Midflight

The airplane cabin is quiet and tranquil. The giant engines roar outside, creating a hum that lulls everyone into a semi-sleepy state where everything seems somewhat surreal and even the beauty of the setting sun above the clouds doesn't stimulate interest. You lay back with your eyes closed, a thin blanket over your face, as the sounds of other passengers drifts slowly away, filling your dream with images of friendly families on vacation. Flight is the process by which an object moves, through an atmosphere (especially the air) or beyond it (as in the case of spaceflight), by generating aerodynamic lift, propulsive thrust, aerostatically using buoyancy, or by ballistic movement, without any direct mechanical support from the ground. The engineering aspects of flight are studied in aerospace engineering which is subdivided into aeronautics, which is the study of vehicles that travel through the air, and astronautics, the study of vehicles that travel through space, and in ballistics, the study of the flight of projectiles. The only groups of living things that use powered flight are birds, insects, and bats, while many groups have evolved gliding. The extinct Pterosaurs, an order of reptiles contemporaneous with the dinosaurs, were also very successful flying animals. Each of these groups' wings evolved independently. The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; those of insects are hypothesized to be highly-modified versions of structures that form gills in most other groups of arthropods.