I've been asked the question three times in the past hour: Why can't they just put shields over the engines of airplanes to keep birds from destroying them? In other words, put some dang ol' wire mesh in front of 'em, like they did in the old days. Well, at least the old German days (see photo). I put the question to Russ DeFusco, one of the world's leading birdstrike experts and my main source for birdstrike knowledge over the past six months. Says Russ:
I can't even tell you how often this is suggested to us, but the bad news is it just can't be done. Any kind of defective shield is so disruptive to airflow that modern jet engines just can't operate with them. In order to make such a shield, it would have to be minimally intrusive and thus not able to withstand an impact. In fact, such a shield would likely collapse and itself be drawn into the engines and thus cause even more damage. The answer has been incorporated into almost all modern jet engines: a high bypass ratio. Most air bypasses the core of the engine and is redirected, forced down, and used as thrust and for cooling. Only a portion (usually less than 20%) is used for combustion in the core. Therefore, most debris, including birds, is shunted to the perimeter of the engine and bypasses the core. Unfortunately, birds and other debris when they hit the fan blades sometimes cause those blades to fail and they in turn are ingested along with the bird remains. This, along with the inherent instability that results is usually the cause of an engine's demise in such events.
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