Scott, I really appreciate your science videos. I know they get a lower view count than KSP videos and you've obviously spent a lot of time in putting these together, so I understand if they have a lower "RUclips yield". That is a shame. I've learned so much about physics and astronomy through your videos. Keep up the great work.
Gigabic Yeah, that is kinda shocking. Scott spent many years at universities learning this kind of thing. While rocketry isn't his profession, I doubt many engineers are more versed in the subject than he is.
I am currently 15 and aiming for a job for NASA as an astrophysicist. Outside of school, you are my greatest help understanding this incredibly complicated subject.
Anyone read Ignition! by John Clarke? Its a must read for anyone interested in stuff like this who doesn't mind a bit of chemistry. If anything, it shows how kerbal real rocket science was in the early days. Scientist 1: Hey guys, lets mix some fluorine with molten lithium and see what it does! Scientist 2: Don't forget the hydrogen! All rockets work better with cryogenic liquid hydrogen! Scientist 1: Aww, the exhaust is so hot it's ionized and interfering with our radios. Lets try some mercury compounds next.
stevenrs11 Back before developing afterburners, they were going to add a booster rocket to fighter jets, running on jet fuel and H2O2. "Oh, what if a rat falls into the hydrogen peroxide tank? Let's test it!" But some spoilsport insisted that they just drop a rat whisker into a test tube.
+False King007 I'm thinking Nasa also has to navigate around many NDA's and security classifications as well. That makes it very hard to release material to the public... and what tidbits there are, are so scattered it's hard to collect, like what Scott did for us.
I want to see a fluorine-lithium-hydrogen rocket test now. I just can't imagine that winding up in anything other than the most spectacular and malevolent fireball mankind has ever created.
Also, at 5:00, Saturn V second and third stages used LOX and LH2 add their fuels, but they were not insulated with foam on the outside. That's why in Saturn V launches you see ice falling off the rocket when they light the engines. In Columbia, the irony is that the foam was not there to prevent evaporation, but instead to protect the orbiter. It was there to stop ice from forming on the external fuel tank which could then fall off and damage the orbiter.
angc214 From another article I read at the time, if they had used the foam they had used in the 80s before they had banned the aerosols, the foam wouldn't have broken off, and the foam wouldn't have hit the wing, preventing the crash entirely. The ozone hole scare of the 80s may have caused the crash, and we have the hippies to blame.
This was BRILLIANT !!! Your explanations are easy to understand while avoiding sounding like a dry lecture or becoming condescending. My personal fault is turning explanations into lectures, so in future rather than going that direction i'm going to give this link.
A small but important point: In a liquid hydrogen / liquid oxygen rocket, the exhaust is NOT just water. It's actually more similar to the liquid hydrogen propelled nuclear rocket, in that most of the hydrogen not burned and is therefore acting as reaction mass. Liquid hydrogen engines are always run very fuel-rich, for a couple of important reasons: 1. To reduce the burn temperature in the combustion chamber. Ok, so this is rather hot anyway, but it would be even hotter if all of the hydrogen was burned. Even using the liquid hydrogen for regenerative cooling wouldn't be enough to compensate for this. 2. To maximize the average exhaust velocity, by having as much hydrogen as possible in the exhaust. So only enough hydrogen is burned to impart heat to the rest of it, which actually increases the specific impulse. At the high temperatures used, some of the hydrogen molecules split into hydrogen atoms, which have an even higher velocity - this increases the specific impulse even further. A similar principle is used in RP1 / liquid oxygen rockets - these are also run fuel rich to reduce the burn temperature to tolerable levels. The amount of oxygen used is limited to ensure that most of the carbon in the hydrocarbon fuel burns to carbon monoxide rather than carbon dioxide. This is a lighter molecule, so has a higher exhaust velocity, boosting the specific impulse. Another modification to a rocket burning RP1 is to mix some liquid fluorine into the liquid oxygen. This causes the hydrogen component of the hydrocarbon fuel to be burned to HF rather than water. HF is a smaller and lighter molecule, so has a higher exhaust velocity than water. A liquid hydrogen engine can use liquid fluorine as the oxidizer for the same reason, and would also be run very fuel-rich.
Correct. In real world combustion, the products are never ideal, even when the inputs are stochiometric. Given a large enough population size H2 + O does not always result in H2O as just one example. Big organic molecules like RP1 produce even more varied results.
Thank you so much for the awesome science you drop on us. I wish there were more people on this planet like you. I love watching these videos because you have such awesome knowledge to give us. I can't speak for everyone, but I for one really appreciate what you do :) Plus, I learn alot.
The insulation on the ET of the Shuttle isn't there to keep the fuel from evaporating. That's a beneficial side effect, but none of the rockets before the shuttle had this and they worked just fine. The insulation is there to keep condensation ice from forming on the ET which then would rain down on the belly of the orbiter during launch destroying tiles. Watch the launch footage of the Saturn Vs and notice the tons of ice that came raining down at liftoff.
As soon as someone builds an example that can be used I'll cover it. But seriously, there will probably be a later video on 'alternative' propulsion systems.
Right there's some ideas that solid oxygen can produce a denser fuel, but density isn't a huge advantage, but I'm not a rocket fuel expert so who knows whether it's going to make a difference.
The title of this video has been in the back of my mind during every Kerbal Space Program video ever, and the entirety of my experience with it. You're doing the lords work, Scott.
yeah well you should see what happened to those German pilots in WW2 that got covered in the Methylhydrazine "STOFF" fuels...it dissolves flesh pretty well too you know....
Fluorine is such hard-core shit. it can oxidize water. Asbestos too. even Xenon 😰 also, it has no metabolic role in mammals. meaning even honey-badgers can't eat it
nachtgecher yeah it is rather the Chuck Norris of all the elements in the fucking periodic table no element will fuck with Chuck Florin Norris XD XD XD
One ion thruster that's being tested on the ISS right now uses solid metal propellant. Works well with both aluminium and magnesium, an so could use recycled satellites for orbital missions.
Thank you very much for this insightful video! I would like to have more stuff explained by you, Mir Manley, Sir. Something on reaction wheels would be nice or stage separators or maybe how trajectories are calculated...? Keep up the great work. I like KSP Videos as much as this one or the Videos about Elite or Space Citizen. Greetings from Berlin!
Opening a container of compressed gas, is a balloon right? Correct me if I am wrong but I'm pretty sure that: The container = the balloon The compressed gas = the air inside Opening the container = opening the balloon's neck to make really high pitched and annoying sounds BALLOONS IN SPACE!!!
The "Mentos in Coke" of space exploration. :) Although of course, that's not quite right because it relies on a chemical reaction, which the EVA suits didn't. It's more like playing dodgem cars in office chairs using fire extinguishers for propulsion. Or so a friend told me. ;)
One other variant of the electrical thruster is the resistojet. You get some substance, say, hydrogen, and pass it over a heating element that gets very, very hot due to massive amounts of energy being pumped into it from an external source, such as solar panels or a nuclear reactor. Much like the NTR, it benefits you to use extremely light gases for this purpose. Unlike the NTR, you don't actually need the fuel to come into physical contact with the reactor. Of course, this comes at a cost. Nuclear reactors are not usually very efficient when it comes to converting their power to electricity. Neither are solar panels, RTGs, or much else.
Ah, okay, so from a first principles standpoint, you need three things - reaction mass, energy to push that mass, and a means to do the pushing. For a chemical rocket, the energy comes from the fuel's combustion, the combustion byproducts are the reaction mass, and the pushing is done by simple thermal expansion. For a nuclear rocket, the energy comes from the heat of nuclear breakdown, a non-reactive fuel is the reaction mass, and the pushing is done, again, by simple thermal expansion. For an electric rocket, the energy comes most commonly from solar panels [but can come from an RTG too], an very inert fuel is the reaction mass, and the pushing is done by electromagnetic repulsion between the engine and the ions of the fuel. Cool beans.
Technically, only in Bi- (and other multi-)propelant rockets energy comes from combustion. In monopropelant rockets it comes from rapid decomposition in presence of catalyst.
That moment when Scott's channel I watch because I like how he plays game I like to play too, explained rocket fuels for me in detail that I've never seen anywhere else. Great work! Nasa can only dream about videos like this, even with their budget, technology and fancy effects.
But what about chlorine-trifluoride? Or was that never used? And what about fluoroantimonic acid? I heard it was planned to be used as a rocket fuel (although I'd think that was never tested, was it). I'd love to hear about those things if you know anything about them
AIUI the difficulty is it's just too damn destructive. Most organics are out because it's hypergolic with them. Flouropolymers can be used on the gas but not on the liquid because they will dissolve. Some metals can be used if they are passivated by forming a metal flouride layer but there are concerns about what happens if the passivation layer is damaged.
Lots and lots and LOTS of things were thought about, and tested in labs or in small scale test engines. Pretty much anything that could be synthesised and had decent theoretical performance. Most variations of them failed a card-gap (handling/shock stability) test by a little, or a lot, or by so much that they destroyed the apparatus (and in some cases the entire lab, with little or no warning!). Or they couldn't be stored without either destroying the storage vessel, or reacting with it and becoming contaminated, or boiling off too much at too low a temperature. Or they couldn't be handled in large quantities without insane levels of risk to life and property. Or they smelled really really bad, like "if you spill a few drops, clear the building or people will be vomiting in the hallways" kind of bad. Or they were ludicrously expensive to synthesise in the kinds of quantities required to make them useful for anything at all other than writing papers about. Bear in mind that the US military (specifically USN and USAF) paid for pretty much all early propellant development in the States before NASA was formed. They wanted bang-for-buck above all things, and the brass were not really amenable to the idea of storing large quantities of extremely volatile chemicals on aircraft carriers and airbases adjacent to similarly large quantities of fuel and ammunition (which, while hazardous, are relatively inert), nor having to train sailors and airmen in the very specific handling procedures involved. And they flatly refused to use "exotics" for any weapon which was to be stored pre-fueled, due to fears of what might happen in the event of a leak. They could be used in nice, cosy, permanently manned and maintained ICBM silos, but not on warships in the middle of the ocean. Hence the widespread use of RP-1... it came from the same refineries, they knew how to handle it because they were already using thousands of tons of gasoline, diesel and kerosene each year, it was easy to store and it had no problems with stability or boil-off. Since a whole lot of modern rocketry came out of what was learned designing and building early ICBMs and tactical missiles, we still have a lot of that older propellant technology hanging around in modern designs. But in many cases it's a matter of "if it ain't broke, don't fix it".
gdm413229 I've heard about it, it used stressed propane rings to carry extra energy compared to other isomers. It just proved too expensive compared to more conventional fuels.
+gdm413229 Basically a slightly higher performing version of Kerosene. It was used in the soviet union during the eighties, but it needs a high enough flight rate to be made profitably.
I've been wondering about that, too. The concept seems realistic enough, and starting to burn the rocket fuel at the edge of the atmosphere should yield a higher specific impulse, right?
The quick answer is that getting to orbit is about speed more than height and the atmosphere is thick and doesn't have very much oxygen in it. In fact getting into space (height) is so easy missiles fired from ships can intercept satellites, but only because they can fly really high to the satellites path and the satellite hits it, getting to orbit on the other hand is so hard only a few countries have achieved it and they are the most powerful countries in the world. Getting to orbit is hard because it requires reaching enormous speed around 27,000 kilometres per hour (21 times the speed of sound) the fastest jet EVER built could achieve mach 3, even if we could strap the space shuttle to it it would still need it's huge fuel tank to achieve orbit. It just doesn't make sense.
Jet engines are WAY less powerful and more expensive relative to thrust, however very reusable. For example the RD-180 rocket engine (for the Atlas V) produces 860,568 lbs of thrust and cost $25 million, while the GEnx-2B67 turbo fan (for the Boeing 747) produces 64,400 lbs of thrust and cost $12 million. And thrust really matters when trying to get off the ground.
7 years on and this popped up autoplay, incidentally while I had drifted off during a previous one with my ear buds in. In my somnolent haze it was as if I was sitting in front of you in a lecture room, following along every word with great intent, so much so when I woke I replayed it to find that, yup, I caught more than the gist of what you said. All's I can say is you are, and clearly always have been quite the presenter having this time taught me something subliminally in a clear and concise way Now, as far as my own 3 part fuel... what I came up with, while exiting my fugue was Peanut Butter And jelly on Heated Bread until Golden Brown. That always brings me to an excited state of energy
Something about the dual-mode RD-701 tri-propellant (LOX/RP-1/LH) would've been a nice addition to the remarks about propellant density and exhaust molecular weight... along with sea level vs. vacuum performance.
"kids might be reading and I'm a gent." Yeah. If you really wanted to be a gent. you might have used a completely different word without cursing ;) A self-censored curse word you can still guess isn't censored at all.
Excellent video scott! I liked your explanation of why nuclear rockets have a higher specific impulse then chemical rockets. I thought I would add some other obscure propellants and engine types as well: Arc-jet reactors, which use an electrical arc to vaporize a reaction-mass propellant such as butane. And pulsed plasma thrusters, which use an electrical arc to energize an inert solid propellant. Both of these are on wikipedia.
Not to hijack your question, but a functional "antimatter engine" would work similar to a nuclear engine. The device would mix equal parts of matter and antimatter, the combination of which releases pure energy (heat, light, etc...). While this would provide no thrust on its own, the energy could be used to superheat a fluid to expand, vectoring it for thrust.
Core design and cross section is one of the biggest factors related to solid rocket performance, and determining how the core will expand during burn is equally important. Look on Aerotech Rocketry's model rocket site to get a small idea of how it works, and compare the blackjack and warp 9 motor types.
I believe it has a lot to do with controlling the rate of expansion of the exhaust so that you can impart as much energy as possible to the craft. Varying the exhaust velocity and temperature allows thrust and specific impulse to be altered, usually there is a trade off due to the laws of thermodynamics and what have you.
this is fascinating please share more of your vast knowledge (as long as you are well versed in it as there is nothing worse that hearing a smart person express something they don't fully understand)
I just finished a book by Louis Friedman entitled: "Star Sailing: Solar Sails and Interstellar Flight". It mention ion engines, and states that back in the '80's (when the book was written), scientists were using argon for the Ion thrusters, but it had the same negative effects as mercury.
Alcubierre drive; cannons / mass accelerators; Project Orion; other interesting ideas that are sorta related include storing the energy off the ship - so a ship would have a large bunch of reaction mass in the back, and a ground-based laser would heat the reaction mass without the ship needing to carry a heavy source of energy.
Oooobviously, the best propellant is Staged Propellant (something I just made up right now). I suspect a good mix would be Acetylene, absorbed in Acetone, and stabilized in a foam of Paraffin wax (or bee's wax for the "Green" variant). The oxidizer side is much more simple. It's just LOX with Ozone 'Ice Cubes". The Ozone gives an extra-special kick to the Paraffin, after both materials are carefully melted, of course. It's crucial to this design to use an assortment of hypergolic starting compounds, chosen by the intensity and quality of the colors they produce upon ignition. The engine bells should also be lined with sintered Magnesium powder, for day/night visibility, and to leave a trail of cute little sparkles.
The corrosion problems with red fuming nitric acid (nitric acid with some nitrogen tetraoxide dissolved in it) was cured with the addition of a small amount of hydrogen flouride to the mix, which formed a flouride layer on the inside of the tank and protected the rest of the metal. Once that was done, they could store RFNA for years without any significant corrosion.
Radioactive materials produce a lot of energy. If there is enough, the energy sets off a chain reaction that makes too much energy which explodes and fissions it much faster. If there isn't though they just make a lot of heat. Nuclear engines don't actually use liquid fuel and oxidizer like in KSP, they just heat up something like monopropellant and spew it out. In the config file it has a note that says that the devs know it isn't realistic but didn't want to make separate types of fuel yet.
I went and looked up how it works, and I was thinking of the VASIMR. It's basically just an Ion engine where once the ions are made they're accelerated by a magnetic field to provide propulsion.
Antimatter is an incredibly challenging propulsion mechanism. The project orion method uses tech we already understand, and would simply require a few bit of clever engineering.
I've been watching your games videos for a while now and I really enjoy them, but those science videos are awesome! I love how you talk about the principles in general in a simple to understand way but still show the graphs, chemistry and math of where it comes from. Thank you!
Its just my understanding was that you had a solid chunk of fuel sitting in a container which would empty as the fuel burns creating a gap in the fuel that would lead to lower and lower pressure and in turn thrust, there for rendering the SRB essentially useless after it burns 50% of its fuel (depending on design).
@Scott Manley, not directly related to rocket fuel but as an alternitive means of combustion, I noticed the Russians in the 1960's tested an air augmented rocket with an isp of 550, the test rocket was the PR90, the production rocket was to be called the Grom, why havent other space agencies developed this for the first stage of a rocket
Project Orion, there's quite a good wiki article I think. Basically it was pretty seriously considered as an interplanetary drive. It gives both high thrust and high exhaust velocities (and thus efficiency) kind of like combining the nuclear and mainsail engines in ksp ;) Basically you can't achieve this in a normal design because it would make the internals too hot, so you throw it outside and just blow it up. I believe it was abandoned due to the test ban treaty and concerns over fallout.
Slight gripe about the energy densities. The H2 and Kerosene are not that energy dense, they just react with a tremendous amount of O2 to produce that energy. If the O2 is included, their densities are about 10 and 16, respectively. Not 46 and 123.
Hey Scott I would like to make a suggestion on a possible top and something I thought should have been in this video. There is the Nuclear Fusion Propulsion engine being developed by, I think it was a Frenchman, I can't remember but, it works by using a nuclear fusion reactor which works a bit like a partial accelerator, you know, but it then vents and channels the plasma out the back using magnets giving it an incredible power with minimal reaction mass (continued).
I only understod that "Soyaz" thing when i saw it written. It is actually pronounced "soy'ooz" (apostrophe being the stress mark, i.e. the stress is in the second sylable). Other than that - a very good video. Thank you so musch, Scott. I would give it more than 1 like if I could.
I think he's talking about the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) - it was highlighted in the mainstream media not too long ago. It does have some thermal management issues - the plasma does up to the million Kelvin range after all.
Indeed. These engines only work in-atmosphere because they require atmospheric oxygen to combust the fuels. The KSP concept of "air-hogging," throwing on preposterous amounts of intakes on a ship, exists because it allows you to "gather" more oxygen at higher altitudes. High altitudes involve low pressure atmosphere, meaning there is less and less oxygen the higher you go, so more intake surface area is required to obtain a sufficient amount of oxygen to prevent flameout.
If you're still curious about this, I cannot recommend propellant chemist John Clark's classic book Ignition! enough. It's OOP, but a PDF can be readily found with a brief search. Highlights include: a funny introduction by Issac Asimov (Clark was a SF writer as well, the two were friends), the joys of dunking a dead rat into hydrogen peroxide, and why, when your boss wants you to test dimethylmercury in your rocket, you should never sarcastically reply that you should use straight mercury.
The closest to a fusion rocket built was a model for a ship that dropped hydrogen bombs behind it to propel it. This was a project during the 50s dubbed the "Project Orion" The farthest they got was a small model that rode a few hundred feet in the air off of conventional explosives.
Great overview , I know most people looking at this video will know , but a side note: the Saturn V did use hydrogen and oxygen for the second and 3th stage and Many believe that mastering this propel and combination was key for the Americans success in the race to the moon. As you say in other video the USA only had open cycle engines.
Wheter it is a video about Kerbal Space Program or a explanation video like this. I feel like learning something interesting with every video on your Channel I watch.
It's strange looking back at this video in 2019 and seeing very little about SpaceX. "The Centaur upper stage used on all American rockets..." Amazing how quickly they've risen from virtually nothing to such a massive player.
I wish they added different fuel types to Kerbal Space Program, so that you have to balance the advantages and disadvantages of each type in your rocket design. Anyway, this is a very good introduction video to the world of rocketry, I hope lots of people see it (because from my experience, the lack of information concerning this issue among the general public is horrendous).
"Unlimited Money, Unlimited Resources, No Safety Concerns..." ...basically Kerbal Space Program in nutshells :-D
Hah.... this is what happens when you freestyle these things.
Scott, I really appreciate your science videos. I know they get a lower view count than KSP videos and you've obviously spent a lot of time in putting these together, so I understand if they have a lower "RUclips yield". That is a shame. I've learned so much about physics and astronomy through your videos.
Keep up the great work.
I think the words I'm looking for are "Hear! Hear!".
Me too!
I think it might be the opposite these days!
I'm surprised that there isn't a "Scott Manley Aerospace Co."
Actual engineers who work on this stuff know more than Scott does (shocking)
Gigabic Yeah, that is kinda shocking. Scott spent many years at universities learning this kind of thing. While rocketry isn't his profession, I doubt many engineers are more versed in the subject than he is.
hahahhhahahahahaha hahaha
Gaurav Ghosh "It isn't rocket science!"
yes,that is but Scott Manley Aerospace Co sounds so funny to me.
I am currently 15 and aiming for a job for NASA as an astrophysicist. Outside of school, you are my greatest help understanding this incredibly complicated subject.
You made this comment 7 years ago. How is that going so far?
It's been 9 yrs...
Did you do it dude?
Hope you got it chief
You're 24 now. You should be getting there
Are you still among the living?
Anyone read Ignition! by John Clarke? Its a must read for anyone interested in stuff like this who doesn't mind a bit of chemistry. If anything, it shows how kerbal real rocket science was in the early days.
Scientist 1: Hey guys, lets mix some fluorine with molten lithium and see what it does!
Scientist 2: Don't forget the hydrogen! All rockets work better with cryogenic liquid hydrogen!
Scientist 1: Aww, the exhaust is so hot it's ionized and interfering with our radios. Lets try some mercury compounds next.
Hilariously written too!
stevenrs11 oh, I loved the part where they just dumped a whole tank of F2 into the desert just to see what happens
stevenrs11 Back before developing afterburners, they were going to add a booster rocket to fighter jets, running on jet fuel and H2O2. "Oh, what if a rat falls into the hydrogen peroxide tank? Let's test it!" But some spoilsport insisted that they just drop a rat whisker into a test tube.
Ignition! has a permanent place in my library. Picked it up based on Scott’s recommendation.
Yes! So good
13:17 You had me at "Fluorine"
Yup. As soon as I read "Flourine" I thought "Done!"
If something could embody the very word ADHD it'd be Fluorine.
More info than every NASA video ever uploaded.
scheerBOM Hahah so true, i wish he would do more of these videos. This is the 2nd time im watching them...
Kurock1000 i was hoping for more videos too but there are only a few old science videos and tons of game reviews or whatever
scheerBOM I completely agree. My opinions are that either NASA expects dullards everywhere or they don't want terrorists around.
+False King007 I'm thinking Nasa also has to navigate around many NDA's and security classifications as well. That makes it very hard to release material to the public... and what tidbits there are, are so scattered it's hard to collect, like what Scott did for us.
scheerBOM Apparently, KSP nerds have never heard of Wikipedia.
I want to see a fluorine-lithium-hydrogen rocket test now. I just can't imagine that winding up in anything other than the most spectacular and malevolent fireball mankind has ever created.
Watch it fly over a forest and see the trees wilt as the exhaust hits the ground lol
Also, at 5:00, Saturn V second and third stages used LOX and LH2 add their fuels, but they were not insulated with foam on the outside. That's why in Saturn V launches you see ice falling off the rocket when they light the engines. In Columbia, the irony is that the foam was not there to prevent evaporation, but instead to protect the orbiter. It was there to stop ice from forming on the external fuel tank which could then fall off and damage the orbiter.
angc214 From another article I read at the time, if they had used the foam they had used in the 80s before they had banned the aerosols, the foam wouldn't have broken off, and the foam wouldn't have hit the wing, preventing the crash entirely. The ozone hole scare of the 80s may have caused the crash, and we have the hippies to blame.
This was BRILLIANT !!! Your explanations are easy to understand while avoiding sounding like a dry lecture or becoming condescending.
My personal fault is turning explanations into lectures, so in future rather than going that direction i'm going to give this link.
A small but important point: In a liquid hydrogen / liquid oxygen rocket, the exhaust is NOT just water. It's actually more similar to the liquid hydrogen propelled nuclear rocket, in that most of the hydrogen not burned and is therefore acting as reaction mass. Liquid hydrogen engines are always run very fuel-rich, for a couple of important reasons:
1. To reduce the burn temperature in the combustion chamber. Ok, so this is rather hot anyway, but it would be even hotter if all of the hydrogen was burned. Even using the liquid hydrogen for regenerative cooling wouldn't be enough to compensate for this.
2. To maximize the average exhaust velocity, by having as much hydrogen as possible in the exhaust. So only enough hydrogen is burned to impart heat to the rest of it, which actually increases the specific impulse. At the high temperatures used, some of the hydrogen molecules split into hydrogen atoms, which have an even higher velocity - this increases the specific impulse even further.
A similar principle is used in RP1 / liquid oxygen rockets - these are also run fuel rich to reduce the burn temperature to tolerable levels. The amount of oxygen used is limited to ensure that most of the carbon in the hydrocarbon fuel burns to carbon monoxide rather than carbon dioxide. This is a lighter molecule, so has a higher exhaust velocity, boosting the specific impulse.
Another modification to a rocket burning RP1 is to mix some liquid fluorine into the liquid oxygen. This causes the hydrogen component of the hydrocarbon fuel to be burned to HF rather than water. HF is a smaller and lighter molecule, so has a higher exhaust velocity than water. A liquid hydrogen engine can use liquid fluorine as the oxidizer for the same reason, and would also be run very fuel-rich.
Very good points here, I never went into the details of fuel mixtures, might be worth doing that at some point.
Correct. In real world combustion, the products are never ideal, even when the inputs are stochiometric. Given a large enough population size H2 + O does not always result in H2O as just one example. Big organic molecules like RP1 produce even more varied results.
Thank you so much for the awesome science you drop on us. I wish there were more people on this planet like you. I love watching these videos because you have such awesome knowledge to give us. I can't speak for everyone, but I for one really appreciate what you do :) Plus, I learn alot.
The insulation on the ET of the Shuttle isn't there to keep the fuel from evaporating. That's a beneficial side effect, but none of the rockets before the shuttle had this and they worked just fine. The insulation is there to keep condensation ice from forming on the ET which then would rain down on the belly of the orbiter during launch destroying tiles. Watch the launch footage of the Saturn Vs and notice the tons of ice that came raining down at liftoff.
As soon as someone builds an example that can be used I'll cover it.
But seriously, there will probably be a later video on 'alternative' propulsion systems.
I dont know if I commented this already.... but we Need more Videos like that, Scott :)
The first solid rocket propellant and oldest rocket fuel: black powder.
Scott, I thought I knew quit a bit about rocket fuels… I watched this three times and picked new information each time. Thanks!
Thanks Scott, I really enjoy these new videos you've been doing!
+Wes Joe new? This is from years ago :)
Oh... How embarrassing. Well I subbed long ago and it only came up today. Either way, it was very informative, thanks!
Only subbed recently, for some Kerbal-related stuff, and now I come across these. These videos are fantastic.
and now this whole thread is old
@@Diamond_Reptiles Older now
its fuel that makes the rocket go up
Slow down, not all of us went to your fancy rocket schools
it's Monday at 442AM, and your comment made my entire day already! LMAO
Might I add-
Controlled explosion: Good!
Massive shouty boom: less good, but potentially more fun.
Or go BOOOOOOM!
This is a tiny correction, but Newton's third law is equal and opposite reaction 0:47
Newton's Second law is F=ma
Fly safe!
8yrs later and I'm still learning!
the UDMH molecular structure looks like a rocket
Rocket chemical as a rocket fuel
Right there's some ideas that solid oxygen can produce a denser fuel, but density isn't a huge advantage, but I'm not a rocket fuel expert so who knows whether it's going to make a difference.
Isn't that newtons 3rd law of motion not second?
John Christy Yeah. Newton's second law is F=ma. he got that wrong
The title of this video has been in the back of my mind during every Kerbal Space Program video ever, and the entirety of my experience with it. You're doing the lords work, Scott.
Not to mention Flourine is horrifying.
yeah well you should see what happened to those German pilots in WW2 that got covered in the Methylhydrazine "STOFF" fuels...it dissolves flesh pretty well too you know....
atleast its great for your teeth :v
Fluorine is such hard-core shit.
it can oxidize water. Asbestos too. even Xenon 😰
also, it has no metabolic role in mammals. meaning even honey-badgers can't eat it
nachtgecher yeah it is rather the Chuck Norris of all the elements in the fucking periodic table no element will fuck with Chuck Florin Norris XD XD XD
You mean awesome.
One ion thruster that's being tested on the ISS right now uses solid metal propellant. Works well with both aluminium and magnesium, an so could use recycled satellites for orbital missions.
I enjoyed greatly
Wow Scott... You have reignited my passion in physics and engineering. Really amazing stuff!!!
"Reignited"
Like a friggin' ignitor
Thank you very much for this insightful video! I would like to have more stuff explained by you, Mir Manley, Sir. Something on reaction wheels would be nice or stage separators or maybe how trajectories are calculated...? Keep up the great work. I like KSP Videos as much as this one or the Videos about Elite or Space Citizen. Greetings from Berlin!
Correct! Boiling is a cooling process, which can make for some very confused looks when you can make water boil until it freezes in a pressure vessel.
So the EVA suits of the astronauts were basically like deflating a balloon in space lol.
kind of... although I would go with opening a container of compressed gas. Imagine a bottle of carbonated water that has been thoroughly shaken xD
Opening a container of compressed gas, is a balloon right? Correct me if I am wrong but I'm pretty sure that:
The container = the balloon
The compressed gas = the air inside
Opening the container = opening the balloon's neck to make really high pitched and annoying sounds
BALLOONS IN SPACE!!!
The "Mentos in Coke" of space exploration. :)
Although of course, that's not quite right because it relies on a chemical reaction, which the EVA suits didn't.
It's more like playing dodgem cars in office chairs using fire extinguishers for propulsion. Or so a friend told me. ;)
One other variant of the electrical thruster is the resistojet. You get some substance, say, hydrogen, and pass it over a heating element that gets very, very hot due to massive amounts of energy being pumped into it from an external source, such as solar panels or a nuclear reactor. Much like the NTR, it benefits you to use extremely light gases for this purpose. Unlike the NTR, you don't actually need the fuel to come into physical contact with the reactor. Of course, this comes at a cost. Nuclear reactors are not usually very efficient when it comes to converting their power to electricity. Neither are solar panels, RTGs, or much else.
Ah, okay, so from a first principles standpoint, you need three things - reaction mass, energy to push that mass, and a means to do the pushing. For a chemical rocket, the energy comes from the fuel's combustion, the combustion byproducts are the reaction mass, and the pushing is done by simple thermal expansion. For a nuclear rocket, the energy comes from the heat of nuclear breakdown, a non-reactive fuel is the reaction mass, and the pushing is done, again, by simple thermal expansion. For an electric rocket, the energy comes most commonly from solar panels [but can come from an RTG too], an very inert fuel is the reaction mass, and the pushing is done by electromagnetic repulsion between the engine and the ions of the fuel. Cool beans.
Nicely summarised.
Technically, only in Bi- (and other multi-)propelant rockets energy comes from combustion. In monopropelant rockets it comes from rapid decomposition in presence of catalyst.
That moment when Scott's channel I watch because I like how he plays game I like to play too, explained rocket fuels for me in detail that I've never seen anywhere else. Great work! Nasa can only dream about videos like this, even with their budget, technology and fancy effects.
But what about chlorine-trifluoride? Or was that never used? And what about fluoroantimonic acid? I heard it was planned to be used as a rocket fuel (although I'd think that was never tested, was it). I'd love to hear about those things if you know anything about them
Lots of things were thought about, but never flown.
Scott Manley that is true, but maybe you could make a video about the "best propulsion concepts that never propelled"
ytmoog yeah pretty much XD but there's many other great concepts like the EM drive and such
AIUI the difficulty is it's just too damn destructive. Most organics are out because it's hypergolic with them. Flouropolymers can be used on the gas but not on the liquid because they will dissolve. Some metals can be used if they are passivated by forming a metal flouride layer but there are concerns about what happens if the passivation layer is damaged.
Lots and lots and LOTS of things were thought about, and tested in labs or in small scale test engines. Pretty much anything that could be synthesised and had decent theoretical performance.
Most variations of them failed a card-gap (handling/shock stability) test by a little, or a lot, or by so much that they destroyed the apparatus (and in some cases the entire lab, with little or no warning!).
Or they couldn't be stored without either destroying the storage vessel, or reacting with it and becoming contaminated, or boiling off too much at too low a temperature.
Or they couldn't be handled in large quantities without insane levels of risk to life and property.
Or they smelled really really bad, like "if you spill a few drops, clear the building or people will be vomiting in the hallways" kind of bad.
Or they were ludicrously expensive to synthesise in the kinds of quantities required to make them useful for anything at all other than writing papers about.
Bear in mind that the US military (specifically USN and USAF) paid for pretty much all early propellant development in the States before NASA was formed. They wanted bang-for-buck above all things, and the brass were not really amenable to the idea of storing large quantities of extremely volatile chemicals on aircraft carriers and airbases adjacent to similarly large quantities of fuel and ammunition (which, while hazardous, are relatively inert), nor having to train sailors and airmen in the very specific handling procedures involved. And they flatly refused to use "exotics" for any weapon which was to be stored pre-fueled, due to fears of what might happen in the event of a leak. They could be used in nice, cosy, permanently manned and maintained ICBM silos, but not on warships in the middle of the ocean. Hence the widespread use of RP-1... it came from the same refineries, they knew how to handle it because they were already using thousands of tons of gasoline, diesel and kerosene each year, it was easy to store and it had no problems with stability or boil-off. Since a whole lot of modern rocketry came out of what was learned designing and building early ICBMs and tactical missiles, we still have a lot of that older propellant technology hanging around in modern designs. But in many cases it's a matter of "if it ain't broke, don't fix it".
If this wasn't rocket science but engineering, I think I would actually learn more in a day from you than from any of my other lecturers.
The use of "unsymmetric" instead of "asymmetric" bothers me more than it should.
stuff like this is why I don’t trust chemists
I appreciate the time and work you put into these!
Have you heard of Syntin, a Soviet/Russian rocket fuel that ended up being lost under it's own obscurity???
gdm413229 I've heard about it, it used stressed propane rings to carry extra energy compared to other isomers. It just proved too expensive compared to more conventional fuels.
scot manleyfuel
+Scott Manley that sounds incredibly fascinating!
+Scott Manley im a huge fan!!!!!! #e=mc x2
+gdm413229 Basically a slightly higher performing version of Kerosene. It was used in the soviet union during the eighties, but it needs a high enough flight rate to be made profitably.
It's very hard get all these information together and well explained. Thanks.
So why arent we using SSTOs in real life or maybe even jet engines to get the shuttle high enough for the main rocket engines to fire?
I've been wondering about that, too. The concept seems realistic enough, and starting to burn the rocket fuel at the edge of the atmosphere should yield a higher specific impulse, right?
The quick answer is that getting to orbit is about speed more than height and the atmosphere is thick and doesn't have very much oxygen in it.
In fact getting into space (height) is so easy missiles fired from ships can intercept satellites, but only because they can fly really high to the satellites path and the satellite hits it, getting to orbit on the other hand is so hard only a few countries have achieved it and they are the most powerful countries in the world.
Getting to orbit is hard because it requires reaching enormous speed around 27,000 kilometres per hour (21 times the speed of sound) the fastest jet EVER built could achieve mach 3, even if we could strap the space shuttle to it it would still need it's huge fuel tank to achieve orbit.
It just doesn't make sense.
akrebsie Thank you for the explanation sir. Take my +1 and like it!!!
Atanas Tripzter Thanks man :)
Jet engines are WAY less powerful and more expensive relative to thrust, however very reusable. For example the RD-180 rocket engine (for the Atlas V) produces 860,568 lbs of thrust and cost $25 million, while the GEnx-2B67 turbo fan (for the Boeing 747) produces 64,400 lbs of thrust and cost $12 million. And thrust really matters when trying to get off the ground.
7 years on and this popped up autoplay, incidentally while I had drifted off during a previous one with my ear buds in.
In my somnolent haze it was as if I was sitting in front of you in a lecture room, following along every word with great intent, so much so when I woke I replayed it to find that, yup, I caught more than the gist of what you said.
All's I can say is you are, and clearly always have been quite the presenter having this time taught me something subliminally in a clear and concise way
Now, as far as my own 3 part fuel... what I came up with, while exiting my fugue was Peanut Butter And jelly on Heated Bread until Golden Brown.
That always brings me to an excited state of energy
Rocket that runs on kerosene: welcome to russia
Rockets that run on alcohol...
Welcome to Russia
vodka!
Da tovarish! Za vodka!
+Joel
The RP-22 radars in the MiG-21bis were cooled by alcohol.
there are plenty of non-russian rockets that use RP1 as fuel.
Spaceship One uses a feather technique for re-entry. Much like the wing configuration you mentioned.
Newton's Second? Newton's Third.
Victor Gigante
No, no no... Who's on Second.
I dunno?
Third base!
I caught that one two
2nd law => F = ma. It results in the third. Basically the same.
Victor Gigante i was looking for someone in the comments who caught it too
Something about the dual-mode RD-701 tri-propellant (LOX/RP-1/LH) would've been a nice addition to the remarks about propellant density and exhaust molecular weight... along with sea level vs. vacuum performance.
i didn't understand a shit
Wow. I'm probably younger then you and I understand this.
how old are you?
Ello C well, if you get to an age of about 15 or so it stops being relevant for understanding stuff like this, it`s more about aptitude and education
Yes, because I assume kids might be reading and I'm a gent. Using the term 'kek', I'll assume you're no older than 12 and therefore prove my point.
"kids might be reading and I'm a gent." Yeah. If you really wanted to be a gent. you might have used a completely different word without cursing ;)
A self-censored curse word you can still guess isn't censored at all.
Man you are gifted, your explanation is easy easy to understand thank you for sharing.
Excellent video scott!
I liked your explanation of why nuclear rockets have a higher specific impulse then chemical rockets.
I thought I would add some other obscure propellants and engine types as well:
Arc-jet reactors, which use an electrical arc to vaporize a reaction-mass propellant such as butane.
And pulsed plasma thrusters, which use an electrical arc to energize an inert solid propellant.
Both of these are on wikipedia.
Not to hijack your question, but a functional "antimatter engine" would work similar to a nuclear engine. The device would mix equal parts of matter and antimatter, the combination of which releases pure energy (heat, light, etc...). While this would provide no thrust on its own, the energy could be used to superheat a fluid to expand, vectoring it for thrust.
Core design and cross section is one of the biggest factors related to solid rocket performance, and determining how the core will expand during burn is equally important. Look on Aerotech Rocketry's model rocket site to get a small idea of how it works, and compare the blackjack and warp 9 motor types.
Excellent video. Would love to see more on potential motive forces for spacecraft, solar sails etc.
I believe it has a lot to do with controlling the rate of expansion of the exhaust so that you can impart as much energy as possible to the craft. Varying the exhaust velocity and temperature allows thrust and specific impulse to be altered, usually there is a trade off due to the laws of thermodynamics and what have you.
this is fascinating please share more of your vast knowledge (as long as you are well versed in it as there is nothing worse that hearing a smart person express something they don't fully understand)
I just finished a book by Louis Friedman entitled: "Star Sailing: Solar Sails and Interstellar Flight". It mention ion engines, and states that back in the '80's (when the book was written), scientists were using argon for the Ion thrusters, but it had the same negative effects as mercury.
Another fantastic video man, keep it up. learning so much every time i watch your latest upload :)
Alcubierre drive; cannons / mass accelerators; Project Orion; other interesting ideas that are sorta related include storing the energy off the ship - so a ship would have a large bunch of reaction mass in the back, and a ground-based laser would heat the reaction mass without the ship needing to carry a heavy source of energy.
Oooobviously, the best propellant is Staged Propellant (something I just made up right now). I suspect a good mix would be Acetylene, absorbed in Acetone, and stabilized in a foam of Paraffin wax (or bee's wax for the "Green" variant). The oxidizer side is much more simple. It's just LOX with Ozone 'Ice Cubes". The Ozone gives an extra-special kick to the Paraffin, after both materials are carefully melted, of course. It's crucial to this design to use an assortment of hypergolic starting compounds, chosen by the intensity and quality of the colors they produce upon ignition. The engine bells should also be lined with sintered Magnesium powder, for day/night visibility, and to leave a trail of cute little sparkles.
This is really great !! Scott, please make more technical movies like this.
32 and still learning something every day.. Thnx Scott
The corrosion problems with red fuming nitric acid (nitric acid with some nitrogen tetraoxide dissolved in it) was cured with the addition of a small amount of hydrogen flouride to the mix, which formed a flouride layer on the inside of the tank and protected the rest of the metal. Once that was done, they could store RFNA for years without any significant corrosion.
Thank you
Radioactive materials produce a lot of energy. If there is enough, the energy sets off a chain reaction that makes too much energy which explodes and fissions it much faster. If there isn't though they just make a lot of heat. Nuclear engines don't actually use liquid fuel and oxidizer like in KSP, they just heat up something like monopropellant and spew it out. In the config file it has a note that says that the devs know it isn't realistic but didn't want to make separate types of fuel yet.
I went and looked up how it works, and I was thinking of the VASIMR. It's basically just an Ion engine where once the ions are made they're accelerated by a magnetic field to provide propulsion.
Just gonna call you Scotty. All I can see is Simon Pegg in ST. This channel is awesome, even for that by itself. :D
Antimatter is an incredibly challenging propulsion mechanism.
The project orion method uses tech we already understand, and would simply require a few bit of clever engineering.
Oh wow this is an old one. Scott congrats on having a good presentation style for all these years 👍
I feel smarter now O.O
I just went through a science video without skipping a single part :) I love your videos!
I've been watching your games videos for a while now and I really enjoy them, but those science videos are awesome! I love how you talk about the principles in general in a simple to understand way but still show the graphs, chemistry and math of where it comes from. Thank you!
Seriously this is the coolest video I've seen in ages. you rock.
Scott, you need your own show on the Science Channel. You're.that.good.
Its just my understanding was that you had a solid chunk of fuel sitting in a container which would empty as the fuel burns creating a gap in the fuel that would lead to lower and lower pressure and in turn thrust, there for rendering the SRB essentially useless after it burns 50% of its fuel (depending on design).
He did explain how that works. It is mixed with a binding agent, then pumped into the solid fuel tank where it hardens.
@Scott Manley, not directly related to rocket fuel but as an alternitive means of combustion, I noticed the Russians in the 1960's tested an air augmented rocket with an isp of 550, the test rocket was the PR90, the production rocket was to be called the Grom, why havent other space agencies developed this for the first stage of a rocket
Project Orion, there's quite a good wiki article I think. Basically it was pretty seriously considered as an interplanetary drive. It gives both high thrust and high exhaust velocities (and thus efficiency) kind of like combining the nuclear and mainsail engines in ksp ;)
Basically you can't achieve this in a normal design because it would make the internals too hot, so you throw it outside and just blow it up.
I believe it was abandoned due to the test ban treaty and concerns over fallout.
Ive learned more from this 19min video on rockets than watching 5 years of The Discovery channel.
Slight gripe about the energy densities. The H2 and Kerosene are not that energy dense, they just react with a tremendous amount of O2 to produce that energy. If the O2 is included, their densities are about 10 and 16, respectively. Not 46 and 123.
Hey Scott I would like to make a suggestion on a possible top and something I thought should have been in this video. There is the Nuclear Fusion Propulsion engine being developed by, I think it was a Frenchman, I can't remember but, it works by using a nuclear fusion reactor which works a bit like a partial accelerator, you know, but it then vents and channels the plasma out the back using magnets giving it an incredible power with minimal reaction mass (continued).
Great Scott. 9 years after. great learning
I only understod that "Soyaz" thing when i saw it written. It is actually pronounced "soy'ooz" (apostrophe being the stress mark, i.e. the stress is in the second sylable). Other than that - a very good video. Thank you so musch, Scott. I would give it more than 1 like if I could.
Oh, and yes, SRBs do tend toward a regressive thrust curve, but you can design the core to get a progressive thrust curve as well.
I think he's talking about the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) - it was highlighted in the mainstream media not too long ago. It does have some thermal management issues - the plasma does up to the million Kelvin range after all.
I had troubles with KSP modular fuels and hope to get into it by watching some more background.
Great video! Thank you.
Your videos are simply great! I enjoy every part of them not only for the science but for the excellent production that make them so interesting.
Indeed. These engines only work in-atmosphere because they require atmospheric oxygen to combust the fuels.
The KSP concept of "air-hogging," throwing on preposterous amounts of intakes on a ship, exists because it allows you to "gather" more oxygen at higher altitudes. High altitudes involve low pressure atmosphere, meaning there is less and less oxygen the higher you go, so more intake surface area is required to obtain a sufficient amount of oxygen to prevent flameout.
I found this informative and fun, although you did skip over the problem of using an unshielded nuclear reactor as a rocket motor.
If you're still curious about this, I cannot recommend propellant chemist John Clark's classic book Ignition! enough. It's OOP, but a PDF can be readily found with a brief search. Highlights include: a funny introduction by Issac Asimov (Clark was a SF writer as well, the two were friends), the joys of dunking a dead rat into hydrogen peroxide, and why, when your boss wants you to test dimethylmercury in your rocket, you should never sarcastically reply that you should use straight mercury.
The closest to a fusion rocket built was a model for a ship that dropped hydrogen bombs behind it to propel it. This was a project during the 50s dubbed the "Project Orion"
The farthest they got was a small model that rode a few hundred feet in the air off of conventional explosives.
Great walkthrough👍
Thanks for sharing 👍😀
Vary interesting had basically almost zero knowledge before hand. I now feel have good basic understanding of the subject. thanks.
This was way more interesting and informative than I thought it was going to be. Awesome job!
Great overview , I know most people looking at this video will know , but a side note: the Saturn V did use hydrogen and oxygen for the second and 3th stage and Many believe that mastering this propel and combination was key for the Americans success in the race to the moon. As you say in other video the USA only had open cycle engines.
I could listen all day of you talking.
Can I just observe that it seems Scott greatly enjoyed enlightening us here?
Your videos are always good. So entertaining!!
Wheter it is a video about Kerbal Space Program or a explanation video like this. I feel like learning something interesting with every video on your Channel I watch.
Nice vid. I really like these educational vids. You do the world a great service.
It's strange looking back at this video in 2019 and seeing very little about SpaceX. "The Centaur upper stage used on all American rockets..."
Amazing how quickly they've risen from virtually nothing to such a massive player.
It’s true, respect is due.
I wish they added different fuel types to Kerbal Space Program, so that you have to balance the advantages and disadvantages of each type in your rocket design.
Anyway, this is a very good introduction video to the world of rocketry, I hope lots of people see it (because from my experience, the lack of information concerning this issue among the general public is horrendous).
The mod CryoEngines adds liquid hydrogen/oxidizer to the standard LFO mix.