Fast And Low In Jets?

[guclu]

You are correct about your ideas.

Considering bird strike the force applied to the a/c is

F (force) = k (constant) x m (mass of bird) x V x V (speed of bird plus the a/c; hence neglect the speed of bird)

So speed has a squared effect on the impact. And if we calculate :

250 kts = 128 meters/second
300 kts = 154 meters/second

So for k = 1 and mass of bird = 1 kg the forces are (just to see):

F(250 knots) = 1 x 1 x 128 x 128 = 16384
F(300 knots) = 1 x 1 x 154 x 154 = 23716

One more disadvantage is the a/c becomes to act like in turbelence if you increase your speed at low altitudes near Vmo. So that is also not good for passenger comfort and also the a/c.

But on the other way, most of the birds live below 6000feet., and some very busy areas (London, Paris, Schipol, ...) can not let you climb above 10000 but they want you to deliver to the next sector as soon as possible so they let you fly at speeds above 250Kts. Also during your approach for sequencing they might require you to fly greater than 250.

Hope it helped.

Guclu Ulgenalp