History of the Mitsubishi Ki-109
The Mitsubishi Ki-109 is a special derivative of the Mitsubishi Ki-67 heavy bomber described elsewhere on this page. The Ki-109 is specifically designed to counter the growing threat posed by the American Boeing B-29 Superfortress flying high above the Japanese mainland.
As such, the Ki-67 was selected for its reasonable performance specifications and was considered for the new bomber role.
Initially, the Ki-109 plan was to use two Ki-109 aircraft, one with searchlights and a powerful radar, and the other with a powerful large-caliber gun. This "hunter-killer" pairing is supposed to work together to detect incoming enemy threats and eliminate them in complete darkness.
However, the system proved to be quite complex, so only one Ki-109 design emerged, now serving as a day interceptor, although it was still fitted with a large-caliber gun.
The Ki-109 retains many of the visual qualities of the Ki-67 heavy bomber. Major changes include the lack of powerful defensive weapons and the use of more powerful engines than its predecessor (2 Mitsubishi Ha-104 series piston engines with 1,900 hp).
The Ki-109 was defended only by a single heavy 12.7mm machine gun at the rear. In addition, her weapons are aggressive, including a 75mm anti-aircraft gun in the nose.
This system is manually loaded but can be fired from a Ki-109 aircraft, which is still well beyond the range of the B-29's defensive machine gun weapons.
The new Mitsubishi Ki-109 entered limited production, with only about 24 prototypes in the end (2 were Japanese prototypes). Although the Ki-67's maneuverability was preserved, the system proved to lack the true high-altitude performance required of the type.
However, this is largely moot at this point in the war, as U.S. bombers are now conducting low-altitude night operations to improve accuracy. The Ki-109 was at best a temporary design that never saw its true combat potential.
However, from a fully defensive standpoint, this was the case, as the Japanese Empire was in conflict at the time.
Specification
Basic
Production
Roles
- Fighter
- Intercept
Dimensions
17.95m
22.5m
19.03 ft (5.8 m)
Weight
7,424 kg
10,800 kg
Performance
Performance
342 mph (550 km/h; 297 knots)
31,070 ft (9,470 m; 5.88 mi)
1,367 miles (2,200 km; 1,188 nautical miles)
450 m/min
Armor
Default:
1 x 75mm Type 88 cannon in the nose position
1 x 12.7mm HO-103 Type 1 machine gun in rear position.
Changes
Ki-67 - The bomber variant on which the Ki-109 is based.
Ki-109 - Heavy fighter-bomber interceptor; equipped with Mitsubishi Ha-104 piston engines 1,900 hp each; 1 x 75mm machine gun in forward position and 1 x 12.7mm machine gun in defensive stern position; produced as armed version only 22 examples (as shown in the Ki-109b model proposal below).
Ki-109a - Proposed "Jager" version with radar and searchlights, for use with "Killer" model.
Ki-109b - "Killer" version with heavy weapons used with the "Fighter" model.


