Vojta

I am not using the engine shroud (created by a decoupler), I used structural panels.

The struts are attached to the panels covering the second stage engines. The parts offset into the second stage are scaled up C7 adapters. There are no radial decouplers. I tried building something that looks like a Proton rocket, which is using radially attached fuel tanks connected to the center fuel tank.

Thank you. High thrust was the cause of explosion. Throttling down worked.

Nothing happens to the first stage or payload, only the second stage blows up completely. The rocket start wiggling more and more until it explodes. I have tried launching it multiple times and it's always the same : 2 parts of stage 2 collide (including the two fuel tanks) and it disappears instatly. I also tried launching the rocket without payload and it worked okay.

Second stage of my rocket keeps exploding 9 seconds after launch. I used TweakScale and Procedural Fairing. Reason: High G forces (very powerful thrust) were destroying the rocket.