i agree they really should, it also provides structural stability, as the smoother the finish is, the less micro cracks on the surface where structural failures could start
Its a backup if the "greenpeace-people" fail :D Which will probably be the case. People do not fully grasp the enviromental catastrophy we are heading towards, but these exciting new frontiers, and to go where no man has gone before, THAT almost everyone can understand.
@@HogbergPhotography Is the differentiation between greenpeace and grenpeace-people on purpose? If so, then so do I hope that greenpeace crashes and burns and greenpeace-people succeed.
@@mcbure1 we have those currently. Afghanistan is a complete failure and the embassy having to be evacuated rings of that war. Also Critical Race theory aims to bring back segregated schools
@@starseed96 i dont believe so, its seemingly pointless especially with the fully automated eletric cars that are being mass produced at an affordable price, not to mention its literally impossible to make a floating car that could be publicly available
My favorite ironic thing about choosing stainless-steel nickel alloy is that most intact meteorites are made of iron & nickel. It's like the cosmos has been telling us what to use to get through our atmosphere this whole time!
As an engineer, I love the change! You got it right in that whenever you can change to something readability available today, and ridiculously cheaper, go for it! And ya, engineering is all about compromise. I do feel that the payload won't be affected much. Sometimes we get stuck on looking at one thing (ex. Carbon fiber), but it's always good to step back, and look at other possibilities no matter the initial impression. Sometimes the best answer will surprise you. Which ever engineer or team at SpaceX came up with this solution, certainly deserves a nice bonus. I personally think this change is awesome and will absolutely help make sure this rocket becomes a reality.
iowafarmboy. Not sure who came up with the idea, but Elon insisted on it. It took some time to convince his engineers that this is the way to go. This is typical Elon at his best. He never takes any previous experience for granted and always addresses challenges from a physics first principles approach. If he hadn't done this, we would not be seeing boosters land themselves.
Steve Bothe I totally agree, the fact that the design changed so much is not at all troubling to me, indeed it gives me a lot of hope for the future. It means that Elon isn’t afraid to turn everything upside down in search of the best engineering solution.
@@Matis_747 Agreed indeed. I've linked a couple of videos below, in case you haven't seen/heard them. The first is a podcast of Tom Mueller (SpaceX's chief engine designer), and the second is Dan Rasky, a NASA adviser, talking about how innovative and fast SpaceX move. th-cam.com/video/Uu9sobNjPFY/w-d-xo.html th-cam.com/video/MxIiiwD9C0E/w-d-xo.html
When I worked for Lockheed at VAFB launching Agena Satelites, 5' diam 22 to 35' long, ( Over 350 ) using Thor IRBM boosters , Aluminum, then to Atlas ICBM ( Stainless steel ) , then Titans 1, 2 & 34D ( Aluminum) We nicknamed the Atlas the Reynolds Wrap Balloon because it had to be kept pressurized or kept in a stretch sling in the gantry. As you saw in the video, not in the gantry and lost pressure it fell down. Stainless Steel is 3 times heavier than Aluminum but is 5 times as strong so you can design a tank that is both lighter and stronger. The skin was of various thickness as thin as 0.012 ". The Agena that was on the top of that atlas was returned to Sunnyvale to cleanup the scuffs and dents, run it back through Systems test, return it to the pad, get a new Atlas and launch it, Tough old bird worked fine. Don WW II VET (Launch Systems Engineering Supervisor) Hey everyday Astronaut contact me , I have a lot of good stories and video for you.
Steel, aluminium and titanium have the same strength to weigh ratio but as steel is thinner it's worse when crushed because it just bend. So i think aluminium is better for most structures but when the rocket is inflated the walls are only subject to tensile stress so steel or aluminium doesn't matter...
@@johntheux9238 Completely wrong... when you talk about a meters long piece of metal a few mm doesn't influence how easily it bends. Then there is something as a sandwich panel to take care of that; and that's 2 pieces of metal with foam in between. The foam in between prevents the metal from getting crushed (as you call it). There is no stainless steel, there are a lot of alloys to begin with, then each of the alloys can behave differently in different conditions, then they can harden, which again influences its properties. Then due to handling it can work harden while you transport and use it. The same is true for aluminium. Stainless steel is an alloy, it's a mix of metals, and it's mostly steel, that's why we call it stainless steel. Oh, and i almost forgot to mention nitrogen and carbon can be added by nitrocementation or other processes, further changing the properties. --- The only honest answer you could give as a real aerospace engineer when speculating about a rocket is: _"this could be beneficial if"_ and _"there are many variables unknown to us, so we don't know."_ (I obviously mean an engineer that is not working at spacex, and hasn't signed an NDA)
sasja de vries. Just basic mechanics, two samples with the same tensile strength but one is two times thicker so the material will be twice as far from the center of rotation when it bend. Guess what, the thicker will be stronger when bended. en.wikipedia.org/wiki/Couple_(mechanics)
Yes, please share your stories Don! I'll enjoy listening to them while working on the Nuclear Light Bulb that will get to Jupiter in months, not years. Former ET, Naval Nuclear Power :>]
Steel has a much much longer life as a frame, it's very well known and there are many effective inspection and repair methods. That makes a safer and more predictable frame. A reusable vehicle should be easy to inspect and to repair after each trip.
In my twenties I bought a good quality set of stainless steel pots and pans with lids. They are all still with me and used regularly. I'm in my fifties now. 30 years for cookware is pretty impressive
Steel does not have a fatigue limit, whereas aluminum does. This means that all aircraft which are made from aluminum will eventually fail (same thing with bicycles). Steel will not.
zilfondel When I raced mountain bikes during the nineties, I gave up on aluminum handlebars after breaking enough of them and changed to titanium. Aluminum will eventually develop stress cracks and fail (depending on the specific application) hence why I would never buy an aluminum framed bike. I would only use one if sponsored and getting them for free and will only use steel or titanium; not to mention that aluminum frames are a stiff and uncomfortable ride so they’re really only suitable for bikes with full suspension.
"[...] it's destined for Mars." These words alone give me goosebumbs and make me glad that I'm alive in this century. There's a spaceship being build RIGHT NOW that is supposed to fly to MARS some day WITH PEOPLE ON BOARD. Dude.
Being born in the mid eighties I missed out on the space race and only seen it's stagnation. I got a book from the beginning of the nineties telling about space. Among things are space station freedom. At that was realised as the ISS but the visions of how we soon get to Mars had always been pushed forward. SpaceX and Elon is the first time I feel we are actually getting closer to a manned base and later settlement.
I remember clearly where I was the day we landed on the moon. I was 8 years old. I built models of Apollo craft. After the cancellation of Apollo in my early teens, I watched all our fantasies of lunar bases fly out the window in favor of a finicky LEO shuttle. I am thrilled to have finally lived long enough to see the excitement of space exploration revived.
_Slight_ correction. The actual ship that will go to Mars isn't being built (just an Earth-bound prototype)... but you would be 100% factually correct if you say that it is being actively developed. And that is _truly_ awesome (as in, worthy of awe), because it is the first time in history that you can say that. We aren't sure it'll get done, of course. You have to be a fanboy and/or irrationally optimistic to think this is a done deal. But for once, we humans are actually, undeniably trying to do it. And that is awesome.
I miss being in 4th grade, apart from the fact that I was a terrible student, both academically and behaviorally. I'm very excited for what is to come within the next decade or so. It would be so cool for humans to finally colonize Mars and discover new ways to travel through space faster.
Can also confirm, Source: Am young and EA is probably 50% of the reason for my greatly accelerated interest in space and now I'm planning to go study space engineering.
Agree! Finally we're getting the space ships that mid 19th century showed us. You can't beat that! I'm not a Apple guy but when they released iPhone it knocked the competitors design out the door. Functionally it doesn't matter how it looks but the feeling among the general public will be great. SpaceX might be igniting a great new support and interest for space travel. ... Our ludicrous future indeed...
@@subwarpspeed 19th century? That would have been Jules Verne's giant cannon and bullet. I do believe the BFSs (I refuse to use Elon's stupid new names) should all be named after astronauts and science fiction writers, and the first one back to the Moon should be the SS Jules Verne.
Also remember the falcon spaceship has one of the widest spaceships diameters. Then remember the volume of a sphere increases with the cube of the radius. Because the falcon spaceship is so large it will probably have the lowest ratio of stainless steel to fuel for a given tank size. This should actually make the tank relatively lighter.
?? First, if you JUST made the tank larger, it would have more volume to surface, of course. But that gas NOTHING TO DO WITH the material. It applies whether using steel, carbon, or plasticine. But at the same time, volume equals mass, and mass means forces on tge walls of the tank. That means THICKER WALLS. So a larger tank, in the end, means a LOT more mass to lift per kg of fuel.
@@markdoldon8852 I see what you're saying, and it does seem like my initial thought needs more processing. I do wonder what the final trade-offs would be after you do all the math.
@@markdoldon8852 What is relevant for the material requirement is not absolute force, but pressure (force/area). From the fluid pressure depth equation, the pressure is determined entirely by the density of the fluid, and the height/depth of the tank. Absolute mass or weight of the fluid DOES NOT MATTER. What does change the situation a tiny bit is the curvature of the sides. Since the radius grow, the walls need to have a greater degree of flatness. The curvature does change the ability of the material to support pressure. I looked it up in an engineering handbook that thickness of material need to grow with power 1 with increasing radius, for unchanged pressure. BUT this is probably a really high estimate, since it's meant as a guideline for plumbing, which also need to support it's own gravity - suspended vertical cylinder shape instead of horizontal cylinder shape. Anyway, from geometry alone the mass of steel sheet grows with power 1 from radius (O = 2*Pi*r), while the volume for unchanged height grow with power 2 from radius (A = Pi*r^2). Of cause a change in height will increase both the volume and pressure - so thicker material is needed. But the role of the growing radius in all of this is that the wall mass to fuel mass ratio is a worst unchanged (for pessimist estimate of curvature factor), but for a realist estimate it will improve with increased radius of the cylinder. Btw. I have a master of science degree in physics.
It's alright, sweat just means the rocket is making massive gains. I'm sure they'll make some rocket sweat bands for when it takes that payload to orbit with its massive biceps.
A few really good reasons: * Strength at cryogenic temperatures * Characteristics at high temperatures * Ease of development * Price and you forgot... * Doc Brown's Delorean time machine was made of brushed aluminium
@@AdventistTruth I ruined my own joke. I meant to say brushed stainless steel but I must have written the comment while he had that chart up comparing stainless, carbon and aluminium and I have written "aluminium" instead. Doc Brown's Delorean was the first thing I thought of when he started talking about the reasons for using stainless. D'oh!
"engineering is all about compromise" I wish I had more hands so I could give this 4 thumbs up. I'm going to save this little nugget for my next meeting!
60x cheaper material cost for the hull / chassi. Dude. They might be able to afford TWO or THREE BFR's for the same price as ONE carbon composite BFR. Hell yeah, i'd much rather have two/three chances of success, than one chance. Elon constantly making intelligent changes to ensure the success of the mission.
well elon keeps contact with material sciences and manufacturies. so if they invent new materials or production methods, they know where to find their first customer for their product. also, producing steel used to build high tech space ships is a better marketing strategy than producing steel to make forks :)
He told the same about carbon. Then they made some naive attempt to make a 12m tank of carbon fiber in the back yard and failed. And now they are telling what a wonderful stuff stainless steel is.. didn't know about it before ?
Little lies, stunning shows, people buy, money flows! It just works, it just works, overpriced open worlds, people buy, money flows, it just works. It just works. It just woooorks.
Here is an idea that could work, and save weight. Cool the skin by exploiting the slower-moving air molecules that flow near the surface of the re-entering craft. How? By having slits between 'steps' that faster-moving molecules skip past, but slower ones can enter. This cooler air would be somewhat pressurized, and could be funneled under the craft's skin, and out small holes that are pointed in the same direction as the airflow around the craft. These exit holes would experience almost no pressure, because they would have small grooves in the craft's skin down-wind from them. Maybe use some methane at the higher pressure areas since not much pressure (but more than elsewhere) is required to eject it.
No market for 100 ton payloads?? You got that backwards buddy, when the current launch vehicle limit is a couple of tons then every satellite is a couple of tons by default.Create a delivery system for 100 ton payloads and people will design bigger better satellites to launch on it. No need to miniaturize anything anymore, no more exotic light alloys. It will be cheaper to build a heavy satellite and cheaper to launch on a re-usable rocket.
Yeah, I can imagine some future engineering discussions in startups: 'You say a rad-hardened board certified for 15 years costs how much? ...How about we just encase a few redundant standard PC boards under a meter of high density plastic, do we still fit on the shroud?'
@@guillaumehumbert4545 Cheap satellites have a relatively short lifespan, after which they deorbit and burn up in the atmosphere. Low-Earth orbit is self-cleaning.
What I like best about the major shift from carbon fiber to stainless steel is that it's a reflection of Elon's and SpaceX's willingness to think way outside the box all along the project lifecycle. Most large engineering projects are averse to this agility, turning a blind eye to their discoveries along the way, and sticking to early bad approaches. SpaceX is willing to adopt new technologies without missing a beat - and that says more about the culture of the company than about anything else.
@Angelo Stevens I think because the old tech is now mostly dismissed. Sort of like what Elon did with Teslas. Sure there was proven sound science in that area (albeit definitely more controversial), but no one was utilizing it. The same goes for this occasion. Old and underutilized, but still good; so let's remix it. This is like the space/ rocket version of electro-jazz (or w/e the kids are calling it these days): new and old, all at the same time; and better for it.
@Angelo Stevens Sorry for the wording. I meant the science behind the 'engine' in Tesla cars wasn't being utilized. Steel (in reference to use in outer space) is the 'underutilized' thing... As far as I knew, the engines in Teslas hadn't really been put in to actual effect anywhere. I was under the impression other electric cars used a similar but different engine... I'll look it up tho. ✌ Edit: the bad grammar was killing me, sorry
In this case, they are not afraid to use an old technology that works for their use case, which indicates they are goal and not image driven. A win win in my book. Sometimes, things just continue to be the right thing. In our push towards progress, we have to be sensitive to that, otherwise we will pass up a perfectly good opportunity in favor of something more 'sexy' that, while really nifty, isn't the right thing and will end us up in a failure mode. Learn from the Shuttle folks. Arbitrarily expensive methods are not necessarily the best solutions.
If I remember right, WD40 wasn't used on the Atlas rocket to prevent rust, since stainless steel is already resistant to rust. It was used to prevent a build up of ice formed from condensation on the outside of the rocket. WD stands for "Water Displacement", btw.
Another advantage of steel is fatigue life. As long as you keep the material within the regime of elastic deformation and stay out of plastic deformation (ie do not exceed the yield strength), fatigue life is indefinite. This isn't the case with aluminium alloys - it's why airframes have an "hours limit". For expendable rockets this isn't really an issue, but for a reusable system it will become one.
That depends on the crystal structure of the steel. BCC steels have indefinite fatigue life, but FCC steels like 304 and 310 are susceptible to fatigue just like aluminium alloys. This is because dislocations in FCC metals are more resistant to temperature, whereas dislocations in BCC metals are more resistant to oscillating stress.
Metallurgy student here. At 6:20, just a small correction, cold forming by default is not done at "cryogenic temperatures", it is done near room temperature. The name comes by comparison to the temperatures used during other mechanical forming processes. Not sure about that Elon Musk's tweet about it...
Correct about the common definition, by default. But Tim (and Elon) was referring to a specific new cryogenic process, apparently a quite recent development.
Had meant to correct this. More than likely I am wrong and Rui is correct. What Elon said is a bit unclear - most likely meant that cold-formed (rom temperature) steel has properties that are good at cryogenic temperatures. But I can't say for sure.
Sweaty metal -- reminds me of the Polaris missile nozzle. My father in law was a rocket engineer on that project and showed me a nozzle he came up with which used a sintered first metal (titanium?) filled with a second metal (?don't remember what metal). The nozzle cooled itself by sweating off this second metal as it went providing sufficient cooling for its entire burn duration. He was also involved with rockets on some of the space missions. My Dad worked on projects for the Air Force, and was back at the Cape control room for a few of the Apollo launches . He brought back lots of cool materials for me -- I was really in love with this stuff. PS -- I ended up designing electronics - not as sexy - but it was more economically stable - LOL.
I was a guest at the rollout of the Roton. We got a fairly up close look at the test vehicle and it was definitely a 'novel' design. Actually 'bloody stupid' was what most people called it. But the buffet was good. BTW I never knew I had an ICMB mission critical component under my sink! This was a great episode Tim, one of your best.
100 tons to LEO might sound crazy now but there's a well known principle of "you build it and they'll come" There's not much market for it now but there wasn't a market for digitally distributed media before someone made that an option either.
SpaceX's leaky heat shield isn't a new idea and it's actually quite well proven. The SR71 Blackbird used to leak fuel out of it's leading edges to cool the aircraft at hyper sonic speeds. For a long time they claimed when asked about the leaking that it was an unintentional effect of how the plane was built and that the leaking would stop when the aircraft heated up in flight, but it has since come out this was a lie. In truth the fuel didn't ever stop leaking, it was actually an active heat shield that worked pretty much that same as SpaceX is planning for Starship.
THX 1138 not quite, it routed the fuel through the leading edges wing before sending it to the engine. It was also very special, and very expensive fuel. But it did actively cool the leading edges. It famously did leak on takeoff, but that’s because it needed to heat up to seal the tanks.
Nonsense. Yes, the SR71 leaked constantly. That was not intentional. If they wanted just a leaking fluid, theyd have used something other than highly flammable jet fuel
@@markdoldon8852 JP7 fuel was specifically formulated for the SR-71 and was most certainly not highly flammable! That's why they needed to use TEB to start the engines!
It was the fuel tanks that leaked. Not the lines. It was because the aircraft needed to expand to seal them. They would take off with a light load of fuel, heat the aircraft up then refuel inflight to fill the tanks.
I know the aircraft grew in flight. You could boil a kettle on the tire after the flight. It was made out of titanium. (Which I think the CIA bought through a shell company) it was designed in the late 50’s. And it was really boring to fly. That’s why the pilots called it “the sled”
You know what’s really cool? My physics teacher was the pilot on some of the Space Shuttle missions. It’s incredibly inspiring to learn from someone who was in space!
A few comments here, after having a conversation with a metallurgist (who just so happens to be my father). 1. The cost of the stainless steel depends upon the alloy used (there are thousands - and they're all very very different), but you're still right - the carbon composite process and cost is prohibitively expensive and time-consuming. 2. Another interesting alloy that is what is used in stainless steel ball bearings, which are typically made from 440C (which is too brittle and can cause failure) were replaced with carburizing stainless steel 675 Stainless (a fascinating topic in itself that got addressed after the challenger disaster) 3. Testability for failure was left out. Carbon composites make detecting flaws (especially in a reusable rocket) a tricky business. When you are working with stainless, the techniques are well-established and test are not particularly expensive to run - which would be a consistent expectation before every new launch. It might be an interesting episode to talk about how certain materials can be tested for things like risk of failure - where small defects can be disastrous. 4. WD-40 will (probably) not be required, or anything like that. But we had a good laugh from the animation about the drones spraying the rocket down - that was pretty funny. 2 points for the space humor.
Steel has gotten way more modern, better benchmarks would be CPM S110V or Bohler M390. Theres many other "super steels" and I'm not sure what exactly they would be looking for, but those both make 440c and 675 look like rusted tinfoil. Mostly this has to do with modern manufacturing like particulate metallurgy and the advancement of metallurgy for specialist industries. The addition of elements like molybdenum, cobalt, niobium, and nitrogen have created a myriad of modern steels with different properties.
I love how SpaceX is giving the finger to everybody insisting on the most fancy and complex technology. It is good to see someone go opposite direction of the Space Shuttle craziness. As a fan of Soviet space stuff, I cannot help but see some similarity in philosophy. Both seem to value simple cheap solutions over fancy and expensive stuff. Like the Soviets, SpaceX strapped on lots of small rocket engines, 27 of them on the Falcon Heavy. People used to say for years, that is why the Soviet N1 moon rocket could never fly. SpaceX proved the naysayers wrong and showed lots of small rocket engines work. The Merlin Engine was basically a simple 1960s rocket engine. I like the novelty of taking an old design and using modern manufacturing techniques. It is sort of like designing a new car using T-ford technology, but building it using CAD/CAM, 3D printers and modern material science. Now we got steel! I love it! People have been too into technology for the sake of technology, and forgotten about economics and practicality. Following SpaceX and reading up on Soviet space exploration is partly why I got into reading low tech magazine: www.lowtechmagazine.com . Highly recommend to anybody more curious about using smart low tech solutions to many everyday problems.
well its not that much of a middle finger if you have sunk a lot of money in the fancy stuff previously(composite at space x or the aluminuim chassis in the model 3 XD ). but yeah good to see. ill be looking up the magazine as well.
The tooling alone for a composite ship would cost them close to a billion dollars US and that doesn't include the cost of the materials for the ship itself nor does it include the cost of the autoclaves that would need to be larger in diameter than the parts getting cured. Big money burned quickly.
Its still always a good idea to research and explore these technologies. That is how they become cheaper. No hate towards SpaceX here though, I think this is one of the best idea's they've ever had!
Just don't forget that they still have and the stuff of/in the old command center (y'know, that stuff from the 60's/70's) because it's not as error prone as the new stuff. Same with some "failsafe" Nuclear launch sites from the NAR.
@@Baconator119 Problem is Boeing and Airbus have most of the worlds production prepreg carbon fiber tied up building regular old plastic airplanes. The costs have come way down from when I first started building it where $150 to $190 US per 1 sheet 1' x 1', it cost us millions to build 1 tool for making carbon fiber aerospace parts.
Not sure if mentioned in the comments already, but another big advantage of stainless steel is scalability. Building a 9 m carbon fibre rocket requires big mandrels and and curing techniques that are technically risky.. Going to a larger diameter is capex intensive (new mandrel, more technical risk with curing/delaminations, etc.) Building a 9 m SS rocket is just welding stuff together.. If they can make it work, and the raptor is reliable enough, there's very little holding them back from making a far bigger rocket out of SS. 12 m? 15 m? 20 m? Same manufacturing process, more engines/plumbing, and of course more payload.
The comment about the space shuttle tiles soaking up a lot of heat and radiating it later (around 7:50 in the video) is not correct. Those tiles had an extremely high insulation value. That is the reason why they can be picked up with bear fingers. The material itself has actually taken on a very low amount of energy. When touched by fingers, the energy in the area of the contact points is so low that the skin quickly absorbs it. As the same time, the heat in the rest of the tile (which is still not very much) is so badly conducted, that it hardly flows to the contact areas. Hence: no burns.
oh i think they actually do absorb alot of heat(extreme high temperatures for a long time). They do absorb less heat than stuff like metals though. The reason why fingers aren't burnt when touching the tiles(the tiles being put in an oven until they were glowing hot, pretty sure those tiles absorbed alot of heat then) is because the tiles are really poor conductors of heat, meaning that heat is conducted from the tiles to your hand very slowly, and so your hand doesn't heat up as fast. For example, putting your hands on a piece of metal and a piece of wood, heat from your hand is conducted away into the metal faster than into the wood, which is why you feel metal is cold, wood is room temperature. Both at the same temperature, but one feels cold. Do that for the reverse, the tiles feel alright not because they have little heat but because they conduct heat slowly to your hand. So the tiles do absorb alot of heat, just that they are poor conductors of heat that they conduct the heat slowly to your fingers.
Ok, so first of all, you're awesome. I discovered your channel yesterday and I love it. I just want to mention a couple material properties that you missed. The first is that steel has amazing fatigue characteristics. They might not come into play in this specific use case, but it makes a huge difference in re-usability. The second is the reflectivity thing. On re-entry, most of your heat is coming from friction, not radiation. This means that the shiny, reflective surface (low emissivity) won't make a big difference in how much heat gets absorbed. This does mean though that the surface can't dissipate it's heat well using radiation, because having a low emissivity means that you don't absorb much radiant heat, but you also can't dissipate much radiant heat. All of that said, I'd love it if you proved me wrong. Cheers ;)
Comment on "There's no need for 100 tons to low earth orbit." (paraphrase, about 14:30). Engineers don't design the size of bridges by counting the people swimming the river. One reason ISS kept getting redesigned smaller and smaller is cuz Congress (or the WH) mandated all parts would go up on the shuttle. First plan was to launch a few really big pieces on disposables ("disintegrating totem poles"), then do all the rest with shuttle. That wasn't acceptable to the political leadership at the time. If the capacity is there, it will be used.
@Aquarium Fuzz - I couldn't hope to put it better myself! I also say, that weight is one matter, SIZE is other. Booster of this size should be able to deploy telescopes with 8m unitary mirror, like ATLAST concept. Moreover, 100t to LEO is far less when GEO, Moon, Mars are concerned.
@@piotrd.4850 - it's kind of ironic that one of the most limited resources in space is ... space. An enclosed volume that can be used as a shirt-sleeve environment is hard to come by, because it most either be aerodynamic for launch thru atmosphere, or expandable once on orbit (see SpaceHab). Cavernous multi-room quarters for spacecraft personal (See Star Trek for examples) is such a laughable hollywood concept.
Elon seems to have implied funding BFR is something of a challenge. I imagine being able to make it happen for cheaper sooner is very good in their books when R&D for cutting edge rockets tend to be very prone to ballooning costs and timelines. SpaceX has always been about financial viability from their start, this is exactly their way of doing things. Don't do what is the craziest and highest tech, do what balances all the equations, including the money.
yes, old tech is constantly being "replaced" by new tech, but old tech patiently waits to be "re-discovered", especially when it's only 1/60 the cost!!
@@TheFailedmessiah A second word (well, acronym). SLS. At this point there's no chance we'll get more than about two launches out of it, for minimum $40 billion.
I instinctively knew or inferred some of the reasons why SpaceX moved from carbon composite construction to stainless steel, but you made it all crystal clear. Thank you for this presentation. You did a fine job.
Best video you did so far! I love it and woul'd utterly enjoy more content like this. Luckily there is much going on right now in the space sector so there is tons to learn and talk about.
I actually considered content on this channel not worth my time, because alot of "101 basic stuff", and repeat what i already know from other sources just reasoned more easy. But this actually gave more of the technology part described for dummies. But still enjoyable for giving insight in the technology they are going to use/technological challenges they had to overcome.i'm not a technoguru, but he also does target the average joe so i don't blame him. Thanks for the update.
I'm so glad he toned down the shrill, hyper, style he used to do. Still was expecting a very basic overvew, instead got a well researched and well reasoned analysis. Good job.
SpaceX engineer: Alright Elon, cool idea with BFR, but there's no way we can belly flop this thing without cooking everyone. Elon: What if we just set the belly on fire?
Added bonus: If it is used in an oxygen-rich atmosphere, the fuel would actually combust and expand, which would give a small amount of extra "drag". With some smart mechanisms on the fuel flow this could even be employed as RCS on re-entry to provide attitude control.
@@Stoney3K seriously though, re-entry temperatures are so hot that "combustion" kinda stops being a thing, as everything's a plasma. By the time it stops being that, it's well behind the rocket, in the re-entry trail.
@@kargaroc386 That means it doesn't react with the oxygen in the air during re-entry? After all, a flame is a plasma just as a re-entry shockwave would be. The contribution it would have to additional drag would probably be questionable though.
Let's not forget the ease of repair! You have to consider the fact that these ships are going to fly to some rough and remote places. If carbon composites break or create a fracture, it's very difficult, if not impossible, to repair. With stainless steel, however, you can just weld it on the spot.
On the other hand, composites have a structure that resists propagation of cracks, whereas metals tend to do the Comet thing: rip like crazy. I'm not sure what they intend to do about this sort of thing with stainless...
@@AttilaAsztalos Metals typically used in aerospace like aluminium have bad fatigue characteristics you are right, and eventually just fall apart as cracks propagate through their structure. Steel is much more better in this respect and has a fatigue limit of about 1/3 of its nominal strength if remember my old engineering course correctly... That means that after a lot of load cycles the actual strength of steel tends to 1/3 of its original value. So if you design your structure to withstand at least 3 times the expected load you should be safe from fatigue issues, albeit with a weight penalty...
I just showed your video to my physics class. That's why I love your channel. You keep it clean so I can show it to students. Also... Elon replied to one of my tweets which was a reply to one of your tweets. I can die happy now.
What an incredible video. This has to be your best yet. Great presentation of your extensive research, great reasoning behind everything you armchair engineered. Really impressive stuff and most of all super entertaining!
@@JJayzX Scott is a great TH-camr who offers a somewhat more technical perspective. Tim is the everyday astronaut because he wants to explain it to everyday people. So what if Tim watched Scott's video? He wants to make it easy for people with 0 technical background to understand. He wants to introduce space to a new audience.
Always been a little proud. My uncle actually helped design those ceramic heat tiles on the space shuttle. Vital to reentry and keeping our men and women safe while landing. :P
If I remember right, WD40 wasn't used on the Atlas rocket to prevent rust, since stainless steel is already resistant to rust. It was used to prevent a build up of ice formed from condensation on the outside of the rocket, so the application of drones for the application still applies! ...WD stands for "Water Displacement", btw.
I love this video! I am a big fan of using steel when it makes sense. Being a hobby custom bicycle frame builder, I have found that carbon fiber composites are commonly used as a buzz word material to sell products for higher prices. Who needs carbon gear shifts and dashboards, except for bragging? Carbon is commonly wrapped over cheaper materials such as aluminum to fool the consumer. "Steel is real".
Yup... once all factors are taken into account, Steel can be really hard to beat even when weight is a consideration. Stiffness matters a lot, and increasingly, so does "printability", and strength when printed. Stainless actually gains strength when it is printed, as does certain grades of Titanium,and for items that are going to be re-used over and over again, fatigue strength also matters, and also favors using steel over less dense materials.
@@63turbo That's an interesting point - being able to print replacement parts is incredibly useful. If we are going to the Moon and Mars a delicate system that kills everyone if it gets slightly damaged (during re-entry say) is not good enough. But with a steel ship and printed steel parts you can do running repairs which has to be a very good thing!
People definitely get hyped about carbon everything, saw it first hand building carbon drag car bodies. But I'd rather have a carbon fiber surfboard than a stainless steel or aluminum. Sometimes you just can't compete with very light weights.
Well, as I'm sure you know as a bicycle frame builder, carbon fiber is significantly lighter and has a much higher strength to weight ratio than steel. It may be a "buzz word material", and most people that use bikes probably don't need it, but it is empirically superior to steel in the vast majority of use cases. I suspect you don't like carbon because you build bikes out of metals like aluminum, and carbon fiber demand is cutting away your customer base, but please don't act as if it is snake oil that "fools" the consumer when it is actually a superior material.
About the same payload capacity as the Saturn-V is a good number. Energia is close, and the Shuttle stack does this too, but less of it is useful payload. There are innumerable potential near-term applications for ~100 tons to LEO. And it's smaller than we should be pushing rocket design for. Sea Dragon was to be simple steel 2STO for ~500 tons to LEO. There were lots of post-Apollo "Nova" and some during the studies about SSPS systems for which ~300 tons might have been the starting point for 1 or 2 STO designs. Rockwell Star-Raker SSTO plane was for 100 tons, in a standard cargoplane or flat-bed sized load arrangement. There were never any severe technical problems about these. As with the Saturn-V and NERVA engines, they represented an embarrassing excess of capability to an agency and government which had no ambitions post-Apollo at all. That's not the way space must always be treated. Musk is proving that to be so. We've been artificially held back despite ample public support for a real space program. We're used to thinking small and having no lasting funding. We were made used to treating space like that.
Thanks for another great video. It seems odd that anyone would criticize SpaceX for solving the problems that it needs to in order to make this rocket a reality. When the first one orbits the moon or lands on Mars will that accomplishment be lessened by what it is made out of? I’m on team make it happen. Build it out of adobe if that is what it takes.
At first I read this as "adobo" as in "adobo peppers," and thought that was odd, and then realized it said "adobe," but then I thought about Starship being built out of Adobe Photoshop, and then I finally realized what you meant. I need an adobe ship in my life.
@Maxwell Adams We hear a lot about how many cool new materials are invented, a few years back everyone was hyping carbon fiber for example, lastly I heard much about graphen getting popular (which has even less industrial use), but you hear much less about how much we can actually do with steel. Then people are surprised that Elon uses good old stainless steel. Since all the stuff his innovative companies build seems so futuristic, we generally expect them to create and use some cool new carbon fiber or composit materials, but no. STEEL. To those who works with and know materials that Was no real surprise, that's what I meant. Steel in general doesn't have many special qualities, compared to some materials out there, but it has by far the widest range of application. Good for us, it also happens to be made of the most common elements
Can you imagine us not sending not 1, or 2, but 10+ ships to Mars on the first attempt? If something goes wrong, it would be much easier to fix it if 2 ships could meet mid journey. Imagine if 1 ships was used as a fuel tanker. Think of the possibilities. If all else fails, and a ships has to be abandoned, a crew might be able to perform extremely risky and dangerous ways to get into another ship. Backups of backups, just in case.
@@johnathangoodwin3610 A fleet, I like it. Just like in the great movie "The Martian Chronicles" starring Rock Hudson. Hey, they were shiny rockets too!!!
Great content Tim - I think, as a credit to your content, the people who complain about “too much Kerbal” simply wish every video of yours was like this - although of course it’s impossible to churn it out all the time ;) they should just filter themselves. This is epic stuff though - everyone agrees.
If spacex succeeds and BFR becomes a game changer in terms of how cheaply you can put suff in space, why not use that lift capability to assemble a BFR carrier, a spaceship designed for interplanetary travel only (no landing) and then land multiple BFRs on Mars at once?
@@MarkLLawrence I built exactly that a few days ago in KSP. With reusable interplanetary ships it just makes sense to not let them land but keep them in orbit at all times.
The SR-71 was another wet aircraft but not for cooling or defrosting purposes. When the plane got up to speed in flight, the increased friction with the air would cause it to heat up and the metal to expand. The fuel tank was intentionally designed to have gaps that would leak but would then seal together once in flight due to expansion
@@AcButeo the F-35 is a good plane, but continuous changes in the requirements made the development expensive. Yet today, it is cheaper than some 4th gen aircrafts.
Rewatching this 2 and a half years later, after Tim's excellent 3 part interview with Elon at Starbase, August 2021...so much has changed, but not the core mission and it shows in all the right ways.
I think the stainless steel design is more like an engineering miracle than the carbon fiber version was turning out to be. SpaceX is famous for getting more bang for the buck. The stainless steel design does that.
Great guitar! Watch that capo being left on though! I had a Eric Johnson Strat with a maple neck like that and I left my capo on one day and it left a dark line I could never get out of the finish! Just a heads up! Love ya man!
I looked in comments to say the same, I'd love one of those things (a '69 model though rather than the '72) but leaving the capo on and leaning it at a steep angle on a wall is criminal!!! (I used to be a live soundmixer and sometimes helped the roadies out when we were busy and that would be a sacking offence.)
The RS25 engine used a transpiration cooled faceplate for the injectors made from sintered stainless steel Rigimesh as well. Transpiration cooling is not new either.
John theux no, to go into the future. Find the one that is going to slip in undetected and wipe out life on earth. You then can use computers to determine based on its future trajectory where it is today and send a mission to annihilate it while it is far enough away to not present any danger.
Hi, Tim. There's one thing that's been bugging me since the steel starship was presented, with the support that steel resists better to heating and thus needs less protection (less weight in heat-shield)... It's that, even though a steel frame resists better to the heating, it will still heat up more, specially if there is not as much heat-shielding. What about all that is inside this baking-hot spaceship, like instruments, life-support systems and ultimately, crew and passengers? In a spacecraft made of aluminium or carbon composites, the thermal ceiling will be at about 300°C, and needs a sturdy heatshield, to avoid damaging the frame and the interior. Well, if a steel frame allows the thermal ceiling to be raised to 800°C or more, that's still much below the plasma-creating temperatures of the surrounding air during re-entry - so, a heat-shield should still be necessary. This begs two questions: 1st - won't methane cooling of the heatshield heat up the methane to unstable temperatures and expand it drastically due to heating, thus loosing it's thermal conductivity and cooling ability of the heat-shield? 2nd - won't it be difficult to manage overheating of the frame if it's allowed to heat up to 800 degrees or more, mainly because the interior must always be at or below 25 degrees? Thanks in advance for your time.
Thanks Tim! I've been following SpaceX closely and thought I understood the new system pretty well. You still offered some good insights that I didn't know about such as the cold forming and the sweating metal.
I remember having to wash down an entire SR-71 when I came in drunk, so the punishment for someone who screws up at Space-X will be to polish the rocket ;)
I like it even more with active heatshield, its more robust, eazy to repair (in space), and more reusable (nothing is oblative (engine or heatshield))!
Its called a "weeping wing" on the DA42 light twin. And it lets small aircraft finally gain anti ice capability at a low cost. Normally light aircraft pilots had not ice protection at all. So it seems to be a very functional very affordable plan.
Excellent video, full of solid facts. 10:05 This "sweaty spacecraft" idea is not new. I read about it around 1962, probably in the magazine "Flight", when various re-entry schemes were being considered. It is very reassuring to see Space X taking advantage of the entire canon of space knowledge and experience, something young scientists in other areas are often not doing in their fields.
Stainless steel is much cheaper than carbon fiber on a per kilogram basis, HOWEVER you require a greater weight of stainless steel to replace the same containment strength as the much lighter carbon fiber - and stainless steel also increases the weight of the vehicle. So your $180/kg versus $3/kg comparison is highly misleading without accounting for these two factors.
As Tim explained in the video, in mission conditions the actual strength to weight ratios do not differ that much. At the end of the day, the given concept might only work with stainless steel, while another one would work best with carbon fiber, which makes comparing costs somewhat complicated. However, Tim was clear about only comparing the manufacturing costs and at this point he is right without any question. All the best, Joe
totally agree. you're devoting a lot more of your fuel just to lifting the ship itself. Also, I don't really get the price argument when talking about a reusable vehicle. I really doubt price was a factor in this decision.
@@xordus Hi Matt, weight is actually a pretty complex issue. On the one hand, it depends on the strength to weight ratio, which is according to Tim similar for carbon fiber compounds and the used stainless steel in operational conditions (I haven't checked that myself, however). On the other hand, the designs in which CFCs would be used and those in which stainless steel would be used differ significantly. For instance, CFC designs would need to include an extra ceramic heat shielding, while this can be avoided and hence mass saved by using active cooling in a design utilizing stainless steel. Therefore, the overall mass of the vehicle more depends on how well the fine-tune between chosen design and used materials is, rather than materials alone. I agree that the lower cost of stainless steel compared to CFC was probably not the main reason for choosing the first. However, SpaceX was and still is very consistent in its approach to avoid unnecessary cost and built everything as cheap as possible in order to create a larger market for their services. Hence, it does not come as a surprise to me that material costs are a point of concern for them. Thanks, Joe
@@xordus Well even it's reusable if the vehicle is three times cheaper to make then you could have 3 starships for the price of 1 so more launched which equals more money.
Correction @ 6:27 - cold forming is simply done at room temperature as apposed to a malleable state when red hot ! hence the term 'cold forming' - its not to do with cryogenic temperature
The term cold forming as you mean it applies to a lot of materials/uses. Tim was referring to a specific type, specialty cryogenic cold forming. But he should have made this clear.
your assumption is accurate and it does indeed apply to sheet metal. square tube & other parts are often much easier to shape while hot, but there are reasons that it's reasonable to choose to do it at room temperature, in which case it's called cold forming.
Aircraft have had that leading edge deicing capability for decades and it's called a weeping wing system. A mix of innovative technologies and proven engineering is a good way to move forward!
Many people tend to think that "new materials = better, cheaper, hightech", but old materials aren't outdated as they may think. The wood, bamboo, steel and even bones keep getting new hightech uses where they literally outmatch the new materials. :)
Yeah, I wonder about this - and it's not just the looks. If discolored by Mars aerobraking, would it not have enough shiny radiative heat property for Earth aerobraking.
Look at those nozzles on the rocket engines. They are iced over with all that heat blasting on them. They will probably keep the stainless steel cool enough that it will prevent discoloration.
It will look even cooler IMO. And it won't affect radiative heating protection property since it's mostly infrared you need to reflect. The rainbow discoloration only affects visible light range
Hey Tim! I'm wondering as we're heading to the first almost-orbital launch of a Starship combo. Is the sweating stuff still planned? And do we know if they will use the refregerative cooling for this test (sn20) or later and just stick to the tiles for this first try?
I'm not sure Elon meant coldforming AT cryo. At least that's not something I've ever heard of before. I think it was meant as normal coldforming of steel sheets which just means forming the metal at temperatures below recrystallization temps. The forming of the metal increases the amounts of dislocations inside the lattice structure. Dislocations hinder the movement of atoms along the lattice structure which in effect increases the strength of the material. If the metal was over recrystallization temperature, the dislocations would disappear as the crystal reforms. So the problem with cold forming is that the metal gets harder and harder and thus harder to form, especially if you have to apply stress over a long roller. I guess that is what Dawson engineered and can handle now. The cryogenic part I think is referring to cryogenic hardening. So after hardening you cool the metal to cryogenic temperatures. This helps transform rests of austenite to martensite and furthermore creates a high density of gaps in the lattice structure which can be filled with special carbides that form during a subsequent tempering process. This further increases strength even beyond martensite. This is a fairly new technique and I'm not sure it has been done to parts as big as rocket fuselages yet. I actually think using steel or even aluminium is a smarter choice for reusable rockets. Unlike metals, carbon composite parts fail catastrophically without a lot of forewarning since they do not really deform before breaking. They just get not visible micro fractures and suddenly they fail. Metals on the other hand will deform first which gives them a little bit of extra time to work and hopefully fix before a part breaks. So if a rocket lands an inspection should relatively easily find parts that are about to fail and can be replaced preemptively. Disclaimer: That said I'm not a metallurgist either. So my knowledge is limited to the material science class I took during studying engineering at university, which was not my personal focus.
Actually, there *has* been cryogenic rolling, forming and treatment for over a decade... it is only recently that the process and uses are coming more mainstream. It has very specific applications and for a long time was very low volume... but uses have caught up with the tech as prices have slowly dropped... I worked at a plant that did exactly that for one quarter out of the year for certain customers.
@@edwardpaulsen1074 Indeed, cryoforming of austenitic SS dates back to the 1970s at least. Despite our modern association with "cryo", it means temperatures below ambient, so not necessarily super-cold by our modern us of "cryo", but also much colder than most of us would call "sub-ambient". IIRC, and I may not, you only need in the -150 to -200 degree Celsius range for austenitic SS to hit the optimum deformation needed. Once you hit the deformation temperature range the type of strengthening is dependent on the type of stress you apply. Also I seem to recall something about the metal getting even stronger after "aging" - which meant getting heated up "above ambient" not just let lie around. If memory serves 304 specifically was noted to have strengthened further after being heated up to a few hundred degrees. Again, take the above with some grains of ambient temperature NaCl, as my memory may be off a bit here and there on the finer points.
I really hope the final ship is polished to a mirror finish.
Chrome with flame? That would be cool🤣
i agree they really should, it also provides structural stability, as the smoother the finish is, the less micro cracks on the surface where structural failures could start
@@tamasan5374 lmao
tbh i think it will because the shinier it is the more heat it can reflect so the lighter it can be
Layers of kevlar and steel could work carbon outer layer for better heat dissipation
If people ask: "What are space programs good for?"
My new answer will be: "They gave us the glorious WD-40"
Not to mention GPS.
@@Nevir202 hammer,ducktape and WD-40 for sure can fix even GPS!
And Velcro! And hundreds of other innovations!
Its a backup if the "greenpeace-people" fail :D Which will probably be the case. People do not fully grasp the enviromental catastrophy we are heading towards, but these exciting new frontiers, and to go where no man has gone before, THAT almost everyone can understand.
@@HogbergPhotography
Is the differentiation between greenpeace and grenpeace-people on purpose?
If so, then so do I hope that greenpeace crashes and burns and greenpeace-people succeed.
People on the 60’: Starships will look like this.
People on 2000: nah, they wont.
20’ Elon: oh, the hell they are.
Hahaa
@@mcbure1 optimism about the future. hopefully.
Please, don't let your Fender Telecaster guitar in that position, you demage the arm.
Sorry, I write from Monterrey, México.
@@mcbure1 we have those currently. Afghanistan is a complete failure and the embassy having to be evacuated rings of that war. Also Critical Race theory aims to bring back segregated schools
Yeah not really. The steel is going to be covered with insulation. Derp.
Elon Musk is literally making those classic old 60's esque space ships into reality.
Thats secretely his real plan
In 10-15 years we'll also have flying cars
@@starseed96 i dont believe so, its seemingly pointless especially with the fully automated eletric cars that are being mass produced at an affordable price, not to mention its literally impossible to make a floating car that could be publicly available
Elon is a demon, don't be deceived
@@nicholasjohnson6724 ok dood
My favorite ironic thing about choosing stainless-steel nickel alloy is that most intact meteorites are made of iron & nickel. It's like the cosmos has been telling us what to use to get through our atmosphere this whole time!
Sometimes the most complex questions have the "simplest" answers.. Gotta love how this universe works
or its the fact they are hard to vaporize unlike other materials
@@brandondumont7223 If I was re-entering Earths atmosphere, I would prefer to be hard to vaporize over easy to vaporize, but thats just me.
yes sir, that was, very very IRONNIC....kel thing....
ok, which one is exit door please?...
The Chromium content is what gives it the extra zing...and molybdenum in 316
As an engineer, I love the change! You got it right in that whenever you can change to something readability available today, and ridiculously cheaper, go for it! And ya, engineering is all about compromise. I do feel that the payload won't be affected much.
Sometimes we get stuck on looking at one thing (ex. Carbon fiber), but it's always good to step back, and look at other possibilities no matter the initial impression. Sometimes the best answer will surprise you.
Which ever engineer or team at SpaceX came up with this solution, certainly deserves a nice bonus. I personally think this change is awesome and will absolutely help make sure this rocket becomes a reality.
In his interview with Pop-machanics, Elon said it was his idea and that it took a bit of effort to convince his people.
What I find the most ironic is that aesthetically the 1950s sci fi world is having the last laugh.
iowafarmboy. Not sure who came up with the idea, but Elon insisted on it. It took some time to convince his engineers that this is the way to go. This is typical Elon at his best. He never takes any previous experience for granted and always addresses challenges from a physics first principles approach. If he hadn't done this, we would not be seeing boosters land themselves.
Steve Bothe I totally agree, the fact that the design changed so much is not at all troubling to me, indeed it gives me a lot of hope for the future. It means that Elon isn’t afraid to turn everything upside down in search of the best engineering solution.
@@Matis_747 Agreed indeed. I've linked a couple of videos below, in case you haven't seen/heard them. The first is a podcast of Tom Mueller (SpaceX's chief engine designer), and the second is Dan Rasky, a NASA adviser, talking about how innovative and fast SpaceX move.
th-cam.com/video/Uu9sobNjPFY/w-d-xo.html
th-cam.com/video/MxIiiwD9C0E/w-d-xo.html
When I worked for Lockheed at VAFB launching Agena Satelites, 5' diam 22 to 35' long, ( Over 350 ) using Thor IRBM boosters , Aluminum, then to Atlas ICBM ( Stainless steel ) , then Titans 1, 2 & 34D ( Aluminum)
We nicknamed the Atlas the Reynolds Wrap Balloon because it had to be kept pressurized or kept in a stretch sling in the gantry. As you saw in the video, not in the gantry and lost pressure it fell down. Stainless Steel is 3 times heavier than Aluminum but is 5 times as strong so you can design a tank that is both lighter and stronger. The skin was of various thickness as thin as 0.012 ". The Agena that was on the top of that atlas was returned to Sunnyvale to cleanup the scuffs and dents, run it back through Systems test, return it to the pad, get a new Atlas and launch it, Tough old bird worked fine.
Don WW II VET (Launch Systems Engineering Supervisor) Hey everyday Astronaut contact me , I have a lot of good stories and video for you.
Steel, aluminium and titanium have the same strength to weigh ratio but as steel is thinner it's worse when crushed because it just bend. So i think aluminium is better for most structures but when the rocket is inflated the walls are only subject to tensile stress so steel or aluminium doesn't matter...
Great story, Don, thanks for sharing. We definitely want to hear more. Everyone like this to the top so Tim can see it!
@@johntheux9238 Completely wrong... when you talk about a meters long piece of metal a few mm doesn't influence how easily it bends.
Then there is something as a sandwich panel to take care of that; and that's 2 pieces of metal with foam in between. The foam in between prevents the metal from getting crushed (as you call it).
There is no stainless steel, there are a lot of alloys to begin with, then each of the alloys can behave differently in different conditions, then they can harden, which again influences its properties. Then due to handling it can work harden while you transport and use it. The same is true for aluminium. Stainless steel is an alloy, it's a mix of metals, and it's mostly steel, that's why we call it stainless steel. Oh, and i almost forgot to mention nitrogen and carbon can be added by nitrocementation or other processes, further changing the properties.
---
The only honest answer you could give as a real aerospace engineer when speculating about a rocket is: _"this could be beneficial if"_ and _"there are many variables unknown to us, so we don't know."_ (I obviously mean an engineer that is not working at spacex, and hasn't signed an NDA)
sasja de vries. Just basic mechanics, two samples with the same tensile strength but one is two times thicker so the material will be twice as far from the center of rotation when it bend. Guess what, the thicker will be stronger when bended. en.wikipedia.org/wiki/Couple_(mechanics)
Yes, please share your stories Don! I'll enjoy listening to them while working on the Nuclear Light Bulb that will get to Jupiter in months, not years.
Former ET, Naval Nuclear Power :>]
Steel has a much much longer life as a frame, it's very well known and there are many effective inspection and repair methods. That makes a safer and more predictable frame. A reusable vehicle should be easy to inspect and to repair after each trip.
In my twenties I bought a good quality set of stainless steel pots and pans with lids. They are all still with me and used regularly. I'm in my fifties now. 30 years for cookware is pretty impressive
Steel does not have a fatigue limit, whereas aluminum does. This means that all aircraft which are made from aluminum will eventually fail (same thing with bicycles). Steel will not.
zilfondel
When I raced mountain bikes during the nineties, I gave up on aluminum handlebars after breaking enough of them and changed to titanium. Aluminum will eventually develop stress cracks and fail (depending on the specific application) hence why I would never buy an aluminum framed bike. I would only use one if sponsored and getting them for free and will only use steel or titanium; not to mention that aluminum frames are a stiff and uncomfortable ride so they’re really only suitable for bikes with full suspension.
@@zilfondel Steels most def have a fatigue limit. Its just much higher than that of aluminium.
@@haraldhimmel5687 steel is just much..MUCH. tankier.
"[...] it's destined for Mars." These words alone give me goosebumbs and make me glad that I'm alive in this century. There's a spaceship being build RIGHT NOW that is supposed to fly to MARS some day WITH PEOPLE ON BOARD. Dude.
That's crazy, 2 years ago i wasn't even expecting the human kind to go to the moon again, and now we re going on Mars
Being born in the mid eighties I missed out on the space race and only seen it's stagnation. I got a book from the beginning of the nineties telling about space. Among things are space station freedom. At that was realised as the ISS but the visions of how we soon get to Mars had always been pushed forward. SpaceX and Elon is the first time I feel we are actually getting closer to a manned base and later settlement.
The hype us space enthusiast are feeling these days is hard to measure, this will be beyond cool
I remember clearly where I was the day we landed on the moon. I was 8 years old. I built models of Apollo craft. After the cancellation of Apollo in my early teens, I watched all our fantasies of lunar bases fly out the window in favor of a finicky LEO shuttle. I am thrilled to have finally lived long enough to see the excitement of space exploration revived.
_Slight_ correction. The actual ship that will go to Mars isn't being built (just an Earth-bound prototype)... but you would be 100% factually correct if you say that it is being actively developed. And that is _truly_ awesome (as in, worthy of awe), because it is the first time in history that you can say that. We aren't sure it'll get done, of course. You have to be a fanboy and/or irrationally optimistic to think this is a done deal. But for once, we humans are actually, undeniably trying to do it. And that is awesome.
My grade 4 students love watching your videos. They are getting excited about the future and space.
That's fantastic!!!!
That's awesome
Thank you for getting them interested!
@@johnsanvictores6639 I love to teach students about what I'm learning and passionate about.
I miss being in 4th grade, apart from the fact that I was a terrible student, both academically and behaviorally. I'm very excited for what is to come within the next decade or so. It would be so cool for humans to finally colonize Mars and discover new ways to travel through space faster.
Thanks for inspiring young people to get into Aerospace Engineering
can confirm that's what I'm doing
@@jacobknollinger4943 ditto!!
Dang, look at all these rocket surgeons in the comment section
Can also confirm,
Source: Am young and EA is probably 50% of the reason for my greatly accelerated interest in space and now I'm planning to go study space engineering.
yup, kids, any job in science and technology will beat standing on the corner with a cardboard sign!
Space x protecc
Space x attacc
But most importantly space x use steel so the rocket don't cracc
I love this comment on so many levels
doesn't***
@@lvintagenerd That don't fit the rhyme.
*protecc
*attacc
@@euibincho5213 *cracc
I’m super excited to see a shiny rocket! It’s going to look unbelievably sci-fi
Agree!
Finally we're getting the space ships that mid 19th century showed us. You can't beat that! I'm not a Apple guy but when they released iPhone it knocked the competitors design out the door. Functionally it doesn't matter how it looks but the feeling among the general public will be great. SpaceX might be igniting a great new support and interest for space travel.
... Our ludicrous future indeed...
@@subwarpspeed the best part will be watching it land on it's find like something right out of a comic
kikivoorburg . It’s not a coincidence that it looks like the 3 stooges scifi classic, Have Rocket Will Travel. Predictive programming at its finest.
Yeah, but where are Bugs Bunny and Marvin the Martian? ;-)
@@subwarpspeed 19th century? That would have been Jules Verne's giant cannon and bullet. I do believe the BFSs (I refuse to use Elon's stupid new names) should all be named after astronauts and science fiction writers, and the first one back to the Moon should be the SS Jules Verne.
Thanks. Very clear and interesting. I appreciate your efforts in educating yourself and then us on this topic.
same
stevenson720 this should be top comment no offense to WD-40 lol
Also remember the falcon spaceship has one of the widest spaceships diameters. Then remember the volume of a sphere increases with the cube of the radius. Because the falcon spaceship is so large it will probably have the lowest ratio of stainless steel to fuel for a given tank size. This should actually make the tank relatively lighter.
that is correct ^^
in this case size really does matter haha
But the sheet is thicker ^^
?? First, if you JUST made the tank larger, it would have more volume to surface, of course. But that gas NOTHING TO DO WITH the material. It applies whether using steel, carbon, or plasticine. But at the same time, volume equals mass, and mass means forces on tge walls of the tank. That means THICKER WALLS. So a larger tank, in the end, means a LOT more mass to lift per kg of fuel.
@@markdoldon8852 I see what you're saying, and it does seem like my initial thought needs more processing. I do wonder what the final trade-offs would be after you do all the math.
@@markdoldon8852 What is relevant for the material requirement is not absolute force, but pressure (force/area). From the fluid pressure depth equation, the pressure is determined entirely by the density of the fluid, and the height/depth of the tank. Absolute mass or weight of the fluid DOES NOT MATTER.
What does change the situation a tiny bit is the curvature of the sides. Since the radius grow, the walls need to have a greater degree of flatness. The curvature does change the ability of the material to support pressure. I looked it up in an engineering handbook that thickness of material need to grow with power 1 with increasing radius, for unchanged pressure.
BUT this is probably a really high estimate, since it's meant as a guideline for plumbing, which also need to support it's own gravity - suspended vertical cylinder shape instead of horizontal cylinder shape.
Anyway, from geometry alone the mass of steel sheet grows with power 1 from radius (O = 2*Pi*r), while the volume for unchanged height grow with power 2 from radius (A = Pi*r^2). Of cause a change in height will increase both the volume and pressure - so thicker material is needed.
But the role of the growing radius in all of this is that the wall mass to fuel mass ratio is a worst unchanged (for pessimist estimate of curvature factor), but for a realist estimate it will improve with increased radius of the cylinder.
Btw. I have a master of science degree in physics.
It's alright, sweat just means the rocket is making massive gains. I'm sure they'll make some rocket sweat bands for when it takes that payload to orbit with its massive biceps.
Explosive power
massive payload from the tip of a dildo shaped rocket. no way you could get the same payload from a vagina shaped rocket.
Lmao
A few really good reasons:
* Strength at cryogenic temperatures
* Characteristics at high temperatures
* Ease of development
* Price
and you forgot...
* Doc Brown's Delorean time machine was made of brushed aluminium
The delorean is made of stainless steel not aluminium
wat
@@givejamesacall this guy gets it
Just to confirm...AS everyone knows, Stainless steel it was.
@@AdventistTruth I ruined my own joke. I meant to say brushed stainless steel but I must have written the comment while he had that chart up comparing stainless, carbon and aluminium and I have written "aluminium" instead. Doc Brown's Delorean was the first thing I thought of when he started talking about the reasons for using stainless. D'oh!
"engineering is all about compromise" I wish I had more hands so I could give this 4 thumbs up. I'm going to save this little nugget for my next meeting!
Mother nature compromised, and that is why you only have two hands....
how'd the interview go?
60x cheaper material cost for the hull / chassi.
Dude. They might be able to afford TWO or THREE BFR's for the same price as ONE carbon composite BFR.
Hell yeah, i'd much rather have two/three chances of success, than one chance.
Elon constantly making intelligent changes to ensure the success of the mission.
well elon keeps contact with material sciences and manufacturies. so if they invent new materials or production methods, they know where to find their first customer for their product. also, producing steel used to build high tech space ships is a better marketing strategy than producing steel to make forks :)
Most importantly 3 BFR's could travel all at once and provide some degree of assist to each other should something go wrong in fligh or on mars.
"It just works"
- Elon Musk
-Steve Jobs
He told the same about carbon. Then they made some naive attempt to make a 12m tank of carbon fiber in the back yard and failed. And now they are telling what a wonderful stuff stainless steel is.. didn't know about it before ?
Little lies, stunning shows, people buy, money flows! It just works, it just works, overpriced open worlds, people buy, money flows, it just works. It just works. It just woooorks.
Here is an idea that could work, and save weight. Cool the skin by exploiting the slower-moving air molecules that flow near the surface of the re-entering craft. How? By having slits between 'steps' that faster-moving molecules skip past, but slower ones can enter. This cooler air would be somewhat pressurized, and could be funneled under the craft's skin, and out small holes that are pointed in the same direction as the airflow around the craft. These exit holes would experience almost no pressure, because they would have small grooves in the craft's skin down-wind from them. Maybe use some methane at the higher pressure areas since not much pressure (but more than elsewhere) is required to eject it.
@@FLPhotoCatcher Maxwell's Daemon could help here.. Just need to improve it so he(the Daemon) could work in the high hypersonic flow.
No market for 100 ton payloads??
You got that backwards buddy, when the current launch vehicle limit is a couple of tons then every satellite is a couple of tons by default.Create a delivery system for 100 ton payloads and people will design bigger better satellites to launch on it. No need to miniaturize anything anymore, no more exotic light alloys. It will be cheaper to build a heavy satellite and cheaper to launch on a re-usable rocket.
Yeah, I can imagine some future engineering discussions in startups: 'You say a rad-hardened board certified for 15 years costs how much? ...How about we just encase a few redundant standard PC boards under a meter of high density plastic, do we still fit on the shroud?'
Better yet for space stations.
ummm, Space debris?
@@guillaumehumbert4545 Cheap satellites have a relatively short lifespan, after which they deorbit and burn up in the atmosphere. Low-Earth orbit is self-cleaning.
Satellites are getting smaller and lighter every day. There could be a market, but it will be pretty small. Only real reason is Mars.
What I like best about the major shift from carbon fiber to stainless steel is that it's a reflection of Elon's and SpaceX's willingness to think way outside the box all along the project lifecycle. Most large engineering projects are averse to this agility, turning a blind eye to their discoveries along the way, and sticking to early bad approaches. SpaceX is willing to adopt new technologies without missing a beat - and that says more about the culture of the company than about anything else.
Being innovative by replicating solutions developed half a century ago, umm yep, okay. Get off your knees boy.
@@Veldtian1 Everything is a remix boy. Innovation is not invention.
@Angelo Stevens I think because the old tech is now mostly dismissed. Sort of like what Elon did with Teslas. Sure there was proven sound science in that area (albeit definitely more controversial), but no one was utilizing it. The same goes for this occasion. Old and underutilized, but still good; so let's remix it. This is like the space/ rocket version of electro-jazz (or w/e the kids are calling it these days): new and old, all at the same time; and better for it.
@Angelo Stevens Sorry for the wording. I meant the science behind the 'engine' in Tesla cars wasn't being utilized. Steel (in reference to use in outer space) is the 'underutilized' thing... As far as I knew, the engines in Teslas hadn't really been put in to actual effect anywhere. I was under the impression other electric cars used a similar but different engine... I'll look it up tho. ✌
Edit: the bad grammar was killing me, sorry
In this case, they are not afraid to use an old technology that works for their use case, which indicates they are goal and not image driven. A win win in my book.
Sometimes, things just continue to be the right thing. In our push towards progress, we have to be sensitive to that, otherwise we will pass up a perfectly good opportunity in favor of something more 'sexy' that, while really nifty, isn't the right thing and will end us up in a failure mode.
Learn from the Shuttle folks. Arbitrarily expensive methods are not necessarily the best solutions.
Wow thanks man that really helps a lot to get a more clear picture of why stainless steel is planned to be used.
@ryan cairns Why not? The Atlas "flew" (that's not really the right term) through space, and it was made of stainless steel.
When the guy touched the foam at 7:43 I nearly had a heart attack
I think it was technically a female technician, but it's kinda nifty that 'guy' just sorta means the same thing as 'nerd'. : )
@@keithkelley7380 guy can be a general term for a person when you don’t know the gender
"Sweaty Shiny Starship" - Retro Sci Fi Writers.
Just like propulsive landing.
Heck yeAh
Maybe those guys in the 1950s were able to predict the future well after all
If I remember right, WD40 wasn't used on the Atlas rocket to prevent rust, since stainless steel is already resistant to rust. It was used to prevent a build up of ice formed from condensation on the outside of the rocket. WD stands for "Water Displacement", btw.
Elon is making the past happen.
@@MegaZsolti Back to the Future!!!
Another advantage of steel is fatigue life. As long as you keep the material within the regime of elastic deformation and stay out of plastic deformation (ie do not exceed the yield strength), fatigue life is indefinite. This isn't the case with aluminium alloys - it's why airframes have an "hours limit". For expendable rockets this isn't really an issue, but for a reusable system it will become one.
That depends on the crystal structure of the steel. BCC steels have indefinite fatigue life, but FCC steels like 304 and 310 are susceptible to fatigue just like aluminium alloys.
This is because dislocations in FCC metals are more resistant to temperature, whereas dislocations in BCC metals are more resistant to oscillating stress.
Metallurgy student here. At 6:20, just a small correction, cold forming by default is not done at "cryogenic temperatures", it is done near room temperature. The name comes by comparison to the temperatures used during other mechanical forming processes. Not sure about that Elon Musk's tweet about it...
Correct about the common definition, by default. But Tim (and Elon) was referring to a specific new cryogenic process, apparently a quite recent development.
Had meant to correct this. More than likely I am wrong and Rui is correct. What Elon said is a bit unclear - most likely meant that cold-formed (rom temperature) steel has properties that are good at cryogenic temperatures. But I can't say for sure.
j mcmann he’s already gone to space, so you’re clearly not up to date.
@j mcmann The falcon 9 was developed for around $400M and is reusable. You can say neither for any other rocket program that has ever gone into orbit.
@j mcmann seems to be all we got for now, what's your idea?
I love they got space ships spot on in the 1950's.
Yeah, back when science fiction was based on science, not on imagination.
Most importantly, it gives Elon the opportunity to suggest that his critics, “kiss my shiny metal… spaceship!”
favorite reference
More like, "kiss my shiny, sweaty, metal....spaceship."
BUY NICKEL STOCKS, LOL
Yeah, as youre all kissing every union-busting CEO cock, that sure is the look to go :D
Love the JavaRush references
Sweaty metal -- reminds me of the Polaris missile nozzle. My father in law was a rocket engineer on that project and showed me a nozzle he came up with which used a sintered first metal (titanium?) filled with a second metal (?don't remember what metal). The nozzle cooled itself by sweating off this second metal as it went providing sufficient cooling for its entire burn duration. He was also involved with rockets on some of the space missions. My Dad worked on projects for the Air Force, and was back at the Cape control room for a few of the Apollo launches . He brought back lots of cool materials for me -- I was really in love with this stuff. PS -- I ended up designing electronics - not as sexy - but it was more economically stable - LOL.
I was a guest at the rollout of the Roton. We got a fairly up close look at the test vehicle and it was definitely a 'novel' design. Actually 'bloody stupid' was what most people called it. But the buffet was good. BTW I never knew I had an ICMB mission critical component under my sink! This was a great episode Tim, one of your best.
Stainless Steel Is Underrated
Super, steel metallurgy has come a long way
69 likes
100 tons to LEO might sound crazy now but there's a well known principle of "you build it and they'll come"
There's not much market for it now but there wasn't a market for digitally distributed media before someone made that an option either.
And not to mention, it looks absolutely awesome.
That is highly subjective. I think it looks hilariously stupid. But if it works I am all for it :D
@Guero Rodriguez replied to the wrong comment? 😅
Shiny '50s rocketship, hell yeah.
The 2016 and 2017 versions looked ALOT better.
The TNTsheep It should ,you helped pay for it!
SpaceX's leaky heat shield isn't a new idea and it's actually quite well proven. The SR71 Blackbird used to leak fuel out of it's leading edges to cool the aircraft at hyper sonic speeds. For a long time they claimed when asked about the leaking that it was an unintentional effect of how the plane was built and that the leaking would stop when the aircraft heated up in flight, but it has since come out this was a lie. In truth the fuel didn't ever stop leaking, it was actually an active heat shield that worked pretty much that same as SpaceX is planning for Starship.
THX 1138 not quite, it routed the fuel through the leading edges wing before sending it to the engine. It was also very special, and very expensive fuel. But it did actively cool the leading edges.
It famously did leak on takeoff, but that’s because it needed to heat up to seal the tanks.
Nonsense. Yes, the SR71 leaked constantly. That was not intentional. If they wanted just a leaking fluid, theyd have used something other than highly flammable jet fuel
@@markdoldon8852 JP7 fuel was specifically formulated for the SR-71 and was most certainly not highly flammable! That's why they needed to use TEB to start the engines!
It was the fuel tanks that leaked. Not the lines. It was because the aircraft needed to expand to seal them. They would take off with a light load of fuel, heat the aircraft up then refuel inflight to fill the tanks.
I know the aircraft grew in flight. You could boil a kettle on the tire after the flight. It was made out of titanium. (Which I think the CIA bought through a shell company) it was designed in the late 50’s. And it was really boring to fly. That’s why the pilots called it “the sled”
"Sweaty metal" - name of my new band
more like name of the genre I'm about to invent
You know what’s really cool? My physics teacher was the pilot on some of the Space Shuttle missions. It’s incredibly inspiring to learn from someone who was in space!
Luck-eee!
Fun side note: the Atlas Mercury rocket at the U.S. Space and Rocket Center has an air compressor that keeps it pressurized.
Don't often leave comments but this video is amazing. Do more rockets physics please!
A few comments here, after having a conversation with a metallurgist (who just so happens to be my father).
1. The cost of the stainless steel depends upon the alloy used (there are thousands - and they're all very very different), but you're still right - the carbon composite process and cost is prohibitively expensive and time-consuming.
2. Another interesting alloy that is what is used in stainless steel ball bearings, which are typically made from 440C (which is too brittle and can cause failure) were replaced with carburizing stainless steel 675 Stainless (a fascinating topic in itself that got addressed after the challenger disaster)
3. Testability for failure was left out. Carbon composites make detecting flaws (especially in a reusable rocket) a tricky business. When you are working with stainless, the techniques are well-established and test are not particularly expensive to run - which would be a consistent expectation before every new launch. It might be an interesting episode to talk about how certain materials can be tested for things like risk of failure - where small defects can be disastrous.
4. WD-40 will (probably) not be required, or anything like that. But we had a good laugh from the animation about the drones spraying the rocket down - that was pretty funny. 2 points for the space humor.
Steel has gotten way more modern, better benchmarks would be CPM S110V or Bohler M390. Theres many other "super steels" and I'm not sure what exactly they would be looking for, but those both make 440c and 675 look like rusted tinfoil. Mostly this has to do with modern manufacturing like particulate metallurgy and the advancement of metallurgy for specialist industries. The addition of elements like molybdenum, cobalt, niobium, and nitrogen have created a myriad of modern steels with different properties.
I love how SpaceX is giving the finger to everybody insisting on the most fancy and complex technology. It is good to see someone go opposite direction of the Space Shuttle craziness. As a fan of Soviet space stuff, I cannot help but see some similarity in philosophy. Both seem to value simple cheap solutions over fancy and expensive stuff.
Like the Soviets, SpaceX strapped on lots of small rocket engines, 27 of them on the Falcon Heavy. People used to say for years, that is why the Soviet N1 moon rocket could never fly. SpaceX proved the naysayers wrong and showed lots of small rocket engines work.
The Merlin Engine was basically a simple 1960s rocket engine. I like the novelty of taking an old design and using modern manufacturing techniques. It is sort of like designing a new car using T-ford technology, but building it using CAD/CAM, 3D printers and modern material science.
Now we got steel! I love it! People have been too into technology for the sake of technology, and forgotten about economics and practicality. Following SpaceX and reading up on Soviet space exploration is partly why I got into reading low tech magazine: www.lowtechmagazine.com . Highly recommend to anybody more curious about using smart low tech solutions to many everyday problems.
well its not that much of a middle finger if you have sunk a lot of money in the fancy stuff previously(composite at space x or the aluminuim chassis in the model 3 XD ). but yeah good to see. ill be looking up the magazine as well.
The tooling alone for a composite ship would cost them close to a billion dollars US and that doesn't include the cost of the materials for the ship itself nor does it include the cost of the autoclaves that would need to be larger in diameter than the parts getting cured. Big money burned quickly.
Its still always a good idea to research and explore these technologies. That is how they become cheaper. No hate towards SpaceX here though, I think this is one of the best idea's they've ever had!
Just don't forget that they still have and the stuff of/in the old command center (y'know, that stuff from the 60's/70's) because it's not as error prone as the new stuff.
Same with some "failsafe" Nuclear launch sites from the NAR.
@@Baconator119 Problem is Boeing and Airbus have most of the worlds production prepreg carbon fiber tied up building regular old plastic airplanes. The costs have come way down from when I first started building it where $150 to $190 US per 1 sheet 1' x 1', it cost us millions to build 1 tool for making carbon fiber aerospace parts.
Not sure if mentioned in the comments already, but another big advantage of stainless steel is scalability.
Building a 9 m carbon fibre rocket requires big mandrels and and curing techniques that are technically risky.. Going to a larger diameter is capex intensive (new mandrel, more technical risk with curing/delaminations, etc.)
Building a 9 m SS rocket is just welding stuff together..
If they can make it work, and the raptor is reliable enough, there's very little holding them back from making a far bigger rocket out of SS.
12 m? 15 m? 20 m? Same manufacturing process, more engines/plumbing, and of course more payload.
The comment about the space shuttle tiles soaking up a lot of heat and radiating it later (around 7:50 in the video) is not correct. Those tiles had an extremely high insulation value. That is the reason why they can be picked up with bear fingers. The material itself has actually taken on a very low amount of energy. When touched by fingers, the energy in the area of the contact points is so low that the skin quickly absorbs it. As the same time, the heat in the rest of the tile (which is still not very much) is so badly conducted, that it hardly flows to the contact areas. Hence: no burns.
Great explanation to a very misunderstood concept. I searched for this comment and am glad I've found it.
They could even be picked up by human fingers. ;)
@@IAmTheRealBill : Video showing that in action when tiles first introduced.
Ummmmmm, bears don't have fingers. 🙄
oh i think they actually do absorb alot of heat(extreme high temperatures for a long time). They do absorb less heat than stuff like metals though.
The reason why fingers aren't burnt when touching the tiles(the tiles being put in an oven until they were glowing hot, pretty sure those tiles absorbed alot of heat then) is because the tiles are really poor conductors of heat, meaning that heat is conducted from the tiles to your hand very slowly, and so your hand doesn't heat up as fast. For example, putting your hands on a piece of metal and a piece of wood, heat from your hand is conducted away into the metal faster than into the wood, which is why you feel metal is cold, wood is room temperature. Both at the same temperature, but one feels cold. Do that for the reverse, the tiles feel alright not because they have little heat but because they conduct heat slowly to your hand.
So the tiles do absorb alot of heat, just that they are poor conductors of heat that they conduct the heat slowly to your fingers.
Ok, so first of all, you're awesome. I discovered your channel yesterday and I love it.
I just want to mention a couple material properties that you missed. The first is that steel has amazing fatigue characteristics. They might not come into play in this specific use case, but it makes a huge difference in re-usability.
The second is the reflectivity thing. On re-entry, most of your heat is coming from friction, not radiation. This means that the shiny, reflective surface (low emissivity) won't make a big difference in how much heat gets absorbed. This does mean though that the surface can't dissipate it's heat well using radiation, because having a low emissivity means that you don't absorb much radiant heat, but you also can't dissipate much radiant heat. All of that said, I'd love it if you proved me wrong.
Cheers ;)
Comment on "There's no need for 100 tons to low earth orbit." (paraphrase, about 14:30).
Engineers don't design the size of bridges by counting the people swimming the river.
One reason ISS kept getting redesigned smaller and smaller is cuz Congress (or the WH) mandated all parts would go up on the shuttle. First plan was to launch a few really big pieces on disposables ("disintegrating totem poles"), then do all the rest with shuttle. That wasn't acceptable to the political leadership at the time.
If the capacity is there, it will be used.
@Aquarium Fuzz - I couldn't hope to put it better myself! I also say, that weight is one matter, SIZE is other. Booster of this size should be able to deploy telescopes with 8m unitary mirror, like ATLAST concept. Moreover, 100t to LEO is far less when GEO, Moon, Mars are concerned.
@@piotrd.4850 - it's kind of ironic that one of the most limited resources in space is ... space. An enclosed volume that can be used as a shirt-sleeve environment is hard to come by, because it most either be aerodynamic for launch thru atmosphere, or expandable once on orbit (see SpaceHab). Cavernous multi-room quarters for spacecraft personal (See Star Trek for examples) is such a laughable hollywood concept.
So shiny and so chrome. They need to shout at take off "Witness Me!"
Amos Suttelle WITNESS ME! (Actually Furiosa would be a cool rocket name too...)
Onto Walhalla!
WITNESS!
Elon seems to have implied funding BFR is something of a challenge. I imagine being able to make it happen for cheaper sooner is very good in their books when R&D for cutting edge rockets tend to be very prone to ballooning costs and timelines. SpaceX has always been about financial viability from their start, this is exactly their way of doing things. Don't do what is the craziest and highest tech, do what balances all the equations, including the money.
One word. Ares. Spend billions to make it only to scrap it.
Sucks that the human species is held back from great achievement by money. Wish i could give them an unlimited budget.
yes, old tech is constantly being "replaced" by new tech, but old tech patiently waits to be "re-discovered", especially when it's only 1/60 the cost!!
@@TheFailedmessiah A second word (well, acronym). SLS. At this point there's no chance we'll get more than about two launches out of it, for minimum $40 billion.
I instinctively knew or inferred some of the reasons why SpaceX moved from carbon composite construction to stainless steel, but you made it all crystal clear. Thank you for this presentation. You did a fine job.
Best video you did so far!
I love it and woul'd utterly enjoy more content like this. Luckily there is much going on right now in the space sector so there is tons to learn and talk about.
Has he done a video about Stratolaunch yet?
I actually considered content on this channel not worth my time, because alot of "101 basic stuff", and repeat what i already know from other sources just reasoned more easy. But this actually gave more of the technology part described for dummies. But still enjoyable for giving insight in the technology they are going to use/technological challenges they had to overcome.i'm not a technoguru, but he also does target the average joe so i don't blame him. Thanks for the update.
I'm so glad he toned down the shrill, hyper, style he used to do. Still was expecting a very basic overvew, instead got a well researched and well reasoned analysis. Good job.
Agree. He is likeable so I'm subbed 😃
True and not many years ago it was just dead. Now it's full on and growing!
SpaceX engineer: Alright Elon, cool idea with BFR, but there's no way we can belly flop this thing without cooking everyone.
Elon: What if we just set the belly on fire?
Added bonus: If it is used in an oxygen-rich atmosphere, the fuel would actually combust and expand, which would give a small amount of extra "drag".
With some smart mechanisms on the fuel flow this could even be employed as RCS on re-entry to provide attitude control.
No, elon went cooking....that gives me an idea, cooking pots...how about stainless steel
@@technotoaster you mean ,,ah...this is exactly how that happaned .th-cam.com/video/XpE8e6AYmfo/w-d-xo.html
@@Stoney3K seriously though, re-entry temperatures are so hot that "combustion" kinda stops being a thing, as everything's a plasma. By the time it stops being that, it's well behind the rocket, in the re-entry trail.
@@kargaroc386 That means it doesn't react with the oxygen in the air during re-entry? After all, a flame is a plasma just as a re-entry shockwave would be.
The contribution it would have to additional drag would probably be questionable though.
Let's not forget the ease of repair! You have to consider the fact that these ships are going to fly to some rough and remote places. If carbon composites break or create a fracture, it's very difficult, if not impossible, to repair. With stainless steel, however, you can just weld it on the spot.
On the other hand, composites have a structure that resists propagation of cracks, whereas metals tend to do the Comet thing: rip like crazy. I'm not sure what they intend to do about this sort of thing with stainless...
Boy, wouldn't it have been nice to do that on Columbia.
@@AttilaAsztalos Metals typically used in aerospace like aluminium have bad fatigue characteristics you are right, and eventually just fall apart as cracks propagate through their structure. Steel is much more better in this respect and has a fatigue limit of about 1/3 of its nominal strength if remember my old engineering course correctly... That means that after a lot of load cycles the actual strength of steel tends to 1/3 of its original value. So if you design your structure to withstand at least 3 times the expected load you should be safe from fatigue issues, albeit with a weight penalty...
Coming back to this video after the first orbital launch attempt.. we got to witness how strong starship is… amazing
I just showed your video to my physics class. That's why I love your channel. You keep it clean so I can show it to students. Also... Elon replied to one of my tweets which was a reply to one of your tweets. I can die happy now.
Tory Bruno replied to one of my Reddit comments. I think that's as close as I'll ever get
@@SuperSMT I showed Tory some KSP creations and he loved them.
What an incredible video. This has to be your best yet. Great presentation of your extensive research, great reasoning behind everything you armchair engineered. Really impressive stuff and most of all super entertaining!
rausch101 well said, I agree
100% agree. I greatly appreciate the effort.
Lol, except Scott Manley has already did this and probably where he got his ideas.
@@JJayzX Scott is a great TH-camr who offers a somewhat more technical perspective. Tim is the everyday astronaut because he wants to explain it to everyday people. So what if Tim watched Scott's video? He wants to make it easy for people with 0 technical background to understand. He wants to introduce space to a new audience.
@@mrcon012 I have a technical background, I actually used to be an astronautical engineer, and I like them both.
Good job, Tim. Interesting, clear concise and informative. Just as always. Thank you.
1950s Retro is GOOD THING! Duck Dodgers in the 24½th Century!
Always been a little proud. My uncle actually helped design those ceramic heat tiles on the space shuttle. Vital to reentry and keeping our men and women safe while landing. :P
OMG the WD-40 Drone graphic was precious!
If I remember right, WD40 wasn't used on the Atlas rocket to prevent rust, since stainless steel is already resistant to rust. It was used to prevent a build up of ice formed from condensation on the outside of the rocket, so the application of drones for the application still applies! ...WD stands for "Water Displacement", btw.
@@sparky6086 yes water disp. formulation 40. the animation is still precious.
@@matthewschrader4494 It wasn't a graphic it was real..... Ok I have a good imagination.
@@matthewschrader4494 I agree!
I love this video! I am a big fan of using steel when it makes sense. Being a hobby custom bicycle frame builder, I have found that carbon fiber composites are commonly used as a buzz word material to sell products for higher prices. Who needs carbon gear shifts and dashboards, except for bragging? Carbon is commonly wrapped over cheaper materials such as aluminum to fool the consumer. "Steel is real".
Yup... once all factors are taken into account, Steel can be really hard to beat even when weight is a consideration. Stiffness matters a lot, and increasingly, so does "printability", and strength when printed. Stainless actually gains strength when it is printed, as does certain grades of Titanium,and for items that are going to be re-used over and over again, fatigue strength also matters, and also favors using steel over less dense materials.
@@63turbo That's an interesting point - being able to print replacement parts is incredibly useful. If we are going to the Moon and Mars a delicate system that kills everyone if it gets slightly damaged (during re-entry say) is not good enough. But with a steel ship and printed steel parts you can do running repairs which has to be a very good thing!
Absolutely!
People definitely get hyped about carbon everything, saw it first hand building carbon drag car bodies. But I'd rather have a carbon fiber surfboard than a stainless steel or aluminum. Sometimes you just can't compete with very light weights.
Well, as I'm sure you know as a bicycle frame builder, carbon fiber is significantly lighter and has a much higher strength to weight ratio than steel. It may be a "buzz word material", and most people that use bikes probably don't need it, but it is empirically superior to steel in the vast majority of use cases. I suspect you don't like carbon because you build bikes out of metals like aluminum, and carbon fiber demand is cutting away your customer base, but please don't act as if it is snake oil that "fools" the consumer when it is actually a superior material.
You know what they say, you can have it fast, cheap, or good quality. Pick Two.
elon : yes
Try to tell that to all of the Socialist leaning idiots in this country....
Sometimes it's pick one.
About the same payload capacity as the Saturn-V is a good number. Energia is close, and the Shuttle stack does this too, but less of it is useful payload.
There are innumerable potential near-term applications for ~100 tons to LEO. And it's smaller than we should be pushing rocket design for. Sea Dragon was to be simple steel 2STO for ~500 tons to LEO.
There were lots of post-Apollo "Nova" and some during the studies about SSPS systems for which ~300 tons might have been the starting point for 1 or 2 STO designs.
Rockwell Star-Raker SSTO plane was for 100 tons, in a standard cargoplane or flat-bed sized load arrangement.
There were never any severe technical problems about these. As with the Saturn-V and NERVA engines, they represented an embarrassing excess of capability to an agency and government which had no ambitions post-Apollo at all.
That's not the way space must always be treated. Musk is proving that to be so. We've been artificially held back despite ample public support for a real space program. We're used to thinking small and having no lasting funding. We were made used to treating space like that.
Thanks for another great video. It seems odd that anyone would criticize SpaceX for solving the problems that it needs to in order to make this rocket a reality. When the first one orbits the moon or lands on Mars will that accomplishment be lessened by what it is made out of? I’m on team make it happen. Build it out of adobe if that is what it takes.
At first I read this as "adobo" as in "adobo peppers," and thought that was odd, and then realized it said "adobe," but then I thought about Starship being built out of Adobe Photoshop, and then I finally realized what you meant.
I need an adobe ship in my life.
@@fr3nchy226 I was going to share the SNL Adobe car commercial with you in reply but I could not find it :-)
When or if?
@@aristeidislykas7163 SpaceX has better odds getting that rocket into space than I do :-)
Adobe: en.wikipedia.org/wiki/Adobe ?
I like how you stretched the photo of Starhopper to make it 16:9 : )
I heard this from an engineer recently: "every real expert for plastic uses steel"
For plastic? Wdym
@Maxwell Adams
We hear a lot about how many cool new materials are invented, a few years back everyone was hyping carbon fiber for example, lastly I heard much about graphen getting popular (which has even less industrial use), but you hear much less about how much we can actually do with steel. Then people are surprised that Elon uses good old stainless steel. Since all the stuff his innovative companies build seems so futuristic, we generally expect them to create and use some cool new carbon fiber or composit materials, but no. STEEL.
To those who works with and know materials that Was no real surprise, that's what I meant.
Steel in general doesn't have many special qualities, compared to some materials out there, but it has by far the widest range of application. Good for us, it also happens to be made of the most common elements
It would actually be pretty space-x ish idea to spray Wd-40 with drones....
Come again now?
That's what I thought I was thinking
"Hmm he probably would"
WD on everything! I now have it on my toast!
well if that's 60 times cheaper, then I'm eaging to see a fleet of 60ish starships heading to Mars!!
Can you imagine us not sending not 1, or 2, but 10+ ships to Mars on the first attempt? If something goes wrong, it would be much easier to fix it if 2 ships could meet mid journey. Imagine if 1 ships was used as a fuel tanker. Think of the possibilities. If all else fails, and a ships has to be abandoned, a crew might be able to perform extremely risky and dangerous ways to get into another ship. Backups of backups, just in case.
@@johnathangoodwin3610 A fleet, I like it. Just like in the great movie "The Martian Chronicles" starring Rock Hudson. Hey, they were shiny rockets too!!!
@@johnathangoodwin3610 Elons favorite word: "abundance"
@antiamii made up that word...eager, i wanted to say eager
@@taxximaxxi It's all good! A "normal" YT phenomena; we all make up or misuse words here,...…. or should I say hear! LOL. :D
Great content Tim - I think, as a credit to your content, the people who complain about “too much Kerbal” simply wish every video of yours was like this - although of course it’s impossible to churn it out all the time ;) they should just filter themselves. This is epic stuff though - everyone agrees.
His eyes have different colors! And hes good with space stuff... Hes definitely an alien.
i didnt even notice that..
Anyone see the movie "The man who feel to Earth."
His eyes look to have the same color to me. Plus, ever heard of Heterochromia? Look it up lol
There is just more light from the left.
If spacex succeeds and BFR becomes a game changer in terms of how cheaply you can put suff in space, why not use that lift capability to assemble a BFR carrier, a spaceship designed for interplanetary travel only (no landing) and then land multiple BFRs on Mars at once?
Exactly, a large transport that has rotating sections to simulate gravity, reducing bone/muscle loss while in low/micro gravity environments.
When the colonisation will trully start over that kind of station will be nessesery
@@MarkLLawrence I built exactly that a few days ago in KSP. With reusable interplanetary ships it just makes sense to not let them land but keep them in orbit at all times.
Just merge the spaceship and the rocket together to make a big SSTO spaceship.
@@johntheux9238 you don't want to haul launch hardware all the way to other planets as it is useless weight
"Conan, what is best in life?"
"Stainless steel, balloon tanks, and WD-40!"
Don't forget the Lamentations of ULA.
That is good!
@@MarkLLawrence No, no, the lamentations of Russia!
The SR-71 was another wet aircraft but not for cooling or defrosting purposes. When the plane got up to speed in flight, the increased friction with the air would cause it to heat up and the metal to expand. The fuel tank was intentionally designed to have gaps that would leak but would then seal together once in flight due to expansion
I love the Blackbird! Lockheed planes rock!
@@ginnyjollykidd Then again... Lockheed also made the F-35
@@AcButeo the F-35 is a good plane, but continuous changes in the requirements made the development expensive. Yet today, it is cheaper than some 4th gen aircrafts.
SR-71 used fuel to cool the skin and other systems
It became more fuel efficient the faster it went
Rewatching this 2 and a half years later, after Tim's excellent 3 part interview with Elon at Starbase, August 2021...so much has changed, but not the core mission and it shows in all the right ways.
MuskCult
if its loose and it should be stuck, use duct tape.
If its stuck and it should be loose, use WD40
I think the stainless steel design is more like an engineering miracle than the carbon fiber version was turning out to be. SpaceX is famous for getting more bang for the buck. The stainless steel design does that.
The people that created Buck Rogers back in the day got the design right!
Nice Thinline Tele in the background!
Great guitar! Watch that capo being left on though! I had a Eric Johnson Strat with a maple neck like that and I left my capo on one day and it left a dark line I could never get out of the finish! Just a heads up! Love ya man!
@@coynerooski Eye for detail. I like it.
except its going to be warped from laying it against a wall
I looked in comments to say the same, I'd love one of those things (a '69 model though rather than the '72) but leaving the capo on and leaning it at a steep angle on a wall is criminal!!! (I used to be a live soundmixer and sometimes helped the roadies out when we were busy and that would be a sacking offence.)
The RS25 engine used a transpiration cooled faceplate for the injectors made from sintered stainless steel Rigimesh as well. Transpiration cooling is not new either.
Another advantage of stainless steel: just add a flux capacitor, and you've got a time machine. It'll definitely go 88mph.
To go to prehistoric space, destroy the asteroïd and save the dinosaurs?
John theux no, to go into the future. Find the one that is going to slip in undetected and wipe out life on earth. You then can use computers to determine based on its future trajectory where it is today and send a mission to annihilate it while it is far enough away to not present any danger.
I'm glad to hear of a rentry shield method distinctly different than space-shuttle tiles.
I'm guessing that because the rocket lab rockets are so small that they are a lot easier to make out of carbon composites.
I lost it when the $3 popped up idk why lol
Dude, your videos are super dedicated and complete, thanks for all the info, pics and graphics explaining all of these rocket science
Hi, Tim.
There's one thing that's been bugging me since the steel starship was presented, with the support that steel resists better to heating and thus needs less protection (less weight in heat-shield)...
It's that, even though a steel frame resists better to the heating, it will still heat up more, specially if there is not as much heat-shielding. What about all that is inside this baking-hot spaceship, like instruments, life-support systems and ultimately, crew and passengers?
In a spacecraft made of aluminium or carbon composites, the thermal ceiling will be at about 300°C, and needs a sturdy heatshield, to avoid damaging the frame and the interior. Well, if a steel frame allows the thermal ceiling to be raised to 800°C or more, that's still much below the plasma-creating temperatures of the surrounding air during re-entry - so, a heat-shield should still be necessary.
This begs two questions: 1st - won't methane cooling of the heatshield heat up the methane to unstable temperatures and expand it drastically due to heating, thus loosing it's thermal conductivity and cooling ability of the heat-shield?
2nd - won't it be difficult to manage overheating of the frame if it's allowed to heat up to 800 degrees or more, mainly because the interior must always be at or below 25 degrees?
Thanks in advance for your time.
Thanks Tim! I've been following SpaceX closely and thought I understood the new system pretty well. You still offered some good insights that I didn't know about such as the cold forming and the sweating metal.
Cold forming is so rad. You did a great job in summarizing it and getting my mind ticking
Now SpaceX finally has an excuse to polish their rocket lol
I remember having to wash down an entire SR-71 when I came in drunk, so the punishment for someone who screws up at Space-X will be to polish the rocket ;)
Now you know why WD-40 is involved! Get a grip man!
I like it even more with active heatshield, its more robust, eazy to repair (in space), and more reusable (nothing is oblative (engine or heatshield))!
Its called a "weeping wing" on the DA42 light twin. And it lets small aircraft finally gain anti ice capability at a low cost. Normally light aircraft pilots had not ice protection at all. So it seems to be a very functional very affordable plan.
Excellent video, full of solid facts. 10:05 This "sweaty spacecraft" idea is not new. I read about it around 1962, probably in the magazine "Flight", when various re-entry schemes were being considered. It is very reassuring to see Space X taking advantage of the entire canon of space knowledge and experience, something young scientists in other areas are often not doing in their fields.
Just because it's old doesn't mean it's stupid or useless
You've been teasing this video forever! I've been waiting with baited breath and you didn't disappoint!
By the way, the correct expression is "bated breath." The more you know!
@SB Husky But he baited my breath, like baiting a bear, except instead of dogs it was with promises of sweet sweet knowledge.
Props to you for using International Units during your video explanation.
Stainless steel is much cheaper than carbon fiber on a per kilogram basis, HOWEVER you require a greater weight of stainless steel to replace the same containment strength as the much lighter carbon fiber - and stainless steel also increases the weight of the vehicle. So your $180/kg versus $3/kg comparison is highly misleading without accounting for these two factors.
As Tim explained in the video, in mission conditions the actual strength to weight ratios do not differ that much. At the end of the day, the given concept might only work with stainless steel, while another one would work best with carbon fiber, which makes comparing costs somewhat complicated. However, Tim was clear about only comparing the manufacturing costs and at this point he is right without any question. All the best, Joe
I guess it still gives an impression
totally agree. you're devoting a lot more of your fuel just to lifting the ship itself. Also, I don't really get the price argument when talking about a reusable vehicle. I really doubt price was a factor in this decision.
@@xordus Hi Matt,
weight is actually a pretty complex issue. On the one hand, it depends on the strength to weight ratio, which is according to Tim similar for carbon fiber compounds and the used stainless steel in operational conditions (I haven't checked that myself, however). On the other hand, the designs in which CFCs would be used and those in which stainless steel would be used differ significantly. For instance, CFC designs would need to include an extra ceramic heat shielding, while this can be avoided and hence mass saved by using active cooling in a design utilizing stainless steel. Therefore, the overall mass of the vehicle more depends on how well the fine-tune between chosen design and used materials is, rather than materials alone.
I agree that the lower cost of stainless steel compared to CFC was probably not the main reason for choosing the first. However, SpaceX was and still is very consistent in its approach to avoid unnecessary cost and built everything as cheap as possible in order to create a larger market for their services. Hence, it does not come as a surprise to me that material costs are a point of concern for them.
Thanks, Joe
@@xordus Well even it's reusable if the vehicle is three times cheaper to make then you could have 3 starships for the price of 1 so more launched which equals more money.
Correction @ 6:27 - cold forming is simply done at room temperature as apposed to a malleable state when red hot ! hence the term 'cold forming' - its not to do with cryogenic temperature
The term cold forming as you mean it applies to a lot of materials/uses. Tim was referring to a specific type, specialty cryogenic cold forming. But he should have made this clear.
@@donjones4719 okay thanks for the Clarification. I was basing my assumption off my materials course I did in electrical engineering 😂
your assumption is accurate and it does indeed apply to sheet metal. square tube & other parts are often much easier to shape while hot, but there are reasons that it's reasonable to choose to do it at room temperature, in which case it's called cold forming.
@@JustinCrediblename Nice, thanks, I suppose room temp is "cold" compared to the molten state of metals! :D
Aircraft have had that leading edge deicing capability for decades and it's called a weeping wing system. A mix of innovative technologies and proven engineering is a good way to move forward!
Best BFR vid on youtube. Effin' well done EA!!!
Many people tend to think that "new materials = better, cheaper, hightech", but old materials aren't outdated as they may think. The wood, bamboo, steel and even bones keep getting new hightech uses where they literally outmatch the new materials. :)
Great video, great presentation, I like that new closeup format, thanks for the research !!
Wouldn’t it discolor after heating like a motorcycle tail pipe.
Rainbow color...
Won’t look so shine after first flight.
Dark Guardian still cool though
It will look so cool
Yeah, I wonder about this - and it's not just the looks. If discolored by Mars aerobraking, would it not have enough shiny radiative heat property for Earth aerobraking.
Look at those nozzles on the rocket engines. They are iced over with all that heat blasting on them. They will probably keep the stainless steel cool enough that it will prevent discoloration.
It will look even cooler IMO. And it won't affect radiative heating protection property since it's mostly infrared you need to reflect. The rainbow discoloration only affects visible light range
You shall ride eternal, shiny and chrome!
*Rocket immediately falls over - AAH! MEDIOCRE!
@@soupdujour4086 WITNESS!
Hey Tim! I'm wondering as we're heading to the first almost-orbital launch of a Starship combo. Is the sweating stuff still planned? And do we know if they will use the refregerative cooling for this test (sn20) or later and just stick to the tiles for this first try?
I'm not sure Elon meant coldforming AT cryo. At least that's not something I've ever heard of before. I think it was meant as normal coldforming of steel sheets which just means forming the metal at temperatures below recrystallization temps.
The forming of the metal increases the amounts of dislocations inside the lattice structure. Dislocations hinder the movement of atoms along the lattice structure which in effect increases the strength of the material. If the metal was over recrystallization temperature, the dislocations would disappear as the crystal reforms.
So the problem with cold forming is that the metal gets harder and harder and thus harder to form, especially if you have to apply stress over a long roller. I guess that is what Dawson engineered and can handle now.
The cryogenic part I think is referring to cryogenic hardening. So after hardening you cool the metal to cryogenic temperatures. This helps transform rests of austenite to martensite and furthermore creates a high density of gaps in the lattice structure which can be filled with special carbides that form during a subsequent tempering process. This further increases strength even beyond martensite. This is a fairly new technique and I'm not sure it has been done to parts as big as rocket fuselages yet.
I actually think using steel or even aluminium is a smarter choice for reusable rockets. Unlike metals, carbon composite parts fail catastrophically without a lot of forewarning since they do not really deform before breaking. They just get not visible micro fractures and suddenly they fail. Metals on the other hand will deform first which gives them a little bit of extra time to work and hopefully fix before a part breaks. So if a rocket lands an inspection should relatively easily find parts that are about to fail and can be replaced preemptively.
Disclaimer: That said I'm not a metallurgist either. So my knowledge is limited to the material science class I took during studying engineering at university, which was not my personal focus.
I thought that's what the new development is, cold forming at those extreme low temps
He specifically said it's a brand new manufacturing technique. It's not just cold rolling / cold forming, since that's definitely not new.
Actually, there *has* been cryogenic rolling, forming and treatment for over a decade... it is only recently that the process and uses are coming more mainstream. It has very specific applications and for a long time was very low volume... but uses have caught up with the tech as prices have slowly dropped... I worked at a plant that did exactly that for one quarter out of the year for certain customers.
@@edwardpaulsen1074 Indeed, cryoforming of austenitic SS dates back to the 1970s at least. Despite our modern association with "cryo", it means temperatures below ambient, so not necessarily super-cold by our modern us of "cryo", but also much colder than most of us would call "sub-ambient". IIRC, and I may not, you only need in the -150 to -200 degree Celsius range for austenitic SS to hit the optimum deformation needed.
Once you hit the deformation temperature range the type of strengthening is dependent on the type of stress you apply. Also I seem to recall something about the metal getting even stronger after "aging" - which meant getting heated up "above ambient" not just let lie around. If memory serves 304 specifically was noted to have strengthened further after being heated up to a few hundred degrees.
Again, take the above with some grains of ambient temperature NaCl, as my memory may be off a bit here and there on the finer points.