Due to the lightweight balloon tank construction, the entire body of the Atlas rocket could be placed in orbit.
A missile doing single-stage-to-orbit is not the thing I find impressive about Cochrane's rocket, though. A missile lifting a payload as big as herself (the part that would have been the second stage in a Titan II) to a high trajectory that for all practical purposes should qualify for an orbit is what's far beyond the capabilities of today's rocket technology. And never mind that warp engines might well be much heavier than rocket fuel, making the feat even more staggering.
That this is outdated tech as of the 2050s should not surprise us, though, since the 1990s already featured feasible human interplanetary travel (and the odd interstellar foray), the 2000s saw the launch of interstellar probes that apparently found their targets in a matter of decades, and the 2030s had week-long trips to Mars.
One really wonders how advanced the Franklin was for her time. Flashy new superfast engines, yeah, but perhaps bolted onto a ship that differed very little from the ones Earth launched in 2065 or so?
Timo Saloniemi