There are people that try to stretch a 1min topic into 15min to gain more watch time and then there is cramming a 3 hour lecture on ROCKET SCIENCE into 49 minutes...

Absolutely incredible. I’m speechless. Can’t believe I actually just watched this video on UKposts for free...

Me before the video: “gosh 50 mins? Better be good.” Me after the video: “gosh 50 mins? Why so short?”

The fact that the F-1 holds up as well as it does despite how old it is speaks volumes about the sheer engineering that went into the Saturn V. Truly a beautiful craft that I hope will always be remembered in this new era of spaceflight ushered in by SpaceX and beyond.

It's so good to hear "we'll talk more about that in a second" than "we'll talk more about that in the next video"

This is what I was hoping the internet would be. Thanks for your hard work!

The fact that this is free to watch is insane. Excellent work!

BAM!!! That's a high grade script, animation and delivery! Well done!

This is probably one of the best videos on rockets I have ever seen. The amount of information you crammed into 49 minutes is crazy. Thanks!

Me: "I'm definitely not going to watch the whole video" *49 mins 1 sec later* "Ups.."

Best 49 minutes I've ever spent!

This is the second time I am watching this; I am slowly educating myself (or NASA and others are educating me at You Tube) in orbital mechanics and you are educating me in rocketry--for starters. I also want to complement you in the way you present. As an ESL instructor in Asia for nearly 20 years, I understand the challenge of explaining ideas to people which are complex--in your case, because it's rocket science, in mine, because I only use English--and my point is, you have a way of talking that is clear, emotional (difference in voice pitch and expression delineates concepts more easily than in monotone--the way many science teachers speak)--and you repeat, Tim, which is essential. I could probably help you with the writing; maybe when I have extra cash, I will join on Patreon and give ideas. But, thank you, and excellent job. Your knowledge alone earns you a valuable seat on the Dear Moon flight. Congrats on that! You deserve it.

I'm retired from a technical career. Over the years it was clear, whenever I was given a technical briefing on a subject I was unfamiliar with, and the person giving the briefing was unable to adequately explain the subject in "layman's" terms, it indicated that the person doing the briefing did not truly understand the technology. It is obvious that that is not the case here. Excellent orientation! Very impressive!

As an aerospace engineering student, I can say that some of this video is basically a sophomore class, but the real propulsion stuff, that’s straight up senior year content, this video is a senior year Aerospace engineering lecture. Here’s the classes you hit on: Intro to Aerospace Engineering 2 Thermodynamics Propulsion Advanced space propulsion

This video is a timeless work of art. I plan on watching it many more times. Thank you so much for making it.

I would just like to say that I appreciate the production value of your videos. You make it easy to follow along, even though you're explaining highly complicated topics to lesser thinkers like me lol

Upvoted because for the first time ever I heard an understandable description of specific impulse.

Is this video the king of everyday astronaut videos?

I just discovered your channel. Thank you for the deep dives. I have learn a ton from you over the past week or so. Keep up the great work

Brilliant explanation of the different types of rockets in a simplistic yet informative manner. Great work, looking forward to seeing the future of rocket development thru your eyes.

Ok i must say you have surpassed yourself , a very complex subject simple explained and visualized! Great Job, probably the best video of you yet!

Best 48:45 mins:secs that I've spent in 67 yrs. Well done!

All the time and effort put in this video is insane. GREAT WORK!

And lastly-This video is truly one of the greatest videos on the Internet!

Man, this video has a LOT or work behind. Thank you Tim.

That honestly didn't feel like 49 minutes. This was so interesting and well done. Keep it up Tim. We really appreciate it.

I remember watching this thinking the raptor numbers were aspirational that would never be achieve. Boy was I wrong, we are already past those.

By far your best effort yet. Thanks so much for your easily digestible treatment of these complex engines.

You know, when people say "it's not rocket science", I hadn't realised the bar was quite that high.

Me at first : 49 mins ?!!! Me after 49mins : "Definitely worth it"

38:11 As for current time, seems Merlin engine has proven at least 10 times reusability with real flights, after 10th launch of B1051

Amazing work on a complex topic. Fanatically educating. Really appreciated the quality of your production and script. Great work. I know you put a lot of effort into, first learning the details of the cycles, but also then gathering all the information together on the different rocket engines and putting into tabular and graphical form to help us understand. Your enthusiasm showed through. Your explanation is next level excellent for people approaching this topic for the first time. I found this interesting and completely engaging to watch. BTW I was in high school during the Apollo program, living only 40 miles from the NASA test facility in Mississippi. I got to see an S-1 stage test firing, full duration of those incredibly deafening F-1 engines, from one mile away with the press. The sound pressure rocked the NASA bus from side to side. I chipped my hands around a friend’s ear and shouted instructions from one inch away at the top of my lungs on the photography we were doing. He was unable to hear me. The legs of the slacks I was wearing were flapping as if a wind was hitting them. It was completely calm. The flame shooting sideways out of the flame bucket was a few stories High and I guessed about 700’ long horizontally. It was wickedly ferocious looking. It’s been a little over half a century now but I’m still impressed by my memory of it. I later flew down to the cape and watched the final flight of Apollo, Apollo 17, lift off at night from 10 miles away. We could barely hear it by comparison at that distance, but it lit the sky up like a sunrise. After staging with the hydrogen burning second stage engines, it looked like a breeding start moving rapidly through the constellations. Many years later, during the Shuttle program, I saw one reentering the atmosphere late at night from Gulfport Mississippi heading south to fly over the Gulf of Mexico toward Florida at an altitude of 35 miles at a speed of 5000 mph. I got that information the next day via a phone call to the Johnson Space Center. It looked like an orange meteor with a long white tail of ionized gas. It casts moving shadow under a bright streetlight. Two minutes after it faded out over the Gulf I heard a characteristic double sonic boom. I never saw it launched though I drove down to KSC and waited once. I never had another proper opportunity. Hopefully the SLS will become a flying vehicle one day, assuming a lot of things, and I can go see it. I have a much longer way to go to beer there these days. I now live in Iowa, only about 2-1/2 hours south of you! SRBs are very very bright. I saw the launch of Voyager 2 in 1977 from 4 miles away on a tour bus on a sunny summer Saturday. It like looking at two Suns, the pair of solid rocket boosters strapped on the Titan rocket. Of course those were much smaller than the ones on the Space Shuttle and what will be on the SLS. I’m looking forward to seeing if I can get as close or closer to a launch and get “blinded” by the light. We’ll see…🤷🏼‍♂️(Wow WOW would I like to see a full up flight of Starship some day too. That would be incredible. The noise!)

This is a contender for best video on youtube for the year. Astonishingly good

Amazing how you were not only able to inform me of the basics of rocket engines, but you kept my attention for the entirety of the video. Tough thing to do these days, absolutely wonderful video.

Tim, do I need to mention how much we appreciate your work and especially the consistent use of metric system? Thank you!

Now this is a fantastic video! Thank you for your efforts. Very well done. Cheers.

The professors in my aerospace engineering program didnt deliver this info a 10th as well as you have. And this video was free, where as my degree... was not.

Wow super interesting video man. Didn't even felt it's 50 mins. Thank you

Thank you so much brother , this simplified explanation was so great for me . Keep going 🔥

As a father, I lost it at the “fathom” remark. Well done. 👏🏻

People like this are a gift to the world because there is so much to teach and learn now and they help us put it all into the right context while making us curious to know more.

No. Because raptors commonly optimize for small agile males and larger females able to carry more. Thus, they would be queens. Good job on those animations!

I've never felt more drawn to join a patreon for a yt channel than I am for this one. Truly inspiring stuff

Seriously one of my favorite videos on the platform. A close second is drachinifel’s video about navy ship boilers.

And I was just about to go to sleep......... I would have stayed up for 2 hours if the video had been that long. This was just amazing.

Never clicked so fast. been waiting ever since you announced it on OLF.

Great video. Didn’t know if I could sit through a 45 minute UKposts video, but it was so well done and so much good information presented so well. Thank you for putting the time and effort into this.

Amazingly well documented and presented. Fantastic

despite being 49 minutes long, I was enjoing it so much it felt really short.

5 freaking months for this? 100% worth it

@Everyday Astronaut Best video yet! Very detailed and informative keep up the good work!

Crazy how you can explain in a easy way such a hard matter, amazing video 🔥

This is what I call good journalism. Thank you Tim

Best animations detailing different engine types. Super good job!

This helped me prepare for my spaceX interview! Thank you for your hard work!

This is so awesome so glad I found this channel thank you for doing what you do

"Rocket science, like all things, is a complex set of compromises." -- best line of the whole video. One should not take lightly the expression, 'It's not rocket science.' again. Rocket science ought to be applied to every day thinking really. Balancing proportion, Goldilocks principle. Deep video. New sub.

Wow! So much information coming at just the right speed for comprehension, the time flew by! All in one video was the right call

Just about the finest video I've seen you do, congrats!

Tim, this is a masterpiece. Thank you so much! You are such a excellent teacher. All the best from NC.

"So why did spacex use methane?" Thrust is blue and look cool

My sister asked me today to help her with a presentation about rocket engines, so this video came at exactly the right moment. It's really impressive how you managed to explain that deep topic with so much detail, but in a understandable way. Most videos about engines I know are to basic and don't go into so much detail. Amazing work putting this together! Thank you very much for this.

I watch this video about once a month. It's still just as fascinating. Excellent work!

Incredible amount of work put into this channel. Thank you

4:28 I like how you spent at least an hour blending their faces on the picture for just 3 seconds in the video.

Einstein said time is relative, today I experienced it. Never felt 49:02 minutes pass so fast.

You explain Rocket science in a way that I could say "It's not a rocket science dude! It's easy!" Great job! Please do more.

You are the first person to make specific impulse make sense. Everyone else is just like, well it is in seconds because that's how the math works out.

This was very well explained. The visualizations were very helpful.

Excellent! When comparing fuels, it’s more appropriate to compare characteristic velocities as the specific impulse is dependent on engine architecture. Keep up the great work!

8:06 "There are a few ways to start a gas generator engine but will be done in an another video" *video is literally almost an hour* that my friends is how complicated rocket science is, and it is not even the tip of the iceberg.

I feel like I should have earned college credits for this.

Elon watched the video and provided some additional input in this tweet - twitter.com/elonmusk/status/1132386984444383233?s=20 "Great video. Couple notes: Raptor designed for subcooled CH4/O2, so propellant density & thrust increase up to ~8%, as needed for mission. 380 Isp & up to 50% thrust/weight improvement over time. Merlin thrust/weight doubled from V1, but Raptor is closer to optimum." and this one - twitter.com/elonmusk/status/1132389917722419200 "Propellant stays same, but almost everything else improves. Fundamental goal is minimize cost per ton to surface of Mars."

Great video, Tim! Watched it twice with the same amount of joy!!!

Thanks for putting the hard work in for this video. I had no idea that rocket fuel pumps were turbo powered. I'd assumed they were electric. Learned something new. Also very interesting were the difference in fuel properties and the explanation of why CH4 is a good compromise. Well worth the watch and those 49 mins flew buy.

Info #1 and #2 RD171 actually flew almost 100 times. Much more than F1 Also, the RD170 (differs from RD171 basically with relation to the gimbal direction) was able to achieve a peak pressure of 306,2bar at chamber pressure.

I can fill in some of the knowledge on Metallurgy, if you are interested. Basically, the mechanism by which metals fail, or "yield," is by the propagation of imperfections in the crystal lattice. The imperfections are called "dislocations" and there are usually millions of them in any cubic millimeter of metal. Dislocations tend to move more easily as you raise the temperature of a metal, causing yield strengths to decrease with higher temperature. The methods of strengthening metals generally center around trying to halt the motion of these dislocations, either by adding alloy elements which tend to stabilize dislocations at the atomic level (such as adding carbon to steel), or by precipitating secondary phases (like small crystals within the crystal) which act as roadblocks to dislocation movement. Secondary phases are usually precipitated by raising the temperature of the metal and aging it for a certain duration. Aluminum is an example where this is very common. Metallurgists have determined the proper time and temperature to age metals to get the maximum strength. The longer you age, the larger the precipitates grow. If the precipitates are too small, dislocations cut through them. If they are too large, dislocations will bend around them. If you age at the wrong temperature, or the wrong combination of elements, precipitates will form along grain boundaries instead of inside crystal grains, which doesn't add strength, and can weaken the metal. Precipitates must be fairly small, and uniformly spread throughout the crystal in order to add strength to the metal Precipitation hardening is especially common in Aluminum alloys. Part of the reason aluminum is fine for airplane skins but not good for engines revolves around the fact that precipitation hardening is lost once you raise the temperature above a few hundred degrees, as the high temps will cause precipitates to grow, combine, and migrate to grain boundaries. You mentioned work-hardening of stainless steel. Work hardening is a mechanism where you basically limit dislocation movement by adding a whole lot more dislocations, and forcing them to move until they run into each other. By deforming the material, you push the dislocations until they start to stack up, which gives resistance to further propagation of dislocations. The downside of this is that you lose some of the metal's ductility, which is the ability to "bend before breaking." This means that if you have sudden, large force on your structure (shock load), it is more likely to fracture rather than bending or denting. No doubt the engineers at SpaceX are aware of this, and have adjusted their safety factors and fatigue analysis numbers to compensate.

Oh my god my dreams have come true. I have finally learnt how rocket engines work!!

Thanks, Tim- Nicely done, very clear explanations of a complex topic.

This is the most interesting online class I've ever taken. Can't take my eyes off the screen. Keep it up.

Great video, loved the fathom quip, you slid it in quite nicely.

Love your videos. Me and my dad are hooked on rockets. We watch every spaceX livestream. Really appreciate you putting out these videos.

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

If cars can be rated in horsepower, can methane powered rockets be rated in cowpower?

First of your videos I've seen. I liked it so much that I subscribed without hesitation.

That's a really beautiful science filled presentation Thank you for the animation, made it a lot easier for newbies like me follow along rocket science.. awesome

RD-171 still flying on Zenit rocket, 84 launches (last in December 2017) !

You deserve awards for this work. Truly outstanding, Tim.

Had to watch this again for the large amount of information to sink in. Well done, and very well explained!

I am doing some catch up on my knowledge of the current progress with spacex, thanks for making this incredible historical record of our progress for folks not in the industry.

Girlfriend: What kind of clothes should I wear? Me: sounds like a methane fueled full flow staged combustion cycle engine is a good fit

I almost never watch a video longer than 30 minutes, but you kept me interested! Awesome video!

Very good explanation of the different types being used. Well thought out with enough detail to get the gears whirring. Thanks!

Really Fun and Informative Video, Thanks for Making it!!!

Thank you for making this!

Three months in the making. Totally worth the wait, Tim!

Great job Tim. Your explanations are very clear. Combined with the excellent graphics this is a very instructional video. Keep up the good work.

dude this is the starter pack for learning how rocket engines work

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

"The Raptor is truly a GoldieLOX engine..."