Rediat Abayneh

Basic mechanics of bird flightLift: Its produced by the action of air flow on the wing. In most cases directed upwards (perpendicular to the drag force), opposing the weight of the bird that is pulling it down to Earth. or it may may come from airflow around the bird's body in some species.Flapping: By flapping its wings down, together with the forward motion of the body, a bird can tilt the lift of its wings forward for propulsion.There are other important motions in addition to the bird's forward motion: Twisiting and FoldingDrag:Drag occurs because the fluid and the object exchange momentum when impacting, creating a force opposing the motion of the object.Thrust: Is a force induced in the direction of the animal's flight, opposing the drag force. To fly at a steady speed in a completely horizontal direction, an animal must generate enough thrust to equal the drag forces on it.

http://www.ucmp.berkeley.edu/vertebrates/flight/physics.html (Accessed 08/03/2014)

http://en.wikipedia.org/wiki/Bird_flight (Accessed 08/03/2014)

http://www.n6iap.com/ornithopter/howbirdsfly.html (Accessed 08/03/2014)