Forces on the Bird!



All true flying animals and machines have four forces associated with their flight. These forces are lift, weight, drag, and thrust. (as shown in the diagram)

Lift is provided to the bird from the air moving over the airfoil of its wings. (see next tab) This is what counteracts the weight of the bird caused by gravity pulling it earthward.

Because the bird is moving forward through the air it also experiences drag. This is the friction force the air exerts on the bird pulling it backward. This force is counter acted with the thrust component provided by the bird flapping its wings. The thrust component can also be contributed to by the weight force when the bird id descending as shown in the diagram.