Bird Strikes

The kinetic energy of the bird hitting an object is

E = 0.5*m*v^2

Let's see, speed is about 200 kts and the bird weight is 4 lbs. That is 103 m/s and 1.8 kg, so we get

E = 0.5*1.8*103*103 = 9550 J

Wow... that is some load for a plexiglas. There is "Plexiglas T3" (trade name) available, which is 22 times tougher than standard acrylic sheet. The following link seems to have some design information.

http://www.plexiglas.com/acrylicsheet/technicaldata

Let's do some additional estimations. If the impact energy is stopped so, that the plexiglas bends 0.2 m (20 cm) and since J = Nm and the energy goes from full to zero, we can now do a raw estimate:

E = 0.5*Fmax*s ->

Fmax = 2*E/s = 2*9550/0.2 = 95500 N ~ 9700 kg !!

Even the average force is about 5000 kg or 5 tons. A very good reason not to have a windshield angle too much with the horizon.

Very hard to say, how thick the plexiglas should be without testing, since the impact angle is also a very meaningfull factor.

http://www.plexiglas.com/acrylicsheet/technicaldata/properties/aircannon

http://www.youtube.com/watch?v=lp7uLTNiGrQ

http://www.f-111.net/articles/Birdstrikes.htm

http://www.sri.com/psd/fracture/bird.html

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