I came across a meme depicting a supposedly oxygen rich, fuel rich, and "engine rich" cycle of rocket engine. However, I'm pretty sure at least one of them is incorrect listing what looks a lot like an RS-25 as "oxygen rich". I'm curious if the the other one there is correct, specifically the "Fuel Rich" one, but I couldn't figure out which type of engine it is. I've cropped just the photo to the engine of interest here:

Rocket engine firing vertically with orange-purple exhaust

Can anyone identify which engine this is? At a minimum, we can rule out anything that's come out in the last 3 years

  • 1
    $\begingroup$ I ended up figuring this out purely by chance. After writing up my question (already having tried and failed to search), I threw the cropped image into Google's image search tool, and it immediately came up. I'm not sure why I didn't think of trying that earlier. $\endgroup$ Commented Mar 21 at 3:14
  • $\begingroup$ Makes sense that an image source would find it, those black panels on the nozzle are pretty unique. $\endgroup$ Commented Mar 21 at 11:29
  • 1
    $\begingroup$ @OrganicMarble yeah, I just wasn’t expecting success, since I usually only expect to be able to search for an exact match, rather than the original from a cropped or altered image. $\endgroup$ Commented Mar 21 at 17:10

1 Answer 1


It turns out that this is a RS-68 engine, which is a hydrolox gas-generator cycle. I think it's a fuel-rich preburner gas-generator, at least. But it's at least not a form of staged combustion cycle like the other two from the meme.

full photo of RS-68 engine from Wikipedia, from which the photo in the question was cropped

Found here: https://commons.wikimedia.org/wiki/File:RS-68_rocket_engine_test.jpg


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.