Rocket Fuel Injectors - Things Kerbal Space Program Doesn't Teach

Rocket Propellent Injectors are critical parts of the engine design, they take the propellents and mix them so that they can quickly burn in the combustion chamber. Injectors can make or (literally) break a rocket design, and over the years we've seen rocket engines move from injector plate designs to more efficient options as engineers have come to understand what works well.
Thanks to Copenhagen Suborbitals for sharing some video of their injectors being tested, I hope get get to see some more flights with these:
copenhagensuborbitals.com/

[@SupremeRuleroftheWorld]

this all sounded a lot like rocket science.

[@Noone-jn3jp]

But i came for the shower science

[@miscbits6399]

Rocket science is straightforward (and mostly newtonian), This is rocket ENGINEERING

[@1320crusier]

combustion science B)

[@TheExoplanetsChannel]

True

[@jworldwide904]

This is rocket surgery. Rocket science is kindergarten in comparison.

[@crxstalline_]

THIS SERIES IS BACK!!!

[@TheExoplanetsChannel]

Yes!

[@Aceb_k]

I really needed this video but I couldent get a legal one for my rocket engine.

[@fridaycaliforniaa236]

Yes !!

[@heaslyben]

The Death Star used an impinging 8-tuplet (later 9-tuplet) like super-laser injector.

[@CarlosAM1]

Now that I think about it... maybe in a small enough rocket engine that could work. 4 for fuel, 4 oxidizer, center for ignitor? Idk.

[@miscbits6399]

@@CarlosAM1 "Our rocket nozzle is big enough to wipe out planets" ?

[@CarlosAM1]

@@miscbits6399 with enough fuel anything is possible

[@zoltanposfai3451]

Yes, but the rebels found the main combustion chamber at the centre, plus small exhaust holes drilled at the wrong angle.

[@hughezzell10000]

Well, in the end, we saw where that got them..... instability!

[@api9mm]

The 18 injector pot system in the German V2 (A4) combustion chamber was based on the successes they had with the smaller A3, which used a single pot at the head of the chamber. Due to the speed in which they needed to produce the much larger engine as a functional prototype for the war effort, they simply multiplied a system that previously worked,18X. It should be noted that during the development of the A4 starting in 1940, Deputy Director of the Peenemünde Army Research Center, Dr. Walter Thiel, had simultaneously developed a conventional flat injector plate variant of the A4 combustion chamber. Due to instability issues, it was not entirely ready for production. Regardless, in late Dec 1942, Hitler ordered full-scale production, which resulted in the V2 (A4) as we see it today with it's luminous LOX plumbing to the 18 pot system, with over 5000 having been produced that way. Much to the protest of Dr. Thiel, it was really a production prototype. Thiel's single LOX feed, to flat plate design, would have looked more like the A6 Redstone engine developed a decade later through the influence of von Braun's team in the US. Why so long? Thiel and his entire family were incinerated by an RAF bomb in a slit trench in front of his home in Aug 43. Incidentally, a moon crater is named after him on the dark side of the moon.

[@Anvilshock]

There is no dark side of the moon, at least not permanently.

[@api9mm]

@@Anvilshock Lol. I was waiting for that.

[@antoniomaglione4101]

When we are off-duty, we speak of dark side of the Moon. On-duty, writing science papers we say far side of the Moon. "Dark side" impinges on the imagination and is more artistic, ask to the Pink Floyd what they think. "Dark side" is a very acceptable artistic licence for a scientist, I believe.

[@hkr667]

Points to api for pointing out that rocket science, especially back then, was limited by time and budget. Giving unlimited resources, one could only fantasize where humans would be now.

[@daveborinski3021]

Anvilshock you are referencing the wrong definition of dark. Anvilshock’s usage refers to this definition; 4a : not clear to the understanding b : not known or explored because of remoteness. The better challenge would be; if it’s unexplored, how did they know of the crater in the first place? 🤓

[@CopenhagenSuborbitals]

Thanks for the feature, Scott! Glad to contribute to your video, great work! 🚀

[@OrionAerospace]

nice to see you guys here as well ;)

[@CopenhagenSuborbitals]

@@OrionAerospace Thanks!

[@vishalk4647]

Seems like great minds are gathering here.

[@jayriley1162]

Hey guys, there used to be an urban myth that on your first launch that part of your launch vehicle hardware was a hairdryer to defrost propellant lines. Is there any truth to this or is it BS guys?

[@jnygaarddk]

@@jayriley1162 Almost true. Not the lines, but the LOX valve itself. And this was the reason for the scrub in 2010. The hairdryer ran out of power as I recall...

[@rowdyyates3801]

I've got pintle injectors on all my garden hoses. I use them to throttle the water and even shut it off.

[@Rose_Harmonic]

I use an improvised pintle mechanism called my thumb.

[@theredstonehive]

@@Rose_Harmonic Yes!

[@CharlesP2009]

And this allows you to restart the hose, yes?

[@DistracticusPrime]

@@CharlesP2009 Instructions unclear. Yard on fire.

[@_tyrannus]

@@DistracticusPrime Instructions unclear. Yard on a lunar injection trajectory.

[@pentagramprime1585]

Today I learned the difference between "Rocket Science" and "Rocket Engineering."

[@vancelanger7749]

more generally, engineering is just the application of knowledge gained through science!

[@benbaselet2026]

@@vancelanger7749 And Eloneering is just doing something scientists said cant be done.

[@simongeard4824]

@@vancelanger7749 Engineering is where the theory of science meets the cold hard facts of reality. We don't actually have spherical cows, just the regular kind, and they're not very cooperative.

[@Lectrikfro]

Sometimes you just need a rocket surgeon

[@SolarWebsite]

Science is studying the world as it is today, engineering is building the world of tomorrow.

[@1senhart]

Now I want to buy a fuel injector and use it as my showerhead

[@Brixxter]

Hell yeah I want a pintle injector showerhead

[@Diggnuts]

Finally, proper temperature control!

[@russdill]

@@Brixxter providing super fine control over the mixing of hot and cold water :)

[@zapfanzapfan]

Buy a scrap one from an old jet engine.

[@Brixxter]

@@russdill water is for noobs, real men use hypergolic substances

[@olliea6052]

That saturn-V slo mo launch never gets old. What a beast!

[@miscbits6399]

Mike Oldfield's "space movie" dedicated about 8 minutes to it... :) gorgeous

[@StringerNews1]

Except it's not slo-mo! That's how slowly it really rose.

[@bennylofgren3208]

StringerNews1 Nah, that is slow motion alright. The Saturn V starts rising pretty slowly, but it only took about ten seconds to clear the tower (which is 100+ meters up), so it isn’t _that_ slow.

[@StringerNews1]

@@bennylofgren3208 It's called acceleration, and that's why the rocket is _not_ going full speed the moment it leaves the pad. Did you see it clear the tower in that clip?

[@bennylofgren3208]

StringerNews1 Why don’t you look at the clip again? It runs from 5:05 to 5:30, that is 25 seconds. In that time, the Saturn lifts perhaps five meters. Now, in light of this, would you like to reconsider your previous statement?

[@theCodyReeder]

Yes! I’ve been awaiting this one!

[@DFPercush]

Ready to go to Mars yet? :p

[@_tyrannus]

Your last video is right after this one on my playlist. :) We have the same taste in videos, I see your comments everywhere I go (not on French language content obviously).

[@niccatipay]

Coby have you found enough Uranium to refuel the rover or is Elon the one bringing it? Love your content mate!

[@CursedSouthwest]

Oh... you like space?

[@androbolaareospace9602]

Why does cody have only 312 likes on this comment

[@97wito]

I've watched you since the early days of high school, now I'm about to graduate in Aerospace Engineering from the Polytechnic of Milan. It's amazing to reflect on how I went from being inspired and hypnotised by your knowledge, to actually being able to understand rocket engine design. Thank you for inspiring me! Fly safe !

[@martianz.3996]

I'm literally using these to supplement studying for my rocket engines exam right now.

[@EricCosner]

I’ll never look at shower heads 🚿 the same way again.

[@OverlordZephyros]

Now they look more sexy 😏

[@russc788]

My shower head will feel woefully inefficient

[@TheExoplanetsChannel]

Oh

[@zoria2718]

"What if my shower is an awfully inefficient combustion chamber on someone's rocket?"

[@dale62676]

My shower head uses dihydrogen monoxide as a propellant.

[@Pow3llMorgan]

I'm so happy you included footage from Copenhagen Suborbitals' tests!

[@CopenhagenSuborbitals]

Agreed!

[@Matt_10203]

@@CopenhagenSuborbitals huh would you look who it is!

[@Ultrawup]

Imagine the level of nerd swag one can achieve by having a rocket fuel injector as a showerhead... "Hey babe, my shower has coaxial swirl injectors, wanna come over and try them out?"

[@niccatipay]

Instant moist

[@malcolmmellon8692]

Please report if this works

[@niccatipay]

Reporting! Rocket fuel injector works as intended. Entire bathroom is now oven.

[@MultiChuckleberry]

Elon Musk is on record as asking one of his first dates if she was interested in electric cars. It did not go too well. I suspect that - as a conversation piece - telling a date that you have a rocket-injector as a shower-head would have a similar effect. Elon says that recently the "are you interested in electric cars" approach has become more effective. I wonder if being a multi-billionaire has anything to do with the change? Perhaps all you have to do to get your rocket-injector-shower-head working effectively as a bird-pulling line, is to compliment it with becoming a multi-billionaire. Best of luck to you my son and more strength to your elbow. The rest of your life is still in front of you :-) Pleeease let us know how you get on.

[@BrilliantDesignOnline]

It works great, but you only get the girls with thick glasses and you spend the whole time evaluating the shower swirl injector engineering.

[@driverslqqk7940]

Real good Scott. Your pictures you showed was familar to me. I was Chief Inspector at Wellman Dynamics Corporation from 78 to 1988. We built the main fuel injector for Rocketdyne for all the Space Shuttles and the Martin Marietta fuel transfer elbow on all the 7 space shuttles back in 1980 thru, 1987. We used aluminum and had the secret McCanna cores made from glass for the fuel passages to a tolerance of +/- .0015. We have a perfect record on all class 1A castings, never have had a part fail from the wide range of Boeing ALCM Cruise missles tanks, warhead and tail engine section. Sikorsky main gear box housings for Blackhawks and conopy frames for the General Dynamics F-16 Vipers. The turbofans for a wide range of Pratt & Whitney jet engines. among many other parts in alum & mag. I really enjoy the knowledge you have in the videos you make.

[@HuesonWong]

Literally my dissertation that I'm working on right here (on swirl coaxial injectors): While I can't be 100% certain, the Raptor engines' ones would probably be similar to the Copenhagen Suborbital's ones in that the fuel is swirled by entering the injector tangentially (consider the location of the fuel rich preburner and turbine with respect to the injector face plate), given the location of the oxidiser rich preburner and turbine, the oxidiser should flow more or less in a vertical straight line towards the injector. As the oxidiser is entering the injector coaxially, it cannot be swirled like the fuel, although that does not mean it cannot be swirled (here's the guessing bit) - I reckon the raptors probably pass the oxidiser through swirl vanes to increase or create swirl. The reasons for this are: increased shear between fuel and oxidiser creates more intense Kelvin Helmholtz instability which kind of results in folding of the fluid layers more efficient combustion; a vortex breakdown can act as a bluff body for the fuel to impinge against; the vortex breakdown acts as a recirculation area for more thorough, and complete combustion; the recirculation area serves to stabilise combustion; the swirl vanes themselves produce a pressure drop, meaning that the injector can be shorter for the same amount of pressure drop; shorter injectors mean lighter engines; shorter ones are stiffer and are less prone to fatigue and cracking which is key to reusability. the only drawback I can come up with is that they're a bit awkward to make.

[@prdoyle]

I understand all the individual words you used...

[@HuesonWong]

@@sasor098 Thanks! always wanted an internet cookie :p

[@claudiusdunclius2045]

And that “awkward to make” is where 3D printing comes in!

[@A.Lifecraft]

You may be the person to know an answer to my question: Why is it, that the whole plume is not swirling? Because i got the impression that instabilities or fluctuations are better contained in rotating streams of liquids or gases. Also they could work nicely with that centrifugal pressure gradient, as they could overexpand the plume without "stalling" the nozzle. Creating a vacuole in the middle of the plume, one might be able to create an aerospike-effect and make the engine more adaptive to changing ambient pressures. So am i missing out on something?

[@thomas.02]

Kelvin Helmholtz instability a.k.a. mushroom clouds :D in all seriousness though thank you so much for the in depth explanation, i hope you'll design rockets of your own one day (or better, bona fide spaceships built, used and maintained in space)

[@emanueledimatteo4744]

Missed this series

[@TheExoplanetsChannel]

Me too

[@JimMeeker]

Mach diamonds make me smile.

[@williamgreene4834]

The mach diamonds are actually the parts of exhaust stream that drops to subsonic velocities which I still don't fully understand. But they make me smile too. :)

[@superdupergrover9857]

Pure, distilled, unadulterated awesomeness. THAT is what mach diamonds are.

[@dmeemd7787]

Hell yeah, make me have a cheeky-ass smile everytime!

[@maxk4324]

@@williamgreene4834 Actually that's not correct. A jet of gas displaying mach diamonds is by definition moving at or above it's own speed of sound (some regions get down to mach 1, but never below). As soon as the gas slows to below it's own speed of sound at some distance from the exit, that is where the mach diamonds end. In reality, this point fluctuates as nothing in real life is as perfect as on paper, but it is most definitely supersonic. Mach diamonds form when the static pressure at the exit plane of a supersonic nozzle or choked orifice is lower than the ambient pressure (which is what I think you may have read and possibly remembered incorrectly?). In the case of rocket nozzles, Mach diamonds are an indication of over expansion. This means that the diverging nozzle section is larger than would be theoretically most efficient at that altitude. Of course you can't adjust the nozzle size mid flight, so most nozzles on boosters are designed to achieve perfect expansion at some altitude between liftoff and burnout. The exact optimum altitude as specific to each rocket.

[@maxk4324]

@@superdupergrover9857 I totally agree. It's just such a shame that they are actually an indication of a rocket engine operating inefficiently.

[@alis4328]

North Korean rocket scientists: "Write That Down, Write That Down!"

[@hameedullahjasat2560]

I am pretty sure some government officials watch his videos ... Especially north Korea

[@benbaselet2026]

I don't think they are in the business of developing new advanced injectors. Just copying the working russian ones is the way to spread awareness of the great leader to the world.

[@icollectstories5702]

Scott uses mostly published data which the North Koreans, et alii, certainly have copies. It is possible they have unpublished data that Scott does not. They certainly have more experience in building rocket hardware than most of us. Scott isn't magical; he just does the work we are too lazy to do ourselves. But don't believe a foreign country is as lazy.

[@hameedullahjasat2560]

@@icollectstories5702 ofcourse ofcourse ...just sum exaggeration on my part

[@Blox117]

@@icollectstories5702 i think everyone knows that, the joke is that north korea is incompetent yet desperately wants to build its own successful rockets

[@gustavgnoettgen]

3:22 Scott: "Blah blah blah" Me: "combined mustard and ketchup dispenser for hotdogs"

[@agoatmannameddesire8856]

Need an app to identify the hotdog first.

[@dmeemd7787]

😂😂😭😂

[@RCAvhstape]

I don't know if they still sell it, but you used to be able to get peanut butter and jelly in one squeeze bottle. It wasn't very good though.

[@gustavgnoettgen]

@@RCAvhstape I'll try that with a toothpaste tube 🤔

[@samrobinson9110]

@@RCAvhstape Perhaps a coaxial swirl nozzle would have improved the PB x J distribution efficiency?

[@StYxXx]

lol, USA: "Stop! Don't show our engines, they're protected by ITAR! Delete that photo!" Europe (ESA, Copenhagen Suborbitals): "LOOK AT OUR INJECTORS! LOOOOOOOK AT ALL THOSE DETAILS!" :D

[@rtrThanos]

The space race began out of fear of another country being able to drop ordinance from space. We can’t help it that Europe is full of Care Bears who think that sharing is caring, Tenderheart.

[@theophrastusbombastus8019]

I mean, Copenhagen Suborbitals is a crowd funded company, they post al their progress to be accountable to their investors. Also I don't know of ESA being particularly more open with their designs.

[@harkonen1000000]

CopSub doesn't actually share exact details of their injectors either. Though they developed them from resources available online.

[@hkr667]

@@rtrThanos TRIGGERED

[@miscbits6399]

Yup and ITARs are an absolute pain in the proverbial if you happen to WORK in the EU space arena because some stuff is open and some stuff has snowflake americans getting triggered if the wrong people look at it.

[@maxk4324]

3:55 That's actually a best case scenario of impinging jet misalignment. Depending on the impinging pattern used, if one of them misses it's mark you could be shooting a jet of pure oxidizer straight at the blazing hot wall, which regardless of the material used likely wouldn't be long for this world.

[@ShiftyMcGoggles]

I believe that's called an unplanned rapid disassembly.

[@joansparky4439]

@@ShiftyMcGoggles shorthand is RUD, not URD ;-)

[@maxk4324]

​@@ShiftyMcGoggles For the rest of the rocket, usually yes. But for the unlucky engine it's more like the combustion chamber drops the "chamber" and simply becomes combustion as the metal of the walls is rapidly burned away from the flow of pure oxygen (or equivalent oxidizer).

[@jimmahon3417]

Back in my Rocketdyne days, we used to refer to that condition as "hardware-rich burning". An oxygen-rich emergency shutdown of an SSME from mainstage operation (say, due to a failure of the high pressure fuel turbopump) could SLAG the entire interior of a powerhead assembly in a few seconds. The results were extremely ugly, and very sobering to behold.

[@OrionAerospace]

YESSS keep this series alive we love it so much!!!

[@AirCommandRockets]

Rocket science is easy, Rocket engineering is hard.

[@midship_nc]

Center of mass, check. Center of thrust, check. Fuel, check. Point it down range and watch it go when the orbital mechanic guy says to. Then do some simple math, and it comes back. Maybe. Finite element analysis, check. Material sciences, check. Chemistry, check. Thermodynamics, check. Fluid dynamics, check. Rotational equipment reliability, check. Best welder in the world, check. Supplier of exotic metals, check. Giant assembly building, check. Turbomachinery, check. Electronics guy, check. Largest forge press in world, check. Tens of thousands of man hours in development, check. Test stand, check. Extreme lead times on vendor supplied parts, check. And so on and so on...... lol

[@spvillano]

Rocket science is easy. Build a bomb, have it controllably explode in only one direction, add steering, have it explode in that direction for as long as one needs to, avoid RUD. ;) Oh and schedule failures for national holidays...

[@miscbits6399]

@@midship_nc or you could build a Sea Dragon in 8mm submarine steel in a shipyard, pressurise via 4 tons of liquid nitrogen and light the blue touchpaper? It used to be joked that anyone brave enough to do it would either completely destroy the aerospace industry as it currently exists, or make a very spectacular fireworks show and end up bankrupt. Mind you, if SpaceX can afford to demonstrate a Falcon heavy, they can probably afford to lose a Sea Dragon.

[@midship_nc]

@@spvillano lol RUD....the BSOD of space travel.

[@midship_nc]

@@miscbits6399 you will have to excuse me but what is submarine steel? Some kind of seawater resistent stainless like 2205? Ive heard of certain grades of stainless that do okay in seawater, I dont have any naval DOD customers here in NC but if i did, i would go Ti at the minimum for seawater duty. Although, there are a couple oil rigs in the pamlico sound that would be my accounts technically.....just dont have a helicopter at the moment lol.

[@torybruno7952]

Nicely done Scott. One other consideration for injector design is the influence it has on the Rapid Combustion Zone. This is the region just downstream of the mix zone that is also the primary source of energy that feeds acoustic combustion instability. This is the type of instability that arises from a high frequency acoustic resonance within the combustion chamber, also known as "screech". Screech can destroy a combustion chamber from mechanical environments, pressure oscillations, and rapid heating in as little as a few seconds. Baffles, which you also alluded to, are sometimes added to interfere with the radial and tangential standing acoustic waves.

[@Wingman77tws]

“Rocket science has to work within rocket engineering”. My favorite part of this video.. haha. So true

[@hellishgrin4604]

Damn... I was just thinking to myself "you know what would be a good idea" and 10 seconds later, pintle injector... Guess i'll never have my million dollar idea if I go into the rocketry business, too many people smarter than I.

[@revenevan11]

Lol, I've always blamed that sorta thing on time travelers stealing my intellectual property! In a hypothetical alternate future where you or I have come up with the idea and made our millions, some criminal time travelers copy down the idea and take it back in time to before we've developed it... and beat us to the market! I swear they sometimes even wait until after I've thought of an idea but then they come out with it before I can ever start prototyping 😉 One of these days I'll make it to a good timeline!

[@ericmelton4630]

HellishGrin460 don't give up

@@revenevan11 lmao

[@SternLX]

The pintle injector has been in use for longer than rocket engines have been around. They were designed for Diesel engines first. It doesn't surprise me that Rocket Engineers borrowed some Internal combustion engine designs to solve some of their design issues.

[@DistracticusPrime]

Consider it affirmation. Given similar inspirations, you had the same idea, and it's a successful one. Hopefully your next idea beats the rush!

[@mannymartinez3751]

I was at rocketdyne in 1963 and we tested our injectors at Edward's AFB. We had a jig called a solid wall .

[@Chef_PC]

I really miss your KSP plays.

[@theundead1600]

KSP 2 is coming 🤞

[@ThatBillmanGuy]

Wait... KSP 2? Oh boy. Is this by the new developer that kicked out everyone else? Or the original guys making a new game? I need to look this up..

[@finefondue9307]

Billman Warren new devs with the old ones, look at the trailer it has interstellar travel tons of new engines not just combustion metallic hydrogen base building wheels that don’t suck etc

[@gadnuk7159]

As a mechanical engineer I didn’t know I wanted to be a rocket engineer until now... wow that whole video was incapsulating. Thank you

[@LPFR52]

As an engineering student looking to build a liquid fuelled engine for a capstone project, this was amazing

[@alexanderl8794]

I grew up in a time, not much older than this one, where I was obsessed with rockets. I wanted to create my own, from scratch, and looked to the internet to try to find information about it. I kept digging and digging through articles and wikipedia pages I couldn't understand, asking a NASA astronaut at Kennedy Space Center about sparkplugs in rocket engines, poring over images I found and drawing and redrawing them so many times they are still seared into my memory. I wish this series was around when I was a kid -- I would have loved it. But I can still watch it now, and know what I couldn't teach myself with a google search then. Thank you, Scott, for teaching another generation of children like me.

[@mjproebstle]

i like how you engage us you tubers in your deliveries, as if we were actually out here trying to build our own rockets! its a very personable and intimate approach that definitely captivates the listener. cheers!

[@Jens.Krabbe]

What do you mean "as if"? Some of us are literally out here trying to build rockets!

[@gregwarner3753]

No longer have a machine shop.

[@that_teegor]

Love these videos, and I definitely miss your Kerbal series. Hope you do some more when KSP2 gets released :)

[@gregwarner3753]

A long time ago when i was about 12yo i tried to make a liquid fuel rocket engine. First problem was, aside from gasoline, I did not have any liquid fuel. OK the gasoline could be pumped from a gas tank or from a gas tank but that was too much trouble. I also could not get any Oxygen, liquid or gas, as this thing was being made in my step father's shop and he would not pay for an oxy/acytelene set. So my fuel/oxidizer choice was propane and compressed air. The engine has a cylindrical combustion chamber with the air injected from the head of the chamber and the propane injected into the center of the chamber through a tube with radial holes. The entire thing was machined on an antique belt driven lathe from a piece of scrap steel. It took several after school days to get this built. I tested it by clamping it in a vice on an outside work bench. I had enough sense to not test it in the shop. Check out the MYTHBUSTERS test of their hybrid rocket in their shop. The test procedure was to pump up a tank as far as possible with air and hook it to the injector plate at the end of the combustion chamber. Then plumb a propane tank to the center tube injector. Start the test by turning on the propane and lighting the gas exiting the engine with a kitchen match. Then the air was Inejected and the smokey flame retreated into the chamber. Then it made a lot of noise with a very clear flame. I was pleased with the result even if I had made a complex weed burner more than a rocket motor. The entire thing is why you should not let a curious 12yo kid alone in a machine shop.

[@pjimmbojimmbo1990]

I am pleased you mentioned the LM Descent Engine. Thank You! I knew it could be Throttled, but I never found any explanations as to how it was done. I know there were to different designs brought forth.

[@jessewilson8676]

I would like to see colored water used during the tests like yellow and blue, The visibility would be nice

[@WillArtie]

Thats exakery what I was thinking - used different colors so you can see da mixin.

[@olisk-jy9rz]

What's the point, you'd just see green water coming out. It's the whole point of the system, to mix things to infinitesimal levels. If you could see separate colors coming out, well that's one shitty injector.

[@lawfulmasses]

Love all your videos, Scott! Hope you and yours are safe and healthy!

[@akshyapani]

Mr. Scott I cannot thank you enough for spreading free education and making it seem so easy. I was more intrested in the pintle type nozzle which you have mentioned very briefly in this video, there aren't many like you out there. Thank you again.

[@benhongh]

I did a preliminary injector study for a pre-mixed NOX/alcohol project back in uni. After spending a whole term coming up with a pair impingement design, the workshop mechanics had a look at the design, shook his head, and said "nope, too hard to drill". A massive embarrassement but also a valuable lesson for me.

[@deterstruble]

Some people have a shower head as a fuel injector Scott Manley is the kind of guy to have a fuel injector as a shower head

[@TwoFingeredMamma]

Lizards don't take showers.

[@Metal73Mike]

That's been some time, glad to see you going back to the roots :-) Thanx !

[@qmoonwalker3847]

Amazing summary Scott. FYI - splash plate was used in Rocketdyne's J2 GG. I was told it was the Achilles heal of the J2 and one of the most difficult combustion devices components to perfect. They tested many many configurations via cut-test-fail to eliminate burn thru of the GG combustion chamber. The solution was a choke ring which was added just downstream of the combustion region. Looking forward to checking out more of your videos!

[@Roestikrokette]

Hello, its Patrick from switzerland here :D today i just want to thank you for your work! its nice to see how the people are exited about space again. and its because human like you! thanks a lot!

[@alexg3446]

Finally! Copenhagen Suborbitals gets a well-deserved shoutout! All space-lovers should stick together.

[@cory96777]

Been excited for this video! Had a feeling it was coming. :)

[@NavidIsANoob]

This series is actually insane and I hope you realize how good this video is, Scott.

[@frogman740]

I've been looking for an intuitive representation of the pintle injector for hours, should of known to start by looking on this channel. Thanks Scott !!!

[@georgekanulas9037]

I never knew that rocket fuel injectors might be that interesting! Thank you for another excellent video. Waiting for the one about the meteor rocket 😉😉👉👉

[@CopenhagenSuborbitals]

They're the heart of the engine. ;)

[@vishalk4647]

And one of most complicated part of it.

[@CopenhagenSuborbitals]

@@vishalk4647 Yes.

[@vishalk4647]

@@CopenhagenSuborbitals oh by the way waiting for new videos of yours. Love to see your birdies fly!

[@CopenhagenSuborbitals]

@@vishalk4647 Tank you! They are coming. :)

[@cavegoblin101]

You where so cheerful at the beginning! It put a smile on my face.

[@fiveoneecho]

I love these videos because even if you don't cover EVERYTHING (as if that was possible), you somehow manage to cover the bits that I have been trying to learn about for a while with no success.

[@remsmith3233]

Thank you Scott. Manley for your time and effort explaining rocket fuel injectors. My eight grade grandson and I enjoyed and appreciate your explanations. You are truly a valued person communicating all sorts of space related issues regarding the opportunities offered by space.

[@joelswanson7826]

When I saw the video title, I thought it was an old video because he hasn’t done a video in this series for a long time!

[@Fryguy101]

Combustion instability is a recurring issue with big rocket engines, so I'm curious your thoughts on the Sea Dragon and its proposed single massive first stage engine (Calculated to be 350MN, compared with the Rocketdyne F1's piddly 6.7MN). I think combustion instability would've killed it even if they had decided to take the Sea Dragon seriously, but do you think such a large single combustion chambered engine is even possible?

[@Tarototh]

Such an esoteric yet fascinating topic and explained SO WELL! The clear, simple animations you used really illuminated all the differences. You are a Master Expert Explainer and videos like this are why you are one of my favourite science channels. Keep doing this forever please.

[@beholdpeople7554]

This is exactly what I needed from the beginning I was confused about how does fuel distribution system works !!! But now I’m crystal clear thanks for your information

[@maxwilson7001]

0:51 “Good propellant injectors can make all the difference between your engine performing excellently, and it exploding due to combustion instability” So one part goes wrong and the whole thing blows up. Isn’t that just normal rocket science?

[@TheBackyardChemist]

eh, more or less

[@extrastuff9463]

Based on what I read in Ignition by John D. Clark that happened a lot in the early days. Some people even took their entire labs down with the experiments. I wonder at times how hard investigations into aborted launches are (and were), these days there are probably a lot of sensor logs on the ground. But the actual pieces of the rocket that make it to the ground will be quite mangled if found at all.

[@Ron4885]

This is the kind of thing I love learning.

[@clark1066]

I've been waiting for another one of these episodes for a while. I don't really know where to get information like this so I love seeing it here. Not that I put much effort finding the information but I love it.

[@sjoerdhuls4899]

I’m so happy! I’ve been hoping you’d do a video on injectors. I’m enjoying it thoroughly! Thanx!

[@debapratim3976]

I missed this series sooo much!

[@PaulPaulPaulson]

This offers a great background for rewatching some of copsubs videos!

[@CopenhagenSuborbitals]

Good choice!

[@Nuovoswiss]

Glad you made a video about this. This is one thing that DIY science youtubers consistently miss when trying to build their own liquid propellant rockets.

[@ahaveland]

Superb! Your hard work on solving the animations really paid off!

[@urban6613]

I have been waiting for this video so long

[@StreuB1]

Unlike split triplets is the way to go; we've been using them for over 20 years. Its a simple design which places the manifolds in relatively easy machine and design locations and gives outstanding performance. Added advantage is its easier to balance out the resultant momentum of the impingement sheets as well as making the injection orifices relatively the same size for the more common LOX/hydrocarbon propellant combinations. This helps with hydraulic losses and makes your pressure drop across the fuel and oxidizer similar if not equal. Really smooths out the injection stream pattern. Edit....although there are some interesting versions of the pintle injector as well.....currently designing one now; err for the past year that is. lol Interesting meaning specialized variations.

[@fotmheki]

I didn't know anything about fuel injectors so I love it! Hopes there are more to come.

[@anthonyhusiak]

Scott, one of your best videos to date! Please keep the rocket engineering videos coming!

[@samspade8612]

Good tutorial. Very interesting, would've like to have seen more destruction of course.

[@Aman4457_]

Hello there the series is back yaaay

[@AKAKiddo]

It's people like you Scott, using youtube, where I have learned so much about all the various types of rocket engines. I truly never knew how complicated they were, and how they operate with such extremes in both pressure and temperature. It's amazing to me that they work as reliably as they do.

[@foxpup]

This is why I subscribe. Scott is not afraid to get down and dirty with the technical details of these machines. :-) ..learned some new stuff today because of him :-)

[@hobbified]

3:22 I found your problem - you're trying to run the rocket on ketchup and mustard instead of RP1 and LOX.

[@absalomdraconis]

Yeah, needs an oxidizer, maybe something FOOFy.

[@dukenukem8381]

thru Cheddar cheese injector

[@profwaldone]

Me at 0:00: probebly looks like a snow machine. Me at 17:51: a very, very fancy snow machine.

[@gmupps]

I manage a diesel fuel injection shop. Something I'm often explaining to my customers is the importance of good atomization. The smaller the droplets, the more surface area available to react with the charge air, and the more efficient the combustion. Thanks for sharing, this was fascinating.

[@SUPERHEAVYBOOSTER]

Your videos are always my favorite part of my Mondays!

[@Yuuni_Shiroza]

Yes!. nother "Why Kraken isn't real" Episode

[@roidroid]

Why do we even have the word "bedroom", when we already had the perfectly servicable phrase *"thrust chamber"*

[@andersjjensen]

I'm sorry innocent one.. but "the thrust chamber" is something else entirely. Yes, it is often located in the bedroom.. but it is not the bedroom itself :P

[@dmeemd7787]

Yeah "thrust chamber" could be any room, huh? 😂😂

[@marcusapperley6456]

It's no room... It's a space station...

[@roidroid]

I tried telling her that injectors sometimes just don't work & the science behind it isn't well understood. So far this particular baffle technique has worked.

[@bullwinkle5445]

@@roidroid you need the swirl method

[@jeromec7367]

Such a fascinating topic and great video! I loved it! I would love to understand more in detail the causes and the solutions to combustion instabilities but I imagine that it gets very technical

[@michael_mouse]

... having the fuel/oxidiser mixing process explained in simple and concise terms for us 'non-rocket scientists', is very much appreciated ... excellent video Scott, thank you!

[@galfisk]

What are the considerations for injectors in hybrid rocket engines? I imagine not having the oxidizer gouging divots in the fuel might be important, but how critical is the design?

[@mduckernz]

It's gonna differ hugely depending on the fuel grain geometry. If it's a simple cylinder then having the oxidiser behave as though the whole fuel grain is a swirl chamber would seem to be about optimal. A ring shaped injector with vanes to angle it should work well... or a large cylindrical pit with angled injection to swirl it, with the diameter of this pit matching that of the fuel grain.

[@rustyspace900]

As Matt D said, swirling oxidizer is the key to an efficient burn with Hybrids. I attended a lecture by a man from Nammo (Norwegian weapons manufacturer at the Andoya Space Centre) he said they use a swirling injector in their rockets, kinda like a rifle barrel, to get the twirl.

[@CarlosAM1]

Id say something like a metal garden hose front to spray the oxidizer into the fuel :D

[@gregwarner3753]

When the Mythbusters made their hybrid "civil war rocket" I think they simply used the end of the pipe that delivered the Nitros Oxide oxidizer. I do not believe they ever considered inducing swirl to the flow. Find the episodes where they test the rocket inside their shop, near disaster, and acdually flew the rocket. FWIW - they made the thing in three days using schedule 80 steel pipe.

[@hardwareful]

every time: Hello it's God Manley here

[@comment2009]

Nice use of the fluid dynamics animations. Each timeI see the that clip from the hypergolic safety film, I chuckle at the manor the tech is jumping back and forth. The film still holds up today in teaching the importance of treating hypergolics with the utmost care.

[@bobbym3155]

Great video. Really interesting stuff. Loved the garden hose nozzle.

[@moosemaimer]

I watched a video once about engineering mistakes that featured somebody from NASA... he was using a new probe tester to check an injector plate (which took a very long time to make, and almost as long to check) and he input the wrong command on the stick, which sent the probe right through the plate, breaking both of them. That particular axis was reversed on the controls from the machine they had been using previously, which is like somebody handing you the controller and having to play a game with the Y-axis inverted from how you play it.

[@heinrichwonders8861]

Once again I realize: Space is hard.

[@miscbits6399]

Space is hard - and painful if you step outside Getting to space is harder - and even more painful if you get it wrong(*) Staying in space is harder still - if you don't circularise your orbit(**) Life support is even harder than all that. (*) RUDs (**) The primary difference between a sounding rocket and a ballistic rocket is where it finishes its journey... :)

[@simongeard4824]

@@miscbits6399 And always check your staging... ;)

[@replicantmonk4310]

0:04 I love that model of the MC75 Profundity you have there, sir!

[@antoniomaglione4101]

Thank you Mr. Manley for the compendium. One thing I would like to add about combustion instability, which has to be considered in all injector designs. A difference of few mulecules of oxygen on one side or another of the location of combustion is enough to bend the flame to one side or another. In given level on energy, the singular combustion nucleuses at each mixing location (of fuel and oxydiser) starts to "talk" each other, in a quest for that little more oxygen, starting a positive feedback that create an energetic rotating vortex that can destroys the chamber. It wasn't fully understood 50 years ago, but the buffers of the Rocketdyne F1 avoided that all jets in the chamber talking to each other, creating ten separate virtual combustion Chambers. Nowadays this is fully thermofluidodynamically modeled with computer software, so it no longer considered an hard to crack problem.

[@epincion]

Fascinating comment thanks

[@filanfyretracker]

rocket fuel injection sounds a bit like cars, An endless fight to get the optimal mix of fuel and the "air"(in the case of rockets oxidizer)

[@NeutronSplitter]

*Destin enters the chat* Me: "Sorry Destin, no laminar flow here" *Destin leaves the chat*

[@movax20h]

Probably the best video on this channel ever. Cool and amazing engineering.

[@Malfunct1onM1ke]

That was a very informative and interesting video. I would like to see more of these, eapecially on the concepts of staging.

[@stekra3159]

Next Turbopumps

[@jnygaarddk]

UUUHhhh. The holy grail...... yes please. You'd be surprised how much power is involved in those... The RS-25 aka SSME is rocking some 71.000 HP on the High press Fuel pump. Only 23.000 on the HP LOX pump. Mind blowing when you look at the size of it...

[@HiroNguy]

@@jnygaarddk Yeah, and John Force's Top Fuel engines are up to 11000 hp. How cute! 😀😀😀😀😀 Rocket science FTW!

[@outofturn1920]

someone ask the question, how much power would it take to correct the earth orbit to be a more convenient length of time like 365 days.

[@Azivegu]

149.545.000km

[@Kineth1]

I can't help thinking that adjusting the rotation would require less energy than adjusting the orbit.

[@zockertwins]

A lot

[@lobsterbark]

@@Kineth1 Would depend on how much leverage you could get.

[@outofturn1920]

@@Kineth1 we could slow the earth by orbiting a large mass, we might need two to prevent wobbling, but that way we can get rid of that whole leap year thing.

[@waynebinks1091]

Thanks Mr. Manley for such an excellent presentation. I am certainly not a rocket scientist, but your video makes sense to me and I have a greater understanding of the complexity and scope of what it takes to make it to space! Keep up the good work for us dummies by explaining it so we can understand!

[@tinkmarshino]

well I always knew it was complicated but never knew any of the particulars about the injectors beyond the bare basics.. so thanks a lot for not only explaining but showing me the various kinds and how they work... This was extremely interesting..

[@tdscwhelan]

A friend and I are having a debate. Would it be called: a) rocket *motor* b) rocket *engine?*

[@suntzuwu]

Motors run on electricity, engines run on combustion. ...

[@tdscwhelan]

@@suntzuwu we were confused, as Google defined "motor" as "a machine, especially one powered by electricity or internal combustion, that supplies motive power for a vehicle or for another device with moving parts."

[@donjones4719]

Both are in widespread use for liquid propellants, and the base definitions/derivations of motor and engine fit. For solid rocket boosters I see motor used much more than engine.

[@ChrisCooper312]

Both fit. A motor is something that causes motion. Rocket motors definitely cause motion. An engine basically converts something into something else. Rocket engines convert chemical energy to kinetic energy.

[@paultrappiel9943]

Motor is short for motivator; a device which causes movement. Engine is more specific and seems to imply conversion of energy to perform work; chemical, thermal or kinetic.

[@SpecialEDy]

I prefer carbureted engines...

[@oliversmith9200]

'And a gas pedal on the floor of the capsule.

[@Shadow77999]

@@oliversmith9200 lol

[@rossracing6433]

Amen brother. Incidentally, I wonder what the 1/4 mile times of various rockets would be.

[@patrickthebutcher]

the 19th century called... they want their tech back.

[@jeanoulie69]

8 years of Ksp but never heard about those critical pieces in rockets!! Thank's dude!

[@Dappdude]

I thought I knew a lot about rockets, but I learned so much from this! Great video!