I am trying to model the Merlin 1D+ using inventor. I was wondering what the major differences between the Merlin 1D and 1D+ were. I find when I search trying to find a 1D+ engine all I come across is 1D.
Also, I know the basic parts of a rocket engine and I know the Merlin is a gas generator cycle. However, I am wondering if the heat exchanger on the nozzle is for heating the helium and cooling the nozzle or heating the LOX while still cooling the nozzle?