A roughly 140 mm dual-purpose weapon offered an alternative to separate anti-surface and heavy anti-aircraft batteries during the 1920s. Existing 5.5-inch guns provided a starting point, though mount design, elevation, and effective heavy anti-aircraft performance would still require development. A successful twin mounting would sit above destroyer armament in shell weight while remaining lighter than a conventional six-inch cruiser battery. The idea shows how an early capital-ship choice might have influenced later cruiser conversions and fleet air-defence armament.
Notable Point · 17:38-20:24
A 5.5-inch dual-purpose battery for the Nelson era
An alternate secondary battery develops Britain's existing 5.5-inch gun into a twin dual-purpose mount for capital ships and perhaps converted cruisers.