NAMC YS-11

Development and design

Origins

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.

Name

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.

A catchphrase developed around the public reveal of the YS-11 mockup, which was “Let’s meet on the 11th at Sugita in Yokohama.” Here, Yokohama represented the “Y,” the Sugita neighborhood stood for the “S,” and the 11th referred both to the plane and to the date of the public reveal (December 11, 1958). Because of this, it became common to read the “11” in “YS-11” as “eleven” (jūichi in Japanese). For those involved in designing the plane, meanwhile, the designation had originally been pronounced “YS-one-one” (or YS ichi ichi).

Into flight

On 30 August 1962, the first prototype performed its maiden flight from Nagoya Airport; it was soon followed by the second prototype, flying on 28 December 1962. Early flight testing revealed several issues to troubleshoot, including poor steering, excessive vibration and noise.