Aichi M6A

M6A1 Seiran
Role	Submarine-launched dive / torpedo bomber
Manufacturer	Aichi Kokuki KK
First flight	1943
Introduction	1945
Retired	1945
Primary user	IJN Air Service
Produced	1943–1945
Number built	28 + 1 M6A2 Prototype

The Aichi M6A Seiran (晴嵐^?, "Clear Sky Storm" or "Mist on a Fair Day") was a submarine-launched attack floatplane designed for the Imperial Japanese Navy during World War II. It was intended to operate from I-400 class submarines whose original mission was to conduct aerial attacks against the United States.

From the late 1920s, the Imperial Japanese Navy had developed a doctrine of operating floatplanes from submarines to search for targets. In December 1941, Commander-in-Chief of the Japanese Combined Fleet, Admiral Isoroku Yamamoto, proposed constructing a large fleet of submarine aircraft carriers (also designated STo or sen-toku — special submarine) whose purpose was to mount aerial attacks against American coastal cities. The submarines would surface to launch their aircraft by catapult, submerge to avoid detection, then surface again to retrieve the aircrews who would ditch their planes nearby. By June 1942, the plan was to build a fleet of eighteen such subs. This was later cut to nine, then five and finally just three as Japan's wartime fortunes declined.

To equip the submarine aircraft carriers, the Imperial Japanese Navy Air Service requested that Aichi design a folding attack aircraft with a range of 1,500 km (810 nmi) and a speed of 555 km/h (300 kn). Aichi was already manufacturing under license, the D4Y1 Suisei (Judy), a relatively small single-engined carrier dive bomber with exceptionally clean lines and high performance. Detailed engineering studies commenced in an effort to modify the Susei for use aboard the I-400 submarines but the difficulties in doing so were eventually judged insurmountable and a completely new design was initiated.

...
Wikipedia