> What's is level of complexity relative to something like V2 rocket engine that was suppose to be scaled for 2000 per month. Historically, von Braun had to us

> What's is level of complexity relative to something like V2 rocket engine that was suppose to be scaled for 2000 per month. Historically, von Braun had to use 70% ethanol - i.e., diluted with water - to avoid V2 engines burning through. So, loss of efficiency. It took quite some efforts to e.g. Glushko with Liliput to switch to kerosene (and cylindrical chamber and flat injector head) - the result was R-7 engines. Some decades of improvements - for example, V2 uses hydrogen peroxide to drive turbopumps, modern engines all use main components, which at least simplifies the engine overall, the closed cycles don't have separate exhaust after turbine, turbopumps are much more efficient (geometry in 1940-s wasn't too good from fluid dynamic point of view, turbine vanes didn't use that high temperature gas, losing in efficiency - here some material development work is important), and others. Raptor has an order of magnitude higher thrust. A lot more complexity, I'd say.