Author Topic: Starship heat shield  (Read 1061283 times)

Offline Nomadd

  • Senior Member
  • *****
  • Posts: 8572
  • Highway Whatever
  • Liked: 58380
  • Likes Given: 1140
Re: Starship heat shield
« Reply #3280 on: 11/28/2022 11:52 am »
A couple of fin fairings and a piece of something that I'm not sure about sitting out back.

It looks like the frames of the tiles stick out on the sides.

The frames use to be shorter and completely buried. They were where most of the ones I saw failed.
They were three separate pieces instead of Ys originally. I'm not sure about these.
« Last Edit: 12/02/2022 04:56 am by Nomadd »
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline Tangilinear Interjar

  • Full Member
  • **
  • Posts: 296
  • California
  • Liked: 523
  • Likes Given: 19
Re: Starship heat shield
« Reply #3281 on: 11/29/2022 03:01 pm »
Regarding the visible mounting support in those tiles; my money is on there being a standard sintered tile part that's probably the exact size of the main hex tiles. That component is either coated and baked to make a standard tile or it's machined to a smaller size or different shape for the other tiles as a secondary process before being coated and baked.

These particular tiles are small enough that the metal was cut exposed on the edges and for whatever reason the glass coating doesn't adhere to the metal well.

From a manufacturability perspective having a single high production process that makes all the tile blanks and then customizing just a few makes the most sense.

As for the little bit of exposed metal, I doubt that it matters considering where it is and that it's edge on.

Online InterestedEngineer

  • Full Member
  • ****
  • Posts: 949
  • Seattle
  • Liked: 768
  • Likes Given: 1144
Re: Starship heat shield
« Reply #3282 on: 11/29/2022 04:49 pm »
As for the little bit of exposed metal, I doubt that it matters considering where it is and that it's edge on.

Stainless steel can handle the temperatures the tile requires without melting (1250degC).

That temperature does dramatically reduce SS strength - permanently.  But a lot of strength is not needed, the tiles are already extremely fragile.

So exposed metal doesn't matter much.

Online edzieba

  • Virtual Realist
  • Senior Member
  • *****
  • Posts: 4899
  • United Kingdom
  • Liked: 7121
  • Likes Given: 36
Re: Starship heat shield
« Reply #3283 on: 11/30/2022 09:39 am »
Regarding the visible mounting support in those tiles; my money is on there being a standard sintered tile part that's probably the exact size of the main hex tiles. That component is either coated and baked to make a standard tile or it's machined to a smaller size or different shape for the other tiles as a secondary process before being coated and baked.

These particular tiles are small enough that the metal was cut exposed on the edges and for whatever reason the glass coating doesn't adhere to the metal well.

From a manufacturability perspective having a single high production process that makes all the tile blanks and then customizing just a few makes the most sense.

As for the little bit of exposed metal, I doubt that it matters considering where it is and that it's edge on.
From the FDEP report on the tile manufacturing facility: The tile billets are moulded, then sintered, then cut in half face-to-face or back-to-back (i.e. billets are double-thickness), then trimmed to size, then the RCG coating is applied (with further heating).

Online equiserre

  • Full Member
  • *
  • Posts: 171
  • Liked: 231
  • Likes Given: 30
Re: Starship heat shield
« Reply #3284 on: 11/30/2022 09:44 pm »
A couple of fin fairings and a piece of something that I'm not sure about sitting out back.

Great photos, Nomadd! the fin fairing tiles seem to be of a completely different design from the main body tiles?  And no red adhesive is to be seen. Can someone sum up what they are and how are they attached?

Online edzieba

  • Virtual Realist
  • Senior Member
  • *****
  • Posts: 4899
  • United Kingdom
  • Liked: 7121
  • Likes Given: 36
Re: Starship heat shield
« Reply #3285 on: 12/01/2022 08:04 am »
A couple of fin fairings and a piece of something that I'm not sure about sitting out back.

Great photos, Nomadd! the fin fairing tiles seem to be of a completely different design from the main body tiles?  And no red adhesive is to be seen. Can someone sum up what they are and how are they attached?
SpaceX switched from red RTV to white some months ago (either a switch in formulation, or just a big enough order they could request a different pigment). They've also gotten better at applying it without as much smear.

Offline su27k

  • Senior Member
  • *****
  • Posts: 6266
  • Liked: 8861
  • Likes Given: 870
Re: Starship heat shield
« Reply #3286 on: 12/24/2022 03:03 am »
Not sure if this has been posted before or not, old news from 2021, seems likely this is related to Starship heat shield: SpaceX wins Air Force manufacturing research contract for hypersonic vehicle thermal shields

Quote from: SpaceNews
The Air Force Research Laboratory awarded SpaceX an $8.5 million contract to investigate advanced materials and manufacturing techniques for heat shields that protect hypersonic vehicles in flight.

Heat protection is a critical technology to shield hypersonic vehicles from the intense heat experienced when flying at more than five times the speed of sound.

The contract was from the AFRL Materials and Manufacturing Directorate for a project called ďmultipurpose thermal protection systems for hypersonics.Ē

Anyway, AFRL has recently extended the contract (Award ID FA865021C5253) to add an additional $8M for "Multipurpose Thermal Protection Systems for Hypersonics Add Work"

Online FutureSpaceTourist

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 33251
  • UK
    • Plan 28
  • Liked: 58539
  • Likes Given: 26194
Re: Starship heat shield
« Reply #3287 on: 12/29/2022 04:46 am »
twitter.com/drchriscombs/status/1608207918310252544

Quote
Notice how w each iteration we see a higher % of tiles that are a custom fit to their unique location. Was probably inevitable

I know they wanted to simplify things but Iíve got a feeling the tile layout is basically gonna look like the shuttle when itís done #starship #SpaceX

https://twitter.com/drphiltill/status/1608236249386717184

Quote
Having worked on and around Space shuttle tiles, I can tell you thereís a thing known as ďstep and gapĒ (important for laminar flow and heat transfer), and the tiles in this picture donít yet demonstrate mastery of that topic (to say the least).

twitter.com/stuck4ger/status/1608280328187133952

Quote
Isnít Starshipsís reentry AOA around 60 deg (2X the Shuttle)? Are step inconsistencies as important at those extreme alphas? I was told Soviet fighters had much worse surface tolerances than American fighters because they didnít see the need to over design for the mission.

https://twitter.com/drphiltill/status/1608291129451069440

Quote
I donít know. I agree that their requirements are likely a lot different.

Offline meekGee

  • Senior Member
  • *****
  • Posts: 12849
  • N. California
  • Liked: 12119
  • Likes Given: 1337
Re: Starship heat shield
« Reply #3288 on: 12/29/2022 07:06 pm »
I thought that because SS is not a rigid structure, gaps are inevitable and not as controlled as they were in Shuttle.

There was something a year or so ago about part of the mitigation being the hexagonal shape, since it discouraged plasma flow in the gaps.  Also the Stainless skin of course.
ABCD - Always Be Counting Down

Online InterestedEngineer

  • Full Member
  • ****
  • Posts: 949
  • Seattle
  • Liked: 768
  • Likes Given: 1144
Re: Starship heat shield
« Reply #3289 on: 12/30/2022 05:27 pm »
An interesting paper on gaps in heat shields, via numerical simulation:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117012

Some interesting quotes:

Quote
Heat flux ratio in the gap decreases as Mach number increases, because the boundary layer tends to be thinner and air flowing into the gap decreases as Mach number increases.

The faster you go the more gap you can have (by a few mm)

Quote
The heat flux ratio is basically U-shaped distribution along the surface of a gap.

The axis being vertical: heat flux ratio to a standard flat surface, and horizontal: the length along the gap. Note at higher mach numbers there's a bigger spike but in the gap the heat decreases. Post gap there's a heat increase but it's not a square function.

Note his is for flat surfaces.  The complexities of flows around the flaperons is probably why they fill in the gaps in those areas.

Quote
Thus, setting chamfer in the windward can reduce the gap effect coefficient, which is a valid method for reducing the gap local aerodynamic heating environment.

I can't recall, are the edges of the tiles chamfered?

TL;DR - the gaps in the main body are fine.  Any refinement is due to updated CFD modeling, which SpaceX is a world class expert at.

Online eriblo

  • Full Member
  • ****
  • Posts: 1058
  • Sweden
  • Liked: 1297
  • Likes Given: 227
Re: Starship heat shield
« Reply #3290 on: 12/30/2022 06:38 pm »
My understanding is that the Orbiters were as smooth as possible to delay the boundary layer tripping from laminar flow to turbulent as long as possible (in both time and space).

This can decrease the peak temperature and total heat load for the flat surfaces downstream of the stagnation points along the nose and leading edges.

Starship currently has the same TPS design on the whole surface (the exception being small radii and compound curvatures). This suggest that it is overkill with regard to the increased heat transport from surface irregularities.

The Starship architecture as a whole is of course not quite as sensitive to a (initially?) slightly less mass optimized heat shield...

Online InterestedEngineer

  • Full Member
  • ****
  • Posts: 949
  • Seattle
  • Liked: 768
  • Likes Given: 1144
Re: Starship heat shield
« Reply #3291 on: 01/13/2023 08:03 am »
Quote
https://twitter.com/ringwatchers/status/1613691353472405504

Before/after pics of black paint being added.

Black paint can change stainless steel's Stefan Boltzman emission constant from 0.35 to 0.98 or so, so 2.5x more watts emitted per unit area.

Which adds margin for any area that is exposed to moderate amounts of reentry heat.
« Last Edit: 01/13/2023 08:04 am by InterestedEngineer »

Offline Oersted

  • Member
  • Senior Member
  • *****
  • Posts: 2566
  • Liked: 3512
  • Likes Given: 2407
Re: Starship heat shield
« Reply #3292 on: 01/14/2023 10:47 am »
Open question: would each and every tile carry an RFID chip (or similar) to help identify problems during the upcoming orbital mission? Could be helpful to see if/when and where tiles come off during all phases of the flight.

Online eriblo

  • Full Member
  • ****
  • Posts: 1058
  • Sweden
  • Liked: 1297
  • Likes Given: 227
Re: Starship heat shield
« Reply #3293 on: 01/15/2023 01:54 pm »
Open question: would each and every tile carry an RFID chip (or similar) to help identify problems during the upcoming orbital mission? Could be helpful to see if/when and where tiles come off during all phases of the flight.
There might be RFID tags that can survive the temperatures involved but I think it would require quite a bit of work. It would also be tricky to read them as they are mounted on a curved metal surface.

Other options would be a wire/fiber optic mesh behind the insulation as well as cameras inside the tanks or mounted on the flaps.

I think the only TPS related sensors we have seen are the handfull of likely temperature sensors mounted on the ventral side of the nose cone/payload bay.

One thing I could see on the first flight is a simple free flying or tethered 360 camera deployed from the aft skirt after SECO. There has been talk of something like that on Polaris Dawn and it should require a minimum of effort.

Online Slothman

  • Full Member
  • ****
  • Posts: 431
  • Liked: 455
  • Likes Given: 26
Re: Starship heat shield
« Reply #3294 on: 01/15/2023 06:05 pm »
Open question: would each and every tile carry an RFID chip (or similar) to help identify problems during the upcoming orbital mission? Could be helpful to see if/when and where tiles come off during all phases of the flight.
There might be RFID tags that can survive the temperatures involved but I think it would require quite a bit of work. It would also be tricky to read them as they are mounted on a curved metal surface.

Other options would be a wire/fiber optic mesh behind the insulation as well as cameras inside the tanks or mounted on the flaps.

I think the only TPS related sensors we have seen are the handfull of likely temperature sensors mounted on the ventral side of the nose cone/payload bay.

One thing I could see on the first flight is a simple free flying or tethered 360 camera deployed from the aft skirt after SECO. There has been talk of something like that on Polaris Dawn and it should require a minimum of effort.

I mean.. it would be significantly difficult to read RFID chips in flight, which is apparently where the question was going, talking about detecting *when* tiles fall off, meaning having a constant connection to each tile. That's just insane. You would need a reader probably under the tiles or inside the barrel every couple inches.

At most I could imagine a 1-wire detection circuit per tile but even that is way overkill for a reusable starship.

Offline meekGee

  • Senior Member
  • *****
  • Posts: 12849
  • N. California
  • Liked: 12119
  • Likes Given: 1337
Re: Starship heat shield
« Reply #3295 on: 01/15/2023 06:29 pm »
Open question: would each and every tile carry an RFID chip (or similar) to help identify problems during the upcoming orbital mission? Could be helpful to see if/when and where tiles come off during all phases of the flight.
I think much can be learned using IR cameras looking at the inside of the skin.

To elaborate:

Because of the aspect ratio of the skin, temperature variations on the outside will imprint nicely on the inside.  Not exactly 1:1 but with some modeling you can reconstruct exactly what's happening on the outside, including tile temperature, plasma flow between tiles, etc.

You will know what happened at each location, and when, and the recording continues even as tiles fail, all the way until the vehicle fails.

And you'll even have a record of that, which will be so awesome. (With stainless, it might actually glow before failing)
« Last Edit: 01/15/2023 06:54 pm by meekGee »
ABCD - Always Be Counting Down

Offline DanClemmensen

  • Senior Member
  • *****
  • Posts: 3077
  • Earth (currently)
  • Liked: 2395
  • Likes Given: 928
Re: Starship heat shield
« Reply #3296 on: 01/15/2023 06:49 pm »
Open question: would each and every tile carry an RFID chip (or similar) to help identify problems during the upcoming orbital mission? Could be helpful to see if/when and where tiles come off during all phases of the flight.
I do not know of an RF system that could operate "over the air" near a big stainless steel tank. There might conceivably be a way to use some sort of skin effect to transmit along the surface of the tank. A network of thousands of these would be a challenge. the bigger question is "why?". Addition of the tranceiver and sensors to the tile would change its physical characteristics, probably making it more delicate and less insulating, not to mention being a manufacturing nightmare.

Offline BT52

  • Full Member
  • *
  • Posts: 117
  • Liked: 43
  • Likes Given: 171
Re: Starship heat shield
« Reply #3297 on: 01/15/2023 07:09 pm »
I think temp probes (or cameras  inside tank  as from AA video WHERE Musk mentioned it as possibility) and raw TELESCOPE video analysis are enough  of indication. And same goes for both ascent and descend ofc. 

If u lose tile at ascent and descent both are viable test situations worth to test it. And its effects i.e. hot spots will be seen indirectly via temperature at ship tank skin anyway. At ascent u will not seen immediately necessary  but at orbit they  will definitely took its look how many tiles they lost IMO

Offline OTV Booster

  • Senior Member
  • *****
  • Posts: 4456
  • Terra is my nation; currently Kansas
  • Liked: 3053
  • Likes Given: 4997
Re: Starship heat shield
« Reply #3298 on: 01/15/2023 08:45 pm »
Open question: would each and every tile carry an RFID chip (or similar) to help identify problems during the upcoming orbital mission? Could be helpful to see if/when and where tiles come off during all phases of the flight.
There might be RFID tags that can survive the temperatures involved but I think it would require quite a bit of work. It would also be tricky to read them as they are mounted on a curved metal surface.

Other options would be a wire/fiber optic mesh behind the insulation as well as cameras inside the tanks or mounted on the flaps.

I think the only TPS related sensors we have seen are the handfull of likely temperature sensors mounted on the ventral side of the nose cone/payload bay.

One thing I could see on the first flight is a simple free flying or tethered 360 camera deployed from the aft skirt after SECO. There has been talk of something like that on Polaris Dawn and it should require a minimum of effort.

I mean.. it would be significantly difficult to read RFID chips in flight, which is apparently where the question was going, talking about detecting *when* tiles fall off, meaning having a constant connection to each tile. That's just insane. You would need a reader probably under the tiles or inside the barrel every couple inches.

At most I could imagine a 1-wire detection circuit per tile but even that is way overkill for a reusable starship.
I've brought this up in the past and gotten no traction. Acustic sensing. It probably wouldn't work when the main engines are firing but otherwise a network of mic's and some serious DSP's behind them could conceivably localize to individual tiles and with a good signal library, pin down what happened.


We've all heard how that hull rings when beaten by a hammer. It transmits sounds quite well. Every material has a characteristic acoustic signature. I doubt there is anything on the starship that would sound like a cracking tile except... a cracking tile. There is a lot of other noise but that's what DSP's are for. They pull small signal out of big noise.


Cracking is only one failure mode and even it has subcategories. How fine a discrimination is possible is an open question but at a gross level of tagging failures, I think it would work.


Any sonar operators out there? :D
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

Offline Oersted

  • Member
  • Senior Member
  • *****
  • Posts: 2566
  • Liked: 3512
  • Likes Given: 2407
Re: Starship heat shield
« Reply #3299 on: 01/16/2023 06:11 am »
Tile detachment detection with that kind of granularity would primarily be for the initial test flights. Hopefully wouldn't be needed on a mature launch system.

Tags:
 

Advertisement NovaTech
Advertisement SkyTale Software GmbH
Advertisement Northrop Grumman
Advertisement
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0