The Aichi B7A Ryusei (Shooting Star) 'Grace' was a large torpedo bomber designed for use on a new generation of Japanese aircraft carriers, but that only saw limited service from land after the Japanese carrier fleet was destroyed.
Work on the B7A began in response to a 16-Shi specification issued in 1941 for a large carrier borne torpedo bomber to replace the Nakajima B6N torpedo bomber and Yokosuka D4Y dive bomber. The new aircraft was to be able to carry two 551lb bombs or six 132lb bombs internally or one 1,764lb externally, carry two 20mm cannon and one 13mm machine gun, have a top speed of 354mpg and range of 2,072 miles and be as manoeuvrable as the Mitsubishi A6M Zero. Earlier carrier aircraft were limited to a length of 11m (36ft 1 1/16in) in order to allow them to use the lifts on existing aircraft carriers, but that restriction was lifted for the new design, and the eventual B7A was 37ft 8in long. The new aircraft was to be powered by the Nakajima Homare eighteen cylinder engine, which was under development at the same time as the aircraft.
The Aichi design team was led by Chief Engineer Norio Ozaki, supported by Morishige Mori and Yasushiro Ozawa. The requirement for an internal bomb bay meant that they needed to adopt a mid-wing configuration, but with straight wings that would have required unacceptably long main landing gear, and so an inverted gulf wing configuration was chosen (just as on the Chance-Vought Corsair). The wings were given drooped ailerons that could be used as flaps and dive breaks. The wings folded hydraulically, with the hinge outside the flaps. All aircraft carried two 20mm cannon in the wings. Early production used a flexibly mounted 7.2mm machine gun in the rear cockpit, but this was later replaced with the 13mm Type 2 machine gun.
The new aircraft was given the internal Aichi designation AM-23 and the Navy designation Navy Experimental 16-Shi Carrier Attack Bomber (B7A1). The first prototype was completed in May 1942, but the development programme was interrupted by problems with the Homare 11 engine. Nine prototypes were built using that engine, before work moved onto the 1,825hp Homare 12 engine.
The Homare 12 powered version was ordered into production in 1944 as the Navy Carrier Attack Bomber Ryusei (Shooting Star) B7A2. It was produced in two factories - an Aichi plant at Funakata and the 21st Naval Air Arsenal at Omura. Production was slow at both plants, with only 80 built by Aichi and 25 at Omura, and production at Aichi was stopped when the factory was destroyed by an earthquake in May 1945. Total production was thus only 114, including the nine prototypes.
One aircraft was given a 2,000hp Homare 23 engine, and if the war had lasted longer this would have become the main production version. There were also plans for a B7A3 Ryusei Kai, to be powered by a 2,200hp Mitsubishi MK9A engine, but these were disrupted by the May 1945 earthquake. Finally a smaller, faster replacement, the Mokusei (Jupiter) was in the earliest stages of development when the war ended.
By the time the aircraft entered production, the Japanese Navy had lost its carriers, and so it saw limited service on land, with the Yokosuka and 752nd Kokutais.
Engine: Nakajima NK9C Homare 12 18-cylinder radial
Power: 1,825hp take-off, 1,670hp at 7,875ft, 1,560hp at 21,490ft
Wing span: 47ft 3in
Length: 37ft 8in
Height: 13ft 4in
Empty Weight: 8,400lb
Loaded Weight: 12,401lb
Maximum Weight: 14,330lb
Max Speed: 352mph at 21,490ft
Climb Rate: 6min 55sec to 13,125ft
Service Ceiling: 36,910ft
Maximum Range: 1,888 miles
Armament: Two fixed forward firing 20mm cannon in wings, one 13mm/0.51in machine gun in rear cockpit
Bomb-load: One 1,764lb Long Lance torpedo