The low pressure propellant ducts in SSME are routed around the engine in a somewhat complicated way. Both fuel and oxidizer lines leave the low-pressure turbopump, go around, down and then turn back to the high-presure turbopump. What is the reason for such contrived routing?
I can think of 2 possible reasons behind that:
- Length contraction due to temperature changes (both fuel and oxidizer are cryogenic).
- Flexibility: since the low-pressure turbopumps are fixed to the orbiter, but the rest of the engine is gimballing, the line must be flexible. This is solved by articulating joints on the tube.
Are there other reasons? Could these technical issues be resolved differently - for example using a wire braided flexible hose directly connecting both turbopumps? Although I am not sure if there is a material that is flexible at the temperature of liquid hydrogen.