Author Topic: Starship heat shield  (Read 1281764 times)

Offline IanThePineapple

Re: Starship heat shield
« Reply #960 on: 03/08/2021 03:36 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.

Offline steveleach

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Re: Starship heat shield
« Reply #961 on: 03/08/2021 03:40 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?

Offline zeekakboos

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Re: Starship heat shield
« Reply #962 on: 03/08/2021 03:44 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?


I think they mean more coverage of the prototypes, not a greater number of tiles for a full heatshield.

Offline steveleach

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Re: Starship heat shield
« Reply #963 on: 03/08/2021 03:50 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?


I think they mean more coverage of the prototypes, not a greater number of tiles for a full heatshield.
Yes, that's what I assumed they meant.

But why have more tiles on the prototypes? What does the larger patch tell you that the smaller one doesn't?

Offline eriblo

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Re: Starship heat shield
« Reply #964 on: 03/08/2021 03:57 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?


I think they mean more coverage of the prototypes, not a greater number of tiles for a full heatshield.
Yes, that's what I assumed they meant.

But why have more tiles on the prototypes? What does the larger patch tell you that the smaller one doesn't?
You get more practice installing them and better statistics on the installation processes and mechanical/thermal performance.

Offline zeekakboos

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Re: Starship heat shield
« Reply #965 on: 03/08/2021 04:01 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?


I think they mean more coverage of the prototypes, not a greater number of tiles for a full heatshield.
Yes, that's what I assumed they meant.

But why have more tiles on the prototypes? What does the larger patch tell you that the smaller one doesn't?
You get more practice installing them and better statistics on the installation processes and mechanical/thermal performance.
And maybe as prototypes are built and SX sees the likelihood of each crashing shrink they're willing to install more tiles.
« Last Edit: 03/08/2021 04:02 pm by zeekakboos »

Offline steveleach

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Re: Starship heat shield
« Reply #966 on: 03/08/2021 04:35 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?


I think they mean more coverage of the prototypes, not a greater number of tiles for a full heatshield.
Yes, that's what I assumed they meant.

But why have more tiles on the prototypes? What does the larger patch tell you that the smaller one doesn't?
You get more practice installing them and better statistics on the installation processes and mechanical/thermal performance.
And maybe as prototypes are built and SX sees the likelihood of each crashing shrink they're willing to install more tiles.
But if the justification is practice and data gathering, why not just put on the full set?

Offline Stan-1967

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Re: Starship heat shield
« Reply #967 on: 03/08/2021 04:38 pm »
I have also been wondering if they will get better or worse landing profiles with more of the heat shield installed as, the additional mass of the heatshield moves the center of mass of Starship ( in the Z-Y plane ) away from the geometric centerline of the vehicle.  I had a hard time finding reliable guestimates of the heatshield mass, but a 15t heatshield would make a 662kN*m moment arm. 

If the landing is to be on two engines, it seems like you want to prioritize moving the CoM towards the thrust vector of the primary landing engines.  That would minimize the off axis gimbal angle needed for the asymetric CoM.  Would it even be possible to move the centroid three center raptors slightly towards the asymetic CG to have better control in nominal & off nominal landings?

edited X-Y plane to Z-Y plane.  My understanding is that x-axis is along the length of the ship
« Last Edit: 03/08/2021 06:46 pm by Stan-1967 »

Offline zeekakboos

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Re: Starship heat shield
« Reply #968 on: 03/08/2021 04:41 pm »
SN11 has 360 tiles on the body, unsure if any on the flaps. SN10 had 246. Interesting to watch it grow over time.
I'm confused - what advantage would there be in having the greater number of tiles?


I think they mean more coverage of the prototypes, not a greater number of tiles for a full heatshield.
Yes, that's what I assumed they meant.

But why have more tiles on the prototypes? What does the larger patch tell you that the smaller one doesn't?
You get more practice installing them and better statistics on the installation processes and mechanical/thermal performance.
And maybe as prototypes are built and SX sees the likelihood of each crashing shrink they're willing to install more tiles.
But if the justification is practice and data gathering, why not just put on the full set?
Cost? and of course they don't really need the full heatshield for actually protecting the vehicle until probably >SN15 so might as well work your way up

Offline steveleach

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Re: Starship heat shield
« Reply #969 on: 03/08/2021 04:55 pm »
Yes, that's what I assumed they meant.

But why have more tiles on the prototypes? What does the larger patch tell you that the smaller one doesn't?
You get more practice installing them and better statistics on the installation processes and mechanical/thermal performance.
And maybe as prototypes are built and SX sees the likelihood of each crashing shrink they're willing to install more tiles.
But if the justification is practice and data gathering, why not just put on the full set?
Cost? and of course they don't really need the full heatshield for actually protecting the vehicle until probably >SN15 so might as well work your way up
Yep, OK. So that means they need to use the smallest area they can.

There are drivers to have more, and drivers to have less.

I'm trying to figure out if anyone has a theory on why SN11 has more than SN10.

I'll throw in a theory of my own, just to move the discussion on: they have a fixed "budget" for tiles on each prototype, and they are getting better at installing them so the same budget lets them install more tiles.

Offline InterestedEngineer

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Re: Starship heat shield
« Reply #970 on: 03/08/2021 05:01 pm »
I have also been wondering if they will get better or worse landing profiles with more of the heat shield installed as, the additional mass of the heatshield moves the center of mass of Starship ( in the X-Y plane ) away from the geometric centerline of the vehicle.  I had a hard time finding reliable guestimates of the heatshield mass, but a 15t heatshield would make a 662kN*m moment arm. 

If the landing is to be on two engines, it seems like you want to prioritize moving the CoM towards the thrust vector of the primary landing engines.  That would minimize the off axis gimbal angle needed for the asymetric CoM.  Would it even be possible to move the centroid three center raptors slightly towards the asymetic CG to have better control in nominal & off nominal landings?

there's likely going to be a service tunnel on the leeward side where  you currently see exposed wires, which will counter balance some of the heatshield mass.

also the 15t isn't 4.5 meters out, it's a half circle so COM is  0.42 * 4.5 = 1.9 meters out.  so it's really 280kN*m.

The service tunnel needs to only mass  280kn*m/4.5 / 9.8 = 6.4 tons to counter this.  Probably won't weigh that much unless they put the battery on the lweward side.

COM for a half circle:  ( )

Much discussion beyond this needs to go to the Engineering thread.  I"m pasting this thread there.

Offline Cheapchips

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Re: Starship heat shield
« Reply #971 on: 03/08/2021 06:26 pm »
I'm trying to figure out if anyone has a theory on why SN11 has more than SN10.

I'll throw in a theory of my own, just to move the discussion on: they have a fixed "budget" for tiles on each prototype, and they are getting better at installing them so the same budget lets them install more tiles.

They might still be trying out slightly different tile manufacturing / ramping up manufacturing.  Wasn't there something about that  in a job ad?

Didn't SN10 also have a significant area of unused attachment studs? They might not have had enough tiles to populate it. Or it was just the stud robot going nuts.  :)

Offline steveleach

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Re: Starship heat shield
« Reply #972 on: 03/08/2021 06:33 pm »
I'm trying to figure out if anyone has a theory on why SN11 has more than SN10.

I'll throw in a theory of my own, just to move the discussion on: they have a fixed "budget" for tiles on each prototype, and they are getting better at installing them so the same budget lets them install more tiles.

They might still be trying out slightly different tile manufacturing / ramping up manufacturing.  Wasn't there something about that  in a job ad?

Didn't SN10 also have a significant area of unused attachment studs? They might not have had enough tiles to populate it. Or it was just the stud robot going nuts.  :)
Yep, though you could argue that manufacturing capacity is just how they determine the "tile budget" for each SN, so it's basically a variant.

Any other ideas?

Offline Genial Precis

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Re: Starship heat shield
« Reply #973 on: 03/08/2021 07:26 pm »
My completely uninformed guess is that the heat shield-attaching processes are being worked out, but it's not a high priority because you want to adjust things in response to high-fidelity real data about how it performs in use, which they only get so much of in these tests where there's no heat to shield. There's no incentive to spend a lot of time optimizing things for an objective you haven't tested yet.

I'm not at all sure either why the amount of heat shield would increase but not so quickly.

Offline Jimmy_C

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Re: Starship heat shield
« Reply #974 on: 03/08/2021 07:46 pm »
I'm not at all sure either why the amount of heat shield would increase but not so quickly.

While a part waits for it's turn to be moved to the next stage of the assembly line, the heat shield fairy robot practices on it. The method for applying heat shields just gets quicker each time. At least that's my best guess. They might be trying to figure out the error rate.

Offline awests

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Re: Starship heat shield
« Reply #975 on: 03/08/2021 08:10 pm »
Some crazy good close-ups of the tiles:

https://twitter.com/cooper_hime/status/1369029998934392833?s=21

Credit: Cooper Hime


Sent from my iPhone using Tapatalk

Offline Lars-J

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Re: Starship heat shield
« Reply #976 on: 03/08/2021 09:21 pm »
Another good shot, with humans for scale:

https://twitter.com/Cooper_Hime/status/1368961299976192003
« Last Edit: 03/08/2021 09:23 pm by Lars-J »

Offline steveleach

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Re: Starship heat shield
« Reply #977 on: 03/08/2021 09:33 pm »
Why do they use half-tiles on the top and bottom, but not the left and right?

Offline Slarty1080

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Re: Starship heat shield
« Reply #978 on: 03/08/2021 09:35 pm »
Why do they use half-tiles on the top and bottom, but not the left and right?
They will have to use half tiles at the bottom at least, but need not used half tiles at the sides (although they might)
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline steveleach

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Re: Starship heat shield
« Reply #979 on: 03/08/2021 09:48 pm »
Why do they use half-tiles on the top and bottom, but not the left and right?
They will have to use half tiles at the bottom at least, but need not used half tiles at the sides (although they might)
Can you imagine Elon letting them build it (the "final" version) without straight sides? He wants his spaceships to look good.

 

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