Study of the Shuttle RTLS abort mode

Why? Well, it occurred to me that if the Shuttle was designed to do this, perhaps it isn't an impossible maneuver.

It was designed to do a RTLS abort after the SRB's discontinued firing, which is a little over 2 minutes into the flight.  Up to T plus 4 minutes, the maneuver was still possible.

The idea is to design a RTLS for the first stage of a reusable rocket.  The second stage continues with the payload to orbit.

http://en.wikipedia.org/wiki/File:Space_Shuttle_vs_Soyuz_TM_-_to_scale_drawing.png

 The trick in this proposed system is to have almost 95% of the entire mass at launch supported by this airframe.  On second thought: why?  You only need the structural support for the stack at launch.  On the return to launch site, your mass is going to be much less, meaning the wings only need to support less than 5% of the launch mass.  Therefore, the strongest part of the structure needs to resist gravity, which means straight down the middle.

On return, the wings can support the much lighter craft.  My original thought was to have the tanks in the wings, but that means more weight supported by the wings, which is a non starter.  That appears to be the stumbling block.  Perhaps the wings can support the engines?  The fuel would stay in the "fuselage".