Stoked on Stoke?
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- Опубліковано 28 тра 2024
- Stoke Space has come up with an interesting approach to second-stage reuse that relies on active cooling. Will their approach work and will they be able to compete with other launch companies?
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About Stoke's second stage engine, it's an open expander cycle which does have a role in Stoke's success in terms of engineering. It has a higher pressure than an RL-10 allowing higher thrust and vertical landings where the RL-10 couldn't.
Thanks for the clarification
“allowing higher thrust and vertical landings where the RL10 couldn’t”
you’re right about it being open expander, but RL10 *does* have sufficient thrust to allow vertical landings and in fact has done so on multiple occasions in the form of DC-X.
@@ryanrising2237 Yeah, though with very-low expansion nozzles which would have had incredibly poor vacuum specific impulse, possibly even as the "pseudo-spike" cluster like this.
@@ryanrising2237 Damn, got me there. I've always thought of the RL-10 as being a very weak engine, not having the TWR to theoretically fight Earth's gravity, much less actually being flown on a hopper. I can't believe that despite how much I love the program I missed that. Anyway, the open expander cycle DOES allow for more mass capability while maintaining a relatively high performance compared to the RL-10.
Tim Dodd (everyday astronaut) did an interview where they go into detail on the engine system. Stoke is an open cycle expander, with the open cycle hydrogen dumping pipe being in the middle of the base shield, which also provides positive pressure in the middle of the pseudo aerospike during engine burn. The heat exchanger in the heatshield is running during engine burn, as the pseudo aerospike does have engine plumes running over it.
During reentry, the LH2 is pumped through the heatshield by the engine turbopump, and the warm H2 gets dumped out the open cycle turbopump dumping pipe in the center of the heatshield. This creates a plume of freshly boiled H2 coming out the center of the heatshield, which makes a film cooling effect on the heatshield. I think they did mention something about some of the hydrogen going through the combustion chambers to keep them cool, but I think that was them letting the reentry plasma heat the combustion chambers and using that to provide additional thermal power for the expander turbopump to pump enough hydrogen for cooling, but don't quote me on that. You can watch the interview yourself.
I AM stoked on Stoke Space, but it is good to hear a clear, sober analysis, even if it stings a bit!
I think their upper stage plans to use an expander bleed cycle...
The turbopump is in the center and the bleed exits through the center of the heatshield; this should create an aerospike out of gas to guide the surrounding thrust.
On descent, I think the same system plans to dump gas from the center of the heatshield as part of the active cooling.
I think Andy Lapsa left Blue Origin because they were too much like old space companies - in interviews he seems pretty switched on. :)
Stoke has a patent on aerospike tech that uses a similar layout, but their second stage is going to be a vacuum stage and aerospike underperforms vacuum nozzles.
@@EagerSpace Yea, I assume the aerospike was chosen for ease of reentry, not maximum isp...
Trying to do reentry with a giant vacuum bell that protrudes a mile from the upper stage would be challenging, so I can see why they went for a more old-school 1950's plug engine config for this craft.
Personally, I like their style of engineering, it's always refreshing to see something new, even when it's also retro! :)
Very interesting, thank you for the analysis!
As a German, it would be interesting for me to see a similar analysis for European rocket companies.
Because they have a much greater effort to find a suitable launch site in Europe (and they can only fly in a limited number of orbits).
No promises, but do you have a specific one that you think is most interesting? Rocket Factory Augsburg comes up often...
@@EagerSpace Rocket Factory Augsburg would be great! (I live near them):
Their concept of cutting costs by mass producing their rockets "on an assembly line" instead of reusing them is very interesting to me! (Their fuel tanks are converted beer tanks XD)
Would be interesting to know if this can work to bring the cost down to the level of a reusable rocket!
There is always plan B: create IP that is attractive to your competitors and invite a merger or purchase outright. I think they may have that IP already, but a proven re-entry and landing of the upper stage would solidify that better, even if it means skipping landing the first stage for now
That *is* a common exit strategy. The problem I see is doing enough development to retire enough risk to make the technology attractive for acquisition. I *think* that requires some sort of second stage test, but the problem is that you need a first stage to run such a test, or you need to pay a lot of money to somebody to do the launch for you.
Maybe you could put together a non-reusable first stage to do that for you, but once again I'm concerned with the expense.
huh, interesting...............
The most obvious target would be to be bought up by Blue Origin, as both men have history with it and BO is already planning to use a hydrogen burning second stage, an enlarged version of what Stoke is making would seemingly be a drop in replacement for that existing upper stage. It also explains why their seemingly cutting cornes with steel construction and treating the first stage as an after thought. I wouldn't be surprized if they just end up having their 2nd stage launched as defacto 3rd stage on someone else rocket. The present design is really just a subscale demonstrator.
@@EagerSpace Just pay for a Falcon 9 launch using only the F9 booster. Since the booster is reusable that should be fairly cheap (and it draws the attention of SpaceX which is no bad thing: Elon has just said the most difficult thing about Starship is a reusable heat shield). Then prove that the Stoke Second Stage can work including boost from 7000 kph to orbit, re-entry and landing. It seems to me their USP is the second stage and they need to prove it works asap.
I think you need to reevaluate the overall importance having a financial CEO has on the outlook of a company to communicate with investors. A clear counterexample would be Astra. You need CEOs like Lapsa who know how the machinery works, and can accurately communicate how their mission will deliver an investor the valuation the company expects and the payloads the customer wants.
That's not what he said though, he said the founder needs to understand the tech and understand how to get investors to fund that idea. You need both.
Additionally, it's arguable that Chris Kemp had neither the financial wisdom nor the technical understanding to differentiate Astra from the other small launch companies
You make an accurate a argument- unfortunately. Afaik there is no government need for this, as cool as it is, and without a big government contract they won’t get nearly a billion dollars. SpX filled a government need and is still occupying it. BO has its own billions. RL is has DoD contracts and is barely surviving.
If Starship can deliver a pizza in a semi- truck for the same price as a car all small sat providers are in trouble .
But the Stoke idea is so cool!!!😢
I agree that the idea itself is cool, but there are so many great and cool ideas out there that have gone nowhere. Aerospike engines (which Stoke has a patent on that would make sense if their second stage was a first stage) are a great example of this - tons of cool ideas and thoughts, but there have been tons of opportunities for people to build them and nobody has done it.
I think it's the ideas that are more boring and the ideas that can actually be developed that win. SpaceX won at reuse because they could leverage their testing on top of launches they got paid for.
Starship, if it works as reliably as Falcon 9, will be a game changer.
But it’s so big. I can’t believe it’s actually going to be cheaper per launch than Falcon 9, even with full reusability. So if you can’t fill 100 tonnes of cargo, small rockets can undercut on price.
A fully reusable small to medium lift rocket (maybe even heavy lift if we go by the 90s definition which pretended the Saturn V didn’t exist) could still be competitive.
@@HALLish-jl5mo Starship will be used initially to launch Starlink 2 sats into LEO. Their ambitious plans for that alone will if successful change the industry for Internet access. And many ships 10+ will be needed to fuel starship going to the moon. Many more proposals have been floated for starship uses, but that is years away.
It first needs to meet its primary goals of rapid and frequent reuse, being able to catch starship as planned and accomplishing a lunar mission with the SLS.
I liked this video on your early thoughts. I hope we get more concrete details about their development, and are able to procure more funding this year, I imagine a lot has been spent already.
From what we've seen out of their social media, they seem to be fairly nimble, testing the first and second stage tanks, the second stage engine, and the powerhead of the first stage engine. Looks can be deceiving, but they have a lot of good stuff.
Nova is around the capability of Delta II, and roughly 12m taller than New Shepard. I think its small size will help, but at the same time, they are pursuing much more advanced technologies in this first vehicle. Which is good on the one hand, because they're taking reusability seriously, but might also be biting off more than they can chew.
The impression I got during one of the interviews (I think Tim's) was that the founders felt like Blue wasn't moving fast enough, but didn't simply want to move to SpaceX, and see if they could come up with something competitive instead, which I definitely got that sense of in their launch animation.
From what I can tell - and I really with there was more solid information out there - they are working on parts but they don't have a coherent target for getting that first vehicle into a state where you can actually fly it. Until you achieve that, I think you are just stuck doing technology. Maybe that makes you an acquisition target.
I'm pretty much down on launch as a startup area. SpaceX had a lot of advantages and wonderful timing plus they got reuse working, and that gives them a ridiculous number of advantages. Rocket Lab fought their way into orbit but isn't making (much) money on launch as SpaceX transporter eats into the low end. I don't see much opportunity for any of the new launch companies - it's hard enough to get into orbit and then you need to somehow get market share.
WRT Blue Origin, we may see New Glenn fly soon but I think they know very little about how to run a profitable commercial launch company.. Years and years of assured funding do not create organizations that know how to optimize for cost. I *suspect* that they are going to find they can launch but can't do it profitably. Much depends on what the "anybody but spacex" launch market ends like and how Rocket labs new aspirations for their own constellation end up.
Stokes looks like a virtual plug/aerospike engine without all the weird
There already exist many meaningful markets that can be addressed if reusability is achieved.
Nova will have a big market competing against partially reusable MLVs. Without reusability they could launch most existing LEO satellites (much smaller than F9 payload capacity), then with reusability they can launch constellations and with refilling in-orbit
Which specific markets are you thinking of?
@@EagerSpace Constellations are the most major market I would expect (65% of F9 launches 2018-2023, excluding Starlink this is still a third of launches). Fully reusability allows constellations to be better served by Stoke than many other partially reusable MLVs (eg. Neutron).
For constellations that aren't the size of Kuiper or Starlink, Stoke's Nova shines.
I have a suspicion that their real plan is to get far enough to convince an established space launch provider that it’s a good idea.
That company will then buy them out and actually finish it.
SpaceX and Blue Origin either have, or will soon have, working first stage reuse. SpaceX might have Starship flying reliably soon, but it’s somewhat inflexible because it’s so stupidly big. So both companies will have the experience to develop first stage reuse, but be interested in a small to medium reusable second stage. No point starting from scratch if someone’s got a basic concept hopping about.
Bingo, this exactly, at least as a plan B
I can see this as an acquisition play, but for that to work your development work has to retire a lot of the risk of the approach, and I think that means actual prototypes flying. That's the huge problem with second-stage reuse - you either need first stage reuse up and running so you can afford the prototypes or you need to be willing to spend money like water the way SpaceX has on Starship.
I'm not very optimistic about New Glenn. I think blue origin will get it flying and they have a reasonable chance of landing, but I don't think they have the corporate DNA to do it in an economically viable way. Even if you have Bezos-class money behind you, you can't afford to fly very much if - to pick a number - you are losing $100 million per flight.
I'd be happy to be wrong there; blue origin so far has been the worst waste of money trying to do space things ever and I'd love them to actually do programs that work.
@HALLish. What does "stupidly big" even mean? The whole idea of starship is get a massive amount of payload into orbit which can benefit space exploration in countless ways from space station development to moon and eventually Mars base infrastructure. Plus this afford Space X to get a larger amount of fuel to orbit for those longer trips.
@@michaeldeierhoi4096 Stupidly big means that the largest satellite ever launched was 19.6 tonnes and starship can launch 100-150 tonnes.
Per unit mass Starship may be the cheapest rocket ever, but unless you are ride sharing with lots of other satellites, that's useless. If you're satellite is 10 tonnes, do you wait until 9 other people want satellites in the same orbit?
Someone who charges twice as much per kg, but can launch when YOU want, that's still competitive
@@HALLish-jl5mo A big part of Starship's initial commercial launches will be to deploy Starlink 2 sats which the Falcon 9 cannot fit into its payload bay. And starship will also be able to launch a few hundred at a time. Thus there no need to search for other ride shares. Besides other companies will come to space X to launch their payloads when they see how much cheaper Starship is.
Plus there are other uses for starship including military uses, launching space station modules and many more uses I have not even thought of. It's really comical when some random UA-camr thinks they thought of something Space X hasn't!! 😂😅
One of the requirements you mentioned was "a founder who can make a dollar scream." Stoke has that. They have done a hop and 2nd stage design with very little money.
What is the experience of their founders running startups, managing money, dealing with investors?
@@EagerSpace Intelligent people learn as they go. Andy's killing it.
At least in terms of stokes market, my understanding is that they plan to specialize in bringing stuff back down from orbit, I’m probably wrong but I hope I can add to the conversation
This goes back to my point on markets - I'm not sure who is looking to bring payloads back down right now. Maybe if manufacturing becomes a bigger thing.
As far as active cooling...one thing I will note is that active cooling (both with air and water, though never cryogenic liquids to my knowledge) has a long history in aerospace and power generation systems, where it's used extensively in the first few stages of turbine blades and stator vanes to enable hotter combustion temperatures and greater thermal efficiency. Those systems have demonstrated field operational lives in the tens of thousands of hours, so the question for me is less "can this be made to work" and more "can they get it to work flowing cryofluids, and do they have their modeling right for the heating input and their cooling output".
Have you considered making a video about New Glenn Jarvis? The supposedly reusable upper stage?
I think it would be interesting to see your thoughts on what it would take to make the upper stage of New Glenn reusable, and what sort of payload hit there would be. I'm not completely convinced the payload would be a positive number.
Right now there seems to be three reusable upper stages being worked on, by Stoke, SpaceX and Blue Origin. You've talked about two out of the three.
I've thought about Jarvis a little. The lack of information is an issue; there's lots of information from both stroke and SpaceX plus actual hardware. A quick search on Jarvis just found speculation - blue does have a patent on an aerospike-based upper stage for new Glenn but it honestly doesn't look credible to me and the existence of a patent doesn't mean that is their real plan. I'll keep my eyes open, however.
@@EagerSpace Yeah, the lack of information is a challenge. It would have to be more towards the speculative side of what Blue *could* do, not what they *will* do.
Even if it doesn't make space, the technology might prove useful as a second stage for a rocket like New Glenn or Neutron
Maybe for New Glenn - and from what I can tell "project jarvis/clipper" is similar in approach (video in the near future).
I don't think neutron has the payload margin to put a reusable second stage on it.
Your videos are always so good!
Definitely quality over quantity.
it'll work because they have been blessed by the American spririt.
(Im exited for them)
Send this man his T-Shirt, sadly I'm too broke =D
I really want to see an operational aerospike.
I'm really wondering how much of an aerospike this engine truly is.
@@mskiptr I can't guarantee that my memory is %100 accurate, I think I heard this in the Everyday Astronaut video on stoke, it seems that the shape of an aerospike is quite variable. I imagine that some aerospike shapes are more efficient than others.
I'm going to challenge you on the "startup founder minds are rare." I don't think they are. I think "startup founders" that fit a particular frame (Stanford/MIT/U of M/CMU etc) are scarce, but if one expands the search outside the rarefied air of Sand Hill road, one will find more. Also, much of what you described that founder doing sounded more like a program manager to me, so maybe that one founder is two or three.
Finally, if they need the cost of a couple of F35 deathtraps? That's DoD rounding error.
There may be another video taking about startups as I didn't think I covered that part of the topic well.
Most founders are idea-based - what they provide and what gets them excited is the technology side of the house. That can work well in the research side of the house but often falls down in the development side. What you need in development is a clear vision, a clear path, and absolute devotion to that goal. And enough understanding of how people work to build an organization where everybody is aligned and within towards that goal. Being able to do that is the super power of the startup.
Peter Beck is a great example of this. You can tell that he is very firmly in charge of rocket Lab and devoted to success and that everybody is aligned to the vision.
If you don't have this is really hard to make things work. You often end up with a founder who just wants to do tech stuff and then somebody in charge who gets excited about the perks of being the CEO of a startup who just got a big investment from a VC.
This isn't a PM role because PMs often don't have the power that is needed and honestly they tend to be traditional management which is death to real progress.
The lack of that sort of person has been the downfall of blue origin for most of it's existence. They don't have anybody who says "x is important, y isn't, here's what our path is for the next year, toe the line of you're gone"
Apparantly SpaceX will do 3 Amazon Kuiper launches..
I've been telling anyone who will listen that SpaceX should buy Stokes and scale up their second stage. I don't think the tiles are going to work well when rapid reusability is the goal....But..... will regenerative cooling work with methyl-lox?
Can Raptor's powerpack work with Stokes design?
There are other advantages too, like no need for header tanks and insane flip maneuvers just before landings, with humans aboard.
Why don't you think tiles will work? They're they only thing that has worked in the past...
@@EagerSpace Tiles would have to be carefully inspected and some would have to be replaced. That can't be done rapidly.
And they're losing tiles on every flight.
@@scott6129 I think people focus too much on rapid reuse and too little on cheap reuse and rocket longevity. Sure having a slower reuse will require a larger fleet and thus higher interest but that is still only a few percent per year.
Replacing tiles could probably be optimized and quite cheap. It appears that so far a lot of time goes into the understanding and R&D of how to attach tile, where are the weak points, individual by hand tile replacement from non-ideal cranes/hoists, maybe not all tiles are in stock and some or produced on a case-by-case basis. Once everything is understood and all is optimized I would not be surprised that all missing and damaged tiles can be replaced by a team of people in parallel or by robots in a day or so. Furthermore careful inspection can at least be partially optimized and basic indicator-tech can be added to tiles to by more easily inspectable. Finally if tiles get cheaper it becomes interesting to also replace tiles on which there may be a small doubt.