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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
  • Kawanishi H8K Emily flying boat
  • Kawanishi H8K-1 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. To many, the H8K was the best flying boat used in World War II.

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.

The original design had retractable floats and a dorsal turret.

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

Construction

The H8K was of all metal construction.

Crew

The crew was protected by armor.

Wing

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

There were eight small fuel tanks located in the wings.

Fuel Tanks

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

Prototype

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

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

The hull depth was increased by 1' 7.6875" / 5 cm and longitudinal steps were added.

Production

The first production H8K1 flew in August 1941.

  • Kawanishi H8K1 Prototype: 1
    • Production: December 1940
  • Kawanishi H8K1 Pre-Production: 2
    • Production: 1941
  • Kawanishi H8K1: 14, 16, 17
    • Production: 1941 - 1942
  • Kawanishi H8K2: 112, 120
    • Production: 1943 - 1945
  • Kawanishi H8K2-L: 36
    • Production: 1943 - 1945
  • Kawanishi H8K3, Kawanishi H8K3 Prototype: 2
    • Production: 1944
  • Kawanishi H8K4 Prototype: 2 H8K3 airframes modified
    • Production: 1945
  • Total: 167, 175
    • Manufacturer: Kawanishi Kokuki K.K. at Naruo and Konan
    • Production: 1941 - 1945

Variants

  • Kawanishi H8K ??: VIP transport version. Could carry 29 passengers.
  • Kawanishi H8K1, Navy Type 2 Flying Boat Model 11: First production version. Had armor and self sealing fuel tanks.
  • Kawanishi H8K2, Navy Type 2 Flying Boat Model 12: Used more powerful engines with water injection. The armament was increased. The vertical tail surfaces were modified. Starting in 1943 a few had ASV (air surface vessel) radar installed.
  • Kawanishi H8K2-L Seika (Clear Sky): Transport version that could carry 64 passengers. Had Mitsubishi MK4Q engines and not as many weapons. The engines drove Hamilton propellers. Some of the hull fuel tanks were removed to make space for a deck cabin.
  • Kawanishi H8K3: Had additional armor protection. The wing tip floats were retractable. Sliding hatches replaced the gun blisters. The dorsal turret was made to retract.
  • Kawanishi H8K4 Model 23: Was the H8K3 modified by fitting Kasei 25b engines.

Usage

The H8K entered service in early 1942. 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. Cloud cover prevented any good results but it did show the aircraft's potential.

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

Units

  • Kokutais: 14th, 801st, 851st, 1001st, 1021st, Takuma, Toko, Yokohama, Yokosuka Chinjufu

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, 1942). The H8Ks had to refuel by rendezvousing with a submarine at French Frigate Shoals. Cloud cover caused the raid to be a failure.

Anit-Submarine

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

Specifications

  Kawanishi H8K
Type Reconnaissance flying boat
Crew 10
Engine (Type) 4: Mitsubishi MK4A Kasei 11
Cylinders Radial 14
Cooling Air
Net HP 1,530 each
Fuel capacity 3,749 gallons, 4,250 gallons
17,040 liters
Armament  
Turret - Bow 1: 20 mm, 20 mm Type 99 Model 1
Turret - Dorsal 1: 20 mm, 20 mm Type 99 Model 1
Turret - Tail 1: 20 mm, 20 mm Type 99 Model 1
Beams 2: 20 mm
Cockpit 1: 7.7 mm MG
Beam Hatches 2: 7.7 mm MG, 7.7 mm Type 92 MG
Bombs 4,408 lb
2,000 kg
OR  
Torpedoes 2: 1,764 lb
2: 800 kg
  Kawanishi H8K1
Type Reconnaissance
Crew 10
Engine (Type) 4: Mitsubishi MK4B Kasei 12
OR 4: Mitsubishi Kasei 11, Mitsubishi MK4A Kasei 11
Cylinders Radial 14
Net HP 1,530 each
Propeller blades 4 each, 4 metal
Dimensions  
Span 124' 8.0625"
38 m
Length 92' 3.9375"
28.13 m
Height 30' 0.25"
9.15 m
Wing area 1,722.219 sq ft
160 sq m
Weight  
Empty 34,000 lb, 34,176 lb
15,422 kg, 15,502 kg
Loaded 54,013 lb
24,500 kg
Loaded - Maximum 68,343 lb
31,000 kg
Performance  
Speed 269 mph
433 kph
Speed at 16,405' / 5,000 m 269 mph
Speed - Cruising at 13,125' / 4,000 m 184 mph
Climb to 16,405' / 5,000 m 14 minutes 33 seconds
Service Ceiling 25,035'
7,630 m
Range 4,475 miles
Armament 2: 20 mm
4: 7.7 mm / 0.303" MG
Turret - Bow 1: 7.7 mm Type 92 MG
Turret - Dorsal 1: 20 mm Type 99 Model 1
Turret - Tail 1: 20 mm Type 99 Model 1
Beam Blisters 2: 7.7 mm Type 92 MG
Ventral Hatch 1: 7.7 mm Type 92 MG
Cockpit Hatch 1: 7.7 mm Type 92 MG
Torpedoes 2: 1,764 lb
2: 800 kg
OR  
Bombs 8: 551 lb
8: 250 kg
OR  
Depth Charges or Bombs 16: 132 lb
16: 60 kg
  Kawanishi H8K2
Type Flying boat, Reconnaissance
Crew 10
Engine (Type) 4: Mitsubishi Kasei 22 piston
4: Mitsubishi MK4Q Kasei 22
Cylinders Radial 14
Cooling Air
Net HP 1,850 each
Propeller blades 4 each, 4 metal
Fuel capacity 4,154 gallons
18,880 liters
Dimensions  
Span 124' 8", 124' 8.0625"
38 m
Length 92' 3", 92' 3.5", 92' 3.9375", 92' 4"
28.13 m, 28.14 m
Height 30', 30' 0.25"
9.14 m, 9.15 m
Wing area 1,141 sq ft, 1,722 sq ft, 1,722.219 sq ft
106 sq m, 160 sq m
Weight  
Empty 40,520 lb, 40,521 lb
18,360 kg, 18,380 kg
Loaded 54,013 lb
24,500 kg
Loaded - Maximum 71,650 lb
32,500 kg
Performance  
Speed 290 mph
467 kph
Speed at 16,400' / 5,000 m 290 mph
467 kph
Speed at 16,405' / 5,000 m 290 mph
Speed - Cruising 185 mph
298 kph
Speed - Cruising at 13,125' / 4,000 m 184 mph
Climb 1,575'/minute
480 m/minute
Climb to 13,120' / 4,000 m 8 minutes
Climb to 16,405' / 5,000 m 10 minutes 12 seconds
Service ceiling 28,740', 29,035'
8,760 m, 8,850 m
Range 3,000 miles, 4,445 miles
4,828 km
Maximum range 4,460 miles, 4,461 miles
7,777 km, 7,180 km
Armament 5: 20 mm
5: MG
Turret - Bow 1: 20 mm, 20 mm Type 99 Model 1
Turret - Dorsal 1: 20 mm, 20 mm Type 99 Model 1
Turret - Tail 1: 20 mm, 20 mm Type 99 Model 1
Beam Hatches 2: 20 mm, 20 mm Type 99 Model 1
Beam hatches 4: 7.7 mm MG
Ventral, Port, Starboard Sides, Cockpit Hatch 4: 7.7 mm Type 92 MG
Bombs 4,400 lb, 4,409 lb
8: 551 lb
2,000 kg
8: 250 kg
OR  
Torpedoes 2: 1,760 lb, 1,764 lb
2: 800 kg
OR  
Depth Charges or Bombs 16: 132 lb
16: 60 kg
  Kawanishi H8K2-L
Type Transport
Crew 9
Passengers 29
Soldiers 64
Engine (Type) 4: Mitsubishi Mk4Q Kasei 22
Cylinders Radial 14
Cooling Air
Net HP 1,850 each
Propeller blades 4 metal
Fuel capacity 2,951 gallons
13,414 liters
Dimensions  
Span 124' 8.0625"
38 m
Length 92' 3.9375"
28.13 m
Height 30' 0.25"
9.15 m
Wing area 1,722.219 sq ft
160 sq m
Weight  
Empty 37,258 lb
16,900 kg
Loaded 58,826 lb
26,683 kg
Loaded - Maximum 66,139 lb
30,000 kg
Performance  
Speed at 13,125' / 4,000 m 261 mph
Speed - Cruising at 13,125' / 4,000 m 184 mph
Climb to 13,125' / 4,000 m 10 minutes 37 seconds
Range 2,759 miles
Armament 1: 20 mm
1: 12.7 mm MG
Turret - Nose 1: 13 mm Type 2 MG
Turret - Tail 1: 20 mm Type 92 Model 1
  Kawanishi H8K3
Type Flying boat, Reconnaissance
Crew 10
Engine (Type) 4: Mitsubishi Mk4Q Kasei 22
Cylinders Radial 14
Cooling Air
Net HP 1,850 each
Propeller blades 4 metal
Fuel capacity  
Dimensions  
Span 124' 8.0625"
38 m
Length 92' 3.9375"
28.13 m
Height 30' 0.25"
9.15 m
Wing area 1,722.219 sq ft
160 sq m
Weight  
Empty 40,940 lb
18,570 kg
Loaded 54,013 lb
24,500 kg
Loaded - Maximum 71,650 lb
32,500 kg
Armament  
Turret - Bow 1: 20 mm Type 99 Model 1
Turret - Dorsal 1: 20 mm Type 99 Model 1
Turret - Tail 1: 20 mm Type 99 Model 1
Ventral, Port, Starboard Sides, Cockpit Hatch 4: 7.7 mm Type 92 MG
Beam Hatches 2: 20 mm Type 99 Model 1
Bombs 8: 551 lb
8: 250 kg
OR  
Torpedoes 2: 1,764 lb
2: 800 kg
OR  
Depth Charges or Bombs 16: 132 lb
16: 60 kg
  Kawanishi H8K4
Type Flying boat, Reconnaissance
Crew 10
Engine (Type) 4: Mitsubishi Mk4T-B Kasei 25b
Cylinders Radial 14
Cooling Air
Net HP 1,825 each
Propeller blades 4 metal
Armament  
Turret - Bow 1: 20 mm Type 99 Model 1
Turret - Dorsal 1: 20 mm Type 99 Model 1
Turret - Tail 1: 20 mm Type 99 Model 1
Ventral, Port, Starboard Sides, Cockpit Hatch 4: 7.7 mm Type 92 MG
Beam Hatches 2: 20 mm Type 99 Model 1
Bombs 8: 551 lb
8: 250 kg
OR  
Torpedoes 2: 1,764 lb
2: 800 kg
OR  
Depth Charges or Bombs 16: 132 lb
16: 60 kg

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
  4. The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
  5. Japanese Aircraft of the Pacific War, René J Francillon, 1970
20th Century American Military History Crucial Site