新型战斗机研制周期越来越长.费用越来越高,而电子技术和机载武器发展速度远快于飞机平台本身,更新周期越来越短。因此,世界各国都十分关注对现役第三代战斗机进行改进,主要的手段包括改装有源相控阵雷达和采用第四代空空导弹。目前第三代战斗机大多是在20世纪70～90年代服役的,总数量应在6000架以上。近10年来,包括欧洲的“台风”、瑞典的JAS39“鹰狮”和法国的“阵风”在内的“三代半”战斗机也陆续投入使用。本世纪初,典型的第四代战斗机F-22已经进入战斗序列,F-35正在工程研制阶段。但是由于F-22过于昂贵,装备数量 The development cycle of the new fighter is getting longer and longer, the cost is getting higher and higher, and the development speed of electronic technology and airborne weapons is much faster than that of the aircraft platform and the update cycle is getting shorter and shorter. Therefore, all countries in the world are greatly concerned about the improvement of the third-generation active combat aircraft. The major measures include the modification of active phased-array radar and the adoption of the fourth generation of air-to-air missiles. Most of the third-generation fighter aircraft are currently in service in the 1970s and 1990s, with a total number of more than 6,000 aircraft. In the past 10 years, the “Three-and-a-half” fighter aircraft including “Typhoon” in Europe, JAS39 “Gripen” in Sweden and “Gusts” in France have also been put into operation. The beginning of this century, a typical fourth-generation fighter F-22 has entered the battle sequence, F-35 is engineering development stage. However, due to the F-22 is too expensive, the number of equipment