Mitsubishi Ki-67 Hiryu Peggy
The Mitsubishi Ki-67 Hiryu ("Flying Dragon"), reported by the Allies as "Peggy", was a twin-engine bomber built for the Imperial Japanese Army Air Service and also flown by the Navy as a torpedo bomber. Designed to a specification handed to Mitsubishi in February 1941 and first flown on 27 December 1942, it matched medium-bomber performance with the armour and self-sealing fuel tanks that earlier Japanese bombers lacked. Production reached 698 aircraft by the end of the war, but deliveries only began in the summer of 1944, so its service over Formosa, Saipan and Okinawa came too late to affect the outcome.
Why It Mattered
The Mitsubishi Ki-67 was the Imperial Japanese Army's Type 4 Heavy Bomber, designed against a possible Japanese-Soviet conflict from a specification first drafted late in 1940 and given to Mitsubishi on 17 February 1941. History of War rates it the finest bomber flown by the Imperial Japanese Army in the Second World War, yet operational deliveries did not begin until summer 1944, too late for the type to change the war's course. In capability it sat nearer the American twin-engined medium bombers than the heavy bombers its designation suggested. What set it apart from earlier Japanese bombers was protection: its fuel and oil tanks were self-sealing and armour was provided from the start. The Japanese named it Hiryu, "Flying Dragon"; the Allies reported it as "Peggy".
Design Notes
The Army specification called for a top speed of 342 mph, a normal crew of six to eight, and at least one machine gun in the nose, port and starboard positions, with further guns in dorsal and tail turrets. Fumihiko Kawano held overall control of the project for Mitsubishi and appointed Hisanojo Ozawa as chief project engineer. Ozawa chose the 1,900 hp Mitsubishi Ha-104 fan-cooled radial and a slim, mid-winged monoplane whose wing and tail were similar to those of the Mitsubishi G4M1. He designed the airframe to be easy to build, using sub-assemblies so that production could be spread out, and, departing from standard Japanese practise, gave it self-sealing fuel and oil tanks and armour from the start. As flown, the bomber carried 12.7 mm Type 1 machine guns in the nose and tail and a 20 mm Ho-5 cannon in the dorsal turret, a maximum bomb load of 1,764 lb, and torpedo racks that were added to every aircraft starting with No. 161.
Operational History
The first prototype was completed in November 1942 and made its maiden flight on 27 December 1942. After sixteen service-test aircraft, the design was frozen on 2 December 1943, when it was accepted as the Type 4 Heavy Bomber Model 1A. Production was shared out: Mitsubishi produced 606 aircraft, Kawasaki 91 at Gifu, Nippon Kokusai completed 29 Mitsubishi-built aircraft, and the 1st Army Air Arsenal at Tachikawa built a single aircraft — 698 in all by the end of the war. Its first combat sorties came in October 1944, off Formosa, where the Army's 7th Sentai, the 98th Sentai and the Navy's 762nd Kokutai flew it against shipping with torpedoes; the Navy called its torpedo aircraft "Yasakuni". From the autumn of 1944, Army Ki-67s staged through Iwo Jima to raid the B-29 airfields on Saipan, timing their attacks for just as the B-29s were preparing to take off, heavily laden with fuel and bombs; the costly raids stopped after American forces came ashore on Iwo Jima on 19 February 1945. Until the war ended it went on flying both jobs: dropping torpedoes on Allied shipping near Okinawa and Formosa, and bombing targets in China as a heavy bomber. Its airframe also spawned specialised versions: the Ki-67-I Kai special-attack conversion, its turrets removed and faired over and its crew cut to three, carrying two 1,764 lb bombs or a special 6,393 lb explosive charge; the Ki-109 heavy fighter, of which Mitsubishi built 22 with a fixed 75 mm cannon in the nose; and the Ki-167 "Sakura-dan", nine of which were built around a single 2,900 kg shaped charge.
Afterlife
The Ki-67 was retired in August 1945, at the war's end. The Ki-67-II, a stronger version to have been powered by two 2,400 hp Mitsubishi Ha-214 radial engines, was left half-completed, with production due to have started in the summer of 1946; the Navy's Q2M anti-submarine development of the design remained a project only. Pacific Wrecks' list of known examples for the type holds just two aircraft, both in the Philippines: manufacture number 177, captured at Clark Field, and one abandoned at Lingayen Airfield.