My ship just explodes at 6100m.

[SRV Ron]

Maybe you were accelerating to fast, did you try throttling down? That has happened to me, I just didn't notice until I saw the g-force meter needle was as high as it could go.

The arc over picture was a problem with insufficient bracing. When I didn't have braces across the decouplers for those huge SRBs, they flew apart on launch. Properly braced, the flight was flawless with no spin or pitch issues.

Did something else last night but here are two shots of the Jool mission.

The mothership after aerobraking;

The resulting orbit.

Orbit has been tweaked to avoid crashing into Jool.

After doing the probe missions, I will be looking to get a slingshot maneuver back to Kerban. Otherwise, I don't think that there is enough fuel for the return trip using the direct flight, no tug or refueling approach.