Something about Super-A Cruisers before Maru-5 Project.
Source: 早川幸夫，スーパー・クルーザー「超甲巡」覇王伝説，月刊《丸》，2013年5月号 (Monthly "Maru", May 2013).
The author stated that in a 1934 document named "Required National Defense Force from Treaty-Break to 1940" (条約決裂後ノ昭和十五年度ニオケル国防所要兵力表), that IJN's original plan was to change the main armament of Mogami-class cruiser to 10-inch (25 cm) guns. Still, it was estimated unreasonable, so Mogami-class eventually had 8-inch (20 cm) guns.
In the time when IJN discussed the Maru-3 project (about 1935-36), the term "Super A Cruiser" (超甲巡) was first mentioned in the document "Post-Treaty Era Required National Defense Force in 1940"(无条約昭和十五年度末ニ於ル国防所要兵力表), that IJN wanted to build 2 super-A cruisers with 10-inch (25 cm) guns as night battle flagships in the Second Fleet. The ideal organization for the capital ships in 1940 was:
First Fleet: 6x Modernized Old Battlehips (Fuso, Yamashiro, Ise, Hyuga, Nagato, Mutsu) + 2x Fast Battleships (2x Kongo-Class)
Second Fleet: 2x New Battleships (2x Yamato-Class later) + 2x Fast Battleships (2x Kongo-Class) + 2x Super-A Cruisers
However, Yamato-class battleships came out with 27 kt speed, not 30 kt, so, in the end, all 4 Kongo-class battleships were listed in the Second Fleet. The Fleet didn't need more night battle flagships, and the super-A cruisers were canceled.
Specifications (Maru-3 Super-A Cruiser, as planned):
Displacement: 15000 t
Main Armament: 4xII 25 cm, possibly had torpedoes (Fukui Shizuo had the opinion that it had, claimed by the author.)
Armor: Unknown, requirement: Resist 25 cm shells at a distance >20000 m, Resist 20 cm shells at a distance >12000 m.
Speed: 36 kt
It's a pity that the author didn't give a picture of them, but he stated that they were like an enlargement of treaty cruisers (the "large cruisers" indeed XD).
Source: 早川幸夫，スーパー・クルーザー「超甲巡」覇王伝説，月刊《丸》，2013年5月号 (Monthly "Maru", May 2013).
The author stated that in a 1934 document named "Required National Defense Force from Treaty-Break to 1940" (条約決裂後ノ昭和十五年度ニオケル国防所要兵力表), that IJN's original plan was to change the main armament of Mogami-class cruiser to 10-inch (25 cm) guns. Still, it was estimated unreasonable, so Mogami-class eventually had 8-inch (20 cm) guns.
In the time when IJN discussed the Maru-3 project (about 1935-36), the term "Super A Cruiser" (超甲巡) was first mentioned in the document "Post-Treaty Era Required National Defense Force in 1940"(无条約昭和十五年度末ニ於ル国防所要兵力表), that IJN wanted to build 2 super-A cruisers with 10-inch (25 cm) guns as night battle flagships in the Second Fleet. The ideal organization for the capital ships in 1940 was:
First Fleet: 6x Modernized Old Battlehips (Fuso, Yamashiro, Ise, Hyuga, Nagato, Mutsu) + 2x Fast Battleships (2x Kongo-Class)
Second Fleet: 2x New Battleships (2x Yamato-Class later) + 2x Fast Battleships (2x Kongo-Class) + 2x Super-A Cruisers
However, Yamato-class battleships came out with 27 kt speed, not 30 kt, so, in the end, all 4 Kongo-class battleships were listed in the Second Fleet. The Fleet didn't need more night battle flagships, and the super-A cruisers were canceled.
Specifications (Maru-3 Super-A Cruiser, as planned):
Displacement: 15000 t
Main Armament: 4xII 25 cm, possibly had torpedoes (Fukui Shizuo had the opinion that it had, claimed by the author.)
Armor: Unknown, requirement: Resist 25 cm shells at a distance >20000 m, Resist 20 cm shells at a distance >12000 m.
Speed: 36 kt
It's a pity that the author didn't give a picture of them, but he stated that they were like an enlargement of treaty cruisers (the "large cruisers" indeed XD).
