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Liming WS10A Taihang Engine

The WS10, China's flagship jet fighter engine, remained seriously flawed after a quarter of century of development effort. The WS10 engine was intended to equip the new J-10 fighter, low-rate initial production of which was authorised in 2002. But at least the initial run of fifty J-10 aircraft were to be fitted with Russian AL-31F engines instead. The WS10 engine was reverse-engineered from the CFM-56 commercial turbofan, which in turn was a derivative of the General Electric F101 engine originally designed for the 1960s-era Advanced Manned Strategic Aircraft, which was eventually deployed as the B-1 bomber.

That is to say, after nearly a quarter century development effort on a four decade old design, China remained unable to produce a viable high performance fighter engine. As late as 2007 the Chinese Air Force was still unhappy with the WS-10 engine, with performance and manufacturing quality issues plaguing the project. Photos of J-11B aircraft with the WS-10 engine surfaced in 2009, indicating that most, if not all, of the Taihang engine's problems had been resolved.

The WS-10 is a high power, high thrust to weight ratio and low bypass ratio engine with 12 stage structures, including a 3-level fan, nine-level stator, one-level high pressure compressor and one low pressure compressor. For the development of WS-10, China made almost 300 breakthroughs in aviation technologies and materials, such as transonic turbine, air film cooling blade, integrated fan rotor by electron beam welding, squeeze film damper, metal brush seal, high energy igniter, variable camber inlet guide vanes and convergent / divergent nozzle. The combined cooling blade of turbine used hi-tech materials called Directionally Solidified Eutectic Super-alloy and can stand 5000 time tests without cracking.

In fact, the significance of the WS-10 engine goes beyond the engine itself. Five Permanent Countries of UN Security Council all produce and possess nuclear weapons. But there are only four powers which can independently manufacture modern turbofan for combat aircraft. The absent one is China. The birth of WS-10 was a milestone that China had begun to fill up the blank in fighter engines.

The WS10, designed to power fighter aircraft, was in development at the Shenyang Liming Engine Manufacturing Corporation. The abandonment of the WS-6 project did not mean that China had given up on independent aircraft engine manufacture. In 1980, China started to implement a High Performance Propulsion System Preliminary Development (HPPSPD) plan, to focus on basic research on engine components. On 29 March 1982, Aviation Week & Space Technology published an article entitled "China Waiting for CFM-56II Turbofan Exportation?" The report said that China had purchase 2 CFM-56II Turbofan engines to replace the engines on China's Trident airliners. The US Department of Defense worried about this export, because the CFM-56 was based on the core of the F101-GE-102 engine which was used in B-1B Lancer bomber. Despite this protest, the US government still authorized this export.

Some Chinese sources report the development of the Chinese WS-10 engine was based on the core engine from CFM-56. The CFM56 is a double-body, dual flow turbofan engine (operating in separated flow and multiphase flow) with 10 tons of thrust. The CFM56 family of engines has years of service with many of the world's airlines. CFM56 is a high bypass ratio turbine fan engine, under development since the early 1970s by Snecma Moteurs in France and GE in the USA. The engine's design is flexible in order to meet specific aircraft needs; it consists of four fan sizes, ranging from 60 inches to 72 inches in diameter, and six series, producing thrusts from 18,500 to 34,000 pounds.

The CFM56-2 is the family baseline, offered since 1972. It was the first high bypass ratio turbine fan engine in the 10-ton thrust class, with a 68.3 inch fan diameter. Its three sub-series supply power for the military aircraft KC-135R, C-135R, E-3, KE-3A, E-6A, and DC-8. CFM56-3 was derived from CFM56-2, tailored tomeet the needs of short- to medium-range Boeing 737-300/-400/-500, and the Trident aircraft. The fan diameter is 60 inches, the smallest in the family. Some components were improved, such as the low-noise, low-emission combustor and the elliptical spinner for improved hail/rain ingestion. It has three sub-series, -3-B1, -3B-2, and -3C-1, with thrusts varying from 18,500 to 24,000 pounds.

The General Electric F101 engine was originally developed for the Advanced Manned Strategic Aircraft program, which became the B-1 strategic bomber. Advances in compressor, combustor and turbine knowledge in the 1960s led to the F101 engine, selected for the B-1 bomber. In 1984, the U.S. Air Force selected GE's F110 engine, based on the F101 design, as one of the engines for the F-16C/D fighter aircraft. The F110 also powered F-16s worldwide as well as Japan's single-engine F-2 fighter aircraft and the U.S. Navy's F-14B/D Super Tomcat fighter. A derivative of the F110, the F118, powered the B-2 bomber.

The goal of the WS10A program was to produce a turbofan equal to the Russian Saturn AL31F, which has a thrust of 27,600 lbst and comparable US engines, to power new 4th generation fighters like the and Chengdu J10 and Shenyang J11. The WS-10 project got direct support from top leader of China. In January 1986, Deng Xiaoping passed a new plan on China's turbofan engine development. One year later, the 606 Design Institute (the AVIC I designation of the Shenyang Engine Design and Research Institute), with its attached department, formally initiated the development of the WS-10, code name Taihang, for China's third generation J-10 fighter. In 1989, after almost a decade of preparation, the WS-10 core engine project started. On 12 June 1989, Chinese aircraft engine manufactures received the order for "HPPSPD core test components". In July, a conference of three most Important Parts of High Pressure compressor was held in the 624 Institute. These three parts include: 7-stage high pressure compressor, short annular combustor with air blast atomizer and air film cooling blade. With out these main parts, China's future core engine can not be resolved. In the future, the core engine will be able to become a medial thrust & small bypass ratio turbofan with a thrust to weight ratio of 8. In China aviation industry, this core engine was called as Medial Thrust Demonstration Turbofan Core Engine, MTDTCE.

At the end of 1990, MTDTCE entered the list of 18 Significant SciTech Projects of the COSTIND (Commission of Science Technology and Industry for National Defense) Eighth-Five-Year Plan. In January 1991, the concept argumentation of MTDTCE and medial thrust demonstration engine had been completed. The whole plan included 3 steps: step 1: High Pressure Compressor Components production; step 2, MTDTCE; step 3, demonstration engine. For the first time, China followed a regular way on engine development: basic research technology break through components core engine demonstration engine prototype production. A milestone in China Aviation industry appeared in the 1990s. 624 Institute designed the MTDTCE and the chief designer was Jiang Hefu. MTDTCE's startup was in February 1991 and successively completed in preliminary design and main forgings and castings blueprints. In February 1992, major components machining blueprint was issued to sub-manufacturing plants. To speed the outside pipeline installation of core engine, a metal model of engine was finished in only 4 months.

The manufacturing of MTDTCE was carried by No.403 plant (military industrial plant all use code as name for confidentiality) and involved 21 factories and research departments in China. The trial production was initiated in March 1992. During the proceeding, 7 technologies were breakthrough by Chinese people, like complex directionally solidified blade forging, short annular combustor manufacture, precision forging of diffuser with shaped blade and electron beam welding of compressor. China raised up its technology for 10 years. For 9 months (18 November 1992), the first finished product of MTDTCE left the factory. After the installation of nozzle and accessories, the engine was fixed on the ground testing platform on 24 November. On 03 December at 11:20 PM, the engine was successfully powered on for the first time. On 12 December, in the eleventh test, the engine reached its maximum rotor speed and all testing parameters were normal.

About 2001 to 2002, WS-10 began the flight testing with Su-27 (J-11). In 2003, PLA Daily, official newspaper of PLA, had a report about WS-10 engine. It said: our new Turbofan engine is being tested on China's new fighter (J-11) the fighter is equipped with two different engines, one is made by China, the other is from foreign country. This is the main evidence that WS-10 had been on critical developing stage since 2000.

The J-10 doesn't fly on WS-10A, it flies on AL-31FM imported engines from Russia. The WS-10 is expected to eventually be installed on the J-10 and, possibly, the Su-27s that China is coproducing at Shenyang. According to the 2004 U.S. Defense Department report on Chinese military capabilities, "Recent testing reportedly has attained the standard of the Russian AL-31F." In December 2004, however, a contract was finalized for Russia's Salyut to supply 250 AL-31FN engines for the J-10 (in addition to 54 previously supplied), suggesting that as of 2005 development of the WS-10 had not been satisfactory.

Although WS-10 project got stronger support from government, it was still not smooth to excogitate Turbofan engine in developing country. And china defense enterprises were not recovery from the decline in 1980s and 1990s. Interior quality control and discursive employees often made WS-10 into great troubles. From August to September in 2003, WS-10 here and after performed some quality problems.

Chinas problems with the copycat version of SU-27 AL-31 turbofans isnt about advanced computerized production. The Chinese just cant figure out the alloy composits of making a reliable heat bearing jet engine as yet. Because of this, Chinese copycat engine WS-10 of the SU-27 AL-31 turbofans tend to have blades that crack & break apart sucking debris into the engine. Chinese WS-10 also has shorter lifespans than original AL-31 turbofans because metal alloys in Chinese version reportedly break & cant handle the high heat. Also Chinese WS-10 turbofans have spooling issues with their copycat turbofans. Its a lot more looming problem for the Chinese engineers than just advanced computerized production machinary. Plus the copycat WS-10 of the AL-31 is not powerful enough to allow the feature super cruise ability of F-22, F-35, and the future PAK FA-50 joint venture stealth fighter by Indo-Russo design.

In 2004, a fatal accident almost killed WS-10. At July 20th 2004, a Su-27 fighter (test pilot Ding Sanxi) took off from Yanliang (in Shanxi Province) Airport for WS-10 engine testing. When in flight testing, Ding Sanxi suddenly heard a bang, then the left engine shut down. Pilot Ding Sanxi immediately judged that it was not like old in-flight shutdown accident. According to his experience, Pilot Ding Sanxi estimated that it was mechanical failure then he decidedly drove a single engine Su-27 to land on successfully. After four months investigation, the direct cause is the engine bearing failures. Since the beginning of WS-10 project, over 18 years have been passed and WS-10 had been troubled by bugs, from the mysterious sound to difficult starting in high temperature. To overcome these problems, Chinese people found ideas by their talents and even the bravery of test pilots.

On 11 May 2005, the endurance life test of the WS-10 engine started at 606 Institute, which declared that the project was close to the designed approval of prototype. This period includes two important test-operations: endurance life test and then full life test. In the history of China's engine development, the WS-10 created a series of top records in testing range, programs and time. Those two tests are the most rigorous trials on engine reliability. On 10 November 2005, the WS-10 at last got across the full life test. The WS-10 "waltzed" through a 40 day trial without any failure. The WS-10 project was finally finished after almost 20 years' work.

But as late as 2007 the Chinese Air Force was still unhappy with the WS-10 engine, with performance and manufacturing quality issues plaguing the project. Photos of J-11B aircraft with the WS-10 engine surfaced in 2009, indicating to some that most, if not all, of the Taihang engine's problems had been resolved.

Richard Fisher wrote in 2010 [Testimony for the U.S.China Economic and Security Review Commission Hearing on China's Emergent Military Aerospace and Commercial Aviation Capabilities, May 20, 2010] that "Since the early 1990s Russian sources have disclosed to the author that Shenyang was experiencing great difficulties in meeting planned thrust goals, while there have been reports and rumors of other specific problems. In August 2009 a Chinese AVIC official admitted there were many problems facing the Taihang but declined to elaborate. Other possible issues include incidents of shedding turbine blades, oil leakage issues, and even one unconfirmed rumor of a new J11BS fighter disintegrating in flight due to a Taihang engine failure."

Taihang Mountains

On 25 February 2006 an official announcement from China Aviation Group I stated that the WS-10A Turbofan Engine was formally design certificated and named "Taihang". As usual, the WS-10A engine is named after a mountain in China, like WS-9 is named after "Qing Lin", a mountian near Xian where the WS9 is manufactured. Taihang is a famous mountain in North China.

There are four principal mountain ranges in China, viz.: The Celestial, Himalaya, Nan Shan and Soyoti, all of which have peaks extending above the snow line; besides numerous mountain ridges, which are below the snow line. "Siao Wutni" in a prominent mountain 12,000 feet high, situated in the Taihang range between Chihli and Shansi.

The Tai Hang range of mountains rise abruptly and form the frontier of the province of Shansi. The great plain of China extends from the base of the Tai Hang Tange of mountains easterly to the sea, and southerly across the Yellow River to the Yang-tsze and beyond. Limestone is very generally distributed all over China, overlying the primitive granite, and forming much of the mountain ranges, such as the Taihang shan of Honan. A line of hot springs near the east border of the Taihang Shan extends southward through the Han River Valley to Ichang on the Yangtze Kiang and farther southwest. Many thermal springs are along definite stratigraphic horizons or on local faults. Honan may be well considered the nursery of Chinese culture and civilization. Lying mostly to the south of the thirty-fifth parallel, th'e climate is warmer and more temperate than that of the provinces of Shensi and Shansi to the west and north, being protected from the bitter north-west gales of winter by the Tai-hang range, on the borders of Shansi, on the north, and by the lofty Tsing-ling range of Shensi on the west.

As the Tai-Hang range is covered with loess to a great height (as high as 2000 meters above the level of the sea), and a number of mountain-streams flow down its southern declivities, it is no wonder that the detritus-slope with its gently sinking prolongation, continually overflowed by water full of fertilizing deposit, should spread wider and quicker than the dejection-slope of an ordinary mountain.




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