Quote from: Keldor on 04/26/2020 09:07 amQuote from: DreamyPickle on 04/26/2020 07:35 amHaving a large number of intricate tile shapes might not be a problem by itself as long as they don't require a manual repairs. Unlike on the Shuttle there is no chance of getting hit by debris during launch.For tiling a rounded cone they could do it using the same slightly warped hexagon at each height point.But they might eventually go for unique shapes of varying thickness anyway in order to optimize mass.It's actually mathematically impossible to tile a rounded cone with any sort of uniform warped hexagon. If you try it, you'll find that it works alright at the beginning, but as the surface continues curving, your hexagons will become more and more distorted until you're forced to add pentagons to the mix. This is a direct consequence of the Euler Identity.There's just no way to avoid requiring a large number of different tile shapes when trying to tile a surface with non-zero curvature. (A cylinder has, mathematically speaking, zero curvature, just to be clear on this. Not so for a rounded cone)Mathematically you're correct.But engineers like to cheat 1 type of tile in 2 forms, whole and cut in half.PS: I'd like to emphasize that only 200deg of SS needs to be tiled.
Quote from: DreamyPickle on 04/26/2020 07:35 amHaving a large number of intricate tile shapes might not be a problem by itself as long as they don't require a manual repairs. Unlike on the Shuttle there is no chance of getting hit by debris during launch.For tiling a rounded cone they could do it using the same slightly warped hexagon at each height point.But they might eventually go for unique shapes of varying thickness anyway in order to optimize mass.It's actually mathematically impossible to tile a rounded cone with any sort of uniform warped hexagon. If you try it, you'll find that it works alright at the beginning, but as the surface continues curving, your hexagons will become more and more distorted until you're forced to add pentagons to the mix. This is a direct consequence of the Euler Identity.There's just no way to avoid requiring a large number of different tile shapes when trying to tile a surface with non-zero curvature. (A cylinder has, mathematically speaking, zero curvature, just to be clear on this. Not so for a rounded cone)
Having a large number of intricate tile shapes might not be a problem by itself as long as they don't require a manual repairs. Unlike on the Shuttle there is no chance of getting hit by debris during launch.For tiling a rounded cone they could do it using the same slightly warped hexagon at each height point.But they might eventually go for unique shapes of varying thickness anyway in order to optimize mass.
No straight path for hot gas to accelerate through the gaps
Quote from: DusanC on 04/26/2020 09:31 amQuote from: Keldor on 04/26/2020 09:07 amQuote from: DreamyPickle on 04/26/2020 07:35 amHaving a large number of intricate tile shapes might not be a problem by itself as long as they don't require a manual repairs. Unlike on the Shuttle there is no chance of getting hit by debris during launch.For tiling a rounded cone they could do it using the same slightly warped hexagon at each height point.But they might eventually go for unique shapes of varying thickness anyway in order to optimize mass.It's actually mathematically impossible to tile a rounded cone with any sort of uniform warped hexagon. If you try it, you'll find that it works alright at the beginning, but as the surface continues curving, your hexagons will become more and more distorted until you're forced to add pentagons to the mix. This is a direct consequence of the Euler Identity.There's just no way to avoid requiring a large number of different tile shapes when trying to tile a surface with non-zero curvature. (A cylinder has, mathematically speaking, zero curvature, just to be clear on this. Not so for a rounded cone)Mathematically you're correct.But engineers like to cheat 1 type of tile in 2 forms, whole and cut in half.PS: I'd like to emphasize that only 200deg of SS needs to be tiled.Long straight lines like that are problematic.In the words of Elon when asked why hexagons:QuoteNo straight path for hot gas to accelerate through the gapshttps://twitter.com/elonmusk/status/1107379727302451200
Seems there has been some discussion concerning the nature and geometry of the tiles to be used on Starship.https://forum.nasaspaceflight.com/index.php?topic=50620.msg2073268#msg2073268Moving this to a separate thread as requestedHere's my take on what the tile layout might be. I know that everyone is trying to minimise the number of tiles, but I think there is a trade off and if they need to have a few dozen tile types to make a reliable and uniform surface then so be it. In my design the tiles get narrower as you move towards the apex. At some point depending on the degree of curvature relative to the size of the tiles it might also be necessary to decrease their height as well.
Quote from: Slarty1080 on 04/26/2020 01:01 pmSeems there has been some discussion concerning the nature and geometry of the tiles to be used on Starship.https://forum.nasaspaceflight.com/index.php?topic=50620.msg2073268#msg2073268Moving this to a separate thread as requestedHere's my take on what the tile layout might be. I know that everyone is trying to minimise the number of tiles, but I think there is a trade off and if they need to have a few dozen tile types to make a reliable and uniform surface then so be it. In my design the tiles get narrower as you move towards the apex. At some point depending on the degree of curvature relative to the size of the tiles it might also be necessary to decrease their height as well.[bolding mine]As long as there are multiples of each shape, whole rows for example, I wholeheartedly agree with this. We have to remember that there will be hundreds of these ships, so having different shapes, as long as they aren’t “one offs” shouldn’t be a problem. This applies to initial construction and repairs (both on Earth or Mars). Biggest issue with the shuttle was that almost every single tile was slightly different.
I have a questions based on excellent BCG's photos https://forum.nasaspaceflight.com/index.php?topic=48895.msg2072270#msg2072270There are indications that some tiles on SS SN4 are made by coating bent sheet metal. There are even some areas where there is small surface damage to the coating. Is there any other explanation?
Will the tiles be flat and approximate the 9 meter curved shape of SS? Or will the tiles themselves have That 9M curve made into them?The forward end of the nose will need to be curved, probably in 2 dimensions the closer to the nose.Once flying the heat shield could easily be a multi year improvement project. Edit: There will be plenty of specialty pieces around and on the control surfaces as well.
Quote from: wannamoonbase on 04/26/2020 02:36 pmWill the tiles be flat and approximate the 9 meter curved shape of SS? ... flat is probably significantly cheaper, and good enough to do the job.
Will the tiles be flat and approximate the 9 meter curved shape of SS? ...
Quote from: DusanC on 04/26/2020 01:38 pmI have a questions based on excellent BCG's photos https://forum.nasaspaceflight.com/index.php?topic=48895.msg2072270#msg2072270There are indications that some tiles on SS SN4 are made by coating bent sheet metal. There are even some areas where there is small surface damage to the coating. Is there any other explanation?- The tiles look similar to how the Shuttle tiles were made. Molded white rigid insulation (AETB or similar) with a hard outer coating for protection and control of emissivity. I don't know how you would mechanically attach such a tile since the rigid insulation have very little strength. Perhaps structural inserts molded into the insulation.- Rigid insulation is easily milled to any shape, then the coating is applied. John
Quote from: livingjw on 04/26/2020 04:13 pmQuote from: DusanC on 04/26/2020 01:38 pmI have a questions based on excellent BCG's photos https://forum.nasaspaceflight.com/index.php?topic=48895.msg2072270#msg2072270There are indications that some tiles on SS SN4 are made by coating bent sheet metal. There are even some areas where there is small surface damage to the coating. Is there any other explanation?- The tiles look similar to how the Shuttle tiles were made. Molded white rigid insulation (AETB or similar) with a hard outer coating for protection and control of emissivity. I don't know how you would mechanically attach such a tile since the rigid insulation have very little strength. Perhaps structural inserts molded into the insulation.- Rigid insulation is easily milled to any shape, then the coating is applied. Johnso maybe many different types of tiles will be viable and for repairing (on mars for example) they'll just have blanks and cut it with a small cnc milling machine (it shouldn't be heavy at all)
Yes, the tiles are ~-05% fiber and binder and 95% void.
Quote from: livingjw on 04/26/2020 05:32 pmYes, the tiles are ~-05% fiber and binder and 95% void. For attachment points, maybe when they are casting/molding the tiles, they insert a fiber matrix that terminates in one or more attachment points?Or they could glue an attachment plate onto the bottom of each tile, but that could add a lot of weight.