I wish you guys would make more of these narrated videos. They are really, really good. For those who have moved on from the intense live following it'd be awesome to have some more narrated news/information/etc.
@@amdullahaa No reason to bring mythological claims into this. Science and engineering are evidenced based, there is just no need for magical thinking.
Heyy NSF, I just want you to know these weekly videos are about as good as Everyday Astronaut documentaries. They're just that good. Please keep em coming.
@@NASASpaceflight Tim is reprehensible, as he's made his content far too much about him and his persona relative to what he's covering. NSF is vastly superior in that regard, except when "Das" is involved. Outside of that, the sheer volume of coverage that NSF provides blows Tim out of the water.
@@MicahTischler . Hmm. That's a bit harsh. .. "Reprehensible is a strong word describing behavior that should evoke severe criticism." . (Merriam-Webster)
Tile loss from Space Shuttle Orbiter in 1979--those were temporary polyurethane tiles installed for the flight on the back of the 747 from Edwards AFB to KSC. The loss of Columbia during EDL in Feb 2003 was not caused by tile loss or damage. The carbon-carbon composite leading edge of the left wing was damaged by thermal insulating foam that became detached from the External Tank and caused that disaster. The tiles were not involved in either the Challenger disaster or the loss of Columbia. The tiles performed perfectly on the 133 successful Shuttle Orbiter EDLs (100% reliability). Starship has that flexible ceramic fiber mat between the backside of the tile and the stainless steel hull. It could be something like Kaowool 3000 that would provide added protection to the hull up to 2900F (1593C). If the number of hex tiles on Starship is really 18,000 and there are three fastening posts per tile, that's 54,000 posts, each of which is resistance welded to the stainless steel hull by robotic welders. I would expect at least a few weld failures to occur randomly among those tiles. The probability of a given tile would have two or three defective welds on its three posts is vanishingly small. Side note: I worked on development and testing of the Space Shuttle tiles during the conceptual design period (1969-70). Later, in 1995-96 I did similar work for the X-33 thermal protection system.
With your experience you seem confident that the tile system will work well in the long run. quick question could you guesstimate what weight the TPS would be in total? how heavy would one of those tiles roughly be? also do they use something to fill the gaps between the tiles?
@@bolgert911 If the density of those hex tiles is 9 lb/ft^3 (145 kg/m^3, same as the tiles on the bottom of the Space Shuttle Orbiter) and the tile thickness is 3" (0.0762m), the surface density of the tiles is 11 kg/m^2. The area of the windward side of Ship (the second stage of Starship) is 793 m^2. So the mass of that heat shield is 8.8t (metric tons).
Good points. It sounds like they are assuming that only two attachments (or perhaps one) are needed to anchor the tiles. This seems hard to assure in the design/testing phase. With the vibration and turbulent flow around flaps etc. it's easy to image tiles becoming dislodged even if only one fastening post fails. Can you get local outward pressumes on tiles? Say due to high pressure under the tiles and turbulence on the outside?
@@marksinclair701 If the flexible ceramic fiber mat that now is placed between the tile backside and the stainless steel hull absorbs water in the humid air at Boca Chica or at the Cape, then it's possible that you could get high pressure under the tiles during the EDL if the temperature of that mat exceeds the boiling point of water. The tiles on the Shuttle Orbiters were re-waterproofed between each launch to prevent high pressure inside the tile from causing cracks. Also the weight of absorbed water can be several tons. Each pound of water absorbed by the tiles reduces the payload to orbit by one pound. I don't know how Elon waterproofs the tiles on Starship.
@@rays2506 Fascinating. And this is occuring during EDL? Wondering if the the water would boil off (sublimate?) in vacuum during launch or in orbit. I haven't seen any sign of waterproofing measures between tiles on Starship. Seems like a bigger potential problem for Starship than on the Shuttle - won't the cold tanks condense ice behind the tiles?
This is the biggest issue. Getting the tolerances on the snap on system correct and the quality level high enough to work 100% of the time is very tough.
@@jonbong98 It is my understanding that right now they have to destroy a tile to remove it. A metal frame that contains one way clips is imbedded in the ceramic material the tiles are made of. When installed the posts welded to the ship snap into the clips in the frame. To remove the tile they have to cut a hole through the tile to release the clip because it is buried inside the tile. There are many possible things that could cause the tiles to pop off. If the barbed top of the post is a little to small or the clip a little to big or the ceramic coating on the frame is filling some of the post hole the post does not properly lock in. The other possible failure mode is the barbed tip of the attachment post breaking off under stress due to stress cracks from forming or maybe the clip edges making a stress rising notch in the barbed post. What complicates this is the requirement of the attachment system must accommodate expansion and contraction due to tile heating and be robust enough to withstand the vibrations experienced during launch.
Your commentary is very professional and the content of the script is concise and on point. You should do more of these discussing different aspects of the Spacex show.
Adiabatic compression : Have you ever used a hand pump to blow up a bicycle tyre? Have both the tyre and pump at room temperature. Now pump them up until fully inflated, and keep a reasonable pace. You will notice both the pump and the tyre have risen in temperature. This is NOT due to friction, that plays only the smallest part, it's called adiabatic compression. As the air/gas is compressed together the average energy of that volume goes up, the molecules are buping into each other more often, to reach equilibrium again, it has to radiate that extra energy as heat. Refrigerators and freezers use a related trick. They compresses a gas so it heats up, they use a radiator to get rid of that heat, then decompress the gas in another radiator that is inside the fridge. That compressed and cooled gas, now needs to regain that lost heat, so is takes it from inside the fridge. Same thing and a neat trrick. Now when a spacecraft slams into the atmosphere faster than the air can get out of the way(faster than the speed of sound), it is compresses the air in front of it. The spacecraft is using the air to slow down, as that saves a lot of fuel, otherwise it could have slowed enough to void the issue all together That air heats up a LOT, a ludicrous amount in fact! It end up radiating enough heat to destroy a spacecraft that does not have adequate protection. Friction only plays a small part compared to the hinges of hell level of heat generated by adiabatic compression as a spacecraft comes screaming home, so to speak. It's like the heat generated by the bicycle pump compression of the air, just dialled up to godmode level.🥴 If it did not work like that, your fridge and freezer would not be able to chill food at all, the universe is weird like that at times😊🤗
While I can picture Starship successfully getting into orbit on its first try, I think it'll take two or three tries to bring it down in one piece. There are just so many "don't know until we try" elements with the tiles as they currently are.
Tiles are so last century. A better approach would be a thermal blanket witch is deployed on re-entry and it envelops the ship then disposed of by rotating the ship, or once the speed is reduced it could become like a parachute to help with slowing it down further.
Good Summary Video! Even Elon has alluded to his concerns that the tiles may not be up to the task. Myself, I've worked with refractory lined furnaces where the attachments are often the failure point. I am very concerned that the TPS as it looks today is a likely failure point during re-entry due to them falling off during launch and the stress of re-entry. I am confident SpaceX will figure out a solution, but I will be surprised if the TPS isn't involved in a re-entry failure during the first few orbital flights. Hopefully, Starship makes it to that point!
Agree, at the moment they seem to "pop off" as easily as they "pop on" which is the problem, could be rectified with some sort of bolt fixing but they maybe deemed too slow a process for the prototypes. It's a pity the active cooling system wasn't pursued further as long-term it may have been a better solution.
I'm just going to say that yes, I do realize that this is all testing, and that especially early on the shuttle also had issues with it's tiles coming off. However, with the shuttle it was (as far as I'm aware) never the primary black tiles coming off, but the white ones on the tail on the top leeward side of the reentry. It seems concerning to me that they still keep coming off during static pressure testing and not even under the full dynamic load.
Quite a few black tiles either cracked or chipped. One fell off and it was only the fact that underneath the tile was a steel antenna element that prevented disaster. Most likely they are coming off because the fragile silica material is tearing away from the mounting hardware - its a hard problem. Also, when you lose a tile, the extra aerodynamic load on its neighbours could lead to a zipper effect.
Yes I am concerned that it could be because starship is so long, with such a flexible straight frame that it could be that is the reason why these tiles are coming off. The shuttle was definitely old and over engineered, but I had a very rigid frame and didn’t go through these Cryotests with cooling or expansion of its frame as much under heat and/or friction. we know obviously starship mustn’t be able to flex too much as that will damage its internal hardware, but inevitably there will still be some with such a long tube frame like this, and those little bits of movement along a body like this where eventually it will add up to a central point, and the effects of the Cryo-tests will inevitably cause tiles to come off. At least that’s what I’m speculating, so this is making me incredibly worried. I really don’t know how SpaceX is going to be able to get around this as I’m really scared this could be some sort of intrinsically inherent problem with all spacecraft that are designed to be able to re-enter the atmosphere. Perhaps it’s one we will never be able to get around. Not until we can actually create a metal body that can survive on its own without a heat shield attached to the rest of the hull, or actually create genuine real energy shields that can hold back the friction heat. For now, perhaps spacex should try using different shaped tiles in the end for the main body like squares instead.
Good video, thanks. One thing: when you say the underlayer is felt, viewers might get the impression that it's the most common type, which is made of wool. For added clarity, It's actually a ceramic blanket, sometimes called a ceramic felt. It can withstand temperatures up to about 1,250 C (2,200 F) without damage, and doesn't melt until 1,760 C (3,200 F). Pretty tough stuff.
Depends on the type but some can even go higher in temps than that. Fiberfrax 2600 for example. It is designed to go to 2600°F ( 1430°C ) without damage.
Agreed. I think heat shields in general are the next technology that will lead to a new era of space travel. We're getting pretty good with engines, so we got the "up" part uh... down? Now we have to get the down part sorted out.
One way that the TPS could be tested on a larger scale would be to place it underneath a static fire test. The design of a rocket engine is very similar to that of a supersonic wind tunnel. The exhaust from the raptors is both hypersonic and hot.
Most realistic simulation is to simply mount the tiles to the wall of the booster during a static fire. Sound pressure isn't the only reason they can fail. During re-entry there is high dynamic loading, high shear stress, flexing of the vehicle (its not being stiffened by internal pressure at this point) and turbulent flow.
The issue is not whether the tiles can protect against the heat of re-entry, there is not much doubt that they can. The issue is how many tiles will be lost at launch. Too many lost and it will be toast.
They have to fly it to get all conditions. Or spend months in building different test chambers that still won't cover every aspect of flight. They already know the tiles can with stand the heat. Now they need to freeze one side and push starship through the atmosphere and see wut happens.
totally agree with the comments. But remember materials science and design has changed greatly since the space shuttle. But there is only one way to see.
Some comments: - Tiles can fail, crack or fall off during the stress of re-entry. High shear loads, flexing of the body of the vehicle (which won't be pressurised, unlike launch) and turbulence are all in play. - The mechanism of failure appears to be in the interface between the tile material and the metal embedded in the tile that forms part of the one-way clip. One suspects this interface is too rigid and thus the fragile silica material is tearing from the mounting hardware. Would be nice if SpaceX were more transparent about this. - The time the Space Shuttle survived a lost tile on the hot side, we were extremely lucky because the tile was sitting over a steel antenna element, which protected the vehicle. - The felt blanket isn't designed for direct contact with plasma. It will survive some leakage, but it will decompose/ablate if a tile falls off. Worse if a group of tiles falls off. - There is a progressive failure mode where if one tile falls off, it creates more shear stress on the tiles next to it, leading to a zipper effect. - If the stainless steel is exposed, it probably won't melt, but it can soften, deform and other more sensitive components may be exposed to high temperatures and lead to unpredictable failure. SpaceX might be able to remedy this with a more substantial internal reinforcement (the metal embedded within the tile), but this will add weight. I was quite keen on the original transpirational cooling and there are other methods including a "hot skin" (Rocket Labs is considering this for the feet of its Neutron) and there are hybrid methods involving some active cooling. Those who think Starship will be operational in a year or two don't understand how hard the engineering is.
@@ronwoodward716 That isn't what happens. SpaceX starts with liquids cooled well below their boiling point. Once the engines shut off, the remaining liquid acts to condense the gas (transferring energy out of the gas and into the liquid). Net result is reduced pressure. It can go below atmospheric. There's always an equilibrium pressure, but its not enough to stiffen the tank. Even the header tanks will act to cool the space around them. Plus the cargo bay will be unpressurised.
@@saumyacow4435 The fuel tanks on the Star Ship are balloon style tanks. The walls of the tanks are very thin for their size and weight. That thin structure cannot maintain the desired shape under load without it being pressurized. This is done to save weight. The tanks must be pressurized at all times except during construction. They even pressurize them during transport to the test and launch stands. Once loaded with propellant the fuel and oxidizer constantly boils off to maintain the low temperature. The gas created by this boil off must regularly be vented to prevent the tanks from going over pressure and exploding. Because of this SpaceX has eliminated the cold gas maneuvering thrusters and instead use the boil off gas for maneuvering. The tanks are never below atmospheric pressure. Especially in space because the external pressure is essentially zero. Any internal pressure will act to stiffen the structure of the spacecraft. As for the cargo hold it may or may not be pressurized depending on the cargo. If they ship is carrying people it will be pressurized. For the early launches probably not. If it is not pressurized the inside will be covered with stiffening stringers to carry the loads for launch and reentry. The inside has many structural elements now that are needed to spread the loads from lifting points, flap attachments, engine mounts, fueling ports, valves etc.
@@ronwoodward716 Ok for starters its not technically a balloon tank. It is structurally stable sitting empty, or sitting full of propellant but without pressure, at least until it is accelerated. Real balloon tanks have to be pressurised before they can be filled. But leaving that aside, you're not differentiating between the booster and the upper stage of Starship. The booster has no insulation and the heat transferred from the surrounding air is significant and will pressurise the contents. Hence you need vents to control the pressure. The upper stage of Starship is a different thing entirely. For a start, once it is in space, there's no convective heat transfer because there's no atmosphere. Secondly, its heavily insulated which limits heat gain even from exposure to the sun. And in the course of a suborbital flight you're not spending enough time exposed to the sun to compensate for the fact that the propellant is super cooled. It will in fact cause the gas to recondense into the liquid - at least for some time as the liquid soaks up heat. Whilst the liquid remains cooled well below its boiling point, the equilibrium gas pressure will be well below 1 bar. You need several bar. Again, if you want it to be stiffened by pressure, you have to have a heater of some sort. And you have to keep generating gas because its not in equilibrium. That gas will still want to return to liquid phase because the liquid is still well below boiling point. And also you need that heat source to generate gas pressure before descent - since you're not going to be using the main engines until near landing. You can add all the stringers and bracing you like, but the structure will flex during descent. That's a guarantee. Even with pressurisation, the loads during descent are high. The loads exerted on the flaps have to be distributed around the shell. Unless you're going to the extent of having an extremely rigid internal 3D isogrid, its still going to flex. Airplanes do this and they have lots of stiffeners. It doesn't matter a lot because they're not trying to hang on to fragile silica bricks. Oh and one other thing. Starship will have a large unpressurised volume (for cargo). That requires special attention structurally because it cannot be stiffened by pressure. And its right in the zone where forces from the forward flaps will be transmitted. Now going back to the original issue. The tiles are clearly failing because there's an interface between the tile material (fragile/brittle silica) and the metal that forms the tile side of the clip mechanism. That has to be fixed. As for the overall structural soundness of Starship. Well, that remains to be seen. You can engineer your way out of it, but the real question is about what usable payload do you end up with? Every tonne of extra structural mass is a tonne less payload. The temptation is unfortunately to push the limits. Not a good idea for prototyping. Its better to over-engineer then figure out where the mass isn't needed later. Its a pity that Elon walked away from carbon fibre. Maybe he'll go back to it.
I work at a specialty silica plant! We don’t make aerospace material (I think), but we do make food grade and pharmaceutical grade silica quite often. Very cool process, and the testing is rather involved.
All the current starships are prototypes. I’m sure that some failures are expected. Failures will lead to further testing and redesign. Eventually, they’ll get it right. So don’t lose faith. Expect failures.
@@javaman4584 Looking at early development of the Space Shuttle they had a very hard time with the tiles, maybe even more so then Starship right now, and considering that Starship is an easier design then the Space Shuttle and NASA got that to work. Well, they'll probably get it
@@rushpuppy2 You seriously think Elon himself is the best qualified person for this? I can promise you a bachelor in art and physics does not make him an expert. There are much more capable men/women out there to try solving this
Materials-wise the heat shields seem like they're ready, design-wise I feel like they're not at all mature and still have a very long way to go. In the long term I do not think that having 18,000 tiles is practical and I continue to expect them to introduce some sort of external lattice structure to host larger and more reinforced tiles in a more sturdy vibration-resistant manner, which incidentally could also make them easier to service. I think the first orbital ship will 100% burn up on re-entry, they'll learn a ton about what a re-design needs to target, and they'll sacrifice a few more tons on a more robust and dependable heat management system on later prototypes. I think that in 18 months we'll all feel confident about starship's heat management capabilities because they'll have been addressed through failure.
The larger they are, the more fragile they are mechanically. The current setup is three spring loaded clips that hold the tile. I would be surprised if they directly hold the tile material. Rather they should have embedded metal in the tile (its poured/cast) and so its metal to metal contact. However, what's probably happening is that the tile material is tearing away from the embedded metal mounting points. And this is a tricky compromise because you need compliance (spring) to compensate for the tile growing as it heats (It will also tend to grow more on the outer surface than the inner one, causing it to bow outwards as well as expand into the gaps. That puts more stress on those (hopefully) compliant mounting clips. Bigger the tile, the bigger these issues are. You can make the embedded metal larger and more complex to avoid tearing. But you still have the issue of differential expansion between the materials. What I'm saying here is that there's a reason why they ended up dinner plate size. And of course everything you do to compensate for these problems will add weight.
I think SpaceX are going to encounter much more problems with the tiles than the shuttle did. Once Nasa had worked out how to fix the tiles in place on shuttle, the system generally worked very well - with the exception of being hit by debris of course, but on the whole they rarely fell of or became damaged without something striking them. The shuttle had a fairly stiff aluminium frame, thus the tiles always had a very sturdy and non flexing surface to fix to. This is where I think Starship will have problems, the surface they attach to is not so rigid, just pressuring the ship tends to flex the stainless steel sheets that the ship is made from. Any shock waves the vehicle encounters - from it's own engines for example, will likely travel through the liquid fuel inside the tank, that will be enough to flex the steel. For example think back to the Concorde crash in Paris, that was caused by bits of tyre hitting the wing fuel tank, not hard enough for the tyre to penetrate the tank, but hard enough to send a shock wave through the fuel itself. The shock wave was strong enough to cause the fuel to punch a hole through the tank from the inside out. Of course that tank was just aluminium, Starships tanks a much much stronger, and any shock wave Starship is likely to encounter during normal operation will be nowhere near strong enough to cause the fuel to punch a hole in a tank, but it may well be enough to cause sections of the tank to flex. Which is why I feel Starship will encounter problems - especially seeing that the tiles are only clipped into place. I suspect one reason they are clipping the tiles in place is to try and prevent tile breakage due to the tank flexing. When we see tiles flying off during tests it is hard to tell if they are falling off simply because the shock wave through the tank is enough to unclip them, or whether it is actually breaking the tiles. Will be interesting to see how a full heat shield will perform with a full stack launch.
The Shuttle had at least one tile on the hot side that detached and would have resulted in tragedy if not for luck - under the tile was a steel antenna element that protected the aluminium. You're quite right about the flexing of the underlying metal. Starship is basically a big soda can. Very high diameter to wall thickness ratio. Its going to want to flex, particularly on descent where the tanks will be mainly empty and the main tanks unpressurised. Its subjected to high torques from those flaps. Plus there is likely turbulence as the plasma stream shears off the edge of the hot surface and also around the flaps. Turbulence and shear stresses on the tiles isn't good. But it may also prompt a dynamic response from the hull. The problem with the clips is that on the tile side there would be a piece of metal embedded into the tile so that there is a metal to metal connection. But then there is an interface between the fragile tile material and the embedded metal - quite likely the tile is tearing at this interface. Then you run into a conflict between enlarging the embedded metal (to have more grip on the tile) and introducing more stress from thermal differentials.
@@saumyacow4435 The tanks will still have pressure in them even when landing. The question is will it be enough to prevent severe flexing. That is what the test flights will have to show. SpaceX can always add more stringers to stiffen the hull if needed.
@@gravelydon7072 Nothing to generate pressure. The residual liquid is likely to cause remaining gas to recondense. You need running engines (or a deliberate heater) to generate pressure. There will be flexing. Its a big tin can being torqued by the loads applied by the flaps and subject to the pressure variations caused by turbulence. It may even demonstratw feedback between the structure flexing and the external flow.
@@saumyacow4435 They do not need engines running to create pressure. Just the warming of the fluids to a gas will raise the pressure. Not all the fuel will be out of the tanks before landing. Empty tanks that still had pressure while in space will see an increase in pressure when reentry occurs. It will have to vent pressure when returning.
I expect the unexpected with the higest probability of RUD during reentry. This is where the try fail learn try fail learn rapid prototyping works. You can only do so much in the lab.
"How do you think Starship will fare on its orbital test flight?" -Much better than anyone but Elon could imagine. Starship will most likely be destroyed its maidan flight in one way or another but lots to learn in the process! "Will everything go perfect?" -No way, way too many things that can go wrong. "Will there be a heatshield issue?" -Based on the tests done so far, I would imagine so. Long way to go in their development but Elon and his team will figure it out.
Much to learn - provided you can instrument and document what went wrong. And that's a little hard on ascent since you don't have eyes on those tiles. And its even harder on descent because even if you instrument, there's no live data stream.
I would say based on observing how many tiles crack and/or fall off at 0 knots, that the forces during ascent to include vibrations and supersonic/hypersonic airflows will likely severely damage the tile system. The ship may make it to orbit, but the tile system will likely be in very bad shape.
@@aDifferentJT The aerodynamics on ascent will create serious pressure, turbulence and acoustical vibrations, steering inputs and winds will also induce some flexure in the airframe. Agreed the 33 raptors spitting out hell on earth at the launch pad will also be horrendous.
Great video. Suggestion for next video - mention the mechanism of failure when those tiles fell off. Shock overpressure waves from the engines hitting the structure most likely would not occur when the vehicle is 70m+ away from the engines that will be firing on the Pad. And a totally different mechanism of failure compared with re-entry where hypersonic regime thermal and aero loads dominate.
@nasaspaceflight … “Tile problems” DID NOT “lead to the loss of a shuttle crew”. Foam shed from the external tank during launch struck and damaged the reinforced carbon-carbon leading edge of Columbia’s left wing. The RCC was part of the orbiters’ overall thermal protection system … and the damage ultimately did lead to the loss of vehicle during reentry … but this incident had nothing to do with the ceramic tiles (a separate component of the TPS). Tile loss and maintenance was definitely an ongoing issue that significantly slowed flight cadence and potentially risked the safety of vehicle and crew on at least one occasion; but “tile issues” never resulted in such a loss during the life of the program.
I also believe I’ve seen elsewhere that the photo you showed of an orbiter missing a multitude of tiles after a 747 ride was merely the result of having shipped the orbiter with tile installation incomplete. Not tiles just randomly falling off during transport.
I am guessing the felt under the tiles is ceramic fibre blanket and the mesh net holding that on probably Nichrome wire? This would be typically used to line the inside of pottery kilns up to 1300 degrees. So it looks like the tiles are also helping to hold the blanket in place against the steel , like a duvet without squashing it flat, also providing thermal insulation behind the gaps between the tiles.
I feel like the tiles go against the whole idea of rapid reusability, they're just not reliable enough. I'd like to see them work on something a bit more advanced than tiles, maybe some sort of composite shell.
The original concept (and part of the justification for stainless steel) was transpirational cooling. I'm working on a concept that involves porous carbon foam (much tougher than silica) and active cooling. Basically, liquid methane is fed into the carbon foam and comes out as hot methane gas. Methane is good in that its heat capacity rises with temperature so its a great coolant.
@Hafgren. Starship is and will continue to be in it's development phase for some time to come. I'm sure that the TPS is high on the list to be refined, but it is hard to know what needs to be improved without conducting a suborbital test. Hopefully that test is forthcoming pending FAA approval.
@@ericlotze7724 You are right on one point and that is you are speaking from an armchair perspective. Me, I don't have any armchairs so I'm speaking from my dining room chair perspective.
Really enjoy the channel and the high quality of work you do. If I can make one friendly suggestion: run a mouth de-click on the voiceover. That will eliminate the audible mouth noise. Highly recommend RX9 by Izotope.
I expect the first "orbital" attempt to fail on re-entry. In my opinion re-entry is the single most difficult task for any space ship. Making the TPS survive hundreds (?) of launches wow!
I believe that there will be some glitches early on, that is why you do rigorous unmanned testing. If anyone can eventually solve problems it is SpaceX!
I think reentry is no problem for these tiles, they were designed to support the force in that direction that basically pushes them in to the bracket they are mounted to. The problem in my opinion is the lateral movement on the pad at launch, they seem to be susceptible to that lateral motion way more and that’s the part of the mission to look at very carefully.
Analysis of the Thermal Protection System was exceptionally difficult for the shuttle, you really had to make sure you had the right cover sheet on your TPS report.
I will be both astonished and ecstatic if it even makes it to orbit. Let alone survive re-entry. No booster has performed a test flight. I would imagine all those raptors firing up is going to generate quite a shock wave and a lot of noise. I'm glad finally to start hearing someone talk about the tiles issue, it's been bugging me for ages. I am sure SpaceX can and will fix any issues but checking thousands of tiles between flights is potentially a big problem for rapid reusability. Especially if you want it certified for human flight. I can't imagine NASA allowing astronauts on board if even a single tile is missing.
And don’t forget that unlike the Shuttle that was built from Aluminum which melts starting at 900 deg F. The Starship is made from Stainless steel which retains much of its strength and structure at temp over 2500 deg F.
@@Penfold101 At no point did the Shuttle reach that temp. The boundary air is a different story but it is not in direct contact with the tiles or hull. The black tiles on the Shuttle were rated for only 2300°F. Just the thermal blankets can be higher rated than that.
@@Penfold101 , at 3000 deg F aluminum is a fully pourable liquid, and in the presence of Oxygen will combust. At its melt point of 900 deg F it is beginning to sag. Stainless Steel at 900 deg F is still at full strength, at 2500 deg F it maintains 95% or more of its strength, at 3000 deg F it still maintains some strength. Which would you rather have during re entry? I’d much rather be in the Stainless Steel space ship! The biggest flaw in the Shuttles design was the metal used in its construction.
@@Penfold101 Because you need a rigid surface to shield the blankets and keep the heat as much as possible off the Stainless Steel. If you used thick enough stainless, you would not need any TPS at all. But the weight of it would be more than the TPS would be. And that would mean a loss in payload. Ten tons of TPS would hold up better than ten tons of stainless. And with the current design of the TPS, they might also be able after a flight to re-coat the tiles with the putty like compound for another go if there is excessive ablation.
The tiles are being lovingly crafted as a masterpiece work of art. We need fast much faster, maybe one-piece tps. Change out in under an hour. It's really just an overgrown fairing half made of high temp material.
Surving re-entry is one thing, but the question is whether the vehicle is left in a quickly re-usable state. It took a while for SpaceX to learn how to weld glorified grain silos that didn't rip apart when pressurized and getting to a stable state involved automated welding equipment. Not sure how well artisanal welding of a patch of new steel over an area damaged by loss of tiles would work next time the tanks are filled. Once iterative testing/development restarts this year, SpaceX will learn from the failure and adapt. Note: gap between tiles likely more about steel compressing when loaded with cryogenics and then expanding during re-entry than the tiles expanding on their own.
Man i am obsessed with SpaceX and Starship, i cannot wait for the day we get blessed to see the first flight. Yet The closer it gets and the more i see of the Catch/Launch tower. I get more and more nervous. The Starship itself to me isn't my main source of concern. It is the Booster. Much much larger and heavier then SS. I see such a microscopic room for error on the Landing/catch attempt. That booster is about Tons Fueled and about 150 Tons at complete dry mass and about 170-200 At landing. If it comes down to that tower with even a 5 or 6 foot off target or a higher velocity by even a small fraction could lead to an obliteration of 2 years of work in a flash. During the first Catch attempt the booster will NOT have the same room for error the Falcons had in there evolution or even Starship with its Tests. Both Falcon and ProtoStarship had something that They had Very miniscule to no Surrounding Equipment with the Cost/Time to build ratio that the Booster will have around it on its landing. (IF) the booster were to impact the tower directly, or miss the tower all together i believe would lead to an absolute destruction( or damaged to point of rebuild) of the tower and surrounding equipment. With the Tank farm also so close would be another large worry in the case of a landing failure. I understand, you cannot learn if you don't try, but i never thought of it from this point of view that this thing will have to be almost laser accurate in all aspects for this to end up without utter catastrophe. It will be Success or Rebuilding and designing for the next 1 to 2 years. Thank you NASASpaceflight for all you do for this.
An isolated tile loss should not be catastrophic, but my concern is if a cascade of tiles will peel off. The belly is going to be subject to high external pressure. With a belly tile lost, the high pressure can spread _under the tiles_ to areas with a lower external pressure, thus subjecting those tiles to strain. [ The thermal blankets will limit flow rate and each tile seam will tend to equalize the pressure difference. But is that enough? ]
Its called the zipper effect and yes its a serious problem. You have to have connectors that are tough enough to just not fail - and that's hard because the tile material itself is very fragile. However you attach it, there's always an interface where the tile can crush or tear. Its not just high dynamic pressure, its also flexing of the steel (its a tin can basically) and its turbulence.
I think Starship (stage 2) will and should be seen as a disposable stage for many many flights. All focus has to be on getting the booster back given the sheer number of engines it has. + I think they'll come up with some legs for the booster before attempting catches--sacrificing a bit of payload for not destroying your launch site seems reasonable!
This does not have to be an either or issue during this early prototyping of starship. The goal is to bring both back. After all both booster and ship are undergoing constant development. Space X isn't considering landing legs at this point. Perhaps later. "The best part is no part". EM
Thanks for the great video, Ian! With regard to your statement that "failure of the heatshield during the first re-entry attempt would not be a setback for Spoacex (since Spacex would have another starship ready to try again)" is debatable. If there's an inherent design problem with the TPS (attachment, fragility, etc) that's a big big problem for Starship. Sending up another Starship with the same TPS design is not going to fix things...
Many are bias regarding tile fragility after close observation of the shuttle activities over the years. We can't even be sure this is the final method of tile attachment since these are still early Starship prototypes. Given what SpaceX has done with F9 booster reentry and dragon reentry one would expect they have a good idea of what it takes to make a sound TPS.
As Ian explains one of the big issues is testing the entire TPS, as a unit, on the ground. The fundamental design of Starship is fundamentally superior to that of Shuttle with regard to surviving reentry for many reasons. Basically where relatively small damage to the Shuttle TPS could result in the loss of the crew, that is simply extremely unlikely with Starship. Starship will survive reentry. What is at risk is whether Starship will survive in shape to be relaunched with minimal investment. To maximize the productivity of Starship it is necessary to maximize payload. Every kg reduction in the dry mass of Starship translates to 1 kg of additional payload. So SpaceX wants to have a TPS implementation which minimizes the mass of the TPS. Designing a TPS in which 100% of the tiles survived launch is desirable, but would result in a heavier implementation. This is why I proposed that one of the Starships from the "Rocket Garden" which has an almost complete set of tiles be placed underneath a 33 engine static fire, the only force on Earth which could possibly test an entire Starship as a unit. This would reveal what will happen when a Starship re-enters with missing tiles. Remember it is not IF a Starship will re-enter with missing tiles, it is WHEN it will re-enter with missing tiles. "Perfect is the enemy of good."
There has got to be a better solution than these damn tiles! Tile loss has been a severe problem since the early days of the shuttle and apparently haven't gotten any better in the last 40 years. I'm surprised SpaceX, which is known for their "thinking out of the box" solutions went with such an old and problematic method.
You are making an assumption that simply because Space X is also using tile system that it using an old problematic system. The TPS for Starship is very different from the shuttle in having most of the tiles having the same size as well a different attachment system. Second Starship has a steel hull which is much more resistant to heat then the alternatives. Finally, the effectiveness of the Starship TPS can only be truly tested in an orbital test which is imminent. I should also mention that your comment offers only criticism of the current TPS of starship, but no suggestions for an alternative.
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They *did* think outside the box: originally, Starship was going to use transpiration cooling (in other words: "sweat") using pores in the hull which deposit a thin film of liquid methane onto the skin. We don't know too much about why they abandoned this idea and went back to tiles, but we can assume that the reason is some variation of *because it doesn't work and tiles do*.
A couple notes - the nonwoven white fabric underneath the tiles isn't felt, that would just be...well.. absurd. It's a type of meltblown/meltspun rockwool or mineral wool, like fiberglass but doesn't melt until the temperature is 800C higher. Also, it wasn't the silica based tiles that doomed Columbia, it was the graphitic reinforced carbon-carbon panel on the leading edge of the wing, used where the highest temperatures were incurred.
This and the fact that the engines are highly stressed and complex - another source of inspection/maintenance delays. Have you checked out Rocket Labs's Neutron, for a master class in how to do reusability?
I do enjoy the narrative method of explaining the process of developing the challenges that are being dealt with in making a successful and economical space craft. Although it does look like an oversized corn dog to me,. I often thought it would be sweet to just build an oversized vat of the slurry to dip the space ship into it and then stick the hull in an oven to cure the heat shield so it all stayed on and then finish it off at Boca Cica with tanks and fins and pipes and engines. Super simple and fast and sweet~ haha.
Fiberfrax makes a putty for doing just that sort of thing. They also make topcoats that can go to 2800°F. The black tiles on the bottom of the Shuttle were only 2300°F rated.
Random tile question: Could those be used instead of the problematic martite under launch stands? They are designed to withstand extreme heat and wind velocities, so they should stand up under the Raptor 2 exhausts, right?
I expect some heat tiles to fall off, but the vehicle to be entirely undamaged and to successfully complete its mission 🤙🏼 Hopefully that means landing at LEAST the starship back in one piece, able to do another sub-orbital flight
In Starship’s defense, the stainless steel body can take a magnitude more heat than the aluminum body of the Space Shuttle. And the uniform body will make dissipating built up heat easier. Heat tiles falling off even in patches isn’t much of a concern. It would take large patches of them falling off to really worry me.
Is it possible to make inflatable heat shield for Starship and/or a ballute? Maybe not for when it comes down with any meaningfull payload, not for Mars version, but for LEO shuttle version, for empty Starships coming down from LEO, for example for tankers?
Would be cool to have an inner layer that might add weight but if integrated into the tile and wall, could expand into a temporary foam or alternate heat load dissipation mechanism. In the long run a more expensive version would have reactive tiles that interlock more and then fuse more each entry.
SS25 making it to orbit and the booster landing would be an amazing outcome already. If Starship 25 fails due to tiles or whatever is less important, since cost wise, the booster is probably the more valueable bit anyway as it was waaay more engines. In that case would probably already have a semi-viable product if the upper stage was discarded on every flight for a few more years, considering how much more they can lift with it, especially since there is no other rocket that can lift as much as this. After all they can build Starships pretty quickly already. It probably would not be financially viable to launch the next shell of Starlink like that, but they could probably make some money from launching heavy moon or mars gear or DoD stuff with it.
Honestly the whole heat shield issues probably my biggest fear with the reuse ability angle right now. I fully believe SpaceX can achieve it, but I am genuinely worried that if the tiles cannot be made to all stay on and the stainless steel underneath cannot be prevented from melting, then this will massively impact spaceX’s desire for the starship to be rapid reusable.
While some areas like the nosecone or flaps' leading edges call for small tiles such as the current hexagonal ones, I think the body should be covered in way way longer tiles (the longer length parallel to the ship's axis) but still with a hexagonal shape. Such tiles would have many more anchor points and would also be way less numerous. Another idea could be to have such tiles strung in ship-encircling metal wires (or not really strung but the wires running in shallow ruts on the tiles): not to support re-entry heat, but vibrations during lift-off and flight in the atmosphere. Of course, I am no expert and there may be reasons not to make such tiles as I described above. I am just sharing my thoughts.
I wish you guys would make more of these narrated videos. They are really, really good. For those who have moved on from the intense live following it'd be awesome to have some more narrated news/information/etc.
If you pray they will be answered.
@@amdullahaa No reason to bring mythological claims into this. Science and engineering are evidenced based, there is just no need for magical thinking.
Give Marcus House or What about It a visit. Great weekly updates
Agreed
Space Bird did the most badass photobombing.
Heyy NSF, I just want you to know these weekly videos are about as good as Everyday Astronaut documentaries. They're just that good. Please keep em coming.
Thanks! Tim is the king, so that was a massive compliment.
I agree i love these videos.
@@NASASpaceflight Tim is reprehensible, as he's made his content far too much about him and his persona relative to what he's covering. NSF is vastly superior in that regard, except when "Das" is involved. Outside of that, the sheer volume of coverage that NSF provides blows Tim out of the water.
@@MicahTischler I'm not sure to what extreme I agree with you, but I have always detected a level of conceited-ness in everyday astronaut
@@MicahTischler . Hmm. That's a bit harsh. .. "Reprehensible is a strong word describing behavior that should evoke severe criticism." . (Merriam-Webster)
Tile loss from Space Shuttle Orbiter in 1979--those were temporary polyurethane tiles installed for the flight on the back of the 747 from Edwards AFB to KSC.
The loss of Columbia during EDL in Feb 2003 was not caused by tile loss or damage. The carbon-carbon composite leading edge of the left wing was damaged by thermal insulating foam that became detached from the External Tank and caused that disaster.
The tiles were not involved in either the Challenger disaster or the loss of Columbia. The tiles performed perfectly on the 133 successful Shuttle Orbiter EDLs (100% reliability).
Starship has that flexible ceramic fiber mat between the backside of the tile and the stainless steel hull. It could be something like Kaowool 3000 that would provide added protection to the hull up to 2900F (1593C).
If the number of hex tiles on Starship is really 18,000 and there are three fastening posts per tile, that's 54,000 posts, each of which is resistance welded to the stainless steel hull by robotic welders. I would expect at least a few weld failures to occur randomly among those tiles. The probability of a given tile would have two or three defective welds on its three posts is vanishingly small.
Side note: I worked on development and testing of the Space Shuttle tiles during the conceptual design period (1969-70). Later, in 1995-96 I did similar work for the X-33 thermal protection system.
With your experience you seem confident that the tile system will work well in the long run.
quick question could you guesstimate what weight the TPS would be in total?
how heavy would one of those tiles roughly be?
also do they use something to fill the gaps between the tiles?
@@bolgert911 If the density of those hex tiles is 9 lb/ft^3 (145 kg/m^3, same as the tiles on the bottom of the Space Shuttle Orbiter) and the tile thickness is 3" (0.0762m), the surface density of the tiles is 11 kg/m^2. The area of the windward side of Ship (the second stage of Starship) is 793 m^2. So the mass of that heat shield is 8.8t (metric tons).
Good points. It sounds like they are assuming that only two attachments (or perhaps one) are needed to anchor the tiles. This seems hard to assure in the design/testing phase. With the vibration and turbulent flow around flaps etc. it's easy to image tiles becoming dislodged even if only one fastening post fails. Can you get local outward pressumes on tiles? Say due to high pressure under the tiles and turbulence on the outside?
@@marksinclair701 If the flexible ceramic fiber mat that now is placed between the tile backside and the stainless steel hull absorbs water in the humid air at Boca Chica or at the Cape, then it's possible that you could get high pressure under the tiles during the EDL if the temperature of that mat exceeds the boiling point of water.
The tiles on the Shuttle Orbiters were re-waterproofed between each launch to prevent high pressure inside the tile from causing cracks. Also the weight of absorbed water can be several tons. Each pound of water absorbed by the tiles reduces the payload to orbit by one pound.
I don't know how Elon waterproofs the tiles on Starship.
@@rays2506 Fascinating. And this is occuring during EDL? Wondering if the the water would boil off (sublimate?) in vacuum during launch or in orbit. I haven't seen any sign of waterproofing measures between tiles on Starship. Seems like a bigger potential problem for Starship than on the Shuttle - won't the cold tanks condense ice behind the tiles?
It seems like the tiles themselves are capable and well studied in the industry, but rather the tile mounting system needs to be more robust.
This is the biggest issue. Getting the tolerances on the snap on system correct and the quality level high enough to work 100% of the time is very tough.
@@ronwoodward716 I'm imagining a memory metal based fixing that can only ' straight/unclip when Cold enough
Yes.
@@jonbong98 It is my understanding that right now they have to destroy a tile to remove it. A metal frame that contains one way clips is imbedded in the ceramic material the tiles are made of. When installed the posts welded to the ship snap into the clips in the frame. To remove the tile they have to cut a hole through the tile to release the clip because it is buried inside the tile.
There are many possible things that could cause the tiles to pop off. If the barbed top of the post is a little to small or the clip a little to big or the ceramic coating on the frame is filling some of the post hole the post does not properly lock in. The other possible failure mode is the barbed tip of the attachment post breaking off under stress due to stress cracks from forming or maybe the clip edges making a stress rising notch in the barbed post.
What complicates this is the requirement of the attachment system must accommodate expansion and contraction due to tile heating and be robust enough to withstand the vibrations experienced during launch.
@@ronwoodward716 mine too
Your commentary is very professional and the content of the script is concise and on point. You should do more of these discussing different aspects of the Spacex show.
Adiabatic compression :
Have you ever used a hand pump to blow up a bicycle tyre? Have both the tyre and pump at room temperature. Now pump them up until fully inflated, and keep a reasonable pace. You will notice both the pump and the tyre have risen in temperature. This is NOT due to friction, that plays only the smallest part, it's called adiabatic compression.
As the air/gas is compressed together the average energy of that volume goes up, the molecules are buping into each other more often, to reach equilibrium again, it has to radiate that extra energy as heat. Refrigerators and freezers use a related trick. They compresses a gas so it heats up, they use a radiator to get rid of that heat, then decompress the gas in another radiator that is inside the fridge. That compressed and cooled gas, now needs to regain that lost heat, so is takes it from inside the fridge. Same thing and a neat trrick.
Now when a spacecraft slams into the atmosphere faster than the air can get out of the way(faster than the speed of sound), it is compresses the air in front of it. The spacecraft is using the air to slow down, as that saves a lot of fuel, otherwise it could have slowed enough to void the issue all together That air heats up a LOT, a ludicrous amount in fact! It end up radiating enough heat to destroy a spacecraft that does not have adequate protection.
Friction only plays a small part compared to the hinges of hell level of heat generated by adiabatic compression as a spacecraft comes screaming home, so to speak. It's like the heat generated by the bicycle pump compression of the air, just dialled up to godmode level.🥴 If it did not work like that, your fridge and freezer would not be able to chill food at all, the universe is weird like that at times😊🤗
Sorry, it just set me off. keep up the good work😜
While I can picture Starship successfully getting into orbit on its first try, I think it'll take two or three tries to bring it down in one piece. There are just so many "don't know until we try" elements with the tiles as they currently are.
Me to, but a tattered return not a flame through RUD IMO
Tiles are so last century. A better approach would be a thermal blanket witch is deployed on re-entry and it envelops the ship then disposed of by rotating the ship, or once the speed is reduced it could become like a parachute to help with slowing it down further.
Reentering starship is by far the most difficult technical challenge they've tried. They might be stuck on it a while.
Good Summary Video! Even Elon has alluded to his concerns that the tiles may not be up to the task. Myself, I've worked with refractory lined furnaces where the attachments are often the failure point. I am very concerned that the TPS as it looks today is a likely failure point during re-entry due to them falling off during launch and the stress of re-entry. I am confident SpaceX will figure out a solution, but I will be surprised if the TPS isn't involved in a re-entry failure during the first few orbital flights. Hopefully, Starship makes it to that point!
Agree, at the moment they seem to "pop off" as easily as they "pop on" which is the problem, could be rectified with some sort of bolt fixing but they maybe deemed too slow a process for the prototypes. It's a pity the active cooling system wasn't pursued further as long-term it may have been a better solution.
I'm just going to say that yes, I do realize that this is all testing, and that especially early on the shuttle also had issues with it's tiles coming off. However, with the shuttle it was (as far as I'm aware) never the primary black tiles coming off, but the white ones on the tail on the top leeward side of the reentry. It seems concerning to me that they still keep coming off during static pressure testing and not even under the full dynamic load.
I agree the shuttle was a much more rigid frame less flex so they stayed on better.
Quite a few black tiles either cracked or chipped. One fell off and it was only the fact that underneath the tile was a steel antenna element that prevented disaster. Most likely they are coming off because the fragile silica material is tearing away from the mounting hardware - its a hard problem. Also, when you lose a tile, the extra aerodynamic load on its neighbours could lead to a zipper effect.
Yes I am concerned that it could be because starship is so long, with such a flexible straight frame that it could be that is the reason why these tiles are coming off. The shuttle was definitely old and over engineered, but I had a very rigid frame and didn’t go through these Cryotests with cooling or expansion of its frame as much under heat and/or friction. we know obviously starship mustn’t be able to flex too much as that will damage its internal hardware, but inevitably there will still be some with such a long tube frame like this, and those little bits of movement along a body like this where eventually it will add up to a central point, and the effects of the Cryo-tests will inevitably cause tiles to come off. At least that’s what I’m speculating, so this is making me incredibly worried. I really don’t know how SpaceX is going to be able to get around this as I’m really scared this could be some sort of intrinsically inherent problem with all spacecraft that are designed to be able to re-enter the atmosphere. Perhaps it’s one we will never be able to get around. Not until we can actually create a metal body that can survive on its own without a heat shield attached to the rest of the hull, or actually create genuine real energy shields that can hold back the friction heat.
For now, perhaps spacex should try using different shaped tiles in the end for the main body like squares instead.
I'll be happy if the first orbital test flight clears the OLIT and doesn't damage the launch site.
Same. That's all I'm hoping for too honestly.
Very nice Ian and Jack. Informative and covered a few areas we often get questions about in SBL. Again nice job.
THank you NSF team for this deep dive into TPS tiles.
I still don't understand how NSF has just 500K subs ?
Greate video guys!
Good video, thanks. One thing: when you say the underlayer is felt, viewers might get the impression that it's the most common type, which is made of wool. For added clarity, It's actually a ceramic blanket, sometimes called a ceramic felt. It can withstand temperatures up to about 1,250 C (2,200 F) without damage, and doesn't melt until 1,760 C (3,200 F). Pretty tough stuff.
Depends on the type but some can even go higher in temps than that. Fiberfrax 2600 for example. It is designed to go to 2600°F ( 1430°C ) without damage.
The "Heat Shield" issue will be a major conundrum for the Starship for several years to come.
Agreed. I think heat shields in general are the next technology that will lead to a new era of space travel. We're getting pretty good with engines, so we got the "up" part uh... down? Now we have to get the down part sorted out.
This is almost like a professionally made documentary! If this was put on National Geographic I wouldnt be able to tell that it was a youtube video.
The voice doesn't give it away ?
@@chrisbodum3621 Well there are plenty of younger narrators now that sound just like this one on news services.
I mean. at what point are they not considered amateurs anymore? lol
calm, collected, informative.
I love you guys and gals!
One way that the TPS could be tested on a larger scale would be to place it underneath a static fire test. The design of a rocket engine is very similar to that of a supersonic wind tunnel. The exhaust from the raptors is both hypersonic and hot.
I doubt it would be that simple given the impact force of the thrust from individual engines
Most realistic simulation is to simply mount the tiles to the wall of the booster during a static fire. Sound pressure isn't the only reason they can fail. During re-entry there is high dynamic loading, high shear stress, flexing of the vehicle (its not being stiffened by internal pressure at this point) and turbulent flow.
The issue is not whether the tiles can protect against the heat of re-entry, there is not much doubt that they can. The issue is how many tiles will be lost at launch. Too many lost and it will be toast.
They have to fly it to get all conditions. Or spend months in building different test chambers that still won't cover every aspect of flight. They already know the tiles can with stand the heat. Now they need to freeze one side and push starship through the atmosphere and see wut happens.
totally agree with the comments. But remember materials science and design has changed greatly since the space shuttle. But there is only one way to see.
I can't wait to see this blow up on the first launch.
Love these style vids. I do noy have time to watch livestreams but still want to learn, so thanks for these!!
Anther brilliant video. This stuff is priceless, keep it coming please.
Some comments:
- Tiles can fail, crack or fall off during the stress of re-entry. High shear loads, flexing of the body of the vehicle (which won't be pressurised, unlike launch) and turbulence are all in play.
- The mechanism of failure appears to be in the interface between the tile material and the metal embedded in the tile that forms part of the one-way clip. One suspects this interface is too rigid and thus the fragile silica material is tearing from the mounting hardware. Would be nice if SpaceX were more transparent about this.
- The time the Space Shuttle survived a lost tile on the hot side, we were extremely lucky because the tile was sitting over a steel antenna element, which protected the vehicle.
- The felt blanket isn't designed for direct contact with plasma. It will survive some leakage, but it will decompose/ablate if a tile falls off. Worse if a group of tiles falls off.
- There is a progressive failure mode where if one tile falls off, it creates more shear stress on the tiles next to it, leading to a zipper effect.
- If the stainless steel is exposed, it probably won't melt, but it can soften, deform and other more sensitive components may be exposed to high temperatures and lead to unpredictable failure.
SpaceX might be able to remedy this with a more substantial internal reinforcement (the metal embedded within the tile), but this will add weight.
I was quite keen on the original transpirational cooling and there are other methods including a "hot skin" (Rocket Labs is considering this for the feet of its Neutron) and there are hybrid methods involving some active cooling. Those who think Starship will be operational in a year or two don't understand how hard the engineering is.
The tanks will be pressurized during reentry not at liftoff pressure but still pressurized.
@@ronwoodward716 The payload bay won't be pressurized and there is some tricky tile geometry right there.
@@ronwoodward716 That isn't what happens. SpaceX starts with liquids cooled well below their boiling point. Once the engines shut off, the remaining liquid acts to condense the gas (transferring energy out of the gas and into the liquid). Net result is reduced pressure. It can go below atmospheric. There's always an equilibrium pressure, but its not enough to stiffen the tank. Even the header tanks will act to cool the space around them. Plus the cargo bay will be unpressurised.
@@saumyacow4435 The fuel tanks on the Star Ship are balloon style tanks. The walls of the tanks are very thin for their size and weight. That thin structure cannot maintain the desired shape under load without it being pressurized. This is done to save weight. The tanks must be pressurized at all times except during construction. They even pressurize them during transport to the test and launch stands. Once loaded with propellant the fuel and oxidizer constantly boils off to maintain the low temperature. The gas created by this boil off must regularly be vented to prevent the tanks from going over pressure and exploding. Because of this SpaceX has eliminated the cold gas maneuvering thrusters and instead use the boil off gas for maneuvering. The tanks are never below atmospheric pressure. Especially in space because the external pressure is essentially zero. Any internal pressure will act to stiffen the structure of the spacecraft. As for the cargo hold it may or may not be pressurized depending on the cargo. If they ship is carrying people it will be pressurized. For the early launches probably not. If it is not pressurized the inside will be covered with stiffening stringers to carry the loads for launch and reentry. The inside has many structural elements now that are needed to spread the loads from lifting points, flap attachments, engine mounts, fueling ports, valves etc.
@@ronwoodward716 Ok for starters its not technically a balloon tank. It is structurally stable sitting empty, or sitting full of propellant but without pressure, at least until it is accelerated. Real balloon tanks have to be pressurised before they can be filled.
But leaving that aside, you're not differentiating between the booster and the upper stage of Starship. The booster has no insulation and the heat transferred from the surrounding air is significant and will pressurise the contents. Hence you need vents to control the pressure.
The upper stage of Starship is a different thing entirely. For a start, once it is in space, there's no convective heat transfer because there's no atmosphere. Secondly, its heavily insulated which limits heat gain even from exposure to the sun. And in the course of a suborbital flight you're not spending enough time exposed to the sun to compensate for the fact that the propellant is super cooled. It will in fact cause the gas to recondense into the liquid - at least for some time as the liquid soaks up heat.
Whilst the liquid remains cooled well below its boiling point, the equilibrium gas pressure will be well below 1 bar. You need several bar.
Again, if you want it to be stiffened by pressure, you have to have a heater of some sort. And you have to keep generating gas because its not in equilibrium. That gas will still want to return to liquid phase because the liquid is still well below boiling point. And also you need that heat source to generate gas pressure before descent - since you're not going to be using the main engines until near landing.
You can add all the stringers and bracing you like, but the structure will flex during descent. That's a guarantee. Even with pressurisation, the loads during descent are high. The loads exerted on the flaps have to be distributed around the shell. Unless you're going to the extent of having an extremely rigid internal 3D isogrid, its still going to flex. Airplanes do this and they have lots of stiffeners. It doesn't matter a lot because they're not trying to hang on to fragile silica bricks.
Oh and one other thing. Starship will have a large unpressurised volume (for cargo). That requires special attention structurally because it cannot be stiffened by pressure. And its right in the zone where forces from the forward flaps will be transmitted.
Now going back to the original issue. The tiles are clearly failing because there's an interface between the tile material (fragile/brittle silica) and the metal that forms the tile side of the clip mechanism. That has to be fixed. As for the overall structural soundness of Starship. Well, that remains to be seen. You can engineer your way out of it, but the real question is about what usable payload do you end up with? Every tonne of extra structural mass is a tonne less payload. The temptation is unfortunately to push the limits. Not a good idea for prototyping. Its better to over-engineer then figure out where the mass isn't needed later.
Its a pity that Elon walked away from carbon fibre. Maybe he'll go back to it.
I don't think the main heating action is from friction. I think it's from compression.
exactly!
This is correct.
Umm , friction is needed to have compression if air cannot get out of the way it is compressed
@@nilo70 "Friction" does not cause this.
Came to the comments looking for this. IIUC the bulk of re-entry heating is caused by adiabatic compression of the air in front of the spacecraft.
I work at a specialty silica plant! We don’t make aerospace material (I think), but we do make food grade and pharmaceutical grade silica quite often. Very cool process, and the testing is rather involved.
All the current starships are prototypes. I’m sure that some failures are expected. Failures will lead to further testing and redesign. Eventually, they’ll get it right. So don’t lose faith. Expect failures.
Oh absolutely. But also expect that solving this and several other obvious design issues is going to take a lot longer than many believe.
@@javaman4584 I’ll bet that right now, Elon is feverishly working on the TPS . If anyone can solve the problem, he can.
@@javaman4584 Looking at early development of the Space Shuttle they had a very hard time with the tiles, maybe even more so then Starship right now, and considering that Starship is an easier design then the Space Shuttle and NASA got that to work. Well, they'll probably get it
@@rushpuppy2 SpaceX might, but not Elon. He’s an idiot who just pays people to sort things then takes all the credit.
@@rushpuppy2 You seriously think Elon himself is the best qualified person for this? I can promise you a bachelor in art and physics does not make him an expert. There are much more capable men/women out there to try solving this
Great work Ian, Brady, and team. As always.
So Cool! like a "How Its Made" for Tile Installation
Most of the head in NOT from friction but compression (extremely compressed shock waves_)
נכון.
Honestly, I expect the tiles to become a major source of headaches for SpaceX. At least for the first bunch of flights.
Headaches and delays.
Materials-wise the heat shields seem like they're ready, design-wise I feel like they're not at all mature and still have a very long way to go. In the long term I do not think that having 18,000 tiles is practical and I continue to expect them to introduce some sort of external lattice structure to host larger and more reinforced tiles in a more sturdy vibration-resistant manner, which incidentally could also make them easier to service. I think the first orbital ship will 100% burn up on re-entry, they'll learn a ton about what a re-design needs to target, and they'll sacrifice a few more tons on a more robust and dependable heat management system on later prototypes. I think that in 18 months we'll all feel confident about starship's heat management capabilities because they'll have been addressed through failure.
The larger they are, the more fragile they are mechanically. The current setup is three spring loaded clips that hold the tile. I would be surprised if they directly hold the tile material. Rather they should have embedded metal in the tile (its poured/cast) and so its metal to metal contact. However, what's probably happening is that the tile material is tearing away from the embedded metal mounting points. And this is a tricky compromise because you need compliance (spring) to compensate for the tile growing as it heats (It will also tend to grow more on the outer surface than the inner one, causing it to bow outwards as well as expand into the gaps. That puts more stress on those (hopefully) compliant mounting clips.
Bigger the tile, the bigger these issues are. You can make the embedded metal larger and more complex to avoid tearing. But you still have the issue of differential expansion between the materials. What I'm saying here is that there's a reason why they ended up dinner plate size. And of course everything you do to compensate for these problems will add weight.
Love those narrated videos and let's hope it won't happen during the first orbital flight!
I would prefer that we do get some narration during the first orbital flight. :)
Great informational video! Great work!
I think SpaceX are going to encounter much more problems with the tiles than the shuttle did. Once Nasa had worked out how to fix the tiles in place on shuttle, the system generally worked very well - with the exception of being hit by debris of course, but on the whole they rarely fell of or became damaged without something striking them. The shuttle had a fairly stiff aluminium frame, thus the tiles always had a very sturdy and non flexing surface to fix to. This is where I think Starship will have problems, the surface they attach to is not so rigid, just pressuring the ship tends to flex the stainless steel sheets that the ship is made from. Any shock waves the vehicle encounters - from it's own engines for example, will likely travel through the liquid fuel inside the tank, that will be enough to flex the steel. For example think back to the Concorde crash in Paris, that was caused by bits of tyre hitting the wing fuel tank, not hard enough for the tyre to penetrate the tank, but hard enough to send a shock wave through the fuel itself. The shock wave was strong enough to cause the fuel to punch a hole through the tank from the inside out. Of course that tank was just aluminium, Starships tanks a much much stronger, and any shock wave Starship is likely to encounter during normal operation will be nowhere near strong enough to cause the fuel to punch a hole in a tank, but it may well be enough to cause sections of the tank to flex. Which is why I feel Starship will encounter problems - especially seeing that the tiles are only clipped into place. I suspect one reason they are clipping the tiles in place is to try and prevent tile breakage due to the tank flexing. When we see tiles flying off during tests it is hard to tell if they are falling off simply because the shock wave through the tank is enough to unclip them, or whether it is actually breaking the tiles. Will be interesting to see how a full heat shield will perform with a full stack launch.
Exactly well put. I think the flex this ship has is going to be a huge problem
The Shuttle had at least one tile on the hot side that detached and would have resulted in tragedy if not for luck - under the tile was a steel antenna element that protected the aluminium. You're quite right about the flexing of the underlying metal. Starship is basically a big soda can. Very high diameter to wall thickness ratio. Its going to want to flex, particularly on descent where the tanks will be mainly empty and the main tanks unpressurised. Its subjected to high torques from those flaps. Plus there is likely turbulence as the plasma stream shears off the edge of the hot surface and also around the flaps. Turbulence and shear stresses on the tiles isn't good. But it may also prompt a dynamic response from the hull.
The problem with the clips is that on the tile side there would be a piece of metal embedded into the tile so that there is a metal to metal connection. But then there is an interface between the fragile tile material and the embedded metal - quite likely the tile is tearing at this interface. Then you run into a conflict between enlarging the embedded metal (to have more grip on the tile) and introducing more stress from thermal differentials.
@@saumyacow4435 The tanks will still have pressure in them even when landing. The question is will it be enough to prevent severe flexing. That is what the test flights will have to show. SpaceX can always add more stringers to stiffen the hull if needed.
@@gravelydon7072 Nothing to generate pressure. The residual liquid is likely to cause remaining gas to recondense. You need running engines (or a deliberate heater) to generate pressure. There will be flexing. Its a big tin can being torqued by the loads applied by the flaps and subject to the pressure variations caused by turbulence. It may even demonstratw feedback between the structure flexing and the external flow.
@@saumyacow4435 They do not need engines running to create pressure. Just the warming of the fluids to a gas will raise the pressure. Not all the fuel will be out of the tanks before landing. Empty tanks that still had pressure while in space will see an increase in pressure when reentry occurs. It will have to vent pressure when returning.
thank you guys for this one! Really awesome research🚀🤩❤️
Great and well timed video!
Narrated videos are the best content from this channel
I expect the unexpected with the higest probability of RUD during reentry. This is where the try fail learn try fail learn rapid prototyping works. You can only do so much in the lab.
Love this stuff!
I love these commented videos! Please keep them coming!
"How do you think Starship will fare on its orbital test flight?"
-Much better than anyone but Elon could imagine. Starship will most likely be destroyed its maidan flight in one way or another but lots to learn in the process!
"Will everything go perfect?"
-No way, way too many things that can go wrong.
"Will there be a heatshield issue?"
-Based on the tests done so far, I would imagine so. Long way to go in their development but Elon and his team will figure it out.
Much to learn - provided you can instrument and document what went wrong. And that's a little hard on ascent since you don't have eyes on those tiles. And its even harder on descent because even if you instrument, there's no live data stream.
33 Raptor 2 engines putting out over 8,000 tons of thrust. It's going to be raining tiles. Can't wait!
S20 was test fired with 6 raptors and hardly lost any tiles. Ye of little faith!!
I would say based on observing how many tiles crack and/or fall off at 0 knots, that the forces during ascent to include vibrations and supersonic/hypersonic airflows will likely severely damage the tile system. The ship may make it to orbit, but the tile system will likely be in very bad shape.
I think there are actually a lot more vibrations expected near the ground than in the air, so extrapolating from a static fire is hard.
And they haven't tested with the full 9 engines yet.
@@aDifferentJT The aerodynamics on ascent will create serious pressure, turbulence and acoustical vibrations, steering inputs and winds will also induce some flexure in the airframe. Agreed the 33 raptors spitting out hell on earth at the launch pad will also be horrendous.
great video guys reall informative more like this please now that things are hotting up !!!
Great video. Suggestion for next video - mention the mechanism of failure when those tiles fell off. Shock overpressure waves from the engines hitting the structure most likely would not occur when the vehicle is 70m+ away from the engines that will be firing on the Pad. And a totally different mechanism of failure compared with re-entry where hypersonic regime thermal and aero loads dominate.
@nasaspaceflight … “Tile problems” DID NOT “lead to the loss of a shuttle crew”.
Foam shed from the external tank during launch struck and damaged the reinforced carbon-carbon leading edge of Columbia’s left wing. The RCC was part of the orbiters’ overall thermal protection system … and the damage ultimately did lead to the loss of vehicle during reentry … but this incident had nothing to do with the ceramic tiles (a separate component of the TPS).
Tile loss and maintenance was definitely an ongoing issue that significantly slowed flight cadence and potentially risked the safety of vehicle and crew on at least one occasion; but “tile issues” never resulted in such a loss during the life of the program.
I also believe I’ve seen elsewhere that the photo you showed of an orbiter missing a multitude of tiles after a 747 ride was merely the result of having shipped the orbiter with tile installation incomplete. Not tiles just randomly falling off during transport.
great info on the tiles thanks bro...
I am guessing the felt under the tiles is ceramic fibre blanket and the mesh net holding that on probably Nichrome wire? This would be typically used to line the inside of pottery kilns up to 1300 degrees. So it looks like the tiles are also helping to hold the blanket in place against the steel , like a duvet without squashing it flat, also providing thermal insulation behind the gaps between the tiles.
Great overveiw!
Thanks Ian, good job. Cheers
I feel like the tiles go against the whole idea of rapid reusability, they're just not reliable enough. I'd like to see them work on something a bit more advanced than tiles, maybe some sort of composite shell.
The original concept (and part of the justification for stainless steel) was transpirational cooling. I'm working on a concept that involves porous carbon foam (much tougher than silica) and active cooling. Basically, liquid methane is fed into the carbon foam and comes out as hot methane gas. Methane is good in that its heat capacity rises with temperature so its a great coolant.
@Hafgren. Starship is and will continue to be in it's development phase for some time to come. I'm sure that the TPS is high on the list to be refined, but it is hard to know what needs to be improved without conducting a suborbital test. Hopefully that test is forthcoming pending FAA approval.
You must remember these are prototypes they will improve it takes time the tiles on starship are easy to replace anyway
@@saumyacow4435 I think the issue with that would be the extra weight. That's always the issue...
@@ericlotze7724 You are right on one point and that is you are speaking from an armchair perspective. Me, I don't have any armchairs so I'm speaking from my dining room chair perspective.
Really enjoy the channel and the high quality of work you do. If I can make one friendly suggestion: run a mouth de-click on the voiceover. That will eliminate the audible mouth noise. Highly recommend RX9 by Izotope.
The orbital test will be Glorious!!
Merci pour vos excellentes vidéos sur SpaceX
Grerat content! detailed and insteresting stuff.
I expect the first "orbital" attempt to fail on re-entry. In my opinion re-entry is the single most difficult task for any space ship. Making the TPS survive hundreds (?) of launches wow!
I believe that there will be some glitches early on, that is why you do rigorous unmanned testing. If anyone can eventually solve problems it is SpaceX!
"Glitches" is a nice word for "huge explosions".
@@nonconsensualopinion What you said!
If the full stack starship doesn't blow up on the pad then I'll count that as a success, I just want it to clear the tower.
That would make Elon happy as he stated the same for the first launch. Clear the tower and it is a win. Anything past that is gravy.
I think reentry is no problem for these tiles, they were designed to support the force in that direction that basically pushes them in to the bracket they are mounted to. The problem in my opinion is the lateral movement on the pad at launch, they seem to be susceptible to that lateral motion way more and that’s the part of the mission to look at very carefully.
Analysis of the Thermal Protection System was exceptionally difficult for the shuttle, you really had to make sure you had the right cover sheet on your TPS report.
I also really love these videos, please keep making them. 👍😎
I will be both astonished and ecstatic if it even makes it to orbit. Let alone survive re-entry.
No booster has performed a test flight.
I would imagine all those raptors firing up is going to generate quite a shock wave and a lot of noise.
I'm glad finally to start hearing someone talk about the tiles issue, it's been bugging me for ages.
I am sure SpaceX can and will fix any issues but checking thousands of tiles between flights is potentially a big problem for rapid reusability. Especially if you want it certified for human flight.
I can't imagine NASA allowing astronauts on board if even a single tile is missing.
It's always worked going up (99% of the time), but coming down is the issue! Here's hoping...
My favourite NSF narrator. My opinion - not every youtube team member should narrate videos because of his voice and diction.
And don’t forget that unlike the Shuttle that was built from Aluminum which melts starting at 900 deg F. The Starship is made from Stainless steel which retains much of its strength and structure at temp over 2500 deg F.
Re-entry can cause temps up to 3000F, if not more, so…
@@Penfold101 At no point did the Shuttle reach that temp. The boundary air is a different story but it is not in direct contact with the tiles or hull. The black tiles on the Shuttle were rated for only 2300°F. Just the thermal blankets can be higher rated than that.
@@Penfold101 , at 3000 deg F aluminum is a fully pourable liquid, and in the presence of Oxygen will combust. At its melt point of 900 deg F it is beginning to sag. Stainless Steel at 900 deg F is still at full strength, at 2500 deg F it maintains 95% or more of its strength, at 3000 deg F it still maintains some strength. Which would you rather have during re entry? I’d much rather be in the Stainless Steel space ship! The biggest flaw in the Shuttles design was the metal used in its construction.
In which case, for both of you, why are they bothering with the tiles at all for the tons of weight it adds, along with the complexity?
@@Penfold101 Because you need a rigid surface to shield the blankets and keep the heat as much as possible off the Stainless Steel. If you used thick enough stainless, you would not need any TPS at all. But the weight of it would be more than the TPS would be. And that would mean a loss in payload. Ten tons of TPS would hold up better than ten tons of stainless. And with the current design of the TPS, they might also be able after a flight to re-coat the tiles with the putty like compound for another go if there is excessive ablation.
This Narrator is a breath of fresh air!
The tiles are being lovingly crafted as a masterpiece work of art. We need fast much faster, maybe one-piece tps. Change out in under an hour. It's really just an overgrown fairing half made of high temp material.
Don't know till you fly it and reenters. Thanks
Surving re-entry is one thing, but the question is whether the vehicle is left in a quickly re-usable state. It took a while for SpaceX to learn how to weld glorified grain silos that didn't rip apart when pressurized and getting to a stable state involved automated welding equipment. Not sure how well artisanal welding of a patch of new steel over an area damaged by loss of tiles would work next time the tanks are filled.
Once iterative testing/development restarts this year, SpaceX will learn from the failure and adapt.
Note: gap between tiles likely more about steel compressing when loaded with cryogenics and then expanding during re-entry than the tiles expanding on their own.
Man i am obsessed with SpaceX and Starship, i cannot wait for the day we get blessed to see the first flight.
Yet The closer it gets and the more i see of the Catch/Launch tower. I get more and more nervous.
The Starship itself to me isn't my main source of concern. It is the Booster. Much much larger and heavier then SS. I see such a microscopic room for error on the Landing/catch attempt. That booster is about Tons Fueled and about 150 Tons at complete dry mass and about 170-200 At landing. If it comes down to that tower with even a 5 or 6 foot off target or a higher velocity by even a small fraction could lead to an obliteration of 2 years of work in a flash.
During the first Catch attempt the booster will NOT have the same room for error the Falcons had in there evolution or even Starship with its Tests. Both Falcon and ProtoStarship had something that They had Very miniscule to no Surrounding Equipment with the Cost/Time to build ratio that the Booster will have around it on its landing. (IF) the booster were to impact the tower directly, or miss the tower all together i believe would lead to an absolute destruction( or damaged to point of rebuild) of the tower and surrounding equipment. With the Tank farm also so close would be another large worry in the case of a landing failure. I understand, you cannot learn if you don't try, but i never thought of it from this point of view that this thing will have to be almost laser accurate in all aspects for this to end up without utter catastrophe. It will be Success or Rebuilding and designing for the next 1 to 2 years. Thank you NASASpaceflight for all you do for this.
I think they will end up with gluing the tiles as they did with the Space Shuttle.
Fly Starship!
An isolated tile loss should not be catastrophic, but my concern is if a cascade of tiles will peel off. The belly is going to be subject to high external pressure. With a belly tile lost, the high pressure can spread _under the tiles_ to areas with a lower external pressure, thus subjecting those tiles to strain.
[ The thermal blankets will limit flow rate and each tile seam will tend to equalize the pressure difference. But is that enough? ]
Its called the zipper effect and yes its a serious problem. You have to have connectors that are tough enough to just not fail - and that's hard because the tile material itself is very fragile. However you attach it, there's always an interface where the tile can crush or tear.
Its not just high dynamic pressure, its also flexing of the steel (its a tin can basically) and its turbulence.
I think Starship (stage 2) will and should be seen as a disposable stage for many many flights. All focus has to be on getting the booster back given the sheer number of engines it has. + I think they'll come up with some legs for the booster before attempting catches--sacrificing a bit of payload for not destroying your launch site seems reasonable!
This does not have to be an either or issue during this early prototyping of starship. The goal is to bring both back. After all both booster and ship are undergoing constant development.
Space X isn't considering landing legs at this point. Perhaps later. "The best part is no part". EM
Hi guys nasa space flight that was amazing video of star ship showing on how the tiles work it’s a problem to be solved
David 🚀❤️🇬🇧🙏👍
Thanks for the great video, Ian! With regard to your statement that "failure of the heatshield during the first re-entry attempt would not be a setback for Spoacex (since Spacex would have another starship ready to try again)" is debatable. If there's an inherent design problem with the TPS (attachment, fragility, etc) that's a big big problem for Starship. Sending up another Starship with the same TPS design is not going to fix things...
Many are bias regarding tile fragility after close observation of the shuttle activities over the years. We can't even be sure this is the final method of tile attachment since these are still early Starship prototypes. Given what SpaceX has done with F9 booster reentry and dragon reentry one would expect they have a good idea of what it takes to make a sound TPS.
As Ian explains one of the big issues is testing the entire TPS, as a unit, on the ground. The fundamental design of Starship is fundamentally superior to that of Shuttle with regard to surviving reentry for many reasons. Basically where relatively small damage to the Shuttle TPS could result in the loss of the crew, that is simply extremely unlikely with Starship. Starship will survive reentry. What is at risk is whether Starship will survive in shape to be relaunched with minimal investment. To maximize the productivity of Starship it is necessary to maximize payload. Every kg reduction in the dry mass of Starship translates to 1 kg of additional payload. So SpaceX wants to have a TPS implementation which minimizes the mass of the TPS. Designing a TPS in which 100% of the tiles survived launch is desirable, but would result in a heavier implementation. This is why I proposed that one of the Starships from the "Rocket Garden" which has an almost complete set of tiles be placed underneath a 33 engine static fire, the only force on Earth which could possibly test an entire Starship as a unit. This would reveal what will happen when a Starship re-enters with missing tiles. Remember it is not IF a Starship will re-enter with missing tiles, it is WHEN it will re-enter with missing tiles. "Perfect is the enemy of good."
Deformation of steel is a bigger risk for tile damage.
Meaning that steel deformation will damage tiles under stress.
They should find a way to make the heat shield spray-on. Like that expanding foam insulation
That's what I was thinking. Spray it out on entry. Like a burnt marshmallow shell.
A spray on tps has been considered and rejected because it could not handle the heat on reentry.
There has got to be a better solution than these damn tiles! Tile loss has been a severe problem since the early days of the shuttle and apparently haven't gotten any better in the last 40 years. I'm surprised SpaceX, which is known for their "thinking out of the box" solutions went with such an old and problematic method.
You are making an assumption that simply because Space X is also using tile system that it using an old problematic system. The TPS for Starship is very different from the shuttle in having most of the tiles having the same size as well a different attachment system.
Second Starship has a steel hull which is much more resistant to heat then the alternatives. Finally, the effectiveness of the Starship TPS can only be truly tested in an orbital test which is imminent.
I should also mention that your comment offers only criticism of the current TPS of starship, but no suggestions for an alternative.
They *did* think outside the box: originally, Starship was going to use transpiration cooling (in other words: "sweat") using pores in the hull which deposit a thin film of liquid methane onto the skin.
We don't know too much about why they abandoned this idea and went back to tiles, but we can assume that the reason is some variation of *because it doesn't work and tiles do*.
A couple notes - the nonwoven white fabric underneath the tiles isn't felt, that would just be...well.. absurd. It's a type of meltblown/meltspun rockwool or mineral wool, like fiberglass but doesn't melt until the temperature is 800C higher. Also, it wasn't the silica based tiles that doomed Columbia, it was the graphitic reinforced carbon-carbon panel on the leading edge of the wing, used where the highest temperatures were incurred.
This topic is why getting a "one hour" turn around time will be difficult to achieve or maintain.
This and the fact that the engines are highly stressed and complex - another source of inspection/maintenance delays. Have you checked out Rocket Labs's Neutron, for a master class in how to do reusability?
A one hour turn around is well down the road and so not very relevant to current starship development.
@@AdenStewart Ah! Good point! So, another, already prepped Starship could be assembled with the just-returned booster.
I do enjoy the narrative method of explaining the process of developing the challenges that are being dealt with in making a successful and economical space craft. Although it does look like an oversized corn dog to me,. I often thought it would be sweet to just build an oversized vat of the slurry to dip the space ship into it and then stick the hull in an oven to cure the heat shield so it all stayed on and then finish it off at Boca Cica with tanks and fins and pipes and engines. Super simple and fast and sweet~ haha.
Fiberfrax makes a putty for doing just that sort of thing. They also make topcoats that can go to 2800°F. The black tiles on the bottom of the Shuttle were only 2300°F rated.
I'm betting against the first few re-entrys, however I believe so is SpaceX. So I don't see that as a long term problem.
Random tile question: Could those be used instead of the problematic martite under launch stands? They are designed to withstand extreme heat and wind velocities, so they should stand up under the Raptor 2 exhausts, right?
I expect some heat tiles to fall off, but the vehicle to be entirely undamaged and to successfully complete its mission 🤙🏼 Hopefully that means landing at LEAST the starship back in one piece, able to do another sub-orbital flight
Who’s hear after starships re entry during ift3
In Starship’s defense, the stainless steel body can take a magnitude more heat than the aluminum body of the Space Shuttle. And the uniform body will make dissipating built up heat easier. Heat tiles falling off even in patches isn’t much of a concern. It would take large patches of them falling off to really worry me.
Is it possible to make inflatable heat shield for Starship and/or a ballute? Maybe not for when it comes down with any meaningfull payload, not for Mars version, but for LEO shuttle version, for empty Starships coming down from LEO, for example for tankers?
Thanks!
Would be cool to have an inner layer that might add weight but if integrated into the tile and wall, could expand into a temporary foam or alternate heat load dissipation mechanism. In the long run a more expensive version would have reactive tiles that interlock more and then fuse more each entry.
Or a bigger bakery to make a icing on the entire side of the ship as a one piece layer coating. ?:????
SS25 making it to orbit and the booster landing would be an amazing outcome already. If Starship 25 fails due to tiles or whatever is less important, since cost wise, the booster is probably the more valueable bit anyway as it was waaay more engines.
In that case would probably already have a semi-viable product if the upper stage was discarded on every flight for a few more years, considering how much more they can lift with it, especially since there is no other rocket that can lift as much as this. After all they can build Starships pretty quickly already. It probably would not be financially viable to launch the next shell of Starlink like that, but they could probably make some money from launching heavy moon or mars gear or DoD stuff with it.
For the reentry, is it possible to use rockets for speed break to get to a speed when it’s not so hot on reentry?
Honestly the whole heat shield issues probably my biggest fear with the reuse ability angle right now. I fully believe SpaceX can achieve it, but I am genuinely worried that if the tiles cannot be made to all stay on and the stainless steel underneath cannot be prevented from melting, then this will massively impact spaceX’s desire for the starship to be rapid reusable.
One slight problem, reentry heating is caused by immense pressure in front of the vehicle, not friction (as was thought in the early 1900's).
It isn't friction (well, some is friction). The real source of heat is rapid compression.
That's what she said.
While some areas like the nosecone or flaps' leading edges call for small tiles such as the current hexagonal ones, I think the body should be covered in way way longer tiles (the longer length parallel to the ship's axis) but still with a hexagonal shape. Such tiles would have many more anchor points and would also be way less numerous. Another idea could be to have such tiles strung in ship-encircling metal wires (or not really strung but the wires running in shallow ruts on the tiles): not to support re-entry heat, but vibrations during lift-off and flight in the atmosphere. Of course, I am no expert and there may be reasons not to make such tiles as I described above. I am just sharing my thoughts.
It's not felt padding... it's most likely ceramic blanket for additional thermal insulation.
For the shuttle soaking up water was a major concern (e.g after rain). Wondering how SpaceX worked around this ...
Pretty sure it's a secret recipe in the tiles since its engineered to sit outside its entire life.
Good summary, folks.