SpaceX Falcon 9/Dragon CRS SpX-1 MISSION GENERAL DISCUSSION

[upjin]

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

Actually there is, Atlas III flew 6 additional RD-180s.

Still not statistically significant.

look at their families.

That would give an unrealistic low reliability to the rd180, given several zenit failures from the rd171 (I expect western procedures to have improved on the reliability of the rd171). If we followed your suggestion, though, the merlin1c and rd180 are still pretty reasonably equivalent, to the limits of statistical uncertainty.

My point is that until another failure occurs for Merlin 1c, it is very difficult to get a statistically significant contrast between the two engines.

rd-171/180 staged combustion engine are more complex, each of those generate lot more thrust than  single 1c, also at much higher isp. zenit 2/3 launched 51 times and only 2~3 failures directly caused by rd-171.

 on the other hand spacex's flight electronic seems doing much better job  taking care their engines than zenit or russian rockets. 1c generate lot less thrust, and gas generator cycle is more simple design.

Comparing rd-171/180 and merlin is like comparing apple and orange. Personal opinion, merlin is still very immature. 1c was rushed out in order to grab NASA's contracts.  i say, gas generator cycle 600kN class RP-1/LOX engine supposed to be lot more reliable than that.

In addition, there are negative arguments about American companies that are using Russian rockets, which can be considered an embarrassment to America and is hurting the domestic industry.  Because many would argue that SpaceX rockets are made in America, which is providing a needed domestic capability.

So in that light, which reflects political and domestic technology issues, the U.S. made SpaceX Merlins would be preferable to Russian rockets.  Irregardless of any slight statistical advantages in reliability.

[Jim]

*If* this was a RUD event for engine 1 - Would this be the first time a LV has survived an "engine RUD" and still delivered the payload successfully?

I'm wondering about that too.  Did we witness an historic first tonight?

No, SA-6 did it first.

http://history.nasa.gov/SP-4206/ch11.htm#329

[Jason1701]

*If* this was a RUD event for engine 1 - Would this be the first time a LV has survived an "engine RUD" and still delivered the payload successfully?

I'm wondering about that too.  Did we witness an historic first tonight?

No, SA-6 did it first.

http://history.nasa.gov/SP-4206/ch11.htm#329

Did SA-6 have an RUD? That page implies the engine was shut off without anything breaking.

[Jim]

*If* this was a RUD event for engine 1 - Would this be the first time a LV has survived an "engine RUD" and still delivered the payload successfully?

I'm wondering about that too.  Did we witness an historic first tonight?

No, SA-6 did it first.

http://history.nasa.gov/SP-4206/ch11.htm#329

Did SA-6 have an RUD? That page implies the engine was shut off without anything breaking.

According to Spacex, they didn't have a RUD.

[jabe]

any stuffed dragons sen at mission control this time?
jb

[yg1968]

SpaceX:

Update on SpaceX CRS-1 Mission: October 10

The SpaceX CRS-1 mission reached a critical milestone today, October 10, with the Dragon spacecraft successfully attaching to the space station.

The mission, the first of at least 12 to the International Space Station under the company’s cargo resupply contract with NASA, began with a Sunday, October 7 launch from Cape Canaveral, FL. As a result of shutting down one of its nine engines early shortly after the launch, the Falcon 9 rocket used slightly more fuel and oxygen to reach the target orbit for Dragon. For the protection of the space station mission, NASA had required that a restart of the upper stage only occur if there was a very high probability (over 99%) of fully completing the second burn. While there was sufficient fuel on board to do so, the liquid oxygen on board was only enough to achieve a roughly 95% likelihood of completing the second burn, so Falcon 9 did not attempt a restart. Although the secondary payload, the Orbcomm satellite, was still deployed to orbit by Falcon 9, it was done so at the lower altitude used by Dragon in order to optimize the safety of the space station mission.

SpaceX and NASA are working closely together to review all flight data so that we can understand what happened with the engine, and we will apply those lessons to future flights. We have achieved our goal of repeatedly getting into orbit by creating a careful, methodical and pragmatic approach to the design, testing and launch of our space vehicles. We will approach our analysis in the same manner, with a careful examination of what went wrong and how to best address it.  Additional information will be provided as it is available.

###

This press release from SpaceX debunks a lot of the speculation and "educated" guesses on this thread.

[Jason1701]

*If* this was a RUD event for engine 1 - Would this be the first time a LV has survived an "engine RUD" and still delivered the payload successfully?

I'm wondering about that too.  Did we witness an historic first tonight?

No, SA-6 did it first.

http://history.nasa.gov/SP-4206/ch11.htm#329

Did SA-6 have an RUD? That page implies the engine was shut off without anything breaking.

According to Spacex, they didn't have a RUD.

That doesn't matter, we know they did. I'm asking you, did SA-6? Or any other launch vehicle that continued up to orbit?

[Lars_J]

According to Spacex, they didn't have a RUD.

That doesn't matter, we know they did. I'm asking you, did SA-6? Or any other launch vehicle that continued up to orbit?

I agree that a RUD looked likely based on the low-quality footage, but if SpaceX denies it - and they have the more data - what proof can you offer? How do you "know" it?

[Avron]

Back to the question I wanted to ask anyone that may have any idea why SpaceX has not used this flight to advertise on the dragon.. look at  all the pics.. inside and out.. no Spacex..  look at the last fight.. again.. nice white sides and no sign .. I mean U cannot miss the CANADA on the arm..   Did Spacex marketing goof?

[e of pi]

Back to the question I wanted to ask anyone that may have any idea why SpaceX has not used this flight to advertise on the dragon.. look at  all the pics.. inside and out.. no Spacex..  look at the last fight.. again.. nice white sides and no sign .. I mean U cannot miss the CANADA on the arm..   Did Spacex marketing goof?

There was a big "SpaceX" logo on the side of the booster, and on the nosecone (ejected during ascent). There were also Dragon logos on the solar panel fairings (ejected as part of panel deployment) and there's one on the outside of the GNC bay door (open during approach and grapple, and the logo is on the side of the door that's against the capsule). That's about three or four company-specific logos, all apparently carefully selected to not be visible during approach and grapple. A bit more than coincidence, I suspect, but I'm not sure if it's NASA-required or something SpaceX decided to do themselves.

[Prober]

"The mission, the first of at least 12 to the International Space Station under the company’s cargo resupply contract with NASA, began with a Sunday, October 7 launch from Cape Canaveral, FL. As a result of shutting down one of its nine engines early shortly after the launch, the Falcon 9 rocket used slightly more fuel and oxygen to reach the target orbit for Dragon. For the protection of the space station mission, NASA had required that a restart of the upper stage only occur if there was a very high probability (over 99%) of fully completing the second burn. While there was sufficient fuel on board to do so, the liquid oxygen on board was only enough to achieve a roughly 95% likelihood of completing the second burn, so Falcon 9 did not attempt a restart."

can someone explain the number for me?

1) If the "claim" F9 is built for an engine out, then the 2nd stage would have enough "margin".

2) Believe the number was 30secs of extra burn time of the 2nd stage.  So if correct enough margin should have been available for the 2nd burn no?

3) Only issue I can see is the pre-chill time before ignite where loss of Lox might take place.

Can someone clarify?

[kevin-rf]

Prober, Propellants lost and increased gravity losses resulted in a first stage underperformance that the upper stage had to also make up for, so it did not have enough margin for the second burn.

[Comga]

According to Spacex, they didn't have a RUD.

That doesn't matter, we know they did. I'm asking you, did SA-6? Or any other launch vehicle that continued up to orbit?

I agree that a RUD looked likely based on the low-quality footage, but if SpaceX denies it - and they have the more data - what proof can you offer? How do you "know" it?

Can we chill on this?
SpaceX claims that their engine continued intact.  It did not "Disassemble".  We saw things flying off.  SpaceX claims they were designed to blow out in case of engine malfunction.  Parts of the booster fairings did "disassemble".  SpaceX never used the term RUD.  There is no reason to doubt their honesty.   There is also no expectation for them to make dramatic statements.

Someone with better knowledge of the Apollo program can probably say how much if any hardware was shed in the SA-6 engine failure.  Arguing over what fraction of the engine mass or part count must be shed before one chalks up a 1 in the RUD column is sillier than the argument over whether this flight counts as a success or failure.

[cordor]

 on the other hand spacex's flight electronic seems doing much better job  taking care their engines than zenit or russian rockets.

It has nothing to do with electronics but an effect of the fuel-oxidizer ratio

In space launch history, there were many accidents cause by bad sensors, wirings, computers. So far, that hasn't happen to falcon rocket yet(if i remember correctly). F9 Flight 3 had valve problem, sensors detected that and terminated launch sequence. If not, theye could be another midair explosion just like many other rocket accidents.

[beancounter]

On the Missions thread, Jim indicated belief that the poster sent up in the Dragon was 'unprofessional'.  Guess it could be viewed in that light however SpaceX has a bit of a rep' for being shall we say, unconventional so I'd say it's probably not terribly unexpected and 'unprofessional' is a bit OTT.  They've demonstrated total professionalism in the technical and management aspects of the program.  A little leeway is not really asking too much, surely.

[Antares]

Wow, lots of posts while the rest of us were working, exercising and having dinner. Here's what I have to say.

If Falcon can make mission with 8 engines immediately after it leaves the pad, then it's leaving performance on the table when all 9 are running. Engine-out success is not black and white: it depends on when and how heavy the payload is. Please get this into your head. Let's start a Q&A-section discussion on it if you don't understand.

FSFN. if you've ever met Justin and understood how he's treated well-respected space journalists, you'll know why Chris, his other writers, and NSF is the place to be.

I don't agree with Jim on flight computers.

[Kabloona]

Re professionalism...they launched on the first attempt, proved their advertised engine-out capability (albeit in ugly fashion) and berthed with ISS ahead of schedule.

 Guess Jim's got to find *something* to gripe about. 

[rubicondsrv]

Re professionalism...they launched on the first attempt, proved their advertised engine-out capability (albeit in ugly fashion) and berthed with ISS ahead of schedule.

 Guess Jim's got to find *something* to gripe about. 

I think the engine failure is a good thing to gripe about,it shouldn't have happened, and needs to be fixed.

The poster is not a big deal unless it violates terms of their contract.

[cordor]

stacking up these micro engines, we got lots and lots of engine out capability. 

[edkyle99]

Believe the number was 30secs of extra burn time of the 2nd stage.  So if correct enough margin should have been available for the 2nd burn no?

I came up with 28 seconds extra for the first stage and 16 seconds extra for the second stage.  The second burn for a nominal Orbcomm insertion would have been a short one, since it would only have needed to provide 155-165 m/s or so delta-v.  SpaceX probably had to trade 2nd burn margin for Dragon margin in its mission design, to the benefit of Dragon, which meant that the extra 16 seconds just cut too close to meet NASA's ISS safety requirement.   

By the way, I'm thinking that this engine-out was historic.  SA-6 was, as best I can recall, the last time a first stage engine out occurred on a U.S. launcher and orbit was achieved.  (Apollo 13 and the Shuttle abort to orbit were not "first stage" shutdowns).  The SA-6 shutdown occurred at the T+116 second mark, causing the remaining engines to burn only about two seconds longer to compensate, with the S-IV stage also burning longer to reach a LEO that was lower, and therefore easier, to reach than the Dragon CRS-1 orbit. 

Falcon 9 No. 4, then, with its shutdown at T+79 sec, seems to have set the all time record for earliest engine shutdown while still making orbit.  This was a serious test, and Falcon 9 passed.

 - Ed Kyle