SSTO flatspins on re-entry

[Fireheart318]

Hey, I'm having some trouble gliding my booster... thing back to the KSC. It has no trouble getting a payload into orbit, but it doesn't like coming back down. At roughly 1200m/s, the craft spins out of control on the yaw axis. I've tried moving the wings around, and added more yaw control, neither of which actually helped that much. What can I do to keep it from crashing?

Important to note, there are two wing strakes with Elevon 4's on them underneath the wings, and I've drained the craft's fuel to give you a better idea of what it's like when dry. It crashes regardless of whether the airbrakes are deployed or not.

[IronMaiden]

It has to do with your center of pressure and center of mass relationship. Your center of mass is very far back, by your engines, so all the parts in the front have a very long lever arm to torque your craft around. Whereas your vertical stabilizers are almost on top of the center of mass so they have virtually no torque to prevent unwanted yaw. To fix this you need more substantial vertical stabilizers and they need to be moved further back towards your engines. Here's some more info that should help.

[Deddly]

Yep, I agree with @IronMaiden on that one. Additionally, the flat nose causes a great deal of drag, and that will make the effect even more pronounced.

Also, moved to Gameplay Questions

[pmborg]

I recommend to advance the center of gravity to front and put a cone in the nose to reduce the drag or a heat shield.

Let me know the results