China and Europe Hope to be 15 Years Behind SpaceX on Reusable Rockets

Ariane is working on a reusable rocket engine called Prometheus and they created animation of the Themis reusable rocket design. The Themis project will build a multiple-engine first-stage rocket that launches vertically and lands near the launch site. The Prometheus engine is a reusable liquid oxygen and methane engine that may cost as little as $1 million to build. The Prometheus engine will have a thrust of 100 tons each which is similar to the SpaceX Merlin 1D engine. The goal are rockets that are ten times cheaper. The Themis reusable European rocket could be flying around 2028-2030 but still needs full funding. China is developing the Long March 8-R as a rocket with a reusable first stage. The Long March 8-R should be flying around 2028.
Three Prometheus engines on a future Themis reusable european rocket
Long March 8-R in a presentation
SOURCES- Ariane, Youtube, China Space Agency Written By Brian Wang

65 thoughts on “China and Europe Hope to be 15 Years Behind SpaceX on Reusable Rockets”

  1. ) No. It’s a proof of concept, so they will use the easiest system first. Which, you are correct is LH2 based due the heat quick transfer it provides; however:

    1) While LH2 gets much colder, CH4 has higher density and can carry more heat overall without reaching the same pressures that cannot be handled without a robust design on the helium loop and propellant transfer from the stuff that is heated (big pressure build-up), which is too heavy. Splinting the system makes sense to avoid that.

    2) A large amount of the LH2 is never used for cooling the He loop (look at the diagram), it is sent straight into the pre-burner. So, if that amount needed for cooling is low enough, you can decrease the requirements as the primary propellant and replace the amount sent into the the pre-burner with sub-cooled CH4 by using some of the CH4 for partial cooling in a staged Brayton. The LH2 tank could be small, like very small.

    Using a third radiator system like a liquid metal based heat transfer system could allow you to transfer excess heat energy from the cooling system into the pre-burner where it would add thrust.

    The initial design is a proof of concept that the cooling system can enable sustained, atmospheric hypersonic flight. It’s necessarily the end design. LH2 is the easiest (engineering wise) for a test bed platform, but is not necessarily the only way they could do it. More money after success, could provide big changes.

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  2. The refrigeration version of the Brayton cycle is a Bell-Coleman cycle, which is a single-phase gas refrigeration cycle. It works as follows:

    1) Compress (after refrigerating the precooler).
    2) Reject heat (i.e., cool the helium).
    3) Expand.
    4) Refrigerate (i.e., accept heat from the precooler).

    But the SABRE loop does the following:

    1) Compress (which is actually just pump).
    2) Pick up heat from the precooler.
    3) Pick up still more heat from the preburner.
    4) Expand and do shaft work to run the air compressor and/or LOX pump.
    5) Reject heat.

    SABRE is using a forward sorta-kinda Brayton cycle to generate work, not a reverse Brayton to generate refrigeration. You can’t do both things in the same loop.

    The heat flow is all downhill in SABRE. Everything relies on each heat sink being colder than the working fluid, rather than doing work on the working fluid to get its temperature above the heat sink.

    Two more arguments, and then I’m going to stop trying to convince you:

    1) Don’t you think REI would have tried almost everything to avoid using LH2? Do you have any reason to believe they wouldn’t have considered what you’re proposing and used it if it worked?

    2) The only thing worse than the weight of an LH2 tank is the weight of separate LH2 and LCH4 tanks.

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  3. Use a tungsten alloy CMF heat sink to super heat the propellant in the pre-burner and a battery/high discharge capacitor system to spool up the compressors that are eventually run off the Braytons that use some of the gas expansion energy.

    Think a dual heat exchange that occurs in the pre-burner where the mostly CH4 with some LH2 passes over the heat sink that uses a liquid mercury or lead heat transfer loop between the He loop and CH4 and LH2 propellants in a Brayton cycle generator and the heat sink in the pre-burner super-heats the propellant to generate more thrust and increase cooling. It’s trying to compress He and then use it to cool air. Compression to cool a substance generates heat. If you have the right type of closed cycle for the heat transfer you can use it to increase thrust by heating propellant. It is all about transferring the heat and compressing the He to cold enough levels, which expends heat that can be used.

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  4. Ok you got me on the He not being totaly liquid. However, again it is a compression issue, just as much as a medium at high enough rates to cool the He. Stronger compression solves cooling discrepancies. The Brayton can supply a large chunk of the power needed for the increased compression needed to remove heat energy that is then used to heat the propellant during pre-combustion. You can do the compression to get the it cold,

    How do you think that this stuff works? Compression creates incredible levels of heat removal, a good chunk can be harnessed using the Brayton cycle turbines. Using a small amount of LH2 increases efficiency over the LCH4 since it can get colder. It’s a stacked system. Sure maybe you need a small amount of battery input to speed up the compressor, but that is it.

    It’s how an A/C unit works but on a grander scale. Same principles. Compression of the He solves the heat transfer problems between the use if LH2 and LCH4, It does not need to ever have a substance that gets as low in temp as LH2 gets if you compress it enough and use some of the heat to super-heat your propellant. Using a small amount of LH2 as an intermediary makes it more efficient, but would not necessarily be needed. Again, its about compression levels of the He.

    Closed cycle liquid mercury loops work great to move heat energy around.

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  5. The helium is never liquid. I’m pretty sure it’s supercritical the whole way through. It’s close enough to a Brayton that I’m OK calling it that. But it’s still limited by the efficiency of the He-LH2 heat exchanger–which is why what you’re proposing won’t work.

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  6. Yeah, OK, the helium loop is kind of a closed-loop version of a Brayton cycle:

    1-2: Compression by the He circulator.
    2-3: Heat added by the precooler and the hydrogen preburner outlet.
    3-4: Work cranking the LOX pump and the air turbo-compressor.
    4-1: Heat rejection into the He-LH2 heat exchanger. (A normal Brayton cycle would dump the working fluid while expanding it to ambient pressure, which this doesn’t. Close enough for government work.)

    The blue compressor is absolutely a Brayton compressor for the air path, with the heat added in the rocket combustion chamber and the work/heat rejection accomplished in the rocket exhaust.

    The hydrogen line is closer to a Rankine cycle than anything else, although it’s open loop and and doesn’t condense the working fluid.

    …None of which matters, because the whole system is still bounded by the necessity that the heat transferred into the He loop by the precooler and the preburner outlet, less the shaft work to the LOX pump and air compressor, has to be rejected in the He-LH2 heat exchanger. That heat rejection is only as good as its heat sink.

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  7. Do you understand how a Brayton works? The expansion of He and LH2 from liquid form to gas creates pressure, you harness that pressure with a small lightweight, but good thermal expansion property turbines that feeds a turbo compressor for the He loop. The expansion pressure feeds the turbines that power compressors.

    That compression puts the He back into liquid form where it acts as a coolant. The LH2 acts as a intermediary coolant that can be burned as propellant in superheated form in conjunction with LCH4 that is used as tertiary coolant where it is heated and used as the main propellant.

    LOX used for initial acceleration, orbital capability, and altitude changes can be used as even another coolant. Compressors powered by the Brayton generator and some batteries do the rest of the compression.

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  8. Brayton powered compressors. That is the “magic” (so much for that straw-man) that you are thinking of. Like any heat exchange system, a compressor can do it and the current design already uses them. No matter what the design calls for, they all use compressors in the Helium coolant loop, it just needs to be stronger to offset the temperature difference in the fuels. Using a LN loop in a second Brayton or a mix fuel with LH2 bleed gives you a medium that gets cold enough to do the energy transfer. Compression is the only other thing needed and with a strong enough compressor you do not need anything else to keep He in the liquid state needed for it to act as a super-coolant. Put the heat sink in the pre-burner to super-heat the fuel mix before combustion, it could give you a thermal enhanced rocket type effect if you do the entire LCH4 to LH2 to LHe heat exchange leading into the pre-burner.

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  9. Look a where the the pre-circulator and the LH2 pump meet.Also on the Tturbo pump where the yellow and blue meet. That is the Brayton. See the quarter curve, blue input arrows, that is the Brayton cycle energy input. It might not be blue, I am bad with colors. Color blindness and such. Essentially, look at the stuff going on in the top right.

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  10. If you bleed LH2 as you’re suggesting, you’re simply adding more fuel that has to be burned downstream–which is the whole problem.

    Just think of the whole helium loop as powered by magic for a second. The only thing you need to know is that the magic stops working if you don’t extract the same amount of heat from the heat exchanger as you dumped into the magical loop from the precooler.

    All of the thermodynamic jiggery-pokery done to power the helium loop and air compressor by non-magic is ultimately incidental to the fact that the only way you have to extract the heat from the loop is by dumping it into Cold Stuff going by really fast.

    LCH4 isn’t cold enough. Small amounts of LH2 don’t go by fast enough. And all the heat transfers are linear; there’s no combination that will result in a lean enough mixture to have the required Isp–except all LH2.

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  11. Hence my LH2 bleed dual/staged Brayton work-around idea. Sure you would need LH2 or LN, but it would be a small enough amount to be manageable. Hell, you could even use a LN loop as an intermediary, I get that the problem is that the LCH4 does not get cold enough for he He loop. That is why an intermediary loop or LH2 fuel bleed that acts as an intermediary could work. Having a LN loop or smallish amounts of LH2 fed into the fuel as a bleed is very manageable if the rest is LCH4. All technologies require a maturation process where these things get worked out if possible. The REL pre-cooler has achieved something very unique that has tons of potential.

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  12. Look: You need a certain mass flow of air, with a certain pressure ratio. You get that by pulling heat out of the flow through the precooler, and compressing the bejeezus out of it (which adiabatically raises its temperature, which is why it has to be so cold before compression). So far so good.

    However, you need to mix that mass of air with some amount of fuel and burn it to produce thrust. If your mixture is too fuel-rich, your specific impulse drops, because you you can’t extract all of the enthalpy of combustion from the fuel.

    So the question isn’t whether you could make an LCH4-cooled precooler work. It’s whether you can make it work and still have the fuel mass flow be low enough to have complete combustion. SABRE can’t even do that with LH2, but it’s close enough that they can at least get some useful thrust from the peripheral ramjets (which aren’t shown in the diagram, BTW). With LCH4, you can’t even get close enough to utilize the ramjet trick, because the volume of excess fuel is so large that the ram drag of the amount of air needed for combustion exceeds the thrust that’s produced by the combustion.

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  13. BTW, I don’t think that the helium loop actually is a Brayton cycle. It’s certainly not dumping heat through an isentropic expansion; it’s dumping through a presumably isobaric heat exchanger.

    Same thing for the hydrogen loop upstream of the preburner; that’s just two different sections of shaft work.

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  14. True, it was not an engine test. It was just to show it could cool air fast enough to make usable for generating thrust and to show it could sustain itself by using the heat exchange to power its compressors.

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  15. That’s not my problem with what you’re saying. My problem is that the heat exchanger can’t exchange enough heat if the heat sink is as warm as LCH4.

    If you had to run a preburner to power the helium loop, that might be OK, but there’s no magic to that primary heat exchange between the hot helium and the cold fuel. If the fuel isn’t cold enough, it can’t exchange enough heat.

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  16. In that diagram the most important part is the Turbo Compressor and heat exchange with the He and H. That is where the Brayton fits in, it is both, Using the energy of the heat exchange to power the compressor.

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  17. In the actual test of the precooler they used a liquid nitrogen boil in lieu of LH2 to power the Brayton powered pumps that keep the He coolant loop compressed.

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  18. That is exactly what I was describing in words. Maybe you should learn to read. I was offering up a possible work-around the LH2 problem by using LCH4 with a lower flow LH2 bleed for optimizing the Brayton cycle generator for the Helium loop. Using then a secondary Brayton (since it is just a heat exchange engine) between the Helium to LH2 bleed to LCH4 fuel with a dual stage Brayton cycle. That way LCH4 could be the primary propellant with only a small amount of LH2 to work the exchange. The Brayton cycle engine on the heat exchange between the LH2 and Helium coolant is used as the heat exchange to power those pumps. You forgot the diagram for that, the most important aspect of your rebuttal.

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  19. I understand that the precooler isn’t cooling the fuel. In fact, it’s just the opposite: the fuel is providing the heat sink for the precooler.

    You need to look at the block diagram again:
    https://upload.wikimedia.org/wikipedia/en/d/dc/Sabre_cycle_m.jpg

    The precooler is just a heat exchanger, and it works because there’s high-mass-flow supercritical helium flowing through it at an extremely low temperature. The helium transfers the heat picked up in the precooler to the fuel, allowing the helium to be recycled back to the precooler to pick up more heat from the air. The cold (very cold) fuel acts as a heat sink, and the heat is dumped overboard as part of the combustion process.

    Because LCH4 can’t go below 90 K, it would require a huge mass flow to get the precooler to cool the air enough. That fuel flow would be so large that there’d be no way to burn that amount of gaseous methane with the cold air flow produced by the precooler. They’d have to dump fuel overboard without burning it, and specific impulse would plummet.

    It’s even a near thing with liquid hydrogen at 20 K. They wind up burning some H2 in a set of ramjets around the outside of the engine. But the bypass air for the ram induces lots of drag, and there’s a limit on how much you can have without losing thrust. Because so much LCH4 would be needed for cooling, the ramjet trick won’t work.

    The precooler is useless without the thrust cycle to back it up. And it will only work with LH2.

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  20. Love the idea, air-breathing nuclear rockets are the best of both worlds. best of all you wouldn’t need oxygen in the air to work. Best case scenario oxygenated air with some super heated fuel injected in the air-stream would really move the rocket.

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  21. I think China would launch with nuclear thermal rockets before Europe and the States probably so to truly leapfrog fully reusable chemical rockets you need nuclear or some denser energy source. maybe the States or Russia has something up their sleeve after they let private companies control the reusable heavy lifting chemical rocket market.

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  22. My main point being that the cooler alone is a crucial piece of tech that could allow for viable air-breathing hyper-sonic aviation to exist, Of course it will need some modification to allow it to be commercially viable. However, the ability to cool air that quickly with a lightweight design, is very important for all air-breathing hyper-sonic aerospace. If you can make the LH2 needed for the cooler Brayton to be a small enough amount, you can use LCH4 or even sub-cooled Kerosene as a main propellant and create a dual Brayton to power the system. Yes, you might need some LH2, but it does not have to be that much and a few lithium batteries and light weight electric motors can make up the difference.

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  23. You are off by a long shot. The cooler is for incoming atmospheric oxygen, it has nothing to do with the LCH4 cooling. That would be loaded cooled as the propellant. The super-cooler takes the incoming atmosphere and cools it sufficiently at hyper-sonic speeds to allow for it to be used in lieu of stored LOX that is needed for ignition with propellant which is ignited in the 2nd stage of the engine, after the cooler (currently LH2 but could easily be LCH4). The whole issue with hyper-sonic speeds at atmosphere is the friction heat the air creates as it enters the engine makes said air unusable and creates engine damage if you do not use crazy heavy/dense heat resistant metals. I mentioned the LCH4 because the current design calls for it to be used as a deicer in the cooler. Maybe you just go dual fuel mix LCH4 with a small amount of LH2 also fed into the system as a coolant bleed to keep the helium cooler Brayton cycle active. Braytons are pretty lightweight in concept, maybe go with a double Brayton: Hellium to LH2 to LCH4. The whole Brayton concept is about heat exchange energy transfer, so you want a gradation in substance transition point temps.

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  24. The problem is that LCH4 can be subcooled to 91 K, while LH2 can be subcooled to 15 K. Helium only has a specific heat of 5.2 kJ/kg-K, so goosing its inlet temperature by 76 kelvins hurts a lot.

    In terms of the actual heat capacity of the LH2 vs LCH4, LCH4 wins handily. But its melting point doesn’t really drop with pressure, so there’s no possibility of getting it cold enough to be a working fluid for the SABRE’s helium heat exchanger.

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  25. Their chief piece of tech is the super-cooler they created. That piece of tech may be adaptable for a methane based engine. That would be a game changer. It is already supposed to use meth for active deicing of the cooler during operation.

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  26. SABRE would be a lot more interesting if you could use some fuel other than LH2, but it’s already having to run ramjets on the outside of the engine because they need more hydrogen as a heat sink than they do as a fuel into the combustion chamber.

    The military hates liquid hydrogen. It’s hard to handle, nasty to store, bulky, and the refueling infrastructure is an… unfortunate thing to have in your logistical tail if somebody’s shooting at you.

    Similarly, civil aviation is awfully fond of kerosene because it’s cheap, safe, and easy to store. LH2 fails on all three of those.

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  27. SpaceX has pretty much everyone beat in everything at the moment. However, REL with the SABRE has some engine tech that has P&W/GE type level of potential in terms of widespread use. Their engine is not just an orbital STO engine concept, but it is a hypersonic weapons platform for atmospheric flight and possible revolution in civil aviation.

    I think due to the military applications and general rules of economies of scale it has a higher potential as an all around replacement for the turbine jet than people realize. In terms of early applications, think the civil applications of a mach 5 business jet. The highest profit seats on any airline are the business and 1st class ones.

    Also, think about a good chunk of a trillion dollar 6th gen fighter program. In terms of air-breathing, sustained engine tech for atmospheric hypersonic flight, the SABRE concepts are probably the best thing going. About 30-50% of the cost of any aircraft is the engines. Now take a 1 trillion USA 6th gen fighter program and give an engine contract to REL. Instantly = a butt ton of capital investment. Then, economies of scale takes over for civil use.

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  28. It’s not about actual time but how fast the competition can work. I’d say SpaceX is 10 years ahead of the Chinese and 20-25 years ahead of the Europeans.

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  29. Agree, made more interesting in that Musk primary objective is not profit its Mars.
    Starship is overbuild for commercial use, its basically an fully reusable saturn 5 who can be refueled in orbit.

    It that you want going to Mars, not that you want launching satellites, it will work for that too and very well as its fully reusable.

    In short plan for second stage recovery or you are not playing.

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  30. Its way easier to copycat, but we are getting into the setting there you either can do 100 ton to LEO fully reusable or be an space program just because national security like Israel or Brazil.
    Note that you want an scaled down launcher for most uses.

    Yes you can get better performance going air breathing or nuclear.
    But that is the hard part.

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  31. As raw launch costs come down, total cost/mass to a particular orbit becomes more important. But there are a lot of different sized payloads, and that leads to a lot of different total costs. Some things that go into total cost:

    1) Raw launch cost. (SpaceX will likely win handily.)
    2) Insurance costs. (Lower if insurers don’t have to fate-share a bunch of payloads, which militates toward more modestly sized launchers. Also obviously lower based on launcher reliability, which ULA has used to good advantage.)
    3) Integration cost. (ULA does pretty well on vertical integration capability today.)
    4) Time between order and launch. (SpaceX is currently terrible at this.)
    5) Total mission time. (Hint: refueling on-orbit isn’t going to help.)
    6) Fairing volume. (Starship should be fine here, but it remains to be seen where the sweet spots are.)
    7) Multi-payload capability. (New Glenn seems to be spending a lot of time making dual launch to GTO as easy to integrate as possible, but this is something where Ariane has a lot of experience.)

    There are going to be lots of ways to get a piece of the launcher market. At some point, SpaceX will have to decide how many of them it’s willing to compete for.

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  32. “SpaceX will have to make better business decisions to stay ahead. ”

    That’s why I said they’ll stay ahead as long as Musk is in control. He’s determined to run as fast as possible even when the competition is left far behind.

    Once SpaceX has conventional management, kiss that goodbye: They’ll get fat and happy, switch to profit taking instead of intensive R&D, and their lead will evaporate.

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  33. BS. Did Douglas or Lockheed leapfrog Boeing? Did Airbus leapfrog Boeing? Nope… they all built roughly the same kind of airplanes. Airbus entered the field quite late but is now on par with Boeing. Its marketing and sales decisions that kept them in business or caused them to fail, not who got there first. SpaceX will have to make better business decisions to stay ahead. Look for the leaders in the field of commercial aviation when it was getting started. Curtis, Wright, Martin, Burgess, Vultee. You don’t see their names on commercial airplanes unless they are buried under the logo of another company that acquired them when they hit hard times many, many years ago.

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  34. The systems became ‘Good enough’ for the job they were intended to do: Nuclear delivery, national space assets, prestige. Governments were steering the demand. First a stable commercial customer-base needed to arise, which took form in the telsat community. It gave rise to international commercial competition from the Uk (ended), Arianespace (continued), India (increasing) and China (increasing). Then we had Zubrin inspiring NASA and a worldwide community of engineers that Mars was within our grasp within a very reasonable budget. The X-33 failure was a catalyst for others to try (Bezos and Muskhead). After that the cubesat revolution and Peter Diamandis with his X-prize modeled after the Orteig prize competition for aviation needed to come, both expanding the customer and developer base. And suddenly…voila. We have a large set of international competitors (50+ space launch businesses have sprung up in the last decade) to try to do better all developing different solutions for the same problem of getting into space.

    The difference is that the private investor community is showing more interest than ever. 13B has been invested not by governments but by private investors since 2009 in an exponential fashion.

    The future for new technology to spring up soon is bright, most people just don’t know it yet.

    Governments are very important as launch customers in budding niche markets (e.g. propellant from Lunar rock, first lander able to deliver 10mton cargo to Mars, etc.)

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  35. With SHSS and all the tech advances they are putting together (risky as it is) SpaceX is creating a nearly optimal super heavy launch system that will be near the theoretical limits of a purely chemical propulsive system. While this is 15 years ahead of the rest, F9 tech is maybe 5 years … since the F9 has shown that this is reliable and affordable … and many of the parameters teh design are public record. The special sauce is in the control systems and software and hopefully they can keep this well locked down. Nuke rockets are the last step beyond chemical … and only China and Russia will launch them. But if we want a big push of humans into LEO and the Moon in the next 20 years we might be hoping for a strong Chinese effort … they have will and the money (at the moment) for the big payloads needed to get the SHSS space ecosystem going. No one else is discussing big Space but SpaceX and China.

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  36. Elon as a driven, smart, continuous innovator, will always be a moving target to catch up to. Looking at all his companies you can see it’s not only about rocket reusability. The are continuous improvements in all things he does. However he is not fundamentally profit driven. Only to the extent that it facilitates his vision. Hence if a vision becomes fore filled he may be happy to give the game away.

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  37. The reason there has been so little progress in launch systems since the 1970s is fear of risky new technologies. I don’t think anything new could be adopted by these state players, any more than NASA could.

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  38. Sure, they don’t have to match SpaceX to build and launch rockets, so long as they’ve got a captive market. But they’ll still be behind SpaceX, and nobody is going to be launching on Chinese boosters unless they have to, or somebody’s been bribed.

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  39. The trick to flying paper rockets is to have a person come in and say they’re just going to execute. The shuttle was a bad design conceptually, on paper (and in reality). safety requirements were the first pesky details to flow out of the window…. but they still were able to make it kinda work, albeit with a prayer.

    There still is no good answer to the question whether the X-15 (or the Sanger ideas) would have been the right path to pursue instead of rockets. A SABRE-like engine could have been invented sixty years ago.

    The issue today is shaving off cost. In that line of thinking, (and if it were actually cheaper) a paper rocket would no longer be an impossibility. Paper is structurally strong (plenty of variations in the fiber mix), can be light-weighted and actually could make for an excellent ablative heat shield (and so does edible dough). Someone, e.g. a Chinaman who keeps pondering why indeed the first rockets were built out of paper and bamboo, could pursue the idea 😉

    I understand that the SR-71 flew with leaking fuel tanks. Only when the bird got up to temperature and the titanium expanded, did the seams close. No sensible engineer would have designed a plane with leaking fuel tanks, but it was a necessary piece to make the puzzle work.

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  40. To really make the most of the advantages of nuclear you need to make major breakthroughs on ion engines or something similar that can accelerate atoms to several tens of thousands miles an hour or even a significant fraction of the speed of light. And not just a few atoms at a time. If your nozzle velocity is pretty much the same as conventional rockets, then you achieve nothing. It would not mater that your reactor still has plenty of fuel, you would have no mass to throw the other direction for acceleration. The trick is to conserve the mass of the propellant by projecting it at very high speed so you don’t run out quickly.
    Though, there is a middle ground. An air breathing nuclear rocket could just propel air until there was no useful atmosphere retaining full propellant tanks…then switch modes. Could even accelerate so fast in the atmosphere that it is well beyond escape velocity before it leaves…assuming you want it to go beyond orbit.

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  41. An air breathing first stage should look more like the SR-71 than a jumbo jet. The SR-71’s first flight was back in 1964, Allen’s “Stratolaunch” is something of a joke. It’s not even supersonic!

    Perhaps something useful will actually come of the current hypersonic arms race?

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  42. Existing NTR designs have low thrust-to-weight ratios, so are not useful for launch from Earth. Air-breathing engines, on the other hand, have much better Isp’s (about 2000 seconds vs 900 for NTR), and already have widespread use. They can function as a booster stage until you run out of air, after which a rocket 2nd stage finishes the job.

    Partial space elevators can reasonably replace 30% of the job of reaching orbit. These hand down from orbit, but not all the way to the ground. Being shorter, they can be built with existing materials. Using both airbreathing and elevators would replace about half the delta-V to orbit, and raise payload fraction of the rocket stage from ~3.5 to 27%. That would be a leapfrog improvement.

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  43. Knowing that it is achievable is half the battle. The 15 yrs gap can be leaped in just a few years. You don’t have to convince management to front the money.

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  44. I’m thinking someone will go back to the aerospike design for reusability…especially for a second stage that can have multiple burns at different atmospheres/vacuum for orbit, moon, mars.

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  45. Sure, in principle there’s no huge breakthrough in what SpaceX is doing. But there is going to be a growing library of practical solutions to the problems you can’t quite anticipate, kept proprietary because they’re not obvious from looking at the rocket. Coatings, welding techniques, little hacks.

    Back during the SR-71 program, they had some early failures because the workers were using cadmium pencils to jot notes on the titanium skin segments, and during heat treat that would locally mess with the alloying. Sure, if somebody brought the issue up, a metallurgist could have told them not to do that, but in the real world they had to have the failures to know it was an issue and get past it.

    That’s the stuff real world testing provides you, that turns a paper rocket into one that flies reliably. Finding one failure mode after another and eliminating it.

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  46. Rather than copy SpaceX’s technology, they should copy it’s “development model”. SpaceX builds ambitious highly instrumented prototypes rapidly, that have a high risk of “failure”, with the knowledge that a crashed prototype that give you the data to build a better rocket is not a failure. This is in contrast to slow as Christmas, no risk development that ends up costing more, and delivers few advancements, but protects the jobs of bureaucrats.

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  47. There are a handful of technological ways to leapfrog SpaceX in terms of volume and mass to orbit vs. price. SABRE could help, but so could Rotating Detonation Engines or conformal aerospikes and SSTO designs using the newer materials. No need to go nuclear or photonic.

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  48. I think you exaggerate the complexity if what SpaceX is doing. The main breakthrough SpaceX achieved was breaking through the barrier of disbelief, the tech. ingredients used however were all mature. Do the Chinese have capable rocket engines? yes. Do they have control software? Yes. Do they have heat shield technology? yes. Do they have smart engineers? yes. Do they have first rate material scientists specialized in high refractory metals and ceramics? Definitely yes. So yes, they will have no problem of emulating SpaceX, just as the Europeans.

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  49. aslo because of the national security implications of space acccess theres not a chance in hell china will be able to steal space x technology like it does everything else.. they are rolling out the red carpet for tesla right now because they will steal everything from that factory and probably hope to get access to something space x.. the speed they are puting that factory up tells you everything you need to know about their real motives.. sure hope space x tech is walled off from tesla

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  50. My thoughts exactly, especially with China. I’m no rocket scientist, but I am aware that there are more efficient and powerful ways to launch loads into orbit than a chemical rocket, the nuclear thermal rocket comes to mind. We don’t use nuclear thermal because of regulatory restrictions, but if China feels they are too far behind SpaceX it seems to me they would find a way to leapfrog instead of try to play catch-up. Without being limited by the same regulatory requirements we have there would be no reason I can see why they wouldn’t. These other launch platforms you mentioned are not developed technologies, but something along these lines yes.

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  51. “…DO realize that means that China will NEVER catch up to SpaceX unless the steal the IP or buy the company right…”

    Why is that?

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  52. The problem, of course, is that they’re likely to STAY 15 years behind SpaceX on reusable rockets, unless they somehow leapfrog SpaceX to some new concept that obsoletes what Musk is doing.

    As the price leader, SpaceX will be getting most of the launch business, (They’d likely be getting all of it except for a reasonable fear of monopolies.) and they’re using each launch to feed real world test data into their development program. That’s a pretty difficult to overcome advantage, which will lead to SpaceX remaining the best reusable LOX/Methane rocket around until Musk isn’t around anymore, and the new management gets fat and happy.

    So, building yet another LOX/Methane reusable chemical booster is a fool’s game. It guarantees you’ll always be playing catch up.

    If they want to supplant Musk they have to do something new, that obsoletes what he’s doing, in the same way his reusable rockets have obsoleted disposable rockets. Laser launch, a mass driver first stage, a Lofstrom launch loop, something new and different.

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  53. They are 10-15 years behind just considering the proven SpaceX rockets the F9 and FH. If SpaceX just stopped all new developments and rested on their laurels giving up on the Starship, they are 15 years behind. With a working Starship they are 20+ years behind.

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  54. Brian you DO realize that means that China will NEVER catch up to SpaceX unless the steal the IP or buy the company right? And even if they do that will get them nothing because there were proposals on the drawing board from the 70’s that Elon could take a page from and jump ahead another decade or two. Let along taking it to the next step when he has enough capital built up. Besides these boosters are not the way to go for manned launches, although the work great for putting up cargo until we are willing to use something better.

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  55. China on the other hand has a pretty wide range of private groups rolling up soon (though many are effectively recycling military solid rocket ICBM manufacturing capability). We are far more likely to see reusability in a fairly short timespan from the liquid fueled private entrants as they are actively and openly testing right now. The big tentpole national projects/rockets usually get a Long March name, and with that is the political angle which means a much slower approach, but even that is pretty well funded.

    Though I have some serious reservations over that three stick design that’s bringing back 2 solids and a liquid in one piece, because solids are heavy. Someone joked they did that because they couldn’t get the liquid engine to throttle down enough for landing so they had to sandbag it somehow…

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  56. Considering how much begging was involved to get the purchase guarantees for Ariane 6 fulfilled to fund development, Ariane Next/Themis is going to take a while to line up funding, even if the Callisto program pans out well. Might change if there is more open JAXA involvement (JAXA RVT work is informing the design of Callisto in exchange for data access) but who knows if that will even happen. Since they are effectively national programs, the funding limits impose blessing only a small number of vehicle types currently. ESA is transitioning from Ariane 5->6 and JAXA is going from H-2 to H-3 for instance. ESA has Vega and JAXA has Epsilon, with some upgrades planned for each. Also, to a certain degree, these are make-work programs to keep the industrial base alive, so as an industry they are suffering in a minimal zombie survival mode. There’s also the far out left field possibility of Skylon, but who will build it in the mess that is Brexit? Rolls Royce is the likely airframer, which means Airbus/Arianespace is unlikely (well, REL is pretty open to who will build, but RR is the one who directly invested serious money)

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  57. I so disappointed Shenzhen makers haven’t stepped up on the reusable rocket front.
    China is the only remaining bogeyman that can get the local simpletons to act.

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