Physics

How Airplanes Fly



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When I was but a little boy, I remember going to an air show on an Air force base. I never saw a more incredible sight. One thing wandered through my mind though, how could something so big and heavy stay airborne? This is a topic I have learned about throughout school but until recently never went deeper into detail.



My childhood question was answered around the fourth grade. There are four ideas you must understand before we proceed. The first is lift. Lift is the force that allows the airplane to become and stay airborne, It is produced by a lower pressure created on the upper surface of an airplane's wing compared to the pressure on the wing's lower surface. This causes the wing to be "lifted" up. The unique shape of the plane's wing is called the "airfoil". It's designed so that air coming over it will have to travel longer which results in a low pressure zone. Like previously described this creates lift and raises the wing upward.



Another important factor is thrust. Thrust is a force created by a power source that pushes the aircraft forward. Thrust will either push or pull the plane forward. "A good lift/drag ration is one of the most important qualities a aircraft can posses, if not the most important, for it is a quality which epitomizes what every aircraft is intended to do; to lift the maximum possible load with the minimum power (Desoutter 7).



The third force in this series is called drag. This force slows down the aircraft's forward motion when the direction of the airflow is opposite to the direction of motion of the plane. Thrust is the remedy that overcomes drag. Gravity is the final force, which merely weighs down the plane.



Now we know how the plane stays airborne, but how does the pilot control it? This is best explained by describing the plane's segments. Segments found in the plane are the ailerons, rudders, and elevators. Ailerons are inserted in the wings and the rudders and elevators are inside the vertical and horizontal stabilizers. The pilot uses these to control his position from the cockpit. When the pilot moves them into the airstream they cause the plane to react to the air pressure. Plain and simple the pilot uses these controls to go left, right, up, or down. Another thing that helps the plane fly is the propeller. The propeller moves air to the rear(the action) which causes the airplane to go forward(the reaction) (Smith 3).



Pilots are able to change the direction of the plane by using one or more of its three axes of rotation: the Lateral axis, the Longitudial axis, and the Lateral axis. The axis's are imaginary lines that run opposite to each other through the middle of the plane. Pitch, roll, and yaw is the planes rotation around these imaginary lines. Next I'll explain what these controls do.
Yaw controls the rudder's movement on the airplane, which rotates it around the vertcal axis. Roll controls the ailerons, which rotates the airplane around the longitudial axis. Pitch moves the elevators, which rotates the planes around the lateral axis. Each of these controls are essential to the pilot.



Pilots are excellent navigators but that doesn't mean they don't have help. They use certain equipment during flight. "The instruments on the panel of the airship serve as the nerve of the ship" (Weems 1). These "instruments" allow the pilot to know his height, direction, angle, and speed. It also includes a radio and GPS network. This entire set is called AVIONICS. The GPS network is known as the Navstar Global Positioning System. It's a sattelite in space that, through radios provides properly equipped users with highly accurate PVT(position, velocity, time) info. "The GPS was developed by the U.S. Department of Defence as a radionavigation system to be their primary source of navigation" (Clarke 1). The GPS is used by civilians and the military. It can also be used on sea, in air, or near space.
A big factor in flight is the fuel systems. For airliners there are people hired to tend to the plane's fuel systems but private pilots are taught how to take care of the fuel systems, but only because they use small aircrafts. There are four major jobs in tending to the fuel systems. All of these jobs are used on both planes and jets. The first is the storage of fuel. Those who tend to the fuel systems must make sure fuel is safely secured in tanks around the airport. The next job is to distribute the fuel. They must safely transfer the fuel from the tank and into the aircraft. One of the most important jobs is to manage the fuel before and after its loaded into the aircraft. There are indicators that show the level of fuel that is in it and the stability of the fuel. This is an important job of the safety of the plane because if the fuel is unstable than it could set fire or even cause the plane to explode. The last part is to check the engine and turbines, for the jets, to see that everything is working a wires have banding straps, so fires couldn't start from inside.



One last important aspect of the aircrafts flight is the environmental system. This is most obvious on airliner jets. This system ensures a controlled environment inside the aircraft interior, which includes temperature, air supply, airflow, pressure, and humidity.



To keep the temperature controlled they use air conditioner and cooling packs in the pilot and passenger area. HEPA is used on jets which filters out 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 micrometers or larger. They use a recirculation system that monitors and replaces the CO and CO2 levels. Jets have a oxygen mask that automatically pops in front of every passenger when the oxygen level is too low. Planes have an oxygen bag that the pilot and passenger can breathe out of.



This was a short description of the essentials of flight, in fact, you can write hundreds of pages of material on how planes fly, but many parts of this topic is much too complex and detailed to talk about in a single article. Pilots study for years to grasp the basics of flight. I hope through this presentation you understand what makes aircrafts lift into the air and into the great blue beyond.











SOURCES

Clarke, Bill. Aviator's Guide To GPS. New York: Mcgraw-Hill Inc., 1994.

Desoutter, D.M. All About Aircraft. New York: John De Graff, Inc., 1919.

Jeppenson Sanderson, Inc. Private Pilot Manuel. 13th ed. Englewood:Jeppenson Sanderson, Inc., 1995.

Smith, Robert T. How To Fly Light planes. Blue Ridge Summit: Tab, 1978.

Varley, Helen, and Patrick Harpur. The Air Travelers Book. New York: Simon and Schuster, 1978.

Weems, P. V. H., and C. A. Zweng. Instrument Flying. Annapolis: Weems and North Hollywood: Pan, 1957.



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