Yokosuka D4Y
Unanswered Questions
Encyclopedia
The D4Y Navy Type 2 Carrier Dive bomber
Dive bomber
A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target reduces the distance the bomb has to fall, which is the primary factor in determining the accuracy of the drop...
was operated by the Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...
. Its Allied reporting name
World War II Allied names for Japanese aircraft
The World War II Allied names for Japanese aircraft were reporting names, often described as codenames, given by Allied personnel to Imperial Japanese aircraft during the Pacific campaign of World War II. The names were used by Allied personnel to identify Japanese aircraft for reporting and...
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
Aichi D3A
The , Allied reporting name "Val") was a World War II carrier-borne dive bomber of the Imperial Japanese Navy . It was the primary dive bomber in the Imperial Japanese Navy, and participated in almost all actions, including Pearl Harbor....
remained in service much longer than intended. Despite limited use, the speed and the range of the D4Y was nevertheless valuable, and the type was used with success as reconnaissance aircraft
Reconnaissance aircraft
A reconnaissance aircraft is a manned military aircraft designed, or adapted, to carry out aerial reconnaissance.-History:The majority of World War I aircraft were reconnaissance designs...
as well as for kamikaze
Kamikaze
The were suicide attacks by military aviators from the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy as many warships as possible....
missions.
Design and development
Development of the aircraft began in 1938 at the Yokosuka Naval Air Technical ArsenalYokosuka Naval Air Technical Arsenal
had many names, each depending on the period of its existence, and the circumstances at that time. Many of the names were acronyms that were derived from its military name or designation, which changed from time to time. The arsenal was sometimes known as "Kūgi-shō"...
as a carrier-based
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
dive bomber
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...
to replace the Aichi D3A
Aichi D3A
The , Allied reporting name "Val") was a World War II carrier-borne dive bomber of the Imperial Japanese Navy . It was the primary dive bomber in the Imperial Japanese Navy, and participated in almost all actions, including Pearl Harbor....
.
The aircraft was a single-engine, all-metal low-wing monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...
, with a wide-track retractable undercarriage
Undercarriage
The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...
and wing-mounted dive brake
Air brake (aircraft)
In aeronautics, air brakes or speedbrakes are a type of flight control surface used on an aircraft to increase drag or increase the angle of approach during landing....
s. 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
Bombsight
A bombsight is a device used by bomber aircraft to accurately drop bombs. In order to do this, the bombsight has to estimate the path the bomb will take after release from the aircraft. The two primary forces during its fall are gravity and air drag, which makes the path of the bomb through the air...
. The aircraft was powered by an Aichi Atsuta
Aichi Atsuta
The Aichi Kokuki KK AE1A Atsuta was a Japanese licensed version of the German Daimler-Benz DB 601A 12-cylinder liquid-cooled inverted-vee aircraft engine. The Atsuta powered only two models of Imperial Japanese Navy Air Service aircraft aircraft in World War II...
liquid-cooled inverted V-12 in-line engine, a licenced copy of the German DB 601
Daimler-Benz DB 601
|-See also:-Bibliography:* Mankau, Heinz and Peter Petrick. Messerschmitt Bf 110, Me 210, Me 410. Raumfahrt, Germany: Aviatic Verlag, 2001. ISBN 3-92550-562-8.* Neil Gregor Daimler-Benz in the Third Reich. Yale University Press, 1998-External links:...
, rated at 895 kW (1,200 hp). The radiator
Radiator
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...
was behind and below the three-blade propeller, as in the P-40.
It had a slim, elegant fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
that enabled it to reach high speeds in horizontal flight and in dives, while low wing loading
Wing loading
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing. The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading. Correspondingly,...
gave excellent maneuverability, with the Suisei having superior performance than contemporary dive bombers such as the SB2C Helldiver
SB2C Helldiver
The Curtiss SB2C Helldiver was a carrier-based dive bomber aircraft produced for the United States Navy during World War II. It replaced the Douglas SBD Dauntless in US Navy service. Despite its size, the SB2C was much faster than the SBD it replaced...
. In order to conform with the Japanese Navy's doctrine of ensuring that its aircraft could outrange potential enemies, weight had to be minimized with the result that the D4Y was not fitted with self-sealing fuel tank
Self-sealing fuel tank
In aviation, self-sealing fuel tank is a fuel tank technology in wide use since World War II that prevents fuel tanks primarily on aircraft from leaking fuel and igniting after being damaged by enemy fire....
s or armour
Vehicle armour
Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets, missiles, or shells, protecting the personnel inside from enemy fire. Such vehicles include tanks, aircraft, and ships....
. In consequence, the D4Y was extremely vulnerable and tended to catch fire when hit.
Bombs were fitted under the wings and in an internal bomb bay
Bomb bay
The bomb bay or weapons bay on some military aircraft is a compartment to carry bombs, usually in the aircraft's fuselage, with "bomb bay doors" which open at the bottom. The bomb bay doors are opened and the bombs are dropped when over the target or at a specified launching point.Large-sized...
, something rare in a single-engine aircraft. It carried one 500 kg (1,100 lb) bomb, but there were reports that the D4Y sometimes carried two 250 kg (550 lb) bombs, for example during the attack on the light aircraft carrier
Light aircraft carrier
A light aircraft carrier is an aircraft carrier that is smaller than the standard carriers of a navy. The precise definition of the type varies by country; light carriers typically have a complement of aircraft only ½ to ⅔ the size of a full-sized or "fleet" carrier.-History:In World War II, the...
. Only 30 kg (70 lb) bombs were carried externally. The aircraft was armed with two 7.7 mm (.303 in) machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....
s in the nose, and one 7.92 mm (.312 inm) Type 1 machine gun
Type 1 machine gun
The Type 1 machine gun was developed for aerial use for the Imperial Japanese Army and Navy during World War II. It was an adaptation of the German MG 15 machine gun.-Installations:* Aichi B7A* Mitsubishi Ki-67* Nakajima C6N* Yokosuka D4Y...
in the rear of the cockpit
Cockpit
A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin...
. (The 7.92 mm/.312 in was carried because of its higher rate of fire.) Later, the 7.92 mm (.312 in) was replaced by a 13 mm (.51 in) Type 2 machine gun
Type 2 machine gun
The Type 2 machine gun was developed for aerial use for the Imperial Japanese Navy during World War II. It was an adaptation of the German MG 131 machine gun.-Installations:* Aichi B7A* Mitsubishi A6M5c* Mitsubishi G4M* Nakajima B6N* Yokosuka P1Y...
. This light gun armament was typical for a Japanese carrier-based bomber. The forward machine guns were retained in the kamikaze version.
The first D4Y1 prototype
Prototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...
made its maiden flight in December 1940. After the prototype's successful trials, development continued, and the first problems appeared. During dive-bombing trials, the wings of the D4Y started to flutter, a fatal flaw for an airframe
Airframe
The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...
subject to the stresses of dive bombing. Because of this, initial production aircraft were used as reconnaissance
Reconnaissance
Reconnaissance is the military term for exploring beyond the area occupied by friendly forces to gain information about enemy forces or features of the environment....
aircraft, as the D4Y1-C, which took advantage of its high speed and long range, while not over-stressing the airframe. Production of the D4Y1-C continued in small numbers until March 1943, when the increasing losses incurred by the D3A resulted in production switching to the D4Y1 dive-bomber, the aircraft's structural problems finally being solved. Although the D4Y could operate successfully from the large and fast fleet carriers that formed the core of the Combined Fleet
Combined Fleet
The was the main ocean-going component of the Imperial Japanese Navy. The Combined Fleet was not a standing force, but a temporary force formed for the duration of a conflict or major naval maneuvers from various units normally under separate commands in peacetime....
at the start of the war, it had problems operating from the smaller and slower carriers such as the Hiyō class
Hiyo class aircraft carrier
The were built for the Imperial Japanese Navy during World War II. Both ships of the class were originally laid down as luxury passenger liners before being acquired by the IJN for conversion to aircraft carriers in 1941. Junyō was the first of the sisters to be completed in May 1942 and the ship...
which formed a large proportion of Japan's carrier fleet after the losses received in the Battle of Midway
Battle of Midway
The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...
. Catapult equipment was therefore fitted, giving rise to the D4Y-1 Kai (or improved) model.
Radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders point outward from a central crankshaft like the spokes on a wheel...
, a type Japanese engineers - and maintenance crew - had experience with and trusted. The aircraft was therefore fitted with the reliable Mitsubishi MK8P Kinsei 62
Mitsubishi Kinsei
|-See also:-Bibliography:* Matsuoka Hisamitsu, Nakanishi Masayoshi. The History of Mitsubishi Aero Engines 1915-1945. Miki Press, Japan, 2005. ISBN 4-89522-461-9...
, a 14-cylinder two-row radial engine. This version was the Yokosuka D4Y3 Model 33.
Although the new engine improved ceiling and rate of climb (over 10,000 m/32,800 ft, and climb to 3,000 m/9,800 ft in 4.5 minutes, instead of 9,400 m/30,800 ft and 5 minutes), the higher fuel consumption resulted in shorter range and a slower cruising speed, while the bulky engine obstructed the forward and downward view of the pilot, hampering carrier operations. These problems were tolerated because of the increased availability of the new variant.
The last version was the D4Y4 Special Strike Bomber. This one-seat kamikaze aircraft, capable of carrying one 800 kg (1,760 lb) bomb, was put into production in February 1945. It was equipped with three RATO boosters
JATO
JATO is an acronym for jet-fuel assisted take off. It is a system for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets....
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.
The D4Y5 Model 54 was a planned version designed in 1945. It was to be powered by the Nakajima NK9C Homare 12
Nakajima Homare
|-See also:-Bibliography:* Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1998. ISBN 0-517-67964-7* Gunston, Bill. World Encyclopaedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9...
radial engine rated at 1,361 kW (1,825 hp), would have a new four-blade metal propeller of the constant-speed type, and would have more armour protection for the crew and fuel tanks.
Ultimately, 2,038 of all variants were produced, mostly by Aichi.
Operational history
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
s. They did, however, cause considerable damage to ships, including the carrier , which was nearly sunk by a single D4Y.
The D4Y was operated from the following Japanese aircraft carriers: , , , , , , , , , and .
The D4Y1-C reconnaissance aircraft entered service in mid-1942, when two of these aircraft were deployed aboard Sōryū at the Battle of Midway, where both were lost when Sōryū was sunk.
Marianas
During the Battle of the MarianasBattle of the Philippine Sea
The Battle of the Philippine Sea was a decisive naval battle of World War II which effectively eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War...
, the D4Ys were engaged by U.S. Navy fighters and shot down in large numbers. The D4Y was faster than the Grumman F4F Wildcat, but not the new Grumman F6F Hellcat. The Japanese aircraft were adequate in 1943, but the rapid advances in American materiel
Materiel
Materiel is a term used in English to refer to the equipment and supplies in military and commercial supply chain management....
in 1944 (among them, the introduction in large numbers of the Essex-class aircraft carrier
Essex class aircraft carrier
The Essex class was a class of aircraft carriers of the United States Navy, which constituted the 20th century's most numerous class of capital ships with 24 vessels built in both "short-hull" and "long-hull" versions. Thirty-two were originally ordered; however as World War II wound down, six were...
) left them behind, while their inexperienced pilots were another disadvantage.
The U.S. Task Force 58
Fast Carrier Task Force
The Fast Carrier Task Force was the main striking force of the United States Navy in the Pacific Ocean theatre of World War II.The Fast Carrier Task Force was known under two designations. The Navy made use of two sets of upper command structures for planning the upcoming operations...
struck the Philippine airfields and destroyed the land air forces first, before engaging the Japanese naval aircraft. The result was what the Americans called "The Great Marianas Turkey Shoot", with 400 Japanese aircraft shot down in a single day. A single Hellcat pilot, Lieutenant
Lieutenant
A lieutenant is a junior commissioned officer in many nations' armed forces. Typically, the rank of lieutenant in naval usage, while still a junior officer rank, is senior to the army rank...
Alexander Vraciu
Alexander Vraciu
Alexander Vraciu was a leading United States Navy fighter ace and Congressional Medal of Honor nominee during World War II. He once shot down six Japanese fighters in eight minutes.-Biography:...
, shot down six D4Ys within a few minutes.
Leyte and Philippines
A6M Zero
The Mitsubishi A6M Zero was a long-range fighter aircraft operated by the Imperial Japanese Navy Air Service from 1940 to 1945. The A6M was designated as the , and also designated as the Mitsubishi A6M Rei-sen and Mitsubishi Navy 12-shi Carrier Fighter. The A6M was usually referred to by the...
fighters and D4Ys, with much more damage. D4Ys also made conventional attacks. All these D4Ys were from 601 and 653 Kokutai.
In defence of the homeland
Task Force 58 approached southern Japan in March 1945 to strike military objectives in support of the invasion of OkinawaBattle of Okinawa
The Battle of Okinawa, codenamed Operation Iceberg, was fought on the Ryukyu Islands of Okinawa and was the largest amphibious assault in the Pacific War of World War II. The 82-day-long battle lasted from early April until mid-June 1945...
. The Japanese responded with massive kamikaze attacks, codenamed Kikusui, in which many D4Ys were used.
Carriers and were damaged by D4Ys of 701 Wing on 18 March. On 19 March, the carrier Franklin
USS Franklin (CV-13)
The USS Franklin , nicknamed "Big Ben," was one of 24 s built during World War II for the United States Navy, and the fifth US Navy ship to bear the name. Commissioned in January 1944, she served in several campaigns in the Pacific Theater of Operations, earning four battle stars...
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 .
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, 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 States to repair.
Night fighter
The D4Y was faster than the A6M Zero and some were employed as D4Y2-S night fighterNight fighter
A night fighter is a fighter aircraft adapted for use at night or in other times of bad visibility...
s against Boeing B-29 Superfortress bombers late in the war, an unusual role for a single-engine dive bomber. The night fighter conversions were made at the 11th Naval Aviation Arsenal at Hiro. Each D4Y2-S had bomb equipment removed and a 20 mm Type 99 cannon
Type 99 cannon
The Type 99-1 cannon and Type 99-2 cannon were Japanese versions of the Oerlikon FF and Oerlikon FFL. They were adopted by the Imperial Japanese Navy in 1939 and served as their standard aircraft autocannon during World War II.-Adoption:...
with its barrel slanted up and forwards (similar to the German Schräge Musik
Schräge Musik
Schräge Musik, derived from the German colloquialism for "Jazz Music" was the name given to installations of upward-firing autocannon mounted in night fighters by the Luftwaffe and Imperial Japanese Navy Air Service during World War II, with the first victories for each occurring in May 1943...
) installed in the rear cockpit. However the lack of radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
for night interceptions, low climb rate and the B-29's high ceiling limited the D4Y2-S effectiveness as a night fighter. Little is known of their operations.
Last action
At the end of the war D4Ys were still being used operationally against the U.S. Navy, and among the last of these were 11 aircraft led by Vice AdmiralVice Admiral
Vice admiral is a senior naval rank of a three-star flag officer, which is equivalent to lieutenant general in the other uniformed services. A vice admiral is typically senior to a rear admiral and junior to an admiral...
Matome Ugaki on a search mission on 15 August 1945, of which all but three were lost.
Operators
- Imperial Japanese Navy Air ServiceImperial Japanese Navy Air ServiceThe Imperial Japanese Navy Air Service was the air arm of the Imperial Japanese Navy during World War II, the organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War.It was controlled by the Navy Staff of the Imperial Japanese Navy and...
- 1st Koku Sentai
- 2nd Koku Sentai
- 3rd Koku Sentai
United States
- United States NavyUnited States NavyThe United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
operated captured aircraft for evaluation purposes.
Variants
D4Y1- Prototype and first batch of serial produced dive bomber aircraft. Powered by 895 kW (1,200 hp) Aichi AE1A Atsuta 12 engine.
D4Y1-C
- Reconnaissance version produced at Aichi's Nagoya factory.
D4Y1 KAI
- Dive bomber with aircraft carrier catapult equipment.
D4Y2 Model 12
- 1,044 kW (1,400 hp) Aichi AE1P Atsuta 32 engine adopted.
D4Y2-C
- Reconnaissance version of the D4Y2.
D4Y2 KAI Model 22
- D4Y2 with aircraft carrier catapult equipment.
D4Y2a Model 12A
- D4Y2 with the rear cockpit 13 mm (.51 in) machine gun.
D4Y2-Ca
- Reconnaissance version of the D4Y2a.
D4Y2a KAI Model 22A
- D4Y2a with aircraft carrier catapult equipment.
D4Y2-S Suisei-E
- Night fighter with bomb equipment removed and a 20 mm upward-firing cannon installed.
D4Y3 Model 33
- 1,163 kW (1,560 hp) Mitsubishi KinseiMitsubishi Kinsei|-See also:-Bibliography:* Matsuoka Hisamitsu, Nakanishi Masayoshi. The History of Mitsubishi Aero Engines 1915-1945. Miki Press, Japan, 2005. ISBN 4-89522-461-9...
62 radial engine adopted.
D4Y3a Model 33A
- D4Y3 with the rear cockpit 13 mm (.51 in) machine gun.
D4Y4 Model 43 Special Strike Bomber
- One seat kamikazeKamikazeThe were suicide attacks by military aviators from the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy as many warships as possible....
aircraft with 800 kg (1,760 lb) bomb and three RATO boosters.
D4Y5 Model 54
- Planned version with Nakajima HomareNakajima Homare|-See also:-Bibliography:* Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1998. ISBN 0-517-67964-7* Gunston, Bill. World Encyclopaedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9...
radial engine, four-blade propeller, and more armor protection.
Survivors
A surviving restored D4Y1 (serial 4316) is located at the Yasukuni Jinja YūshūkanYushukan
The is a Japanese military and war museum located within Yasukuni Shrine in Chiyoda, Tokyo. As a museum maintained by the shrine, which is dedicated to the souls of soldiers who died fighting on behalf of the Emperor of Japan, the museum contains various artifacts and documents concerning Japanese...
shrine in Tokyo, and a second example (serial 7483) was recovered from Babo Airfield
Babo Airfield
Babo Airfield is a disused airfield located on the southern shore of Maccluer Gulf at Babo in Indonesia. The airfield is located in an isolated low-lying swamp area.-History:...
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
in 1991 and is currently being restored by the Planes of Fame Air Museum
Planes of Fame
Planes of Fame Air Museum is an aviation museum located in Chino, California, and Valle, Arizona. The museum has many flying and static aircraft, along with multiple rare examples under restoration.-History:...
in Chino, California
Chino, California
Chino is a city in San Bernardino County, California, United States. It is located in the western end of the Riverside-San Bernardino Area and it is easily accessible via the Chino Valley and Pomona freeways....
to non-flying condition as a D4Y3.
Specifications (D4Y2)
