The Aichi M6A-1 Seiran attack floatplane was to be housed in water-tight containers and released from Japanese Navy I-400 class submarines. The wings rotated back and folded flat against the fuselage. Part of the horizontal and vertical stabiliser also folded.
The first prototype flew in November 1943 and a total of 28 were built. The design was in full production in 1945, with the aircraft and its submarine counterparts being readied for an attack on the Panama Canal when the war ended.
The Aichi M6A Seiran (translated as “Mountain Haze”) was a single engine design, powered by a Atsuta 32 inline piston engine of 1,400 horsepower driving a three-blade propeller. Crew accommodations amounted to one personnel and standard armament is known to consist of a single 500lb bomb, mounted under the fuselage presumably. Design of the aircraft consisted of a low-monoplane type with a single rudder aft. The cockpit was situated at center above the wing roots.
At the end of May 1945, at the instigation of Admiral Yamamoto, a series of I-400 submarines were ordered, each able to carry three special duty aircraft. A catapult stretched from the cylinder hangers in the starboard hold, forward to the bow.
The aircraft were twin seater Aichi M6A1 Seiran seaplanes specially designed for a bombing raid on the Panama Canal. The Seirans were powered by German Daimler-Benz DB601A of 1400 hp.
They were designed to drop off the crew after the raid, be ditched beside the submarine and sink at once.
On 25 June 1945 the plan was halted.
On 25 June 1945, Imperial Japanese Headquarters halted preparations for the Japanese 1st Submarine Flotilla to attack the Panama Canal, and issued new orders: In view of the American threat to the main Japanese islands, the 12 Seiran aircraft were ordered to find a suitable opportunity to launch a kamikaze raid (operation Hikari) against US aircraft carrier, but the surrender came before the operation could be carried out.
A land-based derivative known as the M6A1K “Seiran Kai” was utilized for pilot training purposes. Landing gear was of the standard two-front with a tail wheel at rear for this land-based variant.
Aichi M6A1 Seiran
Engine: 1 x Aichi Atsuta Type 32 inline radial, 1,400hp.
Wingspan: 12.26 m / 40 ft 3 in
Length: 11.64 m / 38 ft 2 in
Height: 4.58 m / 15 ft 0 in
Wing Area: 27.0 sq.m / 290.63 sq ft
Take-Off Weight: 4040-4445 kg / 8907 – 9800 lb
Empty Weight: 3300 kg / 7275 lb
Maximum Speed: 295mph (474kmh; 256kts)
Cruise Speed: 300 km/h / 186 mph
Maximum Range: 1,243miles (2,000km)
Service Ceiling: 32,480ft (9,900m)
Armament: 1 x 13mm machine-gun, 850-kg torpedo or 1 x 800-kg bomb or 2 x 250-kg bombs
Crew: 2
Hardpoints: 1
All Aero 