I've been able to come up with a somewhat large-ish rocket that will deliver thrust up to 500K from the surface with a top speed of about 4000m/s. Due to the way the stages are set up its also perfect for getting into orbit. I've fiddled with several other types of designs since, but this seems to be the most stable/powerful combo I can come up with. Everything else I made so far always sacrificed one for the other. I present to you Freedom 7: The philosophy behind this craft is to have 1 stage at the top which will act as a retro-package to return to Kearth. The 3 fuel-tank stage beneath it is used to get the craft into orbit and trim said orbit. Everything below the first 2 stages has as only purpose to propel the upper 2 stages out of the atmosphere. Construction: Stage 00 Parachute Pod ------------- Stage 01 Decoupler ------------- Stage 02 SAS Fuel Tank LFE *Top Booster Package* ------------- Stage 03 Decoupler ------------- Stage 04 SAS Fuel Tank Fuel Tank Fuel Tank LFE ------------- Stage 05 Decoupler ------------- Stage 06 Tri-Coupler 3x SAS 3x Fuel Tank 3x Fuel Tank 3x Fuel Tank 3x LFE ------------- Stage 07 3x Decoupler *6x Radial Decoupler* ------------- Stage 08 *6x SRB* 3x SRB The *Top Booster Package* is mounted on top, but fired at life-off, so adjustments to staging are needed. I have however improved on this design by adding some more boosters to the life-off stage. The basic design & philosophy is the same, but the extra boosters provide a bit more oomph at lift-off and make sure that the bottom section of the craft is able to propel the final 2 stages all the way out of the atmosphere. The booster package accelerates the rocket to ~100m/s to an altitude of 6000m, after which the 3 remaining LFE's take over. They take the remaining rocket up to about 30-40.000m at ~450m/s This design requires even more fiddling with the staging though, but nothing too difficult I'd reckon. I also added 3 SAS to the booster section in order to compensate for a tendency to roll & bank. Freedom 7_Revision2: One note about both designs: due to the high COG caused by the boosters mounted at the top it is crucial to apply SAS as soon as the simulation starts in order to prevent the rocket from tumbling over on the launchpad. This high COG will also induced some movement, so it's important to wait for the pod to point straight up before launching, otherwise the rocket will take off at an angle. This is similar to the twang the Space Shuttle performs irl. It should also be mentioned that both rockets -though stable- have a slight tendency to roll left & bank right (at 90°) with the SAS turned off until the tri-coupler is jettisoned. The roll can be easily overcome by small control-inputs, as can the bank. Or if you do not correct the bank angle it will actually help pick up horizontal speed to make getting into orbit even easier.