Second stage swings upside down like a clock pendulum?

[sledgeweb]

This is early on in career mode.

So, since the update, I have an odd experience where my rocket flies up to about 15k feet, then I separate. The upper stage immediately swings upside down and just sort of swings back and forth like a pendulum on a grandfather clock. The upper stage consist (from bottom up) of an LV-909, an FL-200 tank, the storage bay with a couple goo canisters inside, a small reaction wheel, and then the sputnik ball unmanned control pod. Something like this would fly correctly in previous versions of the game. I guess maybe it's balancing issues, and I understand there are new aerodynamics to take into account  but it just doesn't look right at all the way it behaves in mid-flight. Is this the way the mechanics are supposed to work now? It seems to me, in reality, if something like that was going in a certain direction - even if it's heavier at the top, the momentum is going to keep it going that way. There is nothing changing much aerodynamically when the first stage separates. It doesn't matter if I fire the 909 or just leave it off - as soon as I separate, the rocket immediately starts swinging upside down like a pendulum. It really takes me out of the game. I don't understand why they seemed to have the physics right on that before, and now it just seems silly.

Is this just me?

[Randazzo]

Judging from your description of what is happening, I would wager that the ass-end of your rocket is heavier than the top. You can stick some fins near the rear end to try and counter this, but if the center of mass is too far behind the center of drag, it will continue to flip.

I don't know the actual weights off-hand, but I'm fairly confident the fuel tank + 909 is heavier than the service bay and sputnik.

[chrisb2e9]

Pictures would really help here. But i'm guessing that you have a lot of drag inducing objects near the top. Once you stage the rocket, the drag at the top overcomes the rocket's ability to counter it with thrust.

If you have farings, use them. Otherwise use control surfaces on the bottom of that second stage to give you the ability to counter act the drag.

[zarakon]

You can also move the fuel tank above the storage bay to move that mass higher

If you add fins to the bottom of your second stage, you'll need to add more to the bottom of your first stage as well, so that you don't flip over during first-stage flight

Another idea is to cram the probe core into the storage bay so that you can put an aerodynamic nosecone at the top to reduce drag there