Starbase Tour with Everyday Astronaut — Part 1
Questions on ElonsFAQ asked in this interview (2)
Transcript
0:00Tim DoddHi, it's me, Tim Dodd, the everyday astronaut. Welcome to Starbase Texas. This is where SpaceX is building, testing and even launching their Mars bound rocket Starship. Today I'm going to take you inside the gates and show you things that have never been shared outside of SpaceX.
0:15Tim DoddBest of all, we have the ultimate tour guide, Elon Musk, who answers all of my questions and gives us unbelievable insights to the rocket's development. We talked and walked around for over two hours.
0:27Tim DoddSo I'll be cutting this up into three parts. The first two are at the Starbase factory and the last one is at the launch pad. Each section has a gold mine of valuable information, so make sure you're subscribed, you've got your notifications on, and you've got your notepads ready to jot some notes.
0:45Tim DoddNow, heads up. We talk about some pretty advanced concepts and subject matter that can be pretty intimidating on first listen, but don't worry, I've got you covered with lots of informational videos here on my channel.
0:56Tim DoddSo perhaps if you're new to Starship or really all of this stuff, consider watching my complete guide to Starship. That'll be a really good overview for you for some of the things that we talk about here in this conversation.
1:07Tim DoddAnd I'll also be linking to some of my other videos that will help out with some of the stuff that we talk about as well. Now you might notice we mentioned Soviet rocket engines quite a bit in this conversation.
1:17Tim DoddMaybe it's because I was wearing my new Soyuz shirt that you can [email protected] shop. Or perhaps it's because I've been working on a complete history and family tree of Soviet rocket engines for almost two years now and that video is currently in the works and it will be out when it's done.
1:34Tim DoddAnd one last thing, this video is broken up into sections and we have links in the description for those sections. We also will occasionally be putting up a little map courtesy of ring watchers on Twitter that will help you keep your bearings as we're walking around.
1:48Tim DoddI think that'll help quite a bit. And we also have an article version of kind of our conversation. Some of the key points that we bring up [email protected] there is a link in the description to that as well.
1:59Tim DoddOkay, enough talking. Let's go hang out with Elon.
2:02Elon MuskSo the camera with a camera and then somebody else with a camera.
2:06Tim DoddIt's just camera envy at this point. He's just trying to. He saw me with this and he's
2:10Elon Musklike, listen, I'll get my camera out.
2:11Tim DoddYeah, yeah. You take a video of me.
2:13Elon MuskI can take a video of this, of you guys taking a video over.
2:16Tim DoddMake sure this is going through there. Just shoot the screen the whole time. I don't want anything else.
2:22Elon MuskAll right, so this. This is. Okay, so this is. I'm being videoed here. And then the video of the video. And then this is the video of the video of the video.
2:30Tim DoddGo back.
2:39Elon MuskOkay.
2:45Tim DoddSo I feel like I got here maybe at about the most exciting peak
2:48Elon Muskof insanity, definitely a very exciting time, because we are in a kind of a final push to complete the launch system stage zero, essentially. And it's worth saying that the launch system, the tower, and the, you know, the chopstick comes to catch the rocket
3:08Tim Doddare
3:11Elon Muskas complex as either of the stages.
3:14Tim DoddReally?
3:14Elon MuskYeah, absolutely. If not more so, like, we could produce boosters and ships way easier than we could make to launch site. So therefore, I'd say it is harder, certainly than any single booster or ship.
3:37Elon MuskYeah.
3:38Tim DoddI think that's one of the things people don't even realize is the manufacturing out here. That's kind of one of those things that you harp on so much, is how you know, how that's so important.
3:46Tim DoddAnd that's in the long scheme, the hardest part of all this. It's just manufacturing.
3:50Elon MuskGenerally, manufacturing is underrated, and design is overrated. So people generally think that, like this. Like this eureka moment of, like, you come up with this idea, and that's it.
4:03Elon MuskNow it's good. But the design like this, literally 1,000%, maybe 10,000% more work that goes into the production system than the thing itself. So say, like, how much effort have we put into, say, designing Raptor versus designing the manufacturing system?
4:24Elon MuskIt's 10 to 100 times more effort to design the manufacturing system than the engine.
4:30Tim DoddEven of Raptor.
4:31Elon MuskOh, yeah. Especially with Raptor. So all of our basically quad. Basically, the amount of effort that goes into the design rounds down to zero.
4:45Tim DoddRight, right.
4:46Elon MuskRelative to the amount of effort that goes into the manufacturing system. And if this was not true, great. I'd like a thousand Raptors, please. Oh, you can't make them.
4:55Elon MuskOh, okay.
4:56Tim DoddRight, right.
4:57Elon MuskSo this is, like, just very fundamentally underappreciated. If people have not been in manufacturing, especially manufacturing of something that's relatively new, then they don't understand and they think the design is the hard part.
5:12Elon MuskAnd they think production is like a copier or something like that. This is completely false.
5:18Tim DoddWell, it's definitely not as sexy as the end thing, like, you know, the end product is very sexy and you know, that's what draws people's attention. But the whole back end of it is what makes it possible.
5:28Elon MuskI can't emphasize enough, I'm trying to correct the misperception that design is the hard part. It is not the hard part. There have been lots of great rocket engines designed.
5:37Elon MuskYou've spent a lot of time looking at the Russian rocket engine designs. Amazing Russian rocket engine science. They've been doing stage combustion for a long time and have done, I don't know, hundreds of different designs literally.
5:53Elon MuskSo the hard part is not can you design a staged combustion rocket engine? This has been done. Now admittedly ours is higher pressure than before and it is a full flow stage combustion, but that's a relatively minor increment relative to what the Russians have already done.
6:10Elon MuskWhat is super hard about Raptor is how do we make a Raptor where the cost per ton of Thrust is under $1,000? Yeah, I mean we definitely don't want to.
6:21Elon MuskThe fundamental thing that needs to be fixed is the cost per ton to orbit. So things that address the cost per ton to orbit are good. Like humanity will be a multi planet species if we get cost per ton to orbit to the point where we can afford to become a space ranked civilization and a multi planet spec.
6:45Elon MuskSo this is at its heart, it is fundamentally an optimization of cost per ton to orbit and then ultimately cost per ton to the surface of Mars.
6:56Tim DoddRight. Well, and if you're working on getting the cost, even when you start to think of it as dollars dollar per ton of thrust, I mean, I don't know if anyone's ever considered that as a key metric.
7:07Elon MuskYeah, you know, that's a new thing
7:10Tim Doddthat I've never thought about, you know, never considered. Well, and then even Raptor is kind of unique because now you're to also think about the instead of thrust to weight ratio when you have a fixed diameter and fixed circle area.
7:23Tim DoddYou're also worried about the nozzle exit to thrust ratio as being a pretty strong consideration too.
7:29Elon MuskYeah, you basically end up filling up all the area under the rocket. So with this version we have 29 engines. There's a lot of beeping. Not sure having this many things beep is actually helpful.
7:47Elon MuskIt's like everything around you is pr.
7:49Tim DoddIf everything's in danger, you're thinking he's
7:50Elon Muskgoing to tune it out. Yeah, exactly. So it's pretty silly. But. So this is, this is the nose of Booster four. Yeah, this is, this is Basically that's the interstage and the.
8:03Elon MuskThe fuel tank of booster four. Wow. So yeah. What are the little. So obviously those are where the grid fins go, right? Yeah. And then what's the thing in between them?
8:17Elon MuskThat's. That's basically that's actually the mount point that's there. There are two. It's debatable whether this is the right design or not. In fact, it's like all designs are wrong.
8:27Elon MuskJust a matter of how wrong. That's one of the load points for picking up the booster. So back there you see. Yeah.
8:34Tim DoddThat. Yeah.
8:35Elon MuskThis is like tiny little. It looks small.
8:38Tim DoddYeah, it looks like a.
8:40Elon MuskBut it's actually not that small. A close up. If this thing's just high in the air, like all your sense of perspective is. Is wrong. Yeah. And when this, when this lands, it has like basically the density of an.
8:51Elon MuskOf a be right anti beer can.
8:54Tim DoddRight.
8:54Elon MuskWhat is the dry mass with like some mass, you know, in the engines, obviously.
8:58Tim DoddWell, dry mass. Are you under 200 tons?
9:01Elon MuskWe should be under 200 tons.
9:09Elon MuskThe mass is a moving target. So you don't have to say like what are your propellant residuals when you land. That's a big deal. Like both how much marginal will you have and what two unusable propellant.
9:25Elon MuskLike you can't just go to zero margin, you know, because the thing's gonna crater. Yeah. So.
9:35Elon MuskIt should be under 200 tons though. So. But as a rough rule of thumb, like the engines, including mounting mass, are roughly 2 tons. So you've got 29 engines at 58 tons.
9:48Elon MuskThen the sort of the fuel tank itself and the oxygen t. Probably on the order of. Well, it's a little heavy right now, so maybe it's like 80 tons or so.
10:06Elon MuskThen you got the interstate with the. Where you've got the grid fins, batteries and a bunch of other things. So that's maybe around 20 tons. And then you got propellant residuals which might be on the order of 20 tons too.
10:27Elon MuskOkay. All that should come to, I don't know, call it 160 to 200 tons, depending on the sort of final mass numbers. But like right now everything's hit too heavy.
10:38Elon MuskLike avionics. Too heavy. The avionics even. Yeah, I thought it was just a little. I mean it should be. But the grid fins are electrically powered, so we have batteries that are energy optimized instead of power optimized.
10:55Elon MuskSo like this grid fence only needs work for like two or three minutes.
11:01Tim DoddRight?
11:01Elon MuskRight. So it's very different from like electric car, which you want to have several hours of driving. So these really. We need power optimized batteries, not energy optimized batteries.
11:13Elon MuskThis is just a short term thing.
11:14Tim DoddRight.
11:16Elon MuskSo the battery mass can probably drop by maybe a factor of 10.
11:21Tim DoddRight.
11:21Elon MuskSo that's just one example. Should we back up a little bit so it's so less banging? Yeah.
11:31Tim DoddAnd everyone Dr. To get their cranes
11:33Elon Muskin here and do work.
11:34Tim DoddYou got a lot of people on set right now.
11:37Elon MuskYeah, I mean this like that residuals number is a super big deal on the mass though, because the booster is designed to have 3,600 tons of propellant, which is an almost 80% oxygen.
11:51Elon MuskLiquid oxygen by mass.
11:52Tim DoddYeah.
11:53Elon MuskLike 78% if you burn it.
11:55Tim DoddWhat is it?
11:56Elon Musk3.5? 3.5, 3.7.
11:59Tim DoddOkay.
11:59Elon MuskYeah. So. And you want to bias it in favor of oxygen. Oxygen. Because oxygen is denser and cheaper.
12:06Tim DoddRight, right.
12:06Elon MuskSo in terms of improving your payload and you know, reducing cost per ton, oxygen is basically plants make it for free and plankton. Yeah. So it's just. It's basically like electricity cost of separation and distillation.
12:24Tim DoddRight. Now remind me though, is it like as far as the ratio goes, fuel of ratio having a lighter molecule, don't you kind of want that to be spewing out faster or something?
12:37Tim DoddBecause it's less reaction, it can accelerate it quicker.
12:41Elon MuskThere's a trade off between. Well, I mean, what you tend to get limited by is you don't want to go too close to stoichiometric because the heat basically melt your engine.
12:54Elon MuskSo that tends to limit you on the. Of trying to go to higher of. That's the actual thing limiting you. You tend to hit the stoichiometric melting point before rollover on isp.
13:09Tim DoddOkay.
13:10Elon MuskOkay. Generally.
13:11Tim DoddOkay, so that makes sense.
13:15Elon MuskYeah.
13:15Tim DoddAnd remind me of the grid fins. Are they. Do they still fold in?
13:20Elon MuskNo.
13:20Tim DoddNo. Is that going to be permanently that way?
13:24Elon MuskYeah. So the. What I'm trying to have us all just implement rigorously is the sort of five step process. First, make your requirements less dumb. Your requirements are definite, definitely dumb.
13:40Elon MuskIt does not matter who gave them to you. It's particularly dangerous if a smart person gave you the requirements because you might not question them enough.
13:48Tim DoddYeah. You might take it as like gospel, like I have to do this thing.
13:50Elon MuskEveryone's wrong. No matter who you are, everyone's wrong some of the time. So make your requirements less dumb. Then try very hard to delete the part or process. This is actually very important.
14:01Elon MuskIf you're not occasionally adding things back in, you are not deleting enough. The bias tends to be very strongly towards. Let's add this part of process step in case we need it.
14:13Elon MuskBut you can basically make in case arguments for so many things. And for a rocket that is trying to achieve. Trying to be the first fully reusable rocket. There's never been a fully reusable rocket.
14:25Elon MuskPeople don't understand like this is like the holy grail of rocketry. Okay. And so you really need. You have to run at tight margins because if you don't run tight margins you're going to get nothing to orbit.
14:40Elon MuskSo you've got to delete the portal Process step super important. And you can't like hedge your vets. So that's why the quick fins, for example, do not fold down because that's a whole extra mechanism that we don't need.
14:55Tim DoddAnd then you can often pay for it by having strong enough engine authority to steer it in the lower atmosphere.
15:01Elon MuskActually our simulation. So we don't really need any extra engine authority as long as the grid fins basically follow the flow. They're not really disturbing the flow. It's really neither here nor there.
15:15Elon MuskHave a high angle of attack, it
15:17Tim Dodddoesn't matter a few degrees or something or within a degree or two.
15:20Elon MuskSo but in any case, it's a thing we could add later.
15:22Tim DoddRight?
15:23Elon MuskSo now these grid fins are humongous. We'll go see them. But they're like, I mean like a dinosaur bear trap. Okay. It's like a beta bear trap or a dinosaur.
15:32Elon MuskThat's what these things look like. And if you have a whole mechanism for folding them, that's like clearly a part that we don't need. So this was a good design decision making that actually I didn't come up with.
15:46Elon MuskAnd it was like great. But it followed the principle of like lead the part, delete the process. I was like, great, good idea. Let's not fold them. Why were we folding them anyway?
15:56Elon MuskSomewhat random. Also, whatever requirement or constraint you have, it must come with a name, not a department. Because you can't ask the department. You have to ask a person.
16:08Elon MuskAnd that person who's putting forward the requirement or constraint must agree that they must take responsibility for that. Otherwise you can have a requirement that basically an intern two years ago randomly came up with off the cuff and they're not even at the company anymore.
16:23Elon MuskRight, but it came from the, let's say aero loads department. Actually no one in the aeroloads department actually currently agrees with that. This Is not. This has, by the way, happened several times.
16:35Tim DoddSo again, it can be literally.
16:36Elon MuskI don't want to put it on the air alert department, but there's like, it's every department.
16:41Tim DoddIt can be thought of as gospel again, but it might be something that's just totally in passing, like, yeah, yeah, or someone played too much Kerbal and had fins at the top of the rocket and then it just, you know, did this.
16:56Elon MuskThese things are often just way more silly than you think. So anyway, so step one, make your requirements less dumb. Step two, delete the part or process step. If you're not adding.
17:09Elon MuskIf you're not deleting a part or process step at least 10% of the time, basically, if not adding things back in 10% of the time, you're clearly not deleting enough.
17:17Elon MuskAnd then only. I think the third step is simplify or optimize the third step, not the first step. The reason for the third step is because it's very common.
17:29Elon MuskIt's possibly the most common error of a smart engineer is to optimize a thing that should not exist. And it's like, well, how do we get. Why would people do that?
17:40Elon MuskWell, everyone's been trained in high school and college that you've got to answer the question. Convergent logic. So you can't tell a professor your question is dumb, but you'll get a bad grade.
17:51Elon MuskYou have to answer the question. So everyone's basically, without knowing it, they got like mental straight jacket on. That is, they'll work on optimizing the thing that should simply not exist.
18:02Tim DoddRight, Right.
18:04Elon MuskI'll give you an example from way back in the day of Falcon 1. So in the original sort of like when Tom Yon and I were like, batting around like, okay, what should this rocket look like?
18:18Elon MuskI think I was literally in Tom's kitchen or something. And we had the spreadsheet and like, ok, we need to make a minimally viable rocket, like half a ton or whatever, something like that.
18:30Elon MuskAnd then initially the spreadsheet had. We had an nto. MMH Upper stage. So sort of hypergol upper stage, kind of like a variant of the TRW
18:38Tim DoddLindy, which I think Tom worked on, right?
18:42Elon MuskYeah. Well, the people who trained Tom worked on it.
18:46Tim DoddHe's not that old.
18:47Elon MuskYeah, that's tr. It was like a baby, you know, very advanced baby. But his mentors did work on Lin B. So, you know, lunar module 10 engine. So, you know, basically a penal injector.
19:08Tim DoddRight. Because that's where the pintle injector comes in. Right.
19:11Elon MuskIt can also deep throttle it and everything. So now the problem with that is how much does NTO MH cost? Oh, it's super expensive. Okay. It's like a rare chemical.
19:24Elon MuskSo even if you're like, you know, if Edison and Tesla had a baby and that baby was smarter than both of them combined and said, you, job is to optimize an NTO Mmh.
19:34Elon MuskUpper stage, you're screwed. Okay, so like, nitrogen tetroxide and monomethylhydrazine are super expensive, and they're also toxic.
19:46Tim DoddThey're super nasty.
19:47Elon MuskYeah, yeah.
19:48Tim DoddI mean, handling costs alone are probably pretty appreciative.
19:50Elon MuskI mean, I do think, like, safety is overcorrected on the ntoh. It went from, like, nobody had any protection and breathed the fumes all day to it's cyanide. Okay.
20:01Elon MuskAnd neither of those are true. It's not cyanide. You won't die. Ebol. Gustmeyer told me, like, a story of, like, when he started NASA. They actually, I think, passed around, like, a cup of, like, hydrazine so that everyone knew what hydrazine smelled like, because it sounds like a rotten egg smell or something like that.
20:19Elon MuskSo literally an open cup of hydrazine. And, like, obviously he's still alive. So that's an example of, like, don't, you know, don't optimize the thing. That shouldn't exist. We should not have intel.
20:34Elon MuskMmhopper stage right now. Dragon does have that, but that's because Dragon's got to do a lot of, like, nuanced firings of the Draco engines, you know, with very short pulse durations.
20:48Elon MuskAnd if you have a, you know, trying to have something that's not hypergolic, it's very difficult, and it can be done. Like, but if you say not. Not hypergolic and not cryogenic now, your options tend to suck.
21:02Tim DoddYeah.
21:02Elon MuskSo, you know, they start going down the peroxide, barking up the peroxide tree or something like that. And that's. Or super esoteric monoxide props. And that's like, again, back to big money.
21:16Elon MuskSo
21:20Tim Doddthat's step three.
21:22Elon MuskYeah, yeah, exactly. So getting through these are quite laborious. Sorry for the laborious explanation here. And then finally you get to step four, which is accelerate cycle time. You're moving too slowly.
21:37Elon MuskGo faster, but don't go faster until you have worked on the other three things. First, if you're digging your grave, don't dig it faster. Stop digging your grave.
21:54Elon MuskBut you can always make things go faster. And then the final step is automate. Now, I Personally made the mistake of going backwards on all five steps multiple times.
22:09Elon MuskSo I can repeat this. Yes, multiple times on Model 3 where literally I automated, accelerated, simplified and then deleted like one. One example I've talked about before is like the.
22:24Elon MuskThere were these like fiberglass mats on top of the Model 3 battery pack that were in between the full pan and the battery. And it was one point choking the battery pack production line.
22:35Elon MuskAnd I was like basically living on the battery pack production line, like trying to fix the line because it was like, it was, it was like choking the entire multi production program.
22:45Tim DoddSo
22:48Elon Muskthe first mistake was we should not have. I like try to fix the automation, like make the robot better, make it like the robot move faster, shorter path, increase the torque, Delete the reverse 720 degrees on the bolt because that's unnecessary.
23:07Elon MuskJust go forward, go forward fast. Not a 20% rate at 100% or. And instead of spackling, glue on the entire battery pack, just put little dabs of glue. Because the fiberglass mats are sandwiched between the battery pack and the floor pan anyway.
23:21Elon MuskSo all you need is something to hold it in place until you bolt the battery pack into the car. So anyway, so automating was a mistake, then accelerating was a mistake, then optimizing was a mistake.
23:34Elon MuskAnd finally I said, what the hell are these mats for? And I asked the battery safety team because they're like, are these mats for. What are these maps for?
23:44Elon MuskThey said, oh, these mats. I said, are they for fire protection or something? They said, no, they're for noise and vibration. So you don't get that. And I said, but you're the battery department.
23:52Elon MuskThen I asked an NBA noise vibration harshness team, what's it for? They said, fire safety. So literally it was like being in a Dobert cartoon. Okay? It was like, actually I feel like I'm in a Dobert cartoon quite frequently.
24:05Elon MuskSo I'm like, you know, like, is there. Are we some simulation where I like, I'm like trapped in some like Kafka esque Goldberg cartoon situation? But that's what it feels like a lot.
24:19Elon MuskSo then finally, okay, great, let's try a car with the fiberglass mats and without. And they put a microphone in both and see if you can tell the difference.
24:32Elon MuskYou cannot. You cannot tell. In fact I was like, which one is which? So we just deleted them and just bypassed this two million dollar robot cell. It was a complet pilot.
24:44Tim DoddNonsense.
24:49Elon MuskAnother mistake that tends to happen in production is too much in process testing. So when you're first Setting up a production line, you don't know where the m. Like where things are breaking.
25:00Elon MuskYou don't know where things are breaking. So you'll test like work in process at various steps because you want to isolate where's the mistake occurring. So a very common mistake issue with production lines is to have, is to not remove the end process testing after you've diagnosed where the problems are.
25:25Elon MuskSo basically if you have like a very high acceptance, if things are getting to end of line testing and are passing, then you don't need to do in process testing.
25:36Elon MuskSo but what tends to happen is there'll be like an initial like development engineering team that will be like basically debugging the production line, but then they will forget to take out the in process testing steps.
25:49Elon MuskSo then what happens is the in process tester will often choke the cycle time. It'll choke the line production time. It'll be like the limiter. It'll also have some number of false positives or false negatives.
26:03Elon MuskBut I mean they'll be like false positive. Like then you're like rejecting good parts.
26:06Tim DoddRight.
26:08Elon MuskSo really in volume production, if you have, if things are working well, you're really just taking a risk. Will this part be, will this subsystem be rejected it at.
26:22Elon MuskDuring the production process or at the end? And so you just really want to move things pretty much almost always to just test at the end of line and that's it.
26:30Elon MuskMaybe there's like one or two in process steps that are hard to test at the end of line, but that, but basically remove almost everything. There's another thing with battery pack where this is so crazy.
26:49Elon MuskLike one of the things the battery pack has to do is resist water ingress. So it has to be leak proof. So if you drive through deep water, water doesn't come into the battery pack and short out the battery pack.
26:59Elon MuskYou might have seen some of the videos of like people driving Teslas in like extremely flooded waters where it's like China, like half underwater. Yeah. I feel like there's literally a guy I believe in Kazakhstan literally drove a Model S through a submerged water tunnel.
27:14Elon MuskLike it was all the other cars were out and basically skimmed the car with the wheels and used the wheel rotation like a boat and drove out the tunnel.
27:26Elon MuskSo this is important to have the battery pack resist water ingress. But then instead of us doing a pressure test on the battery pack, we were actually pressurizing the inside of the battery pack, which was the wrong direction.
27:43Elon MuskAnd the battery pack lid was glued. We basically had resin that was not cured. And so we were just blurting out the resin, which doesn't make any damn sense because you should actually be drawing a vacuum on the pack and not trying to.
28:01Elon MuskNot pressurizing it. And especially not pressurizing it when there's uncured resin is what's holding down the battery pack. So the pack was failing quite often on the pressurization test, which should have been a vacuum test.
28:19Elon MuskAnyway.
28:20Tim DoddSpeaking of grid fin.
28:21Elon MuskYeah, great. Look at that.
28:34Tim DoddMan, that thing is huge.
28:37Elon MuskYeah, that's why it says like a dinosaur. Dinosaur bear trap.
28:43Tim DoddOh wait, that'd be a diet. Just a dinosaur trap, wouldn't it?
28:45Elon MuskYes, dinosaur trap.
28:48Tim DoddThat's insane.
28:49Elon MuskYeah. Honestly, this thing could catch a T. Rex. Oh my gosh.
28:55Tim DoddThat's crazy. And of course it's got the serrated teeth which help in the transonic regimes. Right?
29:00Elon MuskYeah.
29:01Tim DoddIs there any other reason for the teeth other than that?
29:04Elon MuskNo, it's just. Well, it actually helps in transonic and subsonic. But
29:11Tim Doddyeah, it's.
29:12Elon MuskIt's your. The effectiveness is better if you got a pointy. If it's more pointy. Basically, there is a limit to his pointiness. Sorry. Hey, Marvin. Yeah, exactly. Crushed under a bear.
29:30Elon MuskWow.
29:31Tim DoddSo how heavy are these guys?
29:34Elon MuskMan, these are. I started to think actually I don't know the number of hand, but probably at least 3 tons. I'm guessing sideballing it. This is why like when I say it's like moving target.
29:47Elon MuskThis is not the. Like, I wouldn't take this to the bank. Like it's not, you know, we'll. There's quite a lot of mess we can get out of this.
29:57Tim DoddRight, right. Yours is just good enough for now. Like that's.
30:00Elon MuskYeah, it's good enough for now. But like, you know, the. We basically just need to need like enough control authority to get this through the atmosphere and positioned well enough that when the engine's light, the engine can correct whatever error is left after the, you know, that we.
30:21Elon MuskWe couldn't take out with the grid bins.
30:22Tim DoddRight, right.
30:24Elon MuskSo.
30:27Tim DoddMan, that is crazy. Those are huge.
30:30Elon MuskYeah.
30:31Tim DoddAnd so it looks like the. The motor will mount to the. That lever arm there. Is that just a. Yeah.
30:37Elon MuskSo this is. Yeah, there's a motor that's. This will bas. React onto the dome, basically the fuel dome. So there's like kind of like a C channel around the fuel dome at the top and there's a motor that's going to rotate this with a gearbox and that's basically the load will be Reacted between the circular feature that you see there and the sort of.
31:08Elon MuskI shouldn't say C channel, sort of L channel on the dome. Just a simple sort of ring on the dome. Okay.
31:18Tim DoddAnd then. Is that. So what I'm seeing there, where there's. The rope's actually through it on the end here, is that the lever arm for the thing or is that just a.
31:26Tim DoddYeah. Wow. I see it slides over. It's like a. Yeah. Okay.
31:32Elon MuskThat's. That's basically the. That's where the motor will interact. So. Yeah.
31:40Tim DoddWow.
31:42Elon MuskBut it's just. Basically we're just using like Model 3 motors. Basically.
31:46Tim DoddYeah.
31:47Elon MuskJust so cool. Yeah. Yeah. Might as well use them.
31:51Tim DoddSo you mentioned you're, you know, really trying to simplify it. There's been talks that they're not.
31:58Elon MuskDid you state on Twitter that you
31:59Tim Doddweren't going to have cold. You're going to eliminate thrust. The cold gas thrusters or hot gas thrusters on the, on the V4 for the first orbital test.
32:06Elon MuskYeah. Well, we can, we can move to like, maybe a more quieter location.
32:10Tim DoddYeah,
32:20Elon MuskI mean, I'm pretty sure we could cut the weight of that in half. Like, that's, you know, we're not even really trying to optimize the gauge. That's just basically plate, you know, that's just like cut plate.
32:35Tim DoddRight.
32:35Elon MuskWelded together. So we first just gotta like make the damn thing work and then we'll optimize it.
32:41Tim DoddYeah, of course. Which again is something. The Soviet Union was so good. That was like minimum viable product, basically. Get it. Get it good enough to fly and test.
32:49Tim DoddAnd obviously you guys did that with starship big time. With the, with a 9, 10, 11, 15 was like, let's just get it out there, see what works, see what doesn't and iterate, you know.
32:58Elon MuskYeah. And if you look at like the, the various reasons, like where we blew up starships, like, and you looked at the risk list, none of the reasons it blew up were on the risk list.
33:08Tim DoddReally.
33:08Elon MuskYeah, it was like, no, maybe you could argue like one of them maybe was on somebody's risk list, but it wasn't brought up beforehand. It was that way.
33:17Tim DoddRight, right. So,
33:23Elon MuskI mean, there' crazy amount of new technology happening here and it's all evolving simultaneously. So we need to iron out like the unknown unknowns, so to speak.
33:39Tim DoddYeah, the unknown unknowns are the big ones. And there's. We got the new. Is that the new flapster 20 down there?
33:45Elon MuskYeah.
33:50Tim DoddSo remind me the numbering scheme because you were Talking about version 2 Raptor the other day, what we've seen so far are those version 2 yet or like the green.
34:00Tim DoddThe green nozzles or. Those aren't version 2 yet. Right. Have you started. Have you started making version two?
34:04Elon MuskWe've made parts of version two, so we're gonna make the thrust chamber. We've made the thrust chamber assembly and we have, I think, pretty much finished the design of the pumps.
34:20Elon MuskWe're gonna make pumps. So hopefully we'll have, I don't know, Ra. You know, in about a month we might be testing the first one. Okay, so. And, and will that be.
34:36Tim DoddYou said. So you're gonna be kind of producing stuff or the prototypes are kind of going to be always in Hawthorne.
34:41Elon MuskThat eventually you're going to be moving
34:42Tim Doddmass production to McGregor.
34:44Elon MuskYeah, we're doing volume production of Raptor and McGregor, but we'll keep California factory operating basically for
34:58Tim Dodddevelopment.
34:59Elon MuskDevelopment engines and the Raptor vacuum ocean.
35:02Tim DoddYeah.
35:04Elon MuskSo. Yeah. Yeah.
35:06Tim DoddSo if you're reaching 230, 230 ton on version two, what. What bar are you going to be? What's that going to be at like 300. 300?
35:13Elon MuskIs that technically. I think 298. But. But we. I think we should. Come on, we got to like, get two more bar out of that thing.
35:20Tim DoddYeah. So wait, so even now only 300 big air quotes on 300. You're getting 230 already.
35:28Elon MuskYeah, but we're opening the throat and reducing the area ratio. So the extra thrust is like. There's a slight. I think we lose like two or three seconds of isp, but we gain a lot more in thrust.
35:40Elon MuskYeah, and the increase in thrust outweighs the slight drop in isp.
35:45Tim DoddYeah. Especially on the first stage.
35:46Elon MuskYeah.
35:46Tim DoddYeah, but what's the.
35:48Elon MuskI mean, basically any thrust to weight below one is worthless.
35:50Tim DoddIt's worthless.
35:51Elon MuskYeah.
35:51Tim DoddSo if you go from 0.4 to 0.5, it's a massive leap compared to even. Yeah, yeah. Okay. That makes total sense. So the ravmac, what's that? What's currently. What's vapor thrust?
36:05Tim DoddIs it still around that same number? About 200 tons, but no,
36:10Elon Muskthe Raptor vacuum RVAC we'll call will actually be. The 230 ton thrust number is the thrust at sea level of the sea level version of the. Essentially, it's like, helpful to.
36:27Elon MuskSome people quibble about. Why are you talking about thrust in tons? That's not technically a scientific thing. It's because you can do the math in your head really easily.
36:35Elon MuskIf you have a rocket in Tons and thrust in tons.
36:38Tim DoddRight, of course.
36:39Elon MuskThat's why. And Newtons, you gotta divide by 10 all the time. This is like annoying.
36:43Tim DoddYeah.
36:44Elon MuskAnd then you only get kilograms. Now you gotta divide by 10,000 to get tons. This is ridiculous. Yeah, it is ridiculous. Okay, so you're like, this is absurd. Only a fool would use Newtons, in my opinion, for designing a rocket.
36:57Elon MuskSo. And especially big rockets, because you just like have a zillion Newtons, so. Yeah, but if you measure things in tons and you measure thrust in tons now, you know thrust to weight very easily.
37:09Tim DoddRight. So now. So is that like the only imperial thing you measure then?
37:15Elon MuskNo, these are still metric tons. Metric tons.
37:17Tim DoddOkay. Okay, that makes sense. Okay. I was getting nervous for a second.
37:20Elon MuskThe pressure is in, bar, because everybody kind of knows, like, what's one atmosphere? Yeah. So Pascal's is another trash unit. I hate Pascal's. That's. Why is it so tiny?
37:33Elon MuskIt's absurd.
37:34Tim DoddRight, Right. We just have a whole segment of units that Elon hates. And it's just.
37:41Elon MuskIt's like units that make understanding things harder instead of easier. Yeah, but everyone understands like far or atmospher, essentially. And everyone understands, like people can get their mind around a ton.
37:55Elon MuskLike, you have an intuitive sense for a ton. Okay. Like a car is like two tons. Yeah, sure, yeah.
38:01Tim DoddYou have some grass, you have some. Some context. Yeah.
38:04Elon MuskIf you got hit by a ton, you'd know what that meant. If you got hit by a pascal, it's like, I don't know, mouse part. It's like 1 Pascal.
38:12Elon MuskRight. So.
38:19Elon MuskSo the. Because there's another important principle which is
38:23Tim Doddthat
38:26Elon Muskyou really want everyone to be chief engineer. So everyone is chief engineer means that people need to understand the system at a high level to know what they. When they are making a bad optimization.
38:43Elon MuskLike when they are like, say, like we've done this many times where we've like put immense effort into reducing engine mass, but not. But hardly any effort into reducing propellant residuals or like order of magnitude less efficient reducing propellant residuals.
39:01Elon MuskAnd then you land with a literal ton of unused fuel. And actually we still kind of do that with Falcon 9. It has about its ton of unused fuel upon landing, which is pretty annoying.
39:12Elon MuskRight?
39:13Tim DoddOh, that's still not much in the grand scheme of everything. It's still not much. But that is in context, though, it still is quite a bit, though.
39:20Elon MuskYeah. But like, we spend so much effort getting a ton out of engines. Like, you know, that's sort of whatever, like 130kg per engine. Like that's. Yeah. So 120ish.
39:34Elon MuskSo. Yeah. Wow, look.
39:39Tim DoddThe sunsets out here are pretty hard to beat. That's insane.
39:45Elon MuskGod, that's amazing.
39:50Tim DoddSo congrats on the hls solidifying a little more today.
39:55Elon MuskThat was cool. Gio is a staunch defender of good contracting. Can we head over and check out the.
40:07Tim DoddThe mock up there? Because there's still a lot that we don't know about HLS publicly at least. I assume that, you know, decent amount more.
40:18Elon MuskI don't know if I do, but.
40:22Tim DoddWell, first off, I guess the most obvious one that I'm excited about is those thrusters. Oh, yes.
40:27Elon MuskOkay. So yeah, so the thrusters are a good example of running that up algorithm I just mentioned. Laboriously mentioned, which is question the requirements. Make the requirements less dumb.
40:42Elon MuskLead the part. Yep.
40:43Tim DoddSo.
40:50Elon MuskWhen looking at what does the booster actually need to do with stage separation?
41:01Elon MuskIf you put rotation into the stack before state, like before you turn off the main engines.
41:06Tim DoddYep.
41:06Elon MuskSo they're both, they're both rotating. They're going to rotate.
41:10Tim DoddSorry. Like pitching and yawning.
41:12Elon MuskYeah. So like you got the integrated stack.
41:13Tim DoddYeah.
41:14Elon MuskWe do this with Starling. With Starling.
41:17Tim DoddYeah.
41:17Elon MuskSo we rotate the stage.
41:18Tim DoddOkay. And it kind of flings it out.
41:21Elon MuskYes. But the, like, the, they, they basically have different amounts of inertia. It's initially rotational moving to linear inertia. So they basically move at different rates. So if you rotate the thing depending on where you are, you will move at a different speed.
41:39Elon MuskAnd so it automatically separates if you rotate and then separate. So there's no actual separation mechanism for the Starlink satellites. And they technically can bump into each other and occasionally, but they bump into each other at like one mile an hour.
41:52Elon MuskIt doesn't matter.
41:53Tim DoddRight, right.
41:53Elon MuskSo this balance will be fine.
41:54Tim DoddThey already made it through the pretty harsh environments of launch.
41:57Elon MuskYeah, it's fine. So, but like, I'm pretty sure this is like, this might be the only. We were like literally tossing 60 satellites off with no like, like a hay bundle of hay.
42:09Elon MuskLike, you know. Yeah. Dumping the rods that hold them down.
42:14Tim DoddYeah.
42:15Elon MuskLike a hay battery and just flinging them. And it's fine. They just separate, boot up and go to their position. So anyway, so if you go to stage step, instead of asking the attitude control thrusters, the reaction control thrusters to do the booster rotation, which is a lot of force, you have the main engines.
42:42Elon MuskInitiate. Initiate rotation. Now this is quite complex, Space Valley, because everything's got to happen in just the right way, but you basically initiate the rotation of the stack, stop the main engines, then the two will actually separate by themselves.
43:05Elon MuskAnd you need like a little bit of. We have like hall gas acs or reaction control system, depending on who you ask. It's a reaction control system or an attitude control system.
43:21Elon MuskIt's basically like small maneuvering thrusters. So you fire those on the ship. That gives you a little bit of maneuvering. And then on the booster, we actually have quite a lot of ult gas.
43:37Elon MuskLike basically the. You've got a lot of hot gaseous oxygen and hot methane, which actually have, you know, if you've got a big enough area, it's got decent thrust and vacuum.
43:52Tim DoddThe actual, the actual.
43:54Elon MuskThe vents. Yeah, just the thing you used to vent the stage.
43:57Tim DoddYeah. So not in a separate gas bottle, but literally like the ullage of the main tanks.
44:03Elon MuskYes. Okay, so just use the ullage as your, as your thrusters and just control the orientation of the venting. So it is not just venting out sideways, but it is venting in a direction that is useful, which can be sideways sometimes.
44:24Elon MuskAnyway, we've got like basically a lot of gas in this thing, which we would have to actually just vent to vacuum anyway because it's got too much gas and that's just extra mass that you don't need.
44:35Tim DoddRight.
44:36Elon MuskSo if you've got basically enough control authority because of the kicking the whole stack over before main engine cut off, plus using the ullage gas to vent, then you don't need, you don't need a separate hot gas thruster system.
44:58Elon MuskYou don't even need a cold gas thruster system. You already have hot gas for.
45:02Tim DoddFor the booster. Right.
45:04Elon MuskQuestion the requirements to leave the part.
45:05Tim DoddYes, yes. But this is only for the booster, right?
45:09Elon MuskYes. Although arguably, now you mentioned it, we might, might be wise to do this for the ship too.
45:19Tim DoddHow can you have.
45:22Elon MuskYou'd think that because at least mostly
45:24Tim Doddthe tanks are what, six or eight bars or something? The main tanks?
45:29Elon MuskYeah, they'll be like six, six ish bars.
45:32Tim DoddOkay. And so wouldn't those be pretty low pressure, you know, low ISP gas thrusters if you're only doing the gas from there. Or is there some trick you can do to.
45:43Elon MuskNo. In vacuum. Vacuum, it's different in atmosphere.
45:48Tim DoddSo
45:51Elon Musklike six bars in vacuum is actually decent. It's common to have thrusters in space. Thrusters that are, let's say eight bar. Like the Draco thrusters for that maneuver. Dragon are operating around chamber pressure of around eight or nine bars.
46:16Tim DoddWhat yeah.
46:17Elon MuskReally, you don't need like Dragon's still in psi, so it's like 120 to 130 psi. Technically it's a pressure pulse, but.
46:25Tim DoddRight.
46:26Elon MuskIt's, you know, so 120psi is like roughly eight bars, maybe eight and a half bar. So it's not that far from the chank tank pressure.
46:36Tim DoddRight. So you don't even need to store the gas in an even higher, like in a bottle. It's at like 200 bars or something. You don't even need to do that to operate rcs.
46:47Elon MuskNo. If you've got hot gas, first of all, it's like, it's, it's. We really want the ollage gas to be as hot as possible up to the point where it is impacting the, the strength of the, of the hull.
46:59Elon MuskLike, we don't want to soften the metal so much that it pops.
47:02Tim DoddBasically.
47:02Elon MuskBasically.
47:05Tim DoddSo
47:08Elon Muskthe hotter the gas is, the higher the isp. So having hot gas is good and it's already there and you already have the pressure vessel and you're going to chuck it away anyway.
47:22Elon MuskSo obviously you should use it as attitude control. So obviously. Now initially you can't do this with the ship because everything's cracked. But once the ship is mostly empty and it's delivered to orbit, it also is in the same situation with a lot of hot gas.
47:44Elon MuskSo actually we should really be. The vast majority of our maneuvering should be with the hot gas that's in the, in the ship. I think we're gonna fix that.
47:53Tim DoddJeez, that's. Yeah. Okay, so the thrusters on HLS that are gonna be around the ring, the render showed like 24 or something of like, you know, the landing.
48:04Elon MuskThose are different. Those are landing on the moon.
48:07Tim DoddOkay. Yeah. Yeah. Are those. Are those pressure fed? Like, what are those? Do you have a name for them yet or anything?
48:15Elon MuskLet's just say like, like this is, this is the tentative design right now. But with the agreement of NASA, we've. I think we may see that design evolve and it may be better, actually.
48:31Elon MuskSo.
48:39Elon MuskLike a big question here is like, can you land on the moon with the main engines or do you need a separate thruster system that's way up there? Like, basically if you land with the main engine, are you going to dig a big ditch in the.
48:54Elon MuskThe moon and then fall over because you landed in a ditch that you dug a shot? Literally dig your own grave. Yeah, that would be obviously bad, you know, so we don't want to dig our digger on Dig our own grave and then fall in it.
49:07Tim DoddRight, right.
49:09Elon MuskBut more analysis is like, I think we could probably land with the main engine and not dig a. Dig a grave and die in it. But we would have to prove that, you know, get something that's like, I don't know, the consistency of like lunar regolith and like something that's like a good analog analog of that.
49:32Elon MuskAnd then like land. Land a ship in that and see how big a hole. Big. How big is the hole that we dig?
49:38Tim DoddYeah, yeah.
49:40Elon MuskIf you've got low pressure engines that are high up, naturally you're going to have a much. You're not going to dig a hole, basically.
49:47Tim DoddRight, right, right.
49:49Elon MuskSo that's kind of like the sure thing. But I think if we can prove that the main engines do not dig a giant hole, then. Then we could land with the main engines and then not have the.
50:00Tim DoddAnd not have any of those. The ring. What about the. Are you going to have any sea level raptors on the lunar variant or. We only have vacuum optimized because I assume like on a normal starship, even at stage separation, you'll probably light all six at first just to minimize gravity loss or something.
50:20Tim DoddRight. So you'll still fire all six and probably shut down the sea levels and let the vacuum optimize. You know, like they probably do what, like half the. Half the second stage burn time or something with sea level or if you.
50:34Elon MuskWell, so the vacuum engines don't gimbal.
50:38Tim DoddYep.
50:39Elon MuskSo you'd have to have something to provide the control authority. I mean, technically you could say like. Well, if you're in a low disturbance situation, like the moon has no atmosphere, man, this is beefing city.
50:53Elon MuskYeah. So if you're not facing like a lot of atmospheric disturbances, then you need much less control authority. And you could possibly. Probably land with three just by differential throttling and three engines.
51:11Elon MuskBut if you didn't, if you lost any of the engines, you'd be toast.
51:15Tim DoddYep.
51:15Elon MuskSo probably makes sense. I don't know, probably keep the same config, you know, or like you could
51:24Tim Doddeven just have one in the middle that would offer, you know, a decent amount of gimbal authority and all that.
51:30Elon MuskIt depends on how much optimization is we're aiming for here.
51:33Tim DoddRight. Because you're only probably gonna make one of these things. Right. Are you planning on, like, is NASA wanting multiple or. Oh, my word. So by the way, I think there's a good chance that itar is.
51:43Tim DoddComms might not want all this. Wait until you see part two. It is unbelievable and I promise I'm going to get it to you as soon as I can.
51:52Tim DoddThank you Elon for spending so much time with me and allowing me to ask all of the questions I had. It was amazing. And thanks to the teams at SpaceX for allowing me to share this all with you.
52:02Tim DoddAnd thanks to Cosmic Perspective for helping shoot this and just kind of helping out all the time find them on YouTube and on Patreon as well. And I owe a huge thank you to my Patreon supporters for helping make this and everything else we do here at Everyday Astronaut possible.
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