Q If bird strikes can cause an engine to stall, why don’t you put a grill or a gitter in front of the engine? That would prevent birds from getting into the engine and fix the problem, right?
A: To explain the reason why you don’t have grilles in front of an engine, let’s take a closer look at how a jet engine works.
How a jet engine works
A jet engine relies on being able to collect a large amount of air, which is then compressed inside the engine’s compressor stages, where at the same time there is a tremendous heating of the air. For the engine to be as efficient as possible, as much air as possible must pass through it.
If a grill or gitter is to be effective
If a grill or gitter is to be effective against birds in the engine, the grill or gitter must have a certain density. Next, you have to imagine that a collision between a bird and an engine probably occurs at a very high speed, which places demands on the strength of the grill og gitter. So we need a dense grille that is very durable.
The problem with having a grill or gitter
Not only will it be very heavy to have in front of the engine, but the airflow will also be severely restricted. Then there will be a great risk of ice forming on the grill or gitter. If ice forms, we have the problem of even less air getting into the engine. You could of course heat the grill or gitter, and in this way perhaps limit the ice formation, but that would mean a significant increase in weight.
With a solid grill or gitter, you can also imagine that the grill or gitter itself could be damaged – and then you might suddenly have metal (from the grill or gitter) getting into the engine. Compared to a (soft) bird, all things being equal, having splinters from the metal grill or gitter inside the engine would be worse.
Birds in the engine
Generally, a single bird or two is not a big problem for an engine to handle. It has to be the really big birds (and many of them) before there is a risk of damaging the engine.
What the industry have decided to do to minimize bird strikes
The way the industry has decided to go is to remove the things that attract birds from the aviation area itself. Next, you typically also have a unit at larger airports that drives out and scares the birds away.
Typically, it is only when the aircraft is below an altitude of approximately 3000 feet (1 km) that there is a risk of contact with birds. That is, typically in connection with take-off and landing. Birdstrikes typically hit many places other than the engine. For example in addition, the wing leading edge or elsewhere on the fuselage. All those places are reinforced on the plane, so that it does not pose a greater risk if there is contact with a bird. A modern aircraft typically moves at a cruising altitude of about 10 km altitude. So that is why they have focused on “securing” the airport area.
Happy landings and best regards
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