Why is the plateau area a restricted area for air force helicopters?

1July, 984, during the honeymoon period between China and the United States, the two sides signed a contract to buy 24 S-70C civil Black Hawk helicopters. The contract includes 24 Black Hawk helicopters with a unit price of US$ 6 million, 3 sets of external auxiliary fuel tank systems with a unit price of US$ 780,000, and tools and spare parts required for helicopter maintenance, with a total price of US$ 65.438+US$ 50 million. China purchased the Black Hawk helicopter to meet the transportation demand in plateau area. Most of the frontier posts of the People's Liberation Army on the Tibetan Plateau are above 4,000 meters above sea level, with snow all year round, harsh climate and complex terrain, which makes border patrol and material supply very difficult. At that time, there was no helicopter in China to provide assistance to the frontier post in such a harsh environment, so we had to turn to the American Black Hawk helicopter. Up to now, Black Hawk is still the best helicopter in plateau.

The Black Hawk helicopter exported to China was customized by Sikorsky Company according to the requirements of China. In order to adapt to the complex environment of the plateau at an altitude of 4000m, the Black Hawk helicopter exported to China has been strengthened in power and airframe materials. The engine adopts CT7-2C turboshaft engine with increased thrust, and the output power reaches 1285kW. The fuselage is made of many advanced materials including 7075-T6 aluminum alloy. The maximum flight speed of this aircraft is 290km/h, the service ceiling is 5790m, the maximum takeoff weight is 9 185kg, and the cabin can carry 12 ~ 14 people. The external cargo hook can lift 3 tons of weight.

After joining China, the Black Hawk helicopter showed remarkable combat effectiveness and made great contributions to China's border posts in high altitude areas of Tibet. High attendance, long-term use in the Qinghai-Tibet Plateau with bad meteorological conditions, naturally increases the probability of accidents of Black Hawk helicopters. At present, there are only 20 Black Hawk helicopters left in China, and the other four have crashed.

Due to the embargo imposed by the United States on China, it is impossible for China to continue to buy this classic helicopter from the United States. In order to ensure the supply of the plateau frontier post, it is extremely urgent for China to independently develop a helicopter which can perform plateau tasks and has the function similar to "Black Hawk". 2065438+At the beginning of September, 2003, some netizens photographed a new helicopter in a state of disassembly and transportation on the expressway. Its outline is similar to that of the American Black Hawk helicopter, and later it is inferred that it is a domestic paper 20 helicopter. For the first time, Zhi 20 unveiled the mysterious veil to the vast number of military fans in this form. At the end of that year, it successfully made its first flight at an airport in Northeast China. The success of the first flight of Zhi -20 indicates that China has finally filled the blank of domestic 10-ton medium-sized general-purpose helicopter. According to experts' analysis, the future Zhi -20 will become the main force of China's future general helicopter equipment, insert wings for our army's flight and become a veritable flying legion.