Each proposed 18-inch, 50-calibre gun was expected to throw a roughly 1,550-kilogram shell at about 800 metres per second. That combination promised enormous kinetic energy and made the battery a plausible driver of the next naval-gun arms race. Rival powers might answer with still larger weapons, perhaps even 20-inch guns. The engineering caveat is that rate of fire falls sharply once calibre rises much beyond 18 inches.
Notable Point · 16:43-18:42
Number 13's 18-inch, 50-calibre striking power
Number 13's proposed guns combined enormous shell energy with a calibre large enough to push rival navies toward still more extreme weapons.