 and this had happened the flight objectives would have been met. Apart from Saturn and Shuttle, can anyone come up with a real flight that was saved because of engine out?
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Offline douglas100

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #58 on: 09/12/2011 02:59 pm »
I haven't heard of the Falcon 1 that imploded on the pad. When did that happen?

It happened on December 19, 2005, during the first Falcon 1 launch campaign (which had seen a scrubbed first attempt on November 25, 2005).   The first stage was destroyed during fuel draining, after a scrub due to high winds, when the fuel pressurization system suffered a controller failure, causing the fuel tank to collapse.  The webcast was cut off, preventing any broadcast of the event.   

As a result, the first Falcon 1 flight used the second flight vehicle.  Even the second stage had to be replaced after the first second stage sprung a leak during a February 9, 2006 hot-fire test at Omelek.  The inaugural launch, which failed, did not occur until March 24, 2006.

 - Ed Kyle

Thanks for the information. I don't remember any mention of such a thing at the time. But maybe my memory's not what it used to be!
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Offline billh

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #59 on: 09/12/2011 03:55 pm »
I seem to remember seeing a picture of the buckled Falcon 1 tank. Implode sounds like too strong a word.

I would love to see the video of the first failed Falcon 1 flight, but SpaceX is merely being prudent not to release it. Those who want to portray them in a negative light (and they are legion) would run that video any chance they got. It's just good business sense not to release it.

Offline Downix

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #60 on: 09/12/2011 04:29 pm »
It sounds very much to me like "engine out was given a surprise test".  Murphy simply doesn't care if it's SpaceX or SLS.  Poop happens.  Go ahead and call it a surprise shutdown rather than engine out if you will.

Where in the article does it state that the shutdown occurred before the planned shutdown time?

Maybe I have misread what has been published, but this is an event that happened during the planned shutdown of an engine or set of engines to one or more engines.

SpaceX has said nothing about any of the engines being shutdown before they planned to shut them down. That is not an engine out, engine out means an engine or set of engines quit early and the rest had to take up the slack. Maybe my reading skills are below par, but that is not what has been described as happening.

Based on what has been described and published, even if this Falcon 9 used a single Merlin 2 and this had happened the flight objectives would have been met. Apart from Saturn and Shuttle, can anyone come up with a real flight that was saved because of engine out?

You ask a question then eliminate the two high profile examples, which says that you know about those flights. Those two alone are proof that engine out can save a mission. Are there others? None of manned launchers I am aware of.
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Offline Lars_J

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #61 on: 09/12/2011 05:07 pm »
But a question remains - Some claim that an unplanned/premature engine shutdown occurred. But this does not appear to be the case from what SpaceX says - Just that the engine ran hot at the end which *could* have resulted in an unplanned engine shutdown.

Unless I mistaken?
« Last Edit: 09/12/2011 05:11 pm by Lars_J »

Offline Comga

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #62 on: 09/12/2011 05:12 pm »
Back to context.  This is what those of us not in-the-know read in the article:

“I’d call it an oxidizer-rich shutdown,” former NASA astronaut Ken Bowersox, SpaceX’s vice president of astronaut safety and mission assurance, told Space News in a Sept. 9 interview. “So because of that, when you get that mixture change happening, the temperatures can go up higher than you want inside the gas generator. Bowersox added that “those temperatures could have damaged the turbines in the turbopump.”

That sounds like a planned shutdown where the mix went off-nominal.  There is eveidence to support that both the early two engine and later seven engine shut-downs went as planned from a thrust standpoint.  What is pointed to here is the POTENTIAL to damage a turbopump in an engine that has been shut down and is not yet planed to be recovered.   There is nothing presented saying it can CAUSE a shut-down, as Lars_J suggests, just an issue with a planned shut-down.

This is not the first anomaly in shutting down a Merlin-1.  Falcon 1 Flight 3 was lost in another anomaly, where the engine provided unpredicted thrust after staging.  SpaceX dealt with that expeiditiously, as evidenced by Falcon 1 flights 4 & 5 and Falcon 9 flights 1 & 2.  There is no reason to believe that they can't deal with this, or that it threatens missions.

All anomalies need to be worked.   This one seems to be less than mortifying.
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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #63 on: 09/12/2011 05:13 pm »
If the fuel flow terminated only slightly early, a fraction of a second or so, wouldn't that immediately lead to a temperature-rise in the gas generator, which in turn would lead to the engine controller shutting down the oxygen flow immediately?

Comga, isn't that what you're saying too?
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Offline Comga

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #64 on: 09/12/2011 05:21 pm »
Comga, isn't that what you're saying too?

On second thought, no.

My take is that the taper of oxidizer flow was less than that for fuel flow.  An early fuel cut-off should have been visible in the acceleration profile.

I wish Jim was allowed to help out here, but don't expect it.

edited to reverse my response
« Last Edit: 09/12/2011 05:22 pm by Comga »
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Offline ugordan

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #65 on: 09/12/2011 05:39 pm »
The SN story was updated. You can put some of the unknowns to rest now.

Takeaways:

Quote
An oxygen-rich shutdown is “not a catastrophic event for the Merlin engine,” Bowersox said. “We’ve been through this on the test stand and we know what it looks like for our engines, so we know that this was not a risk to the mission.”

Quote
SpaceX disputes Daniel’s characterization of the engine anomaly as a premature shutdown.

“We did not have a premature engine shutdown,” Bowersox told Space News.

Bowersox also said SpaceX informed NASA of the engine anomaly right away.

“This information was presented to NASA and to the [Federal Aviation Administration] not too long after the mission,” Bowersox said. “But it didn’t go to the Aerospace Safety Advisory Panel, it went to some of the different NASA programs that we work with.”

SpaceX spokesman Robert Block said that NASA received a briefing about the flight Dec. 15. SpaceX subsequently delivered full-rate telemetry for the flight on Dec. 28. A full flight report to the agency followed on Feb. 24, Block said.
« Last Edit: 09/12/2011 05:40 pm by ugordan »

Offline R.Simko

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #66 on: 09/12/2011 05:49 pm »
I haven't heard of the Falcon 1 that imploded on the pad. When did that happen?

It happened on December 19, 2005, during the first Falcon 1 launch campaign (which had seen a scrubbed first attempt on November 25, 2005).   The first stage was destroyed during fuel draining, after a scrub due to high winds, when the fuel pressurization system suffered a controller failure, causing the fuel tank to collapse.  The webcast was cut off, preventing any broadcast of the event.   

As a result, the first Falcon 1 flight used the second flight vehicle.  Even the second stage had to be replaced after the first second stage sprung a leak during a February 9, 2006 hot-fire test at Omelek.  The inaugural launch, which failed, did not occur until March 24, 2006.

 - Ed Kyle

Ed, thanks for the information on the fuel tank collapse.  I don't remember hearing about that before. 

To me, this shows how far SpaceX has come.   We have all seen the problems SpaceX has had with their early launch attemps'.  Not that  they have been alone in the space launch field in having early difficulties with new launchers.

What this says to me is how far SpaceX has come in learning from their mistakes and I would think increasing their quality control.  After 3 straight launch failures of their F1 rocket, they then launched it successfully twice in row and then moved on to their next launch vehicle, the F9 which they have successfully launched twice in a row.  You can also throw in the successful recovery of their Dragon spacecraft.

Of course I know that you and others on this site are aware of this. I'm just pointing it out here on this "anomaly" page, so that we can look at it from a glass half full perspective.

Chris Bergin also wrote an excellant article where he detailed early SpaceX launch difficulties and how far they have come since then.

Sincerely Bob

Edit-spelling correction
« Last Edit: 09/12/2011 06:02 pm by R.Simko »

Offline ugordan

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #67 on: 09/12/2011 06:31 pm »
Kirstin Grantham (SpaceX PAO) said this in one blog's comment section:

Quote
What Bowersox said, but did not make it into the current version of the article, was that there was no premature shutdown of the engine.

The engines did not fail. The Merlin engine has a robust design that can easily withstand this type of event.

There was no impact on mission success. The last mission successfully achieved all mission objectives.

This would be a problem for the long term goal of reusability as engines would need to be repaired before they could be used again.

However, the issue was easily resolved. 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.

SpaceX discussed the issue with NASA and resolved it to their satisfaction months ago. SpaceX completed a full post-flight report on all indications from Falcon 9 flight 2. That report was distributed to NASA officials. NASA personnel were briefed and the situation was explained to NASA’s satisfaction.

Kirstin Grantham, SpaceX Spokeswoman


Off topic, but I wonder why SpaceX people avoid this forum like the plague.

Offline edkyle99

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #68 on: 09/12/2011 06:33 pm »
My take is that the taper of oxidizer flow was less than that for fuel flow.  An early fuel cut-off should have been visible in the acceleration profile.

Here's my guess.  The first stage runs seven engines to propellant depletion.  Something, a sensor somewhere, has to detect the depletion of fuel or oxidizer (they never run out perfectly in sync) to trigger engine shutdown.  My guess is that sensor, in this case an RP level or flow sensor, did not trigger the shutdown in a timely manner.  The engines, all seven of them, would have shut down essentially when expected, starved of fuel, but not in the graceful, ideal manner.  (An alternate possibility is that the issue only affected some of the engines, since some of the feedlines are longer than others.)

As Jim noted earlier, the first Delta 4 Heavy suffered a false sensor reading in a somewhat similar fashion, except in that instance it signaled that propellant was exhaust a few seconds earlier than it actually was due to something like cavitation in a propellant line.

 - Ed Kyle
« Last Edit: 09/12/2011 06:41 pm by edkyle99 »

Online docmordrid

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #69 on: 09/12/2011 06:41 pm »
Off topic, but I wonder why SpaceX people avoid this forum like the plague.

Because there are people that would debate them & come up with conspiracy theories if they said the sky was blue?

Not that they'd just do it to them, but still....
« Last Edit: 09/12/2011 06:43 pm by docmordrid »
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Offline krytek

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #70 on: 09/12/2011 06:45 pm »
Thank you hobby space.
“We did not have a premature engine shutdown,” Bowersox told Space News.
http://spacenews.com/civil/spacex-acknowledges-falcon-engine-anomaly-during-latest-launch.html

So basically all that happened was a lean mix ratio at shutdown. A lot of noise over nothing.

Offline kevin-rf

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #71 on: 09/12/2011 07:02 pm »

What Kirstin Grantham, SpaceX Spokeswoman posted on http://www.americaspace.org/?p=9044#comments :
Quote
However, the issue was easily resolved. 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.

Anyone make a WAG if it was only the center engine? It would have the shortest length of pipe.

So it was not an early shutdown, engine out was not tested, just the planned shutdown did not happen in the manor SpaceX has grown accustom. I think a good lawyer could get that engine a nice settlement from dear Ol' Elon ;)
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Offline Antares

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #72 on: 09/12/2011 07:15 pm »
wouldn't that immediately lead to a temperature-rise in the gas generator, which in turn would lead to the engine controller shutting down the oxygen flow immediately?

Only if the temperature is fed into an engine control or abort algorithm.  That's kind of a complicated design.


My take is that the taper of oxidizer flow was less than that for fuel flow.  An early fuel cut-off should have been visible in the acceleration profile.

Depletion algorithms are complicated and different in flight than in ground test.  Since it's only the second flight, this is why it was my kneejerk for the fault.  After thinking about it more, there could have been a slow (or fast) valve or a level sensing error.  While those are single-fault from an Occam's razor standpoint, depletion is an even simpler possibility because there are so many variables that have to be estimated correctly.  Liquid level is falling at a certain speed, which may be complicated since flow is volumetric and not linear.  The pumps are spinning down.  Maybe the ECOs aren't in the analytically perfect place because of other constraints.  There's lag time in the control system.  The dynamics are different than ground test since the vehicle is accelerating.  Etc.
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Offline Comga

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #73 on: 09/12/2011 08:49 pm »
My take is that the taper of oxidizer flow was less than that for fuel flow.  An early fuel cut-off should have been visible in the acceleration profile.

Depletion algorithms are complicated and different in flight than in ground test.  Since it's only the second flight, this is why it was my kneejerk for the fault.  After thinking about it more, there could have been a slow (or fast) valve or a level sensing error.  While those are single-fault from an Occam's razor standpoint, depletion is an even simpler possibility because there are so many variables that have to be estimated correctly.  Liquid level is falling at a certain speed, which may be complicated since flow is volumetric and not linear.  The pumps are spinning down.  Maybe the ECOs aren't in the analytically perfect place because of other constraints.  There's lag time in the control system.  The dynamics are different than ground test since the vehicle is accelerating.  Etc.

Thanks.  Obviously you are a professional at this and I am not.

Given that SpaceX uses pressurized fuel for the TVC, they can't risk depleting the RP-1.  Also, Bowersox says that it was "an oxygen-rich shut-down" so they didn't deplete the LOX.  That says it's more likley a slow shut-off, where the LOX valve was slower than the RP-1 valve, or farther upstream, or something else that allowed it to run a bit longer.   It isn't clear (at least to one not educated in the field) what "Depletion algorigthms" are involved in a shut-down where neither fuel nor oxidizer is depleted.
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Offline JWag

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #74 on: 09/12/2011 08:53 pm »
Is there a general method for a controlled engine shutdown? 

For example, in my (mostly ignorant) mind, I imagine first shutting the valves to the gas generator, oxidizer first.  Then waiting a short time until the GG exhaust temp drops and turbine speed begins to fall.  Then shutting off the main oxidizer valve, followed by the main fuel valve.  I bet it would be beneficial to drag out the wait time a little, as the action of pumping would rapidly decelerate the turbopumps.

I can only begin to imagine the consequences of this.  Is there a "water hammer" effect in multi-engine systems when you shut off propellant flow to one engine?  Or is this dampened by the pogo accumulator(s)?  I presume it depends on how much of the feedlines are shared between engines.

I imagine it all depends on the propellants used and engine type.


In any case, this seems to pale in comparison to all the things that went wonky on Apollo 6's Saturn V.

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #75 on: 09/12/2011 09:22 pm »
 I never did quite understand what they did after the third F1 failure, but I thought it had something to do with depleting or cutting off the O2 so the fuel from the regen cooling system on the M1c wouldn't cause the staging burp that caused so many words mothers wouldn't have approved of at the stage recontact at the end of the launch video.
« Last Edit: 09/12/2011 09:23 pm by Nomadd »
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Offline go4mars

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #76 on: 09/12/2011 09:27 pm »
I never did quite understand what they did after the third F1 failure, but I thought it had something to do with depleting or cutting off the O2 so the fuel from the regen cooling system on the M1c wouldn't cause the staging burp that caused so many words mothers wouldn't have approved of at the stage recontact at the end of the launch video.

They just increased the time before separation by a few extra seconds while it "blew down".  The 3rd failure still had 10 psi in the chamber at separation IIRC (which they didn't notice before the flight at sea level testing in 14 psi).
« Last Edit: 09/12/2011 09:30 pm by go4mars »
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Offline Nomadd

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #77 on: 09/12/2011 11:53 pm »
I never did quite understand what they did after the third F1 failure, but I thought it had something to do with depleting or cutting off the O2 so the fuel from the regen cooling system on the M1c wouldn't cause the staging burp that caused so many words mothers wouldn't have approved of at the stage recontact at the end of the launch video.

They just increased the time before separation by a few extra seconds while it "blew down".  The 3rd failure still had 10 psi in the chamber at separation IIRC (which they didn't notice before the flight at sea level testing in 14 psi).

 I know that was the immediate fix that got them going again so fast, but my admittedly imperfect brain has some vague memory of an intention to come up with a better solution so they could keep that gravity lossy staging  interval down to a minimum.
 I was just polluting this thread with my meanderings trying to understand the end of stage fuel use profile. But it doesn't really serve a point with the vague information that's come to light so far.
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Offline cuddihy

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #78 on: 09/13/2011 02:54 am »
There seem to be two storylines at SpaceX: one pie-in-the-sky storyline, intended for the rubes in the media, as well as the un-payed forums and congress, that pretends to be above board and honest, but that ignores or downplays serious difficulties and risks, that perpetually maintains an astericked launch date on the calendar to the left of the "Real" date, and that will sue to keep the storyline in place.

Take out any reference to SpaceX, and your paragraph could describe NASA itself, and any aerospace corporation.

The public story is never the whole story. It's called public relations.

Yeah, right up until you sue...

Offline ArbitraryConstant

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #79 on: 09/13/2011 04:52 am »
There seem to be two storylines at SpaceX: one pie-in-the-sky storyline, intended for the rubes in the media, as well as the un-payed forums and congress, that pretends to be above board and honest, but that ignores or downplays serious difficulties and risks, that perpetually maintains an astericked launch date on the calendar to the left of the "Real" date, and that will sue to keep the storyline in place.

Take out any reference to SpaceX, and your paragraph could describe NASA itself, and any aerospace corporation.

The public story is never the whole story. It's called public relations.

Yeah, right up until you sue...
In this case it sounds like what happened did not, and even if it happened again in the future would not, prevent successful insertion into the desired orbit.

Oxygen rich shutdown overheated the engines before reentry had a chance to. That's a shame if you're trying to reuse the stage, but a non-issue on an expendable stage, which is all anyone is relying on Falcon 9 for at this point.
« Last Edit: 09/13/2011 04:55 am by ArbitraryConstant »

Offline MP99

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #80 on: 09/13/2011 08:48 pm »
Given that SpaceX uses pressurized fuel for the TVC, they can't risk depleting the RP-1.

Isn't there a converse implication that an unexpected termination of RP-1 flow could interrupt TVC operation?

However, if this happens as the engine is shutting down, presumably impact would be limited?

cheers, Martin

Offline mgreb

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #81 on: 09/13/2011 10:08 pm »
Maybe we are reading too much into this,  It could be as simple as a couple of sluggish o2 valves.   I would think that this issue probably has been taken care of as the last flight was quite a few months ago.

Offline kevin-rf

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #82 on: 09/14/2011 01:12 am »
Honestly, this has gotten more coverage than the launch fireball. Which was a more serious issue?
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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #83 on: 09/14/2011 06:57 am »
Honestly, this has gotten more coverage than the launch fireball. Which was a more serious issue?
Not the launch fireball. That did not threaten the launcher in any way, despite the impressive looking fire works.

Offline ugordan

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #84 on: 09/14/2011 07:25 am »
Honestly, this has gotten more coverage than the launch fireball. Which was a more serious issue?

Not the launch fireball. That did not threaten the launcher in any way, despite the impressive looking fire works.

The upshot is this didn't threaten it, either. It occured when the 1st stage was already done doing its thing. Even if something happened to blow during shutdown down below, very likely still wouldn't have mattered for staging and 2nd stage.

In terms of mission impact risk, I put this at lower than the 2nd stage roll on F9-01 and about right or lower than nozzle cracking on F9-02.

In fact, the more I think about this issue, the more I'm puzzled as to why it was actually made into a news article 9 months after the event. The headline could very well have been "Second Falcon 9 experienced in-flight anomalies". Who ever thought there would be no anomalies on only the second flight? Much worse things could have happened on #02 and still can happen on #03. Does that really prove anything?

Offline mmeijeri

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #85 on: 09/14/2011 07:30 am »
Only if the temperature is fed into an engine control or abort algorithm.  That's kind of a complicated design.

Can you elaborate why this would be complicated? Maybe because you don't need it on unmanned launches? And wouldn't this be one parameter that would be monitored by an emergency detection system for manned launches?
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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #86 on: 09/14/2011 07:31 am »
Typical slow media season stuff. Any day now I'm expecting a banner headline that the sun has changed its position in the sky between dawn & noon  :P
« Last Edit: 09/14/2011 07:32 am by docmordrid »
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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #87 on: 09/14/2011 07:35 am »
No! Really?!?  ;D

Offline ugordan

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #88 on: 09/14/2011 08:42 am »
One previously unknown bit for us outsiders in this article: http://www.floridatoday.com/article/20110914/NEWS02/109140314/1007/rss06/SpaceX-engine-anomaly-troubles-panelist

Quote
SpaceX says the rocket's nine first-stage Merlin engines shut down on time, but four experienced a momentary spike in temperature when fuel cut off slightly before the oxidizer, prompting an
"oxidizer-rich" shutdown that could have damaged turbines.

So 4 out of 7 engines were affected.

Quote
"We've seen it, we've seen the corrective actions and it's a rather simple fix, what they're planning to do," said Alan Lindenmoyer

Other than that it's mostly about Daniel taking issue with SpaceX' statements how it's not a serious issue, comparing it to the recent Soyuz failure and NASA's post-Challenger safety culture.

Offline mlorrey

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #89 on: 09/14/2011 11:39 am »
The point is, that it was a matter of shutdown sequencing, and happens AFTER stage separation, so it never posed a risk to the mission or the payload, only to the potential reusability of the engines.
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Offline ugordan

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #90 on: 09/14/2011 11:40 am »
Uh... shutdown happens BEFORE stage separation unless you want a repeat of F1-03.

Offline JohnFornaro

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #91 on: 09/14/2011 12:47 pm »
It sounds very much to me like "engine out was given a surprise test"...

Where in the article does it state that the shutdown occurred before the planned shutdown time?

Actually, it seems that your question should be: "Where in the article does it state that the anomaly was anything but a surprise?"

If it turns out that the surprise anomaly triggered an orderly shutdown of the system, then for me, this is the third cool thing that SpaceX has done, in the field of valor where Murphy is the main opponent.  First, their shutdown on the launch pad, followed by a restart a short time later.  Second, trimming a nozzle in the field.  Third, this.  The salient term was the term "surprise test".  Kinda like a pop quiz.

But I do get the critique that "engine out" was a term used prematurely, and before all data were accounted for.

As to that failed launch where the video was cut off.  I'm sure the cameras kept rolling, for the sake of forensic examination.  It's not surprising to think that a still from the video will not grace the cover of their annual statement.  [Warren Buffet, flippin' thru the glossy: "You want me to invest in this company?]  Of course we can hope that some years from now, the video will be released to the public, for historic reasons, and to satisfy those of us who prefer, when given this choice, real rocket explosions, not Hollywood imitations.  I mean, that's my practical perspective.

Off topic, but I wonder why SpaceX people avoid this forum like the plague.

For the same reason that Mr. Bolden and other NASA officials don't post here under their own names?

And to Antares:  Wouldn't a depletion algorithm have coded into it and expected rate of depletion?  There has got to be a time value to that rate.
Sometimes I just flat out don't get it.

Offline Antares

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #92 on: 09/14/2011 03:42 pm »
Sure, but like I said, you don't know exactly how it's going to behave in flight while accelerating.

Martin: abort logic is complicated in general.  Have to screen for false positives, which probably means 2 or 3 sensors.  Have to select what the limits really should be while allowing natural variations (and this with a system with relatively little experience - not as much of a problem for commercial crew when more flights are under the belt).  Have to pick some sort of persistency check while still being able to respond fast enough.

And then there's coding all of that.
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Offline JohnFornaro

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #93 on: 09/14/2011 06:48 pm »
Quote from: Antares
Sure, [a depletion algorithm would have a rate of depletion coded into it] but like I said, you don't know exactly how it's going to behave in flight while accelerating.

So my next question would be:  Since it would be well known that a stationary test article would not deplete fuel & oxidizer the same way that an accelerated test article would, are they able, or do they interpret, those stationary tests with that acceleration in mind?  Or do they test or model fuel depletion on an accelerating sled, say?
Sometimes I just flat out don't get it.

Offline hyper_snyper

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #94 on: 09/14/2011 07:12 pm »
That's interesting I didn't not know variables like rate of depletion are hard coded into the flight software of launch vehicles.  Is there any implementation where that rate can be measured dynamically on the fly?

Offline mr. mark

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #95 on: 09/14/2011 07:36 pm »
SpaceX says the rocket's nine first-stage Merlin engines shut down on time, but FOUR experienced a momentary spike in temperature when fuel cut off slightly before the oxidizer, prompting an "oxidizer-rich" shutdown that could have damaged turbines.

http://hobbyspace.com/nucleus/?itemid=32436&utm_source=twitterfeed&utm_medium=twitter

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #96 on: 09/14/2011 07:40 pm »
SpaceX says the rocket's nine first-stage Merlin engines shut down on time, but FOUR experienced a momentary spike in temperature when fuel cut off slightly before the oxidizer, prompting an "oxidizer-rich" shutdown that could have damaged turbines.

http://hobbyspace.com/nucleus/?itemid=32436&utm_source=twitterfeed&utm_medium=twitter

http://forum.nasaspaceflight.com/index.php?topic=26739.msg806223#msg806223

Offline Antares

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #97 on: 09/14/2011 08:35 pm »
My "sure" was in relation to the phrase "time value" not to anything else.  ECOs go dry, the prop guys have SWAG'd a time to wait if any, and then MECO is issued.
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Offline JohnFornaro

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #98 on: 09/15/2011 12:28 pm »
Quote from: Antares
My "sure" was in relation to the phrase "time value" not to anything else.

Now I'm confused.  A depletion algorithm would have a "time value".  But it would not be a "rate of depletion"?  With the term "rate" including a time value.  What would the pseudo-code of that algortithm be?  Is the time value simply a clock pulse, and not actually a "rate"?

And regarding the stationary versus accelerating test article; would there not be some coded algorithm regarding acceleration, and some model where the the rate of depletion could be compared between the two?
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #99 on: 09/16/2011 04:13 pm »
Well, the first hit for me on the googol revealed:

http://www.patentgenius.com/patent/6695256.html

Quote
In order to preserve the booster stage rocket engine for re-use, the engine must be properly shut down at or near the end of the launch boost stage. That is, the engine must be shut down prior to violating any engine requirements that may resultin some sort of permanent engine or vehicle damage. For, example...

...SUMMARY OF THE INVENTION

In view of the foregoing, a primary object of the present invention is to provide a system for monitoring a cryogenic propellant, irrespective of that propellant being a pure liquid. Another objective of the present invention is to provide acryogenic depletion monitoring system that is easily adaptable for operation with current launch vehicles.

...

According to a first aspect of the present invention, a cryogenic propellant depletion monitoring system is provided that includes a processing system containing logic to determine and monitor at least a first propellant parameter associated withthe cryogenic propellant in the launch vehicle's cryogenic feed line. Additionally, the system contains control means to initiate engine shut off once at least one of the determined propellant parameters falls below a minimum allowable threshold. Thesystem is operable to determine these propellant parameters and initiate booster engine shutdown irrespective of the cryogenic propellant being a pure liquid.

Pretty interesting reading and a bit of insight on a depletion algorithm.
Sometimes I just flat out don't get it.

Offline Chris Bergin

Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #100 on: 09/17/2011 07:17 pm »
I've trimmed the thread, as it contained a strange reference to C2/C3, which is not related to this thread (as much as one or two may want to believe it is).

Discuss facts, not wild unsupported assumptions.

Offline GRSG

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Re: SpaceX Acknowledges Falcon 9 Engine Anomaly
« Reply #101 on: 09/24/2011 01:50 am »
The "anomaly" had no bearing whatsoever on the success of the mission.
Do you want SpaceX to tell you about every small bug that hit the windshield on the way up? That's how relevant was this "anomaly"

It did not cause any problems to the 100% success of the mission, it didn't cause any consternation to the flight controllers, it was not an O ring type of failure that could escalate into something more serious.

Space flight admittedly is unforgiving, but if you want conspiracies, go investigate Buzz Aldrin's new girlfriend, much juicier story there.

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