Help with this Rocket Collapsing.

[Hakuryu]

I had the same issues with a similar rocket, and it is the tri-couplers that is the culprit. Once down to a single fuel tank and engine underneath a load like that, both of the tri-coupler spots, where they slim to a single connection, are incredibly wobbly.

Not sure why people say you can't use them that way though... works fine for me.

What I do, is put the structural small framework pieces radially around both the delivery vehicle and the the cargo, sticking out, and then run struts between them, in effect strengthening that entire portion of the rocket.

[Specialist290]

Another possibility is to mount the engines radially to the main fuel tank with the fat I-beam, then connecting the lifter directly to the tank itself. No fairings to worry about at all.

You'll probably also need to add fuel lines between the tank and the engines to make sure they're actually getting fuel, of course.

[Rockhem]

Another possibility is to mount the engines radially to the main fuel tank with the fat I-beam, then connecting the lifter directly to the tank itself. No fairings to worry about at all.

You'll probably also need to add fuel lines between the tank and the engines to make sure they're actually getting fuel, of course.

I just slapped on 4 to the sides instead of the bottom and, works like a charm.