A plausible X-1 successor would fuse the long-range cruiser concept with the heavy forward torpedo battery developed for the T class. One twin 5.25-inch mounting would preserve gun power without forcing the boat to expose a full broadside. Because the submarine would spend most of a 12,000-mile cruise surfaced, designers would also need retractable anti-aircraft weapons and stronger surface defense. The design would retain the conservative idea of using a gun to compensate for limited torpedo capacity, while later hydrodynamic improvements could gradually pull it toward a true submarine rather than a submersible surface raider.
Chapter · 26:18-29:23
A practical successor blends T-class weapons with X-1 range
The likely British successor combines a ten-torpedo bow salvo and one twin 5.25-inch mount with better surface defenses and a more pragmatic hull.