Xianglong - Engine
"Xianglong" high-altitude high-speed long-range unmanned aerial vehicles engines are not ideal, resulting in low load capacity and leave a short time, only 10 hours, and the "Global Hawk" is closer to 20 hours, to which it cannot be compared. The future of the advanced low fuel consumption and through special optimization to adapt to high-altitude work of the WS-15 turbofan engine, "Xianglong" mission time will likely increase to 20 to 24 hours, the payload will reach more than 900 kilograms. At the same time, the aircraft can be used at a lower altitude slow flight to improve a specific target monitoring and detail recognition. In the near future, "Xianglong" will become China's "global hawk" and "predator" as a very unique and important part in the Chinese military forces moving from quantitative to qualitative transformation of high-tech army of important changes.
"Xianglong" UAV initially used an old Turbojet-7 engine as the main propulsion, reflecting a major difference of the UAV and the "Global Hawk" class of unmanned aerial vehicles. Turbine-7 engine is China's early F-7 series fighter engine, the maximum thrust of up to 4200 kg, weighing 1 ton. "Xianglong" high altitude lift ratio, it does not need so strong and powerful engine. "Xianglong" maximum takeoff weight is only 7500 kg, while the engine thrust to 4200 kg, pushing weight ratio of 0.56, generally only contained in tactical aircraft have such a high thrust-weight ratio. Weighing 14 tons, the "Global Hawk" uses a 3450 kg thrust level of the engine only.
There are many reasons for this phenomenon, the first Chinese aviation engine industry level is low, the product line is small, with a lack of available products in the 3000~4000 kg thrust level. China's small thrust turbines are only 1700 kilograms of WS-11 thrust, equipped the engine of the K-8 trainer with a take off the weight of 4300 kg, there are smaller thrust, for the cruise missile WS-500. In 2000 kg above the thrust level until 10,000 kg between China does not have a turbofan engine, only a few from the Soviet Union from the early 1960s to introduce imitation of the turbojet engine. Turbine-7 engine air flow close to 60 kg / s, fuel consumption up to 0.98 g / h, close to the "global eagle" engine fuel consumption of 2 times. In addition, due to the engine thrust is too large, high altitude cruise combustion efficiency is not the engine's best work area, fuel consumption is greater. High fuel consumption seriously affected the aircraft's mission time, but in the initial test phase, the use of this engine as a expedient is also feasible.
"Xianglong" UAV power group in accordance with the modular design, can in the future get uplift to the more advanced WS-15 turbofan engine. Of course, the best engine for the domestic ARJ-21 regional transport engine is the United States General Motors CF-34-10A. Modified engine can provide 4185 kg thrust, weighs only 760 kg, the most critical is the fuel consumption of only 0.35 grams/sec. CF-34 is a long-life civilian engine, the reliability is very high. UAV life and airliners can not, "Xianglong" of the body life of only about 2500 hours, and the aircraft are generally tens of thousands of hours or more, the direct use of CF-34 engine is obviously very extravagant. However, it can use this engine downgraded to low-cost cheap version, which would also be very good.
Using a large thrust engine so that "Xianglong" and the United States "Global Hawk" and "Predator" UAV distinction. "Global Hawk" thrust to weight ratio is very low, from the ground to climb to 19000 meters to work the height of 80 minutes or more, and "Predator" climb to 8000 meters altitude will take 60 minutes. Most of these aircraft can only cruise at a single altitude, especially the "Global Hawk" once the implementation of a high reduction to 9,000 meters after the close observation mission, to restore the work to 19,000 meters height it needs more than an hour. The extent of the use of the machine. "Xianglong" UAV with high-speed and high thrust-weight ratio of the characteristics of the implementation of the "Global Hawk" to reduce the height to restore the height of the reconnaissance mission takes only 1/4 of the latter. Therefore, "Xianglong" can be like "Global Hawk" as the operation, access to "Predator" as the identification and tracking accuracy, is a balance between the two of the UAV system.
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