Physical Science - Other

# Axis of an Aircraft in Flight

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I had always been awed by airshows or even by war movies with jet fighters chasing each other on highly mountainous areas risky enough to cause collision with another aircraft or with high land areas. The artistic maneuvering of the pilot is a big reason to get an unending clap offering and appreciation from the spectators. But how can these skillful pilots direct their aircraft to do such tricks?

The reason behind these maneuvers is that aircrafts are designed to move in different axes depending on what is needed on a certain situation. The directional movements of these aircrafts can be explained by the axes of rotation which include longitudinal axis, lateral axis and vertical axis. Below is a detailed explanation of these axes of aircraft in flight for us to fully understand how those maneuvers are done.

THE LONGITUDINAL AXIS: ROLLING MOTION

The longitudinal axis is the line drawn from the nose to the tail of the aircraft. If the ailerons present on both wings of the airplane functions antagonistically such that if the left aileron on the left wing deflects downward and on the right wing it deflects upward, it would cause the aircraft to roll .The difference in the configuration created by the difference in deflection of ailerons in the airfoil would cause a difference in lift, thus, causing the rolling movement of the aircraft.

Modern aircrafts, however, do not depend only on ailerons. Some aircrafts now use spoilers which were once used in slowing down the aircraft as well as in decreasing the bottom airfoil pressure when the aircraft is ready for landing.

THE LATERAL AXIS: PITCHING MOTION

The side-to-side or the line drawn from one wing tip to another, perpendicular to the longitudinal axis, is the aircraft's lateral axis. The pitching movement or the up and down motion of the aircraft's nose can be done in this axis with the use of elevators that are connected to the horizontal stabilizer in the tail of the plane.

When the elevator controls are pulled backwards, the angle of attack of air on the airfoil is also increased, thus, increasing the pressure at the bottom of the wings. This would cause the plane to pitch up and the tail to be forced downward. This is helpful during the plane take-off.

On the other hand, moving the elevator controls forward would cause a decrease in lift that would result in a nose-down pitch or diving motion of the aircraft. This happens because the angle of attack on the airfoil is decreased as the elevator moves downward, therefore, the pressure on the top of the airfoil is greater than the bottom causing the aircraft to pitch down.

VERTICAL AXIS: YAWING MOTION

The yawing motion is created through the vertical axis which is from the top to the bottom of the aircraft. A yawing motion would be described as the side-to-side motion of the aircraft's nose that is controlled by the rudder. These moveable devices attached at the rear ends of vertical fins of the tail area are moved by utilizing the rudder pedals.

There are two rudder pedals. The direction of the rudder pedal pressed is equivalent to the direction of air deflection but it is opposite with the movement of the tail. So for example, if the pilot presses the left rudder pedal, this would cause air to be deflected to the left and would create tail resistance that would cause it to move to the right.

These are just the basic foundations of explaining the movements of an aircraft. However, due to man's increasing knowledge, many modifications have already been invented with the aim of maximizing the control of aircrafts during flight.

Fixed wing aircrafts or flying wing aircrafts make use of a combination of aileron and elevators called elevons. It functions in the same way as the elevators and ailerons such that when elevons are moved forward or backward, it would also cause the aircraft to pitch up or down or if it is deflected in opposite directions, it would cause the aircraft to roll.

Stabilators, were designed to make supersonic aircrafts possible. This all-moving tail design, by making the whole stabilizer movable, however causes lesser effect on lift for supersonic flights and it also exhibits decreased dragging force. Ailerons could also be used in the stabilator's function just like in modern aircrafts and such design is called taileron.

Some maneuvers cannot depend on one control alone. For example, the yawing motion cannot just be depended on to make a complete turn in an aircraft. There should be a combination of a little tilting and some climbing motion for it to execute such maneuver. The pilot should, therefore, know how to utilize each axis of rotation to be able to manipulate the controls and make an interplay of these controls to make the flight a crazier ride to further amaze the airshow aficionados!

References:

http://en.wikipedia.org/wiki/Longitudinal_static_stability
http://en.wikipedia.org/wiki/Aircraft_flight_mechanics
http://www.thaitechnics.com/fly/control.html
http://www.allstar.fiu.edu/aero/flight51.htm

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