Asymmetrical spacecraft design - HELP NEEDED!

[MaverickSawyer]

I'm sure everyone here's seen the stock LearStar design. It's... clunky. And I didn't like how it handled in the atmosphere.

So I built this instead:

Runs on two Thumpers to help it off the pad, then is sustained by a Skipper and a linear aerospike on the spaceplane from the superb Mk2 Expansion Pack. And all in all, it handles the launch quite well. The aerospike has a trim feature courtesy of Klockheed Martin, and that's being used to help keep the pitch loads within the limits of the design.

Well, most of the time, anyways.

About 5 seconds before fuel depletion in the external tank, there's a spike in the pitch moment that cannot be compensated for by the trim and the engine gimbals combined. I get a maxed out nose down control from MechJeb, and I pitch nose up about 90 degrees. Then, I run out of fuel, drop the tank, and go back to flying to orbit normally... I have plenty of fuel available to make up for this... it's just ANNOYING.

Anyone have any experience with this kind of situation? And if you did, how did you fix the issue?

[Red Iron Crown]

In stock, you can tweak the thrust limit on the booster motor down a bit before you get to that critical point.

With mods, you can use something like Throttle Controlled Avionics or Davon Throttle Control to automagically vary the thrust to control attitude.

[MaverickSawyer]

In stock, you can tweak the thrust limit on the booster motor down a bit before you get to that critical point.

With mods, you can use something like Throttle Controlled Avionics or Davon Throttle Control to automagically vary the thrust to control attitude.

Huh. I'll have to look into that. Until then, I just cut loose the ET with some seperatrons and an engine shutdown command. It worked better than waiting for BECO, but I still flipped around some due to the engine trim.