On July 26, 2020, China’s self-developed large-scale firefighting/water rescue amphibious aircraft "Kunlong" AG600 successfully achieved its first flight at sea near Qingdao, Shandong, and conducted sea test flight training and verification of aircraft related performance for the next step. Foundation.

　　At 9:28, the first aircraft group consisting of captain Zhao Sheng, co-pilot Liu Ruqin, mechanic Wei Peng, and monitoring observer Jiao Lianyue, taxied an AG600 from Shandong Rizhao Shanzihe Airport. After about 28 minutes of flight, it arrived over the sea near Qingdao.

　　AG600 gradually lowers its height and enters the sea smoothly. It entered the water at 10:14 and took off at 10:18.

　　After completing a series of actions such as turning, adjusting the direction, accelerating, raising the nose, and so on, like an oriental dragon, once again rose into the sky against the waves, plunged into the sky, and successfully completed the sea take-off.

　　After completing the scheduled flight test subjects, the AG600 aircraft just landed smoothly at Rizhao Shanzihe Airport and successfully completed the first sea flight test mission, and significant progress was made in model development.

　　As one of my country's "big aircraft family", the large amphibious aircraft AG600 is the first large-scale special purpose civil aircraft developed to meet the urgent needs of forest fire fighting and water rescue. It is a major aviation equipment urgently needed for the construction of the national emergency rescue system.

　　At present, the AG600 aircraft has completed more than 360 hours of scientific research and test flight, accumulated and obtained a large amount of flight test data, combined with ground test verification, the development team has carried out key design theories, design methods, and verification methods for amphibious aircraft gas and hydrodynamic fusion. The revision and perfection further broke through the key technology of amphibious aircraft design.

　　The AG600 project was officially launched on September 5, 2009. On December 24, 2017, the maiden flight on land was successfully completed at Zhuhai Jinwan Airport in Guangdong; on October 20, 2018, the maiden flight by water was completed at Hubei Jingmen Zhanghe Airport. In order to verify the maritime characteristics of the AG600 aircraft, after the successful completion of the first flight on the water, a series of tasks including scientific research flight test and test pilot modification training were carried out in 2019.

　What can AG600 do?

　　AG600, also known as "Kunlong", is currently the largest amphibious aircraft under research in the world. It adopts a cantilever upper single wing, a retractable landing gear for the first three points, and a single-hull amphibious aircraft layout. It is equipped with 4 domestic turboprop 6 engines, 37 meters in length, 38.8 meters in wingspan, and 12.1 meters in height. (The external dimensions are equivalent to those of the Boeing 737) and the maximum take-off weight is 53.5 tons.

　　The AG600 aircraft is developed in accordance with the design concept of "Amphibious Amphibious, One Aircraft and Multiple Types". Its biggest feature is that it can take off and land on land as well as on water. AG600 can repeatedly throw water back and forth between the water source and the fire site to extinguish the fire. It can not only draw water from the water surface, but also inject water at the land airport. It can carry up to 12 tons of water, and the single water throwing area can reach more than 4000 square meters. With a high wave-resistant hull design, in addition to low-altitude search on the water surface, it can also be anchored on the water surface to perform rescue operations. The water emergency rescue can rescue 50 people in distress at a time. While meeting the requirements of forest fire fighting and water rescue, necessary equipment can be modified according to the needs of users to meet the needs of other special tasks.

　What is different about the first flight at sea?

　　On October 20, 2018, the first water flight was completed at Zhanghe Airport in Jingmen, Hubei. So, what is the difference between the first flight over water and this first flight at sea?

　　The "water" of the two first flights was different.

　　First, the salinity of water is different. The first flight over the water is carried out on the lake. The lake is natural fresh water with relatively low water salinity, which has little test for corrosion protection of aircraft systems; while the first flight at sea is carried out at sea, the salinity of seawater is significantly higher than that in the lake. , More corrosive, therefore, the marine environment has higher requirements for anti-corrosion of the testing machine.

　　Second, the density is different. The density of sea water is high, and the density of lake water is small. There will be differences in the buoyancy of the aircraft in the water and the "stickiness" of the water that needs to be overcome when taking off. And this difference will be more obvious when the aircraft is taxiing at high speed, especially when it is landing, under the same flight conditions (flight weight, flight attitude, flight speed, descent rate, etc.), the seawater density is 2.5% higher, and the aircraft is landing on the sea The reaction force of seawater on the aircraft is larger than that of lake water. This difference will make pilots feel that it is "harder" than fresh water.

　　Third, the waves are different. Inland lakes are generally wind waves formed by the wind, which are short and broken waves with relatively small wave heights, and the wave propagation direction is generally consistent with the wind direction. When planes take off and land on the lake, they usually choose to take off and land in the wind and waves. As the saying goes, "three-foot waves without wind on the sea", there are many types of waves on the sea (wind waves formed by wind, swells formed by overall underwater movement, large boat waves, etc.), waves are high and have high energy, and different types of waves may be at the same time Exist, and the direction of propagation is inconsistent. At the same time, the sea surface is also accompanied by ocean currents and wind, which will make the flight environment more complicated.

　　In addition, the visual experience and control requirements of the pilots were different in the two first flights over water. On the one hand, the sea is more open than the lake, and it is not as easy for a pilot to choose a reference point when landing. On the other hand, the sea environment is relatively more complicated than the lake environment. During the flight test, the wind direction, wind speed, ocean currents and surges, as well as the combined effects of high temperature, high humidity, and high salt environment, need to be fully considered during the flight test. Take off and landing at sea will stabilize the plane's wave and sea taxiing. The requirements for performance, handling characteristics, wave resistance, splashing characteristics, and anti-corrosion characteristics are higher, and the professional operation requirements for pilots are also more stringent, and the corresponding sea test flight support is more complicated.

　　For the first flight over water and the first flight at sea, the verification content of the aircraft test flight is different.

　　The wave height on the lake is small and the energy is small. The first flight over the water is mainly to verify the working conditions of the aircraft’s various systems on the water surface, and to initially check the aircraft’s water surface take-off and landing maneuverability characteristics and performance, providing for the subsequent use of the aircraft for forest fire fighting and natural disaster prevention stand by.

　　The first flight at sea mainly examines the aircraft's take-off and landing characteristics under sea conditions, and examines the working conditions of the aircraft's various systems in the marine environment, and focuses on verifying the aircraft's ability to resist waves and corrosion prevention and control at sea. At the same time, in view of the corrosion protection problems caused by the high-salinity and high-humidity environment of the ocean, the aircraft anti-corrosion effect is evaluated, and the aircraft will be prepared for the future needs of the aircraft to perform tasks such as offshore cargo transportation and water emergency rescue.

　　(CCTV reporter Cui Xia Li Xia Li Ning Tao Jiashu Wu Tianbai Qingdao Taiwan Aviation Industry Group Shi Xia Dai Haibin Wu Bingqi)