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WWII Aircraft Listings - 3

102-WWII-Yokosuka-D4Y

The Yokosuka D4Y Suisei 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.

Maximum speed: 550.40 km/h (342 mph), Maiden flight: Dec 1940, Length: 33.50 ft, Wingspan: 37.73 ft, Passengers: 2, Retired: 1945

The Yokosuka D4Y Suisei (translating to "Comet" and nicknamed "Judy" by the Allies) was a capable dive bomber serving the Imperial Japanese Navy during the Second World War. The system saw some reliability issues in early presentations and suffered heavy losses at the hands of Allied carrier groups but the system performed admirably well thanks to the performance capabilities inherent in the design - this of course at the expense of crew protection and structural armoring.

The D4Y was a single engine, two-crew dive bomber platform. The Mitsubishi MK8P Kinsei 62 radial piston engine found in the D4Y3 model offered up reliability with performance at 357 miles per hour with a ceiling of nearly 35,000 feet. The crew sat in a long greenhouse-type canopy in tandem. Defensive armament consisted of twin 7.7mm machine guns in a forward-fixed position and a single 13.1mm machine gun in a trainable rear cockpit mounting. External ordnance was limited to 1,235 pounds of stores. Overall, the design concept actually stemmed from the German Heinkel He 118, as Japan purchased manufacturing rights for the German type back in 1938.

The D4Y first flew in late 1942 in its dive bomber form designated simply as the D4Y1. The system then appeared shortly thereafter in a reconnaissance form as the D4Y1-C. Before long, the D4Y series was fielded in quantity across several Japanese carrier groups and would see yet another improved version - known as the D4Y2 - appear. This one being fitted with a Atsuta 32 Aichi-brand 1,400hp engine. It was soon found, however, that the aircraft, though performing well in terms of capability, suffered from reliability problems with the new engine. To add insult to injury, the performance gains brought about by the new powerplant were negated to some extent by the fact that crew and fuel protection was not addressed, leading to heavy losses. The D4Y3 addressed the D4Y2's reliability problems with the introduction of the Mitsubishi MK8P Kinsei 62 radial piston engine. By the end of the war, as with most of the IJN's small airframes, the D4Y was made into a dedicated suicide model. This one, a single-seater, was designated as the D4Y4 and fielded in 1945.

The Yokosuka D4Y Suisei (Comet) is often compared to the British de Havilland Mosquito due to it's developmental history, excellence and versatility. But this is where the similarities end. Let's go back to 1938, the year in which the first actions were taken that finally resulted in this excellent naval dive-bomber, reconnaissance aircraft and night fighter.

Due to the strong resemblance from a political point of view, Japan had already established a good relationship with Germany. Both powers were rapidly expanding their military potential, both had great plans for domination dictated from their belief in their superiority over other peoples and countries surrounding them. Both for Germany and Japan, as well as for Italy, it was only natural that they would rule over their neighbours, since they were "of a superior race". Or so they believed. It is no surprise then that the cooperation between these countries, even though the racial differences were quite great from each others point of view, was reasonable strong as far as military aspects were concerned. This was abundantly clear when Japan was allowed to buy one of the Heinkel He 118 prototypes, the V4. Together with the actual machine Japan bought the rights to develop and build further on the Heinkel He 118 concept.

The German machine achieved a max level speed of 260 mph (418 km/h) during test flight, powered by 1 × Daimler-Benz DB 601Aa inverted-Vee, rated at 1,175 hp (876 kW). Impressed by the potential the aircraft offered, the Japanese Navy immediately planned for a Japanese carrier-borne version of the He 118.

Redesignated according to the Japanese system, the DXHe1 was used until it broke up in mid-flight. Even so, the Navy was consisting in it's plans for their own high speed carrier-borne dive-bomber version of the DXHe1. For this reason the dai-Ichi Kaigun Koku Gijisusho (1st Naval Technical Air Arsenal) was instructed to design a dive-bomber based on the DXHe1, but smaller. The requirements for this type of aircraft were laid out in the 13-Shi Navy experimental Carrier Bomber requirement of 1938, calling for a max level speed of 322 mph (518 km/h), cruising speed of 265 mph (427 km/h), a range of 1,381 miles (2.222 km) without a bomb, and a range of 921 miles (1.482 km) with a bombload of 551 lb (250 kg).

Headed by Masao Yamana, the Yokosuka design team created a clean design for a single-engine mid-wing monoplane dive-bomber with accommodation for two in a long cockpit under a ‘glasshouse’ canopy, a wing that was more or less comparable with that of the Mitsubishi A6M Reisen in span and area (thereby removing the need for a wing-folding system), a fuel capacity almost as large as that of the Aichi D3A that it was to supplant, and a fully retractable tailwheel landing gear. The basic configuration showed resemblance to the DXhe1 prototype of Heinkel, but this D4Y design was smaller, lighter, stronger, more advanced in its structure and aerodynamics, and possessed internal stowage for the 1,102 lb (500 kg) bomb that was its primary armament. Another proof to the German inheritance was the projected powerplant, being 1 × Aichi AE1 Atsuta inverted-Vee piston engine, which was the Japanese license-built derivative of the DB 601. The navy ordered Yokosuka the production of five prototypes each powered by an imported Daimler-Benz DB 600G engine, rate at 960 hp (716 kW) and driving a three-blade metal propeller of the constant-speed type, pending availability of the Atsuta.

Central in it's design, the airframe was an oval-section fuselage of semi-monocoque construction which carried the engine in the nose with its radiator in a bath set slightly back from the nose on the underside of the forward fuselage. This core structure supported the flying surfaces, comprising a cantilever tail unit of metal stressed-skin construction with fabric-covered control surfaces, and the low/mid-set wing. This wing was slightly dihedraled, tapered in thickness and chord, and carried along almost the full span of its trailing edges the standard combination of outboard ailerons and inboard flaps, the latter with electrically operated three-section dive-brakes ahead of them under each wing. The first D4Y1 prototype made its maiden flight in December 1940, and proved to possess an excellent combination of high performance and good handling.

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)

General Characteristics (D4Y2)
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)

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

Operators
A D4Y3 (Type 33) at NAS Anacostia is tested by U.S. Navy personnel of the TAIC (Technical Air Intelligence Center) after the war.
Japan
Imperial Japanese Navy Air Service
Aircraft carrier
Sōryū, equipped prototype #3 and #4.
Shōkaku, supplied from 601st Kōkūtai.
Zuikaku, supplied from 601st Kōkūtai.
Taihō, supplied from 601st Kōkūtai.
Jun'yō, supplied from 652nd Kōkūtai.
Battleship
Ise, supplied from 634th Kōkūtai.
Hyūga, supplied from 634th Kōkūtai.
Naval Air Group
Himeji Kōkūtai
Hyakurihara Kōkūtai
Kaikō Kōkūtai
Kanoya Kōkūtai
Kantō Kōkūtai
Kinki Kōkūtai
Kyūshū Kōkūtai
Nagoya Kōkūtai
Nansei-Shotō Kōkūtai
Ōryū Kōkūtai

Tainan Kōkūtai
Taiwan Kōkūtai
Tōkai Kōkūtai
Tsuiki Kōkūtai
Yokosuka Kōkūtai
12th Kōkūtai
121st Kōkūtai
131st Kōkūtai
132nd Kōkūtai
141st Kōkūtai
151st Kōkūtai
153rd Kōkūtai
201st Kōkūtai
210th Kōkūtai
252nd Kōkūtai
302nd Kōkūtai
352nd Kōkūtai
501st Kōkūtai
502nd Kōkūtai
503rd Kōkūtai
521st Kōkūtai
523rd Kōkūtai
531st Kōkūtai

541st Kōkūtai
552nd Kōkūtai
553rd Kōkūtai
601st Kōkūtai
634th Kōkūtai
652nd Kōkūtai
653rd Kōkūtai
701st Kōkūtai
721st Kōkūtai
722nd Kōkūtai
752nd Kōkūtai
761st Kōkūtai
762nd Kōkūtai
763rd Kōkūtai
765th Kōkūtai
901st Kōkūtai
951st Kōkūtai
1001st Kōkūtai
1081st Kōkūtai
Aerial Squadron
Recon. 3rd Hikōtai
Recon. 4th Hikōtai
Recon. 61st Hikōtai

Recon.101st Hikōtai
Recon.102nd Hikōtai
Attack 1st Hikōtai
Attack 3rd Hikōtai
Attack 5th Hikōtai
Attack 102nd Hikōtai
Attack 103rd Hikōtai
Attack 105th Hikōtai
Attack 107th Hikōtai
Attack 161st Hikōtai
Attack 251st Hikōtai
Attack 263rd Hikōtai

Kamikaze
Chūyū group (picked from Attack 5th Hikōtai)
Giretsu group (picked from Attack 5th Hikōtai)
Kasuga group (picked from Attack 5th Hikōtai)
Chihaya group (picked from 201st Kōkūtai)
Katori group (picked from Attack 3rd Hikōtai)
Kongō group No. 6 (picked from 201st Kōkūtai)
Kongō group No. 9 (picked from 201st Kōkūtai)
Kongō group No. 11 (picked from 201st Kōkūtai)
Kongō group No. 23 (picked from 201st Kōkūtai)
Kyokujitsu group (picked from Attack 102nd Hikōtai)
Suisei group (picked from Attack 105th Hikōtai)
Yamato group (picked from Attack 105th Hikōtai)
Kikusui-Suisei group (picked from Attack 103rd Hikōtai and Attack 105th Hikōtai)
Kikusui-Suisei group No. 2 (picked from Attack 103rd Hikōtai and Attack 105th Hikōtai)
Koroku-Suisei group (picked from Attack 103rd Hikōtai)
Chūsei group (picked from 252nd Kōkūtai and Attack 102nd Hikōtai)
Mitate group No. 3 (picked from Attack 1st Hikōtai and Attack 3rd Hikōtai)
Mitate group No. 4 (picked from Attack 1st Hikōtai)
210th group (picked from 210th Kōkūtai)
Niitaka group (picked from Attack 102nd Hikōtai)
Yūbu group (picked from Attack 102nd Hikōtai)
United States - United States Navy operated captured aircraft for evaluation purposes.

After the prototype's succesful trials development was sped up, but then the first unpleasant surprise came. During dive-bombing trials the wings of the D4Y started to flutter, so much that it could break up the wing spars.

Even though Aichi was already asked to build a construction line for the D4Y, the future was unsure at that time. The task it was designed for, the D4Y was unfit to perform. As an alternative taking into considration it's good performance, ceiling and range, the D4Y was then selected for reconnaissance duties. Therefor the first pre-production batch was adapted for this role, and the Suisei started lifa as a reconnaissance aircraft in stead of a dive bomber