Soon after the advent of aircraft and submarines during World War I, the combined operation of those two tools were considered by many countries. But ended up being just the Imperial Japanese Navy that may put it to practical usage. At outbreak regarding the Pacific War, numerous large-sized submarines for the Imperial Japanese Navy were built with catapult and tiny observation-type aircraft designed to strike harbors and to bomb the U.S. mainland. Acknowledging the success of previous attacks by the Imperial Japanese Navy, it made a decision to plan surprise assault missions to the Panama canal by special submarineborne aircraft at the start of 1942. The plane was the Aichi M6A1 Seiran, created solely with this one exceptional mission. It had been in May 1942 as soon as the Aichi Aircraft business received requirements to build up and create a unique attack bomber. At first, the utilization associated with then brand new Suisei bomber with some improvements was proposed, but the conversation was discovered not practical due to the trouble to possess interchangeability of major assemblies. On November 1943, the initial prototype made its maiden journey. Undergoing a few improvements, the Aichi Aircraft Company received a purchase for restricted manufacturing from Navy in 1944. The engine ended up being a 12-cylinder liquid-cooled Atsuta 32, that was based on the German Daimler-Benz DB603. A 12.7mm, type-2 flex mounted machine weapon had been equipped during the rear, and a torpedo or a 250kg/800kg bomb could possibly be carried. The Seiran was to be carried by the I-400 class submarine inside hanger tube of 4.2m in diameter and 30.5m in length. The hanger pipe was with the capacity of holding three Seirans. These people were stored on catapult launching automobiles with armaments for fast ejection after surfacing. To cope with the space limitation, the Seiran was built to save space by folding the wings. The wings were pivoted on the main spar where it joined up with the fuselage. By rotating the key side downward, the wing could lie back flat against the sides of this fuselage. The outer portions of every stabilizer and elevator hinged at the 90cm through the fuselage centerline and folded downward. Straight clearance ended up being acquired by folding the tip of this fin towards right. 28 Seirans including a Nanzan, its ground-take-off-and-landing equivalent, had been produced in total by 1945, and submersible companies for them, the I-400 and I-401, were finished almost at the same time. Obtaining the target changed from Panama Canal to the U.S. Navy aircraft carriers staged at Ulithi Atoll due to the change in priorities the war demanded, the first Submarine Flotilla including the I-400 and I-401 with three Seirans each departed Japan on 23 July 1945 for their first and final objective. On 15 August, the flagship I-401 monitored a radio message from headquarters, informing them of Japan's surrender and flotilla was bought to come back to the nearest port in Japan. Hence the opportunity to show the Seiran's worth was missed forever.
