AFOQT Aviation Information

fixed-wing aircraft structure

1. Fuselage

2. Wings

3. Tail assembly or empennage

4. Landing gear

5. Powerplant

6. Flight instruments/controls and control surfaces

fuselage

body of an airplane. Contains the cockpit, the cabin, the cargo area if there is one, and attachment points for other major airplane components, such as wings, tail section, and landing gear.

cockpit

from which the pilots and the flight crew control the aircraft's operations

Two design types of fuselage construction

1. truss

2. monocoque

Truss construction fuselages

use steel or aluminum tubing in a series of triangular shapes (called trusses) to get the necessary strength and rigidity

monocoque designs

use bulkheads, stringers, (running the length of the fuselage) and formers (perpendicular to stringers) of various sizes and shapes to support a stretched or "stressed" skin

wings

airfoils attached to each side of the fuselage that serve as the main lifting surfaces supporting the airplane in flight.

airfoil

an aircraft part or surface (such as wing, propeller blade, or rudder) that controls lift, direction, stability, thrust, or propulsion for the aircraft.

monoplanes

airplanes with one set of wings

biplanes

airplanes with two sets of wings

cantilever wing

requires no external bracing, getting its support from internal wing spars, ribs, and stringers, as well as the construction of the wing's skin or covering

semi-cantilever wing

requires both internal bracing and external support from struts attached to the fuselage

ailerons

extend from about the middle of the wing out toward the wingtip; they move in opposite directions to create aerodynamic forces that cause the airplane to roll

flaps

extend outward from near where the wing joins the fuselage (called the wing root) to about the middle of the wing's trailing edge. The flaps are usually flush with the rest of the wing surface when cruising flight; when they are extended, the flaps move downward together to increase the lift of the wing for takeoffs and landings. Most common high lift devices.

chord line

the distance from the leading edge of the wing to the trailing edge. Cuts the airfoil into an upper surface and a lower surface

mean camber line

if we plot the points that lie halfway between the upper and lower surfaces, we obtain a curve called the mean camber line.

camber

the maximum difference between the the mean camber line and the chord line. A measure of the curvature of the airfoil.

thickness

the maximum difference between the upper and lower surfaces

wingtips

the ends of the wings

wingspan

the distance from one wingtip to the other

a planform

the shape of the wing viewed from above

dihedral angle

when the left and right wings aren't truly horizontal to the fuselage, but instead meet at this angle. Built into the design for roll stability; a wing with some dihedral will naturally return to its original position if it encounters a slight displacement

Three basic wing types on modern airplanes

1. straight

2. Sweep

3. Delta

Straight wings

mostly found on small, low-speed airplanes, as well as gliders and sailplanes. These wings give the most efficient lift at low speeds, but are not very good for high speed flight, especially that approaching the speed of sound

swept wings

(either forward swept or swept back) is the most common design for modern high speed airplanes. Creates less drag than straight wing designs, but is somewhat more unstable at low speeds.

moderate sweep

commercial jetliner, resulting in less drag while maintaining stability at lower speeds

fighter planes have wings with...

a greater sweep, which do not generate much lift during low-speed flight and require relatively high speed take-offs and landings

delta wings

looks like a large triangle viewed from above. It has a high angle of sweep with a straight trailing edge. Airplanes with this type of wing design are designed to reach supersonic speeds, and also land at high speeds.

landing gear

provide the most support for the airplane when it is on the ground. Usually consists of three wheels or sets of wheels. Can be retractable or non-retractable.

retractable gear

can be mechanically pulled up into a cavity designed for them, with a door or doors closing over the opening to reduce drag and improve the airplane's performance

nonretractable landing gear

usually have fairings over their top half to reduce drag and improve the airplane's performance

conventional landing gear/tailwheel airplanes

landing gear using a tailwheel/ planes that have such landing gear

tricycle landing gear

designs with the third wheel under the nose (a nosewheel)

powerplant

in a propeller driven plane, usually considered to include both the engine and the propeller

engine

the primary function is to turn the propeller, but it also generates electrical power, provide a vacuum source for some flight instruments, and provides a heat source for pilot and passengers in most small single-engine planes.

fixed-pitch propeller

pitch has a blade angle that can't be changes by the pilot. The propeller is connected directly to the engine's crankshaft; engine power rotates the crankshaft as well as the propeller, and the propeller converts the engine's rotary power into thrust

variable pitch propeller (constant-speed propeller)

more efficient because the pilot can adjust the blade angle for most efficient operation

how jet engines work

forcing incoming air into a tube or cylinder where the air is compressed, mixed with fuel, burned, and pushed exhausted at high speed to generate thrust.

afterburner

a tube placed between the turbine and the rear exhaust nozzle where additional fuel is added to the flow and ignited to provide increased thrust. They greatly increase fuel comsumption, so they can only be used for short periods

tail assembly/empennage

includes the entire tail section, which consists of both fixed and movable control surfaces. The fixed surfaces are the vertical and horizontal stabilizers, and the movable surfaces include the elevators, the rudder, and any trim tabs

elevators

movable control surfaces attached to the back or the trailing edge of the horizontal stabilizers; they are used to move the nose of the airplane up or down during flight.

rudder

a movable control surface attached to the back of the vertical stabilizer that is used to move the airplane's nose left and right during flight. Used in combination with the ailerons for turns while the airplane is flying. Controls the airplane's movement around its vertical axis, or yaw.

trim tabs

small movable segments of the trailing edge of the rudder, elevators, and ailerons. Controlled by the pilot in the cockpit, they reduce control pressures and decrease the pilot's workload.

Newton's First Law of Motion (or inertia)

maintains that a body at rest ends to remain at rest, and a body in motion tends to remain in motion (at the same speed and in the same direction) unless it acted upon by an outside force. Nothing in nature starts or stops moving until some outside force causes it to do so.

Inertia

the property by which an object resists being accelerated in some different way from its current state

Newton's Second Law of Motion

the equation F=ma, where F is the force acted upon an object, m stands for an objects mass, and a is the object's acceleration. When an object is acted upon by a force, its resulting acceleration is directly proportional to the applied force and inversely proportional to the mass of the object. Force must be applied to overcome the inertia of an object: The greater the mass of an object, the greater the force needed to produce a particular acceleration.

Newton's Third Law of Motion

For every action there is an equal and opposite reaction. When one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object

Universal gravitation

Newton. Says that two objects attract each other with a force that is proportional to the product of their masses, and inversely proportional to the square of the distance between them. This attraction is commonly known as gravity.

gravity

accounts for the weight of an object on earth, and usually measures the pull of the large body (in this case, the Earth) in pounds or kilograms

mass

a constant that is unaffected by local gravitational conditions

weight

a function of the planet's gravity at that point. Can vary depending on where you are (ex: earth, the moon, outer space)

Four forces that act upon an aircraft in flight

1. Lift

2. Weight (or gravity)

3. Thrust

4. Drag

Lift

pushes the aircraft up (ie away from the earth;s surface)

weight (as a force acting on an aircraft in flight)

pulls the aircraft down toward the earth (or, more precisely, toward the Earth's center)

thrust

pushes the aircraft forward

drag

tends to slow the aircraft, pushing back on it as it moves forward

the flight envelope

consists of the different combinations of these factors (lift, weight, thrust, and drag) and others that allow the aircraft to be flown safely.

Bernoulli's Principle

as the velocity of a fluid increases, the pressure exerted by that fluid decreases. The faster a fluid (the air is a fluid, not a liquid) travels over a surface, the less time it has to exert pressure on any given part of that surface

stall

caused by the separation of airflow from the wing's upper surface, resulting in a rapid decrease in lift--possibly to the extent of falling out of the sky

weight (as a force)

the force produced by the mass of the airplane interacting with Earth's gravitational field; it is the force that must be counteracted by lift to maintain flight.

basic weight

the weight of the basic aircraft plus weapons, unusable fuel, oil, ballast, survival kits, oxygen, and any other internal or external equipment on board the aircraft that will not be disposed of during flight

operating weight

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 included in basic weight

gross weight

the total weight of an aircraft, including its contents and externally mounted items, at any time.

landing gross weight

the weight of the aircraft, its contents, and external items when the aircraft lands

zero fuel weight (ZFW)

the weight of the aircraft without any usable fuel

profile drag (parasitic drag)

experienced by all objects in an airflow, caused by the airplane moving the air out of the way as it moves forward

induced drag

the result of the production of lift. It is the part of the force produced 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.

flight attitude

whenever an airplane changes its position in flight

longitudinal axis

the axis that runs lengthwise through the fuselage from the nose to the tail. Movement around the airplane's longitudinal axis is called roll.

lateral axis

the axis that runs from wingtip to wingtip. Movement around the airplane's lateral axis is called pitch.

vertical axis

the axis that passes vertically through the aircraft's center of gravity. Movement around the airplane's vertical axis is called yaw--a horizontal (left and right) movement of the airplane's nose.

What are the three motions of the airplane's controlled by?

Roll is controlled by ailerons, pitch is controlled by the elevators, and yaw is controlled by the rudder.

What is the atmosphere composed of?

78 percent nitrogen, 21 percent oxygen, and 1 percent other gaseous elements such as argon and helium.

the atmosphere

the air surrounding the earth. It has mass and weight.

A flight control system has two ends:

the ends where the pilot makes a change to a control in the cockpit and the end where something on the outside of the aircraft changes and affects the airplane's performance (faster, slower, up, down, left, right, etc)

primary control systems

those needed to safely control an airplane during flight, including the ailerons, elevator/stabilator, and rudder

secondary control system

Improve the airplane's performance or relieve the pilot of having to deal with excessive control forces (ie wing flaps and trim control systems)

Ways to control the aircraft while in flight in the cockpit

1. the joystick or control wheel

2. the rudder pedals

3. the throttle(s) for the engine(s)

joystick

control roll and pitch

two rudder pedals

control the yaw of the airplane

engine throttles

the main way for the pilot to regulate how much thrust the engine is producing

ailerons

control the airplane's movement around the longitudinal axis, also known as roll. They are attached to the outboard trailing edge of each wing and move in opposite directions from each other

elevator

hinged control surface attached to the rear of the horizontal stabilizer. Controls the airplanes movement around its lateral axis, called pitch

leading edge devices

high lift devices can also be applied to the leading edge of the airfoil. the most common types are fixed slats, movable slats, and leading edge flaps

spoilers

high drag devices used on some airplanes that are deployed form the wings to spoil the smooth airflow, reducing lift and increasing drag.

trim systems

used to relieve the pilot of the need to maintain constant pressure on the flight controls.They aerodynamically assist movement and positioning of the flight control surface to which they are attached.

flight instruments

enable a pilot to operate an airplane with optimal performance and increased safety, especially when flying long distances or in inclement weather conditions

altimeter

measures height above a particular air pressure level, and therefore gives the pilot information about his altitude above the ground. Air is denser at sea level than at higher altitudes, so as altitude increases, atmospheric pressure decreases.

pressure altimeter

an anaeroid barometer that measures atmospheric pressure at the level where the altimeter is located, and presents an altitude in feet

the dial of a typical altimeter

is graduated, with numerals arranged clockwise form 0 to 9. The shortest hand indicated altitude at tens of thousands of feet, the intermediate hand in thousands of feet, and the longest hand in hundreds of feet.

standard sea level barometric pressure

29.92 inches of mercury

standard sea level free air temperature

+15 degrees Celsius or 59 degrees Fahrenheit

altitude

the vertical distance between some above point or level used as a reference.

indicated altitude

the uncorrected altitude read directly from the altimeter when it is set to the current altimeter setting

true altitude

the vertical distance of the airplane above sea level; the actual altitude. It is often expressed as feet above mean sea level (MSL); airport, terrain and obstacle elevations on aeronautical charts are true altitudes

absolute altitude

the vertical distance of an airplane above the terrain, or above ground level

pressure altitude

the altitude indicated when the altimeter setting window (barometric scale) is adjusted to 29.92. This is the altitude above the standard datum plane, which is a theoretical level where air pressure (corrected to 15 degrees Celsius) equals 29.92 inches of mercury (Hg). Pressure altitude is used to compute density altitude, true altitude, true airspeed, and other performance data.

density altitude

this altitude is pressure altitude corrected for variations from standard temperature. When conditions are standard, pressure altitude and density altitude are the same. If the temperature is above standard, the density altitude is higher than pressure altitude. If the temperature is below standard, the density altitude is lower than pressure altitude. This is an important altitude because it is directly related to the airplane's performance.

vertical speed indicator (VSI)

indicates whether the airplane is climbing, descending, or in level flight. The rate of climb or descent is indicated in feet per minute. Displays trend information that shows an immediate indication of an increase or decrease in the airplane's rate of climb or descent and rate information that shows a stabilized rate of change in altitude.

lag

the time from the initial change in the rate of climb until the VSI displays an accurate indication of the new rate.