> Spacex only very recently got their closed cycle engine working, the pinnacle of rocket efficiency, catching up to, again, early 1970s Russian technology.
The Raptor is the first functional full-flow staged-combustion methalox engine, and it's already been successfully fired. By some measures, that surpasses both Soyuz technology and the RS-25. Of course, we have yet to see what their true Isp and T/M numbers will turn out to be, but they do plan to use multi-stage (including a refuel in LEO) with separately tuned engines on each. The overall performance (i.e. tons to Moon and beyond) will be very interesting to see.
The Raptor is the first functional full-flow staged-combustion methalox engine, and it's already been successfully fired. By some measures, that surpasses both Soyuz technology and the RS-25. Of course, we have yet to see what their true Isp and T/M numbers will turn out to be, but they do plan to use multi-stage (including a refuel in LEO) with separately tuned engines on each. The overall performance (i.e. tons to Moon and beyond) will be very interesting to see.