Defying Atmosphere - How Rocket Engines Get Tested In A Vacuum Before Going To Space

[@elephantwalkersmith1533]

I helped design the J6 test stand, which held a vacuum on one shuttle solid rocket engine through its entire operation. We built the largest concrete vacuum chamber in the world. The facility looked like a giant banjo. We ran the HP boilers for three days to accumulate enough steam to run the 20 toroidal steam injectors. Lots of fun!

[@shanemeyer9224]

Man I would absolutely love to just have a conversation with you, I’ve been so lucky to meet some of the most amazing folks in the space field in my career, I got to meet and talk with the doc who monitored the Apollo astronauts on the way to the moon and back as well as many other and it’s just so amazing learning from them. They have just incredible stories

[@tbrowniscool]

Please tell us more!

[@SpecialEDy]

That's incredibly exciting! The rocket gets all of the glamor, but it designing, building, transporting, assembling, and testing all of the parts that is the real feat of engineering.

[@vbscript2]

J6 at AEDC? Nice! I remember touring that when I was doing a summer internship there during college. Pretty impressive test cell.

[@cowabunga2597]

You work with JPL ?

[@wgoulding]

It's a truly surreal moment to see something I designed show up in a Scott Manley video!!! I work on the Mars Ascent Vehicle first stage solid rocket motor, and I've been watching Scott since I was in high school. His videos were a non-insignificant part of why I went into aerospace engineering.

[@soranuareane]

This is the true measure of fame. You've made it in life. It's all downhill from here.

[@wgoulding]

@@soranuareane Dude, what's crazy is that I was thinking the exact same thing. It's like my life purpose has been fulfilled.

[@ManBearPigCreative]

What an awsome project to be involved in, i know i speak for many when i say i cant wait to see the fruits of your labour!

[@thedarkknight1971]

OK, if you worked in/on/around that particular field... MAYBE, you might have an idea on this... I wonder if NASA has ever heard of the term "KEEP IT SIMPLE, STUPID..." ie, the Mars sample return mission, WHY THE HELL ADD COMPLICATIONS to a system like have the sample return rocket effectively 'Yeeted' into the air to then fire up and fly away??? MULTIPLE FAILURE POINTS ADDED! Just have a simple launch rack/gantry move or angle over to have the rocket pointed up/or at specific angle, and then the rocket can launch from there (as per the normal way of launching rockets 😏)... I REALLY DON'T UNDERSTAND why they would ADD MORE RISKY procedures to something SO VERY COSTLY, and SO BLOODY COMPLICATED to retrieve something so BLOODY VALUABLE (in BOTH financial cost AND scientific value) from a planet +/- 225 Million Km away!!! IT DEFIES LOGIC!!! 🤔😒 😎🇬🇧

[@guessedUK]

⁠​⁠@@thedarkknight1971 any gantry or rack represents additional payload for the outgoing mission to deliver to Mars, which would either reduce the remaining (useful) payload or require a bigger rocket. I would think they considered that possibility and rejected it.

[@vodostar9134]

As a teenager (circa 1975), I toured a NASA facility where my father was working for the summer. On the tour, I saw an electric rocket being tested in a vacuum chamber. (That was mind-blowing at the time lol). I always assumed all rockets were tested that way. Very interesting to see how they actually address all these engineering problems I hadn't considered.

[@PrinceAlhorian]

When the shuttle engine starts, the first few seconds with with flow seperation, you can actually see the nozzle bells flex until the thrust pressure stabilized.

[@ericlotze7724]

1:03

[@Gnefitisis]

Yeah I never noticed that until Scott pointed it out.

[@pillow1427]

There's also videos of early tests of the SSME at the SSC A-2 test stand where you can see the diffuser; there are also other tests where the smaller 35:1 expansion ratio nozzle was used and it definitely looks cursed

[@RCAvhstape]

That slow motion video of the nozzles flexing is kind of terrifying, the amount of energy being released by that beast is awesome. I love the RS-25 engine.

[@Tunkkis]

I had wondered what that was for a whole while before learning about overexpansion.

[@Scott-.]

Shout out to Cody's Lab! Love his enthusiasm for science.

[@blob537]

Love Cody's Lab! Shame YT hoses him so badly but happy to support him other ways.

[@user-bw6jg4ej2m]

@@blob537 what does YT do to him and why?

[@blob537]

@@user-bw6jg4ej2m they haven't been paying him for years and it's been a nightmare for him to sort out. It's a shame because he puts a lot of work in and produces great stuff. As far as why, your guess is as good as mine.

[@temhgb]

@@user-bw6jg4ej2mhe’s basically shadow-banned. I don’t think he’s been on anyone’s recommended in years, only gets views by people searching him basically

[@Wulthrin]

@@user-bw6jg4ej2m they wont pay him. reasons unclear

[@adjoran4789]

Just want to say I absolutely love these in depth explanations of systems and methods. This channel is one of the gold standards for STEM fields on youtube.

[@lytalo]

Very interesting. I worked at White Sands Test Facility back the late 70s. We had several vacuum chambers with vacuum pumps for short tests and a huge steam injector for much longer runs. It was originally built for Apollo, but was used for SLBM, the shuttle reaction control system and other engines. I got to watch a few of the steam injector runs, it was very exciting.

[@oasntet]

Thanks! I'd always wondered how they maintained a vacuum with a burning rocket, ever since Cody's Lab video. I'd assumed it was some trick involving huge tanks of vacuum, maybe with falling water in place of pumps to try to keep up, but this is so much cooler.

[@GnanaPrakash86AP]

Wow that's a relatively simple way to do it, but would be very difficult to test large rockets for more than short periods.

[@MrJdsenior]

It would have to be HIGHLY accelerated to high velocity water, wouldn't it, before startup, unless it was a VERY large pipe? Kind of like a gas piston on the rarification side, the type that occurs in car exhaust headers, which is the reason the length of the individuals to the collector matters, tuning for a given RPM? Is that what you are envisioning? Either that, or I'm misunderstanding your concept. These things are not hair dryers, there is a LOT of flow there, at VERY high velocity.

[@oasntet]

@@MrJdsenior Like, take a swimming-pool-sized tank of water where the entire bottom can be opened. Obviously it wouldn't be able to pull a full vacuum thanks to the air pressure outside and the tendency to boil at low pressure, and it'd only last for a second or three, but maybe something other than water would improve that a bit. Maybe still helpful for testing the few seconds after ignition to see how long it takes to become stable? Of course, it's all impractical in light of the Venturi-like use of the rocket to provide its own vacuum, which is really ingenious and probably way cheaper to build and run.

[@paradiselost9946]

@@oasntet even if it were an infinitely long pipe... sorry, "pool"... it wouldnt fall away any faster than G, and the pulling of a vacuum just slows it down... will only retain the pressure thats sort of equilibrium to the rate of descent and the gas filling the "void". you can play around with the old "inverted cup full of water" and hanging weights off the sheet... find its always surface area that counts. you can only suspend as much weight as the atmospheric pressure over area can manage versus the vapor pressure of the water over area. its not moving until it falls... do it with a piston and the piston height will always be proportional to the weight as the volume of vapor in the space above increases... whereas the bernoulli effect, venturi... its characteristic is that high velocity fluid has ZERO pressure at right angles. and obviously any angle steeper that creates the desired separation of the fluid with resultant "void". as long as what comes AFTER the nozzle can deal with the flow, and just like a wing... isnt so poorly shaped it enters turbulent flow, aka "stall".. people overlook that what comes AFTER a venturi tube is even more important than the intake! the intake sort of naturally does its own thing as air stagnates and "smooths" sharp corners... whereas in the tail, the flow is contrary to the change in pressure... remember... flow always likes to go from high to low... not low to high! the lead out of a venturi tube has to be very gradual and smooth to work properly. steam water feed injectors are a pet love. exhaust steam water injectors are even more amazing... using the heat left in the condensing steam to still get water into the boiler whilst under a pressure far exceeding the exhaust steam used... amazing, when you dig through the old books, how clear it all is... the whole converging diverging nozzle ideas... or turbines... consider a water sprinkler that spins... everyone thinks the water will squirt harder from the nozzles as the centrifugal force will fling the water out and create a higher pressure at the nozzles... this indeed is what happens! except... its counteracted by the fact that fluid from the hub to the nozzle would rather flow from a high pressure to a low pressure... and by restricting the flow of the water in the arms with the nozzle to create more squirt, the pressure had to rise and of course, the differential in pressure causing the water to flow DOWN the arm is reduced... exactly in proportion as the pressure is increased and creates more force on the nozzle/arm. net gain? zero. the arms spin with the force produced by the pressure applied by the source, no more, and often far less! lol. most people have a real hard time with forgetting that most systems are not isolated...

[@zephyrandboreas]

Fascinating. In documentaries you see the facilities but never know in reality what most of the things actually do or why they are organized in a specific way. This is a brilliant episode for someone like me who likes to know how equiment used to make other things or have specific uses is itself designed and built.

[@HiddenWindshield]

Fun fact: In the 1920's, when Professor Robert Goddard first published a paper suggesting that rockets could be used for exploring space, none other than _The New York Times_ published an article making fun of him because they thought that rockets needed an atmosphere to "push against". It took another 50 years, until the day after the Apollo 11 launch, for them to publish a retraction.

[@glennpearson9348]

And the complete irony here is that the rocket equation was first developed in 1897 by a Russian scientist, Konstantin Tsiolkovsky. It only took New York Times journalists 53 years to rediscover what the rocket world knew half a century earlier.

[@clayel1]

wow, i thought this was bs, but it’s entirely correct!

[@georgegeorge-es2lh]

No, that flexing is deliberate. The computer is testing the engine's gimballing performance under thrust.

[@zephyrandboreas]

Took them that long??😂

[@rdizzy1]

Conspiracy theorists still spout this nonsense nowadays.

[@richardbelcher4773]

I work at Aerojet Rocketdyne in Redmond Washington. I test rocket engines in vacuum chambers everyday. Mechanical pumps and cryogenic pumps as well as steam ejectors. Thanks for the video

[@tihzho]

That is what a lot of people do not know is rocket exhaust at sea level is at atmospheric pressure. That's why as soon as the rocket gets some altitude it can be seen that the exhaust flares out quite a lot! 5:02 What you have is similar to a vacuum diffusion pump which are kinetic transfer pumps. They operate with a fore pump producing a vacuum in which silicon oil is just at boiling temp. This supersonic stream of vapor transfers its kinetic energy to gas molecules present directing them towards the vacuum pump (providing the working vacuum) where they are removed from the chamber. I used to service vacuum pump and systems.

[@williamhoward7121]

Finally a subject that was not rehashed! I had no idea that any of these test facilities existed wonderful video Scott!

[@warlockcommandcenter]

Scott I worked art the Air Force Rocket. Propulsion Lab Edwards AFB now called AFRL saw test done in altitude chambers and outside in the world. It was fun and loud. Saw massive steam vacuum systems and the chambers they sucked down. We worked on a few solid motors that were for KHIT AND AHIT using beryllium as opposed the the normal Aluminum. The long delays from building the facilities to doing the testing I have some great stories that you would love.

[@KevinSmith-ys3mh]

OMG... the exhaust from a beryllium metal powder solid rocket would be incredibly toxic, and for much longer than most hypergolics! I certainly hope the steam/water injector system captured most of the particulates, or that area would become a Superfund contamination site and anyone downwind likely poisoned! I used to work with beryllium oxide and metal alloy components- (carefully) as there were always bio-hazard warnings and special cleanup requirements associated with use😮. I'll have to revisit my e-copy of "Ignition!", but it seems unlikely that the ISP boost would be worth the risks, at least within earths atmosphere.

[@warlockcommandcenter]

@@KevinSmith-ys3mh I know that they had a few areas that had beryllium contamination and were exclusion areas, the vacuum chamber was planned to be sacrificed for the series of tests for the satellite killer system under the Star Wars programs I know that Khit and Ahit were proven technology and the last piece of the puzzle and I think that was also finished. I was exposed the hyperbolic propellants they are nasty got sick twice with full protection. Got to love it.

[@stuartgray5877]

@@KevinSmith-ys3mh I work at a Major Aerospace company, and we flat out REFUSE to machine any Beryllium. We use it but must have outside vendors work with it. It is just too toxic.

[@rayoflight62]

Hello Mr. Manley, This video is a great explanation of the rocket engine vacuum test facilities. I appreciate all the efforts you put in this type of videos; this is of great help in learning more and more of all engineering subtleties of rocket engine design. Greetings from the UK, Anthony

[@SimonAmazingClarke]

Because these people can't work it out in their head, they assumed it is impossible without doing any research. Great video Scott

[@beefgoat80]

Thanks for the video. It’s on of those things that make you scratch your head until it’s explained to you. Then there’s the “oh, that makes sense” moment. 😂

[@shanemeyer9224]

This is exactly the video I’ve been begging to have made!!! I have always wanted to know more about how they vaccum test engines and now I finally do understand some of it, thank you Scott

[@sarahgoo5541]

Thanks Scott, that was really interesting. It’s an aspect of rocket engineering that I was completely unaware of

[@peterkallend5012]

Those people who say rocket engines can't work in vacuum clearly demonstrate the Dunning-Kruger effect. 😂

[@rayjd1650]

I was lucky enough to get a tour of NASA Armstrong Test Facility a few weeks ago and got to go into the vacuum chambers. The setup they use in the ISP chamber is surprisingly simple. Since hydrolox engines like the RL-10 (which is what it was designed for) run hydrogen rich, they have to safely deal with all that excess hydrogen in the exhaust. All they do is spray water into the exhaust to condense the steam, then have some pipes with expansion tanks to continue to separate the water and hydrogen, then at the end are flare stacks to burn off the hydrogen that is left over.

[@rayjd1650]

Also, your explanation about differential heating in the chamber is spot on. They have lights and heat lamps to add heat on one side, and can even roughly simulate day-night cycles in Earth orbit.

[@epincion]

Thanks Scott. Very interesting. Those layered giant steam venturi pumps must be awesome in operation.

[@olegfedorov3225]

Ignition in vacuum also bothered Sergey Korolev. It was one of the reasons he come up with R-7 design where longer central stage2 ignites together with stage1 boosters.

[@crcpeart]

Blows my mind how much goes into developing a successful rocket, let alone a reusable one within 20 years 🤯🤯🤯🤯 Great video as always Scott 👏👏

[@77Patriot]

Excellent explanation Scott. Great video

[@TomHill-xh7ec]

I worked at the Edwards Air Force Base Rocket Lab in the early 90s. Lots of these sorts of test cells out there. The XLR-132 was tested at altitude while I was there, and I also got to see the first Titan IV SRMU explode on the test stand. Thanks for the trip down memory lane!

[@KevinSmith-ys3mh]

Whooah- a Titan booster explosion would be a hell'a big sparkler display, have you searched out any online video of that event? I do recall some video of a test which resulted in disqualification of manned capsules with solid boosters- perhaps one of Scott's on the constellation program (Aries 1?), and of course we've all seen the Space Shuttle "very bad thing"😢.

[@MattyB_84]

Just heard a rocket engine hot fire test from Redstone arsenal in Huntsville. I live about 20 miles away and my house was shacking. Love the video and your explanation! Great to understand a little better what they are doing when I hear these tests.

[@stuartgray5877]

But according to SOME of these morons (like papalegba, 77thbridagesockpuppet, and DrCash77) rockets engines DONT accelerate the exhaust gas and they DONT perform any "Work"! SO HOW can they make noise that can be heard from MILES AWAY?

[@PSRAM-ge6ww]

This morning I was thinking about how engineers test their rocket engines in vacuum and in the evening (IST) you posted this video😮. I am very surprised and also 😊.

[@thomasgunther]

I wondered the same when I watched the video of the MSR rocket being tested in a vacuum yesterday. Then I thought, maybe Scott Manley will explain this. And now I have proof that he is mindreading.

[@johannesgutsmiedl366]

I actually recently got to visit the P4.2 test stand in Lampoldshausen (shown at 8:03) which was used in development testing for the Ariane 6 Vinci upper stage engine... it can in fact do all the things Scott mentions like having cooled walls to better simulate the thermal radiation behaviour etc, in fact they cna simulate the entire mission profile for a typical Ariane 6 second stage flight. From a technical perspective it's super impressive (especially because the videos and pictures don't really get across just how HUGE those facilities are), but I couldn't help thinking that you could easily get 90% of all that data by simply, ya know, actually flying the thing once...

[@mariodistefano2973]

Hi Scott, this time learned definitely something NEW!!! I could never imagine how they did these tests and now I'm grateful to you for all these explanations! Thanks!

[@ghost307]

Thanks for another excellent video. I always wondered why SpaceX didn't send a raptor as payload on one of their Falcon rockets just to try starting and running it outside the atmosphere.

[@linecraftman3907]

It would experience ridiculous acceleration and most likely fall apart at such high acceleration

[@davidquirk8097]

Fascinating. I spend a lot of my time devising testing strategies for power systems and to hear that Rocket Engineers have similar headaches is very interesting.

[@AlphaPhoenixChannel]

That's fascinating! It's like a UHV oil diff pump on the most ridiculous of steroids... rough-pumping with a water venturi would not have been my first guess for high-expansion testing - although to be fair I can't think of very many guesses... I would have probably said a few enormous turbines or something. I wonder if that was a materials science limit back in the day, or if the steam venturi is actually more efficient. it's certainly dead simple and hard to kill!

[@axelBr1]

Steam ejectors are way more efficient, and can pull nearly a total vacuum and have no moving parts. Vacuum pumps are some sort of positive displacement device, so very low flow capacities. Centrifugal or axial flow compressors (turbines use a high pressure gas) would have sealing difficulties around the blades, and would go into stall to easily, (too little flow for the speed).

[@gtbriggs6614]

Can honestly say I learned something great today, thanks Scott

[@sirjohniv]

You make a really big Hoover and hope for the best.

[@tanmaysingh267]

😅😂😂

[@alexdhall]

I'm pretty sure that's part of the plot of Spaceballs....😹🤣

[@HiddenWindshield]

@@alexdhall Just make sure that the hero keeps his shwartz away from the test. 🤣

[@gijbuis]

Thnx Scott for this brilliantly researched presentation of how rocket engines are tested - so much stuff that really makes sense when you think about the challenges of firing up and burning gases in space!

[@mikefochtman7164]

As a kid, we used an 'eductor' which is similar to an air ejector, to remove water from our small boat. A garden hose with a water supply, this funky-looking brass tee fitting, and another short section of hose from the fitting that led over the side. Just turn on the garden hose and watch the water get 'sucked' out. And don't forget the old steam locomotive 'boiler injector'. Now there's a clever bit. Take steam from the boiler at a pressure of say, 100 psi. Run it into this clever casting that also has a connection to the water tank in the tender. It sucks water out of the tender, and via a third connection on the casting, pushes water into that same 100 psi boiler!!! At first it almost sounds like perpetual motion, but it works great!

[@jeromethiel4323]

Naval vessels use eductors too. And for the same reason. They are great for de-watering a space that was either flooded to to a leak, or flooded due to firefighting. What makes an eductor better than a pump, is that they can carry debris which would foul a pump.

[@mpetersen6]

​@@jeromethiel4323 There are similiar systems that are used to evacuate contaminated air from enclosed workspaces. Basically centuries that bleed compressed air through a slot at the wide end of the venturi. The better ones will move 100 cm for every cm introduced at operating pressure (typically around 6.5 Bar). Operate on the Conada Effect. Another product that uses the same effect is a Dyson fan.

[@TheEvilmooseofdoom]

@@jeromethiel4323 That's where I had the idea explained to me, on water pumps.. I think it was on one of the big WWII US battleships.

[@jeromethiel4323]

@@TheEvilmooseofdoom Steam power plants use the same technology to evacuate air from condensers. It's usually called an ejector in such systems, but it's the same principle of operation. In an ideal world, no air would get into such systems, but it always does. So you use a little low pressure steam to continually draw extra vacuum on the condenser to ensure peak turbine efficiency.

[@StYxXx]

Sounds like a water-jet pump found in schools. We used those in labs (chemistry) - just plug them to the faucet and let the water do its miracle

[@blob537]

I had been wondering how this was done! Excellent, Scott!

[@capnrotbart]

Those test chambers are really big suckers for rocket engines. I‘ll see myself out now.

[@jeromethiel4323]

I see what you did there! ^-^

[@laflemme7247]

Just watched a video of yours from nearly a decade ago about KSP. Very happy to see that you're still making content! Your explanations about aerodynamics are brilliant.

[@danielbarreiro8228]

Old steam locomotives used the same principle of steam injection to help combustion. The exhaust of the cylinders was sent to nozzles pointing upwards at the base of the chimney, and that would push the fumes upwards creating a vacuum along the boiler that would suck the fumes and head from the firebox at the back. Most of the 'smoke' you see coming out of a steam locomotive when it is running at full speed is actually steam, not so when it starts, when there's a lot of smoke and not enough steam to suck air into the firebox so the combustion is far from optimal.

[@danielbarreiro8228]

BTW, there is this classic footage of the engines of the Saturn V lighting its engines while still on the pad. First the smoke comes out randomly, as if in a explosion, but soon enough, the flow of gases settles into the exhaust trench and all those gases are sucked into the trench as if a huge vacuum cleaner has been turned on, a great visual example of the effect you describe in the video above.

[@gregalbert4033]

Mr. Manley! I just learned more than I ever thought that I could about this subject in mere minutes, and I owe it all to you, sir!! Thank you very much, and keep up the great work! 👍

[@ralphlorenz4260]

The "Mars Wind Tunnel" facility at NASA Ames is a rather tall building, was originally built as a high-altitude test chamber for the Agena rocket, I think. It was a bit of a pain to do experiments in, you had to wait until the steam plant across the road charged up to do 'paid for' work in an arcjet chamber (mostly for heat shield testing). Only then could we piggyback on that to pump down the chamber to do our Mars experiments... still, a unique facility.

[@kingdomdom1]

Not often I learn much on spaceflight but this was a whole new chapter!

[@soranuareane]

Would you be willing to do a video about these "super-fast actuators" that either open or close in brief fractions of a second? I can think of a few ways to do it (spring-release, seal perforation...) but I'd love to see how people like NASA or JPL do it.

[@VinokDesign]

In the petrochemical industrie we had fast acting valves in case of reactor shut down. It would prevent backflow . Those where 8 1 meter diameter pipes injecting air in the reactor. The valves could shut. In 0.2 sec. And indeed just like you said, there is this big ass spring mechanisme above the valve ready to get triggers.

[@trouty7947]

I know at least for smaller pipes you can use explosives to actuate a valve extremely quickly. Downside is you can only open or close, not both, without replacing it. But in a test stand thats fine.

[@VinokDesign]

@@trouty7947 I don't think those will get approved of in a explosion proof zone :-D (ex-zone)

[@charliebray6758]

Very cool info, Scott! Thanks for making the explanations of the engineering used in a format that an old aircraft mechanic can understand.

[@osprey413]

This is an interesting scientific and engineering reason for having a base on the Moon. You could setup engine testing facilities in the vacuum of the Moon to truly properly develop vacuum optimized engines.

[@neeosstuff7540]

Great job Scott! I'd been wondering how they did this testing. So glad you answered this!

[@jeremyglass4283]

This is a conveniently timed video as well with Starship’s 2nd IFT coming up, as one of the milestones raptor has never achieved despite years of development, is an ignition above sea level (technically ~500 m on the landing burn for the hops) it is still very much up in the air (or lack thereof I suppose, no pun intended) in regards to whether spacex will get those 6 engines running or not, it’s a completely new environment for them.

[@epincion]

I'm pretty sure that SpaceX would have tested ignition a Vacuum Raptor in a vacuum facility

[@jeremyglass4283]

nope, Elon said that would be too expensive, complicated, and would hinder mass production

[@epincion]

@@jeremyglass4283 why would testing a single V-Raptor in a vacuum chamber facility hinder mass production? It’s the design that is being tested not each engine that is subsequently made. As to the cost of testing one or a couple of engines - the facility exists already it was built decades ago in the Saturn era and then refitted for the Space Shuttle program and could be hired.

[@DrWhom]

@@epincion I would totally believe you except for that thing that happened on the last launch

[@jeremyglass4283]

@@epincion I suppose there is nothing stopping them from doing that, but spacex believes it’s not worth the upfront cost for just a couple tests at the most. Especially when they have experience with starting engines in vacuum with Merlin.

[@paulbyland]

Cody's lab is one of my favorite youtube channels.

[@ComradeCatinsink]

i love moonlanding denier’s they’re basically saying „uh, I don’t understand science, therefore it doesn’t work and everything is fake”

[@DrCash7]

just like this comment ^

[@atticmuse3749]

I was literally just wondering how vacuum engines were tested yesterday! Great video as usual!

[@gulfstudies]

It would make an interesting video to talk about the low pressure engine test stand built at Stennis Space Center. It was never used because budgets. As I understand it, the design basically used steam to make an artificial tornado into which an upper stage engine would be fired. Cost a lot of money, but NASA decided they didn't need the testing. Ultimately a dead end but I am sure it would make a good story.

[@DenizenVI]

Didn't Rocket Lab lease that stand? I have a colleague who worked on parts of that, so I was excited when I heard it might get some use.

[@JackKowalewski]

I instantly recognized the thumbnail pic, but Scott never mentioned our facility where this engine was tested and photo taken. This is at the Altitude Combustion Stand at NASA Glenna research center. ACS uses gaseous nitrogen ejectors to maintain vacuum during a test. The goal of the test program shown here was to demonstrate the capability to light a maneuvering thruster that run on sub-cooled fuel and oxidizer. methane and lox.( that's why the flame is such a pretty blue.)

[@mightylink65]

I always thought about this and I thought it wouldn't be so simple because of all the extra exhaust the rocket would add to the chamber, so there's gotta be a way to suck that out.

[@SubZero_NH3]

Wow I just assumed they couldn’t be test under realistic conditions but they found a way! Very cool video

[@djtopherau]

wow, who would have thought, even testing rocket engines is rocket science

[@coriscotupi]

05:08 - It seems like somethihing like this is happening on the engine close-up views of the Saturn V launches, as seen from the E-8 camera. The initial smoke billows up, but then gets sucked back down from the thrust generated below.

[@StevePemberton2]

The subject is a reminder that the Raptor engine that we are all so used to by now has not actually flown in space yet. Clearly SpaceX has done plenty of the type of testing that Scott discusses here, but it will be interesting to find out if they come across any differences in actual flight, considering how unique this engine is.

[@johndododoe1411]

It's not that unique, being built from the same mechanisms as a Merlin or F-1 engine, only arranged optimally for their mission .

[@FastSloth87]

@@johndododoe1411 Are you really comparing a full-flow staged-combustion engine to a gas generator? You could say it's not unique because it's similar to the Soviet RD-270 or Rocketdyne's FFSC demonstrator from the 90's, not the F-1.

[@mikeissweet]

Nice! I always wondered about this. I figured MASSIVE vacuum chambers and very short burns but the tube is a very clever solution

[@JohnDoe-tx8eu]

Scott and Cody collaboration when?

[@ninehundreddollarluxuryyac5958]

I was always curious about this ever since you mentioned different engines being tested in vacuum. I never would have guessed that this method would work.

[@BennyColyn]

Everyone knows that “Sir Isaac Newton is the deadliest son of a bitch in space.”

[@ammosophobia]

I served on a submarine, and this reminded me of something interesting. There is one 'hole' on a submarine - the circular area around the screw (propeller) shaft. It needs to pass through the pressure vessel while still being free to revolve at a high rate. We overcome this by ejecting water out the gap at a higher pressure than the ambient pressure. Just a fun fact. Also - in case of failure, we had an inflatible ring that would seal out the water. This would prevent the screw from turning, but you would then switcvh to the diesel propulsion which has a screw stowed in one of the ballast taks. If the inflatible fails ... we had 'padding' to shove in there, as it were.

[@johndododoe1411]

How would that stowed screw generate significant propulsion with the main shaft blocked?

[@KevinSmith-ys3mh]

​​@@johndododoe1411Two methods occur to me immediately: First, drop the prop outside the hull on a steerable drive shaft like an outboard or sterndrive used on sportboats- that was used sucessfully on FFG7 class frigates from the '80s. Second, (and simpler) keep the prop inside the tube-like tank and open doors at each end when needed, like bow thrusters on large ships, and forming a pumpjet drive with steering nozzle optional. Also both methods can be electric motor driven from outside the pressure hull, so no rotary shaft penetration required!😊

[@thomasgoodwin2648]

Who knew rocket science would be so expensive? 😉

[@honkabooly]

And so complicated!

[@nedcollier1495]

Hi Scott, thank you for getting back to me and taking interest in my query about the vacuum of space and combustibles, I watched Apollo 11 on tv in 1969, have been a sky viewer since then..... fly safely

[@gabrielhacecosas]

And do these terraplanners also think that a gun in a vacuum has no recoil? Or that in water they have 1000 times more recoil? 🤔

[@allineedis1mike81]

Those would be second thoughts. They don't have those.......

[@ASpaceOstrich]

Ironically before it was proven otherwise by actually achieving orbit, there was some consternation among scientists about whether a rocket engine would actually work in a vacuum. I think Scott mentioned it in a video. The idea was that with nothing to "push off" there was no action to create an equal and opposite reaction. It sounds absurd now, but at the time I guess it was a much more valid worry.

[@deonmurphy6383]

Very educational about what has to be done to replicate actual conditions, other than microgravity.

[@ThZuao]

I thought they used a venturi vaccuum nozzle to pull gas out of a big chamber, using the rocket's own gases. You know, like a paint sprayer. Turns out I was not exactly spot on, but quite close.

[@stuartgray5877]

The Tactical High Energy Laser project (THEL) DID use a very large liquid Rocket Engine (Atlas perhaps) to pull a vacuum on the liquid laser reaction chamber to pull the reactants through it quickly enough to form the laser beam. Now that we have fiber-laser amplifiers we don't need the giant chemical lasers we used to use.

[@KevinSmith-ys3mh]

​@@stuartgray5877Thats interesting, makes me think it might have been used on the 747-based airborne laser lab a few decades ago? I recall reading some article years ago mentioning chemical lasers aboard that plane, and after the latest North Korean ICBM "test/threat" over Japan- was thinking it would be useful to mess with their development program😂oops!

[@muditverma3785]

Also, on Earth, air tends to inhibit the exhaust gases from getting out of the engine. This reduces the thrust. However, in space (vacuum) since there is no atmosphere, the exhaust gases can exit much easier and faster, thus increasing the thrust. Therefore, the rocket engine actually works better in space than here on Earth. In either case, Newton's 3rd law of motion (every action has equal and opposite reaction) is in action, albeit more smoothly and efficiently in a vacuum. Thanks Scott for sharing the knowledge.

[@stuartgray5877]

Scott Manley - Well I just witnessed undeniable evidence of rocket propulsion in a vacuum with my EYES Thursday Morning. I had just finished putting the WSF-M spacecraft on top of a Falcon9 Rocket on Wednesday. I then watched that rocket (with my EYES, the Eastern Range tracking cameras, and the SpaceX video) ascend into a vacuum, Deploy the second stage which lit IN VACUUM and accelerated away. Then we observed the first stage TURN AROUND and FLY BACK to VSFB and LAND right in front of us. I LITERALLY Saw the Boost back burn and the entry burn with the naked eye. That booster went as high as 120 kilometers while using its propulsion systems. These deniers need to go watch one THEMSELVES so they can stop exhibiting the Dunning-Kruger syndrome in public.

[@papalegba6796]

Great, you should go on his show to talk about it. But that won't happen, will it, psycho?😂

[@AM-rd9pu]

@@papalegba6796Why don’t you go and talk about it?

[@papalegba6796]

@@AM-rd9pu ok waiting on my invite 😂😂😂😂😂😂😂

[@AM-rd9pu]

@@papalegba6796 Have you tried reaching out?

[@stuartgray5877]

@@papalegba6796 Why don't YOU tell us how I watched that rocket do what you claim is impossible WITH MY EYES.? What's that? You CANNOT EXPLAIN HOW I WATCHED A ROCKET PERFORM PROPULSIVE MANEUVERS IN A VACUUM - WITH MY EYES? What a surprise!

[@MCsCreations]

Thanks for all the info, Scott! 😊 But yeah, with so expensive missions you don't want last minute surprises! Anyway, stay safe there with your family! 🖖😊

[@Hykje]

People who say that rockets don't work in space usually also have a quite 2-dimensional view of planet Earth.

[@someoneyouknow79]

The good old Honorable mention on Cody’s lab

[@chuxmix65]

Rocket engines do NOT push against the launch pad. Get that out of your head!

[@papalegba6796]

Pretty sure they do, weirdo.

[@ppleberrynd]

@@papalegba6796 pretty sure they don't, cHaTbOt.

[@oberonpanopticon]

They definitely do, that’s just not what propels them.

[@papalegba6796]

@@oberonpanopticon so why am I getting abused for stating the obvious? Is w=PV not a gas law?

[@oberonpanopticon]

@@papalegba6796 I’d think that rockets would exert force on the launch pad, but that’s not what propels them. They accelerate because gas has mass and every action has an equal and opposite reaction.

[@rocketman2tm]

Thanks for covering that. I've always wondered how they tested the vacuum optimized engines.

[@rocketman484]

nice screen name

[@Forest_Fifer]

Youre talking about flerfs arent you? Its not just Newton's 3rd law they dont understand. They just dont understand. Anything.

[@Tomyironmane]

"And then they put the entire S-IVB in a cryogenic vacuum chamber for test firing" is not a thing I had expected to hear today. Maybe I should have expected it, but I didn't, and it is amazing.

[@stuartgray5877]

Scott Manley - I would ban user 'papalegba6796; from your videos. It is a troll with multiple accounts, and it has already accused you of being a pedophile in these threads below.

[@papalegba6796]

No I haven't, but seeing as you claim to be an award winning spaceship engineer why don't you go on his show? 😂

[@stuartgray5877]

@@papalegba6796 You absolutely DID! I commented on your comment when you posted it. Now stop lying, It IS what you are best at.

[@papalegba6796]

You're not an award winning spaceship engineer at all are you?🤔

[@stuartgray5877]

@@papalegba6796 Yes. Five NASA achievement awards for Mars Global Surveyor, Stardust, Genesis, Deep Impact, and Kepler Space Telescope. I am sure there are others I never actually picked up.

[@papalegba6796]

Ok so go on this guy's show then 😂

[@Draliseth]

Shout out to Cody's Lab! Love these types or videos from you.

[@MediaLieDetector]

That’s not a vacuum.

[@papalegba6796]

Correct

[@stuartgray5877]

Technically ANY pressure less than atmospheric is considered "vacuum". "vacuum" - A vacuum refers to a space where the pressure is lower than atmospheric pressure. In scientific terms, any pressure lower than the standard atmospheric pressure at sea level (which is approximately 101.3 kilopascals, or 101,325 pascals, or 1 atmosphere) is considered a vacuum. Rough Vacuum is considered anything better than 1.0 Torr. Earth's atmosphere is less than 1.0 Torr at *only 50 kilometers altitude* . You can watch any of the SpaceX videos to see that their rockets have no trouble performing propulsive maneuvers above 50 km and even as high as 120 km during a boost back burn. JUST GO WATCH THE VIDEOS and quit DISMISSING them like imbecile papalegba here. he flat out refuses to evaluate any evidence that has the potential of proving him wrong. So, he cannot even WATCH a SpaceX launch.

[@MediaLieDetector]

@@stuartgray5877 Derp.

[@stuartgray5877]

@@MediaLieDetector highly intelligent response Bless your little heart!

[@MediaLieDetector]

@@stuartgray5877 Surprised you even know what that means. 🤪

[@allancopland1768]

One of your most interesting posts to date Scott.

[@papalegba6796]

Grown man who has a room full of kids toys trying to explain science 😂😂😂😂😂

[@stuartgray5877]

I'd rather be a grown man with a room full of toys than an imbecilic high school dropout that thinks they are capable of explaining physics to actual rocket scientists...

[@papalegba6796]

That's nice for you 😂

[@stuartgray5877]

@@papalegba6796 Bless your little heart!

[@papalegba6796]

Ok ChatGPT guy 😂

[@ppleberrynd]

Adult who lives in his parents basement trying to counter fact 😂😂😂😂😂 Get a life @papalegba6796

[@mazack00]

I knew a guy who INSISTED rockets can't work in a vacuum. No matter how it was explained to him, and he was a smart guy and a great car mechanic, he refused to believe it. It was very strange.

[@Scaw]

Not strange. He was just having fun teasing his credulous friend.

[@mazack00]

@@Scaw What? Dude is super old, like actual boomer old. And they've expressed this opinion to everyone they know through their entire life.

[@seaislevel7233]

To have ANY kind of thrust inside of a vacuum is impossible. Stop being ignorant. Stop teaching children lies.

[@papalegba6796]

Thrust is an external force by definition. And a vacuum cannot apply an external force. Game over NASA.

[@jaredf6205]

Says who? You can literally try it yourself if you wanted to.

[@papalegba6796]

@@jaredf6205 no you can't 😂

[@jaredf6205]

@@papalegba6796 Buy a vacuum chamber, turn it on, put a small rocket inside and light it.

[@papalegba6796]

@@jaredf6205 repeat the Joule expansion experiment? Why, when it already proved rockets don't work in a vacuum? 😂

[@jamesmnguyen]

Scott Manley answering questions I never knew I needed to be answered.

[@edjohnson2192]

What's with the rainbow spaceship. Don't make the mistake Bud light made. I'm unsubscribing.

[@stuartgray5877]

please do. Don't let the door hit you in the ass on the way out.

[@throwawayavclubber7269]

lol

[@ferkeap]

Magnificent testing facilities, very impressive how extensive all that work has to be before you fly.

[@papalegba6796]

If Newtons third law supports rockets working in vacuum then provide a free body diagram showing the force pairs created please. Yeah you can't so you wont. Ever 😂

[@CaptainSpicard]

Wrong channel mate.

[@papalegba6796]

@@CaptainSpicard nope 😂

[@stuartgray5877]

papalegba - YOU are the one that cannot provide a force diagram since you won't even tell us "From where does the FORCE originate that accelerates the mass of the exhaust gas into the vacuum". HOW could you possibly give US a force diagram when you refuse to answer this question?

[@papalegba6796]

Nothing any NASA chatbot posts makes sense 😂

[@h.dejong2531]

This is your lucky day. Fran Blanche published a video showing exactly what you want.

[@r4pids]

Words cannot express how awesome this Vid is

[@frankgulla2335]

Scott, thanks for the explanation of testing vacuum engines on the ground.

[@Boppin.]

As always your explanations are *stellar* Scott

[@paulhaynes8045]

Blimey - I actually understood that! Excellent, Scott, thank you.

[@BarryRowlingsonBaz]

Power from condensing steam is how the first steam engines worked in the industrial revolution. Thomas Newcomen would love this video!

[@muratgurol446]

This is awesome, Scott, you're literally giving lectures!

[@old_guard2431]

Air ejectors (described as steam powered toroidal ejectors, or some such): I find it fascinating that this near anvil-level technology is mixed in with all the more advanced stuff to make this test system work. They could have literally raided the spare parts bins for the high-pressure boilers used to power the things. Once steam turbines replaced the early reciprocating engines to power ships and electrical power generators, pressure and temperature of the steam had to go up massively, bringing with it the problem of air in the boilers, which would cause serious corrosion problems for the boiler tubes. A certain amount of air is dissolved in the feed water, which is released when the water is heated and flashes to steam. Even in these closed systems a certain amount of steam escapes through seals, valve packing, etc. even if there are no significant leaks, so fresh feed water has to be added in small amounts nearly constantly to maintain boiler water levels. The air ejectors run constantly, releasing the air and condensing the steam to go back into the feed water system. Conservation of this water is important even on land-based systems because of the high level of purity required. Steam turbines on ships came into their own immediately prior to and during The Great War, so this technology is over a hundred years old.

[@wtfpwnz0red]

I love how many of my favorite science channels reference Cody's lab

[@mrman5517]

i feel like this entire video is a reminder to KSP players to enjoy those early 'test part at altitude' contracts :D

[@C40V15]

I love a good scott video with fluid dynamics and schematics of big facilities. There must be so much research work behind these videos. Thank you!👏

[@sofakingfunnyone]

Cody's lab rocks