[HN Gopher] Building a rocket engine from scratch
___________________________________________________________________
Building a rocket engine from scratch
Author : sr-latch
Score : 332 points
Date : 2024-05-02 19:54 UTC (2 days ago)
(HTM) web link (blog.ablspacesystems.com)
(TXT) w3m dump (blog.ablspacesystems.com)
| datadrivenangel wrote:
| "At one point, I received a well-deserved earful from our
| machinist about how tightly spaced the turbine blades were. The
| program was taking nearly a month to run and required tiny end
| mills that broke often. We performed a turbine blade count study
| to see if we could use fewer blades with more space between them.
| It turned out the performance impact of running fewer blades was
| minimal, so we cut the number down, allowing our machinist to use
| larger, less fragile tools. Machine time dropped to less than a
| day, which was a significant win for turbine cost and machine
| time. It was also a good lesson in thinking comprehensively about
| a design's manufacturability (those passages between the blades
| looked so big on the computer screen!) in addition to its
| performance. "
|
| Once again people learn the hard way that it's valuable to have
| tight feedback cycles and embedded knowledge on your team.
| FredPret wrote:
| And also the value of a completely obsessed engineer. If the
| mech eng designing the parts is also the type to build things
| in his spare time, this type of machining problem would stand
| out right away.
|
| Of course, not everything can ever be anticipated, so tight
| feedback loops are fantastic when you can get them.
| numpad0 wrote:
| I'd agree with this take more. It's just cheaper and faster
| to just know whys and plan ahead than waiting for failures,
| if you could.
|
| I've been tinkering with 3D printers long enough that I've
| trivially halved print times after seeing long print time
| predictions. Lots of my brackets and parts fits together on
| first try and needs no supports. Rapid turnaround did help in
| _acquiring_ those skills, but now I could just waterfall
| little projects and tight looping is not that important.
| psunavy03 wrote:
| Valuing "completely obsessed" employees is a great way to
| build a company with toxic burnout culture. Some people want
| lives outside of work and are still good at their jobs.
| quartesixte wrote:
| Or some people are so good at their jobs that even while
| being completely obsessed, they still have great work-life
| balance.
|
| I interact with a lot of people like the author in the
| article from this industry. And while yes, their worklife
| balance skews "work", they all have interesting hobbies and
| find time to hang out with friends, go on adventures, and
| live a pretty full life.
|
| Unless you're on the Starship team at SpaceX. Truly, hats
| off to y'all at Boca Chica some intense hours you are
| pulling there.
| nothercastle wrote:
| Employees who are married to their job are the best
| employees. Just like in a real relationship you can treat
| them like shit and they mostly stay married
| greenish_shores wrote:
| Honestly I did read that as "Employers who are married to
| their job are the best employers". You probably won't
| treat them like shit, but they'll still remain married
| anyway.
|
| But such employees will sometimes leave and build their
| own stuff. Which they'll very likely succeed at, exactly
| because of the approach they have.
|
| Ultimately, I think these are a bit different
| fields/markets, and a bit different kind of jobs.
| Engineers creating real unique new stuff, vs more "bland"
| engineers just being a hand to accelerate someone's
| efforts. I worked in both roles and can clearly see pros
| and cons of both. Largely depends also on life phase
| one's at, which one would a person prefer.
| avmich wrote:
| > But such employees will sometimes leave and build their
| own stuff. Which they'll very likely succeed at, exactly
| because of the approach they have.
|
| Microsoft was known at some time to provide good
| environment for their engineers so they could focus on
| making the product, instead of learning the business side
| of things, which both removed distractions and reduced
| the incentives to leave and do things without well-
| learned habits.
| quartesixte wrote:
| It's a lot harder to just spin-off and "build your own
| stuff" in hardware though, which is I think what keeps
| the "married employees" around longer. The startup costs
| are much higher and riskier. And you need a lot more
| people. Building that rocket engine from scratch probably
| required around 50 - 60 people to really get it all
| together.
|
| Also, a rocket engine is a core feature of a rocket
| (literally cannot fly without it). If they started
| development of this engine in 2018, that's *six years* of
| work to get to their current state. Imagine spending 6
| years on a core feature of an app that you'd consider
| "min-viable", and everytime you had a bug the computer
| you compiled the code on spontaneously combusted?
| HeyLaughingBoy wrote:
| This was one of the main reasons why I didn't have side
| projects for a very long time. My day job was fun, and it
| scratched every itch I had. It was such an expensive
| project that I knew that I simply couldn't afford to do
| anything that would excite me that much, so I threw all
| my creative energy into the job.
|
| Eventually though, it became just a job, as it always
| does. And then the gaze turned elsewhere, looking for
| more enjoyment and satisfaction.
| guynamedloren wrote:
| This may surprise you, but it's possible to be completely
| obsessed with your work (while you're working!), while also
| maintaining a work-life balance.
| psunavy03 wrote:
| It's also a great excuse for abusing people.
| AndriyKunitsyn wrote:
| Nice read. The fact that it is possible to 3d print metal parts
| that withstand temperatures and pressures of a rocket engine is
| so exciting. How expensive is it?
| jfoutz wrote:
| Stratasys? I'm not sure about pricing, and the website won't
| say.
|
| However, a bunch of places rent out time on those machines.
| Draw up your rocket, and get a quote. Price is generally cc^2
| volume
|
| Metal is not cheap. Make a few out of plastic to verify
| dimensions.
| quartesixte wrote:
| Plastic to verify dimensions is a great approach.
|
| But don't forget that the laser sintering of metal powders
| might result in design constraints not present in plastic
| printing!
| WJW wrote:
| Mostly depends on the volume of the part, or equivalently it's
| weight. Complexity you get mostly "for free" when it comes to
| 3d printing. What type of material you need to "withstand
| temperatures and pressures of a rocket engine" is entirely
| dependent on which part of the rocket engine we're talking
| about. A fuel injector has radically different requirements
| than a supporting strut for example.
|
| 3d printed titanium goes for 300-400 USD/kg, steel is a bit
| cheaper at ~150 USD/kg for most inconel grades.
| spxneo wrote:
| side question to this: where can i design stuff involving metal
| parts (presumably in CAD tools) and have it printed en masse?
| With PCBs? ex) car components
| numpad0 wrote:
| You can draw up mechanical components in Autodesk Fusion,
| OnShape, SOLIDWORKS for Makers, or FreeCAD, and send STEP or
| STL to PCBWay or JLCPCB in China for manufacturing(note that
| export restrictions may apply if it's literal rockets or
| otherwise dual-use/controlled in nature).
|
| PCB mounting outlines can be exported from above 3D CAD and
| imported to EDA tools such as Altium and KiCAD; KiCAD is fine
| unless you're doing DRAM or PCIe. Same PCBWay and JLCPCB
| takes your design, and optionally assemble PCB with parts for
| you.
|
| That should take you to first 2-3 working units at ~$500 and
| up to few dozen beta units with zero initial cost and much
| inflated unit costs, and I guess beyond that involves
| significant human resourcing and networking problems outside
| of PoC hardware scope.
| spxneo wrote:
| thank you so much for this detailed answer. now i just need
| to invest some time into learning CAD and KiCAD
| Robelius wrote:
| You could try a battery powered phone charger since it's
| a "relatively simple" first project. The big hurdle for
| learning these types of tools is usually "What buttons do
| I press to create the output that I want.
|
| For the electrical side, there are plenty of schematics
| online that you can try to copy or use as a starting
| point. And the CAD side can be a simple box with snap
| fits. I'd recommend OnShape if you're just starting out
| since it's the lowest barrier of entry, but Fusion 360 is
| also good. All in, it should be <$150 for the PCBs +
| Components + 3D Prints.
|
| After you get the satisfaction of seeing your device
| charge from something you made, then you'll start getting
| the itch and find more excuses to make things.
| spxneo wrote:
| I'll follow your recommendation and try the simple stuff.
| Looks like OnShape is right up my alley. All very
| exciting feels like I'm "programming _hardware_ " !
| quartesixte wrote:
| And once you are done, services like Xometry allow you to
| print out the metal by having them source a printing
| vendor from their network.
| HeyLaughingBoy wrote:
| 3D printing is very popular right now. And for good reason.
| However, it often masks the fact that there are many ways to
| manufacture most products, and often, 3D printing is the most
| expensive one.
|
| Meaning that instead of thinking "how do I 3D print this?"
| you should be thinking "how do I manufacture this?"
|
| Something as simple as making a drawing, specifying the
| material and quantity needed and then going on
| reddit/r/manufacturing and asking "how would I build 50 of
| these" can provide very useful answers, even if you have to
| do a bit of research later to understand what you've been
| told.
| quartesixte wrote:
| Very. Very. Expensive.
|
| Inconel powder is also Not That Great for your health and at
| the particle-size the printers rocket companies use, you need
| full PPE to safely handle the loose powder floating about.
|
| The machines themselves are also expensive. Think in the
| millions of USD. EOS, SLM, and Velo3D are key players in this
| market. They require a fair bit of space, and training to use
| correctly.
|
| You probably need a mechanical engineer who is well-versed in
| materials science and has a tolerance for finicky machines that
| constantly breakdown.
|
| Then you have the metal powders. Which, also potential million
| or two.
|
| And then you have all the associated infrastructure needed.
| High voltage power. Gas (Nitrogen, Helium, Argon, etc etc) in
| the thousands of liters per month. Waste disposal. Safety (some
| alloys are flammable in their powder form). Climate control
| (the powders are sensitive to the environment. Humidity will
| quickly destroy your powder supply). Tooling (the base-plates
| metal printers used are machined from solid blocks of steel).
|
| And last but not least, any of the post-printing work. Heat
| treat. Coatings. Analysis. CNC Machining.
|
| 3D Printing metal on industrial scales is a CAPEX intensive
| endeavor, and not for the faint of heart.
| avmich wrote:
| Paul Breed, from Unreasonable Rocket team -
| https://x.com/unrocket - mentioned, a decade or so ago, that he
| printed some aluminum engines for regenerative cooling by
| hydrogen peroxide for ~$1000 . Another story from
| http://rocketmoonlighting.blogspot.com/2010/ is about a small
| engine cooled with nitrous oxide - and manufactured entirely on
| personal money, also quite some time ago. I think these numbers
| are still indicative of the current prices.
| quartesixte wrote:
| Aluminum is magnitudes cheaper than Inconel. And since volume
| is cubic, and pricing mostly on based on powder weight, you
| are about an order of magnitude or two off for the size of
| engine ABL is producing here.
| avmich wrote:
| That's correct, but it's still interesting that you have
| that opportunity to shave - slash? - costs here.
|
| And also the other engine mentioned isn't an aluminum one.
| aaronblohowiak wrote:
| Would $100,000 still be a "steal" for all that? (Especially
| with repeatability and nimbleness) ?
| generuso wrote:
| The material costs (the $300 per kg of titanium suggested in
| another comment) are only a small part of the overall expense.
| Electron beam sintering printer time typically costs $100-$200
| per hour, and a large build can easily take multiple days.
|
| After the printing itself, one will have to remove to loose
| powder, which for small cooling channels in the walls of the
| combustion chamber is very challenging and time consuming.
|
| After that, some post-processing may also be necessary. One
| process for achieving the greatest strength is hot isostatic
| pressing, when the part is baked in a furnace in a retort
| filled with a very high pressure inert gas.
|
| Specifically for rocket engines, it is also desirable to have a
| layer with the high heat conductivity on the inside, typically
| made of a copper-based alloy, and the external structure from a
| higher strength material. This means either bi-metallic
| printing, which is a rather niche process, or some metal
| deposition process over the printed part.
|
| In addition to this, there is usually quality control, for
| example, high resolution industrial computed tomography, to
| make sure that the invisible internal features have been
| fabricated and cleaned out correctly.
|
| In addition to the additive steps, it will also be necessary to
| machine the features which are impractical or impossible to
| build sufficiently accurately.
|
| Together, these steps add to a significant cost.
|
| Some of the above processes can be seen in this video:
| https://www.youtube.com/watch?v=7pXEf0wHU1Y
| spxneo wrote:
| now all that is required is a github for passive radar...for
| educational purposes
| sr-latch wrote:
| https://github.com/krakenrf/krakensdr_docs/wiki/
|
| The SDR world is incredible
| spxneo wrote:
| Is this the codebase that they took down ???! Yes to all of
| the things you can do (minus the passive radar stuff beyond
| educational purposes that is ;)
|
| edit: looks like they took down all the passive radar doppler
| videos :
| https://othernet.is/products/kerberossdr-4x-coherent-rtlsdr
| avmich wrote:
| Awesome story, thanks!
|
| It seems the design choices are rather conservative, which is
| entirely justified by the "from scratch" part for the first
| engine. I'm sure subsequent designs will be more bold and
| adventurous.
|
| Keep up great work!
| brcmthrowaway wrote:
| Can you use ChatGPT to build a Saturn V?
| trollerator23 wrote:
| You can try!
| brcmthrowaway wrote:
| I would get sent to jail for breaking ITAR
| trollerator23 wrote:
| I don't see how. Because ChatGPT is not from a US company?
| WalterBright wrote:
| If it's like some code I asked ChatGPT to generate, it will
| blow up on the pad!
| buescher wrote:
| NASA's report server is a national treasure, especially the
| material from the 50s and 60s that he references. Some of the
| most crisp and succinct technical writing you'll find, and you
| can infer a lot about how they ran projects. Declassified NRO
| reports are also very good - you can see the Lockheed Skunk Works
| principles in action. Example:
| https://www.nro.gov/Portals/135/documents/foia/declass/WS117...
| Horffupolde wrote:
| English is great for technical writing.
| beambot wrote:
| It probably helps that you have to be exceedingly thoughful
| about every keystroke & word less you need to completely
| retype the document or page!
| scoot wrote:
| "lest" perhaps?
|
| At least you don't have to retype the whole sentence. ;)
| mhh__ wrote:
| I'd have imagined you wrote a draft, corrected with the red
| pen, and then sent it off to (presumably) an army of women
| to do it properly.
| adrianN wrote:
| I think English has too many ambiguities to be well suited
| for technical writing. There are efforts like
| https://en.wikipedia.org/wiki/Simplified_Technical_English
| but they don't have a lot of adoption.
| trhway wrote:
| In USSR/Russia we had a stand-up comedian (Zadornov) who in
| one of his jokes was explaining how the conciseness of the
| language is advantageous on the battlefiled.
|
| Recently I had to write in Russian (my native language) a
| tech doc of many pages. That is after 26 years of tech
| writing only in English (my 2nd language). That experience
| resulted in an epiphany for me on why Russia is so
| technically behind as I suddenly understood what Zadornov
| was talking about :) In comparison to English, Russian
| sucks, to say the least, as a technical language. All the
| things which make Russian great for literature and poetry
| make it terribly inefficient for tech writing, miles and
| miles behind English. If anything, I think English is the
| secret sauce of the success of the Western technical
| civilization.
|
| (For older Russian speakers - if you remember another
| Zadornov's "dolbani pljuhalkoj po kuvykalke, prikin'sja
| vetosh'ju i ne otsvechivaj" - now I think it really comes
| from the same weakness of Russian for technical
| communication)
| z3phyr wrote:
| Th soviet mechanical and rf engineering efforts were very
| well regarded during the early cold war period, and I
| would argue, much more sophisticated. Language did not
| stop the USSR. It was the economic policy like banning
| some disciplines based on ideological grounds like
| cybernetics etc.
|
| Check it out, the things for which a western scientist or
| engineer is given credit, were discovered/invented much
| earlier by soviet counterparts! What do you think about
| Kotelnikov?
| myrmidon wrote:
| I consider the view "many discoveries were made much
| earlier by soviet counterparts" to be mostly incorrect
| and heavily biased.
|
| But it is a common and easy trap for a lot of
| nationalities to fall into, because there are innumerable
| discoveries that happen before (and/or independent of)
| the canonical "inventor" (and you're automatically more
| likely to know the independent inventors if they come
| from _your_ country!).
|
| Regarding Kotelnikov specifically: You could make the
| same argument (re: discovery of sampling theorem) for
| Whittaker, who published in 1915; ultimately, though, the
| whole debate is mostly pointless.
|
| I strongly believe that no single inventor so far was
| truly "significant", in that his nonexistence would have
| delayed science as a whole by more than a decade or two
| (consider Newton/Leibniz for calculus,
| Einstein/Poincare/Hilbert for relativity, etc.).
|
| People should not focus so much on WHO discovered a
| particular fact, because the cold truth is that it's
| mostly a personality cult and that any single scientist
| that ever existed, no matter how brilliant, was still
| replaceable (from a "human progress" kind of view). Which
| does not stop me from being a Fermi-fanboy.
|
| But I completely agree with you that language did not
| really hinder USSR science.
| randmeerkat wrote:
| > the cold truth is that it's mostly a personality cult
| and that any single scientist that ever existed, no
| matter how brilliant, was still replaceable
|
| I found the MBA.
| myrmidon wrote:
| > I found the MBA.
|
| Nope, thats a false positive.
|
| Also cutting the quote there heavily twists the meaning:
| I'm not saying those scientists were replaceable as
| persons, just that their effect on all of humanities
| scientific progress was.
|
| Many persons have a strong notion that we owe certain
| discoveries to a specific person, but this does not even
| hold up to cursory examination in my view (those
| discoveries would have been made in short order by
| someone else).
|
| I'm very curious though if you have counterexamples, or
| think the premise is otherwise flawed.
| avmich wrote:
| > I'm very curious though if you have counterexamples, or
| think the premise is otherwise flawed.
|
| I suspect we can find counterexamples if look enough,
| though to truly present some a serious knowledge of
| science history is needed.
|
| What do you think of contributions of Srinivasa Ramanujan
| and George Cantor?
| myrmidon wrote:
| I think some of Ramanujans results might have come
| significantly (more than a decade!) later without him,
| but I don't think that this would have held up
| mathematics as a field significantly.
|
| For Cantor, I think the maximum delay in results would've
| been even less, but maybe the impact (=> set theory)
| bigger during that time?
|
| I will concede that there is a lot of value that any
| specific scientist provides just from
| correspondence/communication alone which is very hard to
| quantify.
|
| I also think if you took away whole institutions from a
| hypothetical timeline, like, e.g. the University of
| Gottingen, then the impact could be quite clear (more
| than just a decade of lost progress in some field). So
| maybe you could argue that some founders of prodigious
| institutions helped human science more than any single
| scientist? But this is highly hypothetical (if the people
| AT those institutions would have existed regardless).
| Also a distasteful thought (to me).
| greedo wrote:
| Nah, it's really akin to the debate historians have over
| Great People or Inexorable events. Would calculus have
| been discovered had Liebniz and Newton died in a duel?
| Would the Panama Canal still have been built had Teddy
| Roosevelt not been its primary proponent? The Apollo
| project shows that Big Events can still happen even when
| it's most eloquent proponent gets a bullet to the head.
| randmeerkat wrote:
| > Apollo project shows that Big Events can still happen
| even when it's most eloquent proponent gets a bullet to
| the head.
|
| If Sergei Korolev didn't die suddenly and unexpectedly,
| the Soviets may have actually won the race to the moon.
| Their space program atrophied afterwards and struggled to
| succeed.
|
| I really wonder at the modern obsession with associating
| people with cattle.
| greedo wrote:
| Cattle?
| gregw2 wrote:
| I'm guessing this is a techie reference.
|
| Computer servers can be divided into two roles in modern
| technical architectures... they are either "cattle" or
| "pets". Pets are computer servers that have names and are
| always up. Cattle are servers that are transient, spun up
| and down as needed and do not necessarily have any long
| running identity/name as a component of a larger system.
|
| http://cloudscaling.com/blog/cloud-computing/the-history-
| of-...
|
| The poster is making a critiques of how by treating
| historical persons contributors as cattle, we are
| considering them a dispensable, unnamed, a commodity that
| is easily replaced and interchangeable and missing their
| very real contribution, value, and humanity.
| greedo wrote:
| I thought also that he was making the docker/container
| reference, just didn't see how it applied. Thanks for
| your expansion.
|
| I do find the Great Person theory and its critiques
| fascinating. I think of how Kennedy navigated the Cuban
| Missile Crisis and avoided nuclear war, then I think of
| how the sheer consensus of the US military after WW2 was
| to build a huge nuclear arsenal and use it any possible
| chance.
| Symmetry wrote:
| How much of it was ideological and how much of it was
| just that Gosplan didn't want computers taking their
| power, and so Gosplan cut funding to computer
| development?
| vbezhenar wrote:
| I'm Russian speaker and I don't really understand why do
| you think that Russian sucks as a technical language. The
| only reason I could imagine is that computer science
| today is full of English words, so trying to translate
| every word to Russian will result in an incomprehensible
| text, but Russian is happy to adapt words from other
| languages.
| greenish_shores wrote:
| Yeah sure. And then you have smartphone parts labelled as
| "displei + tachskrin" (to non-speakers: it's "display +
| touchscreen" written phonetically), lol. Not to say it's
| bad, though. But it's funny.
| Breza wrote:
| I wonder if it's because English adapts words from other
| languages when there's a need for a new or more concise
| phrase.
| duped wrote:
| If there's two things I've learned about chemistry from
| ExplosionsAndFire in YouTube it's
|
| - Yellow is bad
|
| - The 60s were awesome
| dotancohen wrote:
| Just yesterday I pointed out a yellow flame to someone as
| evidence of incomplete combustion on the gas stove. Laughing
| I showed them your timely comment.
|
| Out of context of the thread, your second point was amusingly
| interpreted to be about LSD.
| duped wrote:
| I'm sure a lot of the chemists making things go boom in the
| 60s were also on LSD, for what it's worth
| mhh__ wrote:
| Lots of academic and engineering things from back then are
| great.
|
| I have an incomplete set of the radlab textbooks. They're still
| useful even today, and have a really careful pace to them
| because they were written for a generation for whom electricity
| was still relatively new.
|
| One of the things that is a real shame is just how artfully
| bound those old books are. Leather, thick but smooth paper,
| etc.
| buescher wrote:
| The rad lab series basically set the program for electrical
| engineering ever since. I have a couple too. They are also
| available on archive.org.
| sr-latch wrote:
| and if you're ever writing 1DoF codes yourself, NASA's CEA for
| propellant chemistry calculations is freely available
| https://cearun.grc.nasa.gov/
| LM358 wrote:
| The executables and source code are sadly not freely
| available any more, allegedly for ITAR reasons.
| mdorazio wrote:
| Great post on building extremely complex hardware from scratch.
|
| At the same time I hate to be that business guy, but both this
| blog post and the abl site are missing a good answer to my first
| question: Why? Given that SpaceX exists and is quickly
| approaching feasibility of Starship on top of Falcon, what is the
| primary goal of this rocket system? How will it compete? Who will
| its customers be? Is it getting its metric ton payload to orbit
| faster/cheaper/easier? Is this "from scratch" engine design
| superior to existing designs in some way? What is its current
| ISP? Is Jet-A + LOX a better fuel choice given expected mission
| parameters?
|
| I'd love to see a blog post that tackles these kinds of
| questions.
| avmich wrote:
| SpaceX is certainly giving a hard time to its competitors, but
| it doesn't mean they shouldn't exist. Some of them may actually
| follow the same route, designing reusable hardware and reducing
| launch costs. SpaceX took 20 years to become relying on
| robustly reusable system; maybe some other companies reach a
| similar state sooner.
| choeger wrote:
| From the outside: Diversification is always great. Build a
| whole ecosystem of small-scale rocket manufacturers instead of
| one big monopoly. That will foster competition and innovation.
|
| From the investor: SpaceX might fail. Even if there Falcons are
| pretty much unbeatable now, you don't know what's going to
| happen with Starship. And even the Falcons could conceivably be
| grounded for years after some hypothetical flaw is found. More
| likely: With the price reductions made by SpaceX, the market
| will grow and there will be more than enough clients.
|
| From the inside: Because it's a fun challenge and literally
| rocket science, of course.
| hinkley wrote:
| SpaceX was looking to reduce prices to orbit by 10x, and they
| are currently sitting at around 6.7x.
| avmich wrote:
| I interpret this as that SpaceX has a high margin between
| market prices and their internal costs, so they can safely
| reduce prices when needed while remaining profitable. The
| competitor of course should aim not to the current prices,
| but to SpaceX's costs to be able to compete on the market.
| hinkley wrote:
| I probably over summarized. I think there's still room to
| undercut or compete (particularly on specialty projects)
| until SpaceX hits 10x for sure, and maybe as high as 15x.
| HeyLaughingBoy wrote:
| And even if there isn't, when SpaceX is booked out for
| years and you need a launch slot in 6 months, that's when
| having competition is valuable.
|
| Always look for other ways to compete besides price. (not
| intended to be as preachy as it sounds :-)
| consumer451 wrote:
| Just curious, how did you calculate the 6.7x?
| hinkley wrote:
| I found an article that declared pre-and post-SpaceX cost
| to orbit per kilogram and it was something like 18.5k
| versus 2.6k (numbers from memory).
|
| Elon before the first Dragon worked was talking about
| reducing launch costs by a factor of ten.
| Shawnj2 wrote:
| IIRC ABL's specific goal is that you can pack an entire launch
| setup into a shipping container and set one up anywhere in the
| world. Also the U.S. government will explicitly buy non SpaceX
| launch contracts specifically to keep smaller launch companies
| alive so they don't get locked into a single supplier.
| z3t4 wrote:
| The science of pressure chambers have also advanced, we could
| just pump whatever material, like liquid air into a pressure tank
| and then load it into the rocket. No mixing or pumping needed
| just open the valve and let the pressure out and you will have a
| very cheap and simple rocket.
| sr-latch wrote:
| This is absolutely not true - injector design is the most
| important aspect of designing a thrust chamber. Poor mixing of
| propellants leads to severe combustion instability, which often
| leads to explosions. Even the earliest space programs did
| significant testing on propellant choices and injector designs
| (see Ignition! by John D. Clark)
|
| Also, pressure fed rockets have always been a fairly terrible
| design. Pressure feeding requires heavy tanks, and incurs a big
| mass fraction (dry mass / wet mass) penalty. Outside of rare
| cases, it's only used for ground testing.
| z3t4 wrote:
| just drop the tank when the weight/thrust ratio is too low.
| Thanks for the book suggestion! (have not read it yet)
| quartesixte wrote:
| The rocket equation would like to have a word with you. The
| wall thicknesses required to create rockets with enough
| thrust to get to orbit on pressure-fed would render the
| rocket physically impossible.
|
| There is also a lot of control that goes into flying a
| rocket, and pressure-fed rockets are kind of hard to
| control.
| cuSetanta wrote:
| Oh wow, I work for a supplier for ABL and am today in the process
| of putting some of their stuff into our thermal chamber for
| cycling. Thats neat.
|
| We work for a lot of launcher companies, but ABL is the most
| interesting for me (even though we do relatively little for
| them). The containerised approach to the entire system is a
| really clever adaptation of existing methods to create a rapid
| launch system.
| philipwhiuk wrote:
| The jury is very much out on 'rapid'.
| criddell wrote:
| _> You might call me an unlikely candidate to lead an engine
| program from scratch, but I was hired by ABL in 2018 to do just
| that. My background was in commercial aircraft interiors, web
| development, semiconductor fab fluid components, and SpaceX
| Falcon 9 hydraulic systems._
|
| I don't mean this as an insult, but why did they hire you? It's
| obvious now that you were a great choice, but from your
| background story I wouldn't have guessed that to be true.
| quartesixte wrote:
| Seems like from the blogpost that the writer and the founder
| were part of the same cohort at SpaceX. I would hazard a guess
| that they became friends, and had planned to do this together,
| and he joined ("hired") as soon as feasible for him (or the
| founder gained enough traction to pull him away from SpaceX).
| quartesixte wrote:
| Oh and as an additional comment: Propulsion Engineers are a
| niche, specialized branch of mechanical engineers. They are
| the ones who usually design engines.
|
| The writer probably was referring to the fact that he was
| just a regular mechanical engineer and not a Propulsion
| Engineer.
| alfor wrote:
| I was wondering what is that space company and what are their
| edge with spaceX.
|
| On the site you can see: launch on demand, simple system that can
| go anywere, tactical launchs.
|
| This is for nukes or similar stuff.
| philipwhiuk wrote:
| It's not for nukes. We have silos and submarines for those.
| It's for "responsive launch" and (skeptically) because the DoD
| has lots of money for space and not much idea what to do with
| it.
|
| It's the Astra business model, hopefully without the Astra
| failure model.
|
| (And practically speaking it's because you can't bootstrap a
| heavy lift launch company on VC funding or even a SPAC - the
| small sat launcher is a proof-of-concept for your medium/large
| launch vehicle).
| hi-v-rocknroll wrote:
| Since it's 3D printed, I'm guessing from the embedded ports that
| the nozzle is hollow in parts and Jet A cooled since LOX latent
| heat of evaporation is orders of magnitude less. Probably one of
| those ports is for a temperature sensor.
| mrbluecoat wrote:
| > Example of a Clean Sheet
|
| lol, engineering humor
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