Ok that is a very funny XKCD.

​Flight 5 is coming soon.

The video they released of flight 4, looked like a CGI. But was real. The way the flap got eaten away by the hypersonic air flow, wow...

@geoffc - Yes, I catch myself getting confused between real and virtual as well. We are adjusting to new visual sensations created by Elon Musk.

@Vorac the fire doesn’t cool it, but the propellants are often piped through tiny tubes or channels within the bell of the engine, then into the combustion chamber. You can see a similar effect by boiling water in a plastic bag - not exactly the safest thing, but the water can manage to keep the bag below its melting point. If something goes wrong though, the bag can melt, just like a rocket can melt if the cooling fails

@fyrepenguin ahahha, I've done that in my youth - boil a bottle of Coca Cola over open flames for nearly half an hour. It didn't melt.

But Your comment answers one of my questions and I am grateful for that!

@Vorac one example to look at is the RS-25 en.wikipedia.org/wiki/RS-25 since there are a lot of good photos and documentation of that engine

@Vorac what’s the melting point of a coke bottle, vs the temperature of a campfire?

@TheMatrixEquation-balance I still cannot get over wathcing the fins heat up the plasma forms and backs off the tiles. Like a CFD class in real life.

Kind of makes you wonder why SpaceX does not bid on some of the hypersonic weapon programs. They clearly have more hypersonic flight data than anyone else on the planet.