Aircraft for Amateurs
Angle of Attack (AOA) The angle between the wing and the relative wind. When all else is held constant, an increase in AOA results in an increase in lift. This increase continues until the stall AOA is reached then the trend reverses itself and an increase in AOA results in decreased lift.
Angle of Attack.
Ailerons -- Located on the outer part of the wing, the ailerons help the airplane turn. Ailerons are control surfaces which are used to change the bank of the airplane, or roll the airplane. As the ailerons hinge down on one wing, they push the air downwards, making that wing tilt up. This tips the airplane to the side and helps it turn. This tipping is known as Banking. They are manipulated from the cockpit by moving the control column (stick) left and right. Right movement rolls the airplane to the right and vice versa. Roll speed is proportional to the amount of stick deflection. Once a desired bank is attained, the stick is centered to maintain the bank.
Bank -- The angle between the wings and the horizon, as viewed from the rear of the airplane. An airplane with its wings level has zero degrees of bank.
Banking -- Pushing the control stick in the cockpit to the left or right makes the ailerons on one wing go down and the ailerons on the other wing go up. This makes the plane tip to the left or right. This is called Banking. Banking makes the plane turn. Like a bicycle, the plane tilts, or banks, as it turns. This process is also called Roll.
Control Stick -- The ailerons are connected to the Control Stick which is located in cockpit. Pushing the stick to the left or to the right makes the ailerons on one wing go down and the ailerons on the other wing go up. This makes the plane tip to the left or right. This is called banking. This tipping is also called roll.
Drag -- One of the four basic principles of flight. Drag is the force encountered as an airplane pushes through the air, which tends to slow the airplane down. There are two types of drag, and an airplane must fight its way through both kinds of drag in order to maintain steady flight.
- Profile or parasite drag is the same kind of drag experienced from all objects in a flow. Cars, rocks, and hockey pucks must all overcome profile drag. This type of drag is caused by the airplane pushing the air out of the way as it moves forward. This drag can easily be experienced by putting your hand out the window of a moving vehicle (experienced en masse if your hand encounters something more dense than air).
- The other type, called "induced drag," is the result of the production of lift (you can't get something for nothing!). This drag is the part of the forceproduced by the wing that is parallel to the relative wind. Objects that create lift must also overcome this induced drag, also known as drag-due-to-lift. Skin friction is a function of the surface area wetted by the airstream. Any increase in surface area will increase skin friction drag. The other component of profile drag is pressure drag. Pressure drag is a function of the size of the wake behind an object in an airstream; it can be reduced by streamlining the object in order to delay separation of the flow. A side effect of streamlining is an increase in the wetted (exposed) area and hence the skin friction, so it is important to ensure that a net reduction in drag is actually achieved when adding streamlining.
Elevators -- The Elevators are movable flaps attached to the horizontal stabilizer used to change the angle of AOA of the wing which will, in turn, change the pitch, moving the airplane up and down. It is operated by moving the control stick forward or backward, which in turn moves the elevator down or up, respectively. When the pilot "moves the stick forward to make the trees bigger and back to make them smaller", it is the elevator that does the work.
Flaps -- Located on the inner part of the wing, the Flaps help the plane fly slower. This helps to increase the lifting force of the wing at slower speeds, like during takeoff and landing. These slower speeds make takeoff and landing distances shorter. The Flaps slide back and forth, and are controlled by a lever in the cockpit. Flaps are moved down from a streamlined position to increase the amount of lift produced at a particular airspeed.
Fuselage -- The Fuselage is the central "body" of the plane. The wings, tail and engines are all attached to it. In a modern passenger airplane, you sit only in the top half of the Fuselage. The Fuselage also houses the cockpit where all the controls necessary for operating and controlling the plane are located. Cargo is also housed in the bottom half of the Fuselage. The Fuselage is generally streamlined as much as possible.
Horizontal Stabilizer -- The horizontal stabilizer is a fixed position airfoil that stabilizes the pitch of the airplane. When a wing produces lift, it also develops a force that tries to pitch the airplane forward. The horizontal stabilizer prevents this unwanted pitch from occurring.
Landing Gear -- On conventional aircraft, the Landing Gear consists of wheels or tires with supports (struts) and shock absorbers which help in takeoff and landing. To reduce drag while the plane is flying, most wheels fold up into the body of the plane after takeoff. On many smaller aircraft, the wheels do not fold up after takeoff.
Lift -- An upward force that causes an object to rise. In aircraft it may be produced by downward-facing propellers, or by a moving wing with an airfoil shape (the specially curved shape of an airplane wing). Lift is one of the four basic principles of flight. Forces are produced by the wing as the air flows around it. Lift is the part that is perpendicular to the relative wind. The other part contributes to drag.
Relative Wind -- The direction that the air is going as it passes the airplane relative to the airplane. Relative wind has nothing to do with the wind speed on the ground.
Propeller -- This part of the plane produces thrust or forward movement necessary to sustain flight. This turning blade on the front of an airplane moves it through the air.
Rudder -- The Rudder, controlled by the rudder pedals, is the hinged part on the back of the tail which helps to turn the aircraft. It is the vertical part of the tail which controls the sideways movement of the airplane, called the yaw. The least used of all controls, most flying can be safely accomplished without it. (One exception is landing with a crosswind; yaw induced by the rudder must be used to keep the fuselage aligned with the runway and prevent an excursion into the grass.)
Stall -- What a wing does when a given angle of attack is exceeded (the stall angle of attack). The stall is characterized by a progressive loss of lift for an increase in angle of attack.
Thrust The force produced by the engines, thrust works opposite of and counteracts drag. Thrust is the forward movement that is necessary to sustain flight. It is one of the four basic principles of flight.
Trim -- When the controls are moved from neutral, it takes a certain amount of pressure to hold them in position in the airflow. Trim gets rid of this pressure and effectively changes the "center" of the controls - or the neutral position where there is no stick pressure.
Vertical Stabilizer -- The vertical stabilizer is the yaw stabilizer for the airplane; it keeps the nose of the airplane (as seen from above) pointed into the relative wind.
Weight -- The force produced by the mass of the airplane interacting with the earth's gravitational field; the force that must be counteracted by lift in order to maintain flight.
- Basic Weight - The weight of the basic aircraft plus guns, unusable fuel, oil, ballast, survival kits, oxygen, and any other internal or external equipment that is on board the aircraft and will not be disposed of during flight.
- Operating Weight - Is the sum of basic weight and items such as crew, crew baggage, steward equipment, pylons and racks, emergency equipment, special mission fixed equipment, and all other nonexpendable items not in basic weight.
- Gross Weight - Is the total weight of an aircraft, including its contents and externally mounted items, at any time.
- Landing Gross Weight - Is the weight of the aircraft, its contents, and external items when the aircraft lands.
- Zero Fuel Weight (ZFW) - Is the weight of the aircraft without any usable fuel. (This is due to structural limitations of aircraft)
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