WZ5 Turboshaft engine
In 1966, MAI assigned to Harbin Engine Factory [HEF] the task of modifying the WJ5 engine into the WZ5 engine. The designed shaft power was 1,618 kW (2,200 hp), with a weight of 700 kg and it would be used on the Z-6 helicopter. On this basis, the performance can be further increased and it can be used as a twin-packaged powerplant to provide more power for new helicopters.
The design concept was: to keep the flow path of the WJ5 engine unchanged, and to modify the mechanical transmission and free turbine governor. After intensive hard working, the first prototype engine was put to the running test. In 1968, the Zhuzhou Aeroengine Research Institute (ZARI) was set up. The development of the WZ5 engine was transferred to ZARI. The manufacture of the prototype was still carried out by HEF. HEF and ZARI jointly formed a development team for the follow-up test and design amendments. The 400 hours endurance test was passed at the beginning of December 1969. On December 15, in the cold winds of Northern China, people were crowded along the two sides of the airfield at HAF. They excitedly witnessed the test flight of the first Chinese-designed helicopter to use the turboshaft engine. After solving the problem of the loss of height during hovering in the flight test, the Z-6 helicopter was flight tested from a high airport for the first time in 1970, with excellent results.
In April 1973, the WZ5 engine was transfered to Jiangsu Province for continuous production. The engine passed the State ground test and flight test appraisal in October 1976. The result showed that the WZ5 engine had good performance at high ambient temperatures and on plateau. At Nanjing airport when the temperature was 38 t , it could take-off vertically with 1.2 tons maximum payload; at Gonghe airport in Northwest China, 3,170 m above sea level, it could take-off vertically and hover with maximum payload. Later, the Aero-Product Certification Commission formally certified the WZ5 engine.
Due to the low payload and low level of safety with single engine operation of the Z-5 and Z-6 helicopters, the development of a new helicopter, Z-7, started in 1970. The design of the powerplant was carried out by ZARI. It was decided to use the twin-packaged WZ5A engines, the modified version of WZ5. The take-off shaft power of a single engine was 1,714 kW (2,330 shp). The modification design was finished in the first half of 1971, followed by the component rig tests such as the static stress and rigid tests for the load-bearing case of the free turbine and the zero load running of the elastic coupling, etc.. Because of the disturbance of the " great cultural revolution" , the development work was adversely affected. The 50 hours endurance test was started as late as July 1978, and the performance reached the design target. Later as the development of the Z-7 was cancelled, the further development of WZ5A was also given up.
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