[NASM/米ワシントンDC]橘花

[スミソニアン航空宇宙博物館別館 NASM. Steven F. Udvar-Hazy Center]橘花

14390 Air and Space Museum Parkway, Chantilly, Virginia 20151 U.S.A.

ワシントン・ダレス空港に隣接するスミソニアン航空宇宙博物館別館 NASM. Steven F. Udvar-Hazy Center には、戦後、占領地日本から研究のために輸送したもの等、日本陸海軍の航空機の大半修復して展示されている。

橘花に海軍が開発した純国産の双発ジェット戦闘攻撃機（日本初の純国産ジェット機）。エンジン開発は主に空技廠(海軍航空技術廠)が担当し、機体を中島飛行機が開発製造。

Nakajima Kikka

The Nakajima Kikka was the only World War II Japanese jet aircraft capable of taking off under its own power. When Germany began to test the jet-propelled, Messerschmitt Me 262 fighter, the Japanese air attaché to Germany witnessed a number of flight trials. Inspired by his enthusiastic reports, the Naval Staff directed Nakajima in September 1944 to develop a twin-jet, single-seat, attack aircraft based on the Me 262. The specifications were somewhat less rigorous than those for the German fighter: range 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); maximum speed of only 696 kph (432 mph); landing speed of 148 kph (92 mph); and a takeoff run of 350 m (1,150 ft) with rocket- assist. These figures fall short of what the Germans achieved with the Messerschmitt design.

Nakajima assigned the project to Kazuo Ohno and Kenichi Matsumura. Their design resembled the Me 262 but was smaller. It was an all-metal aircraft except for the control surfaces, which Ohno and Matsumura covered with fabric. The designers mounted the engines in pods slung beneath each wing, like the German jet. This feature allowed the designers to test different types of jet engines without having to continuously alter the layout of the fuselage structure.

With Japanese industry beset by numerous logistical and technical problems, jet engine design lagged behind airframe development in Japan. Experimentation with turbojet technology had begun in Japan as early as the winter of 1941-42. A 1943 Japanese technical mission to Germany selected the BMW 003 axial-flow turbojet for production. A large cargo of engines, engineering plans, photographs, and tooling traveled to Japan by submarine, which vanished without a trace en route, however, one of the technical mission's engineers traveled aboard another submarine and returned to Japan with his personal notes and several photographs of the BMW engine. The Naval Technical Arsenal at Kugisho developed the Ne-20 turbojet, in part, from that information. The Ne-20 went from initial design to operational ground testing in only six months. During this phase of the design, the naval authorities designated the aircraft Navy Special Attacker Kikka. The phrase 'Special Attack' (Toko in Japanese) denoted an airplane earmarked for missions the Americans called Kamikaze attacks.

The first prototype Kikka was ready by August 1945. Lieutenant Commander Susumu Takaoka made the initial flight on August 7. He made a second attempt four days later but aborted the takeoff and crashed into Tokyo Bay, tearing off the landing gear. Technicians had mounted the two takeoff-assist rockets at the wrong angle.

Development of the Kikka ended four days later with the Japanese surrender. Another prototype was almost ready for flight and American forces discovered about 25 other Kikkas inside a Nakajima factory building in various stages of assembly.

Correspondence with Japanese propulsion specialist Kazuhiko Ishizawa in 2001 indicates that Nakajima constructed the NASM Kikka airframe for load testing, not for flight tests. This explains why the engine nacelles on the NASM Kikka airframe are too small to enclose the Ne-20 engines. There is no further information on the subsequent fate of the airframe used for flight tests that crashed on its second flight.