Airplanes are ubiquitous in modern life, making long-distance travel relatively cheap and widely available. Flying is now a luxury that many can afford, allowing quick travel across the country or even around the world. Believe it or not, humanity just started flying in the early 1900s. How far we've come over the past century! The airplane is a bit of a mechanical marvel. Let's consider some of the key parts of modern aircraft.

Navigation

Airplanes are typically equipped with multiple GPS units, similar to GPS for commercial vehicles like trucks. The GPS units indicate the plane's position relative to a map, facilitating travel from one city to another. Planes are also equipped with various gyroscopes that indicate the speed at which the aircraft is traveling. Such information is used to predict flight arrival times.

Airplanes additionally utilize altimeters to measure the altitude at which the vehicle is operating. Pilots use this information to position the aircraft above clouds and any inclement weather. Altitude information is critical for landing the airplane as well. Planes also have several radios on board, allowing pilots to communicate with ground radio towers to help navigate the aircraft.

Propulsion

One of the most noticeable aspects of a modern airplane is the propulsion system. Planes are quite loud. Indeed, bystanders can hear an airplane landing from significant distance away. Planes move quickly as well. The speed of planes is part of how flying is possible, and, quite simply, one of the main reasons that they are prized for travel. Both the noise and the speed of airplanes are a testament to the power of the propulsion system.

There are actually several components of the propulsion system. The most prominent features are the large turbofan engines typically located on the underside of the wings. These massive engines provide the main thrust used to propel the aircraft. These engines are so large, however, that a smaller engine, called an auxiliary power unit (APU), must be utilized to kick-start the large turbofans.

All of these engines require fuel of course to operate. Fuel is stored in a tank in the main body of the plane as well as two additional fuel tanks cleverly positioned in the wings. The fuel is moved to the engines via electronic pumps. These pumps control the amount of fuel flowing to each engine. Additionally, there are redundant fuel lines and fuel pumps so that fuel can still be transferred to the engines in the event that one of the fuel pumps or lines fails during a flight.

Aerodynamics

Airplanes are typically fabricated from light weight but strong materials like aluminum. The material is constructed into shapes that are aerodynamic, manipulating air to flow in advantageous ways around the craft at high speeds. These features are often taken for granted and go unnoticed, but they are extremely important for flying.

The cross-section of the wings, for example, are shaped such that air passes more quickly over the top of the wing than over the bottom of the wing. The fast-moving air creates an area of lower pressure above the wing, while the relatively slow-moving air underneath the wing creates an area of higher pressure. The area of high pressure below the wing wants to move toward the area of low pressure above the wing to maintain equilibrium, creating a force pushing up on the underside of the wing. In effect, the shape of the wing creates a pressure differential that leads to the force of lift, allowing the aircraft to fly.

The contours of the rest of the aircraft are constructed such that air passes over them with little resistance. These shapes reduce drag force and improve the fuel efficiency of flying. Flaps on the wings and tail of the plane can be used to deliberately disrupt the air flow patterns, allowing pilots to ascend, descend, or even slow the aircraft down during landing.

Airplanes are an impressive engineering accomplishment. They allow humanity to remain connected even over long distances. Having learned a little bit about how planes work, hopefully they can be further appreciated.