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Aethon

By Aethon
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CatastrophicFailure

CatastrophicFailure

Posted
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And some critical new information, too:

Quote

The recovered COPVs showed buckles in their liners," SpaceX said Monday in its update. "Although buckles were not shown to burst a COPV on their own

at least I've never heard it before. According to the article, such buckles are a natural place for solid LOx to condense. Additionally, it sounds like SpaceX had been trying something slightly different with the fueling procedure on that static fire. 

If all this is correct, it goes back to some observations brought up months ago, that this failure was a result of a combination of circumstances never seen or considered before. Hindsight is always 20/20. 

The long term solution is to eliminate buckles in the COPV tanks. I forget if SX makes these in house, but given that they're planning to use some MASSIVE composite tanks on their BFR, this is definitely something to get right. Short term is simply to change the fueling procedure to avoid solid oxygen formation. Sound pretty reasonable to me. 

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StrandedonEarth

StrandedonEarth

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3 hours ago, CatastrophicFailure said:

Additionally, it sounds like SpaceX had been trying something slightly different with the fueling procedure on that static fire. 

Early on in the investigation, one article or another hinted at this, that they were tweaking the procedure to try to increase the pad loiter time to handle minor delays. Someone called me on it when I mentioned that they shouldn't experiment when other people's payloads are attached, and then I couldn't find the article. So this re-affirms my comment. Trying to dig through tens of pages of comments to find the link to the right article was a daunting task that I didn't have time for.

Murphy's Law was just waiting for an opportunity to strike.

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YNM

YNM

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Some useful illustrations in there regarding the COPV thing.

And yes, if they don't fix this, it's not a good lookout. Though I suppose it's quite easy to fix them - perhaps the material will be more problematic.

EDIT : From that article (my emphasis) :

Quote

The investigation identified several "credible causes" for this failure, all of which can be avoided in the short term by changing the COPV configuration to allow for the loading of warmer helium, and returning helium loading procedures to a "prior flight proven configuration." Presumably this means prior to December 2015, when the company began using supercooled liquid oxygen and kerosene fuels to increase the performance of its rocket, known as the Falcon 9 Full Thrust vehicle. Since the accident did not involve the rocket fuels themselves, Ars understands that the new procedures will not substantially affect the performance gains of the full thrust Falcon 9 for upcoming launches.

 

Edited by YNM
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Racescort666

Racescort666

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On 12/30/2016 at 6:25 PM, StrandedonEarth said:

 

Is that an older pic? It looks the Shuttle's RSS is still there, or are they just leaving it there?

0ns4eFY.jpg

The Shuttle RSS is still there. I took this picture 2 days ago. The strong back is there but it's hard to see with the fence in the way. 

I was super pumped about going to Kennedy Space Center, it was amazing.

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cubinator

cubinator

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Looks like we've got a time for the Iridium NEXT launch:

http://spaceflightnow.com/launch-schedule/

18:22 GMT

Edit: apparently they were planning to use a veteran booster for this launch:

http://spacenews.com/spacex-to-launch-ses-10-satellite-on-reused-falcon-9-by-years-end/

Note that this was before the September explosion, so I don't know if that plan has changed.

Edited by cubinator
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Kryten

Kryten

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21 minutes ago, cubinator said:

Edit: apparently they were planning to use a veteran booster for this launch:

http://spacenews.com/spacex-to-launch-ses-10-satellite-on-reused-falcon-9-by-years-end/

Note that this was before the September explosion, so I don't know if that plan has changed.

Iridium's agreement is for all new cores for their flights. SES are a geostationary sat operator, they have no connection to this launch or to iridium.

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StrandedonEarth

StrandedonEarth

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A very recent article stated that SpaceX has a customer lined up for an experienced booster, which was previously announced as SES. So not this time.

According to http://spaceflightnow.com/launch-schedule/, SES 10 is slated for February (exact date TBD). That should be an experienced booster, although it doesn't specifically say so.

Edited by StrandedonEarth
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cubinator

cubinator

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10 hours ago, Kryten said:

Iridium's agreement is for all new cores for their flights. SES are a geostationary sat operator, they have no connection to this launch or to iridium.

 

10 hours ago, StrandedonEarth said:

A very recent article stated that SpaceX has a customer lined up for an experienced booster, which was previously announced as SES. So not this time.

According to http://spaceflightnow.com/launch-schedule/, SES 10 is slated for February (exact date TBD). That should be an experienced booster, although it doesn't specifically say so.

Understood.

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TheEpicSquared

TheEpicSquared

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RTF postponed to Jan 14th due to bad weather, unfortunately.

http://www.spaceflightinsider.com/organizations/space-exploration-technologies/spacex-falcon-9-rtf-postponed-to-jan-14/

10 hours ago, StrandedonEarth said:

According to http://spaceflightnow.com/launch-schedule/, SES 10 is slated for February (exact date TBD). That should be an experienced booster, although it doesn't specifically say so.

Spaceflightnow says Feb 8th now for SES 10. 

Actually, ignore that, it's CRS 10 that launches on Feb 8th, not SES 10. Whoops :P  

Edited by TheEpicSquared
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WuphonsReach

WuphonsReach

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1 hour ago, StrandedonEarth said:

IIRC they did a barge landing from Vandenberg. I think environmentally sensitive areas are making it difficult to get permission to return to dry land. 

They attempted a barge landing for the Jason-3 launched from Vandy about a year ago.  This is the one where the leg lockout failed to engage and the first stage tipped over after a successful landing.

 

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Wjolcz

Wjolcz

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What's the hold-down firing? Do they actually fire the engines with the payload already attached? I would assume the firing takes place at 30% of thrust or something like that just to test if everything is fine and not to overstress the rocket's structure?

Also how will the FH ascend profile look like? I would imagine it will simply have higher initial TWR. The outter cores will separate and be able to go back to perform touch-down on land and the middle core will have more fuel to put the heavier payload in orbit and land on the barge with more or less the same speed it lands with during LKO missions (assuming the mission itself is LKO).

Edited by Veeltch
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Steel

Steel

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Posted (edited)
29 minutes ago, Veeltch said:

What's the hold-down firing? Do they actually fire the engines with the payload already attached? I would assume the firing takes place at 30% of thrust or something like that just to test if everything is fine and not to overstress the rocket's structure?

Hold down firing is what you'd imagine it to be. AFAIK they test at full thrust, partly as a test and partly because even the Merlin engines, which have quite a large throttle range, can only throttle to about 70% of max thrust.

30 minutes ago, Veeltch said:

Also how will the FH ascend profile look like? I would imagine it will simply have higher initial TWR. The outter cores will separate and be able to go back to perform touch-down on land and the middle core will have more fuel to put the heavier payload in orbit and land on the barge with more or less the same speed it lands with during LKO missions (assuming the mission itself is LKO).

The plan for FH, at least initially, is to only recover the booster cores, not the centre core (don't quote me on that, it might be the other way around, but they're not planning to recover all three)

Edited by Steel
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Streetwind

Streetwind

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45 minutes ago, Veeltch said:

What's the hold-down firing? Do they actually fire the engines with the payload already attached? I would assume the firing takes place at 30% of thrust or something like that just to test if everything is fine and not to overstress the rocket's structure?

Also how will the FH ascend profile look like? I would imagine it will simply have higher initial TWR. The outter cores will separate and be able to go back to perform touch-down on land and the middle core will have more fuel to put the heavier payload in orbit and land on the barge with more or less the same speed it lands with during LKO missions (assuming the mission itself is LKO).

A static fire test is sort of a dress rehearsal for launch. You go through the countdown as you normally would, all the way to spooling the engines up to flight thrust; the only difference is, the holddown clamps are never released. There's no fixed definition of how it goes down, though. SpaceX does one before every launch. Other companies do a few before the first launch of a new vehicle, and then never again. Others still do their dress rehearsals without engine ignition. And everyone's process is different as well. The decision of how and when lies with each launch vehicle operator individually - depending on what they consider necessary.

Because SpaceX has decided to do one before every launch, they eventually started attaching the payload before the test, in order to save time. If you roll out the rocket without a payload for the test, then you have to roll it back into the hangar and attach the payload, then roll it back out to the pad. This can take 3-4 days. Meanwhile, if you attach the payload and then roll it out for the test, you can just leave the rocket on the pad and launch soon after. SpaceX typically launches less than 48 hours after their static fire, assuming no problems were found and weather permits. Sometimes a lot less than 48 hours.

 

Your assumptions regarding Falcon Heavy are largely correct, with one exception: the center core will be going much faster than a F9 returning from a LEO mission (careful with those KSP terms, btw :P). Even if Falcon Heavy goes to LEO, its center core will be going at least as fast, if not faster, than a F9 core going to GTO. Not sure if it was Elon Musk himself who said it, but I believe the words "really hauling ass" were thrown around. I assume they'll combat that with longer boostback and reentry burns, but it'll still be the most aggressive return they'll have flown.

 

15 minutes ago, Steel said:

...even the Merlin engines (...) can only throttle to about 70% of max thrust.

This was true for the original Merlin 1D. But the engine has been uprated in max thrust so much since then, the throttle point is now closer to 30%-40% :wink:

 

Edited by Streetwind
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TheEpicSquared

TheEpicSquared

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18 minutes ago, Steel said:

The plan for FH, at least initially, is to only recover the booster cores, not the centre core (don't quote me on that, it might be the other way around, but they're not planning to recover all three)

Really? I thought they were going to land the boosters back on land, and the core on the ASDS.  

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