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"Mr. Musk has since confirmed that the development engine will eventually have a nozzle with an expansion ratio of 150, the maximum possible within Earth’s atmosphere."
In other words, to beat Merlin in TWR Raptor would have to be less than 1690kg.
Also, this makes the thing more intriguing. It might be a big coincidence, but a 1MN dev model with a nozzle area ratio of 150:1 might be very close/exactly what is needed for a Falcon9/FH Mvac methalox replacement. Which is what incidentally the USAF paid for when entering a contract with SpaceX for this. Too many coincidences?...XD
That was an excellent article, that even a novice like myself could follow... one question popped up: will the Raptor be more difficult to mass produce than the present Merlin engines? Thanks... Gramps...
An impressive article. I did not realize the engine Musk showed on the video was a 1/3 full scale unit. The real surprise is the speed with which this engine has been built given the very limited prior art in the West on such designs. IIRC Aerojet regularly put them into their design proposals but I don't know if many (any?) of them got to development I would guess they studied the SSME development history very carefully and started trying to take the engine through simulated start ups and downs much earlier in the timeline than the SSME developers were able.
The real surprise is the speed with which this engine has been built given the very limited prior art in the West on such designs. IIRC Aerojet regularly put them into their design proposals but I don't know if many (any?) of them got to development I would guess they studied the SSME development history very carefully and started trying to take the engine through simulated start ups and downs much earlier in the timeline than the SSME developers were able. An interesting question would be wheather SX were able to avoid putting an oxidation resistant coating on the O2 rich pre burner turbine blades. IIRC the Russians could not quite guarantee the blades would survive without it and it's one of the issues that have made making the RD180 in the US difficult. For a single use engine this is not an issue but for a reusable engine it becomes a critical inspection issue. SSME had it with their gold plating of the turbine blades to resist attack by the high temperature GH2/Steam stream from the pre burners. Fortunately Methane is not Hydrogen so a resistant alloy should be possible but time will tell how robust the engine is. For those worried about the size of the SL nozzle keep in mind how much above the SSME main chamber pressure Raptor is.
The only question I have from that article concerns the use of heat exchangers. I always thought that you could tap the methane for pressurization right after it exits the regenerative channels and not need an additional heat exchanger for that. Do we know that the methane channel will indeed use an exchanger?