Ki-43 “Oscar”, Japanese Fighter

Photograph of Ki-43 Oscar fighter

U.S. Navy. Via Francillon (1979)

3-view diagram of Ki-43 Oscar

U.S. Army. Via

Nakajima Ki-43-Ia Hayabusa ("Peregrine Falcon") “Oscar”


Dimensions 37'6" by 29'0" by 10'9"
11.43m by 8.84m by 3.28m
Weights 3483-5696 lbs
1580-2584 kg
Wing area 237 square feet
22.0 square meters
Maximum speed       308 mph at 13,125 feet
496 km/h at 4000 meters
Cruise speed 199 mph at 8,200 feet
320 km/h at 2500 meters
Service ceiling 38,500 feet
11,700 meters
Power plant 1 950 hp (708 kW) Nakajima Ha-25 14-cylinder radial engine driving a two-pitch two-bladed Hamilton-type metal propeller.
Armament 7.7mm Type 89 Model 2 machine guns in nose
External stores
2 15 kg (33 lb) bombs under the wings
Fuel capacity
125 gallons
473 liters
Range Maximum 745 miles (1200 km)
Production A total of 5919 Ki-43s were produced as follows:

Nakajima Hikoki K.K. at Ota:
    13 Ki-43 prototypes and service trial (1938-12 to 1940-9)
716 Ki-43-I (1941-4 to 1943-2)
8 Ki-43-II prototypes and service trials (1942-2 to 1942-8)
2492 Ki-43-II (1942-11 to 1944-10)
10 Ki-43-III prototypes (1944-5 to 1945-8)

Tachikawa Hikoki K.K. (Tachikawa)

2629 Ki-43-II and Ki-43-IIIa (1943-5 to 1945-8)
2 Ki-43-IIIb prototypes (1945)

Tachikawa Dai-Ichi Rikugun Kokusho (Tachikawa)

49 Ki-43-IIa (1942-10 to 1943-11)
Variants The Ib replaced one of the 7.7mm nose machine guns with a 12.7mm Type 1 machine gun (250 rounds) and the Ic replaced both.

The IIa introduced 13mm head and back armor for the pilot and rudimentary self-sealing fuel tanks.

The IIb used a Nakajima Ha-115 engine driving a three-bladed fixed-pitch propeller, pushing the maximum speed to 329 mph (529 km/h). Its range was greatly extended, to 1095 miles (1760km) normal or 1990 miles (3200km) maximum.

The III used a 1250 hp (932 kW) Mitsubishi Ha-112 pushing the maximum speed to 358 mph at 21,920 feet (576km/h at 6680 meters.)

The IIIb replaced the 12.7mm with two 20mm Ho-5 cannon.

"Oscar" was just coming into production at the time of Pearl Harbor and first entered combat over Malaya and Burma with 64 Air Regiment. Thanks in part to its "butterfly" combat flaps, it was very maneuverable and a deadly dogfighter, proving an unpleasant surprise to Allied pilots. It soon became the most feared Japanese aircraft in Southeast Asia. However, it was badly undergunned and as fragile as most other Japanese fighters. The initial armament of two rifle-caliber machine guns was rapidly upgraded to two heavy machine guns, but this was still inadequate in comparison with Allied fighters carrying at least four heavy machine guns. The -II had some armor and self-sealing fuel tanks, but still tended to disintegrate if it stumbled into 0.50 caliber fire from an Allied aircraft.

"Oscar" was originally designed to be the successor to the Ki-27 "Nate". The design team, led by Koyama Yasumi and Itogawa Hideo, set out to design the lightest possible airframe around the most powerful available radial engine, the Ha-25. The design closely resembled the Nate, except for the use of retracting landing gear. Army test pilots initially criticized the design failing to match the maneuverability of the Nate, which prompted the designers to lighten the airframe, reduce its cross section, and add the butterfly flaps. The Japanese Army was sufficiently pleased with the redesigned Oscar to attempt to set up two more production facilities. However, there were not enough skilled personnel at Tachikawa Dai-Ichi Rikugun Kokusho (Tachikawa First Army Air Arsenal) and production was halted after a small number of airframes were assembled from components. The production facility at Tachikawa Hikoki K.K. was more successful, and more Oscars were produced than any other Japanese fighter model except the A6M Zero.

It took some time to discover that the wings were not strong enough to withstand the most violent maneuvers, and a number of aircraft were lost when their wings collapsed while pulling out of a dive. Efforts to retrofit the existing aircraft to strengthen their wings were not entirely successful, but the problem was largely solved in the -II.

A small number were supplied to the puppet Thai government. Towards the end of the war, after it was superseded by improved fighter designs, "Oscar" was used extensively in kamikaze service.

In many respects "Oscar" resembled an Army version of the Zero, having similar strengths and weaknesses. However, it was even lighter and more maneuverable. On the other hand, "Oscar" was a full 40 miles per hour (60 kilometers per hour) slower than the Zero, making it slower than most Allied fighters. This speed proved inadequate to protect the Army's heavy bombers in China. As one fighter pilot told Bergerud (2000),

You'd be lucky to get one Immelmann out of a Tony starting from an initial flight attitude, whereas an Oscar, it really could do a double, and I saw it happen too many times. I'm not too sure that a Zero, unless he had proper conditions set up, maximum throttle, and all-out level flight, could do it. But I saw an Oscar to several double Immelmanns, even topped off by a hammerhead stall. That's pretty fancy to watch. It was an enormously maneuverable airplane. The Oscar was designed to be an army fighter for the Manchurian and Chinese theaters. It had great maneuverability but with its armament of two machine guns, it wasn't too far from the Sopwith Camel era in some ways.

Oscar was produced until the end of the war, but production of the -III was turned over to Tachikawa to allow Nakajima to focus on production of the superior Ki-84 "Frank".

Photo Gallery

Captured Ki-43-I in flight



Wikimedia Commons

Ki-43 Oscar captured at Clark Field

U.S. Navy

Ki-43 Oscar configured as kamikaze

Wikimedia Commons

Ki-43 Oscar in Indonesian colors

Wikimedia Commons


Bergerud (2000)

Francillon (1979)
Molesworth (2008)

Peattie et al. (2011)

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