Author Topic: ASDS OCISLY - with Thaicom-8 S1 - Return Coverage - May-June, 2016  (Read 492093 times)

Online Elmar Moelzer

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So the rotating "shoulder joint" of the grid fin is also covered in cork? It has the same color as the alleged cork on the interstage.

Offline Kabloona

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So the rotating "shoulder joint" of the grid fin is also covered in cork? It has the same color as the alleged cork on the interstage.

Probably. It's a flat surface to which cork can easily be bonded, unlike the grid fin itself which presumably is SPAMmed.

And here's another nice image from jardeon showing the clear difference between the substrates on the insterstage and stage 1. The interstage substrate shows the joint lines between the cork panels and is rougher than the aluminum substrate on stage 1.

Photo credit: jardeon.   https://m.imgur.com/gallery/2BWF8#
« Last Edit: 06/09/2016 12:52 pm by Kabloona »

Offline cookiejar5

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I uploaded the video of the tugs pushing the ASDS Ocisly up to the dock to you tube.

Offline AJW

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Here's my post after the Orbcomm 2 flight.  Maybe I should have stated that the person I asked was an engineer at SpaceX...


That's a good question.

To me, the significance of the soot is the implication that something unexpected (to us) was happening on or around the stage during its decent through the atmosphere. Depending on what is the root cause, it could have implications for performance or reliability. For example - is it (as some have speculated) a chilling effect from the LOX? Therefore does it indicate a flaw in the tank insulation or an indication of ice build-up during flight? Build up of frost could lead to issues like changes in the centre of gravity or asymmetric drag during the free-fall descent phase in between MECO3 and MES4.

I can't confirm, but asked a friend who dismissed the issue and said that he believes that a different paint is used beneath the SpaceX logo.
We are all interested in the future, for that is where you and I are going to spend the rest of our lives.

Offline Kabloona

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Here's my post after the Orbcomm 2 flight.  Maybe I should have stated that the person I asked was an engineer at SpaceX...


That's a good question.

To me, the significance of the soot is the implication that something unexpected (to us) was happening on or around the stage during its decent through the atmosphere. Depending on what is the root cause, it could have implications for performance or reliability. For example - is it (as some have speculated) a chilling effect from the LOX? Therefore does it indicate a flaw in the tank insulation or an indication of ice build-up during flight? Build up of frost could lead to issues like changes in the centre of gravity or asymmetric drag during the free-fall descent phase in between MECO3 and MES4.

I can't confirm, but asked a friend who dismissed the issue and said that he believes that a different paint is used beneath the SpaceX logo.

So that's two ex-SpaceXers seeming to confirm that the dark sooting/charring on the lower portion of the stage is due to a different type of paint/thermal coating as Herb has suggested.

Now we just need a tweet from Elon.  ;)
« Last Edit: 06/09/2016 02:51 pm by Kabloona »

Offline cscott

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Hey folks: SpaceX is a big place.  Not everyone at SpaceX is in a position to actually *know* the answers here.  If you have a SpaceX employee who says they "believe" or "think" something, sure give it a little more weight than some random user but not as much as Jim ;) or Elon.  Keep your minds open and consider all the evidence.  Even Elon has been wrong about (eg) ASDS operations, because he's not intimately involved with them.  Hans always gives disclaimers about the parts of the company he's not an authoritative source for.  Former employees are not different.

I'm convinced by some of the cork arguments, but if you maintain it's an ablative coating you have to explain how it can be washed clean.  I don't think that question has been adequately answered, and that was the observation which kicked off this thread.
« Last Edit: 06/09/2016 03:51 pm by cscott »

Offline Alastor

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"Washed clean" may just mean repainted/Replaced in this kind of context.

Let's look at the evidence we have :
Top part :
 - We have cork coloured stains around and above the grid fins after landing.
 - We have a different textures between the tank part and the fins part.
Bottom part :
 - We have peeled off (by Pad) charred material that obviously covers the metal and is cork coloured in its width.
 - We have the same but missing on landing.
 - We have a sudden change of the rivets pattern.
General :
 - We have different sections with different charring states on return (that may be due either to ice or to ablative material).
 - We know that cork has been used on F9 in the past.
Refitting experimentation :
 - We have a stage that was all charred up on return and that now looks clean, except the interstage.
Communication :
 - We have two (If I didn't miss anything) vague indications (from an ex-SpaceXer and a current SpaceXer) that there may be something going on at the top of the stage. Nothing actually affirmative but beliefs from people who probably have seen the F9 up close and may or may not know some things. (Few, this was tough to formulate ! Good luck for reading it ! It may take a few attempts)

Did I miss something ?

My interpretation of all these facts :
We have plenty of indications that there is Cork at both the Top and the bottom of the stage.
The fact that the stage now looks clean can mean that it was cleaned up, can mean that it was repainted, can mean that ablated materials were replaced, can (probably does to some extent !) mean any combination of all these different actions.

For me, there is definitely Cork or something vaguely resembling at both the top and bottom of the stage, and during the refitting experimentation, they cleaned up and either repainted or replaced these parts. Probably a bit of both. Obviously the parts where the paint didn't even come off don't need to be replaced. The charred parts ? It may depend on how much was ablated !

Offline Kabloona

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Hey folks: SpaceX is a big place.  Not everyone at SpaceX is in a position to actually *know* the answers here.  If you have a SpaceX employee who says they "believe" or "think" something, sure give it a little more weight than some random user but not as much as Jim ;) or Elon.  Keep your minds open and consider all the evidence.  Even Elon has been wrong about (eg) ASDS operations, because he's not intimately involved with them.  Hans always gives disclaimers about the parts of the company he's not an authoritative source for.  Former employees are not different.

I'm convinced by some of the cork arguments, but if you maintain it's an ablative coating you have to explain how it can be washed clean.  I don't think that question has been adequately answered, and that was the observation which kicked off this thread.

I wouldn't presume to call it an ablative coating since close-up photos seem to show the SpaceX logo intact under the "soot" and we don't see any areas where it has burned off or otherwise charred. It looks like glossy white paint over aluminum (on the first stage, not the interstage) before launch, and it looks like glossy white paint after cleanup. if there was any ablation, it shouldn't still be glossy after cleanup.

But it does seem to be different somehow from the white paint on the top 2/3, since there is that clear delineation between the dark sooting below and the light sooting above, and the comments from the ex-SpaceXers support the notion that the "paint" down there is somehow different.
« Last Edit: 06/09/2016 04:43 pm by Kabloona »

Offline the_other_Doug

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...from CRS-8, the jagged brown cork edges are visible around the missing area where we can see gray aluminum beneath the cork at the base of the stage. Here too, the joint lines between cork panels are evident.

Thank you!  This, in particular, is the area on the CRS-8 booster that convinced me there is an insulation layer beneath the paint on at least the lower portion of the F9 first stages.  If that's not cork insulation, it's something that has been painstakingly designed to look and have the physical characteristics (i.e., the jagged way it tears) of a cork layer.  Occam's Razor suggests it is, indeed, a cork layer.

I also think Herb has a point, and it again matches some things I've noticed and commented on -- on a couple of the recovered boosters, I think the insulation layer (NOT, please read and understand NOT, the metal structure of the stage or tanks, as people keep mis-reading my posts and accusing me of saying), JUST the insulation layer, shows some interesting erosion patterns, cracking, and slumping.

Since I am quite certain the stages don't see enough heating to cause anything like this kind of effect on just painted aluminum, I've been of the opinion for quite some time that these are surficial heating effects in the insulation layer, and likely can be repaired easily by a simple removal and re-application of affected areas of the insulation.  The fact that, at least on CRS-8, it was possible for a worker to just tear the stuff off by hand means it can't be that hard to remove and re-apply.

It looks like the cleaned-up stage sitting in the hangar at 39A has had at least some of its insulation layer replaced -- but since you only get a good look at the interstage end in the image in question, it's hard to say...
-Doug  (With my shield, not yet upon it)

Offline cscott

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"Washed clean" may just mean repainted/Replaced in this kind of context.

Nope.  The necessary equipment is not present at the Cape.  We've seen the paint booth at Hawthorne.  It's big.  It's not hiding somewhere.

If insulation was replaced, it would only be on small areas where touchup paint could be applied, like we say on the interstage spots. Perhaps below the legs. Certainly not on the whole core.  (Others also agree that most of the S1 core has the texture and rivets of smooth aluminum-lithium allow, not the panel and grain of cork.)

- We have cork coloured stains around and above the grid fins after landing.

*Allegedly* cork-colored.  To my eye it still looks like carbonized hydraulic fluid.  You can see on some of the other pictures what it looks like when the paint on the interstage gets worn away, and (IMO) it doesn't look anything like the area above the grid fins.  "Paint burned away" tends to have a much choppier outline, as the paint seems to flake in fairly large pieces.
« Last Edit: 06/09/2016 05:19 pm by cscott »

Offline Lar

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Hey folks: SpaceX is a big place.  Not everyone at SpaceX is in a position to actually *know* the answers here.  If you have a SpaceX employee who says they "believe" or "think" something, sure give it a little more weight than some random user but not as much as Jim ;) or Elon.  Keep your minds open and consider all the evidence.  Even Elon has been wrong about (eg) ASDS operations, because he's not intimately involved with them.  Hans always gives disclaimers about the parts of the company he's not an authoritative source for.  Former employees are not different.

I'm convinced by some of the cork arguments, but if you maintain it's an ablative coating you have to explain how it can be washed clean.  I don't think that question has been adequately answered, and that was the observation which kicked off this thread.

I wouldn't presume to call it an ablative coating since close-up photos seem to show the SpaceX logo intact under the "soot" and we don't see any areas where it has burned off or otherwise charred. It looks like glossy white paint over aluminum (on the first stage, not the interstage) before launch, and it looks like glossy white paint after cleanup. if there was any ablation, it shouldn't still be glossy after cleanup.

But it does seem to be different somehow from the white paint on the top 2/3, since there is that clear delineation between the dark sooting below and the light sooting above, and the comments from the ex-SpaceXers support the notion that the "paint" down there is somehow different.
Don't forget to take the tank boundary (and the difference in temperature/ice level) into account when evaluating cork/non corkness...

I have a question about cork, is it natural or synthetic? If natural, is it cut from trees and processed into sheets the way plywood/veneer layers are? or is it pulverized and formed into sheets the way particle board is?
« Last Edit: 06/09/2016 08:21 pm by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline ClayJar

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I have a question about cork, is it natural or synthetic? If natural, is it cut from trees and processed into sheets the way plywood/veneer layers are? or is it pulverized and formed into sheets the way particle board is?

Amorim Cork Composites makes cork TPS products.  They're made of cork particles on the order of a millimeter, with a special binder for high heat resistance.  (Made into sheets, naturally.)

http://www.amorimcorkcomposites.com/industry.php/product_board/?brand=34&pl=45

Offline Johnnyhinbos

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Only here would you ever find such a conversation.

#Corkgate2016
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline Lars-J

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So the rotating "shoulder joint" of the grid fin is also covered in cork? It has the same color as the alleged cork on the interstage.

Probably. It's a flat surface to which cork can easily be bonded, unlike the grid fin itself which presumably is SPAMmed.

And here's another nice image from jardeon showing the clear difference between the substrates on the insterstage and stage 1. The interstage substrate shows the joint lines between the cork panels and is rougher than the aluminum substrate on stage 1.

Photo credit: jardeon.   https://m.imgur.com/gallery/2BWF8#

First, not everything that has a brown or rust appearance after re-entry has to be cork.
Yes, It is possible that The interstage and/or base below legs has some cork TPS. But the main tank surface, with all the tiny rivets visible? *Unlikely*. Very unlikely.

And despite now us seeing the tank sides washed clean (not clean like new), people are now suggesting that cork TPS has been re-applied and/or repainted?  #CorkTruthers ;)
« Last Edit: 06/09/2016 10:51 pm by Lars-J »

Offline Kabloona

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And despite now us seeing the tank sides washed clean (not clean like new), people are now suggesting that cork TPS has been re-applied and/or repainted?  #CorkTruthers ;)

No, actually I've admitted with the photo I posted above that the photo seems to show the clear difference between the interstage substrate  (cork) and the first stage substrate (metal), so I'm won over to the "painted aluminum" argument for stage one, except for the cork at the base of the stage below the legs.  :)

Here it is again.

« Last Edit: 06/09/2016 11:44 pm by Kabloona »

Offline Herb Schaltegger

Let's keep this in context - this whole #CorkGate business started when people insisted that sharp color distinction was due to "soot deposition" during entry and/or landing burns. I and a few others disagreed; personally, I asserted that soot particle deposition under conditions of highly turbulent fluid flow would be very unlikely to result in such sharply-defined color differences across parts of the stage as observed in the returned examples, ice or no ice. I suggested some type of TPS or ablative coating that was becoming discolored during entry/landing. I think evidence has only mounted with each flight that there is indeed some degree of TPS being used around the base, grid fins, and now possibly (probably?) over the surfaces of the composite interstage.

Specific details of what that material is, where exactly it is and is not applied with regard to under legs, everywhere around the base BUT under the legs, around the interstage, etc. is still open to continuing debate in my mind. But at this point, the fact that some kind of TPS is being used is really not. For the sake of discussion, let's just call that putative TPS "cork" until we have a better word, shall we? ;)

Along those lines, it's quite likely that stages are being wiped down post-flight to remove surface dirt and soot, while at the same time leaving the cork and/or painted metallic parts underneath still thermally discolored. If reuse becomes a regular thing, I think we are likely to get used to seeing dirty rockets launching payloads in a few years. At least until SpaceX puts a paint booth on-site.
« Last Edit: 06/09/2016 11:43 pm by Herb Schaltegger »
Ad astra per aspirin ...

Offline Kabloona

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To summarize, IMHO this is the current state of "TPS" knowledge/theory, though I know opinions will always differ:

1. base of stage clearly has cork panels covering the areas aft of legs
2. Lower third of stage probably has some special paint/coating over the aluminum that causes the dark coloration (sooting? charring?) that Herb has discussed. Two former SpaceXers seem to have confirmed this idea of a different paint/coating on the lower third or so.
3. Interstage has clear evidence of being entirely covered in cork (rough substrate, brown mottled coloration consistent with cork where paint has been lost during reentry).

Edit: changed "charring" to "dark coloration"
« Last Edit: 06/10/2016 12:20 am by Kabloona »

Offline envy887

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How do reconcile point 2 with the fact that the paint on Orbcomm-2 stage is no longer "charred", even though there's no paint booth at the HIF?

Offline Kabloona

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How do reconcile point 2 with the fact that the paint on Orbcomm-2 stage is no longer "charred", even though there's no paint booth at the HIF?

I should have called it "dark coloration" rather than charring. I just edited the post accordingly. I tend to think it's more like sooting. Herb may still think it's charring. But I agree it seems to have cleaned up too well to be charring.
« Last Edit: 06/10/2016 12:19 am by Kabloona »

Offline virnin

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Along those lines, it's quite likely that stages are being wiped down post-flight to remove surface dirt and soot, while at the same time leaving the cork and/or painted metallic parts underneath still thermally discolored. If reuse becomes a regular thing, I think we are likely to get used to seeing dirty rockets launching payloads in a few years. At least until SpaceX puts a paint booth on-site.

I know the surface area of the F9 first stage is smaller than an STS ET but I still wouldn't want to be adding a layer of new paint per flight.  And I would likely NOT entertain removing the flown paint via either chemical or physical methods prior to repainting because you just never know what kind of incidental, hidden damage could occur.  I wouldn't be gung-ho about removing and replacing "cork" either if it could be avoided.

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