A digression from the topic thread:

NUCLEARSPACE MESSAGE BOARD (ACTIVE) > OPEN FORUM >> Let the Space Shuttle Fly!

I provide this partly as background on spaceplanes and crew launch vehicles -apart from "Mini-Shuttles" like the Hermes or HOPE which like the US "Shuttle orbiter" were to be used on-orbit for loing periods of time and before being axed were (like the Shuttle) too big for effective launch escape systems.
http://astronautix.com/craft/hermes.htm
http://astronautix.com/craft/hope.htm

If you're trying to make the crew cabin separable/survivable, like the F-111Aardvark, the payload capacity drops to zear zero (the extra size and complexity also makes separation from a transonic/hypersonic vehicle dubious). If all you're making is a crew vehicle, then reduced payload isn't a problem. Make the crew cabin survivable, and leave the internal (airlock pass-through) cargo behind.
http://www.fas.org/man/dod-101/sys/ac/f-111.htm

Some background on some designs for spaceplanes which got to relatively advanced design stages:
The designs being floated by the older SLI initiative (pre-Columbia) for the spaceplane variant of the CEV are strongly reminiscent of the old HL-20 PLS (Personnel Launch System) of the late '80s.

HL-20
www.astronautix.com/craft/hl20.htm
oea.larc.nasa.gov/PAIS/HL-20.html
HL-42
www.astronautix.com/craft/hl42.htm

In particular I want to point out some factors of the design philosophy of the HL-20/42: small size, low payload which was limited to what could be safely carried inside the plane and passed through the ISS airlocks. In particular note the reliance on OTS parts and "airplane-like servicability", nothing radically advanced (the bane of the X-33 and I'm convinced part of its design philosophy: make it as "Whiz-Bang" as possible, to funnel as much tax dollars to the contractor as possible before it's cut. A Lock-Mart trademark)

 The HL-20 in turn was derived from the Soviet sub-scale spaceplane tests of the early '80s (which were ultimately flown only as tests of the Buran Shuttle's TPS)
www.astronautix.com/craft/mig10511.htm
http://www.astronautix.com/craft/bor4.htm
http://www.astronautix.com/craft/uraeptor.htm
http://www.astronautix.com/craft/spiralos.htm

Note that the Uragan was a competitor to the USAF X-20 Dyna-Soar orbital interceptor/bomber.
http://deepcold.com/
http://www.astronautix.com/craft/dynasoar.htm

Some other Soviet/Russian spaceplanes which make varying amounts of sense. Note the reliance on HTO piggyback launch, which has very little precedent, especially for a production manned vehicle.
http://www.astronautix.com/lvs/spil5050.htm

http://www.astronautix.com/lvs/bizan.htm
http://www.astronautix.com/lvs/system49.htm
http://www.astronautix.com/craft/maks.htm