The primary torpedo bomber of the Imperial Japanese Navy (IJN) during the start of World War 2 (1939-1945) were two separate designs, the Nakajima B6N "Tenzan" and the Kugisho D4Y "Suisei" - both being detailed elsewhere on this site. By the time these two platforms had hit the frontlines, work was already underway on an all-new torpedo-/bomb-delivery platform becoming the classic Aichi B7A "Ryusei" (also detailed elsewhere on this site). First-flying in May of 1942, just 114 of these aircraft were completed as losses to the Japanese carrier force began to mount - this, in turn, relegated the new aircraft to a land-based dive-bombing role before the end of the war in 1945.
Against this backdrop, Aichi Kokuki was approached in 1945 with a new specification for a new attacker design designated "AM-26". The lack of aircraft carriers within the IJN inventory (and thus being forced to move forward with a carrier-less strategy) meant that certain features common to carrier-borne aircraft were nixed from the new design, namely the complex folding wings. What IJN authorities sought was a highly-capable bombing platform with suitable self-defense measures coupled with inherently good performance and handling - all built to a smaller specification than seen in Aichi's earlier limited-run B7A series - a lighter-weight aircraft would help produce a faster, more maneuverable fighter-like bombing platform.
Aichi engineers went to work by evolving their existing B7A3 production variant to expedite project and cleanly fit the requirements of the new IJN specification. This resulted in a warplane that mimicked the form and function of the earlier torpedo bomber though finished off with simpler, straight-lined wings without the wing-folding component. The mainplanes were retained just ahead of midships in a low-mounting. To this was added an engine housed at the nose and, aft of this installation, was the two-man cockpit (tandem-seating) under a "greenhouse-style" canopy typical of Japanese warplanes of the era. The cockpit sat at the aircraft's center mass. The tail would incorporate a traditional, proven triple-plane arrangement and ground running was by way of a retractable "tail-dragger" configuration.
Metal would be used to skin the most important sections of the structure while fabric would cover the control surfaces on the wings.
The Mitsubishi MK9A air-cooled radial piston engine with an output of 2,200 horsepower was to power the aircraft, presumably driving a four-bladed propeller unit at the nose as in the B7A.
The armament suite encompassed a mix of cannon, machine guns, bombs, and torpedoes. 2 x 30mm Type 5 series automatic cannons were to be installed at the wings (one gun per wing member) while a single 13mm Type 2 air-cooled machine gun (on a trainable mounting) would be featured in the rear-facing cockpit. Up to 1,754lb of drop-ordnance could be carried, this being either conventional drop bombs (for dive-bombing) or a single torpedo (for ship strikes). All told, the aircraft would have the capability to strafe targets, engage in air-to-air combat, bomb ground targets, or sink surface targets - making for an all-in-one-solution much-needed at this point in the war.
With preliminary work quickly completed by Aichi engineers, the aircraft then fell to Japanese authorities who liked what they saw and selected the design for adoption/production. The aircraft would be taken into inventory under the designation of "B8A" and assigned the name of "Mokusei" (meaning "Jupiter").
However, all this came all too late for the aircraft as the end of the war in August of 1945, in turn, spelled the end of the B8A Mokusei, keeping the B8A as another one of the war's late "paper airplanes" destined to never see the light of day.
Specifications on this page are estimates make on the part of the author.