NAMC YS-11

The NAMC YS-11 is a turboprop airliner designed and built by the Nihon Aircraft Manufacturing Corporation (NAMC), a Japanese consortium. It was the only post-war airliner to be wholly designed and manufactured in Japan until the development of the (ultimately cancelled) Mitsubishi SpaceJet during the 2010s, roughly 50 years later.

Development of the YS-11 can be largely attributed to Japan's Ministry of International Trade and Industry (MITI), which had encouraged Japanese aircraft companies to collaborate on the development of a short-haul airliner as early as 1954. In 1959, NAMC was formed to design and produce an aircraft to satisfy MITI's requirements, dubbed the YS-11. On 30 August 1962, the first prototype performed its maiden flight. Deliveries commenced on 30 March 1965, and commercial operations began the following month. The majority of orders for the type were issued from various Japanese airlines. While sales to such customers were swift in the YS-11's initial years of availability, this limited market soon became saturated, leading to a slump in demand.

Production of the type came to an end in 1974 as a result of efforts to increase sales to international clients, including the creation of the better YS-11A variation. In the end, the YS-11 had shown that Japan was capable of building an airliner, but NAMC had racked up a huge debt, and the type is generally regarded as a commercial failure. Large numbers of the type continued to be in service until 2006, at which point tighter Japanese aircraft regulations imposed by the Ministry of Land, Infrastructure, Transport and Tourism necessitated either the withdrawal or refitting of all YS-11s. By 2018, only a single example reportedly remained in commercial service.

During the mid-to-late 1950s, the Japanese Ministry of International Trade and Industry (MITI) identified a requirement for a short-haul airliner to replace Douglas DC-3s flying on Japan's domestic routes, and encouraged companies in Japan's aircraft industry to collaborate to develop and produce a domestic airliner to meet this need. Towards this purpose, in May 1957, the Commercial Transport Design Research Association was established and the availability of government subsidies guaranteed. From the government's viewpoint, the development of such an airliner was viewed as a key initiative towards the post-war revival of the nation's aircraft companies, which came in addition to the serious ambition to become a major international competitor in the global airliner business. Furthermore, while this requirement had been conceived primarily in a commercial context, there was an early recognition of the value for multiple branches of the Japanese Defense Agency (JDA) to be readily able to adopt the type as well; as a philosophy, this not only extended to the prospective airliner itself, but the various technologies involved in its development and manufacture.

In response to this encouragement, during 1957, a joint venture between Mitsubishi Heavy Industries, Kawasaki Heavy Industries, Fuji Heavy Industries, Shin Meiwa, Showa Aircraft Industry Company and Japan Aircraft Industry Company was established for the purpose of developing and manufacturing the envisioned airliner. Two years later, this partnership was formalised as the Nihon Aeroplane Manufacturing Company (NAMC). The ownership of NAMC was initially divided between the Japanese government, which held 54% of the shares, while the constituent aircraft manufacturers held an 18% stake and several components/materials suppliers owned 11%; the remaining shares were small stakes belonging to various banks, insurance companies, and stock firms who chose to invest in the programme. However, NAMC was essentially a "paper company", being reliant upon both personnel and infrastructure provided by its constituent manufacturers.

NAMC designed a low-winged twin-turboprop-engined monoplane, capable of seating up to 60 passengers, dubbed the YS-11. Amongst the design team was Jiro Horikoshi, who had previously been the designer of the famed wartime Mitsubishi A6M Zero fighter. Another prominent engineer on the project was Teruo Tojo, the second son of Prime Minister Hideki Tojo, who later became chairman of Mitsubishi Motors. The twin-engined YS-11 was projected as delivering similar operational performance to the four-engined British-built Vickers Viscount, while possessing 50% greater capacity than the similarly configured Dutch-built Fokker F27 Friendship. MITI supervised the pricing of the aircraft in order to ensure that it was competitive with the American-built Martin 4-0-4.

Although the tentative aircraft was mainly designed and manufactured in Japan, the engine selected to power the airliner was the 2,275 kW (3,050 ehp) Rolls-Royce Dart RDa.10/1 powerplant, which was both developed and produced by British-based company Rolls-Royce. Furthermore, according to author Stephen C Mercado, due to the lack of available domestic technology at the time, several of the key aircraft systems, such as cabin pressurization, were copied from foreign sources; such information was gleaned from a combination of Japanese airlines, trading companies and diplomats. Throughout the YS-11's production lifetime, its electronic equipment, avionics, mechanical and fuselage components were supplied by a combination of Japanese companies and foreign suppliers.

The “YS” of the YS-11 comes from a combination of the first letter sounds of the two Japanese words yusō (transport) and sekkei (design), which refer to the Association for Research on Transport Aircraft Design (Yusōki sekkei kenkyū kyōkai). Meanwhile, the first “1” of the “11” refers to the various engine candidates considered for the YS-11; the Rolls-Royce Dart RDa.10/1, which was the engine selected, had been designated “number 1.” The second “1” refers to the aircraft specification plan selected for the YS-11, which had been one among many plans that differed by wing placement and size. There had also been a “plan 0” at one point.