Why don't rocket engines melt? How engineers keep engines cool

Rocket engines need to produce heat to function, after all, their only real purpose is to convert the chemical energy in the propellant into pressure and heat so they can produce thrust.

And that brings up an obvious question! How in the heck do engines survive this heat? How did rocket scientists figure out how to keep an engine running continuously while harboring combustion inside it that’s hot enough to melt the very walls that are containing it?!

Today we’re going to talk about the tricks engineers employ to keep rocket engines from melting. We’ll go over ablative cooling, regenerative cooling, film cooling, radiative cooling, heat sinks, and fuel to oxidizer ratios and show you some awesome examples of each.

00:00 - Intro / Timestamps
01:55 - Heatsink
04:12 - Fuel to Oxidizer Ratio
07:20 - Ablative Cooling
10:30 - Regenerative Cooling
14:20 - Film Cooling
22:15 - Radiative Cooling
23:30 - Summary

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[taketh]

During the Apollo program, when I was about 13 (1970), I was curious about rockets. I went to the library and found two books on rockets. I remember reading about regenerative cooling, and a light went off in my head as I was provided the answer to such a difficult problem in two seconds. The problem seemed exotic and insurmountable, yet it was ‘handled’ with a simple and elegant solution. I went on to become a structural design engineer from that initial effort. Hope you reach 10, 000 such young men and women.

[CorrectiveAction]

Literally since I was a kid, I was curious about that dark section of the F1 exhaust. I'm 55 now, and this is the first time I've had it explained to me. Thanks so much Tim, and thanks for all your work.

[franksmith]

Watching your video, “Why Rocket Engines Don’t Melt”, with my grandson, who is a student at CalPoly studying to be electrical engineer, he said, “grampa, Tim should be an engineering teacher at CalPoly. Tim explains information not only very clearly and understandable, but speaks in a pleasant and comfortable manner that makes his presentation interesting”. Thank you Tim for providing your time and energy to help educate the public. You should feel good and proud of yourself.

[charlesvandeweghe]

Very educational. I love how Tim makes very complex concepts fairly easy to understand. His illustrations really help. Nice job Tim!

[StanleyCreative]

Very fun to work on this one, I hope everyone liked the animations! 🔥❄🚀

[harmonyspaceagency]

The idea of keeping super cool and super hot things so close together is crazy to think.

[savannahwhite]

Hey Tim, I find myself very fascinated and as of lately, pretty passionate about learning about rockets. I haven’t yet found any other videos as helpful or easy to understand as yours. Thanks for really bringing space down to earth for everyday people like me! 👍🏼 Your channel is a huge part of my growth in knowledge on space exploration and I’m so grateful for that!

[KonJonnorMusic]

This is easily one of the best videos I've ever seen on YouTube. When you said "this is rocket science", it blew my mind that you were presenting the information in such an easily accesible way. Instant subscribe.

[weeblewonder]

These transitions are like next level. The writing and structure of this video is like A++. Well done to the team.

[yukionna]

Jet turbine maintenance engineer here, we use most of these same methods to prevent aircraft engines eating themselves. Primarily film cooling though. Most engines tap off high pressure bleed air from the final stage of the compressor (which is already at around 300°c or more to cool the hot parts of the engines. Effectively in a turbine engine the combustion gases will NEVER actually contact any of the metal parts as they'd simply burn through it in seconds.

Most impressive one being that the turbine blades are grown from a single crystal of titanium, are hollow to utilise the regenerative cooling via channels inside and then vent those hot gasses via tiny holes in the surface to maintain a film of gas in between the blade itself and the combustion gases, all while spinning hundreds of times a second

[matthewnelson]

Thank you! I’ve wondered my whole life why the Saturn V engines had that top section of black exhaust. I’ve searched and this is the first time it was explained.

[Xcelential]

Fantastically informative. I loved the graphics explaining the principles, combined with close-ups of actual engines employing those principles. Great job!

[giacomoscomparin]

Just amazing. I'm an aerospace engineering student and I learned so much from this video, especially through the examples from history and the amazing animations, thanks Tim! One of my favorites for sure. Besides I'm studying applied thermodynamics at the moment so the timing is also spot on!

[valerieyearsago]

One of the few channels I don’t hesitate to click on. Thank you for the hard work Tim, you truly inspired me to get into the nitty gritty of rocket science.

[justNU]

I'm not going to remember any of this but this is really interesting.

[johnvajcner]

As a retired metallurgical engineer I always wondered how they cooled the wonderful metals on the engines knowing that they should melt quickly. Very well explained sir. Thank you! Of course we used carbon block refractory in the cupolas for melting grey iron to cast engine blocks and heads, etc

[alexanderwermlund]

One thing amaze me about rocket engines is that there are drive shafts between the turbines that mechanically transfers momentum to drive the propellants against the high pressures in the combustion chamber.
It's not only pipes but also mechanics.

[jasonmcgee]

*Refreshing subfeed to check for transporter3 livestream and this pops up. Transporter3 can wait.

[thunderamu]

This video is so well put together that it could be used at a Technical School. Well done Tim!

[agi]

This is the first rocket science video I watched on YouTube as there are not much videos on this topic and you didn't disappointed us thanks for the informative video.