Article on the Raptor Vacuum version. SpaceX's Starship Raptor Vacuum engine plans laid out by CEO Elon Musk
Sorry, if was covered somewhere else.. Did we ever get confirmation of the last hop test engine coloration change? If that's an issue, it makes me nervous for the next test, with the duration being much, much longer.
Awesome video on engine injectors. The Raptor is the last to be talked about. https://www.youtube.com/watch?v=aa4ATJGRqA0
Wonder if Elon’s tweet about them extending Super Heavy an extra 2 meters means they are getting higher performance than expected out of the Raptor.
Or maybe after switching Startship from carbon fiber to stainless steel Elon realized that the new design was so much heavier than before that extra propellant would be needed to get it to orbit.
Without context both are plausible, with the latter more likely. One could imagine better-than-expected performance being realized as the ability to stuff more payload mass in starship rather than stuffing more propellant on the sub orbital stage. A few other plausible drivers could be: —re-entry stability —some weird harmonic —more volumetric configurations at the top or the bottom (for perhaps additional thermal mitigation, plumbing, ease of manufacturing/refurbishment, better/easier starship integration)
Cool that Tory and Peter chimed in. (Elon needs to put the twitters down in general so I don't support his otherwise helpful response. )
Wow; ask an interesting rocket question and get responses from actual experts. I guess Twitter is good for something...
I can see some minor differences between those engines (in the complex plumbing and visible hardware) but have no idea why that would be the case. I understand the basics of why the vacuum bell is so much larger, but that’s about it.
Differences are minor because this is a test engine; practically just same raptor with bigger nozzle, example flexible joint is still there. Vacuum-Merlin and sea level- one are almost different engines; same can be true with raptor too, when vac. version evolves. Tweets: Elon: Worth noting that thrust is only slightly higher with the big bell nozzle version. Larger bell is primarily for efficiency in vacuum. Aiming for 380+ sec Isp for RVac long-term. Initially likely to be ~372. @PPathole: Elon, are those hinges required for thrust vectoring at the very top? Will those be used for mounting on the test stand? Elon: This is a test engine. Flight articles are fixed with no gimbal. @Erdayastronaut: Odds of it surviving its first test? Pretty confident it'll work perfectly or is the first run of a new nozzle design pretty risky with a low chance of success? Elon: Above 50% likely to make it https://twitter.com/elonmusk/status/1302069036621033472
Raptor Vacuum full duration test: https://twitter.com/spacex/status/1309317126130339845?s=21&fbclid=IwAR3mUsblSdw0Gv0CRFrl3WIE9WYdKT7kYcY_iWee-2A50C_HDUS2aCf1VhM
Basically a marginally-controlled directional explosion. Freaking amazing to watch. Wonder what the dB sound pressure is like just there!?