Mitsubishi Ki-67

The Mitsubishi Ki-67 Hiryū (飛龍, "Flying Dragon"; Allied reporting name "Peggy") was a twin-engine heavy bomber produced by Mitsubishi and used by the Imperial Japanese Army Air Force in World War II. Its Army designation was "Type 4 Heavy Bomber" (四式重爆撃機).

Design
The Ki-67 was the result of a 1941 Japanese army specification for a successor to the Nakajima Ki-49. This new aircraft was specified to be a high-speed twin-engined heavy bomber suitable for possible conflicts with the Soviet Union over the Manchuria-Siberia border, and unlike many Japanese warplanes, was required to have good defensive armament and the ability to survive heavy battle damage. It was also required to be highly maneuverable allowing it to carry out dive-bombing attacks and escape at low level.

The Ki-67 was designed by a team led by Kyūnojō Ozawa, chief engineer at Mitsubishi, and was a mid-winged monoplane of all-metal construction, with a retractable tailwheel undercarriage. It was fitted with self-sealing fuel tanks and armor, features common in US fighters and bombers but frequently lacking in Japanese aircraft. With these features and its two 1,417 kW (1,900 hp) 18-cylinder air-cooled radial engines, the Ki-67 was perhaps one of the most sturdy and damage-resistant Japanese aircraft of World War II.

The Ki-67's bomb load of 1,070 kg (2,360 lb) (carried in its internal bomb bay) would classify it as a medium bomber for the US (the B-25 Mitchell could carry up to 2,722 kg (6,000 lb), the B-26 Marauder up to 1,814 kg (4,000 lb), and the A-20 Havoc up to 907 kg (2,000 lb), for example). Its performance was remarkable compared to US medium bombers; the Ki-67 had a level-flight top speed of 537 km/h/334 mph (against 443 km/h/275 mph for the B-25, 462 km/h/287 mph for the B-26, and 538 km/h/338 mph for the A-20), good maneuverability in high-speed dives (up to nearly 644 km/h/400 mph), excellent sustained rate of climb, and outstanding ability to turn (excellent turn rate, small turn radius, and ability to turn at low speeds). The maneuverability of the Ki-67 was so good that the Japanese used the design as the basis for the Ki-109 twin-engine fighter, originally designed as a night fighter, and later for use as a daylight heavy fighter. In the last stages of World War II, the Japanese Navy also used the design as the basis for the Q2M1 "Taiyo" radar-equipped anti-submarine aircraft.

Another interesting feature of the Ki-67 was that the gun in the dorsal gunner's turret position was a 20 mm Type 99 cannon. (In addition to twin 12.7 mm/0.5 in machine guns in the tail, one 12.7 mm/0.5 in gun in the nose, and one 12.7 mm/0.5 in gun at each waist-gun position.)

Operations
The Ki-67 was used for level bombing and (as the Yasakuni Type) torpedo bombing (it could carry one torpedo attached under the fuselage). The Ki-67 was initially used by the Japanese Army and Navy Air Services against the US 3rd Fleet during its strikes against Formosa and the Ryukyu Islands. It was later used at Okinawa, in Mainland China, French Indochina, Karafuto and against B-29 airfields in Saipan and Tinian. One special ground-strike version used in the Giretsu missions was a Ki-67 I with three remote-control 20 mm cannons angled at 30° for firing toward the ground, a 20 mm cannon in the tail, 13.2 mm (.51 in) machine guns in the lateral and upper positions, and more fuel capacity. Even with more fuel, the Giretsu missions were one-way only because of the long range. In the last stages of World War II, special attack versions of the Ki-67 (the I KAI and Sakura-dan models) were used in kamikaze missions. (References include information from Lt. Sgt. Seiji Moriyama, a crew member in Fugaku Special Attack Unit, who witnessed Ki-67's being converted into To-Gō suicide planes with two 800 kg/1,760 lb bombs during Okinawa operations.)

By the end of World War II, 767 Ki-67s had been produced. Other sources relate that 698 Ki-67's were manufactured, excluded the KAI and Sakura-dan conversions.

Variants

 * Ki-67-I: Prototypes. Diverse models with various types of weapons. 19 produced.
 * Ki-67-Ia "Hiryu" Army Heavy Bomber Type 4, Model 1: Main production model. The majority (420+) were modified in the factory as land-based torpedo bombers (after work-number 160). Produced by Mitsubishi: 587; by Kawasaki: 91; by bu 1° Army Arsenal of Tachikawa: 1.
 * Ki-67-Ib: Late production model. Reinforced the tail gun turret (2 × 20 mm).
 * Ki-67-I KAI: Experimental model equipped with Mitsubishi Ha-104 Ru engines. 3 produced.
 * Ki-67-I AEW variant: Equipment the early warning radar "Taki 1 Model II". 1 produced.
 * Ki-67 "To-Gō": Army special attack aircraft type 4: Improved version of the Ki-67 I for kamikaze, unarmed, without turrets, and with two 800 kg (1,760 lb) bombs in belly compartment.
 * Ki-67 "guided missile mother ship": Experimental type for carrying guided missiles.(Kawasaki Ki-147 I-Go Type 1-Ko,Mitsubishi Ki-148 I-Go Type 1-Otsu, I-Go Type 1-Hei, "Ke-Go" IR, "Ko-Go","Sa-Go") 1 produced.
 * Ki-67 long-range bomber variant: Equipped with widened wings and without turrets. Only a project.
 * Ki-67 ground attack variant: Version armed with three remote-control ground-firing 5 × 30° 20 mm cannons, 20 mm defensive cannon in the tail position, three 13.2 mm (.51 in) machine guns in lateral and upper positions, and more fuel capacity for long range. Specifically designed for land strikes against B-29 bases in the Marianas. Only a project.
 * Ki-67-II: Prototypes. Modified version of the Ki-67-I, with two Mitsubishi Ha-214 engines of 1,603 kW (2,150 hp) each. 2 produced.
 * Ki-67 glider tug: A standard Ki67-I was used to tow the "Manazuru" (Crane) transport glider in tests.
 * "Yasukuni": Naval torpedo bomber version of the Ki-67-I. Created from Ki-67-Is transferred from the IJAAF.
 * Ki-69: Heavily-armed escort fighter model. Only a project.
 * Ki-97: Transport model. Only a project.
 * Ki-109: Night fighter prototypes. Ki-67-I modified for night fighting for operating in pairs, the Ki-109a with a radar/reflector (similar to the Douglas Havoc II "Turbinlite") for radar transmission and detection and the Ki-109b, armed with twin 37 mm Ho-203 cannon in an upward-firing Schrage Musik-style fixed dorsal mount (as the single Ho-203 autocannon in the Mitsubishi Ki-46-III KAI was) to destroy the objective. Only a project.
 * Ki-109: Day Fighter prototypes. Ki-67-I modified for daylight fighting. One fixed 75 mm Type 88 Heavy Cannon in the nose and one mobile 12.7 mm (0.5 in) Ho-103 Type 1 machine gun in the tail. Equipped with Mitsubishi Ha-104 engines of 1,417 kW (1,900 hp) each or turbochargers Ha-104 Ru with 1,417 kW (1,900 hp) each. 2 produced.
 * Ki-109 Army Heavy Fighter Interceptor: First non-prototype model of series. Lacking gun positions in upper and side positions and without bomb-bay compartments. Fixed 75 mm Type 88 Heavy Cannon in the nose retained from Day Fighter prototype. Had a revised version of tail gun. 22 constructed by Mitsubishi.
 * Ki-112: Wooden bomber model. Only a project.
 * Ki-167 "Sakura-dan": Special attack version equipped with one shaped charge thermite bomb of 2,900 kg (6,400 lb) in the fuselage behind the crew cabin. The shape of the bomb conducted the blast forward, projecting a jet capable of reaching nearly a mile with a maximum blast radius of 300 m (980 ft). The bomb was designed to breach emplacements as well as to destroy massed formations of armor. 9 produced.
 * Q2M1 "Taiyo": A Navy variant based on the Ki-67-I, specifically designed for antisubmarine warfare. Equipped with radar units (Type3 Model 1 MAD (KMX), Type 3 Ku-6 Model 4 Radar, and ESM Antenna equipment). Had two Mitsubishi Kasei 25 Otsu engines of 1,380 kW (1,850 hp) each with six-blade propellers. Carried torpedoes or depth charges. Only a project.

Wartime

 * Japanese Imperial Army
 * Hamamatsu Instructing Flying Division
 * 7th Hikō Sentai
 * 14th Hikō Sentai
 * 60th Hikō Sentai
 * 61st Hikō Sentai
 * 62nd Hikō Sentai
 * 74th Hikō Sentai
 * 110th Hikō Sentai
 * 170th Bombardment Group (ex-60th Hikō Sentai and 110th Hikō Sentai)
 * Japanese Imperial Navy
 * 11th Air Flotilla
 * 11th Air Flotilla

Postwar

 * Indonesian Air Force
 * Indonesian Air Force