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Japan's Imperial Navy flag

Japan's Kawanishi H8K; Type 2 Flying Boat Model 11
Allied code name: Emily

Photos

Kawanishi H8K, "Emily" flying boat:
Japan's Kawanishi H8K, "Emily" flying boat

Design

In 1938 a requirement was given for a four engine reconnaissance flying boat superior than the United Kingdom's Short Sunderland.1,2 To many, the H8K was the best flying boat used in World War II.3

Specifications for the H8K called for an aircraft that could fly 5,000 miles at 210 mph and have a maximum speed of 280 mph.3

The original design had retractable floats and a dorsal turret.1

A mission for the H8K could last up to 24 hours.2

Crew

The crew was protected by armor.1

Wing

The wings were made from a metal frame and covering.1 There was a slight dihedral for better stability on long flights.1

There were eight small fuel tanks located in the wings.3

Fuel Tanks

There were six fuel tanks that were located in the hull and were self sealing with carbon dioxide fire supression.1,2,3 The fuel was about 1/3 the total weight at takeoff.3

Prototype

In January 1941 the prototype first flew.1,3
On December 31, 1940 the prototype first flew.2

The prototype had problems with handling on the water.2,3 To correct these issues a second step in the hull was added and changes to the flaps were made.2,3

Production

The first production H8K1 flew in August 1941.2

  • Kawanishi H8K1: 143, 172
  • Kawanishi H8K2: 1123, 1202
  • Kawanishi H8K2-L: 362,3
  • Kawanishi H8K3: 22
  • Total: 1671,3, 1752
    • Manufacturer: Kawanishi Kokuki K.K.3
    • Production: 1941 - 19453

Variants

  • Kawanishi H8K ??: VIP transport version.1 Could carry 29 passengers.1
  • Kawanishi H8K2-L Seika (Clear Sky): Transport version that could carry 64 passengers.1,2,3 Had Mitsubishi MK4Q engines and not as many weapons.1 The engines drove Hamilton propellars.1
  • Kawanishi H8K1: First production version.2
  • Kawanishi H8K2: Used more powerful engines.2 The armament was increased.2 Starting in 1943 a few had ASV (air surface vessel) radar installed.2
  • Kawanishi H8K3: Had additional armor protection.2 The wing tip floats were retractable.2
  • Kawanishi H8K4: Was the H8K3 modified by fitting Kasei 25b engines.2

Usage

The H8K entered service in early 1942.2 The first mission was to have two H8K1s fly from the Marshall Islands and bomb Oahu on the night of March 4 to 5, 1942.3 Cloud cover prevented any good results but it did show the aircraft's potential.3

Allied fighter pilots proceeded with caution when attacking a H8K due to it's heavy armament.2 As a result it was nicknamed the "flying porcupine."3

Pearl Harbor Bombed

The first mission the Kawanishi H8K was used on was a bombing mission that started at Wake Island and bombed Pearl Harbor in 1942 (March 4-5, 19422).1 The H8Ks had to refuel by rendezvousing with a submarine.2

Anit-Submarine

North of the Philippines, in 1945 three American submarines were sunk by radar equipped Kawanishi H8Ks.1

Specifications

  Kawanishi H8K2
Type Reconnaissance flying boat2
Crew 102
Engine (Type)  
Cylinders  
Cooling  
Net HP  
Propeller blades  
Fuel capacity 4,250 gallons3
Dimensions  
Span  
Length  
Height  
Wing area  
Weight  
Empty  
Loaded  
Performance  
Speed  
Speed @ 16,400' /
5,000 m
 
Speed @ 16,405'  
Cruising speed  
Climb  
Climb to 13,120' /
4,000 m
 
Service ceiling  
Range  
Maximum range  
Armament  
Bow turret 1: 20 mm2
Dorsal turret 1: 20 mm2
Tail turret 1: 20 mm2
Beams 2: 20 mm2
Cockpit 1: 7.7 mm MG2
Beam hatches 2: 7.7 mm MG2
Bombs 4,408 lb2
2,000 kg2
OR  
Torpedoes 2: 1,764 lb2
2: 800 kg2
  Kawanishi H8K12
Type  
Crew  
Engine (Type) 4: Mitsubishi MK4B Kasei 122
Cylinders Radial 142
Cooling  
Net HP  
Propeller blades 4 each2
Fuel capacity  
Dimensions  
Span  
Length  
Height  
Wing area  
Weight  
Empty 34,000 lb2
15,422 kg2
Loaded 68,343 lb2
31,000 kg2
Performance  
Speed  
Cruising speed  
Climb  
Service ceiling  
Range  
Maximum range  
Armament  
  Kawanishi H8K21,2,3
Type Flying boat1, Reconnaissance1,3
Crew 101,3
Engine (Type) 4: Mitsubishi Kasei 22 piston1
4: Mitsubishi MK4Q Kasei 222,3
Cylinders Radial 141,3
Cooling Air3
Net HP 1,850 each1,3
Propeller blades 4 each1,2
Fuel capacity  
Dimensions  
Span 124' 8"1,2,3
38 m1,2
Length 92' 3"1, 92' 4"2,3
28.13 m1, 28.14 m2
Height 30'1,2,3
9.14 m2, 9.15 m1
Wing area 1,141 ft2 1
106 m2 1
Weight  
Empty 40,520 lb1, 40,521 lb2
18,360 kg1,2
Loaded 54,013 lb3, 71,650 lb1,2
32,500 kg1,2
Performance  
Speed 290 mph1
467 kph1
Speed @ 16,400' /
5,000 m
290 mph2
467 kph2
Speed @ 16,405' 290 mph3
Cruising speed 185 mph2
298 kph2
Climb 1,575'/minute2
480 m/minute2
Climb to 13,120' /
4,000 m
8 minutes2
Service ceiling 28,740'1,2, 29,035'3
8,760 m1,2
Range 3,000 miles2, 4,445 miles3
4,828 km2
Maximum range 4,460 miles2, 4,461 miles1
7,777 km2, 7,180 km1
Armament 5: 20 mm3
5: MG3
Bow turret 1: 20 mm1
Dorsal turret 1: 20 mm1
Tail turret 1: 20 mm1
Beams 2: 20 mm1
Beam hatches 4: 7.7 mm MG1
Bombs 4,400 lb1,3
2,000 kg1
OR  
Torpedoes 2: 1,760 lb1
2: 800 kg1
  Kawanishi H8K2-L2
Type  
Crew  
Engine (Type)  
Cylinders  
Cooling  
Net HP  
Propeller blades  
Fuel capacity  
Dimensions  
Span  
Length  
Height  
Wing area  
Weight  
Empty  
Loaded  
Performance  
Speed  
Cruising speed  
Climb  
Service ceiling  
Range  
Maximum range  
Armament 1: 20 mm2
1: 12.7 mm MG2

Sources:

  1. Aircraft of World War II, General Editor: Jim Winchester, 2004
  2. Aircraft of WWII, Stewart Wilson, 1998
  3. World War II Airplanes Volume 2, Enzo Angelucci, Paolo Matricardi, 1976
20th Century American Military History Crucial Site