The requirement for a large torpedo/ dive-bomber for operation from a new, larger class of aircraft carrier caused the Imperial Japanese navy to draw up in 1941 the specification of an aircraft to replace the Nakajima B6N and Yokosuka D4Y. As this specification called for an internal bombload of up to 500kg, or the carriage of a 800kg torpedo externally, coupled with high maximum speed and long range, a powerful engine was essential. The navy selected what was virtually an experimental powerplant for this task: the Nakajima Homare 11 twin-row radial developing around 1342kW.
Aichi began work on this requirement, and its AM-23 prototype flew in mid-1942. This large aircraft, then designated Navy Experimental 16-Shi Carrier Attack Bomber (Aichi B7A1), was a mid-wing monoplane of inverted gull-wing configuration, a layout selected so that the main units of the retractable tail-wheel landing gear, mounted at the 'elbows' of each wing, would be as short as possible. A section of each outer wing panel folded for carrier stowage. The fuselage and tail unit were conventional, the former providing enclosed accommodation for a crew of two.
As might have been anticipated, the combination of problems from the air-frame, coupled with the teething troubles of the new engine, meant that it was almost two years before the type was ordered into production as the Navy Carrier Attack Bomber Ryusei (Shooting Star), or Aichi B7A2. Apart from nine prototype B7A1s, only 80 examples were completed by Aichi before its factory was destroyed in the
serious earthquake of May 1945; an
additional 25 were built by the Navai Air
Arsenal at Omura.
By the time these aircraft entered service,
when they were allocated the
Allied codename 'Grace', the Japanese
navy no longer had any carriers from
which they could operate, with the result
that they saw only limited use from land
bases.
