Flight test story behind the first flight of Kunlong ag600

 Flight test story behind the first flight of Kunlong ag600

As the air weapon of the national emergency system, the amphibious aircraft Kunlong ag600 is the first large-scale special purpose civil aircraft developed to meet the urgent needs of forest fire-fighting and water rescue in China. Ag600 aircraft, together with C919 and yun-20, are called three swordsmen of domestic large aircraft, which is another major scientific and technological achievement of Chinas aviation industry by adhering to independent innovation.

On December 24, 2017, ag600 made its first flight on land in Zhuhai, Guangdong Province; on October 20, 2018, it successfully made its first flight on water at Zhanghe airport in Jingmen, Hubei Province. The first flight on the sea is a progress made on the basis of the first flight over water, which has promoted the airworthiness certification work of ag600 aircraft, and will speed up the filling of gaps in Chinas forest fire fighting and maritime rescue system. Wang Chenghua, chief flight engineer of ag600, said.

A plane from the final assembly to the delivery of the use of several years of flight test work, in order to make the aircraft in the most stable flight state, to ensure the accuracy and science of the aircraft flight results. In developed countries of aviation industry in Europe and America, the relationship between flight test cycle and development cycle is 1:1.

The test flight of ag600 is the first comprehensive, complete and systematic test flight of large amphibious aircraft in China, which is a milestone in improving the flight test system in China.

The seaplane was the leader in the 1920s and the late 1950s. At that time, the stability of the aircraft was relatively poor, there were not many land airports and the runway condition was poor, which provided a good development space for the seaplane which could take off and land without the help of landing gear and land. In 1976, the first self-developed water anti submarine bomber shuibang-5 of new China succeeded in its first flight. The test flight was completed by a Navy team without a full-time sea plane test pilot.

After more than 40 years of gap, China has developed amphibious aircraft again, and the test flight task falls on the shoulders of the aviation industry test flight center.

It doesnt mean you cant do it. In the development of the aviation industry test center of China National flight test team for more than 60 years, it has achieved many breakthroughs from 0 to 1. Relying on the spirit of loyal responsibility, realistic innovation, justice and strictness, tenacity and Fortitude, Chinas aviation flight test technology has achieved leapfrog development from military aircraft, civil aircraft to special purpose civil aircraft, and escort Chinas wings flying in the sky.

Flying between the sea and the sky

Drive, slide out, take off Under the pilot pilot Zhao Shengs operation, ag600 aircraft successfully stepped up from the sea. As the captain of the ag600s first flight on water, Zhao Sheng has piloted the plane to the surface of the water for many times. However, for the first flight on the sea, Zhao Sheng and the test flight team arrived in Rizhao, Shandong Province on June 26. According to the requirements of the first flight on the sea, Zhao Sheng made preparations to familiarize himself with airspace meteorology and hydrology.

On July 26, the crew of the amphibious aircraft ag600 successfully made its first flight at sea and took a group photo after returning to Rizhao shanzihe airport. Photo by Wang Kai, a reporter from Xinhua News Agency

The sea flight test environment is complex and there are many uncertain factors, which makes it more difficult than the sea test flight. It is necessary to overcome the impact of special natural conditions such as high sea water density, ocean current and surge on aircraft control. If taking off and landing on land is riding on ordinary level roads, then taking off and landing at sea is like riding on icy roads, and reaction, decision-making and all kinds of manipulation must be very timely, Zhao said

Chen Ming, who has been engaged in flight test for 25 years, participated in the first flight of ag600 on land and on water. In his opinion, what the test pilot has to do is to show all the capabilities of the aircraft through his own technology, and evaluate whether the aircraft can fulfill the tasks it should undertake. This requires pilots to have the ability to learn, evaluate and communicate.

In the face of the new amphibious aircraft, the first thing the test pilots had to do was to learn, but at that time, the domestic technology and equipment did not have the training conditions for water flight test. In fact, only Canada, Russia, Japan and other countries have developed amphibious aircraft. After weighing the teaching conditions, technical level, aircraft type matching and other aspects, the test flight project team finally chose the test flight school in Canada.

In 2015, before the final assembly line of the ag600 aircraft, some members of the test flight project team boarded the plane for Canada. The 4-month training has opened the door for flight test pilots and scientific research teams. For the first time, the flight test team members who have first contact with foreign advanced theories of sea trial flight, special conditions of water airworthiness, and water piloting technology absorb all kinds of knowledge quickly, and compile the learned and collected data into a more than 500 page compilation of translation materials for sea plane test, which is of great guiding significance to the research of domestic seaplane flight test technology.

At the same time, preparations for the first flight on land were also in full swing. As a newly designed large aircraft, during the period when the ag600 flight simulator has not been successfully developed, the test pilots chose the Y-8, which has four turboprop engines and similar size and weight, as the ag600 aircraft to carry out simulated flight training.

Water test flight is more risky than land test flight. Chen Ming said that taking off and landing on water should not only consider the influence of the water environment, but also control the attitude and speed of the aircraft much more finely than the land operation. In order to achieve a perfect landing, the pitch angle control of the aircraft can only be adjusted within the range of two or three degrees. If you dont master it well, the plane will jump on the water like a water float, which may cause the aircraft to stall at low altitude. On the basis of the previous flight test, the flight crew conducted more than 10 low, medium and high speed taxis on the Zhanghe Reservoir in Jingmen, and were familiar with and mastered the water taxiing and take-off and landing characteristics of ag600 aircraft.

One year after the first flight on land, on October 20, 2018, the ag600 aircraft taxied into the water at Jingmen Zhanghe airport, and then rose from the water. After completing a series of established flight test subjects, it successfully withstood the test of the first flight on water.

Sea test flight is a challenge. But at the same time, whether for test pilots or for Chinas flight test system, the first flight at sea is an important opportunity to improve the technology of sea test flight and accumulate experience of sea plane test flight. Zhao said.

Breakthrough from 0 to 1 in water flight test system

At about 10:49 on July 26, 2020, the ag600 aircraft successfully returned to the departure airport after completing a series of established flight test subjects. With the melody of singing the motherland, the plane passed the welcome Watergate, and captain Zhao Sheng reported that he successfully completed the first scientific research flight mission of taking off and landing at sea.

On July 26, the amphibious plane ag600 took off at Rizhao shanzihe airport. Photo by Wang Kai, a reporter from Xinhua News Agency

In the aviation industry flight test center more than 1000 kilometers away, members of aircraft Institute, engine Institute, avionics station, testing institute, modification department and maintenance department of ag600 aircraft test flight project embraced and congratulated each other.

Flight test is a system engineering. If we compare it to a stage play, the flight test crew is the actor in front of the stage, while the teams of aircraft platform, engine, avionics, test and refit, maintenance, flight organization system and model office are equivalent to lighting, props and stage art, and they are indispensable both in front of and behind the stage.

As the chief director, Wang Chenghua once served as the director or deputy chief engineer in the flight test and certification work of J-10, J-11, L-15 and ARJ21-700. Wang Chenghua said that the aviation industry flight test center initially undertook the flight test and certification work of military aircraft. With the development of Chinas civil aviation industry, from Xinzhou 60 to Xinzhou 600 to ARJ21-700, a complete system of civil aircraft airworthiness certification has gradually formed. But the previous flight test and airworthiness certification system were all aimed at land test flight. Before the ag600 aircraft, the water test flight of aviation industry test center was a blank.

Under the command of Wang Chenghua, Wu Chunlin, Zhu Hailong and Dong Wei, the task of filling the gap was initiated by a pioneer force composed of elite soldiers and powerful Generals: Chen Ming, the test pilot, has more than 6000 hours of flight test experience; Xi Chao, the project director of the aircraft Institute, is a post-80s with solid technology and flexible mind; Ma Zhengsheng, the project director of the engine Institute, is launching He has worked in the field of aircraft test for more than 20 years; Zhao Junru, the project director of the navigation point Research Institute, has rich experience in military and civil aircraft flight test; Zhang Bo, a refitting engineer, has done more and said less, and constantly pursues technological innovation

In 2014, the ag600 aircraft flight test project was officially launched. It went to Canada for training, preparing flight test related technical documents, and implementing the pre research project of research on water performance / operation and stability characteristics and mission system flight test technology. Among them, the pre research project involves a number of key technologies of water flight test, such as the research of taking off and landing flight test technology, anti wave index research, rescue / fire fighting mission system flight test technology research, water surface test technology research, etc., and the achievements have become the cornerstone of water flight test in China. Reporter Cai Xinyi, Mao Haifeng

First of all, airworthiness certification flight test needs to determine the applicable provisions and regulations of the aircraft. The water flight test of ag600 aircraft fills many gaps in the water flight test system of civil aircraft airworthiness certification in China.

On July 26, the amphibious plane ag600 taxied over the sea. Photo by Li Ziheng, a reporter from Xinhua News Agency

In China, there were no regulations such as the minimum operating speed of water surface and the speed of leaving water. Xi Chao said that for the purpose of the ag600 test flight, the project team, on the basis of in-depth study on the flight characteristics of seaplane and Chinas civil aviation regulations, combined with foreign training experience, recommended and formulated a number of special conditions, including the minimum control speed on the water surface and the takeoff track on the water surface. At present, these special conditions have been approved by the CAAC, so it can be said that these special conditions have been approved by the CAAC The research provides a legal basis for the water test flight of ag600 aircraft.

After defining the airworthiness standards to be followed by the aircraft, how to verify the compliance between the aircraft and the regulations is another important task. For this reason, on the basis of collecting a large number of domestic and foreign data, and on the basis of simulation and water tunnel test results summary, the project team has completed the research on flight test methods of various subjects on the water surface, providing technical support for the water flight test of ag600 aircraft.

During the flight test, the team also continuously put forward reasonable improvement suggestions to help the ag600 aircraft better achieve the expected goals.

According to Ma Zhengsheng, the domestic turboprop engine used in ag600 aircraft is one of the engines with good stability and obtained the certification of civil aircraft in China. However, the engine is not specially designed for amphibious large aircraft. In view of the water and sea environment, the anti-corrosion and anti salt fog functions of the aircraft should be continuously improved during the flight test.

In 2018, during the land test flight of the project team in Zhuhai, the No.2 engine of the aircraft accidentally stopped in the air. Then, under the leadership of chief engineer Wang Chenghua, the project team immediately analyzed the data. Xi Chao, the project director, first found that all the engine operating parameters seemed to be normal. However, after careful study of the data before and after the shutdown, it was determined that the shutdown was caused by the engines propeller signal. After a detailed analysis of the fault tree, it is found that the failure of the in-flight parking is due to the corrosion of the torque sensor, which causes the engine to send out the propeller signal unexpectedly.

Zhuhai has high air humidity and high salinity, which has a certain impact on the engine. This is the new problem brought about by the change of using environment, Ma Zhengsheng said. in the process of flight test, we should constantly find new problems and eliminate the potential safety hazards under various use conditions.

The successful completion of the first flight on land, water and sea of ag600, a large amphibious aircraft made in China, has achieved a breakthrough from 0 to 1 in the flight test system on water and at sea. This is a big step for ag600 aircraft to be delivered and used, and also a milestone practice in the field of flight test in China. Next, we will work with the R & D team to complete the water supply modification and task system verification, so that ag600 can take on the task of fire fighting and rescue as soon as possible. Wang Chenghua said.

The test flight of ag600, a large amphibious aircraft made in China, is one of the many challenges accepted by the aviation industry flight test center. As a National flight test platform, it doesnt mean that it cant be done. On the contrary, it needs to be done well. Chen Ming said.

Chen has accumulated so much experience in his career for more than 60 years.

On July 26, the crew of the amphibious aircraft ag600 stepped off the plane after the successful first flight at sea. Photo by Wang Kai, a reporter from Xinhua News Agency

61 years ago, a group of young people under the age of 30, in a wilderness, started the cause of Chinas flight test. The Flight Research Institute (now renamed as aviation industry test center) was established on April 15, 1959, making China the fifth country with a complete aviation industry chain of design, manufacturing and flight test after the United States, the Soviet Union, Britain and France.

On July 26, the amphibious plane ag600 taxied over the sea. Photo by Li Ziheng, a reporter from Xinhua News Agency

Under such conditions, the national flight test system has been established bit by bit. With more and more new aircraft test items, the requirements for flight test instruments, equipment, facilities and the quality of test pilots are higher and higher.

In 1994, China test pilot college, which aims to train master pilots, was officially established. Zhao Peng, the chief test pilot of ARJ21-700 aircraft, is the first masters degree graduate of China pilot college. On November 28, 2008, Zhao Peng, as the pilot of test flight crew, piloted Chinas first ARJ21-700 in Shanghai.

ARJ21-700 aircraft, which was approved in 2002, is the first civil aircraft project in China in the 21st century, which is regarded as the shadow engineering of domestic large aircraft. At the same time, ARJ21-700 aircraft is also the first bilateral airworthiness negotiation project between China and the United States, and the test flight is conducted according to the safety and technical standards of American aircraft.

Americans dont trust the Chinese peoples flight test ability. Whether the ARJ21-700 aircraft can pass the test has a bearing on the evaluation of Chinese aircraft test ability by the international aviation industry. Zhao Jie, chief flight engineer of ARJ21-700 aircraft. In this case, Zhao Jie and the flight test team have no other ideas, so they have to go out and do it.

During the most difficult and tense time of flight test, Zhao Jie slept in the office for two winters, directing the flight test team to speed up the flight test process day and night. As many flight test items are carried out for the first time, and many flight test outlines are compiled for the first time. In addition, the review team of CAAC requires 100% spot check of flight test items, the workload of ARJ21-700 aircraft test flight is about two to three times of that of Boeing and Airbus, which is the largest project of civil aircraft test workload at home and abroad. In 2013, all the key technologies of civil aircraft flight test finally made a breakthrough.

Most of the backbone personnel of ag600 aircraft test flight team have experienced the training of ARJ21-700 aircraft project. The successful completion of the ARJ21-700 flight test, the civil aircraft test system has been built from scratch, so that the flight test team in the flight test technology, psychological resilience and self-confidence have been improved. At the same time, many risk subjects of ARJ21-700, including minimum ground speed flight test, maximum energy braking test flight, maximum crosswind resistance test flight and splash test, will basically be used in the flight test of ag600 aircraft.

Test flight paves the way to the sky. More than 60 years of flight test development has proved that a sound airworthiness certification and test system can effectively promote the development of civil aviation industry, otherwise, it will become a hindrance to the development of civil aviation industry. At present, China has formed a model (predictive flight test assessment) before flight, and finally verify the digital and intelligent flight test mode of the model according to flight data, which greatly improves the flight test efficiency and keeps up with the advanced flight test level in the world.

At the same time, a number of young test pilots graduated from famous universities are constantly improving their skills in the professional training system. Jiang Dandan, born in 1989, graduated from northwest Polytechnic University with a masters degree. After more than five years of training, he has become the first female civil aircraft test pilot in China, and has participated in the scientific research and flight test mission of C919. In the next phase of the ag600 flight test mission, Jiang Dandan will also become a member of the team.

I have caught up with a good era. As soon as I take part in the work, I can participate in the flight test and development of large domestic aircraft. This is a good time for all Chinese airlines, Jiang said

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