英语沙龙：高科技神话 隐形航空电子技术（在线收听）

Vaunted Technology: Stealth Avionics

Northrop Grumman Corp．（NGC）boasts on its Web site the B－２spirit stealth bomber is nearly invisible．Because the plane’s composite materials and bat－shaped design make it hard for radar to pick up．However，in １９９９，an F－１１７，which also has a stealthy shape and materials，was blasted out of the sky over the Balkans．Stealth technology is hardly a sham．It shrinks the radar“signature”of a plane．If a conventional aircraft makes a blip on radar screens at ２００kilometers，a stealthy plane wouldn’ t appear until it was ３４km away．The point is，radar does eventually detect the plane．Weather can also present a problem．The B－２’s materials were tested at Edwards Air Force Base，where it rarely rains．But when the high－tech bombers got drenched during missions in the Balkans，the tape used to fill seams in the composite skin often came loose．That en larges the radar signature．

高科技神话：隐形航空电子技术

诺思罗普-格鲁曼公司在自己的网站上吹嘘说，“精灵”B-２隐形轰炸机几乎是看不见的，因为该机的复合材料和蝙蝠形状的设计使其难以被雷达发现。然而以相同形状和材料制造的一架F-１１７战斗机却于１９９９年在巴尔干半岛上空被击落。隐形技术绝不是假的。它能缩小飞机在雷达屏幕上的信号特征。假如普通飞机在２００公里以外时在雷达屏幕上形成一个光点，那么隐形飞机要到３４公里时才会在雷达屏幕上显现。

问题是，雷达最终还是会发现飞机。天气也会带来问题。对B －２材料的测试工作是在很少下雨的爱德华兹空军基地开展的。但当该机在巴尔干半岛执行任务时，遭到雨淋后，用于填充复合材料外壳接缝的胶带往往会松脱，从而扩大了飞机的雷达信号特征。