Hd-11 (United Kingdom)

A British heavy tank prototype developed during World War II. It featured a 17-pounder gun and thick armor, but it was not adopted due to its high cost.

Hd-13 (Italy)

An Italian heavy tank prototype developed during World War II. It featured a 90mm gun and thick armor, but it was never deployed due to production limitations.

Hd-4 (Germany)

A German heavy tank design from 1944, intended to be a successor to the Tiger II. It featured a 128mm gun and even thicker armor than its predecessor, but it was never built due to the war’s end.

Hd-5 (Japan)

A Japanese heavy tank prototype developed in the 1940s. It featured a 75mm gun and thick armor, but was never deployed due to production limitations.

Hd-7 (United States)

An American heavy tank prototype developed during World War II. It featured a 90mm gun and thick armor, but it was deemed too heavy and complex for production.

Hd-8 (United States)

An American heavy tank prototype developed during World War II. It featured a 105mm gun and even thicker armor than the Hd-7, but it was also deemed too complex for production.

Hd-1 (Germany)

A German heavy tank prototype developed in the early 1930s, featuring a powerful 105mm gun and heavy armor. It was ultimately rejected in favor of the Panzer III and Panzer IV designs.

Hd-2 (Germany)

A German heavy tank design proposed in 1942, intended to be a successor to the Tiger I. It featured a 128mm gun and thicker armor, but was never built due to resource constraints.

Hd-3 (Germany)

A German heavy tank design project initiated in 1943. It aimed to develop a super-heavy tank with a 150mm gun and exceptionally thick armor, but the project was abandoned due to logistical challenges.

Hber-5

The fifth prototype of the Heinkel He 177, built in 1941 and incorporating further modifications and refinements. It was used for final testing and evaluation before the aircraft was cleared for production and operational deployment.