Aichi D3A

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Aichi D3A
Aichi D3A1 from carrier Akagi.
Type	Carrier-based dive bomber
Manufacturer	Aichi Kokuki KK
Maiden flight	January 1938
Primary user	Imperial Japanese Navy
Number built	1,486 (470 D3A1) (1,016 D3A2)

Aichi D3A1 in flight.

Aichi D3A2 during maintenance.

Aichi D3A1 "Val" dive bombers prepare to take off from a Japanese aircraft carrier during the morning of 7 December 1941 to attack Pearl Harbor.

The Aichi D3A (99式艦上爆撃機, Allied code name Val) was a World War II dive bomber produced by the Aichi company in Japan. It was the primary carrier-borne dive bomber in the Imperial Japanese Navy in the early stages of the war, and participated in almost all actions, including Pearl Harbor.

In the summer of 1936 the Japanese Navy issued the 11-Shi specification for a monoplane carrier-based dive-bomber to replace the existing D1A biplanes currently in service. Aichi, Nakajima and Mitsubishi all submitted designs, and Aichi and Nakajima were both asked for two prototypes each.

The Aichi design started with low-mounted elliptical wings inspired by the Heinkel He 70 Blitz. The fuselage looked quite similar to the Zero, although the entire plane was built much more sturdily to withstand the rigours of dive bombing. It flew slow enough that the drag from the landing gear was not a serious issue, so fixed gear were used for simplicity. The plane was to be powered by the 710 hp (529 kW) Nakajima Hikari 1 nine cylinder radial.

The first prototype was completed in December 1937, and flight trials began a month later. 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 prior to delivery to try to address the problems. Power was increased by replacing the Hikari with the 840 hp (626 kW) 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. The production models featured slightly smaller wings and increased power in the form of the 1,000 hp (746 kW) Kinsei 43 or 1,070 hp (798 kW) Kinsei 44. The directional instability problem was finally cured with the fitting of a long dorsal fin, and the aircraft actually became highly maneuverable.

Armament was two forward-firing 7.7 mm Type 97 machine-guns, and one flexible 7.7 mm Type 92 machine gun in the rear cockpit for defense. Normal bombload was a single 250 kg (550 lb) bomb carried under the fuselage, which was swung out under the prop on release by a trapeze. Two additional 60 kg (130 lb) bombs could be carried on wing racks located under each wing outboard of the dive brakes.

Starting with the attack on Pearl Harbor, the D3A1 took part in all major Japanese carrier operations in the first ten months of the war. They achieved fame during the Indian Ocean raid in April 1942 when the D3A1s scored with over 80% of their bombs during attacks on the cruisers HMS Cornwall and HMS Dorsetshire and the carrier HMS Hermes. In some cases they were pressed into duty as fighters, their maneuverability being enough to allow them to survive in this role.

In June 1942, an improved version of the D3A powered by a 1,300 hp (970 kW) Kinsei 54 was tested as 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 U.S. 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 the autumn of 1942, and most Model 11's were then sent to training units.

When the Yokosuka D4Y Suisei became available, the D3A2s ended up with land-based units or operating from the smaller carriers, which were too small to handle the fast-landing Suisei. When American forces returned to the Philippines in 1944, land-based D3A2's took part in the fighting but were hopelessly outdated and losses were heavy. By then many D3A1s and D3A2s were operated by training units in Japan, and several were modified with dual-controls as Navy Type 99 Bomber Trainer Model 12s (D3A2-K). During the last year of the war the D3A2s were pressed back into combat for kamikaze missions.

In 1945, Indonesian guerillas captured numerous ex-Japanese air bases (several numbers of D3A Val captured by indonesian guerillas) including Bugis Air Base in Malang (repatriated 18 September 1945). Most of the aircraft were destroyed during 1945-1949 when the former Dutch East Indies and the Netherlands were engaged in military conflict/police action in Indonesia.

[edit] Specifications (D3A1)

General characteristics

• Crew: Two, pilot and gunner
• Length: 10.2 m (33 ft 5 in)
• Wingspan: 14.37 m (47 ft 2 in)
• Height: 3.85 m (12 ft 8 in)
• Wing area: 34.9 m² (375.6 ft²)
• Empty weight: 2,408 kg (5,309 lb)
• Max takeoff weight: 3,650 kg (8,047 lb)
• Powerplant: 1× Mitsubishi Kinsei 44 , 798 kW (1,070 hp)

Performance

• Maximum speed: 389 km/h (231 knots, 242 mph)
• Range: 1,472 km (795 nm, 915 mi)
• Service ceiling: 9,300 m (30,500 ft)

Armament

• 2 forward 7.7 mm (0.303 in) Type 97 Light Machine Guns
• 1 rear 7.7 mm (0.303 in) Type 92 Heavy Machine Gun
• 1 × 250 kg (550 lb) or 2 × 60 kg (130 lb) bombs

[edit] Specifications (D3A2)

Aichi D3A2 with telescopic sight before take off.

Replica

General characteristics

• Crew: Two, pilot and gunner
• Length: 10.2 m (33 ft 5 in)
• Wingspan: 14.37 m (47 ft 2 in)
• Height: 3.85 m (12 ft 8 in)
• Wing area: 34.9 m² (375.6 ft²)
• Empty weight: 2,570 kg (5,666 lb)
• Max takeoff weight: 3,800 kg (8,378 lb)
• Powerplant: 1× Mitsubishi Kinsei 54 , 969 kW (1,300 hp)

Performance

• Maximum speed: 430 km/h (232 knots, 267 mph)
• Range: 1,352 km (730 nm, 840 mi)
• Service ceiling: 10,500 m (34,450 ft)

Armament

• 2 fixed forward 7.7 mm (0.303 in) Type 97 machine guns
• 1 aimed rear 7.7 mm (0.303 in) Type 92 machine gun
• 1 × 250 kg (550 lb) or 2 × 60 kg (130 lb) bombs

[edit] External links

• Matsuura, Joao Paulo Julião (1997). Aichi D3A. Retrieved on September 10, 2006.

[edit] Related content

Designation sequence

• D1A - D2A - D3A - D4Y - D5Y

Related lists

• List of bomber aircraft
• List of military aircraft of Japan