Is SpaceX's Raptor engine the king of rocket engines?

Is SpaceX's Raptor engine the king of rocket engines?

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Hi it's me Tim dad the everyday astronaut I'm here, at SpaceX, is brand new launch facility, in Boca Chica Texas, to, check out the, holy, grail, of rocket, engines and that SpaceX. Is upcoming, Raptor engine an engine like this has never actually been used on a rocket before now this is a methane, powered, full, flow stage, combustion, cycle engine, talking, about a rocket engines that's this complex, can be really intimidating, and in, order to put it into context, against other engines, and other engine cycles, we're gonna do a full comparison of the Raptor engine versus a bunch of other engines including, SpaceX's current workhorse the Merlin engine against, the rs.25. The Space Shuttle main engine the f1 engine that powered the Saturn 5 the, rd-180. And blue, Origins be4. That also runs on methane and as if the full flow of stage, combustion, cycle wasn't. Enough spacex, is also doing something else unique they're powering that thing with liquid, methane and that's something that's actually never been done on an orbital class rocket, so, we're gonna take a look at the characteristics, of methane and see, if we can figure out why, SpaceX, chose methane, instead. Of any other common propellant, now this engine isn't, really the best to anything, it's not the most powerful it's not the highest thrust to weight ratio of any engine it's not, even the most efficient, but it does a lot of things really. Really well. So by the end of this video hopefully, we have all the context to understand why the Raptor engine is special, how it compares to other rockets, why, it's using liquid methane and then, hopefully, we'll know if it really is the king of rocket engines let's, get started. Now. In case you didn't notice when you clicked on this video this, is a very, very. Long, video, sorry. Not, sorry but, if you're anything like me you, keep hearing a lot of hype about the Raptor engine and you want to appreciate it but you don't even know where to start well, I've spent quite a while really, studying up on the subject so I can lay down a good foundation in order to help us really truly fully appreciate, the Raptor engine well and, quite. Frankly all rocket. Engines and if you're anything like me maybe, you've stared at diagrams like this or, like this or, like this, one for hours until you feel like your head's going to explode so.

In Order to avoid that I've actually whipped up some really simple versions, of rocket engine cycles for all of us to enjoy which, will hopefully help, us grasp these crazy, concepts, but in case this isn't your first rodeo here's, the timestamps, if you want to jump to a certain section there's, also links in the description, to each section as well as an article version of this entire video at my website every, day astronaut, calm in case you want to study some of the numbers a little more in-depth or see, sources, of some of the material, now we're gonna start off with a super, quick physics, lesson but bear with me we're gonna dive in and get plenty of nitty gritty details okay so let's, start off with this rockets, are basically, just propellant. With some skin, around it to keep it in place and they, have a thing on the back that can throw said propellant, really. Really fast and to way oversimplify. It even more the, faster, you can throw, that propellant, the better now the easiest way to do this is by storing, all the propellant in your tanks under really high pressure then put, a valve on one end of the tank and a propelling, nozzle that accelerates, the propellant into workable. Thrust done. No. Crazy pumps, are complicated, systems just open, a valve and let er rip this. Is called a pressure fed rocket engine and there's a few main types cold, gas mono, prop and bipropellant pressure fed engines you'll often find these used in reaction, control systems because they're simple, reliable, and they react quickly but pressure fed engines have one big limiting, factor pressure, always, flows from high to low so, the engine can never. Be higher, pressure than the propellant, tanks in order to store propellant, under high pressure your, tanks will need to be strong, and therefore, thicker, and thicker and heavier and heavier look. At composite, overwrapped pressure, vessels or Co PVS they're, capable of storing gases, at almost, 10,000. Psi or. 700. Bar and despite this there's still a limited, amount of propellant and pressure they can store and this, does not scale, up very well when you're trying to deliver a payload to orbit so, smart rocket scientists quickly realized in order to make the rocket as lightweight as possible there's. Really only one, thing they, could do, increase. The enthalpy, that would, be a great, metal band name you're, welcome internet enthalpy, is basically, the relationship between volume pressure, and temperature. A higher. Pressure and temperature, inside the combustion chamber, equals, higher efficiency, and more, mass sub through the rocket engine equals, more thrust so in order to shove more propellant into the engine you could either increase, the pressure in the tanks or just, shoot the propellant into the combustion chamber what's a really high powered pump hmm. The second, option sounds, like a pretty good idea but, pumps moving hundreds, of liters of fuel per second, require a lot and boy. Do I mean a lot of energy to power them so, what if you took a tiny rocket, engine and aimed it right at a turbine, to, spin it up really, really fast you, can exchange some of the rocket propellants, chemical, energy for, kinetic, energy which, could then be used to spin these powerful, pumps welcome, to turbo pumps and stage combustion, cycle but. You've still got some limiting factors here like how high-pressure always wants to go to low pressure and how, he has, that habit, of melting, stuff, so. You've got to keep all these things in check while trying to squeeze every bit of power out of your engine now there's actually a lot of different variations of the cycles that we could talk about but I'm gonna stick with the three most common or, at least the three that matter the most when putting the Raptor into context, we have the gas generator cycle the, partial, flow stage combustion, cycle and lastly, we'll look at the full flow stage combustion, cycle and perhaps. In a future video I'll try and do a full rundown of all liquid, fueled rocket engines, including, fun new alternatives, like the, electric pump fed engines seen on rocket lab electron, rocket. So. Let's start with the gas generator cycle known as the open cycle this is probably one of the most common, types of liquid fueled rocket engine used on orbital, rockets it's definitely more complicated than a pressure fed system but it's fairly, simple, well. At least compared to their closed cycle counterparts. Now I'm gonna way way, oversimplify. This so it's as easy to grasp as humanly possible, in real, life there's literally dozens of, valves, a hive of wires and extra tiny little pipes everywhere helium.

To Back pressure the tanks fuel, flowing through the nozzle and the combustion chamber to cool it and there's, an ignition source for the pre burner and the combustion chamber, but again for the purpose, of making this as simple, and as digestible, as possible just know there's a lot, of stuff missing from these diagrams but, for now we're gonna focus on the flow of these engines so we can grasp that concept first. The gas generator cycle works, by pumping the fuel and oxidizer into, the combustion chamber using, a turbo pump the, turbo pump has a few main parts a mini, rocket engine called the free burner a turbine. Connected to a shaft, and then a pump or two that push propellant, into the combustion chamber now, you might hear the turbo pump assembly called the power pack because, it really, is what powers the engine in the open cycle system the spent propellant, from the pre burner is simply dumped overboard and does not contribute, any significant, thrust this, makes it less efficient, since the fuel and oxidizers, are used to spin the pumps is basically. Wasted, now the funny thing about a turbo pump is that it kind of has a chicken-and-egg, syndrome, situation, that makes it pretty difficult to, start up since the pre burner that, powers the turbo pump needs, high-pressure. Fuel and oxidizer, to operate. So the pre burner requires, the turbo pumps to spin, before, it can get up to full operational pressure, itself, but. The turbo pumps need the pre burner to fire in order to spin the turbo pumps but, the pre burner needs the turbo, pumps too yeah. You, can see where this is going this makes starting a gas generator pretty, tricky, there's a few ways to do this but we don't need to get into all that in this video that sounds like a fun topic for future videos though so back to the turbo pumps remember, pressure, always flows, from high to low so, the turbo pumps need to be a higher pressure than the chamber pressure and this, means the inlet slee to the pre burner is actually. The highest pressure point in the entire rocket engine everything. Else downstream. Is lower, pressure, but notice something here take. A look at SpaceX's merlin engine which runs on our p1 or rocket, propellant 1 and liquid, oxygen notice. How black, the smoke is coming out of the pre burner exhaust, why would it be so Sudi, compared, to the main combustion, chamber, which leaves almost no visible. Exhaust, well, that's because rocket, propellant can get super hot like. Thousands. And thousands, of degrees Celsius, so to make sure the temperature isn't so hot that it melts the turbine and the entire turbo pump assembly they, need to make sure it's cool enough to continually, operate, running. At the perfect fuel and oxidizer ratio is the most efficient, and releases the most energy, but, it also produces, a crazy, amount of heat so in order to keep the temperatures low you can run the pre burner at a less than optimal, ratio so either too much fuel known as fuel rich or too, much oxidizer, or oxygen, rich running, at our p1 engine fuel rich means you'll see some unburned, fuel appearing, as dark clouds of soot the, highly pressurized unburned, carbon molecules. Bond and form polymers, which, is a process, known as coking, this. Starts, to stick to everything, it touches and can block injectors. Or even. Do damage to the turbine itself so what if you didn't want to waste all that highly pressurized propellant, I mean after all since it's running cooler by being fuel rich doesn't.

That Mean there's a bunch, of unburned, fuel literally. Being wasted, what. If you could just pipe that hot exhaust, gas and put it into the combustion chamber huh. Welcome. To the closed cycle the, closed cycle or stage combustion cycle increases. Engine efficiency by, using what would normally be lost exhausts, and connects, it to the combustion chamber, to help increase pressure and also, increase efficiency, so let's take the merlin engine and try closing, the loop let's take the exhaust and just pipe it straight in the combustion chamber oh. No. We, just put a bunch of soot and clogged all the injectors, you, do. Not go to space today my friend but there's a few solutions to this problem so let's see how the Soviets, solved it the first operational. Close cycle engine they made was the NK, 15, designed for their n1. Rocket they later upgraded it to the NK 33, and then many versions from there stemmed out including the rd-180. Which, is what is used on the Atlas 5 today, since, the MK 15, + NK 33, runs on our p1 like the Merlin you can't run your pre-burners, fuel, rich because of the coking problem so, if you want to create a closed, cycle engine, with our p1 the, answer is running the pre burner oxygen-rich. Easy, as that right, well. Now you're blasting, superheated. Highly, pressurized gaseous. Oxygen, which, will turn just about anything into, soup right, at your precision-machined crazy, low, tolerance, turbine. Blade doing. So is actually considered, impossible, by the United States and they basically gave up on trying they. Didn't think a metal alloy existed. That could withstand these crazy, crazy, conditions. And they, didn't believe the Soviets, had made such an efficient and powerful rp1, powered engine until, after, the collapse of the Soviet Union and the, u.s. engineers got to see them and test them out firsthand but the Soviets had indeed, worked their butts off and they had made a special alloy that can magically, with, science, withstand. The crazy conditions, of an oxygen-rich, pre, burner with a closed cycle engine you don't just use some, fuel and some, oxidizer, and burn, that in the pre burner to spin the turbine you actually shoot all of, the rich propellant, through the turbine so with an oxygen rich cycle, all of the oxygen actually goes through the pre burner and just the, right amount of fuel goes to the pre burner you, only need enough to, give the turbine, the right amount of energy to spin the pumps fast enough to, get the right pressures for the pre burner and the combustion chamber, to make the right amount of power to shoot the thing into space it's, just crazy. So back, to this oxygen rich pre burner that now, hot, gaseous, oxygen is forced into the combustion chamber where, it meets liquid, fuel they, may end go boom and we get a nice clean and efficient burn without really, wasting, any propellant, but still like all engines, the chamber, pressure cannot, be higher than the pump pressure so. The pumps, actually, have a lot of weight on their tiny little metal shoulders, now if you're sitting there thinking that the United States just sat back and let the Soviets have all the closed-cycle glory you'd.

Be Wrong, it took the United it's a little bit longer but they eventually figured, out a closed cycle engine, but, it was very different from the oxygen-rich, cycle. The United States pursued a closed-loop cycle, but they went with a fuel, rich pre burner but. Wait we, just learned that fuel rich pre-burners, exhaust, is so, sooty that it pretty much ruins anything, right, well, sure if you're using rp1, or any other carbon, heavy fuel that's, definitely. Going to be the outcome so the United States went with a different, fuel. Hydrogen. Okay so now we've avoided the problem of blasting crazy hot high-pressure oxygen to anything dear and precious but. Now we've opened up a new can of worms hydrogen. Is significantly. Less dense than our p1 or liquid. Oxygen it's so, much less dense it takes a huge and really complex, turbo pump to flow the right amount of hydrogen into the combustion chamber, since our p1 and lox are relatively, similar in density, and in ratios, they, can be run on a single shaft using a single, pre burner because of this the engineers, at Rocketdyne pursued, an engine known as the rs.25. Which, would go on to power the space shuttle they, realized that because of the large difference between the pumps they, might as well have two different pre-burners, one, for the hydrogen pump and one for the oxygen pump so that's, what they did but having two separate shafts created, another, new problem now engineers, were putting high pressure hot gaseous, hydrogen on the, same shaft right. Next, door to the liquid oxygen pump, if some, of that hydrogen, would leak out of the pre burner it, would start a fire in the LOX pump which, is catastrophic. Ly, bad hydrogen, is also very, hard to contain because it's so not, dense. Undeads. Lightweight. It, likes to sneak through cracks and get out anywhere, at Ken so engineers, had to make an elaborate, seal to keep the hot hydrogen from sneaking out the seal required for this is called a purge seal and it's actually pressurized, by helium, so, that it's the highest point of pressure so if the seal leaks it just leaks inert, helium it's.

Genius But take a look at how different the LOX turbo pump and the hydrogen turbo, pump seals look you. Can tell how much more engineering time and effort had to go into the hydrogen, seals I mean, the people that think of this stuff are nuts. The rs.25, is still considered, to be about the best engine ever made with, a fairly high thrust-to-weight ratio, and unmatched, efficiency okay, now that we've talked all about the dual pre burner fuel rich rs.25, here's, a simplified, diagram of, that now, I didn't, bother making the fuel pumps different sizes and I just want to focus on the flow here and help make that as simple as possible but do note both. Pre-burners. Of the rs.25, run fuel-rich, so. Although, they might look the same they power different, pumps and I'll, just let this run here for a few seconds so you can study it for a bit but don't worry we'll also put all these up on screen at the same time once we cover them all so, the close cycle improves, the overall performance of the engine and is highly advantageous, so. How can it get any better than this we're, finally, ready to talk about the full flow stage combustion, cycle which, basically, just combines the two cycle, methods we just talked about with, the full flow stage combustion cycle you take two pre-burners, one, that runs fuel rich and one, that runs oxygen. Rich the fuel rich pre-burners, powers, the fuel pump and the oxygen, rich pre burner powers, the LOX pump this means the full flow stage combustion cycle needs to tackle the oxygen rich problems, which again, is solved. By developing, very, strong, metal alloys. So SpaceX develop their own super, alloys in-house, that they named SX, 500. According, to Elon Musk it's, capable of over 800. Bar of hot oxygen-rich, gas, that, may have been one of the biggest hurdles and developing the Raptor engine luckily, the fuel rich side only pumps, fuel so if some of that hot fuel leaks through the seal on the shaft it, just comes in contact with more fuel which, is kind of no big deal, so no need for one of those really really elaborate, seals full, flow likely, wouldn't work with our p1 due to the coking, problems with a fuel rich pre burner but, other fuels are still valid to use this design but, more, on that in a minute the advantage of the system is that since both the fuel and the oxidizer arrive in the combustion chamber as a hot gas, there's better combustion and hotter, temperatures, can be achieved there's also less of a need for that crazy sealing, system as we mentioned earlier and that's. Definitely, a good thing when you plan we use your engine over and over with little-to-no refurbishment, between flights and lastly because there's an inherent increase. In mass flow or how, quickly all the propellant, is shooting into the pre burner the, turbines, can run cooler and at, lower pressures, because the ratio of fuel and oxidizer needed. To spin the turbo pumps is much lower and think of it this way in an, open cycle you only want to use as little fuel and oxidizer as possible, in the pre-burners since it's all wasted and you, want it to be as hot as withstand, a ball to, make it more efficient, but with the full flow cycle all of the fuel and all of the oxidizer, goes through the pre-burners so, you can burn just exactly, as much propellant, as necessary, to power the turbo pumps but the cool thing is your fuel to oxidizer, ratios will be so crazy, fuel, rich and crazy. Oxygen, rich that the temperatures that the turbines will be much lower, and this, means longer lifespans, for the turbo pump assembly it also means more combustion, happens in the combustion, chamber and less, in the pre burner now here's the crazy part only, three engines, have demonstrated, the full flow stage combustion, cycle, ever.

In, The 60s the Soviets, developed an engine called the Rd 270. Which never, flew and in, the early 2000s. Aerojet, and Rocketdyne worked on an integrated, power head demonstrator, called wait, for it the integrated. Power head demonstrator, which, again, never made it past the test stand and the third attempt at developing a full flow stage combustion cycle engine is. SpaceX's. Raptor engine tada. That's, right the, Raptor engine is only the third attempt, at making this crazy type of engine it's, the first to ever do any type of work and leave a test, stand and fingers, crossed it'll be the first full flow stage combustion cycle engine, to reach orbit well. Actually just about anything this engine does will be a first this means SpaceX, had to tackle some crazy, crazy problems, I mean not only that same problem that plagues oxidizer. Rich cycles, like, having to have a really, really, strong metal alloy they, also have to learn how to control you, know two different, pre-burners, and two different cycles, to create the highest pressures. Of any chamber, pressure ever they, just beat the rd-180, s record of about 265. Bar when they 270. Bar and they're not even done they're hoping for 300. Bar inside. The combustion chamber, that's. Nuts and we'll talk more about that in a second but before we move on now that we've done a rundown on all these engine cycle types let's put them all up on screen and let them run for a bit so you can watch each one and compare them side-by-side I know for myself it helps a lot to see them all together on the same screen at the same time. Since. The Raptor engine can't run a fuel, rich pre burner using, our p1 you'd, think the next most logical choice would be hydrogen. Well, SpaceX, didn't opt for either our p1 or hydrogen. They went with liquid, methane, so now we finally, have another topic to touch on why, did SpaceX 2s liquid, methane for the Raptor engine what, are the qualities that make it advantageous, over hydrogen. Or our p1. Today. No liquid, methane or otherwise, known as methyl LOX engine has gone to orbit so, what qualities, does it have that make it desirable let's take a look at methane compared to our p1 and hydrogen. Let's put methane in between our p1 and hydrogen you'll, see why here really, quickly so let's start, off with perhaps the biggest factor when designing your first stage the, density, of the propellant having.

A Denser fuel means the tanks are smaller, and lighter for a given mass of fuel a smaller. Tank equals. A lighter rocket, so here's the density, of these three fuels measured, in grams per liter, in, other words how much does one litre of this stuff way or really. What's its mass starting. Off with our p1 one, liter is around eight hundred and thirteen grams our, p1 is 11, times more dense than hydrogen which is only 70. Grams per liter and methyl. Ox is right in the middle at 422. Grams per liter remember how airships, or Zeppelin's used to be filled with hydrogen to make them lighter, than air well. That's because hydrogen, is so much less dense than our atmosphere, it makes for an excellent albeit. Really, flammable, gas for a balloon I mean, we. All remember that Hindenburg, right it. Should also be noted that 813. Grams per liter is an average for our p1 but, SpaceX. Chills there are p1 in their Falcon 9 and Falcon Heavy for. About a 2 to 4 percent increase, in density but. Historically. Our p ones density, is right around that 813. Grams per liter so in the case of density methane is kind of right in the middle of the two others but, there's more to it than just density. We also need to take into consideration the, ratio, of how much fuel is burned compared, to how much oxidizer, is burned this is the oxidizer, to fuel ratio so. Here's where things get a little more interesting, and the tables turn just a little bit rocket. Engineers have to take into account the mass of the fuel and the corresponding, weight of the tanks so. They don't actually burn propellant, at the perfect stoichiometric combustion. Ratio, they, find the perfect happy medium that bounces, tank size with, thrust output and specific. Impulse let's look at the mass ratios for fuel and oxidizer that the engineers, have come up with so, for these numbers are p1 is burned at 2 seven grams of oxygen to, one gram of RP one hydrogen. Burns it six, grams of oxygen to one gram of hydrogen and, methane burns. At three point seven grams of oxygen to one gram of methane these numbers can now help offset a little the massive, difference in density, so, let's visualize this, to help make it easier to digest liquid. Oxygen is. 1141. Grams per liter it's, a little more dense than our p1 so burning, locks and our p1 at a two point seven to one ratio for, every liter of LOX you need a little over half a liter of our p1 next up let's do hydrogen, now with hydrogen being eleven times less, dense than our p1 you'd, think it'd need a tank that's 11, times bigger, but. Luckily, engineers. Have found that it pays to burn LOX and hydrogen, at a six to one ratio for a good compromise this means for each liter of LOX you'd need two point seven liters of hydrogen so. Your fuel tank needs to be approximately. Five times larger compared. To our p1 so, yeah that helps that's why when we look at a hydrogen powered, Delta four versus, an RP one powered Falcon nine you, can see the fuel tank is much smaller, than the LOX tank on the Falcon nine but, the Delta four is about, the opposite, the LOX tank is much, smaller, than its fuel tank so now let's take a look at methane and this one gets kind of interesting LOX, is 2.7.

Times More dense than liquid methane, but, the burn ratio is, 3.7, grams of oxygen to, one gram of methane, so, you need point seven three liters of methane for. Every liter of LOX in other words your fuel tank would need to be about, 40%. Bigger for methyl LOX than it would need to be for our p1 despite. Our p1 actually being almost twice, as dense and compared. To hydrogen its, fuel tank would be about 3.7, times, smaller, so the fuel to oxidizer, ratio helps make a methane, fuel tank a lot closer to an RP one tank than, it is to a hydrogen, tank, another, huge variable, if any rocket, engine is how efficient, it is this is measured in specific, impulse or ISP, but, you can think of it kind of like a fuel economy of a gas powered car so. A high, specific impulse would be similar, to a high mile per gallon or kilometre per liter best way to think of specific impulses, to imagine you had one kilogram, of, for. How many seconds. Can, the engine push with 9.8. Newton's of force the. Longer can sip on that fuel while still pushing that hard the, higher it's specific, impulse and therefore, the, more work it can do with the same amount of fuel so. Again kind of like it's fuel economy so the higher the specific impulse, the less fuel it takes to do the same amount of work which is a good, thing a fuel-efficient. Engine is extremely. Important, and now due to the molecular weight of each fuel and their energy released when burned there's a different, potential for how quickly the exhaust gas can be expelled out the nozzle, this, means each fuel has a different, theoretical, specific. Impulse in an ideal imperfect world an rp1 powered engine could achieve about, 370. Seconds, an ideal. Hydrogen, powered engine could get, 532. Seconds, and guess. What a methane powered engine is right in the middle with, 459, seconds, real-world, examples, of this though are much lower. With our p1 engines seeing around 350. Seconds, like the merlin 1d vacuum, around, 380, seconds, for a methane powered engine like the Raptor vacuum might be some day and about 465. Seconds, for a hydrogen powered engine like the rl10, b2, next. Let's talk about how hot, each fuel burns a fuel, that burns cooler, is easier, on the engine and potentially, makes for a longer lifespan our people one can burn up to three thousand six hundred seventy Kelvin, hydrogen. 3070. Kelvin and if, you haven't guessed it by now methane. Is again, between the two at three, thousand, five hundred fifty Kelvin, speaking, of thermal considerations, let's, look at the boiling point for each of these fuels or at what point does the liquid, fuel boil, off and turn into a gas since. All these fuels need to remain in their liquid state in order to stay dense the. Higher the temperature the easier, it is to store the fuel a higher boiling point also means less or even no insulation, on the tanks to keep the propellant, from boiling off and of course less, insulation means, lighter tanks, yay, our p1 has a very, high boiling point even. Higher than water at, 490. Kelvin, hydrogen. On the other hand is near, absolute, zero at, a crazy, cold, 20. Kelvin that's insanely. Cold and it takes serious consideration, to keep anything at that temperature and like. The Goldilocks it is methane, is between the two at 111, Kelvin, which, although that's still very cold and requires, thermal considerations, and at least boils off at a temperature similar, to locks so, there's, that and because it's so close to the temperature of locks the tanks can share a common dome which, makes the vehicle lighter, locks. And hydrogen's, temperatures vary so wildly that, locks will boil off hydrogen and the hydrogen will, freeze locks solid, now on to the exhaust what.

Are The byproducts, of combustion, with these engines rp1. Is really the only one of these three that really pollutes, with any unburnt, carbons being left in our atmosphere alongside. With some water vapor but hydrogen, only produces, water vapor and methane produces, some carbon dioxide and water vapor as well but an interesting note now believe it or not as far as greenhouse gases, go water, in the upper atmosphere can, be pretty, bad but, I'll be doing a video in the future all about how much rockets pollute talking about their air pollution also, their ocean, pollution and even space debris is a consideration, so, stand, by because I think that video is gonna be awesome, now one metric that we're just kind of going to gloss over really quick but and talk about it generally is the cost and these tend to vary considerably and, it's actually really hard to pin down the exact prices, reliably, so for. The considerations. Rp1 is basically just highly, refined jet fuel which, jet fuel is a highly refined kerosene which. Kerosene is a highly refined diesel so. It's safe to assume it's going to be more expensive than diesel hydrogen, is also relatively, expensive despite, being abundant, refining. It storing and transporting it can be hard but, methane on the other hand is basically the same thing as natural gas and can, be relatively, cheap now, when you're talking about buying literally, tons of fuel the fuel costs can add up quickly so although. The cost of fuel shouldn't factor in too much it. Certainly is a consideration, but, without hard data on this one I don't even want to put it on our chart so, instead, let's talk about the more important, aspect of the fuel that's. Manufacturing. It and here's, where we get into specifically. Why SpaceX, sees methane, as an important, or even. A necessary, part of the company's future, SpaceX, is ultimate, goals are to develop a system capable of taking, humans out to Mars and back over, and over the Martian atmosphere is, co2 rich, now combine that with water mining, from the surface and subsurface, water on Mars through, electrolysis, and the Sabatier process. The, Martian atmosphere can be made into methane fuel so, you don't have to take all the fuel you need to get home with you you can make it right there using, Mars as resources, this, is called in situ, resource utilization or, is, ru now, you might be thinking well. If there's water can't, you just make hydrogen on the surface of Mars for your fuel well, yes, but one of the biggest problems with hydrogen, and long-duration, missions, is the boiling point of hydrogen remember, it takes serious considerations. To maintain, hydrogen, in a liquid state and that's. Necessary, to be useful as a fuel so for SpaceX methane. Makes a lot of sense it's, fairly dense meaning the rocket sizes, are pretty reasonable it's, fairly efficient, it burns clean and makes, for a highly reusable engine. It burns relatively, cool helping, expand, the lifespan of an engine which again is good for usability it's, cheap and easy to produce and can. Be easily produced. On the surface of Mars. Okay. Yeah. We. Finally made it this far and now, that we have a strong, grasp of how different engine cycles operate, and the fuels they use we, can finally line them all up side-by-side and compare their metrics to help us appreciate where each engine sits so now we're going to line up each engine by their fuel type and their cycles, so let's start off with SpaceX's, open cycle Merlin edge and that powers their Falcon 9 and Falcon Heavy rockets NPO.

And Argo meshes oxygen-rich. Closed-cycle. Rd-180. That, we see power the Atlas 5 rocket and, rocket. Dines open cycle f1, that, powers a Saturn 5 which all three of these engines run on RP 1 then. We have SpaceX's. Full flow stage combustion cycle Raptor, engine that, will power the starship, and super heavy booster and then, we have blue origins close cycle oxygen-rich, methane, powered be4, engine that, will power their new Glen rocket and do Lay's upcoming, Vulcan rocket and then, we have Aerojet, Rocketdyne s, close cycle fuel. Rich rs.25. Engine that, powered the space shuttle and will power the upcoming SLS, rocket which, runs on hydrogen a few quick notes here, the Raptor and the b4 as of the making of this video are still in development so, the numbers we have here. Are either their current state of progress like, the Raptor which, is constantly, improving literally, every day and in the case of the b4, those are the target, goals for the engine which Blue Origin has yet to hit so, just, keep that in mind that these numbers are definitely subject. To change and now because of this don't forget to check in with the article, version attached in the description, of this video this, video will likely, date itself with some of these numbers and I can't update this video but. I can, update the website when, more info comes through so if you're, looking to use any of these numbers as a source, please. Please, PLEASE double check the website for any updates, another fun note quick is look at the rd-180, now don't, be confused, this is a single, engine it, just has two combustion. Chambers there's, only a single turbo, pump that splits, his power into two combustion, chambers the Soviet Union was able to solve the crazy hot oxygen-rich, closed-cycle. Problem, but, they were unable to solve combustion, instability of large engine, so, instead of one large combustion, chamber they made multiple small, ones so first up let's take a look at their total thrust output at sea level since, all these engines run at sea level that's probably a fair place to compare them let's, go from the least amount of thrust to the most for, fun the, merlin produces point 8 4 mega newtons of thrust the rs.25. Produces, 1 point 8 6 mega newtons the raptor currently is at 2 mega newtons the b4, is hoping to hit 2 point 4 mega newtons the rd-180. 3, point 8 3, mega Newtons and the, f1, is still the king out of these at six point seven 7, mega Newton's now there was an engine called the RT 170, which actually produced more thrust than the f1 but, since it barely flew, I figured it wasn't as relevant in this lineup I thought, it'd probably be a good idea to go with engines that have actually been used a lot, thrust, is great but, what's maybe just, as important when designing rocket is the thrust to weight ratio, or. How heavy the engine is compared. To how much thrust it produces, a higher, thrust, to weight ratio engine. Ultimately, means less dead weight the rocket needs to lug around let's, start from the lowest to highest here, the lowest is actually, the space shuttles rs.25. At seventy, three to one then, there's the rd-180. Which is 78 to one then, we have the b efore at around eighty to one button keep in mind we don't actually have a really good number on this so, there might be some wiggle room there then. The f1 is ninety four to one then, we have the raptor which is at about one hundred and seven to one for, now and lastly. The, merlin is actually, the leader here with an astonishing. 198. To one thrust to weight ratio, yeah. That, thing is a powerhouse, ok, thrust is great and all but who cares how powerful, an engine is if it's terribly, inefficient so. Next, up let's check out their specific, impulse which again, is measured, in seconds, so starting with the least efficient, engine which is the f1 engine at, 263. To 304. Seconds, then, the Merlin engine at 282. To, 311. Seconds. Then, we get the rd-180. At 311. Seconds, to 338. Seconds, and somewhere. In that same, ballpark is the B for which is around, 310. To, 340. Seconds, next. Up is the Raptor engine which is 330. Seconds to around 350. Seconds, and lastly. The King here by far, is the rs.25.

Which Is three hundred and sixty-six, to, four hundred and fifty-two seconds, Wow. Now. One of the factors that affect both the thrust, and specific, impulse is chamber, pressure now generally, the, higher the chamber pressure the, more thrust and potentially. More, efficient, the engine can be so. Higher, chamber, pressures let, an engine be smaller, for a given thrust level also, improving their thrust to weight ratio the baby here is actually the f1, which only had 70, bar and his chamber pressure now, I do need to pause here for a second and remind you that seventy, bar is still 70, times the atmospheric pressure or the same amount of pressure you'd experience at 700. Metres underwater. Yikes. Okay so even the lowest chamber, pressure is still mind-bogglingly. High so, next up is the Merlin engine at 97. Bar then, the b4 will be around, 135. Ish, bar then, the RS 25, which is 206. Bar then, the rd-180. Which has been considered the king of operational, engines at about. 257. Bar that is until the Raptor engine which is now kind, of online which, is considered the new king of chamber pressure at, 270. Bars currently, and they, hope to get that thing up to 300. Bar again. 300. Bars like being three, kilometers, deep in the ocean I can't. Even fathom. Okay. That's enough of the specs of these engines now. Let's look at their operational, considerations, starting, with their approximate, cost now, again and this can be kind of hard to nail down so. These are the best estimates, that I could come up with these, numbers do factor, in inflation to make them all in today's dollar though let's go with the most expensive, and work our way down to the least expensive, engineer the most expensive, engine in the lineup is the rs.25, which has a sticker price of over 50, million dollars, per engine, yikes. Then. We have the f1 which was about 30 million dollars per engine then, the rd-180, which is 25 million dollars engine then, the b4 which is around, 8 million dollars per engine and for the Raptor Elon, has mentioned he thinks he can produce the Raptor for cheaper, than or close, to the Merlin engine if they can remove a lot of the complexity, that, the current engine has so, for now we're, gonna say 2 million, dollars as a pretty decent, ballpark, then we have the Merlin engine which is less than a million I think ok well cost is one thing but another strong, consideration, for the cost of the engine is whether or not it's reusable and here, only the, rd-180. And the f1 were not reusable, or at, least never reused, which is different, than all these other engines, which, will all be reused multiple times, the, rs.25. Was reused over and over with the record being 19, flights out of a single engine well, well then again that's after a few months, of refurbishment the. Merlin is hoping to see up to 10 flights without major refurbishment we. Know a design, goal for the b4 is to be reused, up to 25 times and, I think the Raptor engine hopes to see up to 50, flights but, again, aspirations. Are one thing, we'll see how history treats these claims but one quick fun little story here is don't forget the Merlin engine which SpaceX currently uses on the Falcon 9 in Falcon Heavy Rockets are already. Fired a bunch of times before they even make it to the pad each, engine that is built goes, from Hawthorne, California to there test stand in McGregor Texas where does a full duration burn, then, those engines go back to California where, they're integrated, onto the octave web which is at the base of the vehicle then, they take the entire stage, and they take it back out to McGregor for, a full duration static, fire so it goes through the whole mission basically, again then. They ship it to the launch pad where does a short static fire and then it flies the mission so, it's already done like three, missions, in duration, of firing by the time it flies for the first time so I'm not entirely sure what the most times a single engine has done a full duration burn we, know that some of the cores were sat out on the pad and fired for a really really really long time multiple.

Times Over and over so I think they've probably done almost ten flight, full, duration burns, out of a single engine but. You know I have, no doubt they can probably do that if they say I mean they have more experience in this than anybody already, reusing. Engines without really refurbishing, them so. I'm gonna definitely take their word for it on the top of the price there's actually some things here that start to get really interesting when we started looking at these numbers the first is an interesting metric that Elon talked about once in a tweet in February of 2019, saying. They hope to make the Raptor get better at, their thrust $2, ratio, now this is a really interesting concept when you think about it who cares how much an engine costs if one big engine is cheaper than two smaller ones for the same thrust or vice versa so, let's actually take a look at the dollar to kill a Newton ratio of these engines starting, with the most expensive dollar 2 kilo Newton engine which is the rs.25, at a crazy twenty, six thousand, eight hundred eighty one dollars two kilonewtons, of thrust then. The rd-180. Which is six, thousand, five hundred twenty seven dollars to one kilonewton, followed, by the f1, at. 4431. Dollars. Per kilonewton, and then, we get to the b 4, which is. 3333. Dollars to one kilonewton, the merlin engine at, 1170. Dollars per kilonewton, and the raptor at around one thousand, dollars per kilonewton, but now we can go even another step further since we know their dollar two kilonewton, ratio but, we also know, their reusability. Potential. Now, we can predict their potential, cost per kilonewton, per flight, which. Changes, based on how reusable, these engines actually are so, for starters since the rd-180, and the f1 aren't reusable, their price stays the same but, for the rest of the engines if we take into account how many flights they have slash, will have now, we start to see the rs.25. Reusability, pay off and kind, of close the gap bringing, its potential, cost down to just one, thousand, four hundred fourteen, dollars per kilonewton, per flight, but, here's where things get crazy blue. Origins b4, has potential, to truly, be game-changing and around one hundred and thirty three dollars per kilonewton, over, twenty five flights which, could make it about as cheap to operate as the merlin at one hundred and seventeen, dollars per kilonewton, per flight but, if the raptor engine truly, lives up to its hype it, could bring this number all the way down to $20. Per kilonewton, per flight, now. That is absolutely, game-changing. Sir money, and reusability, is a 21st, century focus for space flight but whatever HAP - good old proven, reliability, for. This let's, first look at how many operational, flights each engine has had not at the moment of shooting this video the Raptor and b4 haven't seen any operational. Flights, although, the Raptor is starting to leave the test stand and is being used on test vehicles like the star hopper but, for now neither, engine has a real, flight record so let's look at the other engines, first we have the f1 engine which was used on 17, flights next. Up is the Merlin engine which is at 71, flights and catching up quickly to the rd-180, which is at 79, flights but the king out of these was the rs.25. Which saw a hundred, and thirty-five flights, now lastly, how about reliability. And service between, the number of flights and this number we, can get a pretty good sense of how truly, reliable an engine is this. Number is really hard to just pin down since some of the engines may have shut down early, but, the mission was still a success on, a few of these so yes. It take a few of these with a grain of salt again the b4, and Raptor engine haven't flown yet so those numbers are unavailable, then. We have this Space Shuttle main engine which is over. 99.5%. Reliable. But, that gets hard to define when an engine doesn't fully, shut down and, then we have the Merlin at 99.9. Percent reliable it, sure helps when you have 10 engines, on each flight of the vehicle and with, only one engine ever failing, early on in his career and despite. That that mission was still a success so, the. Merlin is a very. Reliable, engine, now to end this technically, the rd-180. And the f1 are 100%. Reliable, but, with the f1, never having shutdown at all in any flight it gets the bold here, and depending, on how you define success and, reliability, technically.

The Rd-180. Is only kind. Of 100, percent reliable because, it got really, lucky once one time it shut down six, seconds, early on an Atlas five mission in 2016. This was due to a faulty, valve but, the mission went on to be a success, because, of some pure luck with, the Centaur upper stage having, enough spare delta-v to, carry out the mission had, that Valve failed even a second, earlier that. Mission would, have failed. Man, seeing all these numbers and considerations. It makes you realize just how, many variables, go into designing, rocket I mean change any one little, thing and it can have this massive ripple, effect on the entire design and the, implementation, of the vehicle as a whole so let's go back over all of this now that we know all the cycles, the fuels the aspirations, of SpaceX to see if we can figure out why the Raptor, engine exists, and figure. Out if it's worth all the effort let's, look at space X's ultimate plan make, a rapidly. And fully reusable vehicle. Capable of sending humans to the Moon and Mars as, inexpensively. And routinely as possible, it's. Not exactly, your everyday goal for a rocket huh in order to be rapidly, and fully reusable the, engine, needs to run clean and require, low maintenance with simple, turbo, pump seals and low, prerunner temperatures, hmm. A methane. Fueled full flow staged combustion, cycle engine sounds, like a good fit for reliability. Redundancy and, scale of manufacturing, considerations, it makes sense to employ a lot of engines, in order to scale an engine down but maintain, a high output chamber. Pressure needs to be high hmm. Sounds. Like a methane, fueled full flow stage combustion cycle engine is a good fit for interplanetary trips, methane, makes the most sense because it's boiling point makes, it usable on long-duration trips, to Mars which, guess what you, can produce methane. On Mars so for interplanetary, trips, a methane. Fueled full flow stage combustion cycle engine sounds, like a good fit methane is fairly, dense meaning, the tank size remains reasonable, which again is good for interplanetary, trips not, needing to lug around a lot of deadweight, making.

A Methane, fueled full flow stage combustion, cycle a, pretty good fit, okay, so let's, bring this all back around, now is the. Raptor engine really, the king of rocket engines, well, rocket. Science, like all things is a complex, series of compromises is it, the most efficient, engine no. Is it, the most powerful, engine no, is, it the cheapest engine probably, not is it, the most reusable, engine maybe, but does it do everything really well yeah. It is truly a Goldilocks, engine, doing everything it needs to do very very well it is, the perfect fit for your interplanetary. Spaceship, and despite, its complexity, SpaceX, is developing this engine at a rapid, pace I mean, knowing how much tweaking, SpaceX, did to their Merlin engine over a decade we're, just at the infancy, of the Raptor engine it's only gonna get better from here on out which, is crazy. So, all in all the Raptor engine is the, king of this. Application. It's a fantastic, engine to fulfill SpaceX's, goals for their starship vehicle, would it be the king of other applications. Maybe. Maybe, not and all the that decision, for the rocket scientists, and engineers who, get to make all those crazy decisions, every single day so what do you think is it, worth all this hassle to develop such a crazy and complex engine is this. Just the beginning for the Raptor engine and most, importantly is the, Raptor engine really the king of rocket, engines let. Me know your thoughts in the comments below okay I know I say this every video but I honestly could, not have done this video without helping, my patreon, supporters they. Not only kept me sane for the past five months as I worked on this video but they also went over all the data with me they got gave me great feedback in suggestions in the edits of this video if. You want to help support what I do or provide, feedback in videos or help script in research or if you just want to hang out and talk space consider, joining our exclusive, discord channel and our exclusive subreddit, by becoming a patreon member by going to, slash, everyday, astronaut thank. You guys seriously I couldn't have made this video without you and while you're online be sure and check out my web store seriously, I have really cool things like these f1, t-shirts, tons, of other shirts there's, lots of new merchandise popping, up in there all the time so check back often we have things like grid fitting out of coasters and hats and shirts and mugs and prints just, literally, tons of cool rocket stuff so if that's your type of thing be, sure and check out my web store every day astronaut comm slash shop and then click on the music tab if you want to check out any of the songs used in this video that's all music that I've written over the years you.

Can Listen to it on Apple, iTunes and, Spotify and, Google music all that stuff and also, there's a playlist right here on YouTube for music video versions of that too as well which is a fun way to watch, and listen so, show it to a friend. Thanks everybody that's gonna do it for me I'm Tim Dodd the everyday astronaut, bringing space down to earth for everyday people. You.

2019-05-26 18:23

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Elon watched the video and provided some additional input in this tweet - "Great video. Couple notes: Raptor designed for subcooled CH4/O2, so propellant density & thrust increase up to ~8%, as needed for mission. 380 Isp & up to 50% thrust/weight improvement over time. Merlin thrust/weight doubled from V1, but Raptor is closer to optimum." and this one - "Propellant stays same, but almost everything else improves. Fundamental goal is minimize cost per ton to surface of Mars."

I had never noticed (totally not space related) that you have heterochromia

Love the fact that SpaceX looking long term in selecting fuel option due to availability on Mars. I hope I see them get there in my life time, would be dream come true for alot of us mere mortals that see colonizing Mars is essential to survival of humanity.

+Gibacke Seriously? Please check this again, you are wrong! The problem (Houston, we have a problem!) begin at about halfway to the moon, the F1 engines of Saturn V was on the ocean floor long ago.

+alxo82 NO! 10m is 1 bar!

​+alxo82 had the same thought during the video.

+Denis Mehmedoff excellent idea

+Gibacke S II not F 1

+alxo82 learning is my favorite thing! Teaching second. Love love that comment thanks!


Whaaat? So the Merlin’s trust to weight ratio is around 400:1 ?!?!

This was really very very good video Tim u just nailed it

+Jacob Rubio yeah, I was wrong!

+gasdive you're right, all my life I thought it was 1 m = 1 atm, you never stop learning!

+alxo82 round numbers, there's 1bar / Atmosphere every 10 meters, so 300 bar times 10 is equal to 3000 meters which is equal to 3Km depth on salt water, so Tim is right

+Kingsley Knoxlar I know, I really enjoyed it, Charlie Stross does a good job of presenting it ;)

The Best video so far, I guess you could apply for professor job at California Institute of Technology.

Cool story bro.

In answer to the question you posed, re: King of Rocket Engines, it may be, but the Queen of Escalation of Rocket engines has to be the electric fed 24mHg/FOOF with graser amp

Awesome video!

@everydayastronaut you should team up with Jared Owen he makes awesome animations and you could explain

+Dan short sellers, and competitors, or there fan base. Really you know your doing a good job when they get pissed off. Means they are nervous.

I just noticed, do you have heterochromia?

Who the heck down votes on videos like this...?

Thanks for the great presentation. I learned so much watching your videos. Your enthusiasm is contagious!!!

How exciting to get a comment and commendation from the man himself. Great job.

Does 'cost per flight' include refurb cost?

+alxo82 No. 10m of sea water is about one atm of pressure. I'm a commercial diver and recompression chamber operator. I know what I'm talking about on this one. Tim has the right numbers, you don't.

Amazing video Tim, really bringing rocket science down to earth for the rest of us!

Well, you did ask Elon to do an Interview to tighten up the data, or free it, or something:)

You forgot they can be carbon neutral on earth

+Gibacke The F1 never has failed. Your probably thinking about the J-2 second stage engine failure.

+OMSI-Fan Mark I was wondering to. But he can't take a job at spaceX because then he would not be allowed to leak the info :p

Elon virtually knighted Tim for producing this video. I wonder when Tim will be starting to host or co-host live broadcasts or producing official video material for SpaceX.

Ugh @ Mark B Spiegel inserting himself everywhere

Wow thats really cool! You make really high quality content, so it's not that surprising that even Elon watches it . Also love that they had your sticker on the computer on the livestream once.

awesome video Tim i know have a much better understanding of different engines :)

+Harald Ferron J Pentad 1 m under sea = 1 atm = 1.01 bar

+alxo82 Every 10m of depth adds 1 bar . And 300psi = 20.67 bar.. But he meant 300bar times 10 equals 3000m

Hi Tim, 300 bar is not the equivalent to 3 km deep under the sea but 300 meters. EDIT: I was wrong and it is 3 km, Tim is right

@Everyday Astronaut... you should submit one of your documentaries to the Academy Awards.

Tim, the link to the first Elon tweet takes you to this video. It needs changing to Elon's tweet.

Totally worth the time. You should have made this video earlier. Please make a video of airospike. Is it possible to combine airospike with raptor design?

engine F-1 fail mission Apollo 13

Senpai notice you. Interview soon.

Thanks for the update and I have to thank you once again for your superb explanation!

on flight record, for Merlin, RS-25 and F-1, multiple have flown per flight, for M1d multiply by 10, RS-25 x 3, and F-1 x 5 also M1D hasn't failed in flight, only M1C

Very awesome that Elon watched and then commented on your video.

Wow. Elon probably subscribed to you. Great work!

Amazing video! Took time but totally worth it. For future reference, this is the go to video for any rocket-engine related things

Congratulations.. and Thank you for all your hard works and commitments

Do you think he watched the whole thing through? Probably on x2. Job offer from SpaceX not far behind.

If Elon is interested, you clearly did something right!

That's awesome! Does this mean the TWR increases to about 150?

Everyday Astronaut good work man!

No expander cycle engine and no electric motor engine?!

Amazing job! I know how much work it is to make a video, and I can tell this has was a LOT of effort. But it is the kind of stuff people really want to learn. This is one of those videos where you don't really notice the length. I actually know a lot of the content already, but it was fun to see how you chose to present it, and I learned a number of new details myself. I've tried to write about this myself in the past. E.g. how to chose rocket engine and propellant: You did a really good job explaining specific impulse (ISP) I think. I've also tried writing about it, but getting a bit more into the math, delta-v etc: If I was to nitpick, I think it would have been good to mention WHEN ISP matters and WHEN thrust to weight ration (TWR) matters. For the booster stage when you are going vertical, TWR matters a lot more than ISP, because you are fighting gravity every second and has to spend as short time fighting gravity as possible. As soon as you start going horizontally though and you don't fight gravity, ISP starts to be a far more important metric. Which is why upper stages tend to have low thrust and high ISP engines, while the bottom stages tend to have really powerful but less efficient engines. Raptor seems like an awesome engine as it works good both as a first stage and upper stage engine. I am really excited to see what this engine will accomplish.

Awesome video! Really helps me to get a feel for how hard “Rocket Science” actually is!

Excellent video. Clearest description of Isp I've heard.

Excellent video, thanks man

Excellent video. Some new information for me and in metric units for the most part. Loved the explanation of Isp.

Great thx for this very useful video!

Very well scripted video! Was really interesting to watch!

50 min of pure entertainment! Thank you again Tim!

Very interesting video. Thanks.

The F-1 had 17 flights? There were only 13 Saturn V launches. Was it used in any vehicle other than Saturn V?

Could you produce methane using the sabatier process on earth to neutralise the carbon emissions from burining methane?

Amazing work, so much information packed into this! Keep up the fantastic work!!

Hi Tim, really great detailed work. Very interesting and much appreciated. Since the choice of fuel type affects tank size and mass, you could add tanks and engine masses together for each design of rocket first stage (taking into account the number of engines etc) to derive the thrust to weight ratio of a booster. Could you present a comparison of the thrust to weight ratios of first stage boosters, or would that not be a helpful or possible comparison for some reason?

hmm, maybe i got it wrong but the part with oxidiser and fuel radio / tank volume something is wrong... i need to rewatch that

49 minutes of Everyday Astronaut? **Grabs Popcorn*

Absolutely brilliant video.

I tried to like this twice

I probably learned more about thruster engines today than I have my entire life.

You didnt mention methane is potentially 100% renewable (ie produced by biodigester) so methane just makes commercial sense over purely fossil fuels in an uncertain regulatory environment looking over the decades of planned usage

I enjoyed the hell out of this video! Great work!

Well worth the wait Tim, great video. I think you nailed the mission brief.

Thank you for this excellent video

> Is it the king of rocket engines? > This is the holy grail of rocket engines! > So, let's see whether Raptor is the kind of rocket engines! Uhh... dunno about that, but it sure looks like a goblet.

Буран энергия

Cooling jacket (I don't know what is the english term, in russian it is often called "рубашка охлаждения") is missing in visualization, but since we're talking about cycles, it isn't much of an error. It was very useful for repetition for my propulsion systems exam!

Hey there. Small suggestion: get yourself some makeup. You're glowing like the sun in this video. Also maybe don't put light grey on white. I'm getting snowblind at 21:10

phenomenal thats it, 49:01 of phenomenal

This has got to be one of my favourite videos you have ever produced. Thanks for all of your hard work on this Tim and those that contributed. The everyday astronaut rules.

Why are you using a sun glas frame for clear glasses?

Very informative video; great work all round. I'd love to see a video on engine nozzle designs based on different atmospheric pressures and if we will see an adaptive nozzle design that can change its profile to suit all stages of the mission. Impossible.... yes, but SpaceX are doing the impossible every day :)

Great content, so good. Subbed

Fantastic job! Everything very simple and easy to understand.

Sure, hydrogen will be made on Mars. When? 2500?

Have been meaning to, but that was absolutely worth a Patreon subscription, tis done!

Very good video

Thank you Tim. Excellent video. Just the right length and fact density per minute. Had to rewind a few times but that's the beauty of YouTube so no need to slow it down. Congrats on Elon's kudos too. Well deserved. Mammoth effort mate.

THIS Tim, is your best work to date. Brilliant. Keep it up.

Thank you. Now I understand at least few things about rocket engines.

this video is truely an amazing achievement and takes the most complex part of the engineering of total space flight systems design down to earth. thank you.

Hey Tim, what a fantastic video. You should really consider a career as a professor for aerospace students. :D One little note on the F1 reliability: didn't one of the first stage engines on Apollo 13 shut off early? Or does this count as successful because the engine was supposed to shut off because of pogo? Thank you for your fantastic work!

I don't know why people disliked this video. You make space technology and rocket science easily available for us. Premium content, keep it up. Also, I would have totally loved to see ISRO's VIKAS engine up there in the comparison. Love from India. ❤️

fantastic video. but ibthink the flight record should take into account the number of engines on each flight... since we are talking about flight reliability of an engine. like 3 on a shuttle flight, 9 on a falcon9 flight..?

I thought Apollo’s 13 center F1 engine shutdown during launch

I usually don't mind the ads, but these ads were interrupting the super pleasant topic transition music! Boo! Other than that, well done! I'm certain the research was both time consuming and frustrating, but the simplified end result was very easy to digest. I thoroughly enjoyed ever second of this video!

But the RS-25 requires Hydrogen and insulation around its tanks and we all know what danger that brings.

This has been the best explanation of all the engine types ever. Really clear and detailed explanation. I was about to check out the cost difference between Methane and RP-1 and you even covered that although from what I've found on internet the cost difference for RP-1 is two orders of magnitude more than methane. Given the icky rubbish which come burning fossils, Methane is a really great choice.

Amazing video!! Gonna have to put this new job coming up to good use so I can join your patreon.

that was super well explained thanks!

Awesome work, great presentation of complex subject matter !

Very good visualizations & really great explained! The best Video i watched so far about this subject :) Greetings from a German Tim

I literally realised that this video's 50mins long, 25mins in

It's not like this is rocket science or anything...

Very nice video. You really made everything easy to understand and interesting thanks!

Great Video!

First ever rocket video I have seen, great job on a complex subject. Thanks!

Thank you for an excellent video!

What an amazing video. Thanks for the great content.

Awesome job, Tim! I've already knew everything you've told about, but it's still very-very interesting and fun to watch. I'm sure, these engine cycles animations will be used all over the world for many years. Thank you!

Буран Энергия Buran Energia Great nod to marvelous engineering.

I thought that the F1 of the Saturn V is the least efficient, most expensive engine. But you really see how expensive the space shuttle was.

Probably for a Rocket Science interested like me ...its pretty much accomplishable for urself to know more than others...initial stage it was a pretty much complex . . . But then started getting better . keep going bro...done a great job

Hi Tim, I don't usually comment on videos, but I had to tell you that the quality of this video is astonishing! Great work, super interesting!

The best vid from you so far. Great loved it.

Uhh I think the US govt needs to watch the section covering cost/kN..... Really I mean even if there are moderate variations in the costs from figures shown the difference is still staggering between Space X and the rest I mean come on!!!!!!


Elon should give Everyday Astronaut aa job in media for Space X. He's not just a pro but makes everything fun and interesting and has seriously infectious enthusiasm too.

Thank you very much for the video, but you have one inaccuracy. RD-180 engine though was not reused, but it can be reused up to 10 times. As well as all descendants the RD-170 engine.

yes, i can just follow the other comments: great video! thanks!

Amazing video thank you very much for it! The tease for how to start-up a turbo pump was a bit painful since that puzzles me greatly. Looking forward to that video!

Absolutely excellent explanation and overview of the top level design considerations going into rocket engine choices. (with acknowledgement from "The Master" himself! Certainly The King of Rocket Engine explanation Videos!

Well done! That was badass. With my background in home recording, I can see that this was SO much work, and you nailed it! BTW - I watch all of your launch live streams. :)

Thanks a lot for that very nice video

Finally a very good video that explains the rocket engines

You're a true pro. Fantastic production values, amazingly detailed research but best of all clear and concise delivery but still fun! Thank you

Cannot believe 94 people downvoted this. Well, I suppose it takes all types.


Well done....Need more like this

Those floating planets are dope where are they from?

i liked and subscribed, should have a while ago. Staged combustion methane powered rocket of love to you.

42:12 I'd agrue the F-1 has flown 85 times, because it was 5 engines per launch. Same with the merlin

Amazing video!

Really great video. Not sure about the title though because you discuss an array of engines. Thanks for the effort!

Thanks Tim excellent vid, I will need to watch a couple times but really appreciate the effort to inform space fans like myself with simple explanations. Lot to absorb but definitely right up there as one of my favorites.

This is great! Thanks Tim for all your hard work and time you invested!

I'm so so grateful for this video!!

Raptor is a King engine for long trips.

The most impressive thing about the Raptor engine is it looks like its going to get its first test flight a year earlier than was slated when the basic design concept was finalised . At the heart of SpaceX's success is the use of advanced modelling, manufacturing, and testing methods to iterate designs rapidly and economically. A small engineering team can achieve in days or weeks what much larger teams could formally only achieve in months or years.

well clearly russians are well ahead in trems of rocket engines

Noting flows like a big fart!

Brilliant video, piles of info. I know a lot more now than I ever have. It's true that rocket science really is complex.

A masterpiece. Great job, Tim!

Is F-1 really at 100%? What about Apollo 6?

+Welyum indeed, you are right... Well, F1 was based on a German design

That has been the j-2

Literally a million times better than your post on SSTO... You've left the genre of enthusiast videos and your producing real educational resources... Don't be surprised if your video gets referenced on engineering courses in future.... Excellent job

Do we know where the name ‘raptor’ comes from?

I'm impressed. This was super interesting, I have also been trying to research what was great about the Raptor engine, but didn't appreciate it until now. I will be coming back to this video later to refresh on the subject since it's a lot to take in. Good job on making this stuff so entertaining to watch

Remember that the RS-25 will be thrown away with each SLS launch, although being reusable. That means they throw away engines for $200mio each flight! And that's only the engines. SLS is dead.

good work wil wheaton.

TOP VIDEO TIM. that was awesome, I loved the simply complex graphics of the rocket engines, it helped my simple little mind grasp the immense job these engineers are doing to help us become a interplanetary species. THANK YOU . THANK YOU. JUST... THANK YOU

A really good video and great topic to use to introduce the different models of rocket engines. No suprise Elon watched it, you want to know what people are posting about your company are true. So far this is the best video I have come across to set out the foundations of current rocket engines. One point you went from pressure rockets to flow cycles with out the step of burning fuel. I know it's "obvious" but you have the water rocket or fire extinguisher thruster. Then you have rocker that burn but are pressurised with compressed gas but burn the fuel. However great video worth the 50 miniutes of my time to watch. :)

RD-170 has barely flown? you might want to google "Zenit". other wise another stellar vid full of great info and ever increasing production values

I already understand the electron rocket and why it's such a big deal! Why isn't Elon doing this for their raptor engine?

+Dan Jeff who?

+Dan Jeff

+Gibacke Wrong. That was an oxygen tank explosion on the command module, which was the 3rd stage of the rocket. F-1 engines powered the 1st stage and fell back to the ocean once the fuel in the stage was depleted.

Personal replies from Elon Musk and Scott Manley. Baller.

that's a link to this video, not his tweet :D

Hey Tim, great video. Definitely will rewatch multiple times, but why don't they just...... Turn the landing pad of the drone ships into a gimbal system to balance the return booster? To balance out the tides. If you do read this, Thank you!

Where did you get models of falcon rockets? Which scale? Where i can get also?

+Carl Davies it seems that SpaceX would not have advantage of using untested designs like the airospike untill they are interested to build SSTO. It seems that vacuum optimised nozzles are more efficient than a airospike design at least in vacuum so SpaceX is actually well served by the current multi stage design for moon and mars missions.

+OMSI-Fan Mark dude that's a great idea they just need to let Tim host the official launch channel!

+Oli R someone will eventually have to take over from John Insprucker, and, I think Tim would do MUCH better job then those young boys and gals commenting falcon 9 launches now, it's often almost uncomfortable watching them being eaten by nerves on live stream, good for them and well done Elon for giving them a chance and throwing them into a deep water but for pure viewing pleasure someone with a lot of passion, a lot of knowledge and insight (these guys probably have all of those qualities to be fair), but ALSO is not scared of a camera pointed at them streaming live show to millions of people around the world would-now this would be a treat. Tim's live streams have more hits then Space X's-hint hint Elon.

+Iván Cañada would also recommend Scott Manly's video on rocket engines, deliberately won't put the link in, leave you with the pleasure of digging it out of the rest of amazing content this guy produces.

Great job ) now I know more about rockets))

+Gibacke on Apollo 13, all F1 engines worked (first stage), but the center engine of the second stage failed and cut out early. Those were different engines.

+Hat Man he does

Well, Tim, it's such an honor to have your video reviewed and commented upon by Elon Musk himself. It's wonderful to have someone like you around to translate all this for us -- mere mortals. I watched to the end and will watch again! You're a treasure. Looking forward to more Rocket Science from you!

Wha? You act like Elon is some sort of ENGINEER or something ;) ...

Gibacke: I believe that failure occurred in the 2nd stage which would have been a J-2 engine. F-1 engines were only on the first stage.

Why did the RD-275 project stop? It was going to be the second most powerful engine in the world


Awesome video! Will you also do video’s about Vector Launch vs Rocketlab vs Virgin Orbit?, or Firefly Aerospace vs Relativity Space? It’s interesting what those small launchers are going to do in the comming two years and who of them will survive. And will they push The Pegasus rocket out of competition?

*cries in RD-170*

Great Video, yet again! You are brilliant, and you show that you have the interests and willpower, to try make advanced stuff more simple, of people to understand. Many people love space, but only half, does understand how to travel in space, and orbital velocity and maneuvering. Tim Dodd. I hope you are rewarded well, from your content, that will motivated you to continue. You are a true star, and a Very important person, for space industry. Thanks for your contribution, to the leymens knowledge expansion :D :D PS! Elon Musk, is so much fun, and a its truly amazing, he cares about what internet say about his companies, that he will send you messages, to explain some details, or give more information around it. Id take it as a compliment. That the owner want you to have more information about his products. again. Great work, and congratulations! :D I think, this is one of my best chanal ive sub-ed to

Great work Tim really interesting stuf, well explained and reasonably easy to understand for something so complex (my 14 yr old followed it for the most part so that's saying something) really enjoyed it I hope you do more like this

so good, much learn.

Rockets are like horses, cars, and ships...there are lots of variations to fulfill a variety of different needs.

Wow Tim! Thank you! A rocket scientist would have had trouble explaining it and you just nailed it! Kudos to you!

Excellent video. I know you have agonized over this video for some time, but the results are what you hoped for. Good balance between useful info, and nor getting bogged down with to many detail. My hope is that many other channels will link to this for various reasons. Consider your self as having done the human race a favor.

This Video is amazing.

4:00 wow that's an awesome machine!

Hi @everyday Astronaut, this video is now listed on a Dutch news website. You are becoming famous.

Awesome video!! I didn't mind the length at all and will probably end up watching it again! :)

I could have sworn there was an F1 shutdown.

Amazing work! One note: it's definitely incorrect to say that Merlin had 71 flights while they have 10 engines per flight. Same with F-1 and RS-25.

Excellent video. Very educational and informative! Good job.

Everyday astronaut bonus drinking game! Take a shot every time Tim says “crazy”. And may the gods have mercy on your liver...

RD-170 barely flew??? There were 4 of the on each of the two Energia launches and one on each of the 84 Zenit launches. Technically the latter were RD-171s, but they produced the same amount of thrust.

I bailed at the 5th "hopefully" bogan adverbial phrase.

Omg the fathom joke made me spit out my Frosted Flakes

Awesome Tim, it was definitely worth the wait!

Nice job. Bringing Rocket Science down to Earth for everyday people.

I’d be a little more specific on which engine types. There’s 3-4 different varieties of Merlins, RS-25, F1. The f-1B is one that I would have like to seen added in. While it is theoretical it shows what a large open cycle could do. It also shows while old isn’t always better old can be cheaper with new manufacturing techniques. You did short the f-1 some most later F-1 were making closer to 6.96MN. I’m going to call BS on the 99.5 for the RS-25 reliability, it never failed in flight or led to a flight failure.

Sufficiently content dense to keep me around to watch the whole thing and easily palatable, probably best description of each topic I've seen, all compiled into one great video. Big ups my dude. Now off to patreon.

Americans and their engine names....

PLEASE do a video on engine startups! I can't find any on YouTube!

Nice job sir! Love the detail.

I watched the whole video!

You sir, are a steely eyed missile man... couldn't stop watching. Thank you.

I don't think there is a king of rocket engines. They are all purpose built. They are all the king of doing what they were made to do until a new one is made to do that same thing.

Dude! Your channel is the most interesting thing on the internet! Keep up the awesome work! Thanks for the breakdown! I feel like a rocket scientist now! HA!

Not yet, but it will be.

This is a great video. Well done and quite interesting.

Great job, Tim. You have made these complex concepts easy to understand.

At this point in time: 313k subscribed. 253,114 views. 18,789 up votes. 175 down votes. That last number I don't understand.

For reliability shouldnt we count 70x10=700 for Marlin, 135x3=405 for RS-25 and 17x5=85 for F-1?

amazing content! Thank you comrade

Thank for your research very interesting. enjoyed it very much

But musk chop speaks his share of bullshit

I don't know who you are but this and the accompanying article are fantastic.

I could have watched another hour of that.

Лайк за футболку Энергия-Буран!!! Like for Energia-Buran t-short :)

Good info. Thanks.

Watching this episode stoned was a bad choice...

Why are all of the BE-4 specs negative? Did you add an extra minus sign on accident?

+Steve Scharmer gotcha. I'm in a rural area and am limited to a low resolution, so it looks like a minus sign on my screen.

That is a symbol for approximate (since things are unknown), not "negative".

Excellent editing! video and data visuals were expertly timed and inserted. More charts please (I'm a visual learner)

This was a great video. Also, can you please make video just on the different types of liquid fuel engines and how they work and go into more detail.

Omg Tim! We love your content and constant high production values, but WOW!!! This is your best video EVER! Worth the wait!

Brilliant as always. Love the presentation, research and knowledge you bring to this subject. As usual, most rocketed way above my head. But hugely impressed you knocked this doco out in just a coupla days . .

For the record, Tim, Russia is bringing back a new version of the RD-170 that powered Energia. The new RD-171MV will power the Soyuz-5 Irtysh, built by RSC Progress in Samara, the same company that builds the Soyuz 2.1a which lofts the Soyuz manned spacecraft and Progress cargo containers to the ISS. According to a May 24, 2019 speech at Moscow State University by Roscosmos head Dmitriy Rogozin, Soyuz-5 Irtysh will come in a single stick version powered by a single RD-171MV. This will be the vehicle that will launch Russia's new Federation spacecraft to LEO. A superheavy version nicknamed Superthrust will have six strap-on Soyuz-5 cores around a central core booster with a total of six RD-171MV engines with a total of 24 combustion chambers. This vehicle will be the core of Russia's Lunar program, again according to Rogozin's speech at MSU.

I'm sure Tim is open to adding more to his web site article for engine comparisons. (He said that will be the place to look for updates as development of engines continues.)

"The people that think of this stuff are nuts".

Spoiler.... it isn't

It's too hard to estimate, but there are "refurbishment" costs. The space shuttle RS-25 engines were fairly infamous for how expensive they were to refurbish for the next flight. Early versions were notorious for developing cracks in the turbines. Maybe worth mentioning refurbishment-costs in passing, although public figures are prob really hard to track down.

Awesome video

Did that whole vid in one take.

RD-180 is king


Excellent explanation!

Great video! Really well summarized.

This video is awesome...nice work!

Wait until the Sabre engine comes online :)

Love videos like this, I hate when I see your videos and go "oh no, I already learned it all" because they are such high quality.

Have you considered doing a breakdown of the rocket Motor into it's functional elements, such as the mixing/detonation chamber, from which it then passes to its expansion chamber, where the trust is obtained, and then consider the product of the combustion at the end of that cycle, such as highly excited molecules or elements, which could be separated into their positive and negative components and further accelerated against magnetic fields, all while increasing the output's velocity, and reaction?

Well.... that cleared quite a few things up for me. Thanks man! Really enjoyed it... guess I'll watch it again.

Great video. Not many channels I would watch such a long video on, but this one I enjoyed very much.

Thank you, Tim.

Very good educational video - thank you

Esse vídeo é uma aula, um incrível e objetivo documentário muito bem feito, você deveria ir para a TV meu caro. Obrigado pelo excelente trabalho e por favor não ligue para os chatos falando que o vídeo "foi muito longo", é um assunto complexo e não dá para ser tão curto.

One of the best rocket/space related video I have seen in a long time. Keep up the good work Tim!

good job you put a lot of info on and made it come out very out clear. my brain will take a while to absorb .

Excellent work Tim. A well rounded critique of the current engines, and the best explanation of specific impulse I've encountered.

Can they use electric pumps?

Yes. A New Zealand / USA company *Rocket Lab* is putting payloads into orbit on their _Electron_ rocket. Its engines use electric pumps powered by batteries.

Not unless you have a really really reeeally long extension cord. :) The problem with electric is powering them. Those pumps are in the hundred thousand HP range, that's a lot of power and that means a lot of electricity. At the moment there is nothing that can store enough or generate enough and sill be low enough in mass to be practical.

You failed to mention one of spacex's biggest breakthroughs. Pintle injection. It allows the engines to be much smaller and simpler than plate injection. No one else was able to make it work in large high power engines the way SpaceX has.

Pintle vs Plate injection? Please summarise what these are.

Outstanding presentation.

Very nice T-shirt you have!

Just a small note on how you mentioned that the RD-170 was almost never flown. The RD-171, which is based on the RD-170 but with nozzles that swivelled on both axis, was flown quite frequently on the Zenit rocket family operated by the USSR and later by Ukraine and Russia.

Love the video. Brings out so much affinity for all the engineering.

Ahead of the curve my friend. I tip my hat to you.

Also this must have taken AT LEAST 1 month to edit. Tons of graphics...

BRO the Swivel and Reliant engines in KSP are open cycle because they have the exhaust!!!

It's rare to see videos of this quality. Well done, sir!

Raptor engine should be listed on the dollar menu with its $1/N ratio.

Another huge advantage of Full-Flow Staged Combustion is that all of the fuel and all of the oxidizer have been heated up by the preburners this allows for the fuel and oxidizer to enter the combustion chamber in gaseous forms which will result in much much better fuel/oxidizer mixing. This could also reduce the costs of the injector plate on the combustion chamber which would usually need hundreds of precisely machined holes to ensure that the liquid fuel and oxidizer are divided into small droplets and are mixed, but with gaseous propellents entering the combustion chamber, there is no need for such complicated systems.

Very well done Tim! Intro to rocket engine design in 49 minutes, clear concise man on the street exposition of complex concepts. Who needs Neil DeGrasse anyway? Making hard things seem (relatively) easy is the hardest thing of all.

Awesome video, I fell much smarter now, almost like it could build one myself...

His eyes are different colors

Love the Energia Buran t-shirt.

Wow! Great explainer video that fills some useful gaps and synthesizes a lot of information to make sense of otherwise inscrutable design choices. Thanks for your hard work; I'm sure this will be a well-used resource.

Where do solid fuels enter this game? And how do you make methane on Mars? Is there carbon and hydrogen there?

Solids just burn. No pumps.. Methane is made on mars using the Sabatier process. The hydrogen comes from water, and the carbon from the Co2.

Good work, this video was worth waiting for for sure. Will be watching this many times :)

RS-25 "Unmatched efficiency" RL 10: Am I a joke to you?

Surely the difference of isp between RS-25 and the other engines is largely due to using different fuels? I.e. this comparison doesn't enable us to judge other engine design aspects easily.

Brilliant video, easily understood. Love your work, Thank you yet again

Great effort! Rocket science is deceptively hard! FAB!

Best. content. on. YouTube.

Ok, I'll also use raptor engines.

Legitimately probably was more in depth than my advanced propulsion class at penn state as an aerospace engineer. Great information and break down Tim, you know how to provide the information in a way most people can understand. Hats off to that not many people can do that.

Best Video Yet! You should have a Netflix documentary series

Wow, thank you. A worthy deep (ish) dive but just what normal folk needs to grasp rocket science!

+Lucifer No it didn't it was the center engine of the Second stage J2 engine that failed on Apollo 25.

+Agshin Yusifzada

Failed space hardware 3?

+Jason Lee That's cause Elon is an engineer though he is an electrical engineer by training, though he does have a good grasp of many engineering fields.

+Gibacke No cause technically it was a tank failure in the upper stage, so not an F1 failure and not even on the same stage as F1.

Fantastic info! Keep up the amazing content. You sir are providing much joy to this 49year old dude that loved space as a child and went through horrible disappoint when we didn't continue to the moon and beyond. I had given up on ever seeing progress in space travel. With Elon Musk embracing interplanetary travel it has reignited the passion and your channel is a fantastic source I use to keep up with current events. You rock! Thanks again!

+Oli R Certainly for their public outreach branch. What a great communicator!!

+Oli R Yeah, they will want Everyday Astronaut as their PR guy. As much as all other space agencies / companies do. :)

Gibacke I think this just counts launches. Otherwise how should you count reignitions mid-flight for some mission profiles but not others?

Consider breaking up videos like these into smaller chunks: It'll feel like less of a slog for your viewers. You can get more adds in. And it'll improve your integration with the YouTube algorithm.

Great channel dude! Elon should support you cuz u simplify these ideas to ordinary ppl like me

+Gibacke no Oxygen tank ruptured, the engine didn't fail

+Kārlis Zauersfailed second stage ,1 engine

Tim, if Elon succeeds in achieving $00k round trip tickets to Mars, will you go? The idea is to sell all your earthly possessions to raise the cash. Most working adults without children in the Western world could scrounge up $200k buy selling their stuff.

Hey .. Your camera working yet ? XD

+Gibacke the engine didn't fail on that flight

F1: the center engine of Apollo 13 failed and almost blew the rocket.

Hi Tim You had to glance at RD-171 for Zenit Rocket nevertheless.

Amazing video. I feel that I will be watching this a few times to fully absorb it all.

This is an excellent video! Thanks so much for your hard work putting it together

Thank you, will have to watch this video a few times to get all the technology to sink in to my head :-)

I love these 50 minute videos. It feels like a proper documentary. Please make more like this.

Cool job

Fantastic video! Thanks!

What a superb video, thank you. Is there anyway I can send small financial reward without joining facebook etc?

You really know your stuff

rocketdyne F1 master race

Superb. Thank you.

Around 42:10 you seem to compare the number of rockets flown with the listed engine. But since you're comparing engines, not rockets, let's compare the number of engines flown instead. So the number of rockets flown multiplied by the number of engines per flight. That gives us the following number of engines flown: Merlin: 710 RD-180: 79 F-1: 85 RS-25: 405 Otherwise good video, even if it gets a little dry when you're just listing numbers in the second half. A little more comparison would have been nice here.

Do you think it's going to work I hear the drums

I didn't think it was already over. Easy to watch young man. Love your work.

No its not.

Thx for using SI-units! :)

Wery nice research, thank You for such big ammount of information at once.

What a beauty

Why isn't everyone using methane, then?

nice one on the hindenburg, off point and showing an evident bias. even though CH4 is a more dangerous flammable and we deal with it in our homes due to its higher density and lower diffusivity. the reality is methane is the better option for mars settlements, but purely as a rocket fuel it has a slightly higher isp over rp1 with the added cost of cryogenic handling and storage, while coming nowere near the performance of liquid hydrogen. other optimisations such as sub cooling, common bulkhead, self pressurisation etc still don't make it nearly as efficient as LH2. so I don't understand why everyone is so biased.

So, not the _best_ at anything (except maybe cost), but good enough in enough fields to be a jack-of-all-stats design.

nice shirt крутая майка где купить можно?

Why is this video so much better than your other videos? I dont know, but if you can work it out and make your new videos this good, you will get a lot more subs. Keep up the good work!

Amazing video Tim!!!! Look forward to the follow ups

The friend who recommended this video: You'll understand it, it's not rocket science!

Thanks for the awesome video. You're making me a smarter and more informed human. For free! (hmmm I should really remember to turn off my adblocker for YouTube.)

You deserve a lot

Can this engine scale up (in size) vs just scaling out (number of engines). the Russian moon rocket had many reliable engines, but it only takes one bad one to go catastrophic and the whole thing goes boom. Great video!

I’ll watch the adds to get you some cash.

It seems to me that what is needed is as you say a goldie locks solution to the complex decision of which rocket engine is the most suitable for immediate development. Keying on one or a combination of a few characteristics and shooting to pick the absolute best of everything is a good way to get exactly zilch done. Its sort of like a friend of mine an Air Force Academy graduate told me that the air force's objective in cadet recruitment was and is to seek out competitive individuals who are well rounded good at various tasks over the full spectrum but not necessarily highly developed in one or two specific areas. Geniuses tend to be very very good head and shoulders above everyone else in a relatively narrow spectrum. They also tend to utterly suck at anything that is outside their immediate sphere of ability. That's not always the case but in general, it's a pretty fair rule of thumb. The issue is can the individual work at a high degree of productivity in a variety of settings. The same thing seems to be at issue with the Raptor Engine. We need an engine that is very good over the entire spectrum of specifications but not one that is truly outstanding in only one or a few of those pertinent specifications. In other words not too hot and not too cold . . . just right will do just fine. I truly enjoyed your YouTube production and believe it is worthwhile for any STEM program. I am a retired air force officer and science and mathematics teacher, my students would have benefited I think from your presentation.

It’s like a movie, well at least a quality doco. Not joking either, top tier stuff.

"...hard to fathom..." got a quite loud groan from me, even before the on-screen explainer.

Didn’t the RD180 have a safe chamber pressure 265 but it could go higher

I took notes by watching this video 3 times (which I never did before even during my universities days)

Great work! Worth the wait:)

So I've never watched one of this guy's videos before. Is it my monitor or does he have two different color eyes? Also, really interesting video! I'v done a bit of amateur rocketry. Only LVL1 stuff but this is cool.

"it's not rocket science" takes on real meaning with this video; great work Tim. Your efforts and application are greatly appreciated.

This guy is excellent.

Best video you've ever done. Thank you and congrats!

Took me more than one sitting to watch the whole thing, but it was worth it. Well done. Earned my sub with this one

Incredible video thanks for the major effort putting it together

This video is amazing.

Loved the video! Thanks Tim!

Great video, you need your own show on Discovery Channel. The subject matter, your presentation, and the production quality of this video is fantastic. You sir are a gifted creator of content, are very intelligent, and I believe you have a bright future ahead of you.

I loved this thanks

This was amazing work. Cant imagine the amount of research you had to do for this. You crushed it. You earned a subscriber. Keep it up!

So just use ammonia. No carbon so no soot, contains more hydrogen per volume than liquid hydrogen, is easy to store, and so on. And then you can run just a fuel rich turbopump so you don't need high temp alloys.

The SLS is a turkey that should have been defunded years ago. Not even the Solid rocket boosters will be reused! The SLS won't reuse any of its components including the RS25 space shuttle main engines. So reusability of the engines on the SLS is a big goose egg, Nadia, Zilh, ZZZero, 00000. It will be by far the most expensive rocket ever flown, or maybe not flown. Pity the SLS should have been relatively rapidly developed and low cost system and have already flown numerous missions for the last 3 years at least. It is made up of already proven space shuttle components. The SRBs could have been recovered as they were with the shuttle and the RS25 main engines could have been recovered using a heat shield and parachute and air bag system for reuse. The SLS survives only because its a pork barrel jobs program. I am not against the SLS but think that it should be made to compete against Space X, Blue Origin, and other space launch companies on the basis of reliability and launch cost, not given government funding to support Boeing and Lockheed Martin.

Wasn't the Hindenburg the paint burning not the hydrogen?? Didn't MythBusters prove this?!

Waaw the amount of effort to make this video is amazing.

If it can do 50 flights, it will be along the simplest engines ever built (per flight)!

Cool video

The point of using Methane is not about the efficiency it is about the availability of the fuel in the solar system. Titan has lakes of Methane it would be silly to disregard this for a starship that is designed to go beyond Mars.

Watched it all, worthed it.

Wonderful video, I hope you make more full length docs like this!

What make segmented shape of the flame

As I imagine you know, hydrogen got a bad rap due to the Hindenburg disaster. However, an aerospace engineer "recently" determined that it was the "rocket fuel-like" dope on the airship's skin that burned like a magician's flashpaper. The hydrogen was secondary.

You use a lot of cred talking about the magic of science

One additional thing, how costly it is to refurbish these engines for additional flights? I wonder if it changes the comparison by much.

Having watched the whole video, I would like to thank you for teaching me so much more about rocket engines and how different engine cycles work. I really appreciate this type of video. Keep it up!

Hmm. A lunar space bridge on the moon for extra thrust at launch to mars?

@Everyday Astronaut - Amazing video, so much information, so clearly and professionally presented and you can feel your energy and enthusiasm about the subject matter. I think I'll have to watch it a few more times to take it all in... and I think I'll probably need to stop the porn playing in the background too! Thank you so much to Tim and all his contributors for doing such a great job :o) And, 50 mins was a perfect length of time for what you presented - Amazing video!

RD-171 (Flew a bunch) Comparison: Closed cycle (Lox rich), RP-1, Thrust 7.2MN (Most powerful), 75:1 thrust-to-weight, 309/337 specific impulse at 245 bar. Essentially a bigger, stronger RD-180, albeit with lower chamber pressure. In the operational section, assuming close proximity to the RD-180, it brings down the $/kN to 3448, which is roughly the same as the BE-4 (Pretty cool for 80's stuff). The re-usability is where it falls flat, along with all it's generation. I wonder what are the challenges associated with producing a reusable version of these old workhorses...

RD-170, which flew on Energia boosters was qualified for 10 flights. (This means several times as many ignitions, to account for testing.) It differs from RD-171 in how it is gimballed. But having a reusable (in principle) engine is only part of making a reusable rocket. The Energia side boosters were supposed to land. Even though the hardware that flew did have compartments for the recovery system components, the recovery have never been worked out. But is was planned even then in the 1980s -- only the fall of USSR did not allow it to happen. The fact that Merlins are less capable engines, and Falcon 9 has to use 9 of them to get sufficient thrust for liftoff, is actually a blessing in disguise, as far as reusability goes. The thrust required for landing propulsively is 20 times less than that required for liftoff. Using one engine out of nine, and even then, throttled down, makes this possible. With larger engines, one would have to do something different. And regardless of what elese one does, one has to use retro-propulsion to re-enter denser atmosphere without destroying the booster. Earliest Falcon 9s tried to do recovery with parachutes only, without retro-thrust. They disintegrated on re-entry. Recovery of Space Shuttle side boosters worked using parachutes only, but the boosters were much sturdier in construction -- half inch steel walls vs 1/8 aluminum alloy walls in Falcon. Lots of people are thinking about making reusable boosters these days, but it is a very hard problem, especially if you have to modify a design already optimized for other parameters (e.g. having only a few of large high performance engines.) Even for SpaceX it took a decade of experimentation to get where they are now.

Seems like Methane is the Goldilocks Fuel. Good compromises all around and easy to produce.

Why don't you give stuff in pound. feet and gallons. This is the USA after all. We use pounds, feet and gallons to put us on the moon! Nobody else has been there.

Upvoted for "I can't even fathom"...seriously though, this is a great explanation for how liquid fueled rockets work. Much of this was old hat for me, but the comparisons side by side of the various ways to accelerate gaseous products in a controlled fashion and hence accelerate the attached apparatus


Methane? Boy, AOC is gonna have a field day with this one. lol

270-300 bar sustained chamber pressure .. is just above the peak chamber pressure of a 9mm pistol firing a round.

it's not rocket surgery

in short- no......NASA retained a consultant 3 years ago (IIRR) to ID the next gen rocket had to be more powerful than anything current (per the spec), efficient, reliable and cost effective......1 year and thousands or staff R&D hours they provided NASA the already have it....the Rocketdyne is the most powerful engine ever built...developing 9 million pounds of peak thrust, burning 95%+ clean/efficient and a reliability factor of 99.8% over 300 launches. In February of this year the next gen engine went through it's 1st full power test in Missisippi….14 million pounds of thrust sustained throughout the test duration, operating at 99.98% efficiency/clean burning.....NASA has formally declared the engine "disposable" since it's design allows a single stage rocket to deliver any size payload to the deepest parts of projected space travel for the next 20+ years...….. Oh, and if you are wondering where the F1 was developed & in West Los Angeles......and who was the lead Engineer.....Dr Werner Von Braun. Space X has a lot to learn

Fantastic video!! :0 :0

Hi Tim, thanks for this great video, I learned a lot!!!

Awesome, Tim, going deep on the subject

Great job! I'm sure this took forever


Hang on, I gotta get a snack...OK, let's do this.

I didn’t take my eyes off the screen for the entire 49 minutes. To me, this beats any Blockbuster movie, any day of the week. Thank you so much for your time!

"I can't even fathom" at 36:40

I love how you have completely dead eyes. Like there's no soul there. It's amazing!

You can’t kill that which is already dead

I wonder what Elon thinks about all the cool fan sites like you, Cloud licker, and sometimes Scott Manley...? It must be rather gratifying. It's SO cool he offers information edits and updates!!

Great job! Awesome video! Enjoyed it immensely!!

Totally nerding on rocket engine data....

Absolutely awesome video! I really hope you and your content get the recognition you deserve. Subscribed!

Tim, on OLC you expressed some apprehension about this long form video. Turns out you need not have worried. This video is fantastic. I love this *seriously* in depth stuff. THANKS!

I'm definitely gonna have to watch this a couple times to digest it all. Thanks so much for making literal rocket science possible to grasp for us :]

"I can't even fathom" [oh, no you didn't]

Not the usual NASA shirt. Nice

They'd use methane so we can have poo powered rockets when on another planet which means there shooting for a moon on Saturn and the present methane would fuel the trip back

9:52 In my head I was like EGR???? :D

Tim—outstanding discussion of the engines. Thank you. Is there a detailed plan available for the methane generation plant to be constructed on Mars? How many ships will be needed to have all the pieces in place when the people start landing?

That was twice as awesome as I hoped it would be. Thanks Tim!

Are your eyes a different colour, or is it the lighting?

Can you teach my gas dynamics class? lol

So the RS 25 required "a few months of refurbishment" so I don't think you can just divide cost by # of potential flights to get $/kN/flight... I've heard some claims that reburbushing shuttle components (maybe including the engine) cost more than the original manufacture costs.

Do you have 2 different color eyes?

Wow, your explanation was really good and interesting!

It's all fiction

Great vid, Tim. It was worth the waiting :) Pro quality ! Elon's not mistaken ;) I'm definitely not a connoisseur, but I've got my lego's Saturn V to begin with and I really enjoyed it ! #born1969 #olf #EverydayAstronaut

Thank you for producing a well documented and well understood video on rocket engines. This should be shown in classrooms to engage the next Generation of where we have been and what is to become to get us efficiently into Space. Well done!

It's still just a Newtonian device - trying to perfect the steam engine (methane + O2 = H2O + CO2) isn't going to get humans very far.

+Lucifer 2nd stage center engine failed not an f1 on the first stage.

The RD170/171 has been launched into space som 70-80 times. It is the most powerful liquid fueld rocket engine ever made, and it should be in the comparison. The RD-180 is also designed to be reused 10 times.

With this in mind, can you do a video on the "open expander" cycle Aeon rocket by Relativity Space? The 3d Printed one.

Tim, you're a magician. Truly. Hardly anyone else could make a nearly 50 minutes video explaining details of rocket science, that ends rapidly and one asks "really? I thought it was 50 minutes... oh." :)

I never thought I'd know so much about rocket engines... Not only was this relatively simple to understand (considering the complex topic) but also extremely interesting to watch. just an amazing work, thank you!

More like a curiosity stream documentary!

because - methane doesn't explode in direct contact with air unlike hydrogen and its the second best fuel (mass/boost).

Great video. I've been into rocketry for maybe a couple of years now and I felt this video had the right level of complex content to keep me interested and explained in a very clear and easy to understand way. Definitely fulfilled your remit of bringing space down to earth for everyday people!! Well done

All I can do is just repeat the praise of others here. This was an excellent video. I can't wait for the first ever launch of the Big Effing Rocket!

Dude. Thank you.

Great video, Irish fan

On the topic of fuels, I got to wondering if methanol is a viable option for rocket fuel. It's higher density and higher boiling point than methane, and it carries some of its own oxygen. I think it burns pretty cleanly as well. I'm sure someone's thought about this and there's a reason it's not commonly used, but I haven't thought of it yet.

You make the best videos on YouTube. Period.

Great video.

I've come here from "Our Ludicrous Future" podcast. It finally happened! Now you'll have some more leeway in your weekly banter!

Incredible interesting video. I watched video 2 times and paid high attention to it. Thank you! Great video

Here take this comment for the algorythm

I think an important thing about rocket engines and fuel used, at least for manned flight is escapability in case of worse case scenario rocket failure: 1.The Saturn V there was the combination of the Rubber Room underground and a pretty agressive launch abort system on top. Estimated launch pad explosion size 1/2 kT mainly from to the second stage due to fuel used in various stages and the amount in each stage. In other words RP-1 on the first stage was partially a choice of making the worse case rocket failure more escapable. 2.The Space Shuttle we all know doomed, worse design from a safety standpoint ever. When you are strapped on to the side of the main fuel tank, no need to even calculate. However due to the altitude of the Challenger, the explosion happened at the most survivable point (high enough to where the explosion basically expands out into space as opposed to confined by the atmosphere enough to necessarily whack you with a lethal blow, plus a lot of the fuel has burned off, but moving slowly enough to where you don't burn up from atmospheric friction), which is why the astronaut bodies recovered showed they manually turned on their emergency oxygen supplies and breathed until impact with the ocean. 3. The Falcon 9 easy enough to escape from. (Granted your capsule does not spontaneously explode, which I am sure they will figure out.) 4. The SpaceX Super Heavy / Starship does not seem to have a launch abort system. This is curious. The best Reddit post on this I could find suggested the worse case scenario blast would be around 16 kT due to fuel used in both stages, so a little larger than Hiroshima. I came up with there is nearly 25 kT worth of methane onboard, but it won't all instantly flash over; there will be some fall through. I just didn't know how much fall through to calculate for, which is why I mention somebody else's calculation. I was wondering if you can get a better estimation and maybe even delve in more in general to the survivability of a Super Heavy / Starship failure at various points in the mission?

This is a good rocketry 101 video. I remember Scott Manley talking about rocket plumbing and touching most of these subjects. But having a deep dive on the Raptor and why it's pretty awesome was great, thanks!

Brilliant! Thank-you!

when you started listing the numbers, I skipped through the video.. it's just not that interesting to talk through a table of data and saying each number out loud

awesome!! simply awesome!

Excellent and thorough review. Thank you.

This is amazing. Simplified and well explained.

Various rockets have different numbers of engines so a flight number is one parameter, but you also want number of engines flying. For example, five F-1s flew on each Saturn V, so 85 engines flew in total. Shuttles had three RS-25s, so there were 435 engine flights. Here Merlins win because ten of them fly on every Falcon 9, so they have 710 engine flights -- and counting.

Only way this could have been better would have be more space suit. Excellent work!

What an effort! And getting humans to mars?: Atomics.

Hey mate, easily your best video ever.

I generally enjoy your videos, but this one is on a whole new level in terms of presentation, information and energy. If I was Elon Musk I would figure out a way to get you on my team. Brilliant job!

Great video and very informative overview.

Finally got around to watching this video and now I can share everything I learned with my friends. Or maybe that isn't such a good idea...

Did Elon also pay you to make this video? You and your shill channel are nauseating to watch.

I was told that the Raptor engine used a mixture of kerosene or diesel fuel and chilled oxygen. It's news to me that they actually use the methane gas or chilled methane, learn something new every day.

Solid work Tim! Thanks for an awesome video. Loved the length and enjoyed the deep dive.

you are not an astronaut.

You are not a butterrootman32

the merlin is like ironman in end game

Excellent Excellent video. Thank you so much for doing this ... a nd putting together such an easily understood and comprehensive Video Really really great work!

They want methane because this can be easily made on Mars for the return trip. So Methane is crucial.


49 minutes? went by in a flash. This is a quality video, scarce in youtube.

Would love to know the animation software you used.

Somehow I overlooked how long you planned to talk. Thanks for mentioning it.

Ive machined sx500 once, it wasnt all that difficult

Actually looks more like a knight

you did a great job on boiling down a multi-domain field so everyone can undestand it !

Now do a video about Gateway

Saying the hydrogen is plentiful is like saying diamonds are plentiful since we have coal.

+Everyday Astronaut Nope. Since we aren't talking about elemental hydrogen, nor living in most of the Universe. We are talking about gaseous hydrogen on Earth, and there isn't much of it. Just like carbon is the fourth most common element, but diamonds are rare (at least here). Or since Methane is just Hydrogen, and Carbon, the first and fourth most plentiful elements in the Universe, does that make it more plentiful than Hydrogen (gas) since a greater percentage of the universe can be converted into fuel? Once you are talking about converting it from other substances that we DO have, it becomes a question of energy required, etc.

Wait what. Is the most common element in the universe not plentiful enough?

very good done very well and even though most won't understand it even those that will not understand it will still watch it ! NICE !

Without doubt a fantastic video. Didn’t hear about one important factor, hydrogen embrittlement.

Why doesn't methane suffer from coking like RP1 does? I thought RP1 suffered from coking because it's carbon based. Methane is also carbon based so I would expect it to have the same coking issue.

In principle, all hydrocarbons, including methane, coke, but heavier hydrocarbons coke more. _Experimental Investigation of Thermally-Induced Carbon Deposits in Methane and LNG Flows_, Brian B Brady , 2018 Recent interest in the use of methane and liquefied natural gas (LNG) as fuels in bipropellant rocket engines has highlighted the shortage of applicable data on their thermal decomposition and potential for depositing carbon when used for the regenerative cooling of thrust chambers. To address some of the concerns likely to be faced in the development, certification, and/or reuse of methane/LNG-fueled engines, additional data are needed. To help meet those needs, The Aerospace Corporation has developed an experimental apparatus to investigate fuel decomposition and carbon deposition in a circular channel subjected to asymmetric heating representative of actual engine conditions. A copper test section is fitted between an isothermally heated copper block and an unheated support of refractory ceramic insulation. Cryogenic methane, with and without LNG components added, is driven through the test section at high pressure as the heated block is lowered into contact. Test pressures have exceeded 22 MPa (3200 psi). With the copper block heated to temperatures above 600°C (1100°F), the fuel flow exits the test section as a supercritical fluid. *Following a test, analysis of interior surfaces showed minor-to-moderate increases in surface carbon*, significant increases in copper oxidation, and changes to the surface morphology. Analysis of effluent gas samples revealed time varying compositions with species resulting from fuel decomposition. Preliminary data are presented for a pure methane flow and a mixture with 10 percent propane added.

+Everyday Astronaut So that means there won't be a problem with the methane coking with their perspiration TPS like some have suggested.

Those a long long long complex chain of carbon atoms in RP-1 and those bond

I'll go with the Merlin, strictly based on stats given, until Blue Origin and SpaceX both have their new engines proven,

I can't believe I just finished the whole thing. Now back to homework

Comparing the F1 to the others needs more context. It was built for one job which it did wonderfully. Cost was not a consideration at all nor was reuse even talked about.

Fantastic video.

Mars..... Why always about humans on Mars. Now making fuel on the moon or using comets will eventually be very important.

Listened to it twice, but I got a lot more by watching a third time. Awesome diagrams. Loved the fathom joke :)

A simply brilliant video Tim. You should be proud.

You just insulted the Holy Grail.

This video is OMFG AMAZEBALZZZ LAZERPEWPEWPEW AMAZING WTF. Seriously dude, cheers for this video. AMAZING work.

How have I only just found your video! I’m 7 mins in and already subbed, love this already. Woohoo best feeling finding a great creator!

I don’t know if anyone touched on this or not but hasn’t the F1 failed before? Apollo 4 with 2 engines failed?

great video, thanks for making it Tim!

This is an incredible video. I've watched a lot of videos and looked at a ton of articles on rocket engines and this really takes the cake. You killed it Tim. Nice work.

How did it work out that 1 atm is the same as 1m, that’s not how I remember it from diving

+Marcus D For water on earth, pressure increases by 1 atm for each 10 m of depth. P [Pa=N/m^2]= rho[kg/m^3] * g [m/s^2] * h [m] 1 atm is approximately 10^5 Pa rho, density of water = 10^3 kg/m^3 g=9.8 m/s^2

+Everyday Astronaut That's wild, I just never realized the coincidence before, I think we always worked in ft. when I dove. Really great video btw! :thumbsup

I didn’t work it out. I looked it up with a calculator online

I’d be interested to figure out what I could do with 1000 dollars worth of thrust. What could you do with 1 kN of thrust?

Maybe wash my house with a really wicked pressure washer

Way too many ads JR

I worked 60-80 hours a week for three months on this video, drove 24 hours each way to shoot in front of StarHopper, did 3D animations that took hours to render, didn’t sleep because I’d wait for renders to finish so I could do the next section, wrote 24 pages of script, fact checked it with several industry experts, worked on airplanes while traveling and you’re upset about a few ads

Massive video but very easy to understand the info. Very well done, thank you!

One of your BEST videos ever for us rocket nerds !!!!

Your best vid yet. Thank you for this, it's so informative, and fun learn about this stuff, in this format.

Awesome. Just my kind of video. Long, very well explained and full of data. Congratulations.

How will spacex maintain 7000 satellites in Leo without them crashing into the earth after a few years?

They have small solar powered ion thrusters which can counteract atmospheric drag. Since they have very high specific impulse, a few kilograms of propellant will last many years.

how about something on nuclear engines. this just popped up: and the picture is obviously from this paper from 2014: Obviously, work and research have continued since then. It has quite a good explanation of how two different nuclear engines work. One of the design ideas is that these crafts include artificial gravity. (I think Spacex will fail to get to Mars if they do not add AG to their Starship) For that reason they are interesting even aside from the rocket engines. You will note that the designs starting on page 4 start with the least costly and then on page 18 they go through all the possible designs increasing on budget available. From what research has been done (not enough), it seems that Mars gravity may be reasonably healthy, while Moon gravity is not. My thought is that the Moon may be the least expensive place to test artificial gravity, either with a large merry go round style rotating habitat or with a habitat on a circular set of rails (please make the rails farther apart than the width of two horse butts that all earth trains are based on). Anyway, interesting stuff people may be interested in.


I really enjoyed this video from beginning to end. Well done!

Wow, Amazing good video. I almost feel like a rocket scientist now.

Great video, Tim! Thanks for the time, energy and love you put into these videos. I now understand rocket engines better than I ever have!

Youtube: (Solving-Apollo-Enigma-1)  & (Solving-Apollo-Enigma-2)  & stop fooling people!!!

"IF it lives up to it's hype..." Hard to live up to Elon hype...

Waiting for that rocket pollution video :D

Cannot wait for that full video mentioned at 6:01 :-) Woo!

Amazing video!! I think this is the best video on rocket engines! You rock Tim!

This video has the right stuff. Great work, Tim!


nice work Mr Astronaut

Noup Russian engine is the kind of engine.

Excelent video!!!!

Now that was an impressive video...

They say about normal stuff that "it's not rocket science".....well this is literally rocket science. Even though I had a hard time understanding some of the material, i'm actually proud of myself for following as much as did.

35:26 So why does the F-1's baby 70 bar chamber pressure have the most total thrust at 6.77 MN? It is because it has a large nozzle area.

Awesome work! Kindest compliments for this HUGE amount of work

I just stumbled upon your channel by chance and can only say: WOW! - Well done! - You made an extremely complex thing accessible. What a really good video. Big thanks! (...and of course I subscribed... ;-))

The RD-170/171 has been launched into space more than 80 times. I certainly has been used a lot more than the Raptor or BE4. It seems strange to leave it out.

This engine runs on... "Efficiency".

Exellente video Tim. Bravo !

When you color code try to remember that a significant % of people are COLOR BLIND!!!

Great Video! i suggest that at min: 42.30 u multiply the flight record number with the amount of enginges used each flight. making the merlin the king with 71*9 flights.

Great work!

33:30 FACTUAL ERROR! RD-170 and its swivelling nozzle variant RD-171 flew QUITE A LOT (84 launches to be exact) as the first stage engine of Zenit rocket family. Look it up!

One Video that had all the videos and tuts I watched in the last few years delivered in one package... simply awesome...

You really should not have put the definition of fathom up, it would be funny to see how many people would have got that joke!

The most advanced rocket to date can be fueled by cow farts. And you woldn't need that many cows. It's amazing.

is one of your eye green and one black?

Amazing video! Subscribed!

This is the first of your videos that I've encountered and I have to say it is extremely high quality and informative. Although I knew most of the information you were explaining (I've been following rocket design since the '60) your video made complex subjects very accessible. And, yes, I did learn some new things too. Thank you.

This technology is so inefficient because of all the heat loss out of the the exhaust. The sad thing is that the heat can be converted into energy when using the correct engine, The NIKOLA Tesla turbine, and the his vacuum and propulsion patent attached together on the same shaft...

wonder how long it is going to be before the USA blames Russia for stealing their closed loop design.....Russia have the best engineers.....period..!!!

Exist it 3 gaz combustion ? or more ?

Congratulations! And thank you.

Last time i commented on your video you had missed the launch of the second falcon heavy. But this video has fully redeemed you in my eyes.

I can't even imagine how you have access to all this information or even know where to look ... bravo sir, bravo!

it's the stars or the grave Doing it for mankind lmao


If you store a gallon of water in an unpressurized bucket it will supply 2 people for a day preventing any dehydration problems...

honestly with it being elon. he probably chose methane for the simple fact of making a rocket fart XD

methane=cow farts

What a wonderfully informative video!

I have a precharged pneumatic airgun (fancy pellet rifle) that stores almost 300 bar (4000 psi.) of air pressure. :-)

So the raptor engine is powered by cow farts?

Methane? I can help provide some fuel!

Fantastic video!!!! Love your work and if you ever find yourself in Perth Western Australia we would love to have you on the podcast :)

god, how did you become to be so smart?

f1 one is king, f1 is God.

The F1 was truly a FANTASTIC engine, *STILL TODAY (2019)!* stacking up to all these new engines respectably, & in every metric? Wow

Watched the thing things. Final comment: An absolute masterpiece.

Yes, of course it's worth the effort. Economics is absolutely driving our space endeavors. What we do with the ISS is entirely underpinned by the cost of every pound of cargo and personnel sent up there. Until we get a hyrbrid Space plane style horizontal take off vehicle that mitigates both the G force stresses as well as providing the fuel efficiencies of not needing a rocket system until you're already much further off the ground and ready for burn, then of course the Raptor is king. If it performs as efficiently as Elon is trying for, because for now, we are still stuck with vertical launch rocket delivery

49min video? Yes please!

The closed cycle is like a 4 stroke gasoline engine? Right?

Father- “It’s not rocket science.” Kid- “Yes it is.”

Amazing video. Kept my attention the whole time.

Great vid! Wonderful info and the info models were very well done!

Tim this is by far my favorite video you've ever made. I love this so much. I've watched you talk about this on twitter and have seen the sneek peaks of the animations, and you've blown me away. Please don't fear longer videos I know you worry, but we love the detail and depth of explanation. Keep up the amazing work. :-)

Methane powered...

Why did you bring up the Hindenburg and hydrogen when it has been proven it was the coating on the skin that caused the conflagration? The coating was very close to solid rocket fuel.

+Everyday Astronaut lucky for England the Germans did not realize they had the formula for solid fuel at hand.

You know. A lot of people have brought that up, it doesn’t take away from the fact that regardless, hydrogen is flammable

#5 engine (center engine) shut down during flight on Apollo 13. No cause was determined bc, well... They never inspected it after flight.

That was a J-2. No F-1 shut down

Wow! That's an excellent, highly educational video! Kudos.

No, this is not a very very long video. It is 49 minutes, and while it is longer than the average 10 minute video, it is much shorter than the 5+ hour videos that exist out there

Boosted by wet farts?

28:01 ALERT ALERT, SOMEBODY DOES NOT KNOW WHAT HE IS TALKING ABOUT :) I will stop there to not commit a huge error in your next video telling what "you think to know" over a topic that you surely did not invested much time researching. Alumina and Chlorine are the emissions we need to pay attention, then we have soot, carbon dioxide and for last "water", but even if we focus in water (which you would not find any conclusive study about what you claim) you will find out that a methane rocket would emit more water than a hydrogen rocket, due the difference in efficiency and the mix ratio. Second.. I am notice a huge bias forward Elon´s fuel choice without a complete benefit/drawback list, this will prevent you to make a good and neutral research. BTW, great video, I can see all the work invested in the making, good job! That is why I am subscribe.

Thought I was having a flashback at 9:00

Great video Tim, your best yet! Question: Is the cost per engine the cost of manufacture or the "retail" cost?

The opposite of dense is rare. Love your work!!! So much!

The most informative 50 minutes I ever spent on YouTube. Thank you.

As an economist, what really blew my mind was the >300 times improvement in $/kN/flight metric (compared to the F1) that the Raptor aims for. That is a game changer. This opens up space to low-ROI and/or high financial risk missions. Musk will be making money hand over fist if he pulls it off. And we will all benefit hugely in yet-undreamed-of ways - think Industrial Revolution or bigger...

how about the economics of terrestrial methane via fracking? i'd imagine thats more of a consideration than synthesizing it on mars

maybe something also to consider on your environmental impact video


I think I just thought of an idea to increase momentum/energy but not sure. I'll check some stuff out and see if it's possible. I mean the initial take off is most the energy, but there is an obvious way to get the rocket to upward movement without having to carry the fuel to do it.

40:05 please use significant figures!

Tim, your work here is fantastic. Thank you. I love space, rockets and exploration, but ... yes here comes the but ... my reaction to Musk is that he is a genius who has built a amaxing, beautiful, elegant system to 99%, but the 1% which remains sinks the whole thing. That 1% is why? I'm an astrophysics major who switched to economics and went on to manage billions of dollars of investment portfolios. I've also served in a state legislature. The reason we cancelled Apollo is the same reason Musk's Occupy Mars is an amazingly conceived disaster. Mars is a low G, no oxygen, irradiated, toxic soil, bitter cold shithole millions of miles from Earth. It has no particular concentration of resources. There is no there there. The area of the uninhabited Earth is larger than Mars. Musk's diss of Bezos' LEO colonies must have been conceived in a room with no mirrors. The reality is that it would be easier to build a city for 1,000,000 in the middle of the ocean than Mars or LEO. For that matter the Arctics, deserts, Wyoming, the Chernobyl evacuation zone, inside the Fukushima reactor building would all be vastly superior to Mars or LEO. The idea of us destroying Earth beyond the current state of Mars, the Moon, Venus, Ceres, LEO is idiotic. Taking carbon levels to poison and then detonating every nuke on Earth would still leave an Earth an easier repair job than terraforming Mars ... by orders of magnitude. The 'we have to be interplanetary diversify from Apocalypse Earth extinction' is idiotic, go bury 10,000 human on Earth as a recovery colony, they would totally have a better existence than the poor fools buried in caves on Mars or the Moon. The real hard sci fi is that humans are fragile biologics evolved to live on Earth. Space isn't for us. If anyone colonizes the Solar System it will be robots we and our AI intelligently design for the exploiting the particular resource/location worth exploiting. We have a population peak on Earth staring us down. Space needs to serve these daunting challenges. It is not escapism literally or figuratively. Solving fusion, or building space solar, or educating or connecting the world at near zero marginal cost is noble. Bill and Melinda Gates' toilets and malaria initiatives are more worthy than Bezos' LEO colonies or Musk's Martian graveyard.

1:44 Thanks for telling me, got school in just 30 minutes

0:10 Remember kids: "Objects in mirror are close than they appear"

So what do we know about the mystery metal? Nickle alloy?

Out of the park one this one Tim. Worth the wait.

why don't you just work for SpaceX or NASA?

Awesome video brother, very fascinating, we going to mars in 10!!!!(:

I swear this text in the mirror of the car in the us triggers me every time I see it as an european. Looks so wrong, like never putting off the protective foil a new device comes with.

Am i the only one that notices your Buran t-shirt?

Thrust:weight ratio of engine is interesting. Even more interesting would be a metric that includes the weight of the fuel & oxygen needed to make that thrust.

The thrust to weight ratio of the merlin makes it more optimal for short flights. If i want to explore a planetary system i'd probably pick it.

Next time please make some video of hyperdrive engines.

Don't forget the aerospike engine!

one day there will be the time when they are old and it will be abit of a gamble to light the candle

Brilliant. Deep. Joyful. Oh... If I only can press 10 thumbs-up at once... Or even 100?

One of the most informative videos I've ever seen on ANY subject. Awesomely-explained! Don't fret at all about the length of the video, there was never a dull moment! I especially enjoy the information about ISRU and the Sabatier process. Great stuff. Of course I'm subscribed.

Good job professor!

Great work Tim! Thanks

I just wonder woudn't it make sense to develop a more effecient interstellar engine once you get off the planet orbit?

Hey Tim Dodd, I think you might be in NASA’s new video at 2 minutes and 26 seconds:

Increase in water pressure is exponential as you go deeper, not linear

Yeah that’s fine

Thank you for making this!

I am only 2.5 minutes into the video, and yeah, do not be sorry for making this a long video, I am very much okay with that!

14:27 Isn't Hydrogen harder to contain because it has a smaller size, rather than a lower density?

This should be trending.

This is an excellent video. Well documented and well animated. Also, your voice tone is always pleasing and never annoying. It is obvious you have worked very hard on this and I commend you for making quality video content.

Thanks, do you recommend any book for learning more about that?

liquid fuels work well with full gravity, gaseous fuels are better suited in microgravity working environments.

Wow! Finally no BS. :)

GREAT VIDEO!  Brought me up-to-date on the modern types of rocket engines.  I have heard the terms, "staged-combustion cycle" but really didn't have an understanding of them.  My first rocket engine designs were in high school...about 60 years ago!  They were pressure-fed, non-flight-weight hypergolic (aniline/RFNA), designed to give me experience.  They worked, but my subsequent aerospace career didn't involve engine design.  Will be looking forward to viewing your website!

The Hindenburg only used hydrogen because the US didn't want sell helium to Germany at the time.

This is way above 4th grader understanding- so I have to wonder how it is you got 26K "likes" as of this writing? I didn't know there were that many smart people left. I "Liked" BTW. Just sayin'.

how about wankel rotary engine methane rocket hybrid ?

33:25 - also the huge problem with this comparison is that you didn't mention or include the total volume and mass of each engine. The F1 engine has the highest thrust, but it is considerably larger. Yes you included the thrust:weight ratio, but that still doesn't give a good depiction of how offset the info is if you don't include the actual mass and dimensions of each system.

Congratulations Tim for the great work! I reallly enjoyed the whole video. I've never seen the price-trust comparison and I think that was really cool. My only comment is about RD-180 - is this the real price of the engine, or the price the US pays to get it. Cuz my guess is they do not coincide. Also, I kind of miss the RD-107 from the picture. I know it's hard to compare all the known rockets, but after all, the RD-107 series are pretty popular engines. Anyway, thank you for the great video and good luck with all your projects.

SpaceX is at least two years ahead of anybody.

For comparison, need to put in nitromethane :) Excellent video.

nice we will have rockets running on farts, I don't wanna be near the thing when it takes of without a air filter .

0:58 "We're going to see why SpaceX chose methane" Me, an intellectual: the answer is quite simple. It's density is 420 g/L.

Great video Tim! The diagrams really help.

It doesn't occur to anyone that you can't have a launch site right next to a public road?

Pete the cat sent me here. Thanks Pete Great video!

Never trust Melon Husks, with all the Tesla fraud and the Boring company fraud. Melon Husks may end Space Age for all of humanity with his promises.

Fantastic video Tim with one caveat: You spread the false impression that the Hindenburg disaster was the result of hydrogen gas use. It is known that the skin of the airship was covered in a dope (aircraft fabric coating/paint) with properties far from flame retardant. The skin ignited - look at the footage. The footage in this very video. As you well know hydrogen is a gas that is lighter than air. When it combusts at sea level and low pressure it will behave like that puff of natural gas (methane, hmm, another rocket fuel?) coming out of the typical stove top in a kitchen, or, perhaps, that gas-fired fireplace. It goes "wumpf" and all goes up at once. Flashing over is another way to say it. The Hindenburg did not do that. As you pointed out in this video hydrogen is a sneaky sneaky element. It likes to leak and get away. So, being so much lighter than air, once the hydrogen "tanks" ruptured the gas would have rapidly gone up (lighter than air) and away. It would not stay close the aircraft pouring fuel to the flame like a blowtorch. One more thing I'm sure you know. Hydrogen flame is very faint. In full sun, difficult to see in fact. The Hindenburg disaster took place very late in the day so it was darker, but, the film stock at the time was not very good in low light*. The huge flames visible would most likely not be "pure" hydrogen burning. I'll stipulate that under the conditions of the skin fire there was some hydrogen combustion. It simply was not the cause of the tragedy and a helium filled-Hindenburg would have caught fire and lost its skin in the same way. Finally, I'll grant you that the actual cause of ignition and the role of both hydrogen and the skin (coating) remain a subject of hot debate. However, it is safe to say that it did not catch fire and burn up because of hydrogen (the role of the gas after ignition is what remains uncertain). *Arguments are made that the sensitivity of the film at the time to the emission spectrum of hydrogen flame (wavelengths of light) explain the bright reproduction of the fire scenes. While that may be true the overall sensitivity was so low I don't think this is a credible explanation for the bright fire scenes. FWIW I'm a trained professional photographer from the film days. Anywho, none of this is meant to take away from the huge and praiseworthy effort you put into the overall video. It is a very complex subject and while my brain is full I feel I'm a bit better equipped to understand the emerging rocket propulsion systems thanks to you!

What kind of alloy did the Soviets use @11:30 ?

i watched this video twice


At 32:00, your comparison of engines. Are the different pictures to scale?

They’re to scale.

I think the F1 engine should have been at 98.8 because of the center engine failing just after take off of Apollo 13.

Nope. A j-2 shut down

Great Video! Would like to see a video about the SABRE engine and the Skylon Spaceship.

Wow! What an amazing video! Very well done, and I couldn't believe it was 49 mins.


Everyday Astronaut the Soviets used Stalinium in their closed cycle engines )))

stupid question from an amateur here, but has anyone ever tried to eliminate the preburn cycle entirely? Maybe using something like an EM induced cylindrical impellor (kind of like an inverse auger) with a progressive pitch increase within the fuel and lox lines themselves? i have no idea if the hydrodynamic properties of liquid methane or oxidizers would allow it to work, but if it did, no extra seals to fail and no complex fuel routing. But like I said, I'm no professional, just a thought from an amateur inventor.

EA can u review the ksp new breaking ground expansion?

This is the finest rocketry tutorial and technology comparison video that I have seen. E.A. has struck just the right level for teaching his enthusiast audience. Thanks for this, Tim!

I also have another question. What are the BTUs of those different fuels?

your cost considerations do not take into account the ISP which is a HUGE factor, if not the most important. There is no use to have a super cheap /kN engine with terrible ISP as to launch the same payload (especially on a high DV mission like mars) with require exponentially more fuel (and rocket size, and more engines to lift that fuel)

Epstein drive is better

21:20 the diagram says methane but you say methalox, which is it?

The repeating kick snare in the music is very distracting. If you must use music, it should be low pitch and ambient. Remember that music that is nice to listen to is not appropriate for background music. Or, you could simply go with no music at all (when talking).

I don't know whether this has been said before, but Tim Dodds is a Steely Eyed Missle Man. Superb video.

I have spent an entire life working up to the point where I found and watched this video - the BEGINNING portions of this video.

Fantastic video - lots of information about a fascinating subject and explained clearly for all. Thank you!

Space X has done nothing that was not done in the 60's. Mucking around with fuels etc only impresses low information fan boys.

Pfft...It's not all that technical. You carry on like it's brain surgery or something.

Great job

Tap-off cycle ,expander cycle ,electric turbopumps?

Is this Rocket Science for Dummies?

There's a tiny rocket forcing the fuel out!!!!

I hope greed is gone in 2219.

TL:DR RD-25s where a scam that cost reuse them, then it would have to just replace. They did the rebuilds anyway for the swag credit of "Reusable" I'm sure someone already told you this, but the RD-25 was only technically reusable. because the rebuild of an RD-25 (Manditory each flight) was more expensive then a new one. This is part of why the shuttle program is considered a failure to most of us in the field. For the record I worked for SpaceX for a few years. so I'm saying that from personnel experience. There where so many issues with the shuttle program and not all of them where even bad design. For instance, the Air Force basically conned nasa into making the shuttle so big. The original desgn was great and propose build. But the Air Force wanted a HUGE cargo bay. And they offerd to pay half the cost of the program. But NASA never saw a single penny. So NASA had to scrap there plans for around 4 moon missions a year, an huge space station and a fleet or orbital tugs. All because the airfoce scammed them. they lost half there funding and all they had to show was a very inefficient system.

Wrong on the Saturn 5 engine. The center engine on Apollo 13 shut down about a minute and a half into the launch.

I was hoping to live in a warp-drive era

Fantastic video!

Incredible video man!

Pretty sure the F1 had an in flight failure, actually two after the computer turned off the wrong one.

​+Everyday Astronaut Ahh, second stage, quite right. Perhaps next time I will use google to verify my faulty memory before calling you out and making a fool of myself. Well who am I kidding what's the fun in that?

That was a J-2

i have seen the landings on the rafts out in the ocean .... space x is fake...never happen couldnt happen its a farce ....

Is it sad that I am using this to find out how to launch my own rocket? Yes? ok.

Just came upon your video by the magic of Google Algorithm :-) Boy was I thrilled by the best "Rocket Science" discourse in less than an hour. It is just great to be alive in this era where sharing of such incredible amount of info and knowledge is just at the touch of few buttons literally at the speed of light "C". Rama

Thank You. Good video. If you have any more energy left it would be interesting to see how Propane fits between RP-1 & Methane. Zero cryogenics Higher density lower tank pressures. Probably lower chamber material temperatures Almost as available as methane. Pipelines to the launch site. I don't know about manufacturability on Mars

Great video. Now I'd like like to know about the smallest rocket engines. Mono Propellant, Bi-Propellant, Hall-Effect, Xenon, Krypton, electric propulsion etc.

I learned more in the last 42 minutes than in all the hours I've spent reading over years. Excellent video. Top of class.

That was incredible EDA, great work man.

You rock. I love your enthusiasm and pretty much everything you're doing. This video is just fantastic, and the fact that you get input from your Patreon supporters is just wonderful and I think it shows, the video touches on every subject that it needed to without going too far.. Keep it up my dude.

@Everyday Astronaut - Is there a better statistic than ISP used in aerospace? ISP only talks about the effectiveness of the fuel generating thrust by dividing the thrust output by mass flow of the fuel used to generate that thrust. It indicates the efficiency of your fuel and combustion system, but totally neglects the mass of the rocket engine itself, fuel / oxidizer tanks, etc. It seems to neglect the basic issue that you really only care how much your rocket can lift that isn't the rocket itself. I would like to see the dimensionless number be [mass of rocket minus payload] divided by [maximum payload mass that can be delivered to a given orbit], but I haven't seen people use that number for comparisons. I've heard--but haven't seen the numbers in detail--that SpaceX went Methane over Hydrogen, because they realized that the Methane tanks would be so much smaller and lighter than Hydrogen tanks, and it would so greatly simplify the design of the Raptor (further reducing the engine mass) that it more than makes up for the reduced ISP. If that is true, why have everyone been building hydrogen powered rockets for so long? If ISP is the be-all end-all, then some may ask why are Ion / Plasma engines are not in wide use despite having ISP values orders of magnitude higher than any chemical rocket engine? Besides not being able to generate a lot of thrust, the mass of the engine with all of its shielding and the power generation system (solar arrays or nuclear batteries) make the spacecraft so massive, the little engine can barely accelerate the vehicle. (F=ma => a = F/m) That said, they are the little engines that can, when it comes to deep space missions. Now for the nit-pick: You called the RD-25 engines "reusable" and factored that into the cost, but that only refers to the Shuttle version that is no longer in service. The RD-25D engines for the SLS are now going to be disposable so the potential cost is going to be even more than $27k : kN since they were built for the Shuttle, then modified for SLS (original production cost, plus mod cost).

43:26 "With the F-1 never having shut down at all" But what about the time one engine failed on Apollo 13?

That was a J-2! Why is there 100 comments if this

Ahhh, I miss Physics! Great presentation with great passion and the perfect energy!

The video was excellent, but can we talk about the real pressing matter here? Tims glasses are amazing! They look so dang sharp...

I'd like to see an honest check on the Boca Chica habitants' dealing with Elon's enterprise (see the tiny sarcasm in the choice of words?). All that glitters is not an Enterprise. (Ha ha.)

VIdeo: Hey, watch me! Me: nO. yOuR tOo LoNg!!! Video: 49 minutes later Me: oosp

If RS-25 is so good, why NASA buying Russian RD-180?

What interests me is I hear anti-matter may be the answer too. Small, powerful, high pressure?

Wow, now that was a mouthful of Rocket Science... learned a lot... Thanks!

Hey genius how do you think they work in a vacuum? You think its pushing off itself? Do you know how stupid and against physics. Pure bullshit.

So if you’re sitting on an office chair and you throw a bowling ball.... you’ll move back a decent amount. Are you suggesting that the bowling ball is pushing against the air and that pushes you?... or...

I know you we're referring to the millennials out there but 49 minutes is not long for Rocket Science. Long format videos are key in real understanding. Also quick comment on Flight Records comparing the engines @ 42:24 - Each operational flight record or the number of times each engine has flown isn't accurate, like you said a . For example, the Saturn V missions included 13 total launches, however each Saturn V rocket had 5 x F-1's per flight, that's 65 F-1 Flights. The Space Shuttle has flown 135 times yes, but each flight had 3 x RS-25 engines, so the actual number of flights for this engine exceeds 400 for the RS-25.

had to reread title few times to make sure it wasnt about 40k lol

I’m 25 minutes in and just realized I don’t understand any of this Cool video though

Pure pleasure and joy watching your videos! Keep it up!

American Crap.

C'mon, high pressure -> low pressure It's not rocket science… … …Oh wait

Well done

I loved this video, THANK YOU for all your efforts to produce it.!!!!!!

I just had to comment this video's advert is 'Turn fear into motivation by Chris Hadfield' it was beyond immense!!! That was one of the most inspiring positive 'out of the box' speeches i've heard in decades!!! @whataguy

Simply an amazing video! The simplified graphics were very helpful!

I wonder how these work compared to an aerospike rocket engine.

The 100% reliability number for engines that fly once... well... its a bit dodgy!

my 1st thoght is a battery that is small and then runs out quick but is the boost to start

I'd rather get lost in well explained detail than understand an oversimplification.

Anyway, where's my Moon Base Alpha? How come we haven't colonized Luna, our moon yet? We should have had hotels up there by now!

what about the Flux Capacitor??

Superbe vidéo ! J’ai enfin compris les cycles de combustion des moteurs fusées

Nice to hear you putting Specific Impulse into layman's terms. Clearly a huge amount of work went into this video. It's appreciated; thank-you.

What about the Monopropellent(H2) NERVA engine, developed in the 1970's? From Wikipedea; 333KN thrust, isp(sl) -380, isp (vac) - 850. Test engine fired 1,200 min at full thrust, developing 1100MW of power. The Saturn S-N variant would place 150,000KG to LEO. (2.3 X The Falcon heavy max payload).

I came, I clicked, My mind expanded. Big concepts brilliantly explained.

An F1 shutdown early on the Apollo 13. Brilliant show, I really enjoyed it.

That was a J-2

Wow, great vid, but I kinda zoned out a bit once I noticed your cool different coloured eyes

Hey Tim, you always hear on did the SpaceX live stream that they are chilling the pumps on the upper stage. I'm assuming that means just running cryogenic fuel through them make them cold, but why do they need to do that?

I think the way to describe the Raptor engine "best-balanced" engine, in terms of its specifications.

358 Blue Origin employees disliked this video.

Do you have any tips to become a rocket/space vehicle designer?

Wow this is really a great video. Thanks for all the work and effort!

Impossible not to love this guy. Best communicator ever. Go Tim!!!!!, even Elon pays attention.

Fantastic job and research, keep up the good work. A tough subject that I at least understand to a degree.

However, Russian engineers and Soyusz remain the best in the World!!

That "fathom" joke was deeply humorous.

For the RS-25, are these numbers for the Space Shuttle version or the SLS version?

I think the numbers should be the same

Awesome video! I missed only one thing that would be interesting to consider: the more engines you have on a spacecraft, the higher the likelihood that an engine will fail. In that sense strapping so many Raptor engines together could be a risky proposition.

About one person in 1,387 gave a thumbs down.

An excellent video. Obviously a lot of work and time spent on your part. This will be the first upvote I've given anyone in awhile, but you deserve it. Thankyou, Congratulations, and Well Done.

Incredible video, thank you very much.

Ariane 5's Vulcain engine isn't mentioned, on wikipedia its ISP is at 431s, which seems high, any thought about that ?

This is a great video - building an understanding step by step, introducing the variables one by one, and then connecting all the dots. Great teaching, great diagrams, great data presentation, great delivery and yes - a Raptor video!

Tim, this was fascinating! Thank you.

Футболка супер!

Do you think itd be a cool idea at 19:52 make an 1 hour long loop playing ur music Everyday Astronaut? Its kinda mesmerizing the animation :P

You did a great job with this video. You took some very complex subject matter and made it informative, understandable, and interesting. Thanks.

I like to start my preburner with a lawnmower ripcord.

A design suggestion.. add the Logos of the companies producing the engines to the representations.. i have to remind myself every 30 sec witch one is the Russian.. the US one, and so on.. The names they put in this engines are awful.. kudos to SpaceX for not using initials and a random number(random for us..)

On the F1 reliability. The F1 had problems with pogo oscillations. This nearly tore apart Apollo 6 test flight. On Apollo 13 they had to shut down the center F1 shortly after launch because of pogo I believe. So that should count against its reliability.

+Welyum Yep, you're right. I looked it up again. I always thought it was the F1s. Thanks for enlightening me. That's the way to learn!

The J-2s had problems on these flights, not the F-1s

I am trying to figure out who would down a video like this. Are there that many curmudgeons working for ULA who will down anything nice anyone ever says about SpaceX?

Great video. Fantastic background and put in a way that is easy to understand. I feel like a Rocket Scientist now:) Thank you.

31:20 Thrust : Weight 198:1 for the Merlin Engine that is used in Falcon 9 and Falcon Heavy. And look at every other Rockey Engine, they have no chance. SpaceX For The Win.

Wow we using 6 Oxigen to 1Hydrogen insteed of 1 O to 2 H ? Is this data correct? 1:03 Nvm the chrt is missing the unit it is displayed in gramms, not as anyone would asumme mol. But he explains that later, still small nitpicks your graphs should stand on there own tim. If you do a non comon unit write it down plz. (I mean using gramms without showing the molar mass of the chemical is silly if you do reactions ratios)

Yes that’s correct. Helps offset the massive tanks of hydrogen. You’ll learn more about it in the middle of the video

To only add to the overwhelmingly-positive cacophony of comments: best video yet! Information accessible all in one place - and in ONLY one place! And to echo other comments: you made ISP so simple to understand! Fantastic job! You even got the Elon seal of approval - how cool is THAT?! ;-)

Amazing video man, thank you very much!

Awesome video, EDA!

Amazing video! Thanks mate, i always was curious about how rocket engines work.

Is this the engine that just exploded ? Will finish watching video , have add and sore butt from watching YouTube videos.

So... Raptor is kind of like Ford Focus. You wouldn't call it king but it sales like crazy! However, GT40? Sure, it's expensive, huge, noisy etc. but guess what? I didn't see any Ford Focus posters for car maniacs to hang in their garages.

This was so very informative. Thank you for posting this. The amount of work and effort and research to produce this was phenomenal. Thank you!

Absolutely loved this video. It answered questions I didn’t know I even had. It also gave me a great appreciation for rocket engine design trade offs and economic impacts on cost and operation. Amazing and very well done.

Fantastic video.  Subbed!

Woah, that got deep, fast. Great job condensing all that engineering info down into a 49 minute video. Really explains why rocket engines look so complicated (and cool!).

+Gibacke Nope - that was on O2 tank in the service module that failed

Wow, Elon Musk actually watched this? I didnt think someone as famous as him would be interested in what us commoners watch

+SpankTheMonkey531 I wish every CEO in the world would be like him.

Terrific documentary, very informative. Yes, the raptor engine (theoretically) is a great idea, if it performs as billed. 1 metric not discussed is that Space X Raptor engine is just being designed now, compared to the Russian RD 180 which was created more then 40 years ago. (oh, them Russians - ahead of their time)

Thanks for this video. I worked at SpaceX for almost 8 years, and I still learned something!

+Mike Teves Yes, the Rocket Lab Electron rocket, which resembles a scaled-down Falcon 9, uses battery-powered electric pumps on its little Rutherford engines. The second stage jettisons a discharged battery pack before reaching orbit. This works very well

+PepsiMagt Good point about RD-170/171 flights (e.g. on Zenit). Although the RD-180 is extremely durable, there is no way for it to be recovered at present. It is not restartable, and is much too powerful for retropropulsive landings, even with its degree of throttleability, unless it were on a huge rocket with more than 7 or so such engines. Also, the Atlas V attains much higher energy, at least for unmanned flight profiles, requiring more fuel for re-entry and therefore being much less efficient as a re-usable first stage.

+prusak26 While Tim does a fantastic job, I also think that the Space X people do a great job in live stream, too. Their presentation by definition has to be more scripted, but it certainly is informative and enthusiastic.

+Mike Teves Perhaps on the cold side they could use a superconductive electric pump. They are pumping LOX for crying out loud. The whole purpose of the preburn cycle is to create pressure. These people have been able to pump liquid hydrogen with a superconductive pump. Not sure if the pump design would provide the kind of pressures needed but it would be a starting point.

+PlanetMusk Vlog most people have a negative net worth.

Great video Tim! I was anxiously awaiting this one and you did not disappoint! I've watched it a few times now, really trying to soak up all the information.

Watching this, and at 5:23 I already see this is a clear step by step introduction to rocket engines. Awesome. Watching the rest....

Rocket science for the common man (and woman, of course). Tim, you've made an incredible video here. The quality and quantity of information are perfectly matched: the former with truly excellent illustrations and the latter with perfectly paced, straightforward and engaging presentation. In my subscription list, you now share top spot with @EngelsCoachShop ( It's too late for me to be either an aerospace engineer or a master wheelwright/coachbuilder, but I love to learn--and today I learned a great deal. Thank you!

Yes, probably and probably not.... really was that a question at the end?

This was really helpful, thank you.

did any one notice he have one green eye and the other one is black ?

Great work. Lots of detail. No fluff. Very clear.

methane? cool..... we going to space powered by cow farts .

Fantastic video ! I was glued to the screen.

Love it Tim! Awesome watch. I'm about to start over for watch 2.

F-1 rocket engine, best rocket engine. Reasons: 1: Has never asplote 2: Has never even shut off 3: Big 4: Loud 5: Moon

49 minutes of word salad

the only reason they want to use methane is for bragging rights. "yeah we launch our rockets on farts"

Future rockets will have air intakes.

This video has renewed my faith in humanity. Excellent presentation / graphics / charts / pace... it's like having a chance to visit Tomorrowland.

If this renews your faith in humanity, you have no idea what sorts of other cool stuff we have. How about a material that's more than 200 times stronger than steel, all but immune to heat, can filter carbon out of air, radiation out of water, can be a superconductor, and is made of carbon itself? That's just for starters.

I'm glad you used metric system in your video instead of stupid Imperial system.

Ooooohhhhh... I see a orbital station that harvests Mar's gases and uses it to power the station.

I don't see what's so complicated about these engines. It's not like it's rocket surgery.

I Like Your T-Shirt! @0:45

This is a really cool, informative video. Great job!

Wow. Check out the border wall around that facility. What a waste of time and money. Walls don't work.

It's not hydrogen's low density that makes it hard to contain. It is difficult because hydrogen has extremely low viscosity because of weak inter molecular bonds and small molecule size.

SpaceX will be using methane as a fuel because Elon finds it humorous that his rockets will be going to space through the power of fart lighting.

I like the technical side, but you talk like you're trying to be cool for kids or something... that won't watch this anyway. Just talk clearly and don't let your hipsterness get in the way.

As usual... just awesome.

30 million farts to mars.

Love it

Great video, best explanation of differences I've ever seen. Will be interested to see how it develops. simple. Informative and well done. shared!

Youtube needs a love button more than stupid facebook. What a fantastic video.

You got a new subscriber in me. I've pressed that bell :) Great content

No trust in vacum ! All bs

Буран t-shirt, like from Russia!:)

I finally clicked on this video. You happy now YouTube? Cause i am =)

The Veloci-Raptor looks good to me. Good vid!

All fake!!

Great video, Tim. Worth the effort. Very informative. I now have a better appreciation of what it takes to be a rocket scientist. If anything I'm really nervous about the performance of the raptor engines. Didn't realise how far Elon Musk was pushing the boundaries. Enjoy your vacation. You deserve it.

awesome video. can you discuss aerospikes sometime this century?

Man thanks for the video I actually learned so much.

WOW. This was breathtakingly well done. You’ve managed to inspire and motivate me to put time into studying and exploring this space. No pun intended. I’d love to see more of this type of breakdown content in the future.

18:50 that startup is badass.

Also, the engine COST or $/kN is also relative metric... RD180 that is manufactured by Russia and then sold to American companies costs $25 mil/engine... BUT the same exact engine does NOT cost $25 mil / engine to ROSCOSMOS... Soooo when you calculate the COST, you need to specify what that cost really means... is it acquisition cost or cost of production or something else...

The engine re-usability is a flawed metric here... since all engines could be reused if they were recovered... so F1 and RD180 are reusable... its just they were used on systems (rockets) which were 100% since use...

I was watching this video when you mentioned it was long. At that point.i thought meh ill watch until i am no longer interested. I am now 33 minutes in and completely enthralled

Ahh, just enough delta v to make it. Every kerbal players experience

Honestly i think full flow is a logical decision to reach, the real problem with rocket science is that iteration and innovation cost so much and happen so sparsely that it delays logical conclusions of existing technologies simply because of high cost and lack of return. If this was advantageous to something less expensive like cars it would have been fully designed out decades ago.

Funny how can carry hydrogen in a balloon buy for anything else its expensive!

that was great, especially for someone that is into stem but not particularly into the exact topic! pls do more

Hi Tim, in your price comparison have you used the price of the RD-180 imported to US or the price on the local Russian market?Nice work by the way.

Would be great if you would've included RD-171M and KVD-1 in your overview. And would be glad to watch vids on atomic powered engines like NERVA and RD-0410 projects and its development.

Hey Tim, could you explain why in a closed cycle engine, that RP-1 leads to soot which clogs valves etc. In the combustion chamber, but the same does not occur for methane? I mean methane is still mostly carbon by weight and so should give off a lot of polymers

Thank you Tim that was excellent. Your hard work showed up in quality, depth and accuracy.

Hey the radical Left wants to kill off all the cows because they produce Methane. We could tell them we need the cows to power the rockets...…..

wait a second ... do u have eyes with two differend colours (noticed at 3:30)

y u p

I vastly underestimated the complexity of rocket engines! I thought that at simplest form it would be a throttle valve, a bell-shaped nozzle, and some cooling pipes. BUT ROCKET SCIENCE IS NEVER THAT SIMPLE

why did you not mention the nuclear rocket motor?

Now, this is a quality video! *YouTube's* Always Recommending Me BS Videos that spend over 10min explain 1 simple topic. This on the other actually entertaining and kept my attention unlike the majority of my past instructors back in grade school.


Really excellent content. However, consider purging "crazy", "insane", and "nuts" from your vocabulary. Heard them 'WAYYYyyyyy too often.

This launch will be the biggest fart cloud in history!

Outstanding video! One of my favorite engines will always be the Estes A8-3 LOL! If you ever do a solid rocket engine video would you include this one?

Who dislikes this video...?

Impressive work! This video is amazing, keep it up! :)

You get a thumbs down just for having Russian all over your shirt. You socialist communist little fucktard.

Holy crap.. I know you dont monitize these videos but I feel bad that i dont have the money to buy from your website. But I want to support you some how. This was fantastic and I have to be honest.. its nice that Elon took the time to respond to the video on twitter..

For that case, yes, but how would you rate them if you had unlimited supply of rp1 on Mars ? Did they even know methane can be produced on Mars when half of these engines are designed ? Did they plan to go to mars ? What if you look into going to Moon is it still the best one ? …..

8:15 NO! At least tell us quickly -.-

At some point, this became an accounting problem.

This was one of your best work so far! .... the animation was very helpful and your explanation was simple and easy to understand. I know it probably took a lot of time and work and I appreciate it. Looking forward to more videos like this .

Wow! Thx- (Are you a secret professor at Caltech??). I am impressed!

apollo 13 had a F1 shut down early, while the mission WAS a huge fail, it did get to the moon...

Kudos for Buran t-shirt! )

You mention rocket pollution problems. For a number of years, I was concerned about the ozone damage caused by NOx generated by rockets going up and that they generate during reentry. Finally found the right people at NOAA and talked them into looking at the problem. At the time Reaction Engines proposed Skylon Spaceplane looked like it was the only vehicle that might get down to the cost needed for economical power satellites. A construction rate high enough that it could replace fossil fuels takes a high flight rate, perhaps pushing a million flights per year. Not impossible since it is only around ten days of large aircraft takeoffs. The article they did is here: It looks like we could replace the energy from fossil fuel without causing a billion cases of skin cancer. Because they run "rich," that is excess hydrogen, hydrogen engines make very little NOx. Most of the NOx with Skylon comes from the reentry shock. That's not the case for hydrocarbon burning engines where air mixes with the rocket exhaust. But how much damage they will do to the ozone at high flight rates has not been studied. The NOAA people are willing to do the study but they will need input from the rocket folks.

Your Buran T-shirt is just cool. And a WONDERFUL video....

but what about the aerospike?

do you have heterochromia?

This video is awesome, even made sense to an idiot like me

I rarely say this. This is a great amazing video... Makes me want to go into rocket engine engineering.

I can't wait for the Raptor to be implemented in KSP. The KS-25 is the current king, since it's tiny, efficient, powerful, and has a high vectoring range. The Raptor is smaller, more powerful, and just as efficient. It'll probably be cheaper too.

Tell AOC you got the answer for cow farts, use them for rocket fuel xD

That's some rocket science right there!

Is there a reason you chose to use 300 bar measurement instead of PSI to describe the pressure in the turbo pump? I may not fully understand the difference between bar and psi

They’re the same. Bar is just metric

Big ups

Is the Merlin Vacuum engine the same engine as the engines used on the reusable 1st stage ?

Yes, except for the way bigger nozzle

FYI on the F-1 Engine (if I remember correctly) they were test fired before being shipped to the NASA New Orleans Facility where the S1-C was constructed. Because of the Carbon Coking they needed to Flush the engine with some serious stuff (trichloroethylene). Fun Fact the Turbopump exhaust on the F-1 was fed through a Heat Exchanger and the cooled exhaust was then fed into the skirt of the engine to help keep the engine from melting from the high combustion temperatures. That is why when a F-1 would fire you would get a dark exhaust closer to the engine then the bright yellow further out. (As far as I remember)

So YT is going to make us watch TWO VIDEOS now and hassle other sites by removing revenue opportunities? I dont think so.

phenomenally excellent Tim - many thanks :-)

If you are planning to travel the solar system, methane is everywhere and easy to make in a pinch.

A true masterclass of Youtube content. Well done.

Title implies 'Yes or No' question, but video is 50 minuts long.. LOL

Now THIS is a quality rocket video. Amazing! I learned so much.

жалко шо не шарю по англ

Would have been good to see the energy level per Liter in your fuel analysis breakdown as well. Great job on the video though, thanks!!

Also, when considering 'flight record' in your engine comparison it would have been good to calculate actual engines fired on the rockets rather than just how many flights used that type of engine because of the large differences in engine count between these rockets.

Cool video, except, @35:41 mark, you say that higher chamber pressure usually means bigger thrust, yet, the F-1, with like 3x thrust of the next best one, has the lowest chamber pressure of them all...... To me it looks like you looked for positive traits of the high-pressure tanks, because SpaceX new engine is ridiculously highly pressured (@270bar). Actually lower pressure seems far better, thrust wise, and is safer, the tank weights less, but you of course did not mention any of that. What you meant most likely, is that pressure gives better thrust for a given type of engine, like methane engine with higher pressure chamber = better thrust, yes, but they way you said it, no.

Why are you wearing a hat inside?

tons of good info in this vid. thanks

Excellent episode! Thanks!

Who said rocket science was complicated? It just needs some explaining by Tim.

Bravo !

You are crushing it with these videos. Represent Iowa! Woot Woot!

+alxo82 Both Tim Dodd and Harald Ferron J Pentad are correct. Ocean diving adds 1 BAR every 10 meters or 33 ft., so 301 BAR at 3000 meters.

+Allen Loser oh ok. Let's see what Tim cooks up for us to understand this well. I hope he answers the above question.

+Emmanuel Mahuni Perhaps I misunderstood "Electron" engine. I presumed that you were referring to a plasma engine which relies upon accelerating charged particles to near light speed as reaction mass.

+Allen Loser No, I don't mean using the Electron engine per se (I hope I understood your answer well enough), I meant the turbo pump section. The Raptor is fine with their design, they are genius, though the Electron engine has not yet been talked about by Tim, it made sense to me how they could do this from what I now know. It all boils down to one thing I think team Electron has done, which I was asking in that query. It seems like Electron engine is using powerful electric motor(s) that pumps the oxidiser and fuel into the combustion chamber(s). From the looks of things, this cuts off a lot of plumbing and mechanisms, which in turn reduces weight and other complexities and adds finer control to the engine. Since it's an electric motor and uses a battery it means SPACEX can leverage TESLA's core technology and business to create a technology feedback loop. I think SPACEX/TESLA can make a more powerful and better electric motor for it better than Electron Labs. The other wonderful thing is the Electron engine is entirely 3D printed, and because of the lack of turbo pump complexities, it is easier to print and has way way little parts than the conventional rocket engine. So my question is, why isn't Elon Musk doing this? It has been proven to work for a rocket engine, why isn't SPACEX adopting that technology for the Raptor? Is it that the pump isn't powerful enough to produce enough thrust-to-weight ratio?

+Allen Loser No. Not a "StarGate" either. Consider when Ptolemy successfully modeled planetary motion with pretend glass spheres with epicycles and deferents. From then on, "scientists" worked to perfect that model and nothing else. Same today with quantum mechanics, which still has no variable for "awareness factor" from which our brain cells create the illusion of self. Something more fundamental and weird is needed, such as being able to show everything shares a common center and light creates the illusion of separation. Then again, why aren't we considering "particles" as miniature event horizons ? Where do we go from here ?

+Ted Phillips Waiting for warp drive?

+Lucifer The engine which shutdown prematurely was a second stage J-2 engine. You are correct that the POGO oscillations induced would likely have resulted in destruction of the rocket had the engine not shut down. Shutting down is not a failure. Shutting down is desired behavior under the circumstances.

+Emmanuel Mahuni The thrust-to-weight ratio is too low to get off the ground. It is useful only once the spacecraft is in zero-G to produce a tiny acceleration over a long period of time.

So how many rpms do these pumps turn? I have some ideas

Great show - an above average high school student should fully understand. What's your name "average astronaut" ? YOU should teach undergraduate aerospace students.

I've learned a lot about rocket engines in this video than what I've read since I got interested about rockets some 40 years back.

Plus with the fracking of oil with the byproduct of natural gas and no economical way to store it fuel cost would be dirt cheap.

Question. From where do you have the burning temperatur datas? For me it seems inverted. But i'm probably wrong.

Great video. Sounds like the optimal engine for a long obsolete technology. A better stone for the stone age until the military turns loose of their anti-gravity technology such as the TR-3B and we are finally free of wasteful vertical takeoff rocket vehicles.

For a second I thought it was called the Rapture Engine... like someone's planning to escape Earth if they don't get to Heaven lol

Methane? Molecules of Freedom!

Nobody: Elon: We can go in space by farting.

Fascinating video, sir. Thank you very much

And they said Meth was good for nuffin'...oh, Meth-ANE! My bad...

Hey Tim, I hate to pull you up but i believe at least 2 F1 engines shut down early during on Apollo 12 or 14

J-2s failed, not an F-1

Tim ya little fucker! Where have you been? VLogs are getting a bit thin these days! Thought you'd done a Heavens Gate with the Oumuamua and Marshall Applewhite. Starhopper... what's a Happening dude!!!!!!!

If I was an engine designer, I would have used a fuel-rich pre-burner turbopump for the fuel pump (using liquid methane for the fuel to avoid most of the coking problems), with the shaft extending out to a sealed magnetic coupling that would then drive the oxygen pump (to avoid the need of developing expensive and failure prone high-temperature specialty ceramic-metals). The magnetic coupling would ensure that there would not be any possibility of fuel getting into the oxygen flow, and conventional low-temperature metals could be used.

Great Job!

Awesome video.

Good job on this very informative video. But "Fah, fah; Ta, tah", watch your SI units. They don't have plurals. I know that is hard for a Yankee. 1 kiloNewton, 10 kiloNewton, 1000 kiloNewton. 1 kilogram, 10 kilogram, 10,000 kilogram. 1 meter (metre), 10 meter, 10 kilometer. 1000 kilometer-per-hour. Just think of them as sheep or deer. Of course you are free to do whatever you want with miles-per-hour ;)

This question is probably going to get buried in the comments, but I want to ask it anyway....... Is there any discernible reason why SPACE-X is going for the (Essentially) direct ascent approach to Moon/Mars. As opposed to what Science Fiction always told us that there would be a vessel built in space, that would stay in space, and send smaller craft to the surface of each planet. (Similar to the gateway idea I guess?) I am sure the answer is just.... maths, but would be interesting to analyse it.

Fantastic Video !!!


BTW, stood next to Apollo-19 at KSC. Those Rocketdyne F-1 engines are truly massive, and humbling at the same time.

Rocket engine reviews....

Tim, "Awesome video" I've watched it several times. Thank-you :) Since CH4/O2 is the choice for fuel on Moon & Mars refuel. Consider a follow-up companion video with thoughts from Elon on creation and re-fueling Starship.

Nice animated graphics. BTW 49 minutes for science stuff is not a long video.

I like how you gave timings for those of us who know! I'm an aeronautical engineer so was nice to get a prompt to skip the first few bits :)

Expander cycle?!

I just now noticed his eye colors lol

best rocket video

Wasn't there a limerick about a man from Ragoon who tried to take a "methane rocket" to the moon? I keep finding one, but it talks about the guys being heard on the moon. This guy tried to fart his way to the moon.

Look into the Polywell Fusion engine. There is no reason it couldn't work. Research has been stopped.

AOC's head is exploding! Think of the Carbon Footprint of the US Government I'm a Career Pump Mechanic. Irrigation and Domestic, and to understand the Gallons per minute and PSI involved here is Crazy! To understand the "Power" involved Electrically, you would need to stand next to the Turbine in a Large Dam turning at Full Speed! But "Scientists" are Nuts! I wish I had a Fraction the money they get to "Play with"!

QUESTION: Is burn ratio the same as the stoichometric ratio in an internal combustion engine, if so does that mean that the higher the numerical value, the leaner the mixture by mass? The standard mass to compare to is air(1) so is it the same when you compare a propellant to LOX? Meaning is the reference to LOX the same as(1)? By the way a great explanation not seen anywhere of rocket science!

Can we use methane instead of gasoline in car's engine? If methane production is so simple the production can use cheap power from solar panels.

So the Raptor engine basically burns farts?....Hey! Hey! It's just a joke lol.

This is the first YouTube video longer than 20 minutes that I think I have ever watched. Great video!

all that talk about turbopumps got me thinking about what kind bearings they use. Is it normal ballbearings like a automotive turbocharger or is it some spaceage super bearing.

5:10 now you’re thinking with portals

This is an excellent video. Ten points Tim!

Wow! I learned something! :) I think in all of my meetings at work, all of my responses will be, "A methane fueled, full fuel flow stage combustion cycle engine seems like a good fit!"

Masterful work Tim!

I understood this better the more number of times I watched it

But Tim! Who will spin the pump of the smaller rocket engine that pumps the bigger rocket engine?

Dude you look like Will Wheaton's nerdy brother. Kinda sound like him too.

First video I saw on ur channel, its pretty fire. Its culmination of information that I secretly wanted to know but could not find online easily, more like this

How would any of these engines measure against the alternative / upcoming design of the aerospike engine:

Great work , bro ! You made a 50 minute video on rocket science , not only watchable but entertaining and made me wanna follow up on the other future videos you mentioned in this DOCUMENTARY !

What kind of nimrod downvotes this?

Ohh a rocket run on cow farts! AOC will love that!

Great vid. Earned my sub.

Your eyes are different colors. Did you know that?

For comparison, how about adding the Shuttle solid state boosters and the nuke engine from way back when.

Closed cycle sounds like the exhaust cannot escape! BOOM!

Seems like merlins np to me


Why does everything in America come in bunches? If you are trying to teach us science or technology try and use the correct terms please.

Lucky the Russians invented it!

I appreciate you and your patrons for making a video like this, excellent work!

Just remember, they have to make those complicated engines and make room for thrust vectoring

Crazy how good that rd180 is for its age of design

Would have to say this is a top 5 of your videos . Makes a ton of sense

An aspect of fuel properties which was not mentioned is that RP1 gells up at low temperatures. The Apollo program used RP1 in the first stage of a Saturn V rocket for the reasons of density and volume of fuel needed which were discussed. The volume of LH2 required was prohibitive to lift the entire rocket off the launch pad. Keeping RP1 from gelling up at the ambient temperatures of higher altitudes and in space precluded its use for the second and third stages. First stage separation occurred at about 200,000 feet altitude (38 miles) while second stage burnout occurred at about 115 miles altitude. Both are much higher than the service ceiling of a jet burning similar fuel. Use of LH2 forestalled problems of fuel gelling and with restarting the third stage while in orbit. Methane has properties more similar to LH2 for these design considerations.

Kerosene / RP1 can also be produced from CO2, water and energy. It is probably simpler from a chemical standpoint to produce CH4 instead of longer chain hydrocarbons but RP1 could also be produced on Mars by the Fischer-Tropsch process using the same resources as making methane.

There is no difficulty in finding hydrogen. Hydrogen is separated from methane by steam reformation. A portion of the methane is burned to provide heat to drive separation of H2 from the remainder of the methane. CO2 is produced in equal quantity to that produced if the same volume of methane is burned. Hydrogen is routinely transported over the highways in tank trucks. Some boils off and is lost during transportation if being transported as LH2. Transporting hydrogen is more difficult than transporting methane but it is a solved problem.

So the answer is: depends on what you want to do. 45:55

German Zeppelins used hydrogen as lifting gas because helium was unavailable in sufficient amount. The USA was the primary source of helium. The USA had declared helium as a critical military resource. The USA refused to sell helium to Germany. Yes, the lifting ability of hydrogen is about four times that of helium. That is not the reason hydrogen was used. Helium would have been used for safety reasons had it been available in sufficient quantity. The USS Los Angeles, a Zeppelin built in Germany for the USN in 1924, used helium for its lifting gas.

Could you talk about the cross sectional area that each takes? They talked about 30+ raptors on one super couldn’t do that with anything else but merlins

This is possible only because Mr. Musk mostly leaves SpaceX rocket scientists alone to do rocket science.

F1 on 17 flights? I count 13. Apollos 4, 6, 8 to 17 and SKylab. On Apollo 13 the centre F1 shut down 2 minutes early. I call that a fail.

what are your thoughts about syntin? Can be used similar to RP1, yet more energy, higher density.

Really Great Video... I finally understand rocket science lol

You cant really say the f1 is 100% reliable cause it only flew 17 flights. You would probably need 60 or so flights to say that

I give this video 3 thumbs up :)

I like the technical side, but you talk a little like you're trying to be cool for kids or something... that honestly won't watch this anyway. Just talk clearly and don't let any attempted hipsterness get in the way. Great Channel BTW!

Well done!!!

+Gibacke F1 only powered the Saturn V first stage, nothing to do with Apollo 13 service module explosion. The F1 was a RP1 fueled engine while the J2 engines of the 2nd and 3rd stages were hydrogen fueled. The hydrogen fueled engine on the Command/Service module was simply called the SPS (Service module Propulsion System).

im now watching you for a year.. here and then... but that video made me subscribe you :D for me it is actually a thing to subscribe to someone

+Gibacke what failed was the engine of the payload. If a Falcon 9 puts a satellite in its correct orbit and the satellite fails in itself, that's not a Falcon 9 failure.

+Emmanuel Mahuni What Tim said from 5:52 to 6:04 is not very clear to me. :( He might be talking about the Electron rocket but it coulde also be about ion-engines (I thought to recognize 'Xenon'), but it was clear he'd be clarifying himself later. And I have patience. About: "...the Raptor engine uses this additional mass to provide extra thrust" The potential energy carrying medium that I was referring to were the chemicals, not the tanks that encapsulate these. By 'dumping' the combustion products from the preburners/gasgenerators that drived the turbines into the combustionchambers, the closed fuel cycle engines have extra mass to push against to push themselves forward i.e. provide thrust. As for the energy-density I was thinking about, it was energy by mass and/or energy by volume. In a vague memory of a video from Rocket Lab they said that they could electrically drive the pumps because the Electron need only carry a cubesat to an orbit of maximal 500 km high.

Why didn’t they just use flex tape

+Apollorion ok. Thanks for the name correction. However, as I said, I really don't know how the Electron rocket works, but go to 5:52 to 6:04, Tim briefly says something about the Electron Rocket, to my understanding the Electron has a electric motor pump fed engine, meaning the motor simply pumps the needed fuel etc into the combustion chamber. I don't know why people are thinking that I am saying the Electron is propelled by a battery

+Emmanuel MahuniI get the impression that what you're referring to is the *Electron* rocket produced by *Rocket Lab* and propulsed by the *Rutherford* engine? Well, I think the reason is that the ambitions of the Raptor engine is much bigger than those of the Rutherford and that the energy density of a battery is much lower than that of a rocket fuel. Also, once the medium that carried that potential energy that drived the pumps has been used, the Raptor engine uses this as additional mass to provide extra thrust thereby dumping it almost directly, whereas the Rutherford waits to dump that extra now useless mass until the staging at which the Electron rocket dumps a/the relevant batterypack.

Awesome video man

Great video Tim helps us total newbies get some grasp on what's pushing things into space without just comparing the size of a rocket.

Sorry, are we still just igniting fuel? oh the steps forward to come....

If you think full flow is confusing, try describing and drawing the Sabre cycle in detail 3 days after being taught about it for over half your exam......

So dreamer, do you think this one will make it into the great vacuum ? Prove it to yourself first.

Drives me crazy how we're not talking about magnetic vacuum rail launches that could conceivably drop cost per lb below UPS rates.

I thought the big point of chamber pressure was to have higher sea level ISP.

Hi, Thanks a lot for super informative very popular - so, it's populated even dwon to my level - video introduction to rocket engineering. As a profane, I'll bet all-in absolutely crazy idea: why not treat methan as an - not catalyzer, not emulsitator, I don't know how it can be named - briefler: mix methan with hydrogen at stage 1, then mix mixture with oxygen at stage 2. I don't know about efficiency, but real Big Bang guarantied.

What more?Third purpose it is to be sand-like shield protection against meteorites, what forth. Aha, and four purpose is to be capasitor insulator slicing Van Allen radiation rings around earth. And then, 4R sound a bit non-harmonically. Our purposes are like bees, need to be harmonised. So, let R be B. Here we have 4B.

Twin reactor? Queen reactor? Sorry, guys, I really can't hear. Three Reactor, aha. So, let it be 3R.

Ok, due to it dual purpose let's name it accordingly: The Snow-Baba.

space x and space in general is for the dumbed down mind controlled stupid slaves that have zero discernment and zero common sense just a bunch of gullible brainwashed fools that believe all the lies that are fed to them,, space x LOL grow up would you,,

You just received my subscription good sir, amazing video. I'll hit that bell icon as well

Defiantly great info, Thanks, a lot more informative than my visit to NASA, Iv linked you if thats Ok, as my info is very basic!

Too bad space as we are told doesn't exist. Cool video though.

Going to space on cow farts!

Want cheap methane and save the farmers? According to AOC, cows should be a good bet! :-)

"for hours until your heads feel like they're going to explode." Uh... About 60 seconds. It's a fairly simple system.

Fakex - churning out mediocre cgi and successfully fooling a bunch of feeble-minded, gullible, Dunning-Kruger-esque 'scientism' fanboy zealots into thinking jewlon musk is _actually_ sending things to 'space'

F-1 engine center cutoff early on Apollo-13, made it past TLI before the explosion in the SM made the mission famously fail.

For me, the excellence of your channel is that you simplify the conversation to everyday language so we can relax and think about the ideas so engaging to us, without dumbing it down to where it is pointless fluff. That and you are entertaining while doing it :-)

Wait until you notice this guy has 2 different colored eyes, you can’t unsee it.

Yup... sorry

So this was a fantastic video and I loved it. I have no doubts that it took so much work to make this video. I could not fathom

if Musk and Bezos wanted to conquer space they'd team up, by not they sew doubt to their true intent... doit :P

old tech. ftw

Another video of the guy that just likes to see and hear himself talk

"...That's like 3km below the surface of the ocean, I can't even fathom....." I see what you did there.

Thank you for the great video!!! Question about the ability to make fuel on Mars... What about the oxidizer? Is the plan to travel with extra to compensate? Just as an aside, it seems Space X is looking beyond Mars with this plan--maybe aiming at some if those oh so methane rich moons further out

i just realized, do you have different colored eyes?

Great video, but some of your claims about the F1 are a little off; 1) During the Moon Race of the 60's, the US took a quick look at the closed cycle, and abandoned it because they thought it was too complicated to use IN WINNING THE MOON RACE, THE WHOLE OBJECT OF THE EXERCISE. The US chose simplicity where possible, and to take the NECESSARY decision to tackle combustion instability, so permitting construction of a very large main engine (the F1), thus reducing the number of first-stage engines required, thereby increasing the reliability of the eventual booster - the Saturn V. This judgement proved to be exactly correct as the F1's open cycle was (obviously) good enough TO WIN THE MOON RACE, and was fielded in early 1969 in an operational form, and its simplicity contributed to the 100% success rate of the Saturn program. It was the Russians who erred in pursuing the closed cycle during the Moon Race era. The long, difficult development alone almost assured they would lose the Race, all the more after they looked at the combustion instability problem and pronounced in insoluble. So when the Russian closed-cycle engine was finally fielded in an operational form, it was so small, in could never be a part of a reliable manned lunar booster system, since such a large number of such engines (30) would be required. Thus the Russians, with their belated, small, closed-cycle engine, tried until well into the 1970's to launch a Saturn-class booster and never came anywhere near success, failing 4 times to even attain first -stage separation. 2) The F-1 WAS reuseable, but this capability was never used. Test articles had accumulated as many as 8,000 seconds of firing time (consider that a Saturn V's total first-stage burn last about 2:45, or ~165 sec, including burn time before lift-off), requiring only minimal refurbishment, such as occaisional replacement of carbon-carbon throat....

Rocket science, I feel smart

Fantastic video! I know it's not a liftoff engine, but how do the Saturn V J2 engines used on the 2nd and 3rd stages compare?

I'm having trouble with this video... there is only a "one thumbs up" button. Mashing it multiple times doesn't do any more than "one thumbs up." :(

It's funny how people believe in the climate change/global warming/ the sky is falling fairytale, and yet, the same people are cheering for methane powered rocket engines launching high in the sky all the time. And for what? What's so great about "space" programs? Pick one or the other! Quit being a hypocrite! Do you wanna tax people for their "carbon footprint" or do you want to launch rockets over the ocean? Pick one extremely stupid waste of time and effort, because you can't have both.

Didn't one of the F1 engines on Apollo 13 shut down early, thus it's reliability would be < 100%?

u can say whatever u want bt Russians haave best rocket engines, all off rest are half copies off Russians enginens...Becese USA put some solutions ftom russians in their engines

No such thing as Boca Chica, Texas. This SpaceX facility is in my home town of Brownsville, Texas located near Boca Chica Beach.

Boca Chica village is indeed its own township... and it’s on Boca Chica beach... seems like splitting hairs to me

why are people building rocket engines in the 21st century? i thought the future was to use ground based lasers to push a spacecraft into orbit. if you don't have to take propellant with you, the costs are much cheaper.

10:00 stroke intensifies

Excelent lesson/video/diagramas. Congratulation. Severino P. Carollo Filho.

very informative. thx

We're going to mars baby!

didnt understand a damned word you said but i loved every minute haha.

great video but i feel like it could of been more in depth

Will spacex sent a ship to Mars in july 2020 -- the next launch window .?

Please demonstrate every model you mention because I wanted to be an astronaut till life smacked me in da face

Great video. I still think we gave up on Orion too early. There would have been a way to make it safe for use and the ability to launch truly heavy payloads would have been worth it. I did like the incorporation of the refuel on mars idea that came from Zubrin et al albeit with a different fuel. That guy is a personal hero of mine. Thanks for a superb primer on rocket engines. Luv and Peace.

1:11 I want a gif of this

Tim , simply excellent video. RS25 reusability is somewhat overstated as refurbishment between Shuttle flights was very costly; turbines showed serious signs of wear when stripped down. It would have been interesting to see an open cycle methane engine design along the lines of the Merlin architecture. Just taking advantage of the higher theoretical ISP of methane would have yielded significant performance gains for comparatively little development cost. However now the Raptor is on its way I wish it every success.

I made cheese toast today.

for interplanetary use, if hydrogen was the preferred choice had not been its low boiling point, once in the space could be deployed a gold film, like a curtain that would go around 6 inches (or more because of the solar wind) from Hydrogen tank, to prevent the infrared ray from heating the tank, like the space web telescope, because in the shade in the space it is 2.7 Kelvin degree and for the section of the tank of oxidizer one could use this same curtain but with perforation (if necessary). to prevent it from frozen solid.

Amazing work!!! Thanks

The title is idiotic. I therefore expected more idiocy in the video. Nevertheless, I persisted. I made it as far as holy grail and decided life is too short.

Great explanation of rocket engine types as well as design and application considerations. I actually learned something today. Keep it up!

Great video so far (I’ve got to the 6 engine comparison). Have you considered taking a look at the British Gamma engine? It appeared as a Gamma-8, and a Gamma-2 vacuum engine - in the Black Arrow satellite launcher in the early 1970s.

wow, nice music! = )

Really appreciate your efforts to make something absorbing to common people the techs developed till date... Keep it up.

It doesn’t feel like 50 minutes. I did not see the time pass and did not feel bored any second. But I’m now wondering about Indian and Chinese (and kiwi) engines. Where do they fit in there? Maybe a dedicated video for those?

Ok, I am going to ask probably a really stupid question.... Why can't turbo pumps be driven using electric motors? Is it a power output issue or? They would not need special heat resistant alloys for the blades...

It can but you will need big batteries (like the electron from rocket lab)

Super travail mec.

Добра робота!

PERFECT explanatnion!!

why wast 49 mins of ur life listening to some muppet flapping on, its simple who the king is regardless of these fuel efficient rockets of today - POWER RULES........ SPACEX RAPTOR = 500,000 LBS OF THRUST SATURN V F-1 ENGINE = 1,500,000 LBS OF THRUST

Well for me thrust by footprint rules, the highet the bigger rocket you can build.

Tomorrow is my propulsion examination... and I deemed fit to watch this 45 min long video instead of studying! So much more informative! Keep at it, Tim! :) :)

sure is a lot of praise for something that has not flown yet


am i the only one who noticed that his eyes look different colors from each other?

Amazing, dude. Very impressed with your smooth, clean delivery. Even I have a good understanding of where the technology is and what is coming, soon. Better, yet is the understanding of why and how SpaceX is making it all happen, so quickly. I think it's more clear, to me now, how NASA used dollars and cents to get the thrust necessary, instead of brain power and sense. It wasn't out of their pockets...

Congratulations. Very informative, very well explained, very enthusiastic, very passionate, very compelling.

Watched your channel grow over the last couple of years Tim. This (so far) is your highlight presentation. I thought I knew a lot about space and rockets, but every one of your shows I watch teaches me something new and exciting. I'm approaching 70, but I hope the +600,000 views so far are being watched by the youngsters. We need them to be inspired to participate in technology & science. This channel is a critical catalyst in that effort. Thanks for all you do here.

But did Space X use gold/titanium alloy to take care of the icing problem?

did you get that part when your jet pushes against nothing to gain momentum? That part stinks to the high "heavens", not even mentioning the whole brain enema, which this video is.

I think the Proton rocket engine was closed cycle and older than the NK-15. Also I believe the Block-L engine on their planetary rockets (the Molniya) was closed cycle and even earlier than Proton.

I know nothing about combustion, or anything in this topic, but why would they use these fuels over nuclear energy? Can it create enough thrust? Or it's too volatile? Or the engine would be too big?

Ok, this is a must see IF you have any hope of not becoming a Dork!

I like how you present yourself in a clear and easily understandable way. Good job!

This video was such an education for me about rocket engines in general. Then add in the coolest ones I know about, plus two in development, plus going deep into one... Just so awesome. Thank for doing this, Tim!

Hey Tim... I'm pretty sure that they had at least one F1 shutdown in flight on an Apollo moon mission (Apollo 13?), no? So much for 100% reliability of the F1?

That was a J-2 that shut down. F-1 was 100%

Russia miltary mach 3 +,usa hundreds behind,double that this decade,russia hypersonic= plasma tech,usa no hypersonic = blot,know thy enemy liars discgrace to national security + tech(period)

space x,hell no,real men dominate power not corrupt overhyped new gen facists (period)

Bravo. Rocket science is easy.

The conclusion is an honest and defensible conclusion. The Raptor engine is well suited to do what it is designed to do.

Have you watched the Apollo 11 documentery yet? It was stunning. Well recommend a watch using not seen footage of the mission.

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