Physics

Planes Explained Planes can Fly how do Planes Fly Aircraft Fundamentals



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Humans are by nature explorers, seeking to extend ourselves beyond what we can see with the naked eye. In the beginning only birds were able to grace the crystal blue skies overhead, but this temporary limitation was only a matter of time and science. Flight has long captivated scientists and inventors alike, whether it's a person traversing the skies in lawn chair tethered by hundreds of helium filled balloons, or one of many steel behemoths that are capable of carrying massive payloads across great distances, man has always wanted to fly!

The plane is one of many unique inventions that allowed us to soar high above the clouds. Interestingly enough the very first attempts to reproduce what came natural to birds of flight were based primarily upon air and how to harness it to promote flight. A plane was one of the first products of science and engineering that was able to produce simple but effective lift. To better understand how a plane works we must also dispel the basic principles of flight.

What is lift?

Lift is the force that purports flight and prevents a plane from spiraling downward to the ground below. To understand the aerodynamic force of lift it is best to set aside normal logic of gravity and inertia, although these properties also play a vital role in flight. Lift can be described as an invisible hand that pushes underneath the wings of a plane, which is controlled by the amount of airflow above and beneath a wing.

There are some complex mathematical equations that can fully explain the equation of lift versus the opposing force drag, but for the sake of my article I will stick to the fundamentals.

Almost any craft that can fly requires lift to perpetuate flight, but what some may not be aware is the most important ingredient; propulsion. Gliders and other non-powered flying machines require something to create lift, which essentially is wind and gravity. However planes require a propulsion system like a propeller or jet engine to ensure fight is established and maintained.

To create lift you must realize shape is very important and if you look closely at a plane wing you will see that most planes utilize an airfoil shape. The front of the wing is thick and rounded, and the end is thin and tapered and in most designs they have flaps that are used to control the plane. As air passes below and above a pressure is generated that is known as lift.



Propulsion (thrust) explained:

The next component that a plane utilizes is thrust, which is equally important to generate lift. The earliest planes like the first plane designed by the Wright brothers utilized a motor and a propeller propulsion system. Propellers act like giant fans that pull air in a specific direction. The airflow generated is what causes a plane to move forward since the propellers are rotated at extreme speeds. Now the Wright brother's plane didn't reach high velocity like today's planes, but on December 17, 1903, Wilbur and Orville Wright made a sustained, controlled flights in the first true powered aircraft.

Much later planes were utilized for transportation, leisure and during military combat. The earliest planes utilized a singular prop or propeller, however as humans continued on their quest flight also began to evolve. Soon, planes that utilized multiple propellers were used to carry larger payloads. Speed and flight time was also another barrier that became the focus of aviators, which is what brought about the use of jet engines.

Planes were now able to reach breakneck speeds and perform aerial maneuvers that were not though possible with conventional propeller based planes. Even combat advanced to new levels as planes were outfitted with engines capable of reaching Mach rating speeds.

So, now that we understand lift and propulsion we may want to know a bit about the functions of flight also known as the axis.

Axis of flight controls:

To fully understand the axis of aircraft in flight, you have to imagine that a plane has a series of invisible lines that extend from the nose to tail, wing tip to wing tip, and then a vertical line that extends at the intersect point around the center of a plane almost like a cross.

-Roll-

The first line is considered to be the Longitudinal Axis or "Roll". This line begins at the nose cone, traveling through the fuselage of an aircraft and extending just past the tail or aft section of a plane. The Longitudinal Axis or roll is what allows a plane to stay balanced with the horizon or stabilize during landing and take off. The control is determined by the position of the ailerons (flap) that are located on the trailing edge of the wing tips. Each aileron is proportionate to the opposing position, which means; as one is deflecting downward, the opposite aileron moves in the opposite upward direction.
The best way to demonstrate the longitudinal axis is to take a simple paper airplane and make two simple cuts on each of the wing tips. This should create a rectangular tab that can be bent either up or down. If you take the right wing and position the tab downward, and take the left wing and position in the upward position, this will cause the plane to spiral, although most paper airplanes do not exhibit the same properties of a typical airplane due the defined arrow shape and missing tail section.

-Pitch-

The second line is considered to be the Lateral Axis or "Pitch". This line extends from the entire wingspan from wingtip to wingtip. This particular line controls diving and climbing, which is the factor that controls the altitude of the aircraft. By moving the control stick or yolk, either forward or backward it causes the elevators to deflect down or up depending on the position of the stick. The elevator can be found on the tail section of most planes, and it is fixed upon the horizontal stabilizer. These elevators can appear to be attached to a smaller wing that is fixed to the aft of a plane, however some planes such as the F-117 Nighthawk or the Concord use a much more complex method to stabilize or utilize lateral pitch control.

If you want to demonstrate the lateral axis you can revert back to the paper airplane, but now change the elevators or rectangular tabs into equal upward positions. Notice how the paper airplane now appears to float or hold longer flights. This reaction is due to the air being deflected off the tabs, which will cause the lateral pitch to elevate the plane. Unfortunately most designs will not demonstrate perpetual flight due to drag, and size, however if you reverse the tabs, the plane will almost take an immediate nosedive.

-Yaw-

Lastly we have the final axis called the Vertical Axis or "Yaw". This invisible line extends from below the plane, through the center point; possibly the cockpit, all the way to just above the plane. Now, in flying terminology the Yaw is equal to turning, and is controlled by a vertical fin that is fixed upon the tail of a plane. The vertical axis control will affect the heading the plane is traveling by shifting the nose from left to right. The control of the yaw is dependent on two pedals that control either left or right movement of the fin or rudder section of the plane. Only a handful of aircraft such as the B2-Spirit a.k.a. Stealth bomber don't utilize the same form of aft control for Yaw and Pitch, but instead they utilize more complex flap or rudder configurations to aid in air control.

The Axis is what makes flight control possible, and are utilized to properly navigate or to maintain a specific course of flight. The Axis is also a critical component to both the take off and landing process, which ensure that equal contact is maintained during touchdown or lift off. If you ever see a plane during take off or landing, you may see slight corrections on the approach or just before the wheels leave the surface of the ground. This minor correction is so the plane can level off to the horizon line, since the pilot has no other way to view his approach or to see if his wheels are both touching down at the same time.

As a young boy I was always fascinated by planes, helicopters, and just about anything else that took to the air. My first romance began with making my own paper airplane fleet, but soon it grew into a hobby that included my first remote controlled plane. Soon after I joined the Air Cadets and finally had a chance to grab hold of the yolk of a real plane.

Now that the skies are blanketed with aircraft in flight it seems much more common and less mysterious, but don't assume that it is any less complicated. Planes don't defy the natural laws of physics; instead they function solely upon these laws to perpetuate flight.

Now that we all know a bit more about how a plane works we can be a bit more at ease as we slump into our seats and the plane begins to taxi down the runway. Flying is an amazing experience to be shared by all even if the media propagates fear it still is one of the safest modes of transportation. As for me I still have my license, although I never took it professionally, I still like to soar with the birds every once and awhile! See you in the skies!

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