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Posted (edited)

even if they have to glue them on like with the shuttle, i think just having a smaller set of standard tiles will be an improvement.  no shuttle had been lost due to tile issues, carbon-carbon panels dont count, that's a different material doing the same job.

what ever happened to large ceramic coated hulls?  skylon was wanting to do something like that. or at least large ceramic panels instead of tiles. seems its easier to replace a small number of large panels than a large number of small tiles. if you can solve the thermal stress cracking issue.

Edited by Nuke
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16 hours ago, Nuke said:

even if they have to glue them on like with the shuttle, i think just having a smaller set of standard tiles will be an improvement.  no shuttle had been lost due to tile issues, carbon-carbon panels dont count, that's a different material doing the same job.

what ever happened to large ceramic coated hulls?  skylon was wanting to do something like that. or at least large ceramic panels instead of tiles. seems its easier to replace a small number of large panels than a large number of small tiles. if you can solve the thermal stress cracking issue.

Apparently they are replacing most of the glue on tiles around some of  the ring weld lines with the hard mounted type.  I wonder if the lost tiles were all glued ones.  This could end up being less of a deal if that was the case.  Hard mount 'em all

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On 6/1/2024 at 7:30 PM, Nuke said:

even if they have to glue them on like with the shuttle, i think just having a smaller set of standard tiles will be an improvement.  no shuttle had been lost due to tile issues, carbon-carbon panels dont count, that's a different material doing the same job.

what ever happened to large ceramic coated hulls?  skylon was wanting to do something like that. or at least large ceramic panels instead of tiles. seems its easier to replace a small number of large panels than a large number of small tiles. if you can solve the thermal stress cracking issue.

They were originally going to make Starship entirely out of carbon fiber and use a ceramic/composite PICA-X on it, but they ditched that because of carbon fiber cost as well as impact to reusability.

Going for larger panels is all well and good until you lose one due to a manufacturing defect and expose a gigantic chunk of your hull that immediately burns through. The small size of the tiles on Starship is supposed to help reduce the impact of a single lost tile so that it's not an instant LOV event. The small size of the tiles also means they can be evenly tessellated despite being entirely flat, which dramatically reduces manufacturing costs. One of the reasons Shuttle was so expensive was that every one of the 24,000+ tiles was a different size and shape and could only be glued on in a single spot, while the vast majority of the 18,000 tiles on Starship are identical.

I've always mused about the possibility of using a spray-on ablative paint. All things being equal, it shouldn't be TERRIBLY hard to build a covered robotic rig that sprays the entire windward surface of Starship with an epoxy/amine insulative-ablative coating like E-400. It would be part of the standard procedure between flights, just like refilling: spray it with a solvent to remove soot and residue, then spray it with the epoxy, then spray it with whatever is needed to fix the epoxy. If they can build a rocket-grabbing mechazilla they can build a giant spraypainting rig. There are certainly some probable environmental impact issues there but the materials science should be up to the task. Maybe the materials science is there, but the weight penalty would be too great?

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32 minutes ago, sevenperforce said:

They were originally going to make Starship entirely out of carbon fiber and use a ceramic/composite PICA-X on it, but they ditched that because of carbon fiber cost as well as impact to reusability.

Going for larger panels is all well and good until you lose one due to a manufacturing defect and expose a gigantic chunk of your hull that immediately burns through. The small size of the tiles on Starship is supposed to help reduce the impact of a single lost tile so that it's not an instant LOV event. The small size of the tiles also means they can be evenly tessellated despite being entirely flat, which dramatically reduces manufacturing costs. One of the reasons Shuttle was so expensive was that every one of the 24,000+ tiles was a different size and shape and could only be glued on in a single spot, while the vast majority of the 18,000 tiles on Starship are identical.

I've always mused about the possibility of using a spray-on ablative paint. All things being equal, it shouldn't be TERRIBLY hard to build a covered robotic rig that sprays the entire windward surface of Starship with an epoxy/amine insulative-ablative coating like E-400. It would be part of the standard procedure between flights, just like refilling: spray it with a solvent to remove soot and residue, then spray it with the epoxy, then spray it with whatever is needed to fix the epoxy. If they can build a rocket-grabbing mechazilla they can build a giant spraypainting rig. There are certainly some probable environmental impact issues there but the materials science should be up to the task. Maybe the materials science is there, but the weight penalty would be too great?

 

Whenever something is not done with engineering there is usually a legitmate reason.

Elon and his crew are trying to do whatever works but without spending more than they have to.

So the reason is somewhere in there. They for the most part only design stuff on starship as they do because they have to (the really pointy nose being an exception since Elon was inspired by the Sasha Baron Cohen The Dictator movie).

 

I hope the reason is not money, because that means they could do your idea but just choose not to. It would be more reasonable if your idea was a bad one due to the TWR not being able to match the weight of the anti-heat covering.

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1 hour ago, sevenperforce said:

They were originally going to make Starship entirely out of carbon fiber and use a ceramic/composite PICA-X on it, but they ditched that because of carbon fiber cost as well as impact to reusability.

Going for larger panels is all well and good until you lose one due to a manufacturing defect and expose a gigantic chunk of your hull that immediately burns through. The small size of the tiles on Starship is supposed to help reduce the impact of a single lost tile so that it's not an instant LOV event. The small size of the tiles also means they can be evenly tessellated despite being entirely flat, which dramatically reduces manufacturing costs. One of the reasons Shuttle was so expensive was that every one of the 24,000+ tiles was a different size and shape and could only be glued on in a single spot, while the vast majority of the 18,000 tiles on Starship are identical.

I've always mused about the possibility of using a spray-on ablative paint. All things being equal, it shouldn't be TERRIBLY hard to build a covered robotic rig that sprays the entire windward surface of Starship with an epoxy/amine insulative-ablative coating like E-400. It would be part of the standard procedure between flights, just like refilling: spray it with a solvent to remove soot and residue, then spray it with the epoxy, then spray it with whatever is needed to fix the epoxy. If they can build a rocket-grabbing mechazilla they can build a giant spraypainting rig. There are certainly some probable environmental impact issues there but the materials science should be up to the task. Maybe the materials science is there, but the weight penalty would be too great?

Larger panels that had a hexagonal breakaway pattern in it such that it would come off in smaller pieces might be possible.  Basically what they have now but they'd be connected and applied in sheets, like kitchen ceramic tile on a mesh?  Idk, just pondering out loud

I like the spray on concept, but I keep thinking some kind of aerogel

 

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2 hours ago, Spacescifi said:

I hope the reason is not money, because that means they could do your idea but just choose not to.

Money is the whole point. If money was no object then you could just spam disposable rockets. The whole point of reusable rockets is to save money.

2 hours ago, Spacescifi said:

It would be more reasonable if your idea was a bad one due to the TWR not being able to match the weight of the anti-heat covering.

TWR would never be a problem. The problem would be mass ratio.

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Money is VERY OFTEN the reason why engineering even exists.

One of my favorite lines is from a race car engineering book by Carrol Smith. He defines an engineer as "someone who can do for a dime what any fool can do for a dollar".

Anybody can build a bridge with infinite materials, but it takes an engineer to make it elegantly simple (and therefore cheap).

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3 hours ago, darthgently said:

Basically what they have now but they'd be connected and applied in sheets, like kitchen ceramic tile on a mesh?

I do like this idea. Although I imagine more small steel bands where tiles are attached to and then larger patches are mounted on starship by fixing this bands instead of tiles. So it acts as intermediate structure while a mesh would only be assistant structure for mounting and they somehow would still need to attach each tile.

Yet the "do not fail on single tile loss" remark is still unsolved by this. Basically I can only think to split each tile in 2 layers to overcome this. Then offset one layer, which probably makes attachment easier as well.

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I have a new supposition - supposition, I stress - on what caused the blockage in IFT-3's Booster: oxygen. Specifically slush oxygen, a mixture of liquid and solid O2.

SpaceX already uses subcooled propellants in Falcon 9, and slush oxygen and other subcooled propellants were investigated by NASA in the 70s, finding significant mass savings on their then-current dream of SSTO. Near-boiling-point LOX (183.3°C) was 1140 kg/m3, and LOX subcooled to triple point (-218°C) at 1 bar was 1310kg/m3: Cryogenic Propellant Densification Study (1978)

Interestingly, triple-point/slush methane is mentioned, though only to say, "We don't have the data, we'll have to make some assumptions and treat it like slush hydrogen or RP-1".

Maybe in IFT-3 they were testing out lower temps of oxygen, some transient event like slosh during boostback caused pressure to drop and a clot of oxygen slush developed at just the wrong time. If you've ever tried to wash snow or ice down the drain you'll know that it can cause temporary blockages, and while the impellers inside the rocket engines should chew up any oxygen snowflakes, the tanks being nearly empty combined with the blockage and slosh caused a fatal hiccup.

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Posted (edited)
2 hours ago, mikegarrison said:

Money is VERY OFTEN the reason why engineering even exists.

One of my favorite lines is from a race car engineering book by Carrol Smith. He defines an engineer as "someone who can do for a dime what any fool can do for a dollar".

Anybody can build a bridge with infinite materials, but it takes an engineer to make it elegantly simple (and therefore cheap).

Heh, I've often heard that line formulated as "Any fool can build a brige that stands solidly in place. It takes an engineer to make a bridge that barely stands in place."

Or alternately, "Engineering is physics with a budget" (extension of "Physics is mathematics with a reality check").

Edited by Codraroll
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51 minutes ago, PakledHostage said:

CSI Space has an interesting new video about the interstage ring, and the plan to jettison it on IFT-4:

 

Very interesting watch! I didn't realize the interstage wasn't actually welded into the boosters. Animations are also spectacular.

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9 minutes ago, GuessingEveryDay said:

Well that begs the question, when are they doing night launches? The plume would look glorious.

I assume you are not being serious here, but no one does night launches unless they have to. There is simply no valid reason to add the possible complications of darkness to the risks of the launch.

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SpaceX is ready to launch starship no earlier than tomorrow. here is  the place to discuss about it's planned trajectory and goals, it's newest hardwar and software developpement compared to last time, and hopefully, the results of it's fourth flight.

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We already have a SpaceX thread and I imagine most posts related to this flight will be posted there as has been done for all the other test flights and all things SpaceX.  Just don't want you to be all by yourself here wondering where everyone is

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