Why there are two thrust models of 16 tons and 18 tons for the turbofan 20 to be replaced by the shipment 20

2022-05-22 0 By

As a new generation of military strategic transport aircraft independently developed by China, y-20 has advanced overall performance, but its overall combat strength has not been effectively improved due to the D30KPII engine.However, it is worth congratulating that with the appearance of y-20 with a full replacement of turbofan 20 engine with large bypass ratio, the outside world is full of hope for y-20 after replacement. It is curious about the improvement of comprehensive strength of Y-20 after replacement of stronger engine, especially the changes in maximum takeoff weight, maximum carrying weight and maximum flight range.I was also interested in the new turbofan 20.Rumors about the Turbofan 20 first surfaced at the 2013 Zhuhai Air Show, where the official model was first unveiled and revealed that it was a turbofan engine with a sustained thrust output of between 13 and 16 tons, which is suitable for a Y-20 military transport aircraft with a maximum takeoff weight of 220 tons.Because the thrust weight ratio of large strategic transport aircraft is generally between 0.2 and 0.3, the larger the take-off weight is, the smaller the value will be. Conversely, the larger the value is, the stronger the short take-off and landing capacity will be. For example, the C17 strategic transport aircraft of the United States has a maximum take-off weight of 285 tons and a maximum carrying weight of 78 tons.The thrust-to-weight ratio is just 0.246.For Y-20, its maximum takeoff weight is 220 tons. In order to balance short take-off and landing capability and flight range, the total thrust required for the whole machine with a thrust-to-weight ratio of 0.255 is exactly 56 tons, which is exactly 14 tons of continuous thrust output for a single engine.Therefore, the 13-16 tons of thrust of the turbofan 20 just meets the requirements of the Y-20 installation.However, in terms of the structure of turbofan engines with large bypass ratio, the larger the bypass ratio is, the stronger the engine thrust is and the lower the fuel consumption is theoretically. Therefore, in order to reduce the fuel consumption, the engines of modern civil aircraft have larger and larger bypass ratio, so the diameter of the engine is also larger.Similarly, what is the engine bypass ratio of turbofan 20, which has been installed on y-20?How big is the engine diameter?All are important parameters for the outside world to guess the thrust size, fuel consumption and performance.For example, the C17 strategic transport aircraft of the United States is in the same class as y-20, but it is equipped with four engines with a thrust of 17.5 tons per unit and a lower fuel consumption due to a larger bypass ratio. The final result is that the C17 with a higher takeoff weight and stronger thrust has a longer flight range.So in luck just change turbofan 20 out of the outside world from satellite images of the diameter of the estimate for turbofan 20 size, because is known, the conveyor’s wingspan is 45 meters, if in terms of pixels, carrying 20 pixels between wingspan is 81674, and the change point of turbofan diameter 20 pixels distance is about 4364,That means the engine diameter of a single turbofan 20 is about 2.4 to 2.5 meters, which is exactly the same as the F117 engine on the C17 strategic transport aircraft.Considering that the value of turbofan 20 is the size including the engine cowling, its actual maximum diameter should be about 2.1-2.2 meters, which is slightly lower than the 2.32 meters diameter of F117 engine.That is to say, the actual thrust of turbofan 20 flying on Y-20 is not the estimated sustained thrust of 14 tons, but close to the 17.5 tons of F117 engine, and 16 tons of thrust indicated on the previous display board.In addition, the thrust output value of 13-16 tons was from 2013, and the turbofan 20 had not been formally finalized at that time. Therefore, after so many years, it is not ruled out that the maximum thrust output of turbofan 20 could be further improved through material change and design modification during the development process.Has the speculation, mainly because the end of 2020, responsible for the development and manufacture turbofan 20 xi ‘an navigation send “e net westing” WeChat aboard, public articles issued the lights decayed You are the most beautiful the star “turbofan 20 suspected exposure in the assembly drawing, this is the assembly of the turbofan engine 20 diameter is very big,Still using the method of pixel estimation, its diameter is as high as 2.3 meters, which is slightly larger than the diameter of the turbofan 20 currently installed on the Y-20.And after a certain strength of aeronautics and astronautics university in a paper published, has publicly appeared with a diameter of 2.3 meters, engine maximum output thrust is as high as 18.1 tons of data table, so whether can be turbofan 20 is likely to be in the process of research and development, and other big foreign bypass ratio turbofan engine, through the cooperation of different diameter of turbofan,Is it possible to derive sub-models of 16 and 18 tons with two different thrust classes?For example, CFM56 series turbofan engines, which are most widely used in the field of civil aircraft, have different diameters and thrust versions. For example, the CFM-56-3 engine equipped in B737 is only 1.94 meters in diameter because it needs to meet the minimum ground clearance of the engine naclet of B737.Of course, the maximum sustained thrust is only 13.6 tons.The CFM56-5 engine installed on the A340 aircraft has a larger take-off weight, so the diameter of the fan blade has been increased by 10 centimeters and the maximum thrust has been increased to 15 tons while the core engine and other components remain the same.Then there is the new generation LEAP engine equipped with A320neo, B737MAX and C919. Because the three aircraft models equipped with the engine are different, the fan diameter of the engine is also different. The engine diameter of A320neo is the largest, so the thrust is larger.The B737max has the smallest engine diameter and therefore the smallest thrust of the three models.Therefore, the diameter of the turbofan 20 equipped on the Y-20 is different from that of the turbofan 20 on the assembly line. It is likely that the turbofan 20 has at least 16 tons and 18 tons of two different thrust models under development and production.Many people may think that the turbofan 20 with a slightly smaller engine diameter is produced to adapt to the Y-20 transport aircraft and help improve the comprehensive combat capability of y-20, but what is the meaning of the turbofan 20 with a larger engine diameter and thrust of 18 tons?Actually thrust of 18 tons of turbofan after 20 mass production application scenario is very wide, from military purposes, thrust more turbofan 20, can be used as a new generation of medium tactical transport aircraft – 30 of installed power, because it is a turbofan double design, so in order to improve load and short take-off and landing capability, assembling more engine thrust is a must.At the same time, turbofan 20 with thrust of 18 tons is likely to further improve the real combat strength of Yun20. For example, if the engine with thrust of 18 tons is replaced with yun20, and its overall thrust-to-weight ratio remains unchanged at 0.255, its maximum takeoff weight will reach 283 tons, and its maximum carrying weight will also be increased from 66 tons to 78 tons.It is exactly the same as the C17 strategic transport aircraft in service in the United States. Of course, all these conditions must be able to withstand the fuselage structure of the Carrier 20. Otherwise, after really changing the engine with stronger thrust and taking off according to the maximum takeoff weight of 283 tons, it is likely to crash on the runway or directly fall apart.Second thrust at 16 and 18 tons of turbofan 20 can also be used in civilian areas, such as our country developed by comac C919 passenger jet used or imported engine, if the foreign thetime foreclosures, will directly affect the commercialization of the C919, so turbofan 20 actually can also be used as a backup strategy, to ensure normal C919 commercial progress.