WP8 -Turbojet Engine with High Thrust
The WP8, which was used for the H-6 medium bomber, was made according to the Soviet RD-3M engine technical documents. This engine was a relatively advanced high thrust turbojet engine at the end of the 1950s. Its maximum thrust is 93 kN (9,500 kgf), which is two times more than that of WP5 and WP6 engines. The weight was 3,100 kg and the maximum diameter was 1.4 m. The series production of such a large engine needed several hundreds of precision, special and large equipment and special test facilities. The production of each engine would consume 15 tons of high temperature alloy and 9.5 tons of non-ferrous metal. The blank of the turbine disc had to be forged by a 10,000 ton class hydraulic press. The manufacture of the high thrust engines reflected the economical strength and industrial level of the country. At that time only very few countries in the world could produce such engines of this size.
In 1958, in order to meet the requirements of the trial production for the H-6, it was decided that trial production of the WP8 engine would be jointly undertaken by HEF, SEF and XEF. In 1961, the aviation industry cut short its front line and trial production was temporarily halted. In 1963, it was decided that XEF would carry out the task alone.
The trial production in Xi'an was led by chief engineer Jiang Zutong and was carried out in plan-ned phases. At the beginning of 1962, the factory sent out 132 staff members and workers to HEF and SEF to study and exchange experiences for the trial production and to accept the documents and materials concerned. From 1963 to 1964, some detailed parts started to be trial produced. In the latter half of 1965, the trial production began in an all-round, way. In order to form the team quickly, the factory assigned some new workers to the WP5A production line and took out the experienced workers to the WP8's. They opened technical training classes for the production technology of the critical parts, and signed the teaching and learning contracts between the masters and apprentices using dummy blanks for training. That enabled the operators to grasp techniques quickly. Then, organized by Ma Shiying, the vice chief engineer, the trial production for 197 critical parts and components and tackling the key technical problems started.
The Soviet Union did not provide the composition and work processes for the first stage nozzle guide vanes (NGV) casting alloy and they developed it successfully with the joint effort with the Beijing Aeronautical Materials Institute (BAMI) and Shanghai Jiaotung University. They also took many measures during the trial production to strengthen the quality control. Thanks to the joint efforts of the people from the top to the bottom and from the inside to the outside of the factory, the WP8 engine passed the State appraisal test in January 1967 and it was put into series production.
Since that time, China has had its home-made high thrust engines and its own factory for making such engines. Its medium bombers had reliable powerplants. This was major progress in 'China's aviation industry. A total of 1,193 items of raw material, forging and casting blanks and finished parts and accessories were needed for WP8 engines. In 1960, about half of them could not be domestically produced. That became a major problem for the series production. The State relied on and developed indigenous materials. In 1967, the majority of problems were solved.
At this stage of WP8 trial production, the first time between overhaul (TBO) was 300 hours. XEF continued to undertake life extension work and gained great achievements. In 1974, the life was approved to be 500 hours, in 1979 extended to 600 hours and in 1983, further-extended to 800 hours.
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