Aichi B7A “Grace” of No. 752 Navy Attack Squadron, 5th Company, Katori Base, Chiba, April 1945. This Grace is finished in the standard IJN camouflage of dark green over gray (or possibly silver duralumin base with no paint). There is no white outline around the hinomarus.

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 bomb load of up to 500kg, or the carriage of an 800kg torpedo externally, coupled with high maximum speed and long range, a powerful engine was essential. The navy selected what was virtually an experimental power plant for this task: the Nakajima Homare 11 twin-row radial developing around 1342kW.

Aichi entrusted the task of meeting this requirement to a team headed by Norio Ozaki. 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.

VARIANTS

* B7A1 : Prototypes. Nine built.

* B7A2 : Two-seat torpedo, dive-bomber aircraft for the Imperial Japanese Navy.

* B7A2 Experimental : One aircraft fitted with a 2,000-hp (1491-kW) Nakajima Homare 23 radial piston engine.

* B7A3 : Proposed version. Not built.

UNITS ALLOCATED

752nd and Yokosuka Kokutais.

TECHNICAL DATA

Description: Single-engined carrier-borne torpedo and dive-bomber. All-metal construction with fabric-covered control surfaces.

Accommodation: Crew of two in tandem enclosed cockpits.

Powerplant:

One Nakajima NK9B Homare 11 eighteen-cylinder air-cooled radial, rated at 1,800 hp for take-off, 1440 hp at 1,800 m and 1,560 hp at 6,400 m, driving a constant-speed four-blade metal propeller (B7A1 protorypes).

One Nakajima NK9C Homare 12 eighteen-cylinder air-cooled radial, rated at 1,825 hp for take-off, 1,670 hp at 2,400 m and 1,560 hp at 6,550 m, driving a constant-speed four-blade metal propeller (production B7A2).

One Nakajima NK9H-S Homare 23 eighteen-cylinder air-cooled radial, rated at 2,000 hp for take-off and 1,570 hp at 6,850 m, driving a constant-speed four-blade metal propeller (one experimental B7A2).

One Mitsubishi MK9A ([Ha-43] 11) eighteen-cylinder air-cooled radial, rated at 2,200 hp for take-off, 2,070 hp at 1,000 m and 1,930 hp at 5,000 m, driving a constant-speed four-blade metal propeller (B7A3).

Armament:

Two wing-mounted 20 mm Type 99 Model 2 cannon and one flexible rear-firing 7.92 mm Type 1 machine-gun (B7A1 and early production B7A2).

Two wing-mounted 20 mm Type 99 Model 2 cannon and one flexible rear-firing 13 mm Type 2 machine-gun (late production B7A2).

Bomb-load: one 800 kg torpedo or up to 800 kg of bombs.

	B7A2
Dimensions:
Span	14.40 m
Length	11.49 m
Height	4.08 m
Wing area	35.4 m2
Weights:
Empty	3,810 kg
Loaded	5,625 kg
Maximum	6,500 kg
Wing loading	158.9 kg/m2
Power loading	3.1 kg/hp
Performance:
Maximum speed	306 kt at 6,550 m
Climb to	4,000 m
in	6 min 55 sec
Service ceiling	11,250 m
Normal range	1,000 naut miles
Maximum range	1,640 naut miles

Production: A total of 114 B7As were built as follows:

Aichi Kokuki K.K. at Funakata:

9 B7A1 prototypes (May 1942-Feb 1944)

80 B7A2 production aircraft (May 1944-July 1945)

Dai-Nijuichi Kaigun Kokusho at Omara (Sasebo):

25 B7A2 production aircraft (Apr 1944-Aug 1945)