Gh.K. 43 (Anti-Tank Gun)

A German 50mm anti-tank gun designed during World War II but not adopted for service. It was intended to be a more powerful and effective anti-tank weapon than the earlier Gh.K. 40 but never saw widespread use.

Gb 48 (Germany)

A German 170mm anti-tank gun, a prototype weapon that was never fully developed or deployed. It was designed to counter the most formidable Allied tanks but was deemed too impractical for widespread use.

Fx-131 (Japan): Rocket-Powered Trainer Aircraft

A Japanese prototype rocket-powered trainer aircraft designed in the late 1940s, incorporating experimental rocket propulsion, but never entered production due to the end of World War II.