by the way I'm working on a heavy lifting launch vehicle able to launch into sun orbit. I'm calling it the Detlas V. Here's the basics:
The first stage is powered by a Big Falcon Engine (I'm on PC, no biggie) and uses frontier engines on the boosters. The boosters are comprised of 2 large fuel tanks (I don't have giant fuel tanks, because PC isn't quite there yet :/).
The second stage a Big Falcon Engine like the first stage. It is fired twice: once to get it in earth orbit, and once for SOE (Solar orbit ejection).
The third stage gets it into Sun orbit, and is powered by a Frontier Engine. Once the spacecraft is in orbit, it does a pic burn, which basically slows it down the spacecraft's orbit so that the payload (usually a space telescope) can work properly.
That's the Detlas V in a nutshell.