The Billion Dollar Bet On Redesigning The Reusable Rocket
Scott Manley · 19:05 · uploaded Sep 9, 2026
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Hello, it’s Scott Manley here.
Yesterday, Stoke Space announced another billion dollars of funding. And that is pretty impressive. $2.3 billion in total. And Stoke’s secret is, well, they think that they’re going to make a 100% reusable launch vehicle.
Now, of course, SpaceX are of course making a 100% reusable launch vehicle in the form of Starship. Stoke are making a much smaller design. So their thing has the captive fairings which can deploy 2 and 1/2 tons of hardware, but they also have this fascinating design of their upper stage which is sort of conical-shaped. It has this heat shield on the base and the whole point is that the engine and the heat shield are integrated into one.
If you know rocket engines, they have their combustion chambers cooled by the propellant flowing through them. Well, Stoke, they want to flow propellant through the entire base of the heat shield and use that to protect it and then of course use the rocket engines built into the heat shield to actually steer and land the whole thing. And that is an amazing idea if it works.
So this is Stoke demonstrating their Andromeda engine back in early 2023. It has 24 nozzles around the outside fed by a pair of power heads, I believe. So there’s some level of redundancy and it can control the thrust to each of these individually so that they get thrust vector control, and then overall the interaction with the heat shield below it will give them other steering.
And they then further demonstrated this control when they flew their little hopper test vehicle which has the rough geometry of the intended upper stage. They flew it in a hop. They showed that they were able to actually control this by varying the thrust of those nozzles. They showed that those things interacted in a clean way with the surroundings and of course the heat shield so that they could lift it up and land it gently and show that recovery was in fact possible with this kind of design.
The next step was to scale up to a full launch vehicle. Now for first stage propulsion, they have their Zenith engines. These are full-flow staged combustion methalox engines. There’s going to be seven of those engines on the first Nova test flight. And these, you know, they were test firing them in 2024.
At this point, we’ve seen first and second stage hardware. We’ve seen them go through various tests at Moses Lake facility up in Washington and they’ve been testing launch infrastructure over in Florida. So we were expecting a launch maybe in the next year or so.
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And now back to the video.
And so, I’m going to say I was actually kind of surprised when I heard that they were getting another massive injection of cash. I mean, we know that rockets and spaceflight can be very expensive, but they’ve already had like $1.3 billion. So another billion dollars, I guess. Yeah, people are wanting to buy into this. They think it’s a good bet.
But what was surprising about this was that it’s really not to get the first Nova launch vehicle flying. This billion dollars is supposed to take them through to get Block Two flying. And Block Two is a radical change. And I’m going to have to explain exactly why.
So if we take a look at the Nova. So the Nova now, the original one has become the Pathfinder. This is the one that’s going to demonstrate the technology. And we saw bits of this in the video. There’s that first stage with seven engines in it. There’s that second stage with the ring of the Andromeda engines in it. And you know, they have these nice overlays here showing they have 2 and 1/2 tons of payload capacity, seven Zenith engines. And of course, there’s this Andromeda, the second stage engine here.
What’s worth noting is if you look at the heat shield on this, it doesn’t look like the asymmetric one that we saw during the hop tests. So the idea in the original design was they had a slightly skewed heat shield so that would provide asymmetric lift and that would enable steering of the vehicle.
When a spacecraft is re-entering, it needs to be able to steer as it goes through the atmosphere. It needs to correct for changes in the trajectory, variations in the atmosphere and things like that. And so typically you’ll have an offset center of mass, an angle of attack on that base, and then you will rotate, basically twist yourself and navigate to the target. Starship has to do this every time. A lot of its navigation to get on target near those landing sites is not using the engines. It’s using aerodynamics to fine-trim this.
And having a perfectly symmetric heat shield like this one appears to have, well without any offset center of mass, then it would have trouble steering. Now the taper on this is important in this design because if the spacecraft steers a little then it adjusts its angle relative to the flow of air through the atmosphere. That means that if you adjust the angle, it can come up at an angle up the sides. And if that air during re-entry hits the side too hard, it’s going to cause heating all the way up the side. So having this taper increases their control envelope without increasing the difficulty of stopping this thing from melting. You can put all your cooling in the heat shield area and still have a fair amount of control.
So this is why having the Block Two design is such a big surprise because they’ve basically got rid of that taper entirely. And they’ve been kind of coy about how they actually plan to make this thing work. But also, Block Two is massively increasing the size of this thing.
So they talk about the reuse capability. Their payload is now 15 tons and four tons to GTO, which of course implies that they’re going to be landing the upper stage after returning from GTO. Although I think that might be easy. You can just aero-brake a number of times and then perform a proper re-entry.
The first stage now has 14 engines, so it’s got twice the thrust. It’s a bit fatter, a bit taller. But yeah, the real change is the Block Two second stage with the Block Two engine. More thrust and this interesting non-tapered design on the fuselage.
So anyway, a lot of information on this change is in their blog post. This is a more technical side of the “we’ve just made a billion dollars” investment. This is Scaling Nova, and you can see these things sitting side by side and they go into a number of the technical changes and why they felt they were necessary.
They talk actually about the launch market crunch which is something that if you’re a casual observer you might think, oh, we’re just going to see more and more rockets launching. But the word on the street from people trying to buy launches is that SpaceX aren’t really interested in continuing Falcon 9 more than necessary. So there’s a lot of potential missions which are now looking for new rides and Stoke are sort of not saying this explicitly but they’re definitely implying that they’ll be there for any of those customers. They also have very similar capabilities to Falcon 9 and again you have these two things side by side and you can get an idea of the size.
First of all they talk about how Pathfinder is planning to launch and its first stage engine, the full-flow staged combustion cycle which they chose because full flow means that all of their propellant flows through both of the turbo pumps on the oxidizer and the fuel side so that you’ve got the lowest temperatures because you’ve got the highest mass flow. Therefore in theory you should get the most reusable engines. Of course, SpaceX instead has chosen to take their Raptor 3 and just put the pressure up as high as possible and make the engines which are the most extreme. They fully see those going to be reusable.
Yeah. They get a bunch of stuff in here. What I’m really looking for is the new Andromeda engine. So the new Andromeda engine is still going to have these 24 little nozzles around the outside, but the Block One version had two sets of turbo pumps and gas generators on it. The new one instead is going to have 12 independent engines running two thrust chambers each. So basically you’ve got much more redundancy and you’ve got much more ability to scale your thrust over large ranges. So they end up with more thrust on this stage obviously because they get more power heads and they believe they’re going to end up having more control. But on the other hand, I’m going to say if you’ve got 12 times the engines, you get 12 times the chance that something fails.
They’re going to use the same differential throttle thrust vector control. Yeah, DTVC. They’ve demonstrated in Hopper of course. And they’re going to have a separate pump that will circulate liquid hydrogen through the liquid-cooled surfaces when cooling is required during re-entry. They’ll still share the same propellant supply, but the system can now be designed so that they don’t need to fire the engines when they’re running the cooling system.
Okay. So the next interesting thing in this article is they talk about the distributed mini-engine architecture allows us to close the hydrogen expander cycle, raising specific impulse to more than 440 seconds, which means the engine becomes more efficient.
Now for those of you who don’t know about expander cycles because not everyone’s a rocket nerd. Expander cycle is where when the liquid hydrogen comes into the engine you use it to cool the engine, run it around the thrust chamber and then as that heats up it vaporizes and as that vaporizes it expands and you run that gas through a turbine and that powers the pumps. Now if you can then take the output of that turbine and actually inject that into the core of the engine and then burn it then you have what’s called a closed expander cycle and that’s the most efficient version.
But because of the way engines scale, as they get bigger and bigger, you end up reaching a point where you simply can’t heat up enough hydrogen. And to make the turbine work, you have to reduce the back pressure on the turbine. So you end up being forced to dump some of the hydrogen overboard or bleed it overboard. So the really big engines you see on some of these, the M3 rockets or the H3 rocket, those use expander bleed cycles. They’re still very efficient, but they’re not as efficient as the smaller engines, which use the closed cycle engine.
So that’s what they’re telling us here that the original Andromeda engine must have been an expander bleed cycle. This is a regular expander cycle and therefore they are far better.
But yes, look, the real part is the deleting of the taper. And again they want to have this shape because the shape is what customers want. They want this big fairing space on top. They can recover the fairings offshore like SpaceX and Blue Origin, but they need that thing to be big enough so the payload volume is compatible with what customers work with.
If they wanted to scale up the Pathfinder, they would still need to have that taper. And in fact, because of the way scaling works, you would either have to make a really fat rocket or you would have a really, really tiny payload space if you increase the amount of propellant carried on board.
The problem is, as I said, if you delete that taper, then you’re removing the conical feature that protects the side of your rocket. You might have noticed that many space capsules are tapered after the heat shield. So that protects the side from extra heating. So how are they going to be able to make this work?
I have a few different ideas. But speaking of ideas, I should point out that the idea of a non-tapered re-entry vehicle with a plug-nozzle type heat shield has in fact already been patented by Blue Origin. And this looks very similar to what’s there. Now, to be clear, this is a patent. This basically patents the idea. It doesn’t actually explain how it’s supposed to survive re-entry. It doesn’t go into details about any of the controllability stuff because as soon as you go into details in a patent, you limit the scope to which the patent can cover. Therefore, you want to make these things as vague as possible so the lawyers can make as much money as possible.
And so we come back to the Block Two and we look at this render and we see that it’s very, very obviously a placeholder at best. It gives you roughly the tank sizes. It gives you roughly where the payload fairing or the payload attach would be. Shows you where the engine would be, roughly how big it is, but it doesn’t include things like landing legs, which are pretty darn important for a recoverable stage. So we really shouldn’t be taking too much information from this and saying that it is set in stone.
What we do know is that this somehow has to be able to enter the atmosphere and has to be controllable. So again, they are trying to keep the air flow away from the sides of the rocket because if you have air flow hitting the side of the rocket, then that side is going to get hot and then it either melts or you need to put on heat shielding. You want to put on heat shielding rather than have your rocket melt, but that makes your thing larger and more complicated.
So perhaps this thing just comes in on a pure ballistic re-entry. And basically that means that it maintains zero angle of attack. It makes sure that the sides of the rocket don’t experience any heating or at least experience minimal amounts of heating that can be shielded with a very small amount of heat shield. The problem in that case is that you have no control, no aerodynamic control to let you adjust your landing point until you get to a regime where it’s slow enough that the side of your rocket won’t be melted. And that might be possible if you choose a very, very steep re-entry profile, if you make your adjustment very aggressively and drop down so that you’re headed much closer towards your target site. And we’ve seen steep re-entry profiles with things like the recovery capsule from the OSIRIS-REx mission. That came in from a long way away but it came down very steeply so that it could land within this like 10 mile area after traveling through interstellar distances. So that’s possible that they do this.
Another possibility is they just add a bunch of heat shielding up the side and that would increase the mass. It’s not ideal. But if you’re trying to steer this thing and you’re trying to make it fly a bit like a wing, then actually most of the heating is only going to be on one side. So you could probably get away with just adding some amount of thermal control on one side and then make that your dominant side and steer that thing in and steer it to its target.
Another option is you could actively protect the whole thing by running the engines because if you’re firing those engines, it is generating hot rocket exhaust out the bottom. But that rocket exhaust is actually slowing down the incoming air, which is going to be highly energetic. It’ll be more energetic, believe it or not, than your rocket exhaust after your rocket exhaust expands. So you can protect the sides of the rocket if you’re doing some sort of turning maneuver where it needs the sides to be exposed to the air flow, probably by firing the engines in some manner which induces the turn and simultaneously protects the side. That’s what I think we might see.
But honestly we don’t have enough information to go on. Andy’s been very—well everyone involved has been very coy about saying exactly what they’ll do. I think that what they’re really saying is they will figure it out because this is what the customer wants and this is what we’re going to see going forwards.
So yeah, I would like to see this happening in the future. This is clearly something that’s needed. It could potentially replace what Falcon 9 does these days or at least what Falcon 9 does that isn’t Starlink, because SpaceX are more than happy to move all their Starlink launches onto Starship. In fact, I believe we are going to have proper Starship Starlink launches on Starship when it launches like, I don’t know, next week. I’m saying now it’s probably next week that this thing, you know, Starship flies. This is going to be a few years down the line. But this will displace all the stuff that used to fly on Falcon 9 because SpaceX aren’t that interested in flying Falcon 9 anymore by the sound of things.
Yeah, I think that full reusability is the way forwards. We’ve seen that people are already making moves on partial reusability catching up with SpaceX and I think full reusability is what the market is ultimately going to be using.
So anyway, I thought this was like a fascinating change. It is rather a conundrum and I can’t wait to see what happens. More importantly, I can’t wait to see the Nova Pathfinder launch for the first time next year and hopefully recover and land successfully.
I’m Scott Manley. Fly safe.
Source: YouTube auto-captions on the video. Not a human-edited official transcript.
