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Saw this discussed on the NASASpaceflight forum:

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Don't know if you know about it but this site has some useful articles 

https://www.nasaspaceflight.com/2022/09/starship-next-phase-of-testing/

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As previously reported, Ship 26 and Ship 27 may be undergoing a radical change in plans, omitting thermal protection system (TPS) tiles and not installing aerodynamic flaps. So far, this seems to be holding true with parts of Ship 26 seen now bare of tiles and on stand-by at Starbase’s ring yard for stacking.

Ship 27 parts are also proceeding similarly to Ship 26 parts. In some cases, there seems to be a strange mix-match of parts for these vehicles.

 

https://www.nasaspaceflight.com/2022/08/booster-7-additional-tests/

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While all of this is happening, workers have been seen doing unusual work on future Starship vehicles and more concretely on Ship 26.

Workers were seen removing Thermal Protection System (TPS) tiles and blankets from Ship 26’s nosecone, while some of its barrel sections, which were supposed to receive the installation pins for the TPS tiles, are already staged outside in the ring yard ready for stacking.

While there has not been any official reason provided, some indications point to SpaceX trying to fast-track Ship 26 and Ship 27 builds by not installing TPS tiles or even flaps in order to quickly deliver Starlink v2 satellites into orbit, which the company may need in order to accelerate deployment once Starship proves itself worthy of going into orbit

 

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https://forum.nasaspaceflight.com/index.php?topic=50748.msg2409134#msg2409134

 With every test firing of the Starship some tiles pop off. There is some speculation Starship may be launched on the first test flight without the tiles, obviously in an expendable mode.

 Here’s a picture of the pins that hold on the tiles:

ZlBSm.jpg

 It seems you could get stronger type pins than that. For example you could use spring-loaded wing nuts:

01310701_3.jpg

 Apparently SpaceX does not want to glue the tiles on like what happened with the shuttle because it takes too much maintenance time for replacement and refurbishment.

 But with the wing nuts you can adjust the strength to be removable but strong enough to hold on during flight.

 By the way, according to the discussion in that thread on NasaSpaceflight.com SpaceX is looking to improve on the tiles they are using.  I advise considering mathematician and engineers GW Johnson’s ultra lightweight, reusable TPS material:

 

 

   Robert Clark

Edited by Exoscientist
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18 minutes ago, kerbiloid said:

Heated magnets stop being magnets.

Also - and I think this is probably less likely here - it’s relatively easy to slide a magnet along a surface than it is to pull it off that surface.

Having the heat shield buckle because the tiles start sliding and riding up over each other at max Q is probably a suboptimal outcome.

 

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7 hours ago, kerbiloid said:

Heated magnets stop being magnets.

They also don't especially like being chilled. Ferrous magnets stop being magnets at cryogenic temperature, and Neodymium loses 30% of its strength. Samarium Cobalt are better, losing only 10%.

I know this because of a stint as a production engineer where the design engineers gave me some large and awkwardly-shaped steel components to freeze-fit using liquid nitrogen without allowing me to machine any lifting features into them.

Had some "fun" designing cryogenic lifting magnets.

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54 minutes ago, Exoscientist said:

This NASAspaceflight video also speculates SpaceX might be considering an expendable Starship version, with no heat shield or flaps:

We know there are versions that will lack EDL capability. Maybe they will test some. They still need to dispose of them, though, so we'll have to see. I would expect that as long as they have to deorbit them, they might as well at least test as many elements of EDL as possible.

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7 hours ago, Shpaget said:

Isn't 301 stainless non magnetic?

301 is so called austenitic steel. It means it has face centered cubic lattice, in which iron is not ferromagnetic. It is ferromagnetic only if it is in body centered cubic lattice (ferritic iron). However, there may be small ferritic areas due to for example lattice defects and sometimes austenitic steels may have mild ferromagnetic properties. It is far too weak effect to hold anything but you can barely feel it with strong magnet.  I also  think that such defects are not wanted in rocket hull because they affect structural and chemical properties too.

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3 hours ago, Hannu2 said:

301 is so called austenitic steel. It means it has face centered cubic lattice, in which iron is not ferromagnetic. It is ferromagnetic only if it is in body centered cubic lattice (ferritic iron). However, there may be small ferritic areas due to for example lattice defects and sometimes austenitic steels may have mild ferromagnetic properties. It is far too weak effect to hold anything but you can barely feel it with strong magnet.  I also  think that such defects are not wanted in rocket hull because they affect structural and chemical properties too.

This is getting a little beyond the scope of the topic, but since we're on a materials science tangent, I may as well add one more detail. The statement that 301 (or, more generally, 300 series austenitic stainless steels) are nonmagnetic is only true for the material that is in the as-cast or annealed form. Cold working can cause austenite to transition to martensite, which is magnetic.

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11 hours ago, Silavite said:

This is getting a little beyond the scope of the topic, but since we're on a materials science tangent, I may as well add one more detail. The statement that 301 (or, more generally, 300 series austenitic stainless steels) are nonmagnetic is only true for the material that is in the as-cast or annealed form. Cold working can cause austenite to transition to martensite, which is magnetic.

 Thanks for that. Surprising scientifically that the same material can be magnetic or non-magnetic depending on how you work it.

  Robert Clark

 

  

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