A glider is a special kind of aircraft that has no engine.
Paper airplanes are the most obvious example, but gliders come a wide range of sizes.
Toy gliders, made of balsa wood or styrofoam, are an excellent way for students to study the basics of aerodynamics . The Wright brothers perfected the design of the first airplane and gained piloting experience through a series of glider flights . These aircraft were similar to modern hang-gliders and were launched by running off a hill. The glider's flight path is a simple straight line, shown as the inclined red line in the figure. If we know the distance flown and the altitude change, we can calculate the glide angle using trigonometry.