Hi, so I'm just getting into SSTO building and I'm hitting a snag. I have FAR installed and used some of their planes, and it went pretty smoothly, more or less. But then I get to my designs and things fall apart. I understand the basics of getting to about 20k, and can tweak my designs to do that reliably. However, once I get to the cut over from jets to rockets, my own designs always start tumbling. It's uncontrollable and not recoverable every time. There's usually quite a bit of rocking to start, and then a full tumble. I've tried SAS, ASAS with RCS, and the avionics package. I've tried cutting off the jets earlier (around .14 air intake) to make sure I'm not having flame outs. I've tried cutting the jets and coasting before engaging the rocket and I've tried running them simultaneously. Either way, the same result every time. Here's a picture of my latest design. Generic, sure, but it's mine and I want it to work Any tips or help is greatly appreciated.