Cheaper way to space!? A supergun.

Instead of hauling their own fuel for propellent, which adds to its
weight, why not have manned craft launched from massive high-altitude
cannons? Why not further what the late-Gerald Bull envisioned (see
world.std.com/~jlr/doom/bull.htm) to build a supergun that could
launch projectiles large enough to be duplicated as manned capsules?
That way there would be little or no need for external boosters to be
hauled alongside the manned vehicle, greatly reducing the per pound
flight costs.

The gun could be large enough to shoot the craft into near-low earth
orbit and then small internal rockets could be used to get the craft
further into space. The craft could be sized such that it replicated
the apollo.

I imagine the dimensions would be at least 500 meters long, 30 meters
in diameter, and require an explosive shot of several tons of tnt.

Ciao.