（ZT）F-35：发动机叶片 bummer（图）

  

喷气机发动机叶片是在高温和高压的环境下工作的部件，因此不是一般的工程材料知识可以想当然滴，而且还有高速，还是旋转的高速，因此喷气机发动机叶片不仅经受压力还要经受拉力，特别是还有震动，而且还都是周期性的。

其实这些都还不是问题，问题是为了尽量提高发动机的功能，还要尽可能的减小喷气机发动机叶片的重量，因此叶片就做的尽可能的薄，有的部位甚至是空心的，减轻重量也便于降温。

但是，机械毕竟是死的，因此一般机械设计的最佳运作条件或状态不是它的最大指标的状态，因为这时所有零部件都要承受最高的考验，也不是它的比较低的指标的状态，比如说汽车发动机，速度低就有燃烧不够干净的问题，比较中速是比较理想最佳运作条件的状态，其实人体也差不多，慢走有时更累人。

所以，大家可以想象，如果你推一下极限，设计指标还是可以提高滴，但是可靠性和寿命就会降低，也许F-35的发动机没推极限，但是也可能是F-35的性能要求F-35的发动机经常作长时间和高强度的运行，F-35的“发动机叶片 bummer”的外号就出来。

“bummer”不好翻译，我搜了一下，“bummer”的意思差不多就是“糟糕”、“坏消息”、“无赖”、“懒汉”等等。

不知道是F-35因为发动机的叶片不好而不好的，还是发动机的叶片因为F-35不好而不好的，唉，大家自己看吧

请看：

F-35：发动机叶片 bummer（图）

这是2007年测试F-35发动机的叶片断裂照片

  

F-35: Blade Bummer

The news that the Pentagon’s fleet of 51 F-35 fighters has been grounded because of a half-inch crack in one of its engine’s turbine blade is one of those problems that can truly be called a teething issue: it’s something that happens on most every high-tech jet engine that is pushing the engineering envelope.

Pentagon officials over the weekend suggested waiting for Pratt & Whitney, the maker of the F-135 powerplant that powers the F-35, could take a week to 10 days.

Sometimes such problems are natural; sometimes not.

All involved want to make sure that whatever caused the crack is unique to that particular blade and not a threat to all F-35 engines. A single-engine warplane like the F-35 could be doomed by a disintegrating turbine blade.

This isn’t a new problem with the F-35 powerplant; a similar blade cracked during testing in 2007. “Most likely root cause is resonant response to aerodynamic excitation by the upstream 54 vanes in STOVL operation,” an investigation into that earlier failure concluded. “No indication that defects in material properties or single crystal orientation significantly contributed to the failures.”

News of the grounding comes at a sensitive time, as F-35 advocates try to convince the Australian government this week to stick to its original plan to buy 100 of the jets. The grounding is only the latest in a series of problems for the program, which has been plagued by delays and cost overruns.

The U.S. military plans on spending $396 billion for 2,457 of the planes, making it the most costly weapons system in the history of the world (the planes, built by Lockheed Martin, are slated to cost $332 billion; Pratt’s price for the engines is projected to be $64 billion). But the program’s problems, and looming defense-spending cuts, are likely to cut the program, perhaps by as much as half, defense officials say privately.

The grounding affects the F-35s being built for the Air Force, the Marines and the Navy because all three variants use the same engine (“Putting all your engines in one basket,” one defense official says). There had been a plan to develop competing engines for the F-35 – as there were for the older F-15s and F-16s the F-35 is slated to replace – but the Pentagon and Congress agreed two years ago to scrap an alternative engine, saying it wouldn’t be worth the added investment.