sylvie369

Yes, my command pods are facing up. And it's clearly a matter of the thrusters/SAS pushing the rocket into the spin, not a matter of instability. I just watched a rocket flying just fine and suddenly the thrusters just knocked it over (and the SAS seems to be doing the same thing - killing the thrusters didn't help much). I know the aerodynamics models were changed recently, and I suppose that might have something to do with it. I've been flying KSP rockets for a few years now without ever having seen this problem before. If it's a matter of those rockets being unstable, they're unstable in a way they didn't used to be. All of these rockets would have flown fine six months ago. ================== Just now I noticed that if I send a Kerbal EVA while it's spinning, the spinning stops, until the Kerbal reenters the pod. Then it starts spinning up again like mad. I was able to cycle through that several times before finally the spinning pod flung the Kerbal off into space. Each time when he went EVA, the pod quickly stopped spinning. This was on a rocket that I'd flown out to a parking orbit about 1.1 million meters out without incident. Once out there it orbited just fine for a while, then began spinning end over end. Again, it seems to have nothing at all to do with rocket design or aerodynamics.

Oh, I just lost another one - one that had been flying normally - to this "phantom control input" problem. I was able to slow the spinning down by rotating the rocket 180 degrees so the control forces were working against the spin. I didn't think to look at whether or not it was using battery change. Hopefully I'll remember that next time. As the thrusters and SAS were causing the spin, the attitude indicators were showing forces. Before I manually rotated it, the pitch indicator was pinned to one side. After rotation, the yaw indicator was the one pinned. Is this "part clipping" something I can fix? Or should I forget about that as a possible cause?

I'll try that. Are you suggesting that alt-x could turn off phantom control inputs that are causing the spin?

It seems to be something much more than that. I could be flying nicely in orbit, engines off, stabilization on, holding me in the direction of the flight path, and all of a sudden it starts tumbling end over end. Several times I was stably in orbit with engines off when it started happening. Oof. And just now it started doing it in a capsule that had already safely splashed down in the water. That suggests that it has nothing to do with CG/CP relationships (it's just a capsule) or the thrusters (since there aren't any). Hmm. And if I turn SAS off, the water starts splashing like mad. ...? The water calms if I turn SAS back on, but the capsule keeps spinning. There's clearly something in the rocket that is forcing it to spin. It doesn't seem to be related to the rocket's environment, since I've now seen it start in the atmosphere, out in deep space, and in the ocean. In the ocean case right now the rocket (capsule) wasn't even moving when it started to spin.

Okay, I'm lost. I've been flying Kerbal rockets with fair success for quite a while, but now I cannot seem to build a rocket that doesn't start spinning wildly at some point in its flight. If thrusters are on as well as SAS, they fire in the direction that makes it spin MORE, not less. If I leave the thrusters off I still get the spinning, though later in the flight. I suspect this is a simple problem of the relationship between CG and CP (that after I've burned enough fuel it goes backwards and causes the problem). I understand CG/CP relationships in real rockets (I've built and flown hundreds of them), just not how to maintain the necessary relationship in KSP rockets. Anyway that doesn't explain why the automatic stabilization fires the wrong way. I don't know how to solve that. I also suspect that this has something to do with the change in physics that came with the recent update. Regardless, I no longer have any idea how to make rockets that fly reliably. Any hints?