Changes made

BTW, the TweakScale stuff for the engine parts is not required anymore, as we have a global patch to take care of that: https://github.com/KSP-RO/RealismOverhaul/blob/master/GameData/RealismOverhaul/RO_Engines.cfg#L17-L25

Acknowledged, removed it to ensure there was no interference with the global patch.

Thank you for pointing that out.

Well, now that I know that engine configs are a thing, would it be a good idea for me to add the HG-3 and HG-3-SL to the J-2 series engine configs? The HG-3 and HG-3-SL were derived from the J-2, and have higher performance.

Created HG-3 engine and HG-3 Config.

Would it make sense to give the upper stage variant extra ignitions? considering it was considered for use on the Saturn MLV's modified S-IVB stage.

Alright, so that should fix the Test Flight thing. Also, added a temporary Real Plume config courtesy of Cosmonaut Crash on YouTube. I'll just get this all compiled and off to him for more testing prior to an official merging of this pull request.

@PhineasFreak is this good now? It has a plume config (albeit not necessarily the most fitting one for the vacuum variant), and the TestFlight stuff should be working.

@Ash19256 the ModuleEnginesRF fields are not needed anymore (they are patched automatically) but otherwise it is good!

Fixed that. Looks like this is ready for merging otherwise.

Does this already config the SHIP version? https://github.com/Saabstory88/RO_Extended

Uh.. no. I'll get on that right away.

Right, that should add SHIP compatibility to this pull request. I'll see what I can do about testing it, but otherwise it should be fine.
EDIT: @PhineasFreak that's pretty much what I did, actually.

@Ash19256 disregard my initial comment, it did not work as i expected to. I was talking about these two lines:

https://github.com/Ash19256/RealismOverhaul/blob/42907f86c9535468f44278523bf085c789f373d5/GameData/RealismOverhaul/RO_SuggestedMods/SHIP/Engines.cfg#L18-L19

Oh, okay. I wasn't sure which lines you were talking about. Those are still in the SHIP/Engines.cfg file.

Yea, it was a bit of a brainfart...

Out of curiosity, is there a tutorial or something for making a RP-0 PR for something like this? Is it something that I should only do after this PR gets approved/merged or what? Also, is there a How To guide type thing someone could link me to if it's okay to make a pull request to add this into the RP-0 tech tree at this time?

EDIT: Or is the fact that RP-0 flags them as "Non RP-0" a fail on my part, because the configs are missing something that they should have?

RP-0 needs to be made aware, yeah--best bet is to talk to @pap1723 about how to integrate them into the new tree, since the methodology has changed significantly from the current release build's way.

So should I just wait for @pap1723 to make an appearance?

I have appeared!

@Ash19256 What that means is that the parts were not priced and place on the Tech Tree. So RP-0 will automatically flag them as Non-RP0. Do you have real-world pricing on these parts?

@pap1723 Unfortunately no, I've only been able to find 3 sources, none of which list a unit cost. Considering the HG-3 and it's seal level variant were never actually built IRL (it was, as far as the sources I've found have indicated, an on-paper project only, with no prototypes built), that's not really surprising. Considering the time period and other engines available at the time, I'd imagine that it'd be probably somewhere in the same price range (probably around 5-10% more expensive) than the J-2S, which my sources indicate it's a contemporary of. Take into account the higher chamber pressure making manufacturing more expensive, and making it cost more than the roughly similarly sized J-2S makes sense to me. But ultimately, the price would be a best guesstimate, simply because no IRL price for the engines can be found.

If memory serves the HG-3 was, like, halfway between J-2 and RS-25*, so I'd suggest a price somewhere between them rather than so close to J-2, maybe?

*RS-25 was developed using a lot of the techniques used for HG-3, IIRC.

Yeah, that sounds vaguely right. Although, based on it's capabilities, I'd lean more towards the J-2 side of things than the RS-25 side of things, mostly because the engine only produces around 27% more thrust for the same fuel consumption. That being said, it's ultimately up to @pap1723 and the others, so I'll go along with whatever they decide the price should be. I'll just need to know what to change in the configs to make them not get flagged as non RP-0.

Right, with this recent update this PR should be compatible with the SHIP mod. All that's needed now is to figure out RP-0 compatibility.

Great! RP-0 stuff is done on RP-0 side so that's all set! :)