Why does this happen o.O

[Wikwoo]

When I jettison the SRBs on this rocket, the bottom half of it disappears.

http://www./view/h8eq7kp4qkbatwq/Rocket%20with%20plane%20on%20top.craft

There's the craft file. It uses B9Aerospace, KWRocketry and MechJeb2.

Can anyone tell me why this is happening?

[Captain Sierra]

For starters, B9 has multiple plugins, some of which were updated for .23 but the updated version isn't in the B9 download. Those plugins might be screwing you over. Mechjeb is also plugin powered. I assume these are KW SRBs so try testing them alone without MJ and B9. If it still does it, I'd file a bug in the KW thread, otherwise, it's a mod interaction.

[MaverickSawyer]

Are you sure you're not ejecting the boosters too soon, and having them smash into the lower stage, causing it to completely vaporize?

[Bobe]

Are you sure you're not ejecting the boosters too soon, and having them smash into the lower stage, causing it to completely vaporize?

That would be my assumption as well.

I can't really check the craft file now, but if you don't have any, try putting some ullage motors (from KW) or sepratrons on the SRBS. A pair at the top and bottom of each booster, obviously facing away from the rocket, should be enough to eject them clear of the rocket and avoid any collisions. Before I started this practice, I would often get unlucky and have my boosters hit my engine.

[gslarmour]

sepratrons on the SRBS. A pair at the top and bottom of each booster,

I second this. If you are hurting for part count, use radial chutes at the top so the SRBs are pulled away.

[Taki117]

The SRB nosecones for KW have Sepratron type motors in them, you can tell where they will fire based on the small hard to see circles on the side of the nosecone. Be sure these are pointing towards your rocket and that the engine of your booster is about level with the engine of your main stage. You can Also hit F3 to check your flight log and see if anything has collided into anything else resulting in the rapid unplanned disassembly

[Wikwoo]

I have four separatrons on each SRB, but it could be because of the built in separatrons. I'll do some more testing and report back here asap

[Wikwoo]

Well, I've found the cause of this.. The SRBs run out of fuel during the gravity turn, and there's one SRB that happens to be on the topside of the rocket when it gets jettisoned. So it just goes up and comes back down and explodes on the rocket, destroying the bottom stage. I suppose I could try to circumvent this with some clever rotating during the gravity turn... back to testing.