Thrust and lift
the flapping of the wings propel the bird forwards
Eagle
By flapping it wings causing enough momentum for the bird to fly.
An albatross can glide over a thousand miles without flapping its wings.
condor
By flapping it's wings like every other bird on the planet.
The bones are hollow and make the bird light and he can fly by flapping his wings.
Iron Birds
it creates thrust
A bird creates lift by flapping its wings Aircraft move by the air moving over the wings (where as birds move by moving their wings around the air)
it is a simulated bird that is a machineIt's an aircraft that flies like a bird - by flapping its wings, as opposed to using rotors - as helicopters do - or fixed wings and engines providing thrust as aeroplanes do.
It is flapping wings.