Balancing an SSTO for Both Takeoff and Landing?

[Sauron]

So, I've got myself a fairly effective SSTO. It can make orbit with between 800 and 300 m/s of delta V. On takeoff it's fairly well balanced--no huge problems. However, landings? Not so much. I have the fuel to make a safe powered landing on the turbojets, but I'm struggling with unpowered gliding-landings/controlled crashes into the ocean (if necessary ) because the thing becomes extremely rear-heavy when it runs out of fuel.

[Cal'Mihe]

Though it would disturb the clean lines of your fuselage, you could move the rocket fuel tank to between the cockpit and the engines. As you yourself point out, the movement of the fuel creates an imbalance.

Alternatively look at the position of the wings. If you can move enough of the lift backwards, then the shift in center of mass would matter less.

[Nao]

Remember that you can transfer fuel to the front tanks to change balance. (to the rocket fuel tank and after that's full to the cockpit tank) It his should be enough. If not then you probably need a proper tail

[bsalis]

Balancing an SSTO for Both Takeoff and Landing?

For me this is the key issue of building a good SSTO Spaceplane. It is something you need to consider from the start.

I see you have put a rocket fuel tank on the nose, presumably to balance it for flying to orbit. You should not do this. You have to balance dry mass with dry mass and fuel mass with fuel mass. In order for the CoM not to drift too much, the fuel needs to be balanced around it.

[the_bT]

In addition to anything already posted, if you have your control surfaces near the COG they will become significantly less powerful. It's a problem with most of the Delta-wing designs when the COG drifts to the back of the craft. While a craft that is not properly balanced is always at least a bit tricky to fly, if you lack control authority too you are not going to live most of the time.

Or in other words, if you have enough control authority you can land anything

The further a control surface is from COG the more control authority it will provide. Two things can be done then:

1. Fit control surfaces to the front, which is often easy to do but will not do stability any good. (Though new-ASAS will probably cure that problem)

2. Move control surfaces to the back, behind COG. This is often hard to do in SSTO's though. In your specific design it would probably be easiest to do if you have the wings swept further back and add control surfaces to the tips similar to this:

[Sathurn]

My advice start with a fuel tank part. And keep your CoM in the center of it.