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Quote from: livingjw on 11/25/2017 04:40 pmI'm just saying that I have seen no evidence that the Raptor or Merlin use any type of spin up system. Does anyone know different?Merlin uses a spin up system driven by high-pressure helium. The actual valves used to control the flow of fuel and LOX are spring-actuated (built into the pintle in the case of the combustion chamber, not sure about the preburner but presumably it has something similar?), so in order for fuel to even be injected the pressure must be high enough, which requires first spinning up the turbopump somehow.
I'm just saying that I have seen no evidence that the Raptor or Merlin use any type of spin up system. Does anyone know different?
Any new information from SpaceX on Raptor development?
It appears the Raptor is still the only FFSC engine currently under development. It has been shown to work at full thrust for many minutes in sub-scale form. Why are other space agencies not pursuing this very efficient technology? Why aren't Russia, China, India and the ESA pursuing Methane as the fuel of the future? It seems Blue is going for a slightly more proven ORSC methalox design, and is slowly making some progress, but even that seems years ahead of any new motor on the horizon.
It appears the Raptor is still the only FFSC engine currently under development. It has been shown to work at full thrust for many minutes in sub-scale form. Why are other space agencies not pursuing this very efficient technology?
Why aren't Russia, China, India and the ESA pursuing Methane as the fuel of the future?
And methalox is not an optimal booster propellant. Kerolox allows lighter tanks, and for similar engine, allows better T/W.
>BUT... can't make propane on mars...
Somewhere (can't find it now) I saw a paper by someone in the EU rocket group, that sub cooled Propane and sub cooled LOX actually works out as the best mass fraction (tank sizes, weights etc) propellant to use in a booster stage... BUT... can't make propane on mars...
Quote from: John Alan on 01/30/2018 06:27 pm>BUT... can't make propane on mars... Sez here you can, using Fischer-Tropsch Synthesis.https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140002709.pdf