SpaceX COTS Demo 1 Updates

[joshcryer]

Josh - how is the analysis going so far? Is there a particular area you think could be the cause of a NET Thursday versus Wednesday?

I have no particular justification for my belief, but I think Wednesday would be a best case scenario and I'd be genuinely surprised if it happens. NET Wednesday is official I guess, but that doesn't mean it'll launch Wednesday.

[Robotbeat]

Press kit:

The result is the most advanced heat shield ever to fly, it can potentially be used hundreds of times for Earth orbit reentry with only minor degradation each time (like an extreme version of a Formula 1 car's carbon brakepads) and can even withstand the much higher heat of a moon or Mars velocity reentry.

"potentially be used hundreds of times for Earth orbit reentry" - I had not realised that!

cheers, Martin

Yes, quite interesting!

[rdale]

I have no particular justification for my belief

Thanks for clarifying, I thought you had some insight.

[joshcryer]

rdale, sorry about that, I should add in my sig that I am not an insider, just following SpaceX really closely. Shouldn't state gut feelings as if they're fact. Apologies.

[Lars_J]

If  NASA says potentially Wednesday, but SpaceX themselves say Thursday at the earliest - I think Wednesday is reeeeaaaly unlikely.

[Kabloona]

But it isn't "test fired" at all, which may be part of the reason for inspecting it again.

Yeah, I know. From my POV I can't think of any reason the anomaly shouldn't have been picked up at post-manufacture QC. Could it have been shipping? Could it have been vibration from the static test fire of the first stage? I'm not knowledgeable about it enough to make a good educated guess.

I'm not familiar with niobium nozzle extensions for liquid engines, but I do know that for solid upper stages like IUS and TOS that had large carbon-carbon one-piece nozzles, those things were extremely fragile, and damage during shipping, integration and stacking was always a concern. On the Mars Observer mission on Titan III, while stacked on the Titan, we did a final inspection of the TOS carbon-carbon nozzle just before closing out the Titan interstage, just to be sure that no damage had occurred during the final steps of vehicle integration. Apparently similar to what SpaceX did here. Point being, you can't be too careful with large, thin-walled, high expansion ratio nozzles, be they carbon-carbon or niobium, apparently. But it's not clear yet where/when the MVac nozzle defect occurred. "Porosity" in a weld suggests the manufacturing process, though.

[joshcryer]

SpaceXer twitter: A decision on whether or not to attempt launch on Wednesday is not expected until tomorrow.

edit, source: http://twitter.com/#!/SpaceXer/status/11955210863771648

Kabloona, thanks for that answer, btw.

[robertross]

But it's not clear yet where/when the MVac nozzle defect occurred. "Porosity" in a weld suggests the manufacturing process, though.

I would say 'clearly points to'.
The question becomes how it passed QA, as eluded to earlier in this thread. Depending on the QA procedures, one would 'think' that radiography of the welds would be in order, so this baffles me. Dye penetrant is another likely candidate, though I'm not sure if there would be any issues with contamination, but it's doubtful.

[Kabloona]

But it's not clear yet where/when the MVac nozzle defect occurred. "Porosity" in a weld suggests the manufacturing process, though.

I would say 'clearly points to'.
The question becomes how it passed QA, as eluded to earlier in this thread. Depending on the QA procedures, one would 'think' that radiography of the welds would be in order, so this baffles me. Dye penetrant is another likely candidate, though I'm not sure if there would be any issues with contamination, but it's doubtful.

It is puzzling...it suggests that they're taking fairly close-up hi-res photos in the interstage closeout process, and it's hard to imagine doing a more thorough inpection inside a dark, cramped interstage than they did in a brightly lit high bay back in Hawthorne...

[mmeijeri]

Hmm. We've already had a summer of leaks, are we now in for a winter of cracks?

[joshcryer]

Yeah, if you follow the discussion backward I was one of the first to mention QC. I wanted to reach out for alternate explanations. I hope we get an official root cause explanation in the coming days. SpaceX so far has been fairly open with that sort of thing (F1 failures, F9 spin start issue, and now this).

[KSC Engineer]

Right above the word SpaceX on their patch is a dragon which is their nomenclature and name for their spacecraft.   I was wondering if anyone knew the derivation of the dragon name, why they selected that name etc?  Just curious.

Really, I'm not kidding.

OK well if true here is what Wikipedia says about the song Puff the Magic Dragon: 

"The authors of the song have repeatedly rejected this urban legend and have strongly and consistently denied that they intended any references to drug use.[8] Peter Yarrow has frequently explained that "Puff" is about the hardships of growing older and has no relationship to drug-taking.[9] He has also said of the song that it "never had any meaning other than the obvious one" and is about the "loss of innocence".[10]"

[Jim]

Why is everyone dancing around it.  A process broke down.  Similar to something on the first F1 flight.

[Chris Bergin]

The other sites are only reporting what the media releases are saying. There's no inside track going on via twitter and other sites. As Jim says, way too much dancing around on this thread, and it's becoming noisey.

UPDATE: COTS 1

SpaceX engineers are analyzing the two small cracks in the aft end of the 2nd stage engine nozzle expansion.  A decision on whether or not to attempt launch on Wednesday is not expected until tomorrow.  The Merlin Vacuum engine expansion nozzle is made of a niobium alloy, measures 2.7 meters (9 feet) tall, and most of it has a wall thickness of about 1/3 of a millimeter.  The niobium nozzle increases the efficiency of the Merlin engine in vacuum, but is not necessary to ensure success on this mission.  (first stage engines do not have the extension)

UPDATE 2: COTS 1, more detail

 

SpaceX engineers are analyzing two small cracks in the aft end of the 2nd stage engine nozzle extension.  These cracks are in a region near the end of the nozzle extension where there is very little stress and so they would not cause a flight failure by themselves.  However, further investigation is warranted to ensure that these cracks are not symptomatic of a more serious problem. 

 

A decision on whether or not to attempt launch on Wednesday will be provided tomorrow evening. 

 

The bell shaped Merlin Vacuum nozzle extension is made of niobium sheet alloy, measures 9 feet tall and 8 feet at the base diameter, and thins out to about twice the thickness of a soda can at the end.  Although made of an exotic refractory alloy metal with a melting temperature high enough to boil steel, this component is geometrically the simplest part of the engine.

 

It is important to note that the niobium nozzle extension increases the efficiency of the Merlin engine in vacuum and is installed by default on all upper stage Merlin engines, but that efficiency increase is not required for this mission.  The nozzle extension is most helpful when launching very heavy satellites or to maximize throw mass to distant destinations like Mars.  The most likely path forward is that we will trim off the thinnest portion of the nozzle extension, which is where the cracks are located, perform a thorough systems check and resume launch preparation.

Both from SpaceX.

[joshcryer]

Thanks for the release Chris, first I've seen this anywhere. To be fair though we were discussing anomaly causes and QC, I was merely posting updates from SpaceX when I saw them, being clear that it was nothing new.

It'd be nice if the media would release these sort of releases as soon as they get them from SpaceX...

[robertross]

Anyone wishing to have a good read on Niobium's history & use in rocket nozzles:

http://www.cbmm.com.br/portug/sources/techlib/science_techno/table_content/sub_3/images/pdfs/016.pdf

[iamlucky13]

The most likely path forward is that we will trim off the thinnest portion of the nozzle extension, which is where the cracks are located, perform a thorough systems check and resume launch preparation.

Both from SpaceX.

Aha...the old 5-axis hand mill solution.

(Also known as an intern with a Dremel)

So, if I understand the thinking right, trimming off the affected portions eliminates stress concentrations that can aid the cracks in propogating further up the nozzle.

I would assume an imperfect trim could result in some moment across the nozzle, but that should be effectively negligible given the low pressures at this portion of the nozzle.

Aside from the small performance hit, any other concerns people see?

[robertross]

The most likely path forward is that we will trim off the thinnest portion of the nozzle extension, which is where the cracks are located, perform a thorough systems check and resume launch preparation.

Both from SpaceX.

Aha...the old 5-axis hand mill solution.

(Also known as an intern with a Dremel)

(laughed so hard at that one...)

So, if I understand the thinking right, trimming off the affected portions eliminates stress concentrations that can aid the cracks in propogating further up the nozzle.

I would assume an imperfect trim could result in some moment across the nozzle, but that should be effectively negligible given the low pressures at this portion of the nozzle.

Aside from the small performance hit, any other concerns people see?

considering the size of the nozzle from the press kit, the performance hit wouldn't even be detectable. More of a cosmetic change than anything else.

[Chris Bergin]

Thanks for the release Chris, first I've seen this anywhere. To be fair though we were discussing anomaly causes and QC, I was merely posting updates from SpaceX when I saw them, being clear that it was nothing new.

It'd be nice if the media would release these sort of releases as soon as they get them from SpaceX...

Yeah, sorry - that was my fault. I would normally post them as soon as I get them (into this sort of thread, as opposed to writing it up into an article, to speed things up). Was out at the time and came back to a frenzy

[KSC Engineer]

Why is everyone dancing around it.  A process broke down.  Similar to something on the first F1 flight.

Agreed Jim - fair amount of dancing going on here in several areas:   Political favoritism, low transparency on the part of SpaceX, pressure on the Range to make exceptions for SpaceX which are not granted to EELV or Shuttle, FAA waiver for Europe flyover, increased funding - during hard times in Washington - and I am sure there are other areas which you point out related to processing which you obviously have a lot of experience in.  This list is just a guess based on comments I've read here on L-2 so I could be wrong but I do see a lot of dancing going on.

Obviously SpaceX is getting a special deal out of WDC for now which is OK as we need them for ISS and I wish them the very best.  Poor planning on the part of congress over the years has caused a gap that has placed SpaceX in a challenging position to bail out part of the gap. 

Also I admire a man who puts up his own real cash to attempt to build a viable space program and he and his team has made very good progress in a short amount of time. 

So the reality is there is a lot of dancing going on and if I were in their shoes with the pressure WDC has placed on them maybe we all would be doing similar things.  All one has to do is watch the SpaceX team in their press conferences to realize how much pressure they are under. 

Whether folks like it or not the US needs SpaceX for now and thus the reason NASA was managing our expectations today by saying this is test program and they expect problems and they will continue to support SpaceX no matter what happens to the next two test flights.