Reentering a Rocket with an Inflatable Heatshield

[A_name]

I’m currently building a rocket SSTO, similar to a Falcon 9 booster but it goes all the way into orbit with its payload. For practical, aesthetic and role playing purposes, I really want to the thing to reenter “nose” first with an inflatable heat shield on the front. Problem is, the heat shield produces tons of drag and makes the rocket want to flip during reentry. I’ve partially corrected the problem by:

 

-Pumping all remaining fuel to the front to act as ballast

-Adding RCS thrusters for attitude control

-Adding larger fins at the back for steering

-Adding airbrakes on the back to offset the heat shield’s drag

 

However, even with these measures taken sometimes I make it and others I won’t. In particular, there seems to be a zone in the higher atmosphere where the heat shield produces lots of drag but the fins and airbrakes don’t, and that is where the flipping happens. Once in the lower atmosphere, it seems the fins can bite on the air hard enough to keep me straight, but not higher up.

 

I was wondering what solutions you have found to this kind of problem.

[bewing]

There are no "good" answers to the problem. Switch to Vernors from RCS for more thruster power. More beefy reaction wheels. And/or rebuild your RV to be squattier and not so tall.

[Foxster]

As bewing says, there's no magic bullet for this one. 

You want the CoM as close to the heatshield as possible and you want plenty of drag at the back end, a lot of air brakes being the obvious solution there. 

For an Eve lander I had the engine mass and fuel near the heat shield, four reaction wheels and 12 air brakes at the back end. It still only just remained heat shield first.