The Stoke Space Factory Tour with CEO Andy Lapsa

0:00We do all our own software, guidance, navigation, control, power systems, other forms of avionics, communications, etc. And so this was the first incarnation of all of those things in one integrated vehicle. We flew this out at our test facility in Moses Lake. It was a modest flight, went about 30 feet high, hovered for a moment and came back down. So this is a 100 ,000 pound thrust engine. We've taken it up comfortably beyond that. We have not fully done, let's say, a thrust till you bust test yet. Well, that's coming pretty soon. Right. We had enormous conviction that full rapid reuse was the future of space travel.

0:37It is the thing that takes another zero off the cost structure of launch.

0:41Andy Lapsa: So tell me how much bigger the Block 2 fairing is going to be versus this.

0:55Hi, Mo. Andy.

0:56Andy Lapsa: Welcome to Stoke. Thanks for having us. Of course. Excited to be here. Well we're excited to have you show off what we're working on and go from there. So well tell us where we're at right now is this HQ HQ? Yeah so this is our HQ we call it HQ2 it's the second headquarters that second real headquarters we actually had a small office and then Tom's garage before that. So we're based here we do all of our engineering and manufacturing here do some as much integrated test does make sense and then we have a test facility in moses lake and launch complex in florida well we're here for a very special reason because you have two very big pieces of news so maybe we can kick that we do kick it off there um yeah so we number one we've been working on a much larger vehicle than what we've made public before so to us that's the biggest exciting thing to go public with for the first time we're calling that our block two vehicle and then the second piece is uh our series e fundraise um which is hand in hand with the block two so we have that funded and um you know green lights on on that development process how are you feeling it's great i mean it's mile a minute um what a time to be any more fun yeah um well uh i think i know what this is.

2:22So what we have in front of us is our hopper vehicle. This was our full-scale second stage prototype. It has our very unique second stage engine on the bottom with an integrated liquid cooled heat shield and then the rest of it is our first go at our also pretty unique manufacturing methods for tanks. We do all our own software guidance navigation control, power systems, other forms of avionics, communications, etc. And so this was the first incarnation of all of those things in one integrated vehicle. We flew this out at our test facility in Moses Lake. It was a modest flight, went about 30 feet high, hovered for a moment and came back down, which is super modest.

3:14We had a lot of technical objectives kind of packed into that flight plan and the reason it was so modest is uh basically you know for safety reasons um and with the faa um in case it goes rogue you have to imagine the rogue robot doing the worst possible thing and and by limiting the amount of propellant in the tanks we limit it how how far it can go and therefore draw a circle around the uh keep out zone and were you able to

3:42Andy Lapsa: to meet most of those objectives? Just about every one. Yeah, so if you watch that flight back, you'll see it take off, and then you'll see it give itself a pretty hard kick to the left. And that was our unique method for thrust vector control. Uses what's called differential thrust vector control, where you basically throttle up one side and throttle down the other to give the vehicle the kick. To my knowledge, it's the first vehicle that's been flown exclusively on differential throttle. There have been other vehicles that used a hybrid kind of form. So just showing the response rate and the overall control was important.

4:21The second thing you'll see when you watch it is it has a nice gentle roll the whole time that it's going. And one of the reasons to do that is to demonstrate what we call roll invariance of the guidance navigation control. And so even though the vehicle is spinning around, it always knows where it is in physical space. and if you imagine all of these thrusters around the side, even just to hold a position, you know, they've gotta be kind of playing.

4:47Andy Lapsa: Well, let's just maybe take a step back, talk about that for a second, because there's no gimballing function here, as you would see at a traditional kind of first stage or most second stages. Yep. So you have 24? Yeah, the flight vehicle has 24. What we're looking at actually is 30, but we reduced the number for the flight. This has one turbo pump. So maybe talk a little bit about the architecture of this. So it's a hydrogen and an oxygen vehicle. It gives it very high performance and hydrogen has uniquely good cooling capacity as well. So the vehicle is built around hydrogen and oxygen. It has one turbo pump for each propellant.

5:27And that turbo pump basically pulls low pressure propellant, pumps it up to high pressure. the propellant then gets routed around to the thrusters and then goes in and burns to produce thrust. For the hydrogen along the way we plummet through the heat shield as well and so the heat shield has very small coolant channels integral into the surface and we use that sort of as our distribution method as well for hydrogen but really what that is for is to protect the vehicle when it's coming back in from the intense heat of re-entry from space. We use the hydrogen to cool the metallic structure to protect the vehicle.

6:10And that's significant because the whole name of the game for us is full rapid reuse. Second stages really have never been reused in a meaningful way in terms of flight cadence and low touch, low inspection, low refurbishment. and the thesis here is hey if we can protect the vehicle but do it with very robust ductile metallic structures that'll you know that'll kind of pave the way to to rapid reuse and then

6:39Andy Lapsa: I mean this is the so the heat shield itself is fused or welded I should say with the valves themselves right so maybe to talk about how the heat shield and the engine kind of interplays with one another yeah so um the valves are themselves separable at this point it's pretty important early in development and at this phase to keep everything pretty modular um but the circuitry of the heat shield is integral to the engine circuit so the like i said the flow comes out of the turbo pump and then it gets routed around including through the heat shield on its way to the thrust chambers and turbo pumps um in order to power the cycle and power the engine and thrust.

7:22Now that's useful while you're flying in space. On the way back down from space, and when we're using the heat shield for re-entry cooling, the thrust chambers are actually not turned on. They're still recirculating the coolant, but they're not turned on.

7:39Andy Lapsa: I see. And is that the primary reason why you chose hydrogen for the cooling benefits? There's two reasons. One, it's an excellent coolant. It's about seven times better cooling capacity than other typical propellants you see that's number one and number two uh it gives you better um isp specific impulse or basically gas mileage for the in space part of it and so you know look for a reusable rocketry first of all it's very hard even without reusable part of rocketry to get to space right and you know you have these huge structures they're basically all propellant tanks and only the tiny tip is the thing that makes it to space so gas mileage is actually an enormous knob for us and then when you start saying hey i'm going to add more complexity i'm going to add uh landing gear i'm going to reserve propellant for the return flight you know things get even more sensitive the first stage is five-ish times less sensitive than the second stage So the second stage is really, really, really sensitive.

8:46Every pound that you reserve propellant for, for re-entry or put landing gear on or put on a heat shield, every single pound that you use is directly a pound that's not payload. So you really want to make a pretty slick design in order to make this whole worth it. And so the point is fuel efficiency matters even more in the world of reusable rocketry rocketry and it's exceptionally important for the second stage so the improvements you get

9:14Andy Lapsa: from hydrogen make a big difference you tell me if this question is premature but for nova 2 and what by the way what are you calling it nova v2 or nova 2 block 2 okay so for block 2 how is this going to change how is this architecture going to change um okay in some ways very little um the big thing that is going to be different is the thrust level will go way up on block two because it's a lot bigger vehicle. We are going to basically keep the turbo machinery pretty much the same size, but we're going to add a turbo pump for every pair of thrusters. Right now, each pair, we call them pods, each pods have its own control authority, but they're being fed by a common set of pumps.

10:01We're going to add a set of pumps for each pod, and the thrust level of each pod goes way up.

10:06Andy Lapsa: So there's going to be 12. So it's going to be 12 turbo pumps, 12 engines on this thing. Yep. And that does a handful of things. Importantly, it puts the thrust way up. Number two, it gives us a pretty slick way to what we call close the cycle and increase performance even more. And number three, it gives us engine out capability even on the upper stage. And that's something that most rockets don't have the luxury of. How many, in a situation where you're going through the re-entry process, how many of these, I guess, how many can fail before, like, do you have a tolerance around the number that can fail?

10:51How many can fail before you make mission? It's dependent on where you are on the mission. Okay. If you fail early, when you're still under gravity loss, the answer is less.

10:58Andy Lapsa: Yeah. you fail late and there is no good, you're already basically in orbit. You have actually a pretty high tolerance to failure. And in that case, the number would depend on, I guess you need two minimum. Or probably, unless you're lucky, you need at least three because you need to balance the thing. But yeah, hopefully if we have only three out of 12 working, then it's not a good day anyway. How soon into the Stoke founding did you come up with this design? Most of it was before we ever went out to raise money. That's what I would say. I would say the fundamentals of it, the idea of it, it definitely wasn't fully baked.

11:46There's a lot of more detailed design that went on, but the idea of modular thrusters, the idea of regenerative cooling, all of those things. That is what my co-founder Tom and I spent the first year of this company figuring out. And frankly, if I didn't have confidence, the reason we love this is because we feel like the physics are sound. We can put an executable development plan behind it. We're not betting on a miracle to make this work. and i wouldn't have gone out and tried to raise outside money until i felt confident that that was i could say that sentence right faith should we keep moving down does that make sense yeah

12:31Andy Lapsa: by the way when when did this all feel real to you when did it finally because you started i don't know if i've slowed down enough to like feel that feeling yet um there were a couple there were a couple moments for me one was closing the series a um it was a big enough round where i felt confident we could fly hopper off of the series a and in some ways you know it's such a weird new idea that the first i guess metric of success of this whole experiment was uh hey if i can introduce this idea to the community if i get nothing else out of this adventure then at least i've done that yeah and um after we closed the a it was like holy crap we're gonna we're gonna do that so that was really cool um to get from there all the way to orbit is a big step obviously so i would say um series c we felt pretty good that we could do it uh series d i felt like for sure we're going to be an orbital racket company we've got multiple builds um accounted for uh and that around that time we had already been thinking about block two and kind of laying the groundwork for that internally we decided to do a d2 extension and the reason for that extension was to kick start block two so that's been you know we've been doing architecture work for a while and things like that but block two allowed us to start actually moving out on hardware infrastructure, some of the material upgrades.

14:06And then this round is like, hell yeah.

14:09Andy Lapsa: I do think it's interesting you call it block two because most block one to block two upgrades are, I mean, 20, 25 % improvements in performance, but this is a substantial almost - In some ways, yes. In some ways, yes, but in some ways, no, believe it or not. So we're gonna use the same Zenith engine, which we're standing right in front of here. it was a very early let's say zenith remnant we've obviously done cutaway samples and all this stuff this guy's a built-up engine um so we did a it's going to be the same zenith engine with uh just like the next variant of it so we've already done about three block upgrades of zenith yeah that'll just be the next one um we're going to use more engines but uh the same engine basically I already described performance capability of the most recent Zenith.

15:06So this is a 100 ,000 pound thrust engine. We've taken it up comfortably beyond that. We have not fully done, let's say a thrust till you bust test yet, but that's coming pretty soon. Right. That'll give us a good idea for the limits of the current hardware. We already know some ways we're gonna upgrade the thrust level, but it'll be a modest, like I said, it's an incremental, just the next upgrade. And the big thing is we'll tighten up the packaging, increase the thrust to weight, lower the weight, things of that nature.

15:38Andy Lapsa: Well, so I mean, I have to ask, since you haven't brought up the word yet, but obviously this is one of the very few full flow stage combustion engines that are out there. So maybe just give us a little bit of like the reasoning behind the decision to go that direction and how complicated it was in the early days to get that science right. Right. Yeah. So you mentioned the full flow stage combustion. There's different architectures that you can use to build a rocket engine. Think about like in cars, you can have a diesel engine or an auto cycle versus a diesel cycle. So the same is true. There's different variants and different architectures you can build an engine on.

16:17Full flow stage combustion engine allows you to have the highest possible fuel efficiency with the lowest possible stress on the components. and for us that's the name of the game i already mentioned how important fuel efficiency is for the reusable rocket um stress on the components is very important for long life right so we want both of those it is i would say the most sophisticated version of a rocket engine that you can make for that reason it's pretty rare the russians had a program in like the 60s and there are a number of documented explosions and then that program ended um the u.s had a program uh here that um was i would say it's successful and as far as it got before the program ended and it fell short of a full engine you know integrated engine so the first time it's really been done for real is spacex's raptor engine right and then we're the second to be able to do it.

17:21So that's a pretty big feather in the cap. And then, you know, one of the most

17:25Andy Lapsa: difficult kind of risks, programmatic risks with building one of these is the start sequence. Yeah. So talk to me about how. So this was, I like to say this was the hardest decision I didn't get in the way of. I can't say I made the decision, but I did consciously make the decision not to get in the way of the decision. Okay. And the reason, I mean, it was a hard decision, right? because it's only been done once before or a small company um you know funding especially when we made that decision was not clear and um you know you kind of like going all in on this i had huge confidence in the team that we have uh we have a ton of experience just an incredibly talented small concentrated team uh and that that was the bet it's basically bet on the team um yeah so uh but now we also have to be smart about it and so as we kind of laid out what are the risks of making this decision versus something else that's more tried and true um we kind of laid them out and the one that was staring us in the face the most is start transient shut down transient right and so um we're like okay well if we can get through that then it's then then we can do it it might not be easy or smooth but we can do it um but what we didn't want is again like you know what happened with the russian program they just kept blowing up engine after engine we don't want to get stuck in that cycle and then never get to the end so what we did was say okay we got to get that into test as fast as possible as soon as possible um and even before we really had a test in so we kind of cobbled this thing together if you remember the horizontal engine firing all right yeah what we did was develop both power heads independently and then we put them together on a thrust with a thrust chamber and it was the ugliest engine we had like ground fittings on there ground valves you know not flight weight but the important flow paths were representative and so we could really learn about the start transient and um and that was really successful So that test position was only capable of about 13 seconds of test time per run.

19:46But it's enough to get the engine up to power and then back down. We did that while we were building the real test stand. And then timing worked out pretty well. Real test stand was ready. I think that was the first vertical engine. We got that thing up there. So I'm sure you've seen the image of the Raptor 1 next to the Raptor 2 versus the next Raptor. this feels like it's going to be a more uh we have a dramatic we have a similar picture for us as well um the vertical engine has gone through about three different block upgrades yeah and then obviously the horizontal what we call it the um breadboard engine yep that one um you could say is a fourth but so we're and we fired the breadboard engine in june of 24 so it's been in two years and change since then.

20:42We have our two qualification engines, our one's over 3000 seconds, the other is over 4000 seconds. We've got well over 10 ,000 seconds of test time on the Zenith. It's, you know, just kind of final polishing touch points on there, doing fleet leader testing. What do we got here?

21:04Andy Lapsa: Oh, we got ground control over here. break room, conference tables, lunch tables, play a little Space Invaders if you want. Head chefs, I assume. I forgot about that. Head chefs. Exactly.

21:23Okay. On the right is basically thrust chamber and engine assembly area. We'll show that more off-camera. On the left is our additive manufacturing center. We have a number of, let's say, more traditional or typical size print beds. And then in the back, we have a number of large format printers.

21:46Andy Lapsa: So on the additive manufacturing piece, now you guys still 3D print the nozzles of Zenith. We do. Here. And on, so I think it was eight months ago when you had Tim here, Everyday Astronaut, you said, so you 3D print the panels, and then you effectively line them up and you kind of put them together, more or less. More or less. That's my non-engineering version of that. Now, but you did say there that like with enough capital, you wanna change up that process. Let's see when we get, you know, certain processes are getting better and better. It depends what we can do internally. and it depends on speed, rate, volume, all those things.

22:28But for now, it's certainly a very powerful way to, we're going to loop in here. It's a powerful way to build quickly, let's say. We have arrived at stage one. This is stage one of the vehicle. This guy has, first of all, everything's built in-house. It comes in, starts as raw sheet metal. we do all the cutting, forming and joining in-house ourselves. We can basically at this point walk up to any part on the rocket. A lot of them have QR codes associated with them. We track all of our non-conformances this way. We track all of our acceptance testing, test results, the data that's produced during that process.

23:15That includes every part number, serial number level. um and a lot of those tests you know get part tested at a small scale they make it a larger assembly that assembly gets tested on and on and on there's a lot of you know in the old world you would have said there's a lot of paperwork associated with certifying flight for that um and it was my conviction that we're in this sass world now if if we're good and we're smart the sass should be able to abstract that paperwork all away and in the normal course of doing business, we just have those packages prepared. So that was the idea for BoltLine.

23:54And then in the long run, we wanna, yeah, we wanna get to the pad, ship this thing and fly it. But what we really wanna do is fly it day after day, hundreds of times a year. And we wanna know a couple of things. We wanna know the second it touches down that it's good to go again. We wanna know the second it touches down, one on this rocket needs scheduled maintenance. or unscheduled maintenance. And how long can it, you know, is it good to go fly again? How many more flights does it have before we have to pull it in and do that scheduled maintenance, et cetera, et cetera, right? So if you don't have the baseline, if you don't have the full configuration management and the part history being checked, then you can't do those things.

24:38Andy Lapsa: Yeah. So, you know, SpaceX doesn't have built with warp drive on the side of their booster. So is this an external marketing effort? Is there a potential scenario where you're going to sell it? We do sell it. Oh, you do sell it? Yeah, it's sold on the open market. There you go. And that business is doing well. It's doing as well as we let it. And so we're kind of, you know, its growth kind of goes along with our company's growth. And yeah, we've got some really great partners. and in general, it levels up the product, makes it a better product for us. It also helps us kind of see around corners that are really helpful.

25:21As the company grows, there might be some things that outside customers care about that we don't care about yet, but we're going to care about pretty soon. And that's been a really, really valuable thing for us already. It's helped us streamline a lot of business processes that otherwise we'd either be stuck looking for third-party suppliers that we all know we won't love, or simply just make the product better. Right, right. In front of us, we have the payload accommodations. So basically where the I-beam is connecting to the cone, that's the payload interface, and then our fairings are here.

25:56This is our second stage flight vehicle. It's kind of in final checkouts before we ship it out to Moses Lake and do a basically series of wet dress rehearsals, structural acceptance and then hot fire testing static hot fire so right now the engine and the vehicle are two separate parts but they from an avionics perspective they're all plugged in so the vehicle I don't know exactly what they're doing right now but we'll do flight simulation the vehicle thinks it's flying do all kinds of testing from that perspective have fluids and and other systems in the loop to the extent that it's safe to do in this setting and then like i said pretty soon here we'll ship it out to moses lake and start getting into the more higher energetics testing so while we're here let's just talk about hot staging for a second because you

26:49Andy Lapsa: have a very different yeah mode of hot staging and we're used to seeing with starship so maybe talk about that okay so uh the vehicle will use what's called hot staging so what happens um for the full audience is that rockets are typically two stages to orbit. The first stage sort of punches you out of the atmosphere and then falls away. But getting to orbit is actually not going up. It's more going over at a very high speed. So first stage punches you up and out and a little bit downrange. And then the second stage takes over and goes the rest of the way to the orbit. And so in that moment where the first stage drops away from the second stage, that's the staging moment and most rockets i would say uh the first stage drops away there's a momentary pause and then the second stage engine lights and takes the engine away or the vehicle away um some rockets do what's called hot staging where they actually start firing the second stage engine before you do the staging maneuver you say some rockets how many rockets actually do that I don't know that I mean it has been done it has been done right uh starship's not the first one I don't think but I'm not sure exactly all of the history so some okay but a relatively small number to your point um so you start the second stage engine before you do that separation uh and then the second stage goes away so it's gives you a little bit extra performance because you don't have a gravity loss moment uh okay Okay, so for us, we have a pretty slick way to do that.

28:28If you see the second stage engine has, remember those thrusters all around the perimeter. The diameter of the second stage engine is sits just proud of the first stage. So when we do this hot staging, we'll fire it up and the thrust, the plumes out of the second stage engine just kind of run down the side of the first stage rather than right on top of it. Which is a pretty dicey condition, I would say.

28:53Andy Lapsa: well well starship had a couple issues with hot staging in the early days yeah as you would expect right so they've done a number of iterations to make that yeah well hopefully it's more robust well so okay so there's two things that are probably coming to mind for maybe the uninitiated so your heat shield is stainless steel uh it's a metallic alloy or metallic similar to stainless steel metallic alloy similar to stainless steel um and then you have this like unique hot staging method. I'm curious, you know, versus Starship, which uses ceramic tiles, which is a big advantage for you guys not using ceramic tiles for the cooling benefits of your kind of architecture.

29:33But maybe talk a little bit about like, what are your advantages?

29:37Andy Lapsa: I don't want to say maybe versus Starship, but versus using ceramic tiles or I mean, this is maybe in general talking about that. Yeah. So this was, I mean, this was basically the founding question that we had. We had enormous conviction that full rapid reuse was the future of space travel. It is the thing that takes another zero off the cost structure of launch. It's the thing that, you know, especially lately, increases availability, allows you to scale flight frequency without scaling factories and testing and things like that. And so like full rapid reuse, whoever is able to figure that out is in pole position, right?

30:18So I mentioned full and rapid reuse is really important. So the question is, you know, like shuttle, for example, showed us that there were reusability elements that were possible, but it certainly wasn't rapid turnaround. And a big reason for that was the heat shield, which was made out of these very brittle ceramic tiles. After virtually every mission, there was damage on those tiles. So that required a very detailed and time consuming inspection and refurbishment cycle between flights. And that drove a lot of the turnaround time. You know, reentry is one of those problems that's like right at the fringe of material science physics.

31:01And so you wind up with these materials that are super, super brittle. They're not great structurally. They're hard to bond. They're hard to machine, etc. So it's like a pretty big problem. And then on top of that, these rockets get built in a room like this at room temperature, put them on a pad, you fill them up with cryogenic material and the whole thing gets minus a couple hundred degrees and shrinks. And then on their way back in, they get really hot. And so, or one side of them in particular gets really hot. And so then they start to expand and whatever heat shield or surface you have protecting the vehicle has to be able to expand and contract through that whole cycle so brittle things are not great for that um okay so that's kind of like the backdrop and we said we we can't imagine where that style of solution is going to be super robust long life rapid turnaround set it forget it you know we just it's hard for us to imagine that world where you're not going to be inspecting and refurbishing between flights so that was the like we we started the company on the thesis of full reusability we didn't really have a good answer to it uh and so that like i said before that was the first year of the the business is like seeing if we can come up with a solution and the solution we had or they came up with was this liquid cooled strategy and i would say that the aha that we had was hey the inside of rocket engines as a thermal environment it's actually about 20 times more intense than the the like the thermal environment of re-entry and we cool these things all the time with liquid cooling so can we take that idea that strategy and apply it to the vehicle for re-entry and if we can then it's not a hard problem actually from a thermal perspective we're we have like this

32:58Andy Lapsa: huge sledgehammer well so does that don't even need does that mean you can alter your re-entry course to be more aggressive in fact you're incentivized to do that okay right because um you you want to you're looking at the integrated heat load which is a function of how high hot it gets and how long it persists uh and if you can just like drop right in and take take brunt of it all at once and you wind up with a smaller total heat load. Right. So we can do that. It's not the amount of heat. It's the time period that it's going through. It's both the intensity of the heat and how long you're exposed to that intensity.

33:37Okay. Right. And so like shuttle, for example, took a very shallow kind of a swan divey re-entry in order to reduce the max heating and say, hey, I can take this longer, but I can't take it higher.

33:50Andy Lapsa: Yeah. Right. We can take it higher. no problem so we can really tailor those re-entry trajectories and importantly uh you know low earth orbit is one thing if you're coming back from the moon if you're coming from mars coming in a lot hotter right so other systems will have to kill that speed somehow in order for the material to survive and like we're g limited we're not thermal limited when are you announcing the human variant of the lander. We're going to hold our tongue on that for now. Yeah. From the very beginning, we've tried to be very capitally efficient, both in the capital infrastructure we put together and with the team that we've put together.

34:35It's still relatively small team, given the amount of scope that we're working on. And so that is kind of buried in the fiber of the company's capital efficiency and speed. So we actually have a little bit more room to grow, fill in some gaps in here. The factory will do four vehicles. We'll be on basically three months centers by the end of next year. And then we'll continue to increase the speed of production. but we'll use that extra bandwidth for the block two vehicle. In parallel, we are expanding our footprint in order to build at a higher rate on block two. Let's say if we weren't building block two in this facility, we could do seven, between seven and eight vehicles per year in this facility.

35:29So we've got the manufacturing process pretty well streamlined, but we will be expanding over time and that's a big reason you know to do the series e and you're going to focus uh testing and Moses Lake correct yeah yeah in fact we both uh just expanded the footprint of Moses Lake if you thought this was tight um Moses Lake is an incredible spot yeah we have a ton of different capabilities and test facilities in there but it's only on a 75 foot or a 75 acre footprint we just expanded that to 550.

36:07Andy Lapsa: Right. So that's a big deal. And we're gonna do more and more capabilities out there as we grow up. Amazing. Well, Andy, thanks for the factory tour. Of course. I really appreciate it. This is great. I'm glad I finally got to be here and see where all the magic happens. Awesome. Thank you. Of course.