Just what is the SWORD scale? It's taxed my addled brain for a while. I always start with what I think is easy, the biggest spacecraft in the SWORD fleet must be the Saturn V rocket, especially when sat on the mobile crawler, which we know when both together, were the 'biggest vehicle in the world'. But that's the real world, not Century 21. Just how big was Zero-X, the Nuclear Ferry or the Booster Rocket? Going to the source must be the answer, an understanding of the comic strip you would think. Not so. Take a look at this illustration below from SOLO 20, June 1967.
Lots of SWORD for sure: PF2, PF3 (below) and NF and Booster Rocket (above). But the size comparison is impossible because of perspective. So, based on what I think I know, here's my best guess at a SWORD scale - in diagrammatic and font size representations below. Any other ideas/scales would be welcomed particularly anyone with any graphic skills whatsoever unlike yours truly!
Prospector Bug Ranger TF1,2,3
PF1 PF2 PF3
Saturn V Zero X Nuclear Ferry Booster