How does an airplane waste energy?
An airplane wastes a lot of energy to overcome the force of friction.
The force that opposes the relative motion is called friction. Similarly, in fluid friction, airplanes or birds waste a lot of energy as they have to overcome the force of friction. The force of friction is too great that it slows down the speed of an object to a large extent. Thus, airplane loses a lot of energy and they have specific shapes to reduce the force.