Japan’s fighting Floatplanes! Part 1

When most people think of floatplanes they think of small, ungainly and totally non threatening aircraft such as the Vought OS2U Kingfisher or the Supermarine Walrus. It appears that someone forgot to tell the Japanese that floatplanes are only slow, harmless, aircraft plodding along the water. Hence they fielded some of the highest performance combat floatplanes seen during the Second World War. This article will deal with Japanese floatplane fighters and a follow up will deal with their advanced reconnaissance models.

The Imperial Japanese Navy (IJN) formulated the idea that high performance float equipped fighters could operate from lagoons or improvised shore bases to support landings in the central Pacific and Solomon Islands where no airfields, or few of them, existed. This was also necessary as the Japanese lacked enough heavy earth moving equipment to build new airfields on her recently occupied islands with any speed. This proved to be a weakness of theirs throughout the Pacific War.

To fill this need the IJN requested that Kawanishi design an offensive floatplane fighter capable of providing close air support to landing forces. This would take some time since Kawanishi was starting from scratch, so the navy instructed Nakajima develop a floatplane version of the Mitsubishi A6M2 Zero. The proposal went to Nakajima and not to the Zero’s originator Mitsubishi, since Mitsubishi’s production lines were already full and Nakajima was already building the Zero under contract (Nakajima would eventually build more Zeros than Mitsubishi).

NakaJima A6M2-N “Rufe”

Nakajima’s design team started by using the powerplant, fuselage and wings of an A6M2 Mod.11. They then modified the tail and rudder, as well as adding one main centerline float along with two wing mounted stabilizing floats. Since the addition of the center line float meant that a drop tank could not be carried an extra fuel tank was placed inside of the float. While slower than the fighter version of the Zero (270Mph Vs. 331Mph) it was still fast enough to be formidable and retained much of the original  Zero’s maneuverability. It also retained the two machine guns and two heavy 20mm cannon of the regular Zero fighter. It could also carry a pair of  132 lbs. bombs.

The A6M2-N never partook in any amphibious landings as it entered service shortly after the capture of Rabaul and the Solomon Islands group. Instead they acted as point interceptors due to the lack of Japanese air fields in the Solomon’s. They proved very vulnerable to allied bombing raids, and had trouble mixing it up with the aircraft of the Cactus Air Force flying from Guadalcanal. They could be effective against unescorted bombers, torpedo planes, allied float planes and even PT Boats, but lacked the performance to go toe to toe with US single engined fighters. The “Rufe” as the allied code named it, also saw action in the Aleutian islands battling US and Canadian P-40s and other aircraft. Later the  “Rufe” acted as a lead in trainer for a far more capable warplane, the Kawanishi N1K1 Kyofu.

Kawanishi N1K1 Kyofu “Rex”

The aircraft originally envisioned to fulfill the IJN’s need for an offensive floatplane was the robust N1K1 Kyofu (Mighty Wind) designed by Kawanishi, a company with extensive experience building advanced amphibious aircraft and flying boats. The Kyofu was much larger than the float equipped Zero with a far more powerful 1,530-hp 14 cylinder Kasei engine driving a 3 blade propeller on an extended shaft. This gave the N1K1 a top speed of 304Mph. The N1K1 prototypes had a contra rotating propeller, Kawanishi’s thinking was that this would correct the effects of on-water torque during takeoff. But difficulty with the gearbox caused Kawanishi to use a conventional single shaft propeller arrangement which proved adequate.

The layout of the Kyofu was conventional, being a mid-wing monoplane with a conventional tail and a bubble canopy that provided excellent vision. It was armed with 2 cowl mounted 7.7mm machine guns and 2 wing mounted 20mm cannon and could carry 2 66 lbs bombs, half the bomb load than the smaller A6M2-N.

While the Kyofu was a very promising design,  it was no longer needed by the time it entered service. The IJN no longer needed an offensive floatplane fighter as it was purely on the defensive by late 1943. N1k1s saw service at Balikpapan in Indonesia and later operated out of Like Biwa on mainland Japan, alongside the A6M2-N. No successes or losses attributable to the type can be found in any English language sources (that I am aware of). It was given the allied codename “Rex”. The importance of the N1K1 was that Kawanishi saw that it had a real winner with the airframe of this aircraft and later redesigned it as the land based N1K1-J Shiden. The Shiden and improved Shiden-Kai were among the best Japanese fighters of the Pacific war.

Analysis

The idea of using floatplanes for close air support wasn’t necessarily a bad one. What really undid these aircraft was that they arrived too late on the scene to make a difference and were not as combat effective as their land based counterparts. Also to perform true close air support these aircraft would have needed more potent close support weapons, like heavy bombs,or rockets. Instead all they could carry was a pair of very light bombs.

Some Japanese Navy pilots did prove their mettle in air to air combat with the “Rufe”.  Lt.(jg) Keizo Yamazaki claimed a P-39 in his “Rufe” which was also adorned with markings for 2 more kills scored by other pilots. Also CPO Eitoku Matsunaga flew a “Rufe” adorned with lightning bolts and is alleged to be the highest scoring floatplane pilot of the war with 8 kills. This has been difficult to prove since CPO Mastunaga has not verified these claims and apparently will not discuss the war

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Specification for the A6M2-N

General characteristics

• Length: 10.10 m (33ft 1⅝ in)
• Wingspan: 12.00 m (39 ft 4⅜ in)
• Height: 4.30 m (14ft 1⅜ in)
• Wing area: 22.44 m² (251.4 sq ft)
• Empty Weight: 1,912 kg (4,235 lb)
• Loaded weight: 2,460 kg (5,423 lb)
• Max takeoff weight: 2,880 kg (6,349 lb)
• Powerplant: 1× Nakajima NK1C Sakae 12 air cooled 14 cylinder radial engine, 950 hp (709 kW) at 4,200 m (13,800 ft)

Performance

• Maximun speed: 436 km/h (235 knots, 270.5 mph) at 5,000 m (16,400 ft)
• Cruise speed: 296 km/h (160 knots, 184 mph)
• Range: 1,782 km (963 nmi, 1,107 mi)
• Service ceiling: 10,000 m (32,800 ft)
• Climb to 5,000 m (16,400 ft): 6 min 43 s

Armament

• Guns:
  • 2 × 7.7 mm Type 97  – machine guns in forward fuselage
  • 2 ×20 mm Type 99 cannon  – fixed in outer wings

• Bombs: 2 × 60 kg (132 lb) bombs

Production: 327

Specification for the Kawanishi N1K1 Kyofu

General Charateristics

• Length: 10.50m (34 ft. 9 1/4 in.)
• Wingspan: 12.00m (39 ft. 4 1/2 in.)
  
• Height: 4.75m (15 ft. 7in.)
  
• Wing area: 23.50m squared (252.96 sq ft.)
  
• Empty weight: 2750 kg (6,063 lb.)
  
• Loaded weight: 3,500 kg (7,716 lb.)
• Max takeoff weight: 3710 kg (8,179 lb.)
  
• Powerplant: One 1,530-hp (1141-kW) Mitsubishi MK4E Kasei 15 14-cylinder radial piston engine

Performance

• Maximum Speed: 264 kt at 5,700 m (304 mph at 18,700 ft.)
  
• Cruise speed: 200 kt at 2,000 m (230 mph at 6,500 ft.)
  
• Range: normal 570 naut miles (656 st miles) maximum 900 naut miles (1,036 st miles)
  
• Service Ceiling: 10,560 m (34,645 ft.)
  
• Climb to 5,000 m (16,405 ft.): 5 min. 52 sec.

Armament

• Guns:
• 2x fuselage mounted 7.7 Type 97 machine guns
• 2x wing-mounted 20mm Type 99 Model 1 cannon

• Bombs: 2x 30kg (66 lb.) bombs

Production: 97