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Tim Dodd

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382

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2023-02-02

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2023-02-02

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1. “No way, you know, and so to have this kind of access to this program is so incredible. The craziest thing is when you're driving out on highway four, it's bumpy. It's riddled with potholes now because of all the insane amount of trucks having to go out there and traffic. And you're going through this. It's just this weird, you're like, where am I? Occasionally you're seeing like you can kind of see the, I mean, you can see Mexico out your right window as you're driving down this highway, you know, and you're just sitting there, where am I? And then all of a sudden you kind of turn this corner and the trees and the brush kind of clear out and all of a sudden you get a sense of everything on the horizon. And at that point, you're pretty much five miles on the nose or eight kilometers away. And from there, you can just see through the heat haze, through the, you know, the atmospheric distortion. And you just see this weird, like, looks like a city almost on the horizon, you know? There's tons of these tall buildings. There's a weird ominous launch tower.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

2. “First off, if you have the freedom of traveling and happen to live within a reasonable, either by plane or car, it's worth going down to South Texas. So Starbase is right on the border of Mexico and the United States and various southern tip of Texas, right along the Rio Grande. And it's insane because it's right along a public highway. You can literally anyone can drive down this, assuming it's not closed for testing because they do close the highways during the week a decent amount while they're doing tests, but sands any of those days, anyone can just drive down and see these things up close and personal with their own eyes. Like we're talking, you know, from 100, 200 meters away, so two football fields away from the world's biggest, most powerful rocket. Imagine being able to do that during the, you know, Soviet Union and, you know, during the N1 and the Saturn Vine's being able to drive up right next to the launch pad.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

3. “And there's diminishing returns on that gravity loss thing in your high thrust weight ratios. So that's a pretty good compromise. Yes, it looks scary, but they could be a lot more aggressive with that yet and squeeze out even a little bit better performance, but there are diminishing returns. So that's kind of the magic number we've seen so far today, but we'll likely see that be played with.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

4. “Yeah. Yeah. The closer to the ground, the better. The more, again, the more the atmosphere is doing work. And we get into that video, really dives into gravity losses and gravity drag. The more time you're spent, every second that your rocket engine is running, Earth is stealing 9.8 meters per second of acceleration against you. There's just inherently 9.8 meters per second squared of acceleration. So every second that engine is running, the first big majority of your thrust is actually being just stolen by Earth's gravity well. So the longer you're fighting that, the more inefficient it is. So I mean, the best thing would be you flip at 100 meters off the ground. You light all your engines to maximum thrust. You pull 50 G's, you know, you land on a dime, basically. Obviously, there's no margin there. There's, you know.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

5. “I don't see the, and I think ultimately it'll win out where we don't have a one size fits all. I think that's the flaw of the space shuttle, really, is that it was trying to do everything and ended up kind of doing nothing well. But that's, I think what SpaceX has proven. I mean, SpaceX already has variants coming. There's already going to be a dedicated Lunar Lander for NASA for the Artemis program. There's already going to be a tanker variant. There's already going to be likely just a pure cargo version. There's likely going to be a human version. We'll likely see evolutions of this thing happen, you know, relatively quickly.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

6. “Over and over and over. And there's a chance that you, you know, you have just a cycler, just at the end of the day, you're just really trying to see what is most feasible, what's the most efficient, you literally have a vehicle dedicated to Mars. Mars, it's easy to do a single staged orbit. It's a lot lower gravity, a lot thinner atmosphere. You can easily do a single stage orbit. You get into orbit. You park to a dedicated transfer vehicle that goes between Earth and Mars. These things that you need, and ideally, it's nuclear powered, so it's super efficient. That gets you back to Earth. Once you're at Earth, you rendezvous again with another landing starship. And that starship might be a horizontal runway starship, you know, like.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

7. “Think we'll pretty quickly see an evolution of Starship that's like dedicated versions for certain tasks. And at the end of the day, again, if someone runs a simulation says it's actually more efficient and it's better just to land horizontally on a runway, then that's what's going to happen. It doesn't matter, but they still will develop if the ultimate goal is to land on Mars, then they'll have a dedicated Mars variant, which will likely look different than the Earth variant, you know. And they'll still probably be launched on the same booster, you know what I mean? So there's.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

8. “Maneuver, but it would still something at some point you would transition from more or less perpendicular to the airstream to, you know, a horizontal to landing vertically.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

9. “There's only 1% the atmosphere on Mars as there is on Earth, but you still want to utilize as much of that atmosphere as possible. So in the upper atmosphere, it's still going to be coming in more or less kind of perpendicular to the airstream. I guess it's probably more like 60 degrees, 70 degrees to the airstream, like where it's belly flopping. And it's going to especially do that on Mars. It's going to need to use up as let the little bit of atmosphere there is. You're coming in at insane velocities. And so even that 1% thin atmosphere is still going to do a lot of work. Now, on Mars, there's only 38% of Earth's gravity on Mars. So the belly flop maneuver is a lot. It could be a lot more conservative. You could do that at like 5,000 feet up. And it just wouldn't matter as much because there's not as much gravity loss or gravity drag. So you can kind of just more slowly, gently, you know, you don't have to do this crazy, extravagant, like belly flop, you know, flip.”

   2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

10. “They could be doing that pretty quickly because that's the thing. This ultimate thing has been to land on Mars and other planets, and Mars doesn't have a runway, doesn't have a thick enough atmosphere to utilize aerodynamic flight like that. So you have to do propulsive landing for Mars. You're going to land on an unprepared surface. So it has to be able to do this at some point. It sounds ridiculous, and it is, but the ultimate goal of it is to land on Mars.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

11. “Yeah, you have some extra mass in the wings, but so does Starship. Starship has the extra mass of those flaps and the motors and the hinges and all that stuff. I would like to see the trade on like, is it actually lighter weight? Do that versus doing what SpaceX is doing. So, yeah, I mean, that's the funny thing. I think realistically, if Elon walks in the door tomorrow and says, guys, we did some simulations and actually it's like we can get another 5,000 kilograms into space if we just land it horizontally. If we kind of give up on our ego and land horizontally, at least on Earth, then I think...”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

12. “Wow, wow, really getting very impressed, and you know, the Braun did it. Do we have other space planes like the X-37B? We have the upcoming Sierra Nevada's Dream Chaser.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

13. “To use. If things continue to play. Now, here's something I would love to see. Just saying this. If you already have these big arrow surfaces, the flaps, they also have to move. They're on heavy motors and hinges and flaps and all that stuff. I'm actually surprised that for Earth, they aren't just looking at landing at horizontally on a runway, like space shuttle. I mean Worked. The brand did it, you know, the Soviet Union is brawn. I rolled my art real hard there, sorry.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

14. “Quarter of a million pounds empty, and it's doing this flip maneuver, and it has to do all this perfectly. So the first four attempts of this were pretty spectacular failures.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

15. “And then modulate the engines to make it so the thrust is perfect so that it can control itself into a control landing. And all this is done in 500 meters, like 1500 feet. You're doing all of those things stupidly close to the ground. It looks absurd. So far, they've done five of these tests. All the first four all blew up. They're all coming in from about 10 kilometers or 33,000 feet. falling, flipping. You know, again, this thing's huge. Just the booster or just the upper stage of this is like 50 meters tall, you know, so it's 150. It's like 45 meters, about 50 meters tall, about 165 feet tall, nine meters wide, so 30 feet wide. It weighs, you know, something like, God, I don't remember if it's something like 120 metric tons, so 120,000 kilograms, you know, two.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

16. “And you have to very precisely control. So, what you have to do is now that it's done that kick, you also have to cancel out that horizontal velocity. So it's actually going to rotate beyond 90 degrees to cancel out that horizontal velocity.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

17. “They're pushed the rocket at the time the nose is at the time of lighting those engines, the nose is facing the horizon and the engines are facing the opposite horizon. So you now shot it a decent amount in the direction that you're not falling. So you have to factor that in to where you're landing because you're going to land on this precise. In this case, you're going to land on the inside the arm, the loving arms of the chopsticks, you know, the creed arms wide open and try to land inside this.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

18. “So that's a huge complication moving these fins and developing that landing algorithm and the control for a huge vehicle with flaps going in and out, in and out, in and out to stay stable. Then right as you light the engines, now all of a sudden you want the top, you want to flip the rocket 90 degrees to the rearward flaps, the bottom flaps, fold in. They tuck all the way in to minimize drag. That's going to make it want to swing down. You extend the upper flaps. That makes it so the nose wants to pitch up. You kick on the engines. They're now lighting all three engines, at least as of the last successful attempts. They light all three of the sea-level raptor engines and they're pitched all the way or 15 degrees or whatever the maximum pitch is on them. And that induces, you know, it does that kick maneuver to kick it over from horizontal to vertical. Now the problem is you lit your engines while you're horizontal. So they put some horizontal velocity into the rocket.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

19. “If we think about what it's going to take to go from horizontal to vertical, this rocket in particular that Starship has these big flaps, so it has kind of two nose flaps and two rearward flaps. The rearward flaps are a lot bigger because the majority of the mass, the engines and stuff are in the back of the vehicle. So in order to kind of be stable, and they just fold themselves inwards, like on their dihedral angle at a dihedral angle in order to increase or decrease the drag. So you can control all three axes of control while it's falling on its belly. You can control it that way using these four different fins. So you have these giant moving surfaces that take thousands of...”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

20. “So, if you're going to land with the engines, you might as well use engines that you already have, the engines that are used for the other portions of flight. So you kick those on and you use those engines to actually turn it 90 degrees from belly flopping to feet first. And that way you can use those same engines to land, and you don't have to have auxiliary landing engines. You don't have to have forces, you know, even if you were to land on its belly with a separate set of engines. Not only would those engines weigh a lot, you know, and be extra complexity, et cetera, et cetera, but you also know how to make the ship be able to handle landing, you know, like on its belly as opposed to having the forces be vertical through it.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

21. “Down, you don't have to do anything else. So SpaceX realized okay, if we flip this thing on its side and let it fall like a skydiver almost, you know, instead of like pencil diving into the pool, you're belly flopping. You're maximizing the amount of surface area that's in the windstream that's being slowed down. But obviously, in order to land, especially if you're SpaceX and, you know, Elon's obsessed with like not having different parts, you know, he wants the best part is no part”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

22. “And thank you. As it's falling, let the atmosphere do as much work as it can. And so if you have a unsymmetric, you know, it's not a ball that's falling. This is some kind of object with shape. At one face of it is going to have more surface area than the other face. So, you know, in the shape of like a cylinder, if you're falling, you know, like a soda can, if you're falling top or bottom first, it's a certain amount of surface area. If you flip that on its side, you actually have a lot more surface area. So with the same exact vehicle, you can actually have a lot more drag. You can actually slow it down a lot more using the exact same atmosphere, same vehicle, just by turning it 90 degrees, you can slow it down substantially, like three or four times slower. So that's energy that you don't have to use anywhere else. You don't have to use an engine to slow you.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

23. “Yeah, so this is definitely a first. I don't think anything's tried landing like this before, but the idea is when you're falling through the atmosphere, the atmosphere could actually do a lot of work for you. You're moving quickly. Something is falling from space. There's a lot of energy involved.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

24. “So by having two or three running, they have all three axes of control that they would need, kind of like a broomstick, you know, and bouncing a broomstick on your hand. They can just move it over. And if they need to align it to those landing nubs, you know, on the landing arms and stuff like that, then they can do that.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

25. “Well, we haven't actually, you know, we haven't to date seen the exact landing sequence, so it might be something like at first they might light up seven or something or nine or something, some number to accelerate quickly or decelerate quickly, same thing, and then shut it down to three or something for a little bit more granular control. Because unlike Falcon 9, Starship has enough engines and variability to actually, if it needed to hover, you know, to maybe more precisely align itself with the pad, it would have that capability. And especially having multiple engines, if you only have a single engine running, you can't really roll your roll access. You can do pitch and yaw because the engine is kind of like a rudder. It can move in two axes. So you can easily pitch and yaw the vehicle, but to actually induce roll along its vertical axis, you would either need like auxiliary engines to roll it, or you'd need a pair of engines so they can be opposed and do.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

26. “You can negate some of those, like there's like plume plume interactions, there's like, you know, the exhaust hitting concrete, and especially with a rocket this big, it's going to use like three Raptor engines firing, you know, if you have them firing really close to the ground, you're just gonna absolutely destroy and crater the ground. And you're gonna have to refurbish the ground and the landing pad every time or have huge landing legs that are super long and tall, you know, to make it so it's elevated enough to not do that. So yeah, you're kind of avoiding that whole mess by catching it high enough off the ground that you don't have to factor that in.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

27. “You are basically removing the mass of what would be heavy landing legs, and you're putting kind of that landing infrastructure onto a ground system. So you're not having to carry those landing legs into orbit.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

28. “By what's essentially relatively small ball joints. That holds the entire thing and so has to land very precisely on these mounts onto the launch mount. And that's what's going to just place it back onto the stand and allow it to be refueled and fly again.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

29. “And that will grab onto first, it'll grab onto the booster, pick it up off of its transporter that transports it from the production site, lifts it up, puts it down onto the launch mount, and then it will pick up the second stage or the upper stage starship and plop it down on top of the booster. And they did that for the first time last year. Actually, I think it was like Valentine's last year. It was the first time they used the chopsticks to stack it. And now they're doing it quite frequently. But ultimately, those chopsticks have to serve a second purpose. They're actually going to utilize, if you say catch, it's not so much they're going to catch the booster with these chopsticks. It's not like it's, you know, a dad trying to catch a falling child, you know. It's more that the booster and the starship will someday land on those arms. They're more or less stationary. I'm sure there's some bit of adjustment that the arms will do, but more or less the rocket's going to propulsively land and get picked up.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

30. “Oh, yeah. We all have been sitting on that stool milking With a giant hole in the middle, and that hole in the middle of that stool is where the rocket sits, and it sits on these launch clamps. And then next to it is, so that's the orbital launch mount. And then next to it, or the OLM, some people will say, next to it is the orbital launch tower, the OLT. And that is not only integral to fueling up the upper stage. The upper stage has to have propellant lines run to it so that they can fill it with propellant and all that. But it also, they ended up making it. So instead of having a big crane on site to stack the two on top of each other, they literally just used that tower as a crane. So the crane has these giant arms, lovingly called the chopsticks or the”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

31. “Yeah, so the launch pad is unique. I've never seen anything like it in the prior history of spaceflight, but it's a really simple launch stand. They basically have like this almost looks like a stool, like a milking a cow stool thing with a whole, a big giant.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

32. “Yep, so that's where for the first time they filled it completely to the brim with both liquid oxygen and liquid methane. Now they had done component level testing where they fill it with liquid nitrogen, which is, you know, it's an inert gas. So it's not like say it leaks out. It's not going to explode. You could just have a big giant pool of liquid nitrogen flooding the area, but it's not going to be an explosion. So they've done that for cryo testing to make sure all the components and stuff can handle being at cryogenic temperatures. It's kind of a good analog before you start putting your fuel in your oxidizer in there. But now as of yesterday, they fully fueled the rocket with propellant, both stages, the first stage and the second stage, while fully stacked on the pad. Like basically, I mean, it was the first sense we really got of like, this is what it's going to look like right before it takes off, you know, kind of breathing coming into life for the first time.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

33. “It was impressive. You know, everything in this is kind of iterations. And so, you know, the milestones that we're seeing, we actually have on everyday astronaut.com, we have a milestone checklist of like all the things we're hoping to see that we kind of need to see before the first orbital flight of this rocket. So a big milestone that got checked off yesterday was a wet dress rehearsal. So it's literally like fueling the rocket up, getting ready to do everything but lighting the engines basically. So we're talking about loading it with propellant all the way. This is the first time right there. Where's the most?”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

34. “The N1 had 45 mega Newtons of thrust. The Saturn V had, I think, 35 or 40 mega Newtons of thrust. And this has 75 mega Newton. So we're talking almost double. It's a lot of power.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

35. “Three Raptor engines on the booster engine or on the booster and six Raptors on the second stage. So there'll be three that are vacuum optimized and three that are sea level optimized on the upper stage that are primarily, they'll be used, I think, as stage separation anyway in space. But their main reason that they use them is they can use them for landing too, the three sea level engines to be able to propulsively land the upper stage as well.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

36. “Yeah, so Starship is currently in development, the world's largest, most powerful rocket ever built, fully reusable rocket, a two-stage rocket. So the booster is landed in all this is currently aspirational until it's working. So I'll say what it's aspirationally going to be. And obviously I have faith that that will happen, but just factually. So the booster will be reused, landed and refueled and reused. The upper stage will be landed, refueled, and reused. And ideally, rapidly in the sense not talking about months or weeks of refurbishment, but literally talking about like mild and inspections and ideally like under 24 hour reuse, you know, or you literally land it and fly it like an airplane. So it utilizes liquid methane and liquid oxygen as its propellants. It utilizes the current iterations of it are 30.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

37. “Quite it. Like I said, I don't love the look of the RX7. I don't love it, but I love it because of the engineering, I guess, that it represents. You know what I mean?”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

38. “It didn't take long for others to follow. You look at currently Hyundai's doing with their. I forget which one, like the Ionic or something like that. It's square. It's like it's boxy. It's a throwback. It's 80s. It's got these beautiful retro taillights. It's got these square headlights. It's very inspired by Cybertruck, in my opinion. I mean, it might not be. It might be coincidental that we're all kind of getting this retro future vibe, but...”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

39. “It like my taste has changed throughout the years. When I first saw a Model 3 Tesla, I thought it was the most hideous car without the Grill. I was like, this is so stupid. It took me all but two months to think that it was one of the coolest looking cars. Same with cybertruck. I mourned Cybertruck. When I first saw that. Come six months later, a year later, and I'm like, damn it, that thing's actually kind of cool”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

40. “Sounds like a really, really, really angry lawnmower. Sounds horrible. It's actually a terrible sounding car. In my opinion, it sounds just raspy and like the opposite of like a big muscle car. Like a big muscle guard is this deep guttural”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

41. “Going to take a long time for that turbo to get spooled up. So they actually did a small turbo on it and a big turbo. So the small turbo would spool up first, get some boost going through the engine, get that engine operating, get it up to speed, get some power to the wheels. And then once that kind of reaches its limit, you'd flow it into the divert the exhaust gas into the bigger turbo. It's a sequential turbo. And then that now can supplement and actually increase the, you know, overall performance of the vehicle by a lot. And I just, I think that's just so cool. It's just like the ultimate brute force out of the box thinking And it actually made it into production. You know what I mean?”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

42. “But just that the 20B is just such a cool, cool engine. And it's twin turbo sequential turbos. So they used a bigger turbo takes longer to spool up. It's using that same turbine and a compressor. And it just, if it's a large turbine, it takes more exhaust gas to get it spooled up. So if you have an engine that revs 9,000 RPM and you want to get a lot of pressure out of that turbo, you have a big turbo. It's going to take forever. Like you're going to have, you know, your floor and then like.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

43. “That's the only time. It's more that I love the engine and I like the car it's attached to it. And I'm not actually a big fan of 90s styling, you know, personally.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

44. “Lot of those things are different for me, but I'd say they are. Still, it's funny because now, maybe it's just because it's fresh on mind, but I love that mid-90s RX7, which, you know, especially in Japan, they had the 20B, a tri-rotor. That is like the coolest engine ever to me. The FD RX7. Just too darn cool, honestly.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

45. “The same physics apply for an aerospike as they would. So you just run into, you just run into a limitation. Like at some point, I'm not flowing enough propellant. It scales kind of poorly. You know what I mean? You can increase the thrust of an aerospect by making it bigger and increase the mass flow and the fuel going through the throats or the throat. But at the same time, it just at the end of the day, it's physically possible. It's a lot more complex. You have a lot of issues with cooling. And it's just you end up kind of right back where you started. So it's like, is it worth it to just keep going down this rabbit hole trying to engineer this thing to work when like you could have probably spent a 10th the amount of time just slightly increasing the performance of your normal engine in the first place, you know?”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

46. “Surface area to cool with a limited amount of fuel. Don't forget, you're using your fuel as your coolant. So if you all of a sudden now take your throw area and you have X amount of space that you need to cool, you have a limited supply. It's like this is stuff that”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

47. “In the streets that I just love. And that uses a rotary engine. On paper, the rotary engine is like more efficient, does all, you know, smaller, more efficient, all these things. But in practice, it's like the thing is actually just unreliable, hot, and blah, blah, blah, blah. Burns oil. It's kind of the same thing with the aerospike engine. Like, yes, on paper, it's more efficient, but now you have a lot more surface area of your throat area no matter what is going to have the throat of the rocket engine is always where it's the hottest you know it's the hardest thing to cool and with an aerospike if you know if it's inside out now your throat is no matter what like way bigger you know it's almost like the size of the nozzle exit normally but now it's your hardest thing to cool and you have a ton of it and you also have two edges of it no matter what so even if you have like a you know a circle inside a circle you have like a just insane amount more”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

48. “It's just not running at its maximum efficiency. As it climbs an altitude, as the ambient air gets thinner and thinner and thinner, it just inherently is pushing less and less and less against the walls of that aerospike engine. So it actually continually gets more efficient at, you know, as it climbs an altitude. As does the normal engine, but the difference is that you can use that huge expansion ratio at sea level and you can't use a huge expansion ratio at sea level with a traditional nozzle.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

49. “So, because it's inside out, the ambient pressure is pushing the exhaust gas into the wall as opposed to a conventional engine, the ambient air is actually squeezing the exhaust gas away from the walls of the engine. And that squeezing away from is what can be destructive. So since the since it's kind of inside out, the ambient air is pushing the exhaust gas into the engine walls, so you can't have flow separation. You won't have flow separation. Now what happens is, so you can have this huge, amazingly like efficient vacuum engine that has a, we'll say a 200 to 1 expansion ratio, which is really big. A lot of sea level engines are like 35, 40, 50 to 1 expansion ratios. And then in space, you know, it's common to use like 150, 180, 200 to 1 expansion ratios. So an aerospike can have something like 200 to 1. It's just that at sea level, it's kind of just getting pushed and it's kind of getting cut off early almost, but it doesn't matter. It's not like destruction.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source

50. “Actually, a limit. You can actually only expand it below, we'll say something like 70%. So you can get down to like 0.7 bar at nozzle exit before the pressure of the atmosphere is actually squeezing in on that exhaust. And tearing it away from the walls of the engine, the walls of the nozzle exit. And what happens is it's kind of unpredictable. You get these pockets, these oscillations, and they'll be so extreme that they'll end up. So, you can't lower, you can't have a bigger expansion ratio, then again, relatively speaking, something like 0.7. Like you can't go below, you can't get that pressure exit too much below ambient air pressure before flow separation can destroy the engine.”

    2023-02-02 · Lex Fridman Podcast · #356 – Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel · IDENTIFIED FROM THE TRANSCRIPT · source