Dive Bomber Yokosuka

On the morning of October 24, 1944, a lone single-engine aircraft appeared over the American squadron. Diving a comet through the explosions of anti-aircraft shells, he covered the aircraft carrier Princeton with a single 250-kg bomb. A fire followed, and then, at the time of the evacuation of the crew, a powerful explosion that severely damaged the nearby cruiser Birmingham. 229 people died, 420 were seriously injured ...

The plane that inflicted this heavy blow on the American fleet was the Susay-Kometa dive bomber - one of the most beautiful aircraft of the Second World War. It has been engineered with art that rivals those of the British Mosquito bomber. Even their fate is similar - designed as bombers, they were first used as reconnaissance aircraft and both were used as night fighters. But, despite its outstanding combat characteristics, the history of "Sussei" as it were ended with the defeat of Japan, and in comparison with the glory of "Mosquito" "Sussei" remained only in the hearts of rare aviation enthusiasts.

Already while the first D3A1 was being tested, the Imperial Navy issued a new 13-C mission for the next generation of dive bombers. Initially, the Japanese naval headquarters planned to put into production a modified version of Heinkel He 118. The fleet acquired from the firm "Ernst Heinkel AG" experienced Not 118 V4 and license to manufacture it. The aircraft was tested in the spring of 1938 in Japan under the designation DXHel "experimental naval attack aircraft type He". But it turned out to be too heavy for use from an aircraft carrier, and plans for its mass production were rejected after the plane was destroyed in the air. But the characteristics of the He 118 impressed the Japanese naval headquarters, and as a result, the 13-C specifications appeared for a two-seater dive bomber with a maximum speed of 515 km / h, a cruising speed of 425 km / h, a flight range of 1450 km with a 250-kg bomb and 2200 km without bombs. There was no competition for this task - the order was received by the 1st Naval Aviation Technical Arsenal in Yokosuka, which was supposed to develop a reduced version of the He 118 for use from small aircraft carriers.

Under the leadership of Chief Engineer Masao Yaman, Arsenal designers designed one of the most aesthetic single-engine bombers of World War II. The resulting D4Y1 barely resembled its progenitor He 118 - only the use of a 12-cylinder liquid-cooled engine Aichi "Atsuta" remained in common, which was a licensed version of the Daimler-Benz DB 601 A, which was on a German car. The aircraft had a wingspan of 11.5 m. Despite its small size, the D4Y1 carried the same amount of fuel as the larger D3A1 and had a bomb bay for 500 kg bombs. For use as a dive bomber, the aircraft had three electrically operated brake flaps. They stood right in front of the flaps. The fuel system included five unprotected tanks with a capacity of 1070 liters - one under the pilot's seat and four between the wing spars. Two 330-liter fuel tanks could be suspended under the wing. There was a 73-liter oil tank behind the engine. The defensive armament was the same as that of the D3A1: two synchronous 7.7-mm Type 97 machine guns and one movable 7.92-mm Type 1 machine gun in the rear of the cockpit. The plane could carry 560 kg of bomb load.

Development of the D4Y1 progressed slowly - the small Yokosuka design bureau was having a hard time coping with the many technical innovations used on the aircraft.

Since the Aichi "Atsuta" engine was not yet ready, the plane was equipped with a Daimler-Benz DB 600G purchased in Germany. The plane made its first flight in Yokosuka in December 1940. The flights were extremely successful, the characteristics were high, and the handling was pleasant. This was enough to start pre-production of the D4Y1. The next four prototype aircraft were also powered by imported DB 600G engines. By the time the testing of these machines was completed in 1941, it was decided to transfer production to the Aichi plant in Ettoku, since the naval arsenal did not have the necessary capacity. However, the rapid launch of the aircraft into production was prevented by the wing flutter during dive bombing tests. In this case, cracks appeared in the wing spar. Work on the pre-production vehicles for the Aichi engines had already gone far enough to change anything, and it was decided to finish them in the version of deck reconnaissance. The reconnaissance plane was equipped with a K-8 camera with a 250 mm or 500 mm lens. With engines Aichi AE1A "Atsuta" 1200 hp the aircraft was accepted into service under the designation "deck reconnaissance aircraft type 2 model 11" (Aichi D4Y1-C). At the same time, the aircraft retained the small arms, but the bomb racks were removed.

At a time when the D3A2s rushed into desperate attacks under heavy attacks from enemy fighters in the Solomon Islands area, the designers of Aichi and the Yokosuka Arsenal made every effort to redesign the D4Y1 wing. The wing received a reinforced spar and new air brakes. The aircraft was accepted for production in March 1943 under the designation "Susay naval bomber model 11". Thus, the production of the aircraft was limited for a long time: only two D4Y1-Cs were released in October and November 1942, five D4Y1-Cs in December 1941, six in February and seven in March 1942. However, after launching into series " Comets, "the total output of D4Y1 and D4Y1-C increased rapidly, reaching 76 machines in December. As the serial production expanded, new modifications of the aircraft were prepared. Thus, the "Susay" naval bomber model 11 "(D4Y1 KAI) resembled its predecessor and only differed in some structural reinforcement for launching an aircraft from aircraft carrier catapults. In the spring of 1944 he went into series D4Y2 with the Aichi AE1R "Atsuta" 32 engine with a capacity of 1400 hp. in five modifications: "model 12" with a glider "model 11"; "Susay" model 22 "(D4Y2 KAI) with catapult launchers;" Susay "model 12A" and "model 22A" with a 13-mm "type 2" machine gun installed in the rear part of the cockpit instead of the standard 7.92-mm "type one"; The "deck reconnaissance aircraft type 2 model 12" (D4Y2-C) was the previous version of the reconnaissance aircraft for the Atsuta -32 engine.

The 11th Naval Arsenal in Hiro was also connected to the production of B4Y, delivering 215 aircraft from April 1944 until the end of the war. A small number of D4Y2s produced by this arsenal were converted into Sussei-E (D4Y2-S) night fighters. In this case, all bomber and aircraft carrier equipment was removed, and a 20-mm Type 99 gun was installed in the rear fuselage for forward firing at an angle to the horizon. However, this modification had little success - even if the pilot detected the target, the low climb rate of the vehicle did not allow taking a position for an attack.

With the reinforcement of the wing, the Susay has become a very effective dive bomber with characteristics significantly higher than that of the Curtiss SB2C Helldiver. The main problem of the aircraft was its power plant - neither Daimler-Benz DB 601 A, nor its licensed copy of Aichi - "Atsuta" or Kawasaki Na-40 did not have the necessary reliability. As a result, at the beginning of 1944 the aircraft was converted to a 14-cylinder air-cooled engine Mitsubishi MK8R "Kinsei" -62 with a capacity of 1560 hp. The first Kinsei-powered aircraft was produced in May 1944. Despite the large "forehead" of the radial engine, the increase in air resistance was minimized by installing side fairings on the fuselage behind the hood, so that flight characteristics remained practically unchanged. The second D4Y3, along with 91 D4Y2s, was released in June 1944, but the next month production began to switch to a version for the Kensei engine. Thus, in July and August 1944, 10 and 61 aircraft of this type were delivered, respectively, compared with 83 and 9 aircraft powered by Atsuta engines for the same periods. By September 1944, only D4Y3 remained in production (pictured above), and the peak of production of this aircraft was reached in December of the same year - 106 D4Y. The aircraft was produced at Aichi and the first arsenal in two versions: the "Susay" naval bomber model 33 (D4Y3) and the "ZZA model" (D4Y3a) - the latter had a 13-mm machine gun on a mobile installation. The latest production aircraft were also equipped with three launch rocket boosters for takeoff from small aircraft carriers.

The defeat of the Japanese in the Mariana Islands and the Philippines, where almost all aircraft carriers were lost, forced to make changes to the Susay again. During the fighting for the Philippines, a significant number of D4Ys were used as kamikaze aircraft. Since the Japanese fleet was left without aircraft carriers, a special single-seat version of the Susei for the kamikaze - D4Y4 - was developed at Aichi. The radio operator's place was removed, the lantern above it was closed, and the plane could carry an 800-kg bomb in a semi-drowned position. Since February 1945, the D4Y4 or "Special Marine Attack Bomber Sussei Model 43" has been replaced on the Aichi assembly line in Ettoki D4Y3.

It was planned to produce the "Susi model 54" (D4Y5) naval aircraft carrier bomber under the Nakajima NK9C "Homare" air-cooled engine with a capacity of 1825 hp. It was supposed to install armor protection for the crew and protected tanks, but until the end of the war, the experienced D4Y5 was never completed. A total of 2,038 D4Ys were built: by the 1st Arsenal in Yokosuka - 5 experimental vehicles, Aichi - 6 D4Y1s for military trials, 660 D4Y1 and D4Y1-C; 320 D4Y2 and D4Y2-C, 536 D4Y3, 296 D4Y4, and by the 11th Arsenal plant in Hiro - 215 D4Y1, D4Y2 and D4Y3.

Photo	Description
	Drawing D4Y2
	Yokosuka D4Y1 Suisei at the airfield

Bibliography

• "Encyclopedia of military engineering " /Aerospace Publising/
• "Japan Warplanes of World War II" /Oleg Doroshkevich/