The P1Y was designed by the Yokosuka Naval Air Technical Arsenal to Navy specification 15-Shi,[2] calling for a fast bomber with speed matching the Zero, range matching the G4M, a 907 kg (2,000 lb) bombload, and the ability to dive-bomb as well as carry torpedoes. As the result, the construction suffered from excess complexity, difficulty of manufacture, and poor serviceability. Problems with the availability of enough reliable Nakajima Homare engines led to their replacement by the Mitsubishi Kasei in the P1Y2-S night-fighter version.
The streamlined design of the Ginga is attributed to Miki Tadanao, an engineer who after World War II went on to create a similar aerodynamic design for Japan's earliest bullet trains (Shinkansen), while working with the Japan National Railways (JNR).[3]
A night fighter version, the P1Y2-S Kyokko (極光, "Aurora"), with Mitsubishi Kasei engines, was equipped with radar and Schräge Musik-style upward-firing as well as forward-firing 20 mm cannon. A total of 96 were produced by Kawanishi,[5] but due to inadequate high-altitude performance against the B-29 Superfortress, many were converted back to Ginga bombers.[6]
Variants
[7][8]
P1Y1 Experimental Type 15 land-based bomber (15試陸上爆撃機, 15-Shi Rikujō Bakugekiki)
3 of prototypes and 9 of supplementary prototypes[9] with 1,357 kW (1,820 hp) NK9C Nakajima NK9B Homare 11 engines. Prototype #3 was later used for Ishikawajima Tsu-11 testbed.
P1Y1 Ginga ("Milky Way") Model 11 (銀河11型, Ginga 11-gata)
First model of the series. Mounted Homare 11 or Homare 12.
P1Y1a Ginga Model 11A (銀河11甲型, Ginga 11 Kō-gata)
Mounted Homare 12, and fitted 1 × 13 mm (.51 in) Type 2 machine gun in the back defensive position.
P1Y1b Provisional name Ginga Model 11B (仮称銀河11乙型, Kashō Ginga 11 Otsu-gata)
Converted from P1Y1a, mounted Homare 12, and fitted 2 × 13 mm (.51 in) Type 2 machine guns in the back defensive position.
P1Y1c Provisional name Ginga Model 11C (仮称銀河11丙型, Kashō Ginga 11 Hei-gata)
Converted from P1Y1b, mounted Homare 12, and fitted 1 × 13 mm (.51 in) Type 2 machine gun in the forward position, prototype only.
Converted from P1Y1. Armed with 2 × 20 mm Type 99 cannons. Equipped 302nd Kōkūtai only. This is not a naval regulation equipment.
P1Y1-S Provisional name Ginga Model 21 (仮称銀河21型, Kashō Ginga 21-gata)
Night fighter variant. Armed with 4 × 20 mm Type 99 cannons firing obliquely forward, and 1 × 13 mm (.51 in) Type 2 machine gun in the back defensive position. Only a project.
P1Y1 Ground attack variant
Converted from P1Y1/P1Y1a, installed up to 20 × 20 mm Type 99 cannons in the bomb bay for land strikes against B-29 bases in the Marianas. Approx. 30 rebuilt.
P1Y2-S Provisional name Ginga Model 26/Test production Kyokkō ("Aurora") (仮称銀河26型/試製極光, Kashō Ginga 26-gata/Shisei Kyokkō)
Night fighter variant. Initial named Hakkō ("Corona", 白光) in October 1943, renamed Kyokkō in March 1944.[10] Converted from P1Y1/P1Y1a. Fitted Mitsubishi MK4T-A Kasei 25 engines. Armed with 2 × 20 mm Type 99 cannons and 1 × 30 mm Type 5 cannon. Later, almost all were converted to P1Y2. 96 or 97 produced.[11]
P1Y2 Provisional name Ginga Model 16 (仮称銀河16型, Kashō Ginga 16-gata)
Converted from P1Y2. Armed with 2 × 20 mm Type 99 machine guns or 1 × 30 mm Type 5 cannon. Equipped 302nd Kōkūtai only. This is not a naval regulation equipment.
P1Y3 Provisional name Ginga Model 13 (仮称銀河13型, Kashō Ginga 13-gata)
Converted from P1Y1. Mounted Homare 21 engines.
P1Y4 Provisional name Ginga Model 12 (仮称銀河12型, Kashō Ginga 12-gata)
Converted from P1Y1. Mounted Homare 23 engines.
P1Y5 Provisional name Ginga Model 14 (仮称銀河14型, Kashō Ginga 14-gata)
Converted from P1Y1. Mounted Mitsubishi Ha-43 engines.
P1Y6 Provisional name Ginga Model 17 (仮称銀河17型, Kashō Ginga 17-gata)
Converted from P1Y2. Mounted Mitsubishi MK4T-C Kasei 25 Hei engines.
Provisional name Ginga Model 33 (仮称銀河33型, Kashō Ginga 33-gata)
Long-range bomber variant. Crew: 4, bombs= up to 3,000 kg. Only a project.
302nd Kōkūtai: Equipped night fighter variant only.
521st Kōkūtai
522nd Kōkūtai
523rd Kōkūtai
524th Kōkūtai
701st Kōkūtai
706th Kōkūtai
752nd Kōkūtai
761st Kōkūtai
762nd Kōkūtai
763rd Kōkūtai
765th Kōkūtai
1001st Kōkūtai
1081st Kōkūtai
Miyazaki Kōkūtai
Toyohashi Kōkūtai
Yokosuka Kōkūtai
Kogeki 262nd Hikōtai
Kogeki 401st Hikōtai
Kogeki 405th Hikōtai
Kogeki 406th Hikōtai
Kogeki 501st Hikōtai
Kogeki 708th Hikōtai
Surviving aircraft
A P1Y1 survives at the Smithsonian's Paul Garber Facility of its National Air and Space Museum. While only the fuselage has been photographed several times and can be found on the internet, the wings and engines are confirmed to exist.[16] This was one of three P1Ys that were brought back to the United States after World War II for evaluation.
Specifications (P1Y1a)
Data fromJapanese Aircraft of the Pacific War[17]
General characteristics
Crew: 3
Length: 15 m (49 ft 3 in)
Wingspan: 20 m (65 ft 7 in)
Height: 4.3 m (14 ft 1 in)
Wing area: 55 m2 (590 sq ft)
Empty weight: 7,265 kg (16,017 lb)
Gross weight: 10,500 kg (23,149 lb)
Max takeoff weight: 13,500 kg (29,762 lb)
Powerplant: 2 × Nakajima NK9C Homare 12 18-cylinder air-cooled radial piston engines, 1,361 kW (1,825 hp) each for take-off
Performance
Maximum speed: 547 km/h (340 mph, 295 kn) at 5,900 m (19,400 ft)
Cruise speed: 370 km/h (230 mph, 200 kn) at 4,000 m (13,000 ft)