This revised textbook, one in the Aerospace Education II series, provides answers to many questions related to airplanes and properties of air flight. The first chapter provides a description of aerodynamic forces and deals with concepts such as acceleration, velocity, and forces of flight. The second chapter is devoted to the discussion of properties of the atmosphere. How different characteristics of the atmosphere help make flight possible, how man can harness the air for flight, and several other questions related to balancing of forces in the air are discussed in chapter two and three. The discussion in the fourth and fifth chapters centers on how aircraft move through the air. The next two chapters discuss the aircraft structure and various kinds of instruments used to control flight. A brief description of navigation instruments is also included. The book is designed for use in the Air Force ROTC program. (PS)