The Ki 45 was Japan’s first twin-engine fighter and its most successful night fighter. It also served capably in a variety of missions, including ground attack, antishipping, and kamikaze.
The Kawasaki Ki-45 required more time to develop and place in service than almost every other Japanese warplane of World War II. By 1937 the notion of long-range strategic fighters, capable of escorting bomber fleets to targets and back, was becoming prevalent. Germany began successfully experimenting with its Messerschmitt Bf 110, which prompted the Imperial Japanese Army to adopt similar craft. That year it invited several companies into a competition, and Kawasaki, after many trials and prototypes, originated the Ki 45 Toryu (Dragon Slayer). This was a handsome, low-wing design with a pointed nose and a long, tandem cabin housing pilot and gunner. Initial flights revealed that the craft was underpowered, so a succession of better engines ensued until the Nakajima Ha–25 was utilized. Other problems centered around the landing gear, which were weak and hand-cranked in flight. With better motors and powered undercarriage, the Ki 45 showed promise, so in 1941 it entered production. A total of 1,701 were ultimately built, and they received the code name Nick during World War II.
Takeo Doi, chief project engineer, began work on this design in January 1938 but the first production aircraft did not fly combat until the fall of 1942. When it finally entered service, the Ki-45 soon became popular with flight crews who used it primarily for attacking ground targets and ships including U. S. Navy Patrol Torpedo (P. T.) boats. The Toryu was also the only Japanese Army night fighter to see action during the war.
The Japanese did not develop a dedicated single-engined ground support aircraft; the Japanese army relied on light bombers, such as the Ki-30 (‘Ann’), Ki-32 (‘Mary’), Ki-36 (‘Ida’) and Ki-51 (‘Sonia’). These were all obsolescent. However, the Kawasaki Ki-45-KAI Toryu (‘Nick’), although primarily designed as a twin-engined long-range fighter, turned out to be a quite useful attack aircraft. The Ki-45-KAIb version was armed with a 37 mm Type 98 tank gun, which fired the same ammunition as the Type 94 anti-tank gun (not to be confused with the less powerful Type 94 tank gun). The Type 98 was manually loaded. The Ki-45-KAIc instead carried a 37 mm Ho-203, less powerful than the Type 98 but equipped with a 15-round belt feed. The Ho-203 was later scaled up to the Ho-401 57 mm cannon, and this weapon (with 17 rounds) was installed in the attack version of the Ki-102 (‘Randy’) fighter, the successor of the Ki-45. Of this Ki-102b (also known as the Army Type 4 Assault Aircraft) about 200 seem to have been completed. The Ho-401 with its 520 m/s muzzle velocity was a suitable weapon for use against soft targets, but not much use against armour. Rikugun, the army aeronautical research institute, designed the Ki-93 with the Ho-402 in a belly fairing; this was also a 57 mm weapon but much larger and more powerful, firing its projectiles at 700 m/s. However, only one Ki-93 was ever flown. These Japanese aircraft were no longer as unprotected as most Japanese combat aircraft had been at the start of the conflict, but they were not heavily armoured either, the designers’ priorities being performance and handling.
Japanese strategists observed the Americans and the Europeans design and build a number of twin-engine, two-seat, heavy fighters during the mid- and late 1930s. The Japanese Army needed a long-range fighter to cover great distances during any large-scale conflict in the Pacific and army planners felt that a twin-engine design could meet this need. In March 1937, the Japanese Army Staff sent a rather vague specification for such an airplane to a number of manufacturers. Kawasaki, Nakajima, and Mitsubishi responded, but the latter two dropped out of the competition to concentrate on other projects. Between October and December 1937, the army amended the specification with additional information and directed Kawasaki to begin the design work. The specification described a two-seat fighter with a speed of 540 kph (336 mph), an operating altitude of 2-5,000 m (6,560-16,405 ft), and endurance of over 5 hours. The army chose the Bristol Mercury engine, built under license, to power the new aircraft.
In January 1939, Kawasaki rolled out the first prototype but initial flight tests did not impress. The airplane was too slow to meet the army speed requirement, and it suffered mechanical problems with the landing gear and engines. Top speed remained a problem, despite major changes on the second prototype, and the army put the project on hold. In April 1940, Kawasaki substituted 14-cylinder Nakajima engines, rated at 1000 horsepower each, for the original 9-cylinder motors rated at 820 horsepower each. Engineer Doi also revised the engine nacelles and prop spinners. These modifications increased top speed to 520 kph (323 mph) but the revisions continued. Kawasaki narrowed the fuselage, increased the wing span and area, revised the nacelles again, and modified the armament package. The new aircraft did not fly until May-June 1941 but performance at last met army standards and they ordered the Toryu into production.
Kawasaki delivered the first Ki-45 Kai (modified) in August 1942 but Toryus did not reach combat units in China until October. Unlike many Japanese Navy fighter airplanes, the Ki-45 aircraft had crew armour and fire-resistant fuel tanks. These airplanes also carried a heavy gun battery that usually consisted of 20 mm and 37 mm cannons. Toryus operated in the New Guinea area against Allied shipping and attacked Consolidated B-24 Liberator bombers of the 5th Air Force. The Japanese also employed some Ki-45s as night fighters. Field personnel modified these Toryus by substituting the upper fuselage fuel tank for two 12.7 mm machine guns mounted to fire obliquely upwards at a target’s vulnerable belly. This worked so well that the army told Kawasaki to manufacture a night fighter version of the Toryu-the Ki-45 Kai (Mod. C)-with two 20 mm cannon, mounted obliquely, and a 37 mm cannon mounted in the lower fuselage.
In June 1944, 20th Air Force bomber crews flew Boeing B-29 Superfortresses on the first raids against the Japanese home islands since Doolittle’s attack back in May 1942. Bad weather and attacks by Japanese fighter interceptors, including Ki-45 Toryus, hampered these raids. On one mission, Ki-45 pilots downed eight Superfortresses.
On March 9, 1945, the 20th Air Force began flying low altitude attacks at night using incendiary bombs. These missions marked a radical departure from the traditional American high-altitude, daylight bombing strikes. The Japanese fought back with anti-aircraft gunfire and night fighter attacks. As many as six Sentais (groups) of NICK night fighters defended the home islands by war’s end. The Ki-45 Kai Hai (Mod. C) the Japanese Army’s only night fighter, operated alongside Navy night fighters including the Nakajima J1N1-S Gekko (IRVING) and P1Y1-S Byakko (FRANCIS). Examples of the IRVING and FRANCIS are also preserved in NASM’s collection. The NASM Ki-45 Kai Hai (Mod. C) is the last known survivor of 1,700 Ki-45s built by Kawasaki. The company built a total of 477 Kai Hai C night fighters.
The NASM airplane was produced in the second of three batches and the thrust-augmentation exhausts fitted to the engines to improve speed and reduce glare at night identify aircraft in this batch. This NICK was one of about 145 Japanese airplanes returned to the United States for evaluation after the war. The Navy shipped them to Norfolk, Virginia, aboard the escort carrier USS Barnes. On December 8, 1945, the Navy transferred the NICK to the U. S. Army Air Forces at Langley Field, Virginia. Personnel at Langley shipped the Ki-45 to the Air Depot at Middletown, Pennsylvania, for overhaul and flight test. During the next few months, the aircraft was extensively test-flown at Wright Field, Ohio, and Naval Air Station Anacostia in the District of Columbia. During the army’s evaluation, pilots reported that NICK handled very poorly on the ground. They also did not like the cramped cockpit, excessive vibration, and the poor visibility. Takeoff distance, climb speed, flight characteristics, approach and landing, and manoeuvrability were all rated as good to excellent.
The first Ki 45s were deployed in Southeast Asia and, despite exceptional maneuverability for their size, were at a disadvantage fighting single-engine opponents. Given their speed and heavy armament, however, they proved ideal for ground attacks and antishipping strikes. Moreover, the Ki 45 was also an effective bomber interceptor and played havoc with American B-24 formations throughout Burma and Indochina. When the B-24s switched to night attacks, the Ki 45 was converted into a night fighter by mounting heavy cannons on top of the fuselage in slanted fashion. Considerable success was achieved, which gave rise to the Ki 45 KAIc, a dedicated night-fighter version, in 1944. These machines also performed useful work against high-flying B-29s over Japan toward the end of the war. More ominously, on May 27, 1944, it fell upon four Nicks to perform the first army kamikaze attacks against American warships off Biak.
KI-45 Type 1
Modified operative models
Toryu: Two-seat fighter Type 2 of Army (Mark A) initial model of series, one 20mm Ho-3 in ventral position, two Ho-103 12.7mm in the nose and a flexible 7.92mm in the back position
retrofit version based on the KAIa, 20mm belly cannon replaced by a 37mm type 94 tank gun
Mark C version against naval objectives, one 37 mm (1.46 in) Ho-203 automatic cannon in the nose, one 7.92 mm (.312 in) machine gun in the back position.
Mark D, a modified Model B, night fighter version, equipped with one 37 mm (1.46 in) Ho-203 cannon in nose and two fixed 20 mm Ho-5 cannons in a Schräge Musik-style dorsal frontal position, and one 7.92 mm (.312 in) Type 98 machine gun in back position.
Single-seat fighter prototype; later re-designated Ki-96.
Total production: 1,691 or 1701 units depending on source.
Specifications (Ki-45 KAIc)
Length: 11 m (36 ft 1 in)
Wingspan: 15.02 m (49 ft 3 in)
Height: 3.7 m (12 ft 2 in)
Wing area: 32 m2 (340 sq ft)
Airfoil: root: NACA 24015; tip: NACA 23010
Empty weight: 4,000 kg (8,818 lb)
Gross weight: 8,820 kg (19,445 lb)
Powerplant: 2 × Mitsubishi Ha-102 14-cylinder air-cooled radial piston engines, 783 kW (1,050 hp) each
Propellers: 3-bladed constant-speed propellers
Maximum speed: 540 km/h (340 mph, 290 kn)
Range: 2,000 km (1,200 mi, 1,100 nmi)
Service ceiling: 10,000 m (33,000 ft)
Rate of climb: 11.7 m/s (2,300 ft/min)
Wing loading: 171.9 kg/m2 (35.2 lb/sq ft)
Power/mass: 0.26 kW/kg (0.16 hp/lb)
1 × 37 mm (1.457 in) Ho-203 cannon, 1 × 20 mm (0.787 in) Ho-3 cannon, 1 × 7.92 mm (0.312 in) Type 89 machine gun on a flexible mount in the rear cockpit