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The Aichi D3A (Val)

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Codenamed 'Val' by the Allies, the Aichi D3A was the first Japanese aircraft to bomb United States military installations at Pearl harbor.

by
Larry Dwyer

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Aichi D3As prepare to takeoff for the attack on United States military installations at Pearl Harbor, December 7,1941.
(Photo: National Archives)

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. The Aichi D3A led the first wave of attacks and was the first Japanese aircraft to drop bombs on American targets.2 129 Aichi D3A aircraft 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 the attack on Pearl Harbor, 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 per cent of their bombs on target during attacks on the cruisers, HMS Cornwall and HMS Dorsetshire and the carrier HMS Hermes in April 1942.4

Inspired by the Heinkel He 70, the D3A was designed to supersede the D1A2, Navy Type 96 Carrier Bomber. The Navy ordered two prototypes with the first prototype being completed in December, 1937. The first prototype was the Nakajima D3N1, powered by the 730-hp Nakajima Hakari 1 radial engine but showed many shortcomings during initial flight-testing. It was found to be under-powered and had a tendency to snap roll in tight turns. The dive brakes were ineffective and vibrated violently when diving at 90 degrees. However, the aircraft did show promise because it had a strong airframe and the overall handling characteristics were good, with the exception to snap roll in tight turns. The second prototype was the Aichi D3A1, configured with a fixed landing gear to eliminate extra weight and maintenance problems of a retractable landing gear system. The Aichi prototype was extensively modified to overcome the shortcomings of the Nakajima design. Engine power was increased to 840 hp with a Mitsubishi Kinsei 3 fourteen-cylinder radial engine, and a redesigned cowling was installed. The wing span was increased, the vertical stabilizer was enlarged, and improved dive brakes were installed. The better performing Aichi D3A1 was selected to go into production under the designation Navy Type 99 Carrier Bomber Model 11. 5

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The production D3A1s engine power was increased with a 1,000 hp Mitsubishi Kinsei 43, engine, or 1,070 hp Kinsei 44, engine. The wing area was decreased slightly and a large dorsal fin was installed to correct directional stability problems. The aircraft was equipped with only two forward-firing 7.7 mm Type 97 machine-guns and one flexible rear-firing 7.7 mm Type 92 machine gun. The normal bomb load was a single 250 kg (551 lb) bomb carried under the fuselage, which swung down and forward on arms before release. Two additional 60 kg (132 lb) bombs could be carried on wing racks located under each wing outboard of the dive brakes. 6

In June 1942 the D3A was introduced and was powered by a 1,300 hp Kinsei 54 engine. The production version of the D3A2 featured an increased range to 915 miles (1,472 km) with a fuel capacity of 1,079 liters (237-4 Imp gal). Externally the aircraft was almost identical to the D3A1 with the exception of a propeller spinner and a rear canopy section that was longer and more pointed. It was designated Navy Type 99 Carrier Bomber Model 22 and began to replace the Model 11 in front-line units in the autumn of 1942. When the much faster Yokosuka Suisei became available, the D3A2s were relegated to land-based units and to those operating from the smaller carriers which had a deck inadequate for the Suisei's higher landing speed. In 1944 when the American forces returned to the Philippines the D3A2s took an active part in the bitter fighting but were hopelessly out performed and losses were heavy. By then many D3A1s and D3A2s were operated by training units in Japan and several were modified as Navy Type 99 Bomber Trainer Model 12s (D3A2-K).7 During the last year of the war, D3A2s were mostly relegated to second-line duties. They also engaged in kamikaze attacks and experienced a high loss rate, with poor compensating results.8

Specifications:
  D3A1 D3A2
Dimensions:
Wing span: 47 ft 1 15/16 in (14.365 m) 47 ft 1 15/16 in (14.365 m)
Length: 33 ft 5 3/8 in (10.195 m) 33 ft 5 3/8 in (10.195 m)
Height: 12 ft 7 15/32 in (3.847 m) 12 ft 7 15/32 in (3.847 m)
Weights:
Empty: 5,309 lb. (2,408 kg) 5,666 lb. (2,570 kg)
Loaded: 8,047 lb (3,650 kg) 8,378 lb (3,800 kg)
Performance:
Maximum Speed: 240 mph (209 kt)
@ 9,845 ft (3,000 m)		 267 mph (232 kt)
@ 20,340 ft (6,200 m)
Service Ceiling: 30,500 ft. (9,300 m) 34,450 ft. (10,500 m)
Range: 840 miles (1,351 km) 915 miles (1,472 km)
Powerplant D3A1: Powerplant D3A2:
Mitsubishi Kinsei 43, 1,000 hp or,
Kinsei 44, 1,070 hp. engine. 		Kinsei 54, 1,300 hp engine.
Armament:
Two forward-firing 7.7 mm Type 97 machine-guns and one flexible rear-firing 7.7 mm Type 92 machine gun. A single 250 kg (551 lb) bomb carried under the fuselage and,
two additional 60 kg (132 lb) bombs carried on wing racks.

Endnotes

1. David Mondey, ed. The International Encyclopedia of Aviation. New York, Crown Publishers, Inc., 1977. 217.
2. Rene J. Francillon, Japanese Aircraft of the Pacific War, Aichi D3A. Annapolis, Maryland: Naval Institute Press, 1995. 271.
3. David Mondey. The Concise Guide to Axis Aircraft of World War II. New York: Smithmark Publishers, 1996. 9.
4. Francillon. 274.
5. Ibid. 272-273.
6. Ibid. 273.
7. Ibid. 275.
8. Mondey. 10.


Courtesy of
The Aviation History On-Line Museum.

 

 

Aichi D3A (Val)

 

Aichi D3A
Role Carrier-based dive bomber
Manufacturer Aichi Kokuki KK
First flight January 1938
Introduced 1940
Primary user Imperial Japanese Navy
Number built 1,486
(470 D3A1)
(1,016 D3A2)

The Aichi D3A, 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.

 

Design & Development

 

In mid-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 stronger to withstand the rigours of dive bombing. It flew slowly 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 engine.

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.

 

Operational History

 

Click on Picture to enlarge
Aichi D3A1 from carrier Akagi
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.
Aichi D3A from Shokaku return to their carrier after attacking the US carrier Enterprise during the Battle of the Eastern Solomons in August 1942.
D3A with Type 98 bomb
Aichi D3A2 with telescopic sight before take off.

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 propeller 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 British 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 autumn 1942, and most Model 11s 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 D3A2s 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 were captured by Indonesian guerillas, including at 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.

 

Specifications  (D3A1)

pecificatiSons (D3A1)

General characteristics

Performance

Armament
 

 

Specifications  (D3A2)

 

General characteristics

Performance

Armament
 

Wikipedia

 

 

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