6 ms·

Question for the space nerds: how impressive is this?

by cgeier 3y ago

ericd 3y ago
According to the wikipedia article ( https://en.wikipedia.org/wiki/Prometheus_(rocket_engine) https://en.wikipedia.org/wiki/Prometheus_(rocket_engine) ), they're aiming for 3-5 reuses, which I believe is significantly fewer than SpaceX's Falcon 9 engine, Merlin. But maybe they'll get more in practice. It's a methalox/methane-oxygen engine, like SpaceX's Raptor, as opposed to RP-1 kerosene, like Merlin. One nice aspect of this is that methalox doesn't deposit so much soot on the inside of the engine, so reuse should be simpler (this is one of the reasons for SpaceX's newer Raptor engines also using methalox). It's got an open gas generator cycle, which means that it's likely less efficient than SpaceX's full-flow staged combustion Raptors, since it means it loses a few percent of its fuel to just running the turbopumps and the exhaust spitting off the side, rather than than heading down into the combustion chamber. It sounds like it's much cheaper to build vs. their last generation of engine, but we'll see how it ends up in practice. Getting something like this working is impressive, but who knows if it will end up being competitive, SpaceX is still iterating really quickly. Not an expert, but the design feels a little dated already, in comparison in comparison to Raptor, and Raptor is already flying.
- Diederich 3y ago
  > this is one of the reasons for SpaceX's newer Raptor engines also using kerosene Typo there :)
  - ericd 3y ago
    Oh good catch, thanks!
- deleted 3y ago
  [deleted]
frederikvs 3y ago
I'd say it's pretty impressive. Building and igniting a rocket engine is hard. For more detail, I can recommend watching "Why starting a rocket engine is so hard" by Tim Dodd [0]. It's not "never been done before" impressive, they're a few years behind e.g. SpaceX's Raptor engine, which uses the same propellants, and is also reusable. But still, a new rocket engine is no small feat - the engine is probably the hardest part of a rocket. This is quite literally rocket science. [0] https://www.youtube.com/watch?v=bAUVCn_jw5I https://www.youtube.com/watch?v=bAUVCn_jw5I
- chroma 3y ago
  They're more than a few years behind SpaceX. SpaceX reached a similar milestone back in 2016, when they test fired a subscale Raptor engine[1] that produced 1 meganewton (~100Tf) of thrust.[2] By 2019, they'd tested their full size Raptor at 1.5 meganewtons (172Tf) of thrust.[3] The current production version of Raptor produces 2 meganewtons (225Tf)[4]. SpaceX has successfully tested a newer version of Raptor that produced 2.4MN (269Tf) for 45 seconds.[5] 1. https://twitter.com/elonmusk/status/780275236922994688 https://twitter.com/elonmusk/status/780275236922994688 2. "With a thrust of 1MN (225klbf) at sea level, this was to be the first methane full flow engine to ever reach a test stand." https://www.nasaspaceflight.com/2016/10/its-propulsion-evolution-raptor-engine/ https://www.nasaspaceflight.com/2016/10/its-propulsion-evolu... 3. https://twitter.com/elonmusk/status/1093424663269523456 https://twitter.com/elonmusk/status/1093424663269523456 4. https://twitter.com/elonmusk/status/1295498964205068289 https://twitter.com/elonmusk/status/1295498964205068289 5. https://twitter.com/elonmusk/status/1657249739925258240 https://twitter.com/elonmusk/status/1657249739925258240
  - panick21_ 3y ago
    This European engine is comparable to Merlin, not Raptor.
breput 3y ago
Positives: * Uses liquid methane and oxygen for fuel, which is far easier to work with than the current Vulcain hydrogen/oxygen fueled engine and burns cleaner than kerosene/oxygen engines, which is better for reusability. * This is an engine that might work well on a small to medium reusable launcher, which ESA no longer has access to after their Vega rocket repeatedly failed and they lost access to Russia's Soyuz rockets[0]. * ESA is at least trying to do reusability after dismissing the idea for years. Negatives: * "100-tonne thrust class" is half the thrust of either SpaceX's Raptor or Blue Origin's BE-4 engines, which will be similarly reusable and using the same fuels. * Additive layer manufacturing sounds cool but I'm not sure it has any real benefits over conventional engine manufacturing techniques. SpaceX is reportedly close to building one Raptor engine _per day_ without 3D printing. * They are undecided on the fuel ("A version using liquid hydrogen-liquid oxygen is also being developed."). That is an entirely different engine and ground support infrastructure, but they are presumably doing it so it could be used directly in the Ariane 6 rocket? * Arianespace/ESA is at least a decade[1] behind SpaceX in reusability and due to rocket failures and retirements, and the delays with Ariane 6, won't have _any_ flying rockets until 2024. So they are far behind and do not have a good track record with speedy development. [0] https://spacenews.com/europe-grappling-with-space-access-challenges/ https://spacenews.com/europe-grappling-with-space-access-cha... [1] https://www.space.com/europe-no-reusable-rocket-until-2030s https://www.space.com/europe-no-reusable-rocket-until-2030s
- mezeek 3y ago
  Additive layer manufacturing has major benefits... unless you want to have a super-high production rate like Raptor. So it's a positive for them.
  - breput 3y ago
    I considered putting it as both a positive and negative, but I consider it overall a negative until the technology is proven to be as strong and reliable as traditional manufacturing techniques - not to mention faster and less expensive.
  - hutzlibu 3y ago

Question for the space nerds: how impressive is this?

by cgeier 3y ago

Question for the space nerds: how impressive is this?

According to the wikipedia article ( https://en.wikipedia.org/wiki/Prometheus_(rocket_engine) https://en.wikipedia.org/wiki/Prometheus_(rocket_engine) ), they're aiming for 3-5 reuses, which I believe is significantly fewer than SpaceX's Falcon 9 engine, Merlin. But maybe they'll get more in practice. It's a methalox/methane-oxygen engine, like SpaceX's Raptor, as opposed to RP-1 kerosene, like Merlin. One nice aspect of this is that methalox doesn't deposit so much soot on the inside of the engine, so reuse should be simpler (this is one of the reasons for SpaceX's newer Raptor engines also using methalox). It's got an open gas generator cycle, which means that it's likely less efficient than SpaceX's full-flow staged combustion Raptors, since it means it loses a few percent of its fuel to just running the turbopumps and the exhaust spitting off the side, rather than than heading down into the combustion chamber. It sounds like it's much cheaper to build vs. their last generation of engine, but we'll see how it ends up in practice. Getting something like this working is impressive, but who knows if it will end up being competitive, SpaceX is still iterating really quickly. Not an expert, but the design feels a little dated already, in comparison in comparison to Raptor, and Raptor is already flying.

Diederich 3y ago
> this is one of the reasons for SpaceX's newer Raptor engines also using kerosene Typo there :)
- ericd 3y ago
  Oh good catch, thanks!
deleted 3y ago
[deleted]

frederikvs 3y ago

I'd say it's pretty impressive. Building and igniting a rocket engine is hard. For more detail, I can recommend watching "Why starting a rocket engine is so hard" by Tim Dodd [0]. It's not "never been done before" impressive, they're a few years behind e.g. SpaceX's Raptor engine, which uses the same propellants, and is also reusable. But still, a new rocket engine is no small feat - the engine is probably the hardest part of a rocket. This is quite literally rocket science. [0] https://www.youtube.com/watch?v=bAUVCn_jw5I https://www.youtube.com/watch?v=bAUVCn_jw5I

chroma 3y ago
They're more than a few years behind SpaceX. SpaceX reached a similar milestone back in 2016, when they test fired a subscale Raptor engine[1] that produced 1 meganewton (~100Tf) of thrust.[2] By 2019, they'd tested their full size Raptor at 1.5 meganewtons (172Tf) of thrust.[3] The current production version of Raptor produces 2 meganewtons (225Tf)[4]. SpaceX has successfully tested a newer version of Raptor that produced 2.4MN (269Tf) for 45 seconds.[5] 1. https://twitter.com/elonmusk/status/780275236922994688 https://twitter.com/elonmusk/status/780275236922994688 2. "With a thrust of 1MN (225klbf) at sea level, this was to be the first methane full flow engine to ever reach a test stand." https://www.nasaspaceflight.com/2016/10/its-propulsion-evolution-raptor-engine/ https://www.nasaspaceflight.com/2016/10/its-propulsion-evolu... 3. https://twitter.com/elonmusk/status/1093424663269523456 https://twitter.com/elonmusk/status/1093424663269523456 4. https://twitter.com/elonmusk/status/1295498964205068289 https://twitter.com/elonmusk/status/1295498964205068289 5. https://twitter.com/elonmusk/status/1657249739925258240 https://twitter.com/elonmusk/status/1657249739925258240
- panick21_ 3y ago
  This European engine is comparable to Merlin, not Raptor.

breput 3y ago

Positives: * Uses liquid methane and oxygen for fuel, which is far easier to work with than the current Vulcain hydrogen/oxygen fueled engine and burns cleaner than kerosene/oxygen engines, which is better for reusability. * This is an engine that might work well on a small to medium reusable launcher, which ESA no longer has access to after their Vega rocket repeatedly failed and they lost access to Russia's Soyuz rockets[0]. * ESA is at least trying to do reusability after dismissing the idea for years. Negatives: * "100-tonne thrust class" is half the thrust of either SpaceX's Raptor or Blue Origin's BE-4 engines, which will be similarly reusable and using the same fuels. * Additive layer manufacturing sounds cool but I'm not sure it has any real benefits over conventional engine manufacturing techniques. SpaceX is reportedly close to building one Raptor engine _per day_ without 3D printing. * They are undecided on the fuel ("A version using liquid hydrogen-liquid oxygen is also being developed."). That is an entirely different engine and ground support infrastructure, but they are presumably doing it so it could be used directly in the Ariane 6 rocket? * Arianespace/ESA is at least a decade[1] behind SpaceX in reusability and due to rocket failures and retirements, and the delays with Ariane 6, won't have _any_ flying rockets until 2024. So they are far behind and do not have a good track record with speedy development. [0] https://spacenews.com/europe-grappling-with-space-access-challenges/ https://spacenews.com/europe-grappling-with-space-access-cha... [1] https://www.space.com/europe-no-reusable-rocket-until-2030s https://www.space.com/europe-no-reusable-rocket-until-2030s

mezeek 3y ago
Additive layer manufacturing has major benefits... unless you want to have a super-high production rate like Raptor. So it's a positive for them.
- breput 3y ago
  I considered putting it as both a positive and negative, but I consider it overall a negative until the technology is proven to be as strong and reliable as traditional manufacturing techniques - not to mention faster and less expensive.
- hutzlibu 3y ago