Shipborne Dive Bomber First flight: 1934 Aichi

Since Nakajima's programs to create carrier-based dive bombers according to the requirements of 6-Ci and 7-Ci did not bring the desired results, Kaigun Koku Hombu in 1933 was forced to develop the 8-Ci specification. In accordance with it, the new two-seat aircraft had to have higher performance than the unsuccessful Nakajima samples, as well as be distinguished by its structural strength, which allows bombing in a steep dive, and sufficiently high maneuverability.

This time, the command of the Japanese Imperial Navy announced a competition and sent demands to the 1st Aviation Arsenal in Yokosuka, as well as to the Nakajima and Aichi firms. The latter, having no experience of its own in designing this type of aircraft, decided to take advantage of the technical assistance of the German firm Heinkel, with which it maintained close ties. At the suggestion of the German partners, the Japanese purchased from them one copy of the He 66 single-seat dive bomber (export version of the He 50) with an air-cooled engine Siemens "Jupiter" with a capacity of 490 hp Shortly after the arrival of the He 66 in Japan, the Aichi designers, led by Tokuihiro Goake and Yoshimichi Kobayashi, began to refine the aircraft to meet the requirements of the 8-C. They redesigned and strengthened the landing gear for use from aircraft carriers, installed a landing hook, replaced the Siemens engine with a four-bladed wooden propeller with a 580-horsepower 9-cylinder air-cooled Nakajima Kotobuki 2 KAI-1 engine with a two-bladed metal propeller, and equipped an additional cockpit gunner-observer. The aircraft modified in this way received the factory designation AB-9 and the military DIAL. Comparative tests that took place in 1934, in which the Nakajima D2N1 and Yokosuka D2Y1 aircraft also took part, revealed the superiority of the Aichi aircraft, which proved to be more stable and maneuverable in flight.

As a result, in December of the same 1934, a contract was signed with Aichi for the serial production of the aircraft, which received the official designation "Light deck bomber Type 94 Model 11" (D1A1 Model 11).

The aircraft was a biplane of metal construction with fabric covering. Unlike the prototype, production D1A1s were equipped with a new engine cowl and had a swept wing along the leading edge, as well as a reshaped rudder. In addition, the tail spike was replaced by a wheel. Small arms consisted of two synchronized forward-firing 7.7-mm Type 92 machine guns and one of the same machine gun on a mobile mount in the gunner's cockpit to protect against attacks from enemy fighters from behind. The aircraft could carry two 30 kg bombs under the wings and one 250 kg bomb under the fuselage. The first 118 D1A1 aircraft were equipped with the Kotobuki 2 KAI-1 engine, the remaining 44 received a new engine - the Kotobuki 3, with a capacity of 640 hp - and designation D1A1 Model 12.

In 1936, the D1A1 was replaced by an improved version of the D1A2 Model 21. 428 aircraft of this modification (their production was discontinued in 1940) were equipped with more powerful Hikari 1 engines (730 hp), received landing gear fairings and a fuel tank with capacity increased from 535 to 730 liters.

Design. Nakajima Hikari 1 air-cooled 9-cylinder radial engine with 750 hp. It is equipped with two-bladed fixed-pitch metal propellers.

To reduce aerodynamic drag, the landing gear wheels on D1A2 modification aircraft were covered with massive fairings. On machines of earlier versions, fairings were absent.

The fuselage structure is metal, the skin is mixed: metal in the front part and linen in the middle and tail.

The upper and lower wings of the D1A were of metal construction and fabric covering and were characterized by a slight sweep of 5° along the leading edge.

Armament. Two synchronized 7.7 mm type 92 machine guns and one 7.7 mm type 92 machine gun on a mobile mount; Bombs on an external sling: 1 × 250 kg + 2 × 30 kg.

Combat use. D1A dive bombers were actively used during the Sino-Japanese War, both from the decks of aircraft carriers and from land bases. They were widely known for the sinking on December 12, 1937 of the American gunboat Penay, which evacuated the staff of the US Embassy from Nanjing. By the time the war in the Pacific began, 68 D1A2 dive bombers were being cleaned in parts of the second line. The rest served in training units. They were not used in combat, but the Americans assigned them the code name "Susie".

Photo	Description
	Drawing D1A1 Модель 12

Bibliography

• Japan Warplanes of World War II /Oleg Doroshkevich/
• Deadly Susie. Aichi D1A deck dive bomber /Evgeny Aranov/
• Encyclopedia of military engineering /Aerospace Publising/