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> do rocket engines also have injectors Yes[1]. You want the fuel and oxidizer mixed as well as possible to achieve efficient combustion. There are also other

> do rocket engines also have injectors Yes[1]. You want the fuel and oxidizer mixed as well as possible to achieve efficient combustion. There are also other small channels fuel has to flow through, like the ones used for regenerative cooling[2]. And not sure how well most turbopumps[3] would tolerate debris either, though that probably depends on the exact design. There are some really simple rocket designs out there that I could imagine tolerating debris (like solid motors[4] or pressure fed hyperbolic engines[5]) but Raptor definitely doesn't fall into those categories. [1]: https://en.wikipedia.org/wiki/Liquid-propellant_rocket#Injectors https://en.wikipedia.org/wiki/Liquid-propellant_rocket#Injec... [2]: https://en.wikipedia.org/wiki/Regenerative_cooling_(rocketry) https://en.wikipedia.org/wiki/Regenerative_cooling_(rocketry... [3]: https://en.wikipedia.org/wiki/Turbopump https://en.wikipedia.org/wiki/Turbopump [4]: https://en.wikipedia.org/wiki/Solid-propellant_rocket https://en.wikipedia.org/wiki/Solid-propellant_rocket [5]: https://en.wikipedia.org/wiki/Hypergolic_propellant#Characteristics https://en.wikipedia.org/wiki/Hypergolic_propellant#Characte...

s1artibartfast 3y ago
I posted upthread, but another concern is that stray particulate is an ignition source. Rocket fuel pumps are ~100,000 hp, and that energy is put into kinetic energy of the fluid flow. A stray particulate can cause the metal pump and fuel lines to burn in the presence of O2 at 300 atmospheres.
- foobarian 3y ago
  > Rocket fuel pumps are ~100,000 hp That is wild. I need to learn more about rocket fuel pumps :-) Thank you all for these comments.
  - s1artibartfast 3y ago
    They also arent as big as you might think. Much of the engine size you see in pictures is the Nozzle https://www.teslarati.com/wp-content/uploads/2018/08/Block-5-Merlin-1D-work-SpaceX-1-1-1024x569.jpg https://www.teslarati.com/wp-content/uploads/2018/08/Block-5...
  - ranger207 3y ago
    Fuel pumps are one of the most important design considerations of a rocket. When people talk about a rocket's specs, it's often going to be in the approximate order of thrust, efficiency (called ISP), fuel, and then what kind of fuel pump it has, aka its cycle https://everydayastronaut.com/rocket-engine-cycles/ https://everydayastronaut.com/rocket-engine-cycles/

s1artibartfast 3y ago

I posted upthread, but another concern is that stray particulate is an ignition source. Rocket fuel pumps are ~100,000 hp, and that energy is put into kinetic energy of the fluid flow. A stray particulate can cause the metal pump and fuel lines to burn in the presence of O2 at 300 atmospheres.

foobarian 3y ago
> Rocket fuel pumps are ~100,000 hp That is wild. I need to learn more about rocket fuel pumps :-) Thank you all for these comments.
- s1artibartfast 3y ago
  They also arent as big as you might think. Much of the engine size you see in pictures is the Nozzle https://www.teslarati.com/wp-content/uploads/2018/08/Block-5-Merlin-1D-work-SpaceX-1-1-1024x569.jpg https://www.teslarati.com/wp-content/uploads/2018/08/Block-5...
- ranger207 3y ago
  Fuel pumps are one of the most important design considerations of a rocket. When people talk about a rocket's specs, it's often going to be in the approximate order of thrust, efficiency (called ISP), fuel, and then what kind of fuel pump it has, aka its cycle https://everydayastronaut.com/rocket-engine-cycles/ https://everydayastronaut.com/rocket-engine-cycles/