As we’ll learn in the next chapter, anything that protrudes from an airplane into the air stream can slow it down. To make airplanes fly faster, engineers sometimes equip them with retractable gear that can be mechanically pulled up after takeoff. With the wheels tucked away, the airplane’s exterior is smoother, and when you’re talking about aerodynamics, smoother means faster.
But not every airplane has retractable gear. The main reason is that the hydraulics and motors that help pull up the gear are heavy and complicated. Heavy airplanes can carry less cargo, and complicated airplanes cost more to manufacture, maintain, and insure. So, smaller airplanes and those that put a premium on carrying cargo are usually equipped with fixed landing gear.
And there you have it: the major parts of a plane that enable it to fly. In the next chapter, we’ll see how these parts work together with the pivot points and the four opposing forces on a plane to produce the magic of flight.