I'm asking all these questions as one because I don't think they're worth cluttering the site separately for.

  1. How much does Raptor Boost weigh compared to normal Raptor?

  2. How much more thrust does Raptor Boost have than normal Raptor?

  3. What is the throttling capability of Raptor Boost compared with normal Raptor?

  4. Is the Raptor Boost significantly simpler than normal Raptor?

  • $\begingroup$ “Raptor Boost”? $\endgroup$ Apr 27 at 18:06
  • $\begingroup$ Some people seem to be calling the non-gimbaled Raptors on the SuperHeavy "R-Boost" as a reference to official designation"R-Vac" for the vacuum-optimized Raptors, but as far as I can tell that's just shorthand for "booster-raptors" and not an official term. $\endgroup$ Apr 27 at 18:50
  • $\begingroup$ @Abdullah I'm not sure where you're getting the information that there's a difference, though. As far as I know the only difference between the gimbaled and fixed engines is the gimbal. It's a little less weight and a little less complexity, but I don't see anything about the engines being stronger or throttling differently. $\endgroup$ Apr 27 at 18:52
  • $\begingroup$ IIRC, there was some mention a while back of plans for the fixed engines being a simplified version with higher thrust, but I'm pretty sure that was abandoned with them developing Raptor 2 instead. $\endgroup$ Apr 27 at 21:18
  • 2
    $\begingroup$ The Wikipedia article that says that Raptor Boost has higher thrust cites to an article that says it doesn't have higher thrust: "...the outer ring Raptor Boost (RB) being without Thrust Vector Control infrastructure compared to the Raptor Center (RC) of the middle and inner-ring, along with no differences in thrust between RB and RC variants as originally anticipated." $\endgroup$ Apr 28 at 1:17

1 Answer 1


So far as I can tell (though I've already been wrong about RB and RC today), the people who are classifying these are now doing so by their delivered configuration rather than obvious numbers painted on the engines themselves as in the past. The engines themselves are interchangeable between RB and RC as of Booster 7's flight, and indeed they have been so-changed:

See for example Raptor 93, described in the "SpaceX Raptor 1-100 tracker" (found from a tweet by SpaceRhin0 embedded in this NASASpaceflight.com forum post by robot_enthusiast) as

Was seen at the build site on [July 22 2022] as an RB, seen installed as an RC on B7 [Oct 10 2022]

The same forum post makes this claim:

The majority of engines are delivered in the configuration that they are intended to be used, but if plans change it doesn't appear overly difficult for them to make the switch. As far as I can tell, the only difference is the presence of the TVC arms and the assembly bolted to the top of the engine which interfaces with the vehicle. On an RC there are hinges in the top assembly and 100% of the plumbing is passed through. On an RB the assembly is a solid piece, and the plumbing for startup is routed to a panel on the side of the mounting bracket rather than being fed from the vehicle.

I chose that post because it's the most recent result in a Google search of NASASpaceflight.com for "Raptor Boost", from Oct 17 2022.

The usual disclaimer about these not being official sources but instead being a community drawing conclusions from the photographs they can take from outside the fence applies, but on an admittedly brief skim I believe that robot_enthusiast's post isn't controversial among those folks doing these observations and that the open-source intelligence work being done on that forum is grounded in physics and displays understanding.


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