KSP Doesn't Teach: Rocket Engine Plumbing
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- Опубликовано: 9 сен 2024
- A huge part of rocket science is the system of tanks, piping, valves and burners which deliver the fuel from the tanks to the engine. I try to explain why different designs exist and the advantages that more complicated designs deliver.
To be clear, I'm not a rocket scientist, I only play one on the internet.
Rocket engine diagrams are largely from Wikipedia with some
Modification for narrative purposes
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"It worked very well, but rocket companies didn't have any incentive to continue to work upon it" - well this single sentence sums up whole rocket science development from about 1980 to about 2005.
"We can't make any money off of it, therefore we won't make newer engines."
@@falloutghoul1 Usually when that happens its because politicians cut the funding, sometimes close to completion. Happened over and over since Apollo with all kinds of promising projects. This is now finally changing since companies start doing it with a sense for profit.
Sorry to be so off topic but does anyone know a way to get back into an Instagram account??
I was dumb lost the password. I appreciate any tricks you can offer me
@Fernando Xavier thanks so much for your reply. I got to the site through google and Im trying it out now.
Takes a while so I will get back to you later when my account password hopefully is recovered.
@Fernando Xavier it worked and I now got access to my account again. Im so happy:D
Thank you so much you really help me out !
The way Apollo's first stage Rocketdyne F1 engines delt with exhaust gas from the turbopump was to blow the gas down the inside walls of the exhaust nozzle (bell) to act as a cooling film. This gas was at a lower temperature than the main rocket exhaust and insulated the nozzle. During launch you can see the gas exiting is much darker in colour than further down the exhaust stream.
Came here to say that this exact thing.
The F-1 was also ignited with hypergolic fuel, so in a matter of hundreds/thousands of a second, many valves were opening and closing in exactly the right order just to get that beast of an engine (all 5 of them) ignited and up to full thrust. Each engine had to be slightly offset in its ignition to prevent uneven stress on the vehicle as well. Despite the ignition being so complex, the F-1's still reign supreme as the kings of rocket engines.
Does the efficiency changes if complete combustion happens outside the nozzle?
Why doesn't the fuel rich turbine get sooty in the Raptor?
@@davidgray6999 I think the mixture of fuels/oxidizers they use burns pretty clean.
Very interesting. You could imagine the plumbing nightmare with 42 engines squashed in there together :)
Aye. And that's what makes me skeptical about SpaceX's craft. That's a lot of failure points. But SpaceX has a lot of clever engineers working for it, and I'm not one.
Aye. And that's what makes me skeptical about SpaceX's craft. That's a lot of failure points. But SpaceX has a lot of clever engineers working for it, and I'm not one.
arent you meant to be crewing your space station marcus. Lol
Yeap, that the soviet N1.
Well, that 12 more than the soviet N1 in fact, but you got the idea (idea that goes boom).
Still, things are a bit more advanced today and control computers and gimbaling hardware could potentially save such complex rockets from catastrophic failure (that what append to the N1, one engine failure leading to complete loss of control).
Nevertheless, what was shown in space X promo video (landing a booster on it's launchpad, then refueling and relaunching it a day after without any engine disassembly/ inspection or launchpad refurbish) is just complete bullshit ;)
Shuttle did shown that making hardware fly-worthy again is a complex and costly concept. Of course, spaceX plan is to lower cost with scale effect : more hardware to refurbish can lead to higher volume for subcontractors and a more cost-effective workflow. But that's also a problem, the more engine you'll have to work on and the more peoples you have to work with leave a lot of place for something not done right, and when something is faulty on a rocket engine, you just can't pull over the road and call for a mechanic. You goes boom. The larger the rocket is, the larger the boom is, and as the death toll (also something Shuttle sadly did learn to us)
actually that's very interesting: some super plumbers facing the same scaling-up issues as computer hardware designers.
"Explosive rocket happiness". How could I live without using that phrase so far?
Bob Ross of the Rocket Community
yah idk bro, maybe you've never ate at taco bell.
SCUBA Steve I hardly equate that type of experience with happiness.
@@badlandskid lol
That's what I also thought, I know that feeling in my head but couldn't explain it. But this "Explosive Rocket Happiness" explains it.
Absolutely understandable for not native speakers. Thanks for your work.
Yes. I sometimes have a little difficulty understanding speech, but I can always understand Scott.
There is a subtitle
Yes!
Interesting to go back and look at this after the Raptor has flown. (just not to space just yet)
ahh yes reminder it has now
The one thing I would correct is that the notion of a oxygen-rich preburn being "cooler" than a stoichiometric burn. Oxygen rich actually is a bad double-whammy: It runs hot and it introduces an oxidizer into a hot metallic system, leading to rapid disintegration. This is principally why running "lean" in car engines rapidly destroys them. The problem the Soviets found was that a fuel-rich preburn clogged the exhaust pipes and threw off the delicate flow balance into the main combustion chamber, so instead they designed turbine wheels that could survive the heat (probably the first use of Inconel turbine wheels). The space shuttle engine got around the problem by using hydrogen fuel, which has no solid byproduct. So they can run "rich" while still maintaining the flow balance.
Not to mention that running Hydrolox engines fuel rich results in a lower average molecular mass in the combustion products and increases the ISP
@@scottmanley I can't wrap my head around the idea of why a lower mass combustion product is more efficient?
Is this because there is the same combustion force/fuel reaction, so you get more "bang for your buck"?
@@JoshKaufmanstuff Lower MW gasses move at higher speeds for a given temperature. Higher exhaust velocity means higher specific impulse and more "bang for your buck"
@@JoshKaufmanstuff Isp is all about exhaust velocity. Smaller molecular mass results in higher velocicy given a fixed chamber pressure. This is why ion thrusters are so efficient, exhaust velocities in the tens of km/s
Modern KeroLOx engines seem to have sidestepped the carbonization problem possibly with better refining and design as well as more specialized materials on the fuel side.
Now I want to be a rocket plumber, mooning everyone with my space and time crack, and producing gasses which contain 7% of the fuel of the future.
I applaud you for not throwing in the obvious black hole joke in there.
+Hamachingo
Uranus
Whose anus?
Dude my mouth was open. hahaha
@@Baleur l
Hey Scott! At 6:33 you say the Merlin burns a bit of fuel and a lot of oxygen in the preburner, but it actually runs fuel rich, burning fuel with a tiny bit of oxygen, to generate gasses that are hot enough to drive the pumps but not extremely corrosive, as they would be with an oxygen rich cycle.
Can someone please explain to me why a slightly over expanded nozzle is not more efficient than an ambient nozzle (no flow Sep and higher exhaust velocity)
@@thomasrichardson8327 Over expansion means that the exhaust gas static pressure drops below ambient pressure *before* it leaves the nozzle. Basically, in an over expanded nozzle, there exists a region on the nozzle wall where the pressure exerted on the outside is stronger than the pressure exerted on the inside, which results in a net force pushing backward on the nozzle, directly reducing the total net thrust the engine produces.
@@sycodeathman That's a helpful explanation!
@@Lewlcat_ but in cases such as the sea dragon you need that giant nossle.
Love these videos Scott - starting to wish I'd done rocket science at uni and you were the lecturer!
+nockieboy I would hope I made fewer mistakes if this were my job.
Excellent presentation! It really covered a lot of material. I'm very glad you ended with the cryogenic (LH2) expander cycle and its limit (about 25,000 lb thrust), which limits the thrust of the RL-10A engine(s) of the Centaur second stage used on Atlas V. Compare this with the 210,000 lb thrust of the Merlin 1D Vacuum. The RL-10A, of course, has higher specific impulse, so it is considerably more efficient than the Merlin, but the difference in thrust means that the Centaur may have to angle its thrust to avoid falling back into the atmosphere. This is why Centaur can have one or two RL-10A engines. In the case of the Cygnus CRS OA-6 mission, the Atlas V first stage MECO'd 5 seconds too early, which meant the single engined Centaur had to burn a minute longer, using up nearly all its fuel reserves. Cygnus dropped alarmingly low back into the atmosphere, and barely made it up. All this despite the fact that the Atlas V burns a lot longer and reaches a much higher velocity and altitude than Falcon 9 at MECO. The Indians have got around the expander cycle thrust limit by building a 50,000 lb thrust class gas generator cycle cryogenic (LH2) engine for the second stage of their new GSLV 3 launcher (I say second stage, but actually the vehicle is launched with only two big SRBs firing, and the core first stage is ignited when the SRBs quit). The Delta IV second stage uses a single RL-10 engine, too.
One reason the Falcon 9 first stage is recoverable is that it quits at lower altitude and velocity, leaving the second stage with more work to do.
this has to be the most informative comment ever
Thanks Scott! This is my favorite series fo yours, it's unique and you do a great job taking really complicated concepts and breaking them down to something I can understand.
Do a video on aerospikes. How they work and why they aren't used.
hes done that
redbeam_ How long ago. I'm trying to figure out if I forgot about it or just wasn't on this channel yet
in his nozzles video (ksp doesnt teach nozzles) at 6:28
redbeam_ I meant an entire video like this dedicated to them
***** I'm just a bit obsessed with them as someone who's trying to build a hybrid rocket with one. I want to hear his take on them
A fascination-rich mixture, of clarity and technicality in equal measure.
"Explosive rocket happiness" is what this video gives me c:
Dude this series is the best
Scott, I love these videos. For a future topic, I love to hear you go a bit more In depth of nuclear thermal rockets. Last I heard if you talk about them was way early in the interstellar quest.
This is exactly what I've been looking for. I'm in the planning stage of a miniature desk rocket with a working liquid fuel engine. Now all I have to do is see how small it can be until viscosity becomes an issue.
Thank you, you steely eyed missile man!
More of this kind of stuff! Really well-explained
i really like your videos. i especially like that you just explain it in one flow as opposed to too many other people who keep cutting together 3 second clips, like after 10 words they have to go and read a script.
Love your record collection Scott.. Shows great minds are right about LPs! Thanks for the great and informative videos!
I think that is something that always been missing: Technological development in KSP. Yea sure, there is the Ion engine and the nuclear engine.
But apart from that, its mostly just larger and larger engines with different nozzles.
For example the mainsail, skipper and puddle, is reallyh one and the same engine with 3 different nozzles (giver or take)
So what do you suggest, a mini real time cfd addition, which would model the performance of geometry, describe heat flow, etc.
marshalcraft
I would like there to be one fork of nozzle research. One fork of engine (pluming) research and one fork of size research.
This way you don´t have to unlook every single engine.
Also... old pluming and nozzles out of date can become obsolete removing them from the build menu.
Also i would like to se the nozzle design as tweeks of engines in steed of different engines. This would vastly decrease the number of components to select from, making the game simpler to play, yet more functional.
Larger and more powefull engines is technological development. They are just do not say what technology is behind. How they are achived this improvement You just got final product of technolgical development/
1010ZZZ1010 Sure it is.. it was not my point. My point was that one can develop a rocket engine in 3 major ways. Better plumming, better nozile, and make it larger and still stick with the same basic idéa.
These segments videos are awesome! Keep making them. =)
Scott, these videos are excellent. Really well constructed and written, resulting in extremely informative episodes. Please keep making these!
I'm wondering about the plumbing of refueling in orbit. Has it ever been done before?
Russia does it on the ISS using the Progress. IDK if the ATV did it too.
Do you mean how do they maintain "perfect" pressure given that, as he explained, for the engine to work and not eat itself it needs near perfect ratios of fuel and oxidiser for the given rating?
I don't know. I'm not a rocket scientist/engineer, but seeing as this is the crapshoot of youtube comments I'll put my oar in.
Either they are using the same engines, and therefore have the same mix being transferred, or they have on board separate tanks that they can then inject the needed ratios into the other vehicle.
Curebores
During refueling the engines are off.
Like Andras said, the engines are off so the turbopump and the gas generator bit isnt even active. Fuel is simply being pumped into the tanks at the relatively low tank pressure via a different valve, I think thats right anyway :P
I think he means how the transfer the proper ratios (for example, etanol/LOX, one of the few ration I know, has a ratio of 7:1 in most cases). I think it is as easy as having a tank for your engines with your ratio and one for the ISS's engines with its ratio and probably different longer lasting yet probably slightly less efficient fuel (Progresses can only last about 6 months without the fuel worsening IIRC).
Hey! I know the difference between fuel rich and gas rich because I'm a welder and when you cut with an acetylene torch it requires what we call a 'neutral' flame, and not an oxidizing one.
I KNEW A THING!
as far as i know, when you cut with an acetylene torch you use the flame just to heat up the metal. when you press the lever, pure oxygen comes out of the middle nozzle and actually burns the metal, cutting it. so you cut with oxygen, basically, not with acetylene.
This is true. The more oxygen in the mix the hotter the torch. But the point is that you want a neutral flame and not an oxidizing flame
Its very very important when acetylene welding, because if you have an oxidized flame then it contaminates the weld puddle and you'll get incomplete fusion.
Welding and cutting are two different things. What I was saying is that the cutting is done by the oxygen jet alone, not by the acetylene flame, whatever the mixture. The flame is just to heat up the metal up to where the oxygen can burn it. If you could heat it up with something else like induction, you could stil cut it with oxygen. Unless you cut with the welding torch, which is not what that's designed for.
@@tripplefives1402 It's certainly true that when precision matters, you would cut metal with a plasma jet cutter or a laser, depending on the thickness of the material. (Water-jet cutters are similarly precise, but only necessary if you don't want to heat up the material being cut.) However, there are situations in demolition where all you need to do is cut a metal beam or other object in an approximate area, without any requirement for precision.
For that application, oxy-fuel cutting is still the cheapest and simplest method, either using acetylene or a substitute fuel such as MAPP gas, a blend of methylacetylene, propadiene and propylene which can be liquefied under pressure without the risk of explosive decomposition associated with acetylene.
Anyway, Dan here is entirely correct to say that welding and cutting are different: In oxy-fuel welding, you typically use a slightly fuel-rich flame (only slightly, just to ensure that the flame has no un-reacted oxygen) for heating up the weld area, and yes, this type of welding is rather imprecise compared to MIG welding, for example. Oxy-fuel cutting uses a similar flame, except it doesn't have to be fuel rich. In fact, a third gas-feed line with a separate valve is used to deliberately inject extra oxygen into the core of the flame, which really does burn the preheated metal away to make the cut.
@@tripplefives1402
No, acetylene torches *do* burn metals with pure oxygen. Pulling the trigger adds pure oxygen.
There's a great documentary on Netflix that covers the closed-cycle engine concept the Soviets developed called "Cosmodrome"
thank you very much for your time and unique content, it's heart warming to see this level of dedication to teaching science to the masses especially on subjects that have limited resources available online.
As an aeronautical engineering student, your videos are not only amazing but educational and surprisingly detailed. Just wanted to say keep up the good work!
I'm learning a lot from this video series. I always thought the liquid fuel tank on the space shuttle, for example, was just a giant bottle, not a container for machinery. I also didn't know that the rings around an exhaust nozzle were used for convection cooling. I though they were just structural.
Great video Scott I really learned a lot of things I did not know before. Any plans in the future of discussing the problems moving such high volumes of fuel through all that plumbing? I would imagine keeping laminar flow and keeping turbulence to a minimum are real engineering challenges.
That's also way beyond my knowledge of this stuff.
Thanks for responding.
Somehow, I think you could come back in a couple of days and explain it as though it was something you had known your entire life.
Seriously, how do you even explain stuff like this in such a way that almost anyone understands it? That's some serious talent and or skill, and for that, I applaud you. I have learned more about rocketry in your videos, than I ever have from anywhere else, and I've read a lot articles and books on the subjects.
Hey Scott, It was so good I watched it twice. Thank you for sharing
8:51 scott says turbo pump impellers but I think he means turbines?
good video, have a thumb up
+joinedupjon yep, I actually managed to forget the word 'turbine'
The Space Shuttle Main Engine / RS-25 cycle is fun (and I'm surprised you didn't mention it as a Full Flow engine). It uses both Pre-Combustion, with a 'leg' for each of Fuel and Oxidiser but has two pumping stages, with the Low Pressure pumps not being driven by pre-combustion. The Oxidiser side Low Pressure pump is actually driven by a tap off of the High Pressure Oxidiser and the Low Pressure Fuel pump is driven by an Expander cycle from the Fuel circuit. As you said in the video the High Pressure pumps both run off a Fuel Rich pre-combustor, however, unlike your diagram, there is no separate flow of fuel to the Combustion Chamber, all the fuel goes vis the exhausts of the pre-burners, through the turbo-pumps, and then into the engine. Oxygen arrives separately. The final little tweak is that some gaseous Hydrogen and Oxygen (as appropriate) is fed back to the tanks to pressurise them sufficiently that they don't crumple as they empty.
+Rick Ansell oh yeah the RS-25 does a lot of smart things with its plumbing. However I want to clarify that it's not considered a full flow staged combustion cycle, which is why I didn't cite it as an example of one.
I just realized that those aren't books behind him, he's got a vinyl collection
Makes me like him even more!
A friend recommended you and was fascinated to find I wasn't already watching your videos, binging through them as we speak, thank you for the informative and broad range of knowledge you have Scott!!!!
I dont usually enjoy endlessly talking people but this was good. Very nice, thanks!
I am studying astronautical engineering and we learned a tidbit about rocket engines. This video helps soo much in understanding how spacecrafts are launched. Thanks for going into the technical details that actually make sense!!
Lets make a video about flexible ducts on rocket engines, and their limitations
Hey Scott I just started working as a turbo machinery technition and I wanted to say thank you, this video really helped me understand the importance of turbo machinery and how the different types of systems work.
Hey Scott, great content as always! I must ask where do you get your information? Any books you might recommend for someone who wants to learn? Thanks.
Alp Ertuğrul Çelik Ignition! A formal history on liquid rocket propellants
I was waiting for that video for years. Thank you Scott Manley.
Those looking for fun reading should seek Ignition! An Informal History of Liquid Rocket Propellants by John D. Clark if you're not already aware of it.
I think its pretty crazy and cool that the Space Shuttle Main Engines use four turbo pumps, a low pressure and high pressure set. And it could get some pretty high performance figures while using LOX/LH2. Only downside is, you could only run it once per launch. Also, interesting you mentioned soot. I read up that the F1 rocket engine was flushed, before and after firings, and before launch, with TCE to help prevent buildup inside that would cause problems.
Could you do a video on super quick accelerating rockets like the Sprint or Gazelle missiles?
Harrison William 3 words, high TWR ratio
@@finefondue9307 Let's hope he eventually found his answer.
That was the best presentation of the various reaction-engine cycles I've seen-heard. Well done, sir.
Can you make a video about the SABRE engine?
its sortof a big jet engine but when it leaves the atmosphere it works like a rocket
@@TheRadioactiveBanana32 doesn't make much sense. Jet engines and rocket nozzle aren't any similar
There is a little error when you talk about the Turbopumps. A turbopump is a pump driven by a turbine, it is the combination of the two systems. The pumps used are usually centrifugal pumps (the impeller you show is from a centrifugal pump). So for example in the rutherford engine, the pumps are not turbopumps but electrically-driven pumps, or more specifically electrically-driven centrifugal pumps
Awesome! Can you do one on stage separation too?
Thanks for the vid Scott! Just wanted to mention, a turbo pump is already the combination of a turbine and a pump, so there is no need for an additional turbine to a turbo pump. Best, Joe
I think Project Orion should be considered once more.
***** I've heard theres a lot of it out there. You just have to build a container of antimatter to be able to keep it once it rushes through us.
Obligatory warp drive mention
I think Project Orion is a pipe dream. IMO NASA had it right before the White House stuck in the fat fingers; return to the moon, build a permanently manned base (which ironically is what China wants to do), do some more research, and then use the moon base to build and launch other, intraplanetary missions.
No.
ost355 You just have to build an antimatter container to keep it after it rushes through us? Say what?! There's no antimatter rushing through us buddy. That would be a problem. Matter + Antimatter = bad
Quite literally the most interesting video I have ever watched. Thank you for this.
I would love to see more especially as the Raptor and BE-4 mature.
Trivia: When von Braun first designed turbopump, he used the turbopump that used for high pressure fire engine at thats time
I visited the Space Museum in Leicester earlier this year with my Astronomical Society. They had a damaged turbopump assembly recovered from a V2 that fell on England, sat right next to the engine assembly (including turbopumps) from an early British sounding rocket. I'm not saying we copied the design from von Braun (we probably did), but me and another society member noticed that they looked almost completely identical...
@@dylantowers9367 You clould put a Turbocharger next to it and it would still look very similar as it's basically the same Thing. Just pumping Air instead of Liquid Fuel.
Neat stuff - I remember how cool the peroxide turbopumps on the space shuttle seemed, an elegant solution to the problem of start-up priming of those gigantic engines...the exotic materials they'd use to build all that incredibly expensive gear are another fascinating study....
is that why it's so heavily throttle-able, because you can synchronously decrease fuel flow to the pre burners?
These video literally make you smarter, thanks scott
As Dr. who would say: Clever!
Thanks Scott, this vid answers questions conveniently. Right to the point. Unlike made for tv stuff.
wait, what is the little pipe that goes down to the end of the nozzle?
I always wondered what that was
Fuel is run around the bell of an engine to cool the engine from the hot exhaust
ah thanks
It also preheats cryogenic fuel before combustion so that the fuel will reach a higher temperature in less time at combustion; a design technique called regenerative cooling.
Also in one engine design it expands the hydrogen liquid into a gas which powers the turbine that powers the fuel pumps before the engine burns it.
HuntingTarg I believe some designs do the same with oxidizer.
You could literally do full range of rocket science lectures (unrelated to KSP), you have some amazing explaining skills.
So....fuel tank + engine at the bottom. Got it.
I remember those times. Besides the fact that it was over my head back then, it is surprisingly refreshing to rewatch and get a sense of how progress happens with one of the most agile companies in the business. Also props to spacex for planning this so long ago, executing at speed and still waiting for flight 5 - and the chopstick action 😂
that thing looks more like a part of a turbocharger
+Daniel Monsanto turbocharger is exactly the same as a turbopump. Driven by exhaust gasses.
You just read some wikipedia pages :P
Now I know my truck has a bit of rocket technology in it😆😆😆
Daniel Monsanto
Your truck is a combined Otto-Brayton cycle engine.
Since he has a truck and a turbo, most likely he has a diesel. Both the Otto and Brayton engines have some sort of physical ignition system.
REALLY REALLY ENJOYED THAT !! Many thanks for the great explanations and graphics. Your brain is too cool !!
"In reality, you kinds have to make the thing work according to physics"
No, really?
Your profile pic makes this so much better xD
His profile pic?
Nah, fuck physics. Science is bullshit. **insane clown posse plays**
Lmao
Scott, Excellent video. Also, Boards of Canada Vinyl in the background?! C'mon man...You're awesome! Please keep up the excellent videos. These are extremely interesting and I can't help but continue to watch!
Wonder if Galaxy Note 7's would make a viable rocket fuel, maybe for solid boosters.
Too unpredictable and explosive 🤣
nice one 👍
I really enjoyed the educational video this time. You really helped flesh out my somewhat shallow general rocket plumbing knowledge, but I especially loved the rocket plumbing history, which I knew almost nothing about! Thanks!
now look at the starship today...
Thank you for this! Really helped me understand
I feel like the best engine will be the one with the electric turbopump. That means that 0% of the total fuel goes into forcing the fuel and the oxidizer into the combustion chamber, and instead has %100 of the fuel being burned, with all of it very pressurized.
+AP but the energy density of batteries is significantly lower than the energy density of the other fuels.
Maybe if they could use a startup battery to get it going, then generate electricity directly from the burning of the combustion chamber (kind of like how solar panels make energy from light), it would then become more efficient as the loss of energy as heat would be minimized. Of course, this is assuming that future technology permits, but only then I think would the electric solution be better. Now go ahead and prove me wrong again lol
Like a... Solar panel that operates in infrared wavelengths? I think it would suffer from the same problem as the other ones of not being able to withstand the temperatures, perhaps even more so.
Though come to think of it, the jet engines I work on have something along those lines called thermocouples. In theory, it generates electricity from thermal energy by using the properties of alumel chromel (Though I have a suspicion my tech school teacher was pulling that out of his ass as it sounds more like it simply detects temperature changes via changing resistance. I have yet to learn enough about it to tell which way it works).
Thermocouples really do generate electricity. It's how the radioisotope thermoelectric generators on many spacecraft work.
Or start them up with external power on the ground just enough to get it ticking over? obviously doesnt solve the inflight problem...
You are providing a great resource for the non rocket scientist types (like me).
Thank you
If engineers ever find out to create a reliable asparagus staging system... would credit go to the KSP community for coming up with that idea? Or has this been an existing concept in the rocket scientist world?
The concept is quite old. See Mikhail Tikhonravov; 1947. Also Vladimir Chelomei's UR-700. Both the SLS and Falcon Heavy use fuel crossfeeding. I doubt KSP-style asparagus staging would ever be used in real life due to excessive drag and complexity.
+Twan de Graaf it was conceived long before KSP
I think an asparagus staging system would cost a lot to design and recover. Considering the numerous tanks to be retrofitted and landed safely without damaging the engine or tank itself. Not only that, I have not really seen a radial stage separator on any rocket before, and what about the fuel plumbing then? Would fuel lines just be dangling inside the main booster? Or flailing about the outside? But that may be my own ignorance. I'd love to see it in real use.
Woo, thanks for your answers :), I am aware of the challenges of actually building a system like that. And yeah, with the current progress towards re-usability it probably will be a lot less significant in terms of cost and maybe when we get to the point where it would be technically feasible, we could be at a stage where the entire idea would be completely obsolete..
+Kushaal Nair space shuttle had a radial orange fuel tank. it fed fuel to the shuttle engines. had solid rocket boosters on the sides. so it's almost asparagus, just that it didn't have its own engine.
The raptor engine was the first full flow staged combustion cycle to fly. Yesterday it successfully flew on starhopper.
KSP mod request - complex engines
Or engine development
I present, realism overhaul
Thanks for the great explanation. Love your more science oriented videos please do more of these.
I remember Musk mentioning in a Q&A 1500hp electric Turbopumps that were incredibly compact given the power output. Are you sure SpaceX uses preburners at least right now?
Actually kerosene and jpg have much higher energy density, making them a logical and economical solution to store energy, opposed to lithium ion batteries which has a lower energy density. Personally I don't see any reason to uitilize battery powered turbos. May I might see an hydrogen cell or something using electricity to power the pump shaft. Maybe it could beat efficiency too. But batteries I don't think does anything better, not sure myself, I'm no rocket scientist.
I do recall that hydrogen has much higher energy density than jp5, kerosense, methane, etc. However the trade off is though hydrogen has more energy per mass, the other fuels typically have much better energy per volume at given temperature. I did some back of envelope calculations and found that l2h fueled rockets require a tank volumetric density of 195 kg/m^3 or lower to out perform jp5 as a fuel for rockets.
Aluminum has 2700 kg/m3
marshalcraft That all makes sense but I remember Musk saying turbopump though. Maybe he's still using a preburner feeds it to a generator that's separate from the electric turbopump that's meant for the fuel because he wants to avoid the issues that were mentioned by Scott in the video. Seems unlikely though as the falcon 9 is known to be pretty efficient and that would seem pretty inefficient.
+ryccoh falcon 9 has the best thrust to mass ratio but it's specific impulse is actually pretty poor compared to competitors.
Scott Manley Thanks for answering Scott, love this video series maybe you could talk about Vaccuum vs sea level engines and their differences, specifically the nozzle sizes next. Is the Falcon 9's lsp poor even compared to other RP-1 engines?
@ 06:17 Scott letts off some steam, just thinking about turbo pumps.
KSP doesn't teach: Flat Earth -theory- -hypothesis- assertion
Gekkibi wait does the flat earth theory still a thing
Yup
Alius Gigabyte
If you want to feel depressed, you only have to check Google Trends. Compare it to something equally absurd, like chemtrails and 9/11 conspiracy, and then realize it is more popular than those two put together...
You severely annoyed me for a second.
Its probably not because all those people believe in the theory, but because the flat earth theory has found new life in the public eye again with a bunch of pop artists coming out and saying they believe in it and people are curious as to what they are talking about.
I worked for Rocketdyne in the 70's as a Material and Process Engineer.
nitrogen is an inert gas?
Yes.
thx I didn't know that
not quite but pretty darn close
All gases at the most right side are Noble Gases. (Edited)
+my son unless you're lithium.... it's relatively inert
Scott, splendid explanation on the limit on size and power of ‘expander’ engines such as the RL10 imposed by the squared vs cubed relationship. It seems to me there have been a large number of permutations of rocket engine design however it also seems that such designs are undertaken in the absence of viewing the rocket as a whole. Everything is a bit of trade off. If you run RP1 and oxygen with an open cycle gas generator engine you end up with a compact (small tanks) rocket that is both cheap to develop (Falcon 9 with Merlins) and build. If you run methane with oxygen you end up with larger fuel and oxygen tanks and therefore your engine needs to be larger and, as the fuel is less dense, you need bigger and heavier fuel pumps. To compensate for this you can develop, at some cost, closed cycle engines to yield about 20% increase in efficiency. Yet with all these advances the laws of physics contrives to limit the final payload to orbit as a fraction of take off mass to about 4% for any rocket configuration. Given the questionable gains, today’s winning formula is basically one of low cost through simple design, efficient build and reuse of boosters.
0:24 "...Ellen Musk..."
Just to give an idea of the scale of some of these things, the Rocketdyne F-1 engine in the Saturn V used a gas generator cycle, where the turbopump for the fuel and oxidizer ran at 55,000 hp. That's 55 thousand horsepower, just for the pump. The engine itself produced something like 30 million horsepower.
Did you grab those rocket cycle diagrams from Wikipedia? Most of them are marked CC-BY-SA, so a citation back to the source would be good
+you238 thanks for reminding me.
No worries mate, love the videos!
+Scott Manley Just a heads up. You got a typo on that first link. Forgot the .svg :P Love your videos!
I found this video very interesting and informative. I have a mechanical engineering degree with a focus on thermal sciences. I work on turbo machinery, hydraulics and fuel systems specifically for aircraft. Over the last couple years, I've taken an interest in space exploration and all that entails. I've honestly never even looked at the applications my work would have in the space industry. I've always just looked at rockets as big engines burning stuff and making a lot of noise. It's interesting to learn just how they work and learning about the cycles is a good place to start. Thanks for the video!
Raptor, SpaceX' answer to MOAR boosterss!
thats why they want to put 42 of them on their rocket. Its a principle of could be running with less but you know, you just have to add a little bit MOAR
The SSME startup procedure is available to read online on Engine History .org (/SSME/SSME3), and it is really a remarkable thing. I think it was J. R. Thompson who joked that every twitch of a valve in the startup sequence was paid for in exploded turbopump fragments during development.
"I'm not a rocket scientist, I just play one on the internet"
Scott just dropped this line in his latest video ;)
Great video Scott, you're increasing my curiosity on this topic and it's not my background at all.
"Ellen Musk" 😂
This Musk-Guy is really a kind of Allen...
Great video! Have serious vinyl-envy now though. That is quite a collection!
Reaction Hweels
Very, very, very good automatically-generated captions (I'm deaf). 99% accurately automatically generated, even with rocket science words. Thank you!
Whenever you think of inventing something just remember, the Soviets did it first.
+LNX Gaming soviet rocket scientists blazed a trail, it's a shame soviet rocketry innovation slowed so much after the N-1
Scott Manley They definitely were pioneers. We talk about American accomplishments with the space program but we wouldent have been able to do much of what we have without the Soviets and the Germans to some extent.
***** 20 may be pushing it but pretty much my point.
nah the USA kept their Nazis, the USSR let them go after a year or so.
No not quite, Germany did it first.
I like your videos because you don''t explain things in 10 second bits. Explanations seem more realistic and lively without the cut ins, and also less annoying.
1. you say "rocket engine" when you mean "liquid fueled rocket engine". cold gas thrusters (including shaken soda bottles), monopropellant burners, solid fuel engines and hybrid rocket engines are all rocket engines. 2. the word you're looking for is "stoichiometric".
To be honest, you are right, however I think he was keeping it more simple, mainly for people who have little idea and are curious, the people who know what he is talking about are not really the target audience.
I stumbled onto this video and know nothing about rocket engines at all. This video seemed perfectly targeted for me. Everything presented clearly and i understand just a little bit more than I did about they work. The fact that they are in reality more complex than this overview presents is not a criticism.
-- Hey, he kept it "simple" and I still got lost a few times. Something I'd have to rewatch twice probably. Once to get the overview, again to see the details. Just like movies, you always miss something with the 1st view.
I really appreciate you taking time and making these videos. You’re very informative
first
Wow, thank you Sir I need more of such space tech stuff!