From the schematics we have procured, we have learned that military-class ships are constructed in a wholly different way, around a hardened plastasteel frame laced with super-conductive wiring for heat dissipation that gives them their toughness, as well as allows them to endure high speeds and accelerations within a planet's atmosphere.
Tougher ships will have the ARMOR parameter; armor negates an amount of damage equal to its rating after each hit, making small weapons less useful against them.