Soon after the Z-5 development project was completed, China began efforts to develop an indigenous helicopter independently. Based on the military Services' conversion requirement and to make up Z-5's deficiency, e.g. insufficient power, poor performance at high temperature and high altitude and low payload, the Harbin Aircraft Factory began to develop the first indigenous helicopter Z-6 helicopter in 1966. The development work was transfered to a newly founded Helicopter Design and Research Institute in 1968. Compared to the piston-powered Z-5/Mi-4, the Z-6 helicopter had many advanced features, including a 1,618 kW Wozhou-5 turboshaft engine, which provided for a larger payload, and less vibration and noise. The blades and fuselage were re-designed to achieve better performance in highland regions. The Z-6 also borrowed many mature features and technologies from the Z-5's design, including the rear hatch, tail boom and fin.
The Z-6 was primarily intended to carry airborne troops in the frontline, with a fuselage to accommodate 12 soldiers. It is a general purpose helicopter but is mainly used for airborne landing. It can also be converted to adapt different mission requirements. The Z-6 helicopter is powered by a WZ5 turboshaft engine which is installed at the top of the fuselage. It has a maximum take-off weight of 7,600 kg, a payload of 1,200 kg, a maximum speed of 192 km/h and a ferry range of 650 km.
The first prototype (No.6001) of the Z-6 was completed in 1967 for static tests. In 1968, the Z-6 project was officially authorized by the PLA and Chinese Government. On December 15, 1969 pilot Wang Peiming flew the Z-6 for its first time. Prior to the first flight he simulated the sudden shutdown of the engine and the autorotation for three times to ensure the successful first flight. The simulation not only tempered the pilot but also further verified the theoretical analysis. On 25 December 1969 the second Z-6 prototype No.6002 made its first flight.
In 1970 many provinces made great efforts to develop their own aviation industry. The development and the production of the Z-6 were thus transfered to Jiangsu province and Jiangxi province. A situation was formed in which three provinces with a common syllable "jiang" (i.e. Heilongjiang, Jiangsu and Jiangxi) were involved in the Z-6 program. Jiangsu province organized 7 cities, 6 prefectures and more than 470 factories to coordinately work on the Z-6 program. The Hongzhuang Machinery Factory in Changzhou was responsible for final assembly and a total of 11 Z-6s were successively constructed.
From 1970, the Z-6 program was relocated to the newly founded Changhe Aircraft Factory (now Changhe/Jingdezhen Aircraft Industry Corporation ) in Jiangdezhen, Jiangxi, which later became the second largest helicopter manufacturer in China.
On August 7, 1972 a Z-6 crashed near Gongzhuling, Jilin province and all 6 people onboard including pilot Fu Guifa died in the accident. The accident was caused by the jam of a shaft inside the engine gear box. The disastrous and bloody lessons were learnt from the accident and 11 design improvements to the helicopter and the engine were made afterwards. Several technical problems, e.g. severe vibration, overtemperature of the oil, over high idle engine power, jam between the rotor and the oil separator and insufficient tail rotor thrust were tackled by the technical people one after another in the development process. In 1977 the State Council and the Military Commission of CCCPC formally issued a design certificate to the Z-6 helicopter.
The Z-6 helicopter was type classified in 1977, by which time 15 helicopters had already built. Despite being a technologically sophisticaed design, the Z-6 program was cancelled due to various reasons, including unsatisfying performance and poor reliability. The failure of the Z-6 program resulted in a serious setback in the development of the Chinese helicopter industry. From 1978 to 1989, the Chinese helicopter industry took part in a series of international co-operations with Western partners.
One significant step from the piston-engined helicopter to the tuboshaft-engined helicopter was taken in the Z-6 program, but unfortunately it was not able to be put into serial production because the improper engine selection and the less safety inherent in a single engine helicopter.
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