This is by far the steadiest and most reliable design for a heavy lift I have gotten so far. The first one I am ready to share. I am currently working on a version of this design that will double the payload put into orbit with some success. Will post it here when i get it to the reliability of the Mk.1 And here she is... First stage is 12 LFEs fed by two tanks each, with an additional 8 SRBs for initial liftoff. After SRBs burn out you will lose about 10m/s velocity before it will begin to accelerate again. First stage burns out at 15km with a speed ~250m/s. Full throttle all the way. Second stage is 4 LFEs fed by 3 tanks each. Until a reliable retro is developed a few seconds will have to be given before igniting second stage or explosions result. I find slowing to around 190m/s gives enough distance without the losing to much. After ignition maintain vertical flight to around 25km before rolling to horizontal, lock STS to about 20 degrees above horizon and continue burn through till tanks are empty. Throttle may have to be adjusted a little as the tanks empty to keep it steady. Second stage should burn out with a velocity just under orbit speed. Third stage is an orbital maneuvering stage. With very little fuel needed from this stage to level out initial orbit you have nearly 3 full tanks to do any orbital testing. This is more than enough to do several transfers and have also used my preliminary design of this craft to reach escape velocity and a distance of 32000K before returning. The Sol Mk. 1 is the result of these missions. Final stage is for re-entry with more then enough fuel for several orbital adjustments to bring the CnC module home safely should anything bad happen to the orbital stage. (Like accidentally clicking spacebar instead of ctrl at 500km up. >.< ) Design uses all stock engines, fuel tanks, and SRBs. 2 Add-on couplers where used.. The Lateral Couplers from Sunday Punchs Wobbly rocket pack: http://kerbalspaceprogram.com/forum/index.php?topic=79.0 The Red Stripes Advanced Decoupler(only cause I hadn't seen the yellow one yet.) From Quabit: http://kerbalspaceprogram.com/forum/index.php?topic=537.0 Edit: after going over to make sure I didn't miss anything.. I found that I did. >.< You will also need Quadbits original sheath decouplers found in this link: http://dl.dropbox.com/u/6228295/quabits_ksp_parts.zip