Yokosuka P1Y

P1Y Ginga
Role	Attack bomber
National origin	Empire of Japan
Manufacturer	Yokosuka (3 × prototype only); Nakajima; Kawanishi (P1Y2 series only)
First flight	August 1943
Introduction	October 1944
Retired	1945
Primary user	Imperial Japanese Navy Air Service
Number built	1,102

The Yokosuka P1Y Ginga (銀河, "Galaxy") was a twin-engine, land-based bomber developed for the Japanese Imperial Navy in World War II. It was the successor to the Mitsubishi G4M and given the Allied reporting name "Frances".

Design and development edit

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]

Operational history edit

Yokosuka P1Y "Frances" shot down next to USS Ommaney Bay (CVE-79) by 0945 on December 15, 1944.^[4]

The first flight was in August 1943. Nakajima manufactured 1,002 examples, which were operated by five Kōkūtai (Air Groups), and acted as land-based medium and torpedo bombers from airfields in China, Taiwan, the Mariana Islands, the Philippines, the Ryukyu Islands, Shikoku, and Kyūshū. During the last stages of the war the P1Y was used as a kamikaze aircraft against the United States Navy during the Okinawa Campaign in Operation Tan No. 2.

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 edit

P1Y1 prototype #3 Ko-P1-3, Ishikawajima Tsu-11 testbed in 1944.

P1Y1b, Yokosuka Kōkūtai Yo-206.

P1Y1c, since it has a single forward cannon, and no dorsal turret.

A P1Y1 under attack by United States Navy aircraft and anti-aircraft guns.

^[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.

: Mounted Homare 12, and fitted 1 × 13 mm (.51 in) Type 2 machine gun in the back defensive position.

: Converted from P1Y1a, mounted Homare 12, and fitted 2 × 13 mm (.51 in) Type 2 machine guns in the back defensive position.

: 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.

: 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.

: 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]

: Land based bomber. Converted from P1Y2-S. Mounted 1,380 kW (1,850 hp) Mitsubishi MK4T-A Kasei 25 Kō engines.

: Converted from P1Y1a. Mounted Mitsubishi MK4T-A Kasei 25 Kō engines.

: Converted from P1Y1b. Mounted Mitsubishi MK4T-A Kasei 25 Kō engines.

: Converted from P1Y1c. Mounted Mitsubishi MK4T-A Kasei 25 Kō engines.

: 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.
Test production Tenga (試製天河, Shisei Tenga): Proposed jet-powered bomber variant, mounted Ishikawajima Ne-30. Discontinued in 1945.
MXY10 Yokosuka Navy Bomber Ginga: Ground decoy non-flying replica of Yokosuka P1Y1.

Number built by Nakajima and Kawanishi edit

^[11]

	January	February	March	April	May	June	July	August	September	October	November	December	Sub total
1943								2	4	4	10	25	45
1944	11	20	35	46	46	51	47	48	69	75	88	84	620
1945	90	52	52	63	64	53	40	20					434

Operators edit

Japan

Imperial Japanese Navy Air Service^[12]^[13]^[14]^[15]
- 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 edit

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) edit

3-view silhouette of the Yokosuka P1Y

Data from Japanese 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)
Range: 5,370 km (3,340 mi, 2,900 nmi)
Service ceiling: 9,400 m (30,800 ft)
Wing loading: 191 kg/m² (39 lb/sq ft)
Power/mass: 0.20 kW/kg (0.12 hp/lb)

Armament

Guns:

1× flexible, nose-mounted 20 mm (0.787 in) Type 99 cannon
1× flexible rear-firing 13 mm (0.512 in) Type 2 machine gun

Bombs:

up to 1,000 kg (2,205 lb) of bombs or 1× 800 kg (1,764 lb) torpedo

References edit

Notes edit

^ Norman Polmar, Thomas B. Allen, World War II: America at war, 1941–1945, Random House, 1991, p. 310.
^ Francillon 1979, p. 462.
^ Hood, Christopher P. (2007). Shinkansen – From Bullet Train to Symbol of Modern Japan. Routledge, London. pp. 53. ISBN 978-0-415-32052-8.
^ USS Natoma Bay (CVE-62) Logbook Project
^ Francillon 1979, p. 468.
^ Francillon 1979, p. 465.
^ The Maru Mechanic (1984), pp. 109–110.
^ Famous Airplanes of the World (2000), pp. 29–31.
^ Famous Airplanes of the World (2000), p. 26.
^ Model Art (2001), p. 50–53
^ ^a ^b Famous Airplanes of the World (2000), p. 31
^ Francillon 1979, p. 467.
^ The Maru Mechanic (1984), p. 110
^ Model Art (1993), p. 135
^ Famous Airplanes of the World (2000), p. 32–38
^ "Garber Artifacts". www.enginehistory.org. Retrieved 2020-07-06.
^ Francillon 1979, pp. 467–468.

Bibliography edit

Francillon, René J. (1979). Japanese Aircraft of the Pacific War (2nd ed.). London: Putnam & Company. ISBN 0-370-30251-6.
Huggins, Mark (January–February 2004). "Hunters over Tokyo: The JNAF's Air Defence of Japan 1944–1945". Air Enthusiast (109): 66–71. ISSN 0143-5450.