$392 billion Lockheed Martin Corp F-35 program

Lockheed Martin F-35 Lightning II

The F-35 program is the Pentagons most expensive weapon system. A fleet of 2,443 aircraft has an estimated price tag of $391.2 billion, which is up 68 percent from the projected costs measured in 2001. Earlier this year, Air Force Lieutenant General Christopher Bogdan, the F-35 program manager, condemned the manufacturer for trying to squeeze every nickel out of the Department of Defense.

Although the warplane is the most expensive combat aircraft in history, its quality is lacking. In February, the US military grounded an entire fleet of F-35 Joint Strike Fighters because of a crack found on a turbine blade on one of the jets, marking the fourth time that a fleet was grounded because of manufacturing problems. In April, Bogdan told a Senate committee that he doubted the planes could withstand a sophisticated cyberattack.

J-31

隐身技术方面，我国空军试飞专家徐勇凌曾表示，歼-31的隐身气动设计、隐身发动机设计、隐身涂层设计均达到了国际领先水平。他同时指出，歼-31在具备隐身能力的同时又具备了相当的载弹量水平。分析指出，由于歼-31采用的是双发设计，进气道分布在机身两侧，因此，弹仓内部容量相较单发设计的F-35可能要宽裕一些。此外，徐勇凌表示，中国人在四代机的研制上还有自己的考虑，既照顾隐身方面的需求，也考虑作为军用对地、对空作战的空地武器挂载、空空武器挂载。这意味着，载弹量方面，歼-31相比F-35将占上风。

谈到歼31性能是否堪比美国F-35战机时，宋心之表示，现在还不好直接这么比，得官方公布它的试飞数据，才能和F-35比较。但是，歼31有以下几个优势：第一，它用现成的发动机，两台涡扇-13，在发动机上的风险上大大下降了；第二，它的气动布局是后尾式的，像F-22缩小版和F-35双发版的结合体，在气动上的风险也不是很大；第三，它同时借鉴美国第四代机的设计经验，隐身特性较好。第四，它用的技术成熟的发动机，速度比较快，在价格上很有竞争力。