Yokosuka D4Y

https://en.wikipedia.org/wiki/Yokosuka_D4Y

The Yokosuka (???) D4Y Suisei (?? "Comet") Navy Carrier dive bomber was operated
by the Imperial Japanese Navy. Its Allied reporting name was "Judy". The D4Y was
one of the fastest dive bombers of the war and only the delays in its
development hindered its service while its predecessor, the slower fixed-gear
Aichi D3A, remained in service much longer than intended. Despite limited use,
the speed and the range of the D4Y were nevertheless valuable, and the type was
used with success as reconnaissance aircraft as well as for kamikaze missions.

Development of the aircraft began in 1938 at the Yokosuka Naval Air Technical
Arsenal as a carrier-based dive bomber to replace the Aichi D3A. The aircraft
was a single-engine, all-metal low-wing monoplane, with a wide-track retractable
undercarriage and wing-mounted dive brakes. It had a crew of two: a pilot and a
navigator/radio-operator/gunner, seated under a long, glazed canopy which
provided good all-round visibility. The pilot of bomber versions was provided
with a telescopic bombsight. The aircraft was powered by an Aichi Atsuta
liquid-cooled inverted V12 engine, a licensed copy of the German DB 601, rated
at 895 kW (1,200 hp). The radiator was behind and below the three-blade
propeller, as in the P-40 Warhawk.

The aircraft had a slim fuselage that enabled it to reach high speeds in
horizontal flight and in dives, while it had excellent maneuverability despite
high wing loading, with the Suisei having superior performance to contemporary
dive bombers such as the Curtiss SB2C Helldiver. In order to conform with the
Japanese Navy's requirement for long range, weight was minimized by not fitting
the D4Y with self-sealing fuel tanks or armour. In consequence, the D4Y was
extremely vulnerable and tended to catch fire when hit.

Early versions of the D4Y were difficult to keep operational because the Atsuta
engines were unreliable in front-line service. From the beginning, some had
argued that the D4Y should be powered by an air-cooled radial engine which
Japanese engineers and maintenance crew had experience with, and trusted. The
aircraft was re-engined with the reliable Mitsubishi MK8P Kinsei 62, a
14-cylinder two-row radial engine as the Yokosuka D4Y3 Model 33.

The last version was the D4Y4 Special Strike Bomber, a single-seat kamikaze
aircraft, capable of carrying one 800 kg (1,760 lb) bomb, which was put into
production in February 1945. It was equipped with three RATO boosters for
terminal dive acceleration. This aircraft was an almost ideal kamikaze model: it
had a combination of speed (560 km/h/350 mph), range (2,500 km/1,550 mi) and
payload (800 kg/1,760 lb) probably not matched by any other Japanese aircraft.


Role
Dive bomber

Manufacturer
Yokosuka

First flight
December 1940

Introduction
1942

Retired
1945

Primary user
Imperial Japanese Navy Air Service

Produced
1942–1945

Number built
2,038

Lacking armor and self-sealing fuel tanks, the Suiseis did not fare well against
Allied fighters. They did, however, cause considerable damage to ships,
including the carrier USS Franklin which was nearly sunk by an assumed single
D4Y and the light carrier USS Princeton which was sunk by a single D4Y.

The D4Y was operated from the following Japanese aircraft carriers: Chitose,
Chiyoda, Hiyo, Junyo, Shinyo, Shokaku, Soryu, Taiho, Unryu, Unyo and Zuikaku.

The D4Y1-C reconnaissance aircraft entered service in mid-1942, when two of
these aircraft were deployed aboard Soryu at the Battle of Midway, both of which
were lost when Soryu was sunk.

Task Force 58 approached southern Japan in March 1945 to strike military
objectives in support of the invasion of Okinawa. The Japanese responded with
massive kamikaze attacks, codenamed Kikusui, in which many D4Ys were used. A
dedicated kamikaze version of the D4Y3, the D4Y4 with a non-detachable 800 kg
bomb attached in a semi-recessed manner, was developed. The Japanese had begun
installing rocket boosters on some Kamikazes, including the D4Y4 in order to
increase speed near the target. As the D4Y4 was virtually identical in the air
to the D4Y3, it was difficult to determine the sorties of each type.

Carriers USS Enterprise and Yorktown were damaged by D4Ys of 701 Wing on 18
March. On 19 March, the carrier USS Franklin was hit with two bombs from a
single D4Y, which then escaped despite heavy anti-aircraft fire. Franklin was so
heavily damaged that she was retired until the end of the war. Another D4Y hit
the carrier USS Wasp.

On 12 April 1945, another D4Y, part of Kikusui mission N.2, struck Enterprise,
causing some damage.

During Kikusui N.6, on 11 May 1945, USS Bunker Hill was hit and put out of
action by two kamikazes that some sources identify as D4Ys. This was the third
Essex-class carrier forced to retire to the United States to repair.

Specifications (D4Y2)

General characteristics
Crew: two (pilot & gunner/radio operator)
Length: 10.22 m (33 ft 6 in)
Wingspan: 11.50 m (37 ft 9 in)
Height: 3.74 m (12 ft 3 in)
Wing area: 23.6 m² (254 ft²)
Empty weight: 2,440 kg (5,379 lb)
Loaded weight: 4,250 kg (9,370 lb)
Powerplant: 1 × Aichi Atsuta AE1P 32 liquid-cooled inverted V12 piston engine,
1,400 hp (1,044 kW)

Performance
Maximum speed: 550 km/h (342 mph)
Range: 1,465 km (910 mi)
Service ceiling: 10,700 m (35,105 ft)
Rate of climb: 14 m/s (2,700 ft/min)
Wing loading: 180 kg/m² (37 lb/ft²)
Power/mass: 0.25 kW/kg (0.15 hp/lb)

Armament

2× forward-firing 7.7 mm Type 97 aircraft machine guns
1× rearward-firing 7.92 mm Type 1 machine gun
500 kg (1,102 lb) of bombs (design), 800 kg (1,764 lb) of bombs (kamikaze)




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