Modern-Aviation

Performance
Powerplant: 1 × Mitsubishi Kinsei 54 14-cylinder air-cooled radial piston engine, 970 kW (1,300 hp) for take-off
                      1,200 hp (890 kW) at 3,000 m (9,800 ft)
                      1,100 hp (820 kW) at 6,200 m (20,300 ft)
Other engines
            710 hp (530 kW) Nakajima Hikari I - 1st prototype
            840 hp (630 kW) Mitsubishi Kinsei 3 - 2nd prototype
            1,000 hp (750 kW) Mitsubishi Kinsei 43 - D3A1 Model 11 (early production)
            1,070 hp (800 kW) Mitsubishi Kinsei 44 - D3A1 Model 11 (late production)
Propellers: 3-bladed metal constant-speed propeller
Maximum speed: 430 km/h (270 mph, 230 kn) at 6,200 m (20,300 ft)
D3A1: 387 km/h (240 mph; 209 kn) at 3,000 m (9,800 ft)
Cruise speed: 296 km/h (184 mph, 160 kn) at 3,000 m (9,800 ft)
Range: 1,352 km (840 mi, 730 nmi)
D3A1: 1,472 km (915 mi)
Service ceiling: 10,500 m (34,400 ft)
D3A1: 9,300 m (30,500 ft)
Time to altitude: 3,000 m (9,800 ft) in 5 minutes 48 seconds
D3A1: 3,000 m (9,800 ft) in 6 minutes 27 seconds
Wing loading: 108.9 kg/m2 (22.3 lb/sq ft)
D3A1: 104.6 kg/m2 (21.4 lb/sq ft)
Power/mass: 3.9 kg/kW (6.4 lb/hp)
D3A1: 4.9 kg/kW (8 lb/hp)

Armament
Guns: 2x forward-firing 7.7 mm (0.303 in) Type 97 aircraft machine guns in the forward fuselage upper decking + 1x 7.7 mm (0.303 in) Type 92 machine gun on a flexible mount in the rear cockpit
Bombs: 1x 250 kg (550 lb) under the fuselage and 2x 60 kg (130 lb) bombs under the wings

In mid-1936, the Japanese Navy issued the 11-Shi specification for a monoplane carrier-based dive bomber to replace the existing D1A biplane then in service. Aichi, Nakajima, and Mitsubishi all submitted designs, with the former two subsequently being asked for two prototypes each.

The Aichi design started with low-mounted elliptical wings inspired by the Heinkel He 70 Blitz. It flew slowly enough that the drag from the landing gear was not a serious issue, so fixed gear was used for simplicity. The aircraft was to be powered by the 529 kW (709 hp) Nakajima Hikari 1 nine-cylinder radial engine.

The first prototype was completed in December 1937, and flight trials began a month later, after which it was designated as D3A1. Initial tests were disappointing. The aircraft was underpowered and suffered from directional instability in wide turns, and in tighter turns it tended to snap roll. The dive brakes vibrated heavily when extended at their design speed of 200 knots (370 km/h), and the Navy was already asking for a faster diving speed of 240 knots (440 km/h).

The second aircraft was extensively modified before delivery to try to address the problems. Power was increased by replacing the Hikari with the 626 kW (839 hp) Mitsubishi Kinsei 3 in a redesigned cowling, and the vertical tail was enlarged to help with the directional instability. The wings were slightly larger in span and the outer sections of the leading edges had wash-out to combat the snap rolls, and strengthened dive brakes were fitted. These changes cured all of the problems except the directional instability, and it was enough for the D3A1 to win over the Nakajima D3N1.

In December 1939, the Navy ordered the aircraft as the Navy Type 99 Carrier Bomber Model 11 (kanjō bakugekiki, usually abbreviated to 艦爆 kanbaku). The production models featured slightly smaller wings and increased power in the form of the 746 kW (1,000 hp) Kinsei 43 or 798 kW (1,070 hp) Kinsei 44. The directional instability problem was finally cured with the fitting of a long dorsal fin-strake which started midway down the rear fuselage, and the aircraft actually became highly maneuverable.

In June 1942, an improved version of D3A1, powered by a 969 kW (1,299 hp) Kinsei 54, was tested and designated as D3A2 or the Model 12. The extra power reduced range, so the design was further modified with additional fuel tanks to bring the total tankage to 900 L (240 US gal), giving it the range needed to fight effectively over the Solomon Islands. Known to the Navy as the Model 22, it began to replace the Model 11 in front-line units in autumn 1942, and most Model 11s were then sent to training units. While some late production models of D3A1 were fitted with a propeller spinner, it became a standard with D3A2.

On December 7, 1941, the Japanese Imperial Navy launched 353 aircraft from six carriers,1 in a surprise attack, against United States military installations, on the island of Oahu, Hawaii. The aircraft included Mitsubishi A6M2s (Zero), Nakajima B5Ns (Kate) and Aichi D3As (Val). The Aichi D3A led the first wave of attacks, and it was the first Japanese aircraft to drop bombs on American targets.2 129, Aichi D3As were used as part of the Japanese task force that attacked Pearl Harbor.3 Despite its obsolescence, the D3A took part in all major Japanese carrier operations in the first ten months of the war, after the attack on Pearl harbor. Before WW II, they saw only limited action from land bases in China and Indo-China. During the campaign in the Indian Ocean, D3As placed more than 82% of their bombs on target during attacks on the cruisers, HMS Cornwall, and HMS Dorsetshire and the carrier HMS Hermes in April, 1942.