SRBs ripping themselves off

[Wizard Kerbal]

I'm flying an american space shuttle replica with 2 Clydesdale booster. I attached struts from the SRBs to the external tank, and usually, it works fine. 

I noticed upon launch that they started wobbling a bit, but nothing major. My ascent was fine, peaking at 3.8G right before booster cutoff. I went to detach them, but 1 came off without pressing any buttons and ripped off the wing. This happened once before at Max-Q when the booster was still, on? thrusting? burning fuel? burning fuel on a flight a few months ago.

Does anyone know why this might be happening?

Edited June 21, 2021 by Wizard Kerbal
I didn't know parachutes sunk, and can morph through the seafloor. I only learned that after my shuttle crash-landed and the chute came off.

[18Watt]

No idea why it happens, but it does.   Here are a few things I’ve done to get that under control.

• Turn on Rigid Attachment for the boosters and the decouplers.   You may need to have Advanced Tweakables enabled to see this button in the Part Action Window (PAW).
• Use a strut near the top and bottom of each booster.  Maybe two at each end.
• Use Autostrut on the boosters and the decouplers.  Again, I don’t remember if this requires Advanced Tweakables enabled or not.

I suspect the boosters have so much thrust that when coupled with the oscillations of a moving rocket the force is enough to separate them.

[Wizard Kerbal]

The boosters are contributing a lot of the thrust when they shut off, that sounds right.

I would check if I have autostrut and rigid attachment on, but i'm interested in where this parachute is going.

[jimmymcgoochie]

I would suggest just adding MOAR STRUTS!!!1! on the top and bottom of the boosters, but also activating autostruts from the nosecones on the boosters to the root part, and from the boosters themselves to the grandparent part. Rigid attachment can make things brittle and easy to snap off, so I’d avoid using that if possible.

[imcute]

need more struts