Author Topic: Refurbishment of Used Stages/Vehicles  (Read 212843 times)

Offline mvpel

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Re: Refurbishment of Used Stages/Vehicles
« Reply #220 on: 04/17/2016 01:47 AM »
Not to put too fine a point on it, but... the same could be said of almost any engine... rocket, aircraft or automotive.
Except for engines which smash into the ocean after each use, needless to say.

Quote
The question is not: Will additional inspection-refurbishment-rebuild of various components be required; but: How often and at what cost?  IMHO, I hope and expect that SpaceX has done their homework, engineered appropriately, and that inspection-refurbishment-rebuild is cost effective.  And if not, I hope and expect they will make improvements to make them cost effective.

In any case, too early to tell.
I would beg to differ. They recovered, inspected, and static-fired the ORBCOMM-2 core, and declared it ready to refuel and refly. That one will be shipped to Hawthorne instead and put on display, but they anticipate reflying the CRS-8 booster within about two months, they said. Even single reuse of a single core that represents 70% of the cost of the rocket - as they've said - has a very large impact on the cost of your launch, and you'd need one hell of a lot of recovery and refurbishment spending to get up to 35% of the cost of the vehicle.
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Offline sewebster

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Re: Refurbishment of Used Stages/Vehicles
« Reply #221 on: 04/17/2016 04:26 AM »

I would beg to differ. They recovered, inspected, and static-fired the ORBCOMM-2 core, and declared it ready to refuel and refly.

Maybe I missed it, but didn't they have thrust fluctuations during the static fire and that was the last we heard about it?

Online meekGee

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Re: Refurbishment of Used Stages/Vehicles
« Reply #222 on: 04/17/2016 05:29 AM »
Elon Musk has stated they have no meaningful limit. They just need exchange of some highly stressed parts.

Not to put too fine a point on it, but... the same could be said of almost any engine... rocket, aircraft or automotive.

The question is not: Will additional inspection-refurbishment-rebuild of various components be required; but: How often and at what cost?  IMHO, I hope and expect that SpaceX has done their homework, engineered appropriately, and that inspection-refurbishment-rebuild is cost effective.  And if not, I hope and expect they will make improvements to make them cost effective.

In any case, too early to tell.

You can always distort meanings...   For example, if the body reaches its fatigue life in 5 flights, you can "refurbish it" by replacing the body.

But that's not what he's saying.

He's saying the goal is to fly 10-20 times, then do an economically sensible refurbishment (i.e. replace some components, and possibly refurbish them) and keep flying till ~100, where it becomes economically impractical to "refurbish" any further.

The nice thing is that these numbers are meaningless until both reliability and flight volume increase significantly.

This implies that their plans are as grandiose as we think/hope. (or that they are complete and utter fools, designing a rocket that will never be used)

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Offline Avron

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Re: Refurbishment of Used Stages/Vehicles
« Reply #223 on: 04/17/2016 01:23 PM »
just wondering how clean they can get the stage before re-fly without a repaint. Dark stage will mean more heating, while sitting on the pad

Offline AncientU

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Re: Refurbishment of Used Stages/Vehicles
« Reply #224 on: 04/17/2016 02:01 PM »

I would beg to differ. They recovered, inspected, and static-fired the ORBCOMM-2 core, and declared it ready to refuel and refly.

Maybe I missed it, but didn't they have thrust fluctuations during the static fire and that was the last we heard about it?

They did.  Changes were made to subsequent vehicles based on what was found on that flight per link below.
That stage is heading to Hawthorne for suitable lawn ornamentation.

http://forum.nasaspaceflight.com/index.php?topic=39167.msg1487298#msg1487298

The ten sequential firings on this CRS-8 stage will show if issue is resolved.
« Last Edit: 04/17/2016 02:02 PM by AncientU »
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Offline mvpel

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Re: Refurbishment of Used Stages/Vehicles
« Reply #225 on: 04/17/2016 02:51 PM »
The change was minor, from what I was told. Probably not subject to open discussion due to ITAR.


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Offline AncientU

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Re: Refurbishment of Used Stages/Vehicles
« Reply #226 on: 04/17/2016 03:36 PM »
The change was minor, from what I was told. Probably not subject to open discussion due to ITAR.


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Brief response that carries significant implications:
SpaceX is already making reliability improvements based on the very first recovered stage.  This bodes well for refurbishment, reuse, launch cost, ...
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Online AC in NC

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Re: Refurbishment of Used Stages/Vehicles
« Reply #227 on: 04/18/2016 02:53 AM »
Lots of pictures posted on the OCISLY Return thread.  This one caught my eye at the last picture on this post.

Was wondering (on another probably the wrong thread) about a more significant dedicated refurbishment facility.  Here is an awful lot of steel beams sitting out getting rusty within spitting distance of the Falcon.  Hmmm.




Online Brovane

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Re: Refurbishment of Used Stages/Vehicles
« Reply #228 on: 04/18/2016 03:09 AM »
Elon Musk has stated they have no meaningful limit. They just need exchange of some highly stressed parts.

Not to put too fine a point on it, but... the same could be said of almost any engine... rocket, aircraft or automotive.

The question is not: Will additional inspection-refurbishment-rebuild of various components be required; but: How often and at what cost?  IMHO, I hope and expect that SpaceX has done their homework, engineered appropriately, and that inspection-refurbishment-rebuild is cost effective.  And if not, I hope and expect they will make improvements to make them cost effective.

In any case, too early to tell.

Considering how SpaceX uses "Sparse Matrix" to make their engineering decisions.  I suspect that they don't have all the answers.  Part of their conversation is probably along the lines of "Let's get a few cores back see what condition they are in."  Unlike some aerospace companies they don't look at every possibility before making a decision and moving ahead.  They will continue to refine the Falcon-9 as they get more cores back and test fire them and discovery issues that come up.  All of this testing will make the Falcon-9 a more dependable launch vehicle.   
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Offline IntoTheVoid

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Re: Refurbishment of Used Stages/Vehicles
« Reply #229 on: 04/18/2016 06:10 AM »
Lots of pictures posted on the OCISLY Return thread.  This one caught my eye at the last picture on this post.

Was wondering (on another probably the wrong thread) about a more significant dedicated refurbishment facility.  Here is an awful lot of steel beams sitting out getting rusty within spitting distance of the Falcon.  Hmmm.

From earlier in that thread...

FYI, the fence behind the structural steel has been the "property line" for SpaceX's space since they moved to Port Canaveral.  Apparently they got permission from the neighbors to put their anchor block on the foreground side of the fence.  I don't believe the steel has anything to do with SpaceX.

Online AC in NC

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Re: Refurbishment of Used Stages/Vehicles
« Reply #230 on: 04/18/2016 12:34 PM »
From earlier in that thread...

So much material to read ... 

grrrr.  :-[ Thanks.

Offline 411rocket

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Re: Refurbishment of Used Stages/Vehicles
« Reply #231 on: 04/18/2016 12:55 PM »
Looking on the Port webcam, looks like someone decided, to cleanup one of the engine nozzles, at least on the outside. Sure is a big contrast, to another visible nozzle.

Offline Paul_G

Re: Refurbishment of Used Stages/Vehicles
« Reply #232 on: 04/18/2016 05:29 PM »
From earlier in that thread...

So much material to read ... 

grrrr.  :-[ Thanks.

That does beg the question, when that structure is built, and the adjacent site operational, will SpaceX need to move their stand, so that they have space to place the concrete block securing the tie-down, or will the process evolve sufficiently that the stage won't be on the stand long enough to warrant the tiedown.

Paul

Online Lar

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Re: Refurbishment of Used Stages/Vehicles
« Reply #233 on: 04/20/2016 01:13 AM »
the gorgeous pics by StockHolder in the ASDS OCISLY thread starting here https://forum.nasaspaceflight.com/index.php?topic=40002.msg1521175#msg1521175 make me think about consumables. We already saw that some of the corkage got beat up. I thought I saw erosion in both sets of grid fins that have been returned. 

Can we start to predict some of the things that are going to be consumables, and others that are going to be redesigned not to wear as much?

I'm thinking grid fins would get heavier if they were strengthened so much that they resisted most of the erosion we saw. So they might be a consumable.

On the other hand refitting cork each time seems time consuming so that may be a redesigned area with a different material? or a strengthened surface but cork still there?
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Offline Kabloona

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Re: Refurbishment of Used Stages/Vehicles
« Reply #234 on: 04/20/2016 02:22 AM »
Quote
On the other hand refitting cork each time seems time consuming so that may be a redesigned area with a different material? or a strengthened surface but cork still there?

Those cork composite panels should not be difficult nor time consuming to re-apply, at least compared to something like Shuttle tiles. But I'm guessing the main change next time around might be to improve the bonding process. Looks like the adhesive simply didn't hold. Maybe the substrate prep was inadequate, or not enough adhesive was used.

Either way, I'm betting next time around we don't see any missing cork chunks.

As for the grid fins, the closeups on the OG2 stage seemed to show that the erosion was in the surface TPS material, not the metal itself. Reapply TPS as needed, and fly again.
« Last Edit: 04/20/2016 02:24 AM by Kabloona »

Offline Herb Schaltegger

Re: Refurbishment of Used Stages/Vehicles
« Reply #235 on: 04/20/2016 02:31 AM »
I think there's not much doubt any longer about why the bottom third or so of the stage is so dark compared to the upper portions, after these closeup views. At the very least I expect the white paint will be reapplied for direct thermal control purposes pre-launch due to color, and to sacrifically ablate away during flight to help protect the cork surface. I suspect they may change paint formulations, however, as they learn how to reprocess stages.
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Offline CJ

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Re: Refurbishment of Used Stages/Vehicles
« Reply #236 on: 04/20/2016 03:34 AM »
I think there's not much doubt any longer about why the bottom third or so of the stage is so dark compared to the upper portions, after these closeup views. At the very least I expect the white paint will be reapplied for direct thermal control purposes pre-launch due to color, and to sacrifically ablate away during flight to help protect the cork surface. I suspect they may change paint formulations, however, as they learn how to reprocess stages.

I'm a bit confused; if we're talking the area that's currently very dark due to soot (bottom 1/3 of the stage) why paint it white? Is there really a need for the thermal benefit of white paint over the RP1 tank? Or is it a thermal conductance issue?
I have a feeling I'm missing something here.

Hrmmm... radiative heating due to recirculation during ascent? I'm guessing that's fairly severe.

Offline Kabloona

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Re: Refurbishment of Used Stages/Vehicles
« Reply #237 on: 04/20/2016 02:37 PM »
On the subject of used engines, Elon tweeted a pic of the two returned cores in the high bay. The OG2 stage has several engines removed, and it's instructive to compare the photo with a sketch I made previously, just after the OG2 stage had come back and we were able to see pics.

We saw from the pics that outer engines #1 and #5 had visible TEA/TEB residue, making it likely that those were the two engines, in addition to the center engine, that comprised the 3-engine restart "triad." So I had double-circled those in the sketch as the probable "restartable" engines.

And now this pic from Elon shows those three engines (#1, #5, #9) missing, which tends to support the hypothesis that those are, in fact, the restartable engines. (The other missing engines are #4 and #7).

Will be interesting to hear what they find from inspections.
« Last Edit: 04/20/2016 02:51 PM by Kabloona »

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Re: Refurbishment of Used Stages/Vehicles
« Reply #238 on: 04/20/2016 02:55 PM »
Kabloona are you sure the rotation is the same? I see your marks (fluid connections, the flag, etc) but my eyes aren't good enough to tell that from the image of both stages... to my way of thinking the leg marks show that there was some rotation... the pair of engines still there are either 3 and 4 or maybe 7 and 8 in your sketch, but I can't spot the white rectangle and may be confused.
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Offline Kabloona

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Re: Refurbishment of Used Stages/Vehicles
« Reply #239 on: 04/20/2016 02:57 PM »
Kabloona are you sure the rotation is the same? I see your marks (fluid connections, the flag, etc) but my eyes aren't good enough to tell that from the image of both stages... to my way of thinking the leg marks show that there was some rotation... the pair of engines still there are either 3 and 4 or maybe 7 and 8 in your sketch, but I can't spot the white rectangle and may be confused.

It looks to have been rolled slightly clockwise. You can see by comparing the location of the black lifting pin fittings at the top and bottom. But the roll is not significant enough to have thrown off my engine numbering, IMO. In the pic below, engine #1 is almost at the top, at about the  12:30-o'clock position. In the pic above, it has been rotated to the 1-o'clock position.
« Last Edit: 04/20/2016 03:15 PM by Kabloona »

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