Earlier this year, our collections staff at the Udvar-Hazy Center, in Chantilly, Virginia, moved the Nakajima Kikka from beneath the wing of the Sikorsky JRS flying boat in the Mary Baker Engen Restoration Hangar and out onto the floor beneath the Boeing B-29 Enola Gay. Moving the Kikka provides an opportunity to bring visitors closer to the last known example of a World War II Japanese jet aircraft and the only Japanese jet to takeoff under its own power—it also opened up space in the Hangar so that our team could install netting to deter birds.
The Kikka took cues from the German Messerschmitt Me 262 fighter. When Germany began to test the jet-propelled Messerschmitt Me 262 fighter in 1942, the Japanese air attaché to Germany witnessed a number of its flight trials. The attaché’s enthusiastic reports eventually led the naval staff in Japan to direct the Nakajima firm in September 1944 to develop a twin-jet, single-seat, aircraft similar in layout to the Me 262.
Nakajima leadership assigned the project to engineers Kazuo Ohno and Kenichi Matsumura. As the war continued to deteriorate for Japanese forces, Japanese naval pilots launched the first suicide missions using aircraft in October 1944. Several aircraft manufacturers turned to designing aircraft specifically for use during suicide missions, including the Nakajima Kikka. Ohno and Matsumura led the design as it developed an all-metal aircraft except for the fabric-covered control surfaces. The designers planned to hinge the outer wing panels to fold up so that ground personnel could more easily hide the aircraft in caves. They mounted the jet engines in pods slung beneath each wing to make it easier to install and test different engines. Three different engines were tried before the designers settled on the Ne-20, an engine that drew heavily from the German BMW 003.
Experimentation with turbojet engine technology had begun in Japan as early as the winter of 1941-42 and in 1943, a Japanese technical mission to Germany selected the BMW 003 axial-flow turbojet for development in Japan. A large cargo of engines, engineering plans, photographs, and tooling sailed for Japan by submarine but vanished at sea. However, one of the technical mission engineers had embarked aboard another submarine and arrived in Japan with his personal notes and several photographs of the BMW engine. The Naval Technical Arsenal at Kugisho developed the Ne-20 turbojet based on this information.
Due to the lack of high-strength alloy metals, the turbine blades inside the jet engine could not last much beyond a few hours but this was enough time for operational testing and 20 to 30 minute flights for a one-way suicide missions.
The first prototype Kikka was ready to fly by August 1945. Lieutenant Commander Susumu Takaoka made the initial flight on August 7 and attempted to fly again four days later but he aborted the takeoff and crashed into Tokyo Bay, tearing off the landing gear. Various sources offer different causes for the crash. One writes that technicians had mounted the two takeoff-assist rockets at the wrong angle on the fuselage while another ascribes blame on the pilot who mistook the burnout of the takeoff rockets for turbojet engine trouble, throttled back, and executed a safe but unnecessary crash landing. Development of the Kikka ended four days later when the Japanese surrendered. Another prototype was almost ready for flight and American forces discovered about 23 Kikka aircraft under construction at the Nakajima main factory building in Koizumi (present day Oizumi in Gunma Prefecture), and at a site on Kyushu island.
Despite considerable research in the U.S. and Japan, we know little about the origins of the Museum’s Kikka. We can only say that American forces shipped several Kikka’s and probably major components to the U.S. after the war, but we do not know which factory they originated from. U.S. Navy records show the Museum’s Kikka at NAS Patuxent River, MD on February 18, 1949. The aircraft was shipped from Norfolk on September 2, 1960 to the Paul Garber Facility in Suitland, MD. Museum staff accessioned the Kikka into the collection on March 13, 1961. Correspondence in 2001 with Japanese propulsion specialist Kazuhiko Ishizawa theorized that Nakajima constructed the Museum’s Kikka airframe for load testing, not for flight tests. This may explain why the engine nacelles on the Museum’s Kikka airframe are too small to enclose the Ne-20 engines, but it does not explain why the airframe is relatively undamaged. Load testing often results in severe damage or complete destruction of an airframe. There is no further information on the subsequent fate of the Kikka that crashed on its second test flight. Treatment specialist staff at the Udvar-Hazy Center confirmed that the Museum’s Kikka is fitted with manual folding wings.
Kikka and Messerschmitt Me 262 Compared
Based on the performance requirements for a one-way suicide mission, and the size and output of the Ne-20 engine, the performance goals for the Kikka differed considerably from the goals set for the German fighter. The Kikka’s estimated range was 205 km (127 mi) with a bomb load of 500 kg (1,102 lb) or 278 km (173 mi) with a load of 250 kg (551 lb) at a maximum speed of 696 km/h (432 mph). A takeoff run of 350 m (1,150 ft) was predicted with rockets mounted on the fuselage to shorten the run, and for training flights, the Kikka was expected to land at 148 km/ (92 mph). The Me 262 A-1a production fighter could fly 845 km (525 miles) with a typical military payload of 4 x MK 108 cannon (30 mm) and 2 x 300 ltr (79 gal) drop tanks at 870 km/h (540 mph) maximum speed. The pilot of the German fighter could land at 175 km/h (109 mph) and required 1,005 m (3,297 ft) to takeoff without rocket-assist.
Although the Kikka resembles the Me 262 in layout and shape, the German jet is actually considerably larger. Here is a comparison of both aircraft:
Experimental Prototype Kikka:
Wingspan: 10 m (32 ft 10 in)
Production Me 262 A-1a Fighter:
12.65 m (41 ft 6 in)
J. Richard Smith and Eddie J. Creek, Jet Planes of the Third Reich, (Boylston, MA: Monogram Aviation Publications, 1982).
René J. Francillon, Japanese Aircraft of the Pacific War, (London: Putnam, 1979).
Robert C. Mikesh, Kikka, Monogram Close-Up 19, (Monogram, 1979).
Tanegashima, Tokyasu. “How the First Jet Engine in Japan was Developed,” Gas Turbines International, November-December 1967, 1200. Nakajima Kikka Curatorial File, Aeronautics Department, The National Air and Space Museum, Washington, DC