Lesson 8 Introduction
After trying to build a few flying devices, you probably have some idea of that the process of flying can be quite complicated. People were not built for flight; instead, we built machines that enable us to take to the air.
However, birds and some insects have coordinated and carefully engineered structures that enable them to fly. These animals have the same forces of flight acting on them – gravity, lift, thrust, and drag. In fact, through many hours of observing birds, people eventually were able to design and construct the very first airplane.
Science Connection
Some birds do not fly. They do not have the large wing bones and muscles needed for wing movement. Their wings do not generate enough lift to overcome gravity. These birds have adaptations to help them swim or run quickly. For example, penguins have wings which are designed to 'fly' through the water. Cassowaries (living fossils because they are exactly the same bird found in the fossil record) can run up to 50 km/h, and jump 1.5 m into the air from a standing position.
Other domesticated birds like chickens lead inactive lives. The major muscles needed for flight must be used regularly to maintain their size and tone or they quickly atrophy, leading to flightlessness, sometimes in just a few generations.
