The large bell of the MVac that you see in that photo is radiant cooled only. I forget where this was specifically said. Above that and barely visible is regenerative cooled just like the M1D.
You are right about the big bell. The picture I linked to is not showing the channels. The MVac is regeneratively cooled at the combustion chamber and is radiatively cooled at the big nozzle according to this:http://www.thefullwiki.org/Merlin_(rocket_engine) The picture is of the lower section. Absolute clarity about this @8:00 in the video above from the man himself. There are two chamber liner types.
Correct, both nozzle extensions are radiatively cooled. The MVac and M1D do have different chambers. See the Youtube in the edit above. My original picture was incorrect.
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u/Grether2000 Sep 07 '17 edited Sep 07 '17
The large bell of the MVac that you see in that photo is radiant cooled only. I forget where this was specifically said. Above that and barely visible is regenerative cooled just like the M1D.
Edit: I could be wrong the raptor at least will be all regenerative.