SpaceX Ship 30 Static Fire | 7 Minute Super Slow Mo 

Could have been anyone. He didn’t say a word.

Yes, it is the best static buyer video because it’s from the new static fire test stand.

*hot

On the old sub orbital test stands they always started the center Raptors first but this way do the test stand being so low to the ground. In flight the vacuum Raptors ignite first and the increased height of this new test stand allows them to do a flight like ignition sequence.

@@RyanHansenSpace What is the orange colored flames? There seem to be three main ones and the one in the center looks like something is leaking. I wish they had shown the shutdown sequence.

If you see the hot staging ring inside you will note that the center engine's bell are fully covered by a inferior dome, and vacuum raptors are free to do the hot staging. Than, after some seconds of the hot staging, the center raptors are not more covered and can be ignited.

@@59seank they use a fuel rich mixture to do film cooling so the engine bells don't melt, you can clearly see the middle of the mach diamond being bright blue while the exterior is all orange that is because in the middle they use a more balanced fuel ratio while on the outside they use fuel rich so the hot oxygen won't eat away the engine, as for the middle raptors I guess they don't have a big enough engine bell so the film cooling mixes with the good mix and in the end is just all orange.

@@witgangyounotube287 Thanks for the explanation.

Don't forget when he filmed the astroid impact on the dinosaurs.

It's called "sublimation." But I don't know where in that video where that is taking place. The "chunks" you see flowing in are water ice and that doesn't sublimate in Earth atmosphere. However it will sublimate on the surface of Mars.

Working on a deep dive now. Should be worth the wait

Always is😊

@@CSIStarbase It very much was

don't think it's static when they fly off the test stand

Or they could just do it themselves

But one day, literally.

Why would they do that? They obviously have the gear to do it themselves and a way bigger budget than Slow Mo Guys could ever dream of.

Or a collaboration dream team, Adam savage, slomo guys, and smarter everyday.

Explain exactly what u mean by “belt out the exhaust gases way faster”? Does that mean the exhaust gas velocity is faster or that the startup sequence appears to be faster to attain steady state?

@@Mentaculus42 Yes, I meant exhaust velocity primarily, but it indeed also pertains to the startup sequence control.

The exhaust velocity for these engines is lower than the exhaust velocity of the space shuttle main engines at sea level.

@@ryanspence5831 Yes, that is correct. Hence my question.

That's what I was thinking. I'm like, SpaceX is ramping up for IFT-5 launch soon, so CSI Starbase has got to be dropping a deep dive video right before. My guess is the video is going to be about the tower catch attempt, but knowing Zack, he'll do something completely random and unexpected like how humidity affects engine relights or something crazy.

@@vmcprojects IIRC, he mentioned doing a deep dive on the flame trench. But a tower catch deep dive would be EPIC!

You can see the ring of flow separation from 0:22, then on 0:39 he goes outside the engine bell, than on 0:57 it becomes a kind of turbulent mach diamond and the plume stays a little less unstable. This if why the engine bell have a stability band around the final portion.

That would be significantly more difficult due to the amount of gas that needs to be smoothly directed away without turbulence and backflow. The plate already redirects the gas pretty well, if the booster was held higher up from the mount hole, and the hole was larger, you'd be able to place a camera pointing upskirt without fire or vapor flying everywhere. The the SLS for example, a camera inside the trench wouldn't get any good footage once the water is on and the engines ignite. So whether it's a more mono directional flame diverter like this vs the plate, they need the booster higher off the opening below for a clean view.

Astonishing how hard it is to lock down camera motion amid the rocket inferno.

The latter two engines are twice the size and produce less thrust!

Next episode coming soon

@@CSIStarbase im going to take a wild guess, it's going to be about the chopsticks. Can't wait!

Still not stabilized and still early ignition, the engines use film cooling to protect the combustion chamber, so expect orange around the edges always and expect fluctuation of that when it's barely just ignited. You can see how over time the exhaust clears up and becomes more transparent, that's the engines stabilizing turbo pump control and then most likely adjusting the fuel ratio to be more balanced and less rich. Since there's 2 independent turbo pumps not connected by a shaft, oxygen and methane can be throttled individually to change the fuel ratio. On startup the safe thing to do is keep the methane turbo pump a decent margin ahead of the oxygen pump and keep things rich until things are up to speed and predictable. On shutdown I would assume it's similar, cut oxygen speed first and keep it rich on shutdown to avoid damage to the combustion chamber.

R-vac has a low expansion ratio preventing flow separation--I think it's about 70:1

@@ryanspence5831 80:1, and there is some flow separation during startup.

One reason is the film cooling used for the combustion chamber, that's highly rich methane that will burn orange around the edges of the exhaust. The other is that on startup things aren't going to be as clean as stable operation, this is only a few seconds stretched to over 7 minutes, even 1 minute of this is less than 1 second of real time. It looks like they start fuel rich and lean out later, we see this on shutdown too where it gets much more orange the last second or two before the engines are off. The third reason is that their static fires I believe are only at 50% which is the minimum throttle range. The combustion may not be as complete at the minimum of their operating range, it may not mix as much with the lower flow rate into the combustion chamber. Especially during startup before reaching a stable 50% I would assume the mixing of methane and oxygen is very uneven before exiting the combustion chamber and you'll see streaks and pockets of orange.