The Space Shuttle Main Engine low pressure pumps to prevent cavitation at the main pumps. This pumps were driven by separate turbines fed by high pressure fluid from the main pumps. Why? It just adds additional ducting complexity. Why couldn't they also be driven by low RPM turbines on the concentric shafts with the main pumps, powered by the preburners, similar to how jet engines work?

  • $\begingroup$ (wild guess) Possibly it's desirable to control their power individually? $\endgroup$ May 15, 2023 at 7:14
  • $\begingroup$ @OrganicMarble or you could just add another turbine like virtually everyone else... $\endgroup$ May 16, 2023 at 13:45
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    $\begingroup$ Yeah, your "the same shaft" fooled me, because it's incorrect. Jet engines have concentric spools/shafts rotating at different speeds. Is that what you are proposing? $\endgroup$ May 16, 2023 at 13:46
  • $\begingroup$ @OrganicMarble yes, correct. Sorry for that cinfusion $\endgroup$ May 16, 2023 at 13:50
  • $\begingroup$ Anyway, the low pressure pumps were mounted on the vehicle - they didn't even gimbal. It would have been impossible/impractical to physically connect them with a shaft to the high pressure turbines. You might be able to make a design like you propose, but it would be a completely different engine. space.stackexchange.com/q/35995/6944 $\endgroup$ May 16, 2023 at 13:51


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