The Aichi D3A, known to the Imperial Japanese Navy as the “Type 99 Carrier Bomber” and to the Allies as “Val,” was a World War II carrier-borne dive bomber.
It served as the IJN’s primary dive bomber and participated in nearly all its operations, including the attack on Pearl Harbour.
The Aichi D3A holds the distinction of being the first Japanese aircraft to bomb American targets during the war, starting with Pearl Harbour and extending to U.S. bases in the Philippines like Clark Air Force Base.
The D3A also attacked Australia’s mainland on a few occasions.
Moreover, it sank more Allied warships than any other Axis aircraft during the conflict.
In the middle of 1936, the Japanese Navy released the 11-Shi specification for a monoplane carrier-based dive bomber to succeed the D1A biplane then in operation.
Aichi, Nakajima, and Mitsubishi each presented designs, and Aichi and Nakajima were requested to produce two prototypes each.
The Aichi prototype featured low-mounted elliptical wings, taking inspiration from the Heinkel He 70 Blitz.
Its slow flight speed meant that drag from the landing gear was not a significant issue, allowing for the use of fixed gear to keep things simple.
The aircraft was equipped with a 529 kW (709 hp) Nakajima Hikari 1 nine-cylinder radial engine.
The first prototype was finished in December 1937, and flight testing commenced the following month, leading to its designation as the D3A1.
However, initial trials were unsatisfactory; the aircraft lacked power and exhibited directional instability during wide turns, while tighter turns often resulted in snap rolls.
The dive brakes experienced heavy vibration when deployed at the design speed of 200 knots (370 km/h), prompting the Navy to request a higher dive speed of 240 knots (440 km/h).
To address these issues, the second aircraft underwent significant modifications before delivery.
The power was enhanced by replacing the Hikari engine with the 626 kW (839 hp) Mitsubishi Kinsei 3, housed in a redesigned cowling, and the vertical tail was enlarged to improve directional stability.
The wingspan was slightly increased, and wash-out was added to the outer leading edges to prevent snap rolls, along with reinforced dive brakes.
These modifications resolved all issues except for the directional instability, which was sufficient for the D3A1 to surpass the Nakajima D3N1.
In December 1939, the Navy commissioned the aircraft as the Navy Type 99 Carrier Bomber Model 11.
The production models had marginally smaller wings and more power, provided by either the 746 kW (1,000 hp) Kinsei 43 or the 798 kW (1,070 hp) Kinsei 44 engines.
The persistent directional instability was finally rectified by installing a long dorsal fin-strake beginning midway down the rear fuselage, which also significantly improved the aircraft’s manoeuvrability.
In June 1942, an enhanced version of the D3A1, equipped with a 969 kW (1,299 hp) Kinsei 54 engine, was tested and designated as the D3A2 or Model 12.
The increased power resulted in a reduced range, leading to further modifications with extra fuel tanks to extend its operational range for effective combat over the Solomon Islands.
Referred to by the Navy as the Model 22, it started replacing the Model 11 in front-line units by autumn 1942, with most Model 11s reassigned to training roles.
Although some late production D3A1 models were equipped with a propeller spinner, this feature became standard on the D3A2.
Specifications
Crew
2
Length
10.195 m (33 ft 5 in)
Wingspan
14.365 m (47 ft 2 in)
Height
3.847 m (12 ft 7 in)
Wing area
34.9 m2 (376 sq ft)
Empty weight
2,570 kg (5,666 lb)
D3A1
2,408 kg (5,309 lb)
Gross weight
3,800 kg (8,378 lb)
D3A1
3,650 kg (8,050 lb)
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
1st prototype
710 hp (530 kW) Nakajima Hikari I
2nd prototype
840 hp (630 kW) Mitsubishi Kinsei 3
D3A1 Model 11 (early production)
1,000 hp (750 kW) Mitsubishi Kinsei 43
D3A1 Model 11 (late production)
1,070 hp (800 kW) Mitsubishi Kinsei 44
Propellers
3 bladed metal constant speed propellers
Performance
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
2 x 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
&
2x 60 kg (130 lb) bombs under the wings.
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.
