The B7A Ryusei was developed to meet the Imperial Japanese Navy Air Service’s 1941 16-Shi specification for a carrier-based attack bomber to succeed the Nakajima B6N Tenzan and Yokosuka D4Y Suisei in service.
Designed for the new Taihō-class carriers, which began construction in July 1941, the B7A could exceed the previous 11 m (36 ft) length limit due to the Taihōs’ larger deck elevators.
Chief Engineer Toshio Ozaki opted for a mid-wing configuration to accommodate an internal bomb bay and provide clearance for the aircraft’s 3.5 m (11 ft) four-bladed propeller.
This design choice led to the use of an inverted gull wing, similar to the F4U Corsair, to reduce the main landing gear’s length.
The wings included extendable ailerons for additional flap functionality and dive brakes located just outside the fuselage.
For carrier storage, the B7A’s wings could hydraulically fold, shortening the wingspan from 14.4 m (47 ft) to about 7.9 m (26 ft).
The Japanese Navy mandated the use of the 1,360 kW (1,825 hp) Nakajima NK9C Homare 12 radial engine, anticipated to be the standard in the 1,340 kW (1,800 hp) to 1,641 kW (2,200 hp) range.
A later B7A2 model incorporated a 1,491 kW (2,000 hp) Nakajima Homare 23 engine.
Despite its advanced design, the B7A’s payload capacity did not surpass that of its predecessors, but it did feature an internal bomb bay with dual high-load attachment points, enabling it to carry two 250 kg (550 lb) bombs.
Specifications
Crew
2
Length
11.49 m (37 ft 8 in)
Wingspan
14.4 m (47 ft 3 in)
Height
4.075 m (13 ft 4 in)
Wing area
35.4 m2 (381 sq ft)
Empty weight
3,810 kg (8,400 lb)
Gross weight
5,625 kg (12,401 lb)
Max take-off weight
6,500 kg (14,330 lb)
Powerplant
1 × Nakajima NK9C Homare 12,
18-cylinder air cooled radial piston engine
1,361 kW (1,825 hp) for take-off
1,245 kW (1,670 hp) at 2,400 m (7,874 ft)
1,163 kW (1,560 hp) at 6,550 m (21,490 ft)
Propellers
4-bladed constant-speed propeller,
3.5 m (11 ft 6 in) diameter
Performance
Maximum speed
567 km/h (352 mph, 306 kn) at 6,550 m (21,490 ft)
Range
1,852 km (1,151 mi, 1,000 nmi)
Ferry range
3,037 km (1,887 mi, 1,640 nmi)
Service ceiling
11,250 m (36,910 ft)
Rate of climb
9.6 m/s (1,890 ft/min)
Time to altitude
4,000 m (13,123 ft) in 6 minutes, 55 seconds
Wing loading
158.9 kg/m2 (32.5 lb/sq ft)
Power/mass
0.242 kW/kg (0.147 hp/lb)
Armament
Guns
2× 20 mm (0.787 in) cannon in the wings
1× 7.92 mm (0.312 in) Type 1 machine gun
Or
13 mm (0.512 in) Type 2 machine guns in the rear cockpit.
Bombs
800 kg (1,764 lb) of general ordnance
Or
1× 800 kg (1,764 lb) torpedo.
Sources Japanese Aircraft 1910–1941-R C Mikesh & A Shorzoe. The Xplanes of Imperial Japanese Army & Navy 1924-1945-Illustrated Warplane History.
Japanese Aircraft of the Pacific War-Rene Francillon.
Japanese Imperial Army Navy Aircraft Color Markings-Koku Fan 42.
Japanese Military Aircraft Illustrated-Bunrindo No. 711.
Japanese WW2 Aircraft in Colour Volume 1-Martin Ferkl.
