Are Aerospikes Better Than Bell Nozzles?

Timestamps:
00:00 - Intro
06:20 - How Nozzles Work
16:00 - How Aerospikes Work
19:55 - The Problems With Aerospikes
32:50 - Comparing Aerospike Engines To Bell Engines
41:30 - What The Experts Say
51:35 - Future Aerospike Prospects
54:00 - Summary
Article version for easy reading and references - everydayastronaut.com/aerospikes
Today we’re going to look at the history of aerospike engines, go over how nozzles work including things like overexpansion, underexpansion and even expansion ratios, we’ll look at the pros and cons of the aerospike, the physical limitations and problems, then we’ll compare the aerospike to some other traditional rocket engines.
But that’s not all, I obtained never seen before photos and videos of some aerospikes, we’ll get opinions from some people who have actually worked with aerospike engines, look at some promising prospects and compelling concepts and by the end of the video we’ll hopefully know whether or not the holy grail of rocket engines is just waiting to be utilized or if aerospikes just simply aren’t worth it.
Special thanks to @MartianDays on Twitter for the scale engine renders! - / martiandays
And also thanks to Charlie Garcia for helping me learn so much! - / dragonrider66511
--------------------------
Want to support what I do? Consider becoming a Patreon supporter for access to exclusive livestreams, our discord channel and subreddit! - / everydayastronaut
Thanks to my Moon Walkers for helping produce each and every video! - Neurostream, Max Haot, Thomas May, Jason Padilla, Joe Leva, John Malkin, Larry D Lysinger, ArcTechInc, Blake Jacobs, Ole Mathias Heggem, Jared Smith, Mac Malkawi, Jethro, TTTA and NSS North Houston Space Society!
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I'm the cohost of an awesome podcast where we talk all about current technologies and how they shape our future! ourludicrousfuture.com or here on KZbin / ourludicrousfuture

[@JaySmith91]

Genuinely one of the best 1 hour 'documentaries' I've seen. Those on TV are always dumbed down, hyperbole, unbalanced, or full of filler B-roll. This video was packed full of well-researched facts, videos, interviews with leaders in the industry. Thanks for making this and sharing it for free with the world.

[@snuffeldjuret]

I wanted to leave a comment like this, but I'll just compliment you on yours. These type of things are in my experience frustrating to look at on TV, much better to have the teachers (sort of) approach as Tim has.

[@jimlthor]

I'm waiting on someone to rip this off..

[@palettetools6461]

This!!!

[@ddhsd]

Agree Tim Dodd has one of the best channels about the space biz aimed at laymen but not dumbed down to a 6th grade level like most TV documentaries.

[@Rattiar]

@@ddhsd Amen! And I think that is his KZbin super power: He is a smart dude who came at this from a place of nearly complete ignorance. In learning it so well from a layman's perspective, he is able to explain it to us (generally smart but ignorant folks) in exactly the ways that make sense. This is why it is better to learn basic or intermediate science from a real teacher than from the hardest core scientist (who inarguably knows it better than the teacher - but teaching is the relevant skill).

[@SakariRannikko]

Main argument for aerospike: they’re so cool Main argument against aerospike: they’re too hot

[@Tunkkis]

Jumalauta, sinne meni tunti, kun tämän kommentin lukeminen olisi riittänyt.

[@deletemii3312]

Cool > hot

[@Czeckie]

I like my engines like I like my women, cool and hot

[@ICGedye]

And heavy😂

[@Kenji1685]

@@Czeckie hahaha yup

[@artalagao3995]

I watched you go full nerd for a whole hour. You did an amazing job. I can't imagine how many nerd hours went into the making this documentary. Truly, self publishing has come of age. My hat is off to you.

[@nophobia123]

The comparison of the arrow spike engine to the rotary engine at the end of this video was brilliant

[@rogeriopenna9014]

"this is a really long video" Don´t be so modest Tim. This is not a video. This is a high quality documentary.

[@naughtyUphillboy]

Probably best on this topic.........

[@tewrgh]

How is it that one person with a camera and some video editing/animation software can make better produced & more intelligent science documentaries than multi-billion dollar media corporations?

[@naughtyUphillboy]

@@tewrgh TWO WORDS: Dedication and PASSION

[@tapio83]

@@tewrgh Probably by spending hours and hours on research and scripting and being genuinely curious on the subject.

[@otavioaugustochavesfernand9965]

Hello, my brazilian friend!

[@TechyBen]

Me: "I need to chill for an hour" Everyday Astronaut: "I got you covered"

[@nicosmind3]

I need to chill for 45 minutes. Adjusting video speed to match my needs. Modern life rules!

[@natebit8130]

601

[@turmat01]

48:04 God I love his smurk as he answers "Oh there is stuff you can do! :)"

[@Dynoids]

I really love this video, I did a 10-page report for one of my engineering classes discussing aerospike rocket motors. I only had a chance to do so much research before the deadline so it's awesome to see this full-length video go so in-depth and go so much further with research than I could.

[@FaizanShaikh-ih3uu]

Hey can you share your report if you dont mind, i am in my final year aerospace engineering and my project is about high efficiency rocket nozzles 💯 It will help my work🙏🏿

[@mayankshrivastava3554]

Everyday Astronaut has truly outdone himself on the aerospike video. What an amazingly researched video. Simulations from Stanford, restored footage from Aerojet Rocketdyne, great animations, reading through NASA's decades old documents & reviews from Elon Musk, Tory Bruno and Peter Beck.

[@holyravioli5564]

And without anyone else helping him. Like editing, researching and writing. All on his own. Or am I wrong?

[@linecraftman3907]

@@holyravioli5564 he mentioned people from his patreon discord channel helping him sift through documents

[@andrewkhan1028]

I learned so much, and I will probably retain less than half of it--this is definitely one I'd need to rewatch a couple times to understand fully... Edit- maybe half of half, if that

[@donjones4719]

Yes! So impressive he got personal comments from the CEOs of three rocket companies. More impressive is the knowledge he taught himself. And best, he processed and re-presented it so we get it all in just 1 hour. Incredible, Tim!

[@linecraftman3907]

@@donjones4719 these comments are actually from interviews. I highly suggest that you check it out

[@SkylersRants]

This is what journalism should always be like. My understanding is that the Everyday Astronaut is not an engineer of any sort, yet he has presented this issue more clearly than anyone else. I had been reluctant to watch this, assuming that it would be filled with mistakes and lacking in analysis, but I'm happy to see that I'm wrong. Good job, and thank you.

[@CatchEmCouple]

@Santina Murphy Do you have a website or link to those I wanna read up on them!

[@Deoz0311]

@@CatchEmCouple did he reply? I'd like to read up on that as well.

[@michaelskywalker3089]

Yes, the everday astronaut represents the best of the new media which will eventually replace the traditional news and entertainment outlets. I am a gen x person, so I have seen everything from radio to podcasts to this.

[@cocofilms5524]

Ya, Tim is actually a professional photographer.

[@davidr9761]

Well said! This is incredibly well done

[@CAMacKenzie]

I didn't get around to seeing this vid until Dec 2022, having been referred to it by a Scott Manley vid, so I wonder if you have an update in the works. After all, a lot can have happened in the 3 years or more since it was posted. I was really glad to see this, as I had only the vaguest idea of what an aerospike engine was, though I had heard of them for a long time, but hadn't gotten around to reading up on them. A couple of ideas I had while watching this, with regard to ablative cooling. 1) A solid fuel aerospike engine. It wouldn't likely be reusable anyway, so ablative cooling would be the way to go. That would be for a strap-on booster or for a ballistic missile. 2) For a reusable engine, a replaceable ablative section for the areas most susceptible to heat overload. The other thing that struck me was the similarity (superficial, at least) of an aerospike to the tail cone of a turbojet engine.

[@DumbledoreMcCracken]

These don't work, and will never will. The static atmospheric pressure does not push the spike wall enough, and can't (that is, there is, at most, 1 bar of pressure on the wall). The reason "research" was done on these engines because the *"engineers" didn't understand basic physics.* In effect, the only nozzles and bells, in a linear aerospike, is the little nozzles at the top of the engine. The traditional rocket bell has a higher static pressure (greater than atmospheric static pressure) pushing on the inside of the bell, making the engine work (the bell works poorly at suboptimal atmospheric pressures, but still works better than an aerospike). It would have been better if the video better explained that the Static pressure both pushes "out" on the engine bell, but also pushed "up" on the engine.

[@billstech1715]

With 28 engines on the Space-X Heavy and looking at the inward angle of the Firefly Aerospike, it looks like Space-X has accomplished the same end result which is basically to vector the thrust inward around the outside to compensate for the expansion as the ship goes up in altitude, basically what you said in the video, combine this with multiple stages and there you go!!!

[@nilsdock]

we should award a "no-bell prize" for the first company to get one to orbit.

[@wherethewildthingsarenot]

You're a genius

[@deusexaethera]

[@GewelReal]

@@wherethewildthingsarenot more like he can copy and paste text

[@t2force212]

And not collapse from the Aerospike curse in the mean time

[@parzival_rpo]

Ehre

[@kenkirtland6757]

Truly surpassed the title of “KZbin video” this is a documentary

[@bryce4724]

A doc i have been waiting for years for. i believe in the arospike we just need a reason to have an SSTO like the X33 to be worth making. if we expand the amount of orbiting stations then they would be in use

[@rs0n]

Lol, yeah this title doesn't do this video justice :p

[@aboldy]

Yes you got it there. As good as any TV doco

[@jeffvader811]

@@bryce4724 I don't think pure rocket SSTOs make much sense, the margins are just so tight. I do think air-breathing SSTOs are a little more promising, with a payload : gross mass fraction of 4.6% for the Skylon concept, compared to 2% for VentureStar and 4.2% for the Falcon 9. So there does appear to be a noticeable advantage there, as long as the SABRE engine meets it's design requirements it could be quite competitive. Of course, if we're talking more far future tech, say 100 years from now, where we could have metallic hydrogen engines or something similar in Isp, SSTO starts to look very attractive. But right now, fully reusable multi stage rockets look a little more feasible.

[@user-lv7ph7hs7l]

@@jeffvader811 Yes but SABRE and Skylon have been in development since the 90's and before that there was HOTOL in the 80's and reaction engines has more or less postponed Skylon in favor of SABRE powered hypersonic airliners. So great concept but while they where looking for money to develop SABRE, SpaceX and all that happened. So now Skylon isn't very attractive anymore. And certainly it's not gonna look any better next to Starship. I know we all want the scifi spaceship that can park in front of your house and go all the way to orbit, but it's just that. A cool sci fi concept. We shouldn't force reality to conform to what we want just because its cool. SSTO will never be great on earth. Sure someday, there'll be fusion powered SSTO and all that but not today. And also consider safety. If Skylon looses one of those super complex SABRE engines, say a bird flies into the heat exchanger at Mach 4, you're dead. Loss of thrust on either side at hypersonic velocity will destabilize Skylon and it'll break apart. So great for cargo but even Starship makes Skylon's possible abort modes look dangerous.

[@kevinlabbe8391]

I forgot to thank you for your thought provoking knowledge. You are the type that does think out of the box. The very kind of people we need in this world.

[@caspermilquetoast411]

I like when Peter is swearing you use the old fashioned telemetry 'beep' to censor him! The ultimate nerd censor beep! (quindar tones)

[@yehudalanger]

Yes. Although I think that's the talk tone of apollo

[@RobinCernyMitSuffix]

@@yehudalanger it was a switch, to stop sending telemetry while they use vox. While they were not talking, they were sending telemetry over the same frequency.

[@TheNighthawk00]

Peter Beck summarized it perfectly: the advantages that the physics promise are lost due to engineering problems. Magnificent video!

[@71Jay17]

Every technological advance has been here. Its nothing new or insightful just a fact of research, development and engineering advances. It only means that right now (maybe ever) this is the impediment.

[@MysterySemicolon]

It's probably better to compare it to the 80/20 rule. Bell nozzles are just lower on the scale and the gains of AS just don't equate to the expenditure of resources to explore when viewed through that lens.

[@Kismetix]

Well It's wrong though. Tim didn't account for the fact that you need two raptors (one atmospheric, one vacuum) to match a single stage aerospike. And with the two stage raptor, you always lose the second stage vacuum engine. I think he overlooked that not insignificant fact. The aerospike comes out way ahead.

[@MrPDawes]

Engineering science never stays still. I'm sure when the technology makes Aerospikes more viable then they will become the defacto standard. Like 3D printing has changed the way we can now manufacture these engines like never before while bringing cost way down.

[@Tuning3434]

@@Kismetix And that is oversimplifying for the fact that staging has a huge advantage on rocket efficiency, and as in the Falcon 9 / BFR, has a beneficial layout for re-use.

[@mspencer712]

That entire hour was extremely watchable and quite enjoyable -- like a well produced TV show. Very well done.

[@danielwhyatt3278]

Definitely. I should be shown on more than just KZbin.

[@Muskar2]

I agree for the most part. Really interesting and well-made video. I have so much appreciation for all the work he puts into these - I wouldn't be diving this deep into rocket science if it wasn't for these. The only segment I didn't like was the reading of some of the numbers on the comparison sheet at 36:00 - I prefer it when the numbers are kept at display while the presenter explains the context/meaning of them. I had to pause the video and try to make sense of it myself instead. I'm sorry to admit that I wouldn't have had the patience to do that if it happened many times throughout the video.

[@CompatibilityMadness]

I'm pretty confident, he's got better Experts than well produced TV show could get :D

[@alexandreboulch5455]

Amazing video! Can’t believe my eyes. I’ve been searching for more than a decade an easy explaination, without equation, for why nozzles even exist. Thanks so much

[@NineSun001]

Came here by accident, stying for the love of sapce. Great video!

[@GavinRemme]

KZbin: we're optimizing for watchtime Tim: Hold my beer

[@WQIOPA]

Gavin Remme it should be "hold my areospike"

[@maus9777]

*hold my rocket fuel

[@Fred_the_1996]

@@maus9777 hold my methanol

[@HayderAbdulridha]

It's a historical documentary, not just a video.

[@shehulsuratwala2684]

It'll be used as a video learning material for future generation. It has all the info from 1950s to 2019...

[@elijahaitaok8624]

This will probably be shown to highschoolers on Mars 150 years from now

[@kencroker6206]

I just watched the whole hour long video and it was ABSOLUTELY WORTH IT!!! You explained things so well that even though I'm a complete newbie when it comes to rocket science, I could still understand the vast majority of your content. This must have taken an immense amount of effort, and I can't wait to see what you do next. You've definitely earned my subscription!

[@fatballs148]

My Brain at 3 in the morning: plz go to sleep me: yeah yeah...but are aerospikes better than nozzles tho ?

[@DiffuseSpy392]

litterally me rn.

[@Maverick966]

IDEM

[@mas0n25]

this is me, but it’s 4:36am

[@jasonnoronha7100]

4.37am here 😅😂😂

[@adrianthe402nd]

Nozzles are better than aerospikes

[@nickbird7742]

This is what You Tube was built for, the amount of work that went in to this video is mind blowing. The way everything was explained was just right. Thank you for sharing your thoughts and experiences.

[@matthewerwin4677]

KZbin was invented to make a few computer geeks rich. Don't fool yourself.

[@karlheinz4059]

Normaly i get angry when youtuber put more then 4 advertising in one video, but if a so good youtuber like him does that i dont care

[@TheTMFD]

I’m new to this channel, but I am severely impressed with the amount of research you did! Bravo sir.

[@gooner72]

Great work mate, well done. This is a proper in depth documentary and you're really good at it.

[@bend1707]

I somehow just realized that when he censored Peter Beck saying "a**", he used a beep from Sputnik. Well played Tim, well played.

[@EeekiE]

Sounds more like the outro Quindar tone as used by NASA to me

[@EeekiE]

Oh and I think he was actually saying a*** 😁

[@wierdalien1]

@@EeekiE yeah I agree with you it is Quindar

[@jaysonl]

Looks like I'm late to the party. I haven't bothered to run it through frequency analysis, but yeah, they sound like Quindar tones to me as well.

[@jaysonl]

@@EeekiE is totally right... I ran one of the bleeps through Audacity, and it says the peak frequency is 2477 Hz... and Wikipedia says the Quindar outro tone is 2475. Good ear!

[@alfredlorber97]

Amazing job Tim!! I’ve got three degrees in Aerospace Engineering, including a PhD, so I know something about this stuff, and your video is terrific. I think your nozzle pressure section will be used in a lot of Aero classes.

[@GeorgeDolbier]

I completely agree! That section can be broken down neatly for classroom discussion. Masterful storytelling

[@lashedandscorned]

Keep doing amazing things with your education!

[@EmilianoGirina]

Even after 4 years this is one of the most amazing video about space engine available on YT.

[@MP-kg3yt]

Just awesome how professional these Videos are. Really entertaining to see how this stuff works!

[@MattLowne]

"Huh, it's going to be difficult to summarise the aerospikes vs nozzles in a 1 minute video. Wait a second, it's a whole hour!" Serious props, this must have taken a huge amount of effort! The animations are really slick too, I always found it hard to explain the concept of how the "virtual bell" works with aerospikes

[@Iron-Jupiter]

Hi matt

[@santiagorodriguezjr6961]

BOTH OF MY FAVORITE KZbinRS ARE HERE!

[@SeizureSalad]

cmon tim, heart this comment

[@rinyjiao435]

hi matt your space shuttle video was cool

[@jaka7418]

Matt just a regular viewer hell yea

[@rahulshah2852]

So 'when its done' finally arrives.

[@rogeriopenna9014]

He does not follows SLS timelines.

[@rahulshah2852]

@@rogeriopenna9014 I am okay with him following any timeline as long as he releases all his videos at when its done. :)

[@bdietz2]

I'm impressed with your research and your presentation. You did a great job of explaining a complex subject. I used to think you were just a gushing and enthusiastic young space fan building a neat tv truck, but I now see you are a lot more mature, talented and hardworking than I thought. Congratulations and keep up the good work. A subscriber.

[@L4rthan]

Man you're so good at explaining, you could go straight to university and teach a basic physics course. Mad respect!

[@Wisald]

One hour long The absolute madman

[@livethefuture2492]

perfect full-length documentary.

[@heysiri4935]

I’m only 15 minutes in, but I can already tell this is your current Magnum Opus. You’re doing a fantastic job, Tim! Edit: Yep, this is the best video you’ve ever made!

[@rosswaring2835]

Great job Tim! You made some tricky concepts easy to understand and grasp. Nice comparison to the rotary engine to grasp the intuition of what is going on. 👍🏻❤️

[@rogeriopenna9014]

Tim Dodd. Started as an KZbinr. Became a famous interviewer Became an awesome documentary producer. What's next? Mars colonist?

[@Muuip]

He will most likely engineer the next level of rockets himself .... then visit Mars.

[@hirvielain9013]

Tim develops a true friendship with Elon over time and Elon will let him board the Starship one day for free probably.

[@thedamnyankee1]

No, He started as a Photographer who bought a russian space suit on a whim.

[@jdudleyh]

@@hirvielain9013 And I think Tim would kindly decline the offer. :)

[@donjones4719]

I saw him quoted in a mainstream article as "an industry expert," which is what he is now.

[@peteoconnor6388]

That didn't seem long at all, I was really surprised an hour went by.

[@lucaspalladinogonzalez9596]

same man, thats when you know this documentary is amazingly made

[@BAZZABB]

Thanks Tim. A worthy educational hour!!! I love the comparison between the Rotary and the Piston engine. I do believe that a well engineered and reliable AeroSpike engine is just a matter of time. Given the advancements in materials science, modelling, 3D printing, some of those engineering hurdles may be able to be mitigated, if not overcome completely.

[@andrewlavey6992]

A very extensive and compelling video to watch. Well done Tim & team.

[@PhotonBread]

When I see videos this long I always think man I’m never gonna get through this. Then it ends and I want more. Life

[@clavo3352]

Right? Thank goodness for being able to speed up the delivery. I listen at 1.75 speed for most of the stuff and then slow it down to understand the statistics etc.

[@pequalsnpsquared2852]

FINALLLLLLYYY!!!!!! Everyday Atronaut, you are the best Well well well well done

[@DavidLightman]

Amazing video! i watch the whole 1 hour, subscribed, excellent work, i can't imagine how many hours it took, but it worth it, most of my questions and doubts about this engine has been answered, thank you.

[@nyghl]

This content is really valuable because i'm a simple man, with 0 pre knowledge in this area but still didnt skipped even 1 second of the video. It is awesome and thank you for this awesome content!

[@wardenmetallicred]

I like how when I watched the unedited Elon Musk interview I didn't understand what he was saying and now I do.

[@mrmonkeboy]

I thought Elon took such a random question really well. After talking about Starhopper and Starship for an hour, suddenly being thrown a curve ball aerospike engine question -- he was a good sport and knew his stuff.

[@janos71]

the part with the: "mach diamonds are a side effect of..." was really new and interesting to me

[@bimblinghill]

There's a great Scott Manley video which explains this in detail.

[@janos71]

I am surprised that I haven't seen it yet :D but maybe i just cant remember

[@coltoncollingwood9508]

@@janos71 Look for the afterburn bloom from a SR-71 Blackbird, it also has the shock diamonds

[@markzaikov456]

I was really curious about it before as well, and kinda figured it out myself. But my other go to rocket science channel Scott Manley mentioned it and gave an in depth explanation.

[@wardharrah55]

What a great video!!! Thank you for putting this together, I learned a lot from watching this today...and it was nice to see our home base represented! Good old Wright Patterson AFB! I live just a few minuets away in Springfield Ohio out in the Township...right on the landing pattern for the C-17's stationed there. You've got a new subscriber today! Not that you really needed it...LoL I'm looking forward to exploring your channel! Thanks again

[@bradenwolf2179]

This is excellently described. I now finally understand specific impulse, something I have struggled with

[@boakyeduan563]

Before watching: jeez this is loooooooong After watching: that’s it? How can it end so fast?

[@Ethan.YT.]

@@robhobsweden It seems wrong that it is gravity but it seems like it really is gravity

[@lornetontegode6986]

I've been reluctant to watch it since it's so long but yeah, it went fast.

[@davidelliott5843]

Nearly a year later, I’ve just watched it again. Still cool and I still want to know if an alumina spike would cope with the temperature.

[@Waffel07]

Him using quindar tones to beep out Peter Beck swearing is such a lovely detail! :D

[@starhopper457]

Very deep here... I've had to watch this twice, and some sections a third time to make sure "I get it"... very well done Sir!

[@rangerg7278]

Wow!! I am a science teacher interested in how rockets work, not an engineer, and I still understood all of your video. Very well done, especially getting data from actual source material and conversations with those who have achieved workable products.

[@EverydayAstronaut]

Timestamps for mobile users: 6:20 - How Nozzles Work 16:00 - How Aerospikes Work 19:55 - The Problems With Aerospikes 32:50 - Comparing Aerospike Engines To Bell Engines 41:30 - What The Experts Say 51:35 - Future Aerospike Prospects 54:00 - Summary Also sorry about including my ignorance on mixing temperatures 😂 when I realized that a few years ago, it kind of blew my mind but I hadn’t really thought about it too much I guess. And with no formal education or even ever having taken a single physics class, I definitely lack some of those basics. But I thought it was fun to include so people can remember that it’s ok to keep learning at all times! But yes everyone, I understand it now, you can stop explaining it to me 😂

[@space_fella8206]

Can you pin this? Ive already watched multiple times, and its great

[@rkpetry]

*_...not the reason my 'thumb' is feeling historically light but advan-tech heavy..._*

[@AlexK-ty4fj]

Amazing video

[@JustFamilyPlaytime]

Great video - perhaps could be even better if you maybe found a better way to present all those numbers in your comparison. TL:DR Learn to graph!

[@muskyelondragon]

Great work on this 👍

[@ralphwagenet852]

First rate work; you obviously put a huge amount of effort into this, and it's greatly appreciated.

[@NoblePineapples]

I came here after watching your tour of Stoke Space's facilities and their aerospike engine. This was a very informative video, thank you!

[@alexn3574]

I really enjoy how in depth your videos are, and how you make it easy to understand with the videos and pictures as you describe what's going on.

[@angc214]

46:00 I love how you bleeped him out with a quindar tone.

[@MarkoLomovic]

I like how sometimes it bleeped but we still heard everything

[@Jimmeh_B]

Yeah that was a really nice touch. I chuckled.

[@basveltink1001]

I read this comment right after the first bleep lmao

[@greghansen38]

I've watched shorter videos than this that were a lot longer...

[@C-S-J]

Couldn't agree more. I was actually surprised to see it was over an hour long, didn't feel anywhere near that long since I found the topic very interesting and the presentation was excellent.

[@cadgecorp]

Same mate

[@clickbaitfishing7787]

This is going to be my standard go to comment on everything I watch from now on

[@wardharrah55]

My Adult Children: watch nothing but fails and car crashes on KZbin Me: Why don't watch something like this where you might actually learn something?

[@user-cd4bx6uq1y]

Like vsauce hole vid

[@tulsatrash]

Thank you very much for making this I learned a lot, and so did the people I watched it with.

[@denislemelin7653]

It’s all so fascinating. I can listen and watch this stuff all freak’in day !

[@OscarLopezMartin]

Dear Tim, I've been following you for a while now and I am impressed by the quality of your documentaries. This one is fantastic and provides a great insight on the aerospikes. As an aerospace engineer I can only agree with you that aerospike technology doesn't have enough TRL to be commercially viable in a short term. And even worse than that, there is no reason now for a SSTO given the engines we have and the reusability factor. Nonetheless, I am a dreamer, and we won't be able to use multistage spacecrafts when landing and taking off from other planets. So, I still can't avoid thinking that the future of rocket engines is some sort of SSTO spacecraft powered by aerospikes, or increasing the number of steerable engines so the total plume could be fully controlled by hundreds of small engines, or some sort of adjustable geometry nozzle. I feel that the aerospike concept is like the electric car at the begining of the 20th century. It was way ahead of it's time. Looking forward to see your next documentary!

[@donjones4719]

Starship is of course SSTO from Mars, and since watching this vid I've been wondering about how the positioning of its vacuum optimized engines interacts with the exhaust of the center 3 sea-level engines. But with Mars having such a thin atmosphere, there's so little difference between surface-level and vacuum.

[@trimeta]

The only time you need an atmosphere-compensating nozzle rather than a bell nozzle for SSTO is if you're taking off from a body with a considerable atmosphere. And as this video shows, even Earth's atmosphere isn't thick enough to make aerospikes better for SSTOs. In other words, even in an SSTO-from-other-planets future, you'd still only need aerospikes to take off from Venus and Titan. And those bodies have other considerations that would probably outweigh the problem of "my vacuum-optimized bell nozzle doesn't work here."

[@qm_rev]

I am with Oscar on this one. As Tim explained it, bigger engines are relatively easier to keep cool. If we are serious about space exploration, we should expect larger and larger rockets with each generation. So, by the time our space ships are wider than football fields, aerospikes might not look so bad... ;-)

[@donjones4719]

@@qm_rev Do those enormous ships in Star Wars have engine bells or aerospikes?

[@Appletank8]

Don Jones Most sci fi spaceships have bell nozzles, though the freighter class of the Millennium Falcon is unique for having a flat bar behind it, a possibility that some sort of aero spike is being used.

[@iain1969]

This WHOLE video I was thinking about the rotary engine as a FANTASTIC analogy and was planning to proudly type a comment and communicate this stroke of pure genius to you and the community .... however you have RUINED my day by selfishly plagiarising my idea in your conclusion! Great video mate - outstanding work.

[@ayasaki.pb_787]

This is some advanced topic, I have to watch it twice to understand the concept. Amazing content.

[@maiklorenz9348]

Also i want to admit, that this was the best researched video i have seen ever. Thanks for this crasy amount of researching Work, thinking of the best concept is always worth it, even if it turns, out, the concept is not worth it, yet.

[@Kumquat_Lord]

I know you have to put ads, so thank you for putting them in the transitions where they don't interrupt the watching experience.

[@MVHiltunen]

"My tone change from >Aerospikes suck> to a little more neutral stance on the subject." It means you've acquired real knowledge and engineering perspective. Good job.

[@stefanlukac4269]

I am interested to Space my whole life. I thought I knew a lot about this topic, but then I've seen your videos. Now I can update my library of knowledge

[@lisahogholt9713]

as an aerospace engineering student, i was looking for an explanation of how aerospikes work (my professor wasn't exactly dismissive of them, but he didn't spend nearly as much time explaining how they work as he did with bell nozzles). this is so much more than i could have asked for! hopefully in the future we will have advanced enough in terms of materials and production technologies that the aerospike will actually become a viable, advantageous option. they seem so cool!

[@ashh3051]

22:27: I thought this is pretty intuitive. If I mix a glass of hot water and cold water together, I get warm water. I don't get even hotter water.

[@ganeshsreedhar4657]

Hell yeah

[@stargazer7644]

It's like he's never used a hot/cold faucet on a sink.

[@gohealthy5925]

I m a hawker, i was taught by my senior to add oil to over heated oil to average it temperature. So one time i forgot about my wok of oil that is heating, it turn into frame, so i did what was taught，n d fire go off. Note must be adding oil n not water, water will cause explosion!

[@bukiyouneko9863]

Honestly, this is a common mistake for engineers though I don't understand why. You see it allot with hybrid technology, they'll add the power of the electric engine to that of the gas engine and say the car has 900+ horses but yeah... it dosen't work like that.

[@tyty8484]

Ayyyy, Nerd "Culture" in a nutshell. "That's the power of math people!"

[@jimbarchuk]

"It's never too late to start learning thermodynamics." 22:nn

[@rickdeckard1075]

that...was a strange statement to put in an hourlong vid about rocket engine designs...

[@lucasamadsen]

13:30 You can see the shockwave expansion mentioned previously during engine start. Pretty cool!

[@SinanAkkoyun]

youre the first one explaining this greatly and in detail, thank you very muc!

[@ugowar]

So, to recap: Aerospike engines: *am I a joke to you?* Planet with 1g surface gravity and 1 bar surface pressure: *yes*

[@GeorgeDolbier]

now if we lived on Venus or Saturn.....

[@frbe0101]

Would be nice if KSP has bigger aerospike that would make sense on Eve

[@pfisherking]

@@GeorgeDolbier Or Titan.

[@GeorgeDolbier]

@@pfisherking Ooooh... now _there_ is an interesting problem. The 1.45x atmo. pressure might not be enough to push the economics over to favor aerospike, especially since titan has gravity low enough you could just wack a rock into space with a baseball bat. If it weren't for the ~200km worth of that thick atmosphere you would have to hit that rock through. The thickness, combined with surface pressure, and therefore the wide variance between surface pressure and vacuum, just might make the aerospace a more efficient design for Titan

[@Kismetix]

But you still need two raptors - one atmospheric and one vacuum - to match a single aerospike SSTO. Tim should have divided the effective TWR of the raptor by 2 to get a straight across performance comparison. And you always lose the second stage vacuum raptor, it is not recoverable. I think Tim missed all that rather important aspect of the economics of the comparison.

[@Roodj1]

The fact that you realized that you needed to learn more about the subject after learning a little is something a vast majority of people don’t do. I appreciate that.

[@pat8437]

Amen.

[@DanielePauli]

It's called intelligence.

[@DanYoo-koolerdanyoo]

The Dunning-Kruger effect

[@ezaspie03]

It was nice he referenced the Dunning-Kruger effect, as so many are effected. Yet so few even know about dunning Kruger, let alone realize they're doing it themselves.

[@olliegueret2963]

Curious Droid did an amazing segment on this a few years back! Still though, great job Tim!!!

[@christinaeneroth675]

You are givning very cleat and thorough answers to question I didn’t know I had!

[@borisssman]

A documentary with time stamps professional interviews, a summary, great explaining animations, a natural view, researched numbers and data and of course Tim dodd the everyday astronaut. Thanks for this awesome film

[@MrAbi1998]

Tim, please never stop making long videos or be afraid of making them. If you had even made a 10 part series, I would binge on them in one sitting. Thanks for all the hard work you put into these videos.

[@handsomebassman]

The effort you put into your content is incredible. I cannot thank you enough for the endless hours of learning and entertainment.

[@MrGaborseres]

Tim.... It took me a while.... But I'm hopelessly hooked watching you explain all this good nerd stuff 👍👍👍 Thanks for all you do 👍

[@ryantwombly720]

Excellent deep dive. Tim’s superpower is getting people to talk in more technical detail than they intended. Keep it up!

[@RaphaelBrandaoS]

So aerospikes are like graphene: the physicsts love it; engineerings hate it

[@michalisdiakonikolis240]

Why do engineers hate graphene?

[@kineticstar]

@@michalisdiakonikolis240 to hard to produce on mass and implement. All the theoretical applications need to be tested extensively to figure if this could be a viable option for the current standards they are ment to replace.

[@dirkbester9050]

That is just a really bad analogy. 2 stage reusable vehicles make SSTO look dumb and therefore make aerospikes look especially dumb. Meanwhile graphene is just new tech in its early days. There is no reason to think it is unusable, no matter how hard it is to work with at our current tech level. We are hitting the end of Moore's law as well. We are going to have lots of time for alternative tech to catch up if it is better.

[@alephkasai9384]

@@whannabi Trying is the keyword. Last time I heard of graphene armour was this level iv plate but they later changed it to just being a composite. Maybe that was carbon nanotubes

[@kiprs]

engineerings lmao

[@georgesmith827]

Eureka! At exactly 10:08 my mind finally comprehended Flow Separation! Thanks everyday astronaut.

[@therealreasons9141]

Personally I'd like to see an aerospike with a surface texture designed for drag rings, kinda like a golf ball. Like an inverted flow separation.

[@solopine9624]

TLDW: Because we have stages, we don't need a jack of all trades engine, when we can have a master of sealevel and a master of space engine

[@lewisyeadon4046]

@Will Swift if its a vertical rocket, because an SSTO is literally impossible unless its a tiny package like the mercury capsule (and even the Atlas booster dropped engines), or if it's a spaceplane, they are currently completely unworkable For instance, the closest model we have, Skylon, will use air-breathing and oxidiser fueled engines rather than aerospace because, like vertical rockets, it is simply far too heavy to build a practice model, it would be way more expensive than the Shuttle per kilo into orbit, and at that point you may as well just use the current Falcon 9 launches They're cool to think about, but the heating issues far outweigh the ease of developing a normal rocket bell, unless you want to spend almost half a century developing your spacecraft like Skylon, the X-37 and every other launcher that uses highly unusual engines

[@randall172]

@@lewisyeadon4046 the top section of starship (no bottom booster) is a SSTO, it is capable of getting to orbit.

[@Jognt]

"If reusability offered a clear advantage, everyone would have developed them." - Pretty much everyone when SpaceX announced their plans. Though with aerospikes I think it's not so much a solution to a problem, it's a problem people want to find a solution for, because it'd be cool.

[@ShaunRF]

I would say that reusability had pretty clear advantages from the start, hence why it has been worked on by many parties over the course of decades. Its just that the challenges to getting there were very daunting.

[@junovzla]

@@ShaunRF more or less the same thing happens with aerospikes

[@ShaunRF]

@@junovzla Not really. I'd say the known advantages of reusability far exceeded the known advantages of the aerospike. It really only has one advantage, so all that effort doesn't come with much of a payoff.

[@daniel_960_]

There wasn’t that much rocket development going on in the near past, most development just recycles old technologies and concepts. I think for reusable rockets you really need some high tech technology, which wasn’t available in the past when there were big developments in rockets. So now spacex came along and decided that they want to do something completely new and from scratch and realized that all the technology was there, they just had to do it.

[@SRFriso94]

Not really. Reusability has also been pursued since the '60s, starting with the Gemini wing that Amy from Vintage Space loves so much she has it tattooed on her arm. Then there was the Space Shuttle Program, the entire sales pitch of which was based on reusability, even though now that we can calculate the cost with hindsight, refurbishing the SRB's was more expensive than just buying new ones and the fact that the shuttles themselves needed to be largely taken apart between launches drove up costs as well. Propulsive landing, that was what everyone said would be impossible, and SpaceX was mocked open season style, right up until they pulled it off. For now, we're not even close to getting maximum efficiency with bell nozzles, which are far simpler to develop and work out their teething problems. SpaceX has only just cracked the holy grail of those, the full flow staged combustion cycle, and it has yet to fly beyond test vehicles. And because those are far from done evolving, there is just a lot more to be gained for a lot less expense by investing in bell nozzles. Maybe when there are no more places to improve those, and aerospikes are still more efficient on paper, then we can look again.

[@cyclesingsleep]

Excellent video...even the third time watching/listening! Thank you, Tim & crew!!!

[@bramfokke1460]

Thanks for the explanation of why Isp is measured in seconds. I never really understood that until watching this awesome video!

[@rocketman4315]

Finally, the masterpiece is ready!! I hope you get this on Netflix as a full length documentary!

[@harrymack3565]

YEEEEEES

[@DurbanFlyboi]

Me in Count Dooku Voice: "I've been looking forward to this"

[@nvan7891]

A regular voice would be a lot less gay.

[@Round_Slinger]

@@nvan7891 💀💀💀

[@KSparks80]

WTF is Count Dookie?

[@nvan7891]

@@KSparks80 what your mom calls me.

[@caav56]

Or, in the words of The, "I always at wait for this day".

[@leevibyman2053]

Thanks for the video! First time I've seen this channel, but it seems very interesting

[@Bramon83]

The rotary reference is so spectacularly spot on

[@CombatJak]

Aerospikes: The Rotary Engine of the rocket world. Damnit... I posted this comment and seriously a minute later, you said it in your video. XD

[@noobplayer_23]

And both of them really needed to have some kind of comeback

[@sparrowlt]

Wankels are also extremelly fuel inneficient..

[@WlerickBigotOfficial]

@@noobplayer_23 Check out Mazda latest news, Rotary comeback is confirmed ;)

[@WlerickBigotOfficial]

If Aerospikes are the Rotary Engine of the rocket world, I seriously cannot wait to see the birth of the Electric one => Absolute perfection =O Just imagine a ioniq propulsion device as powerfull as a Raptor engine, and powered by a nuclear fusion reactor *MINDBLOW*. Would love to see this =)

[@onebronx]

@@WlerickBigotOfficial A space elevator would be the "absolute electric perfection".

[@karlstathakis7786]

Tim, your work here is extraordinary. I can't believe how well-researched this video is. And it's incredibly well-presented. Well done.

[@scottorton482]

I have loved the space program since my parents made me stay up to watch Armstrong take the first step. I was 6 1/2 years old. Yet no one (not even the NASA technicians) have ever explained the combustion chamber physics to myself. Thank you so much. However now I know why when you watch the launch of one of the Apollo's Saturn V. Do you see the flames diameter. At launch it's very much approx to the size of the bell nozzle's diameter at the end of the nozzle. Yet view the Saturn V at high altitude and the flame from the nozzle is huge like the wake of a ship. Thanks

[@King4s]

Love this video. All this nerdy stuff, got me to understand rocket engines a lot better.

[@graeme011]

An extremely well researched and informative video!

[@riparianlife97701]

"R&D is expinsive and time-conshooming." I love Kiwis.

[@tophatv2902]

What is the joke?

[@sadface7457]

@@tophatv2902 It the acent.

[@ConfusedPlushiee]

them and the sco'ish, best ever

[@skimiii]

I realized how good this video is when on the bit with the Elon Musk interview I understood what he (and you) were saying. Awesome work!