How Much Delta V to Get to Jool
Okay, so this is going to be my first large-scale project in KSP. Also, my first manned mission to the Joolian system.
The plan is to make several passes at different altitudes to explore to planet itself, to crash a probe against it, to get science data from inside the atmosphere, to flyby all the moons, collecting science, and to land on Laythe, and the two smallest and outest moons on the system (Bop and Pol I believe they are called?).
Anyway, this is not gonna be a single mission, this is gonna be a series of missions, the last one will be the expedition to Jool itself. Its gonna require a lot of tests, a lot of preparations, because I don't know KSP as I know SFS, and there is technology that I need to unlock and to test for the Joolian project, and that is what I'm going to post on this thread.
So, the first preparation mission and I would say the easiest, is to test the Joolian impactors, the probes that are going to dive into the green's planet atmosphere to get science data from within. However we are not going to test them on Jool, because I don't think I'm ready to go there yet, we are going to test on the planet who's atmosphere is most similar to Jool's. We are going for Eve.
^There's the first rocket being launched.
I also forgot to say that we are going to launch two separate probes on two separate rockets, because we are not only testing the impactors, we plan to get some science from this mission to unlock more things on the tech tree. So, one probe will land on Eve's ocean, and the other one on Eve's surface.
The solar panels are immense, true. But remember, that this design is supposed to be for Jool, where there is not much solar power, and I haven't unlocked the RTGs yet. So, I brought these huge solar panels as well as 4 experimental fuel cells, that will power up the probe while falling into Jool's atmosphere. Here comes probe 2:
Yep, same rocket, same probe. Time for the transfer to the purple planet. Cruise stage separation!
Unit 1 arrives to Eve. It will try to land on Eve's ocean. I gotta say, I didn't even try to slow down, I went directly into the planet. I needed to make the most aggressive possible reentry because I'm simulating a Joolian reentry, which is going to be very extreme… extremely extreme 
…
Splashdown! Okay, the probe survided! I guess the landing legs were not really necessary, were they? Anyway, we are deploying the instruments, allow some Eve water to enter, so the instruments can test and perform some atmospheeeeeeeeeeeee…. WHAT ON EARTH DO YOU MEAN BY "UNABLE TO PERFORM ATMOSPHERIC SCAN RIGHT NOW"??? I STRUGGLED SO HARD TO BRING AN ATMOSPHERIC ANALYZER ALL THE WAY FROM KERBIN!!!
Anyway, apparently you can't perform atmospheric analysis from the water. We are not gonna get much science from this unit, guys . But, that's precisely why brought a second unit! That is precisely why I needed to do all these tests .
Unit number 2 needs to land on solid ground.
Yay! A successful landing! This time we managed to perform all the science experiment, including the atmospheric analysis and transmit all the data back to Kerbin!
Alright, that completes the first mission of the project, we already have some certified impactors that can resist a severe atmospheric reentry. We are definitively taking two of those to Jool.
How Much Delta V to Get to Jool
Source: https://jmnet.one/sfs/forum/index.php?threads%2Fksp-project-jool.6429%2F