POWER PLANT: One Kayaba Model 1 ramjet engine rated at 750 kp thrust at 457 mph and four solid fuel rocket boosters for take-off, rated at 7.200 kp thrust
PERFORMANCE: 559 mph (estimated)
COMMENT: The Kayaba “Katsuodori” (“Booby Gannet”) was the result of the endeavor to design a single-seat, ramjet-powered interceptor-minded platform which utilized a short, tailless fuselage configuration with swept-back wing main planes. The cockpit would be held well-forward and offered exceptional vision for the pilot. The mid-mounted main planes were affixed ahead of midship with each tip capped by small vertical stabilizers. The ramjet propulsion system was buried within the tubular fuselage and a rocket-assist scheme (consisting of four externally-held rocket pods) was to be used. The rocket pods were installed under the wing roots and jettisoned once their usefulness had run out. Having achieved the required speeds, the aircraft would then continue on under ramjet power with a flying window of about 30 minutes being estimated. To aspirate the ramjet, the nose section featured an air intake. No conventional undercarriage was provided. Instead the aircraft would glide back home powerless and land on a belly-mounted skid. The ramjet under consideration for the project became the Kayaba Model 1 which promised 750 kp thrust output.
Since the aircraft never achieved prototype form, performance specifications were estimated and this included a maximum speed of 560 miles per hour with a rate-of-climb around 11,000 feet-per-minute. The latter would prove a good quality to have in interception sorties. The service ceiling was listed at 49,215 feet
As an interceptor attempting to tackle very large, slow-moving (but well-defended) targets, it was seen to arm the fighter appropriately through 2 x 30mm Ho-301 series cannons – this was a suitable arrangement to counter even the high-flying and technologically advanced Boeing B-29 “Superfortress” which had made its presence known since mid-1944. The cannons would have been embedded in the sides of the nose.
Design work on the “Katsuodori” progressed into 1943 and plans were underway to begin construction of a working prototype for the following year. However, Japan’s fortunes in the war had worsened into 1944 and the attention of authorities turned to more viable military weapons such as the Rikugun (Mitsubishi) Ki-202 “Sharp Sword”, based on a rocket-powered interceptor developed by Mitsubishi as Ki-200 “Shusui” for the IJAAF and J8M-1 for the IJNAF on the basis of the German Messerschmitt Me 163 “Komet” (Ref.: 24).
POWER PLANT: One Ishikawajima Ne-130 turbojet engine, rated at 900 kp thrust
PERFORMANCE: No data available
COMMENT: The concept of Kyushu J7W1 unique canard configuration was due to designers of the Technical staff of the Japanese Navy. From the onset of that project it was envisaged to replace the rear-mounted Mitsubishi Ha-43 air-cooled radial engine, which drove a six-blade pusher propeller, with the new turbojet engines under development at that time.
Following some initial work on that concept, the staff of Dai-Ichi Kaigun Koku Gijitsusho (First Naval Air Technical Arsenal) designed a glider to test the aircraft’s handling qualities at low speeds. Three prototypes of the MXY6 were built for the Navy by Chigasaki Seizo K.K. and these all-wood gliders with moderately swept wings supporting tall tail surfaces inboard the ailerons began flight trials in autumn of 1943.
Although the “Shinden” was expected to be a highly maneuverable interceptor, only two prototypes were finished before the end of war. And of course the turbojet engine powered Kyushu J7W2 was never realized, it didn’t even reach the drawing board (Ref.: 24).
POWER PLANT: Two Mitsubishi Ha 42 twin-engines, rated at 2,400 hp each
PERFORMANCE: 346 mph
COMMENT: The Mitsubishi G7M was basically a derivative of the most famous Mitsubishi G4M Navy attack bomber. It was originally designed as a long range, strategic bomber able to carry a greater payload over a longer distance. To meet these requirements a four-engine design was favored.
When detailed information about the German Heinkel He 177 became available – a four-engine heavy bomber with dive-bombing capability, powered by two H-engines twinned together in one nacelle on each side thus reducing drag – the G7M design was changed in that manner. Germany promised to deliver the needed machinery to produce the H-engines under license. Other features of the Heinkel design were incorporated, too, such as the glazed nose, four-blade propellers, and a similar tail plane. In contrast the Mitsubishi design used a tricycle landing gear system. The ongoing war situation made it impossible to import the German H-engines as well as the tools for production and the design was changed again to a four-engine bomber but the end of the hostilities stopped all further work (Ref.: 24).
POWER PLANT: One Ishikawajima Ne-230 axial-flow turbojet engine, rated at 885 kp thrust
PERFORMANCE: Data not available
COMMENT: The availability of more sophisticated turbojet engines in the closing stage of the Pacific War brought the Japanese aircraft industry to plans to design completely new turbojet fighters, such as Nakajima Kikka, Nakajima Ki-201 Karyu (Fire Dragon), and Rikugun Ki-202, or to provide newest piston engine designs with turbojets. Examples are the conversion of the Kyushu J7W1 Sinden (Magnificent Lightning) into the Kyushu J7W2 with one Ishikawajima Ne-130 turbojet engine, the Yokosuka R2Y1 Keiun (Beautiful Cloud) with two Ishikawajima Ne-330 turbo jet engines, and Mitsubishi J4M-1 Senden (Flashing Lightning). This twin-boom fighter project, powered by a Mitsubishi MK9D radial engine, driving a six-blade pusher propeller was redesigned to a much smaller aircraft, also in twin-boom configuration, but powered by one Ishikawajima Ne-230 axial-flow turbojet engine, that was expected to give 885 kp thrust. But the end of the hostilities brought all work on this Mitsubishi J4M-2 Senden-Kai project to a halt.
TYPE: High performance interceptor fighter. Project
ACCOMMODATION: Pilot only
POWER PLANT: One Mitsubishi Ha-43 radial engine, rated at 1,650 hp at 26,247 ft, driving 6-bladed metal constant speed pusher propeller
PERFORMANCE: 470 mph at 26,247 ft
COMMENT: To provide the Imperial Japanese Navy with a land-based high-performance interceptor aircraft, Mitsubishi designed the J4M Senden (“Flashing Lighting”) or Navy Experimental 17-Shi Otsu B Type Interceptor Fighter Senden. It was to have been a single-seat, twin-boom, low-wing monoplane with a central nacelle housing an unstepped cockpit and a 2,130-hp Mitsubishi MK9D (Ha-43) radial engine behind the pilot driving a six-bladed pusher propeller rotating between the booms. The booms were to extend aft from the leading edge of the wing and were mounted below the central nacelle. The aircraft was to have had tricycle landing gear and an armament of one 30-mm and two 20-mm cannon. Design of the initial J4M1 version ended when the Navy put its support behind the competing Kyushu J7W fighter. So the J4M project did not proceed beyond the design stage. The Allies nonetheless assigned the J4M the reporting name “Luke” during World War II.(Ref.: 23)