Basic Anatomy of an Airplane
Before understanding how an aircraft flies, we need to know what are the basic parts of the aircraft. Also know the function of all these various parts will help us understand what are they capable of doing when the aircraft is airborne.
The basic parts of an airplane (source: theatlasgroup)
Main parts of the aircraft which make up the airframe, which is the complete body of the aircraft excluding the engines are as follows:-
1) Fuselage - the main body of the aircraft responsible for holding the passengers/cargo in technical terms called as payload. Its a streamlined shape to reduce air resistance as much as possible.
2) Wings - the main lift producing surface of an aircraft, which is responsible for lifting the aircraft from the ground. It is also responsible for holding fuel, and various other controls/indications.
3) Tail section - comprising of horizontal and vertical tail responsible for stabilizing the plane and controlling the vertical and horizontal movements of the aircraft.
Basic Terms to keep in mind -
1) Aerofoil/Airfoil - The smooth and streamlined shape responsible to produce maximum amount of lift with least amount of drag. The fuselage, wings, tail etc. all use this shape.
2) Trailing and Leading Edge - the rear section wing/tail is called trailing edge and the front section of wing/tail is called leading edge.
3) Port and Starboard - The left side of the aircraft with reference to captain/pilot is called port and right side of the aircraft with reference to captain/pilot is called starboard.
4) Wing Root and Tip - The part of the wing connected to the fuselage is called as the root of the wing which is the largest section of the wing and the part of the wing far away from the fuselage is called as the tip of the wing which is the smallest section of the wing
5) Engine Numbers - All measurements for the aircraft are made in reference with the captain. The left of the captain or the port side the engines are numbered from left to right. So if its a twin engined aircraft, engine on left wing is engine number 1 and engine on right wing engine number 2. Similarly for four engined aircraft, the engines on the left wing starting from the tip of the wing is 1 and 2 and right wing starting from the root is 3 and 4.
The aircraft is controlled using various set of controls. Some of them directly and some of them indirectly. They are classified into two main categories.
1) Primary Control Surfaces
2) Secondary/Auxiliary Control Surfaces
Primary Control Surfaces
These are the main control surface responsible for the basic motions of the aircraft. Hence they are the primary control surfaces, controlling the primary motions. These control surfaces are:-
1) Ailerons - located on the trailing edge of the wings, responsible for rolling motion of the aircraft.
2) Elevators - located on the trailing edge of the horizontal tail, responsible for pitching motion.
3) Rudders - located on the trailing edge of vertical tail, responsible for the yawing motion.
Secondary Control Surfaces
These are the control surface which produce secondary effect to the flying control surfaces. They improve the performance characteristics of aircraft and reduce loads on pilot. These include various controls such as:-
1) Slats - located on leading edge of the wing used to improve lift, used during take off and landing.
2) Flap - located on leading/trailing edge of wing used to increase lift/drag, used during takeoff and landing
3) Spoilers - located closer to trailing edge of wing, used to spoil or destroy lift, used in flight and ground.
4) Trim tabs - located on trailing edge of various primary control surface, primarily used in flight to correct the movements and assists the pilot.
These are various terminologies used within the aviation industry.
1) Airfoil - The streamlines/aerodynamic shape that is responsible for producing lift when driven through air with least amount of air resistance.There are four main types of airfoil:-
a) Flat - Bottom airfoil - the top surface of the airfoil has a curvature called camber, the bottom surface is considerably flat
b) Symmetrical airfoil - both the top and bottom surface of airfoil has equal curvature.
c) Semi-symmetrical airfoil - top surface has a certain curvature but the bottom surface has much lower curvature.
2) Camber - the curvature of the airfoil is commonly called as the camber of the airfoil.
3) Chordline - the imaginary line passing through the center of the airfoil joining the leading and trailing edge of the airfoil
4) Relative airflow - the airflow experienced by the aircraft relative to its direction of motion is called relative airflow. It is always in opposite direction of flight path, which is the direction of travel of the aircraft.
6) Angle of attack - the angle created between the relative airflow and the chordline of the wings.
7) Centre of Pressure - The point on the chordline of an airfoil where the total lift of an airfoil is said to act. It could be located anywhere from 10% - 50% of the chordline from the leading edge.
8) Lift - the force acting upwards which is responsible for raising the aircraft from the ground.
9) Drag - the air resistance acting on the aircraft and its various parts of the aircraft.
10) Axes - The various reference lines about which an aircraft moves is called its axes. There are three main axes longitudinal (nose to tail of aircraft), lateral (wing tip to wing tip of aircraft), vertical/direction/normal (passing vertically upwards through an aircraft). All these axes pass through a point called center of gravity.
11) Center of gravity - it is point where the total weight of the aircraft is said to act. It is the main pivotal point of the aircraft around which all aircraft motions take place.
12) Angle of Incidence - it is the angle between the chordline of the wing and the longitudinal axis of the aircraft. It is fixed by the manufacturer, generally between 2 - 4 degrees.
13) Wings - they are the main lift producing surface of the aircraft. It is usually the fixed part and it also has movable parts called the ailerons. Wings are also called as mainplane.
14) Horizontal tail - they consist of fixed surface called horizontal stabilizer and movable surface called elevator. They stabilize the rear section of the aircraft horizontally. Horizontal tail are also called as tailplane.
15) Vertical tail - they consist of fixed surface called vertical stabilizer and movable surface called rudder. They stabilize the rear section of the aircraft vertically.
16) Wing inclinations - The aircraft wing could be inclined upwards or downwards depending upon their application or mission requirements. Based on these inclinations there are two basic designs:-
a) Wing Dihedral - The inclination of the wing upwards with respect to the lateral axis of the aircraft.
b) Wing Anhedral/Cathedral - The inclination of the wing downwards with respect to the lateral axis of the aircraft.
17) Wing twists - The passenger airliners wings are twisted from root of the wing to tip to better distribute air and loads acting on them. Also they help reduce the effects of unstable condition called stall. There are mainly two twist configurations, these are:-
a) Wash In - When the wing root is set at a lower angle of incidence than the wing tip. This causes the tip of the wing to stall first.
b) Wash Out - When the wing root is set at a higher angle of incidence than the wing tip. This causes the root of the wing to stall first.
18) Wing Shape - The shape of an aircraft wing in planform has a great influence on its aerodynamic
characteristics.
19) Wing Span - The straight-line distance measured from tip to tip.
21) Wind Loading - The weight per unit wing area.
22) Root Chord - The chord length at the centreline of the wing (the mid-point along the span).
23) Tip Chord - The chord length at the wing tip.
24) Tapered Wing - A wing in which the root chord is greater than the tip chord.
25) Taper Ratio - The ratio of tip chord to root chord usually expressed as a percentage.
26) Swept Wing - A wing in which the quarter chord line is not parallel with the lateral axis of the aircraft.
27) Sweep Angle - The angle between the quarter chord line and the lateral axis of the aircraft.
28) Mean Aerodynamic Chord - The chord line passing through the geometric centre of the plan area of the wing (ie. the centroid).
29) Indicated Airspeed (IAS) - The speed displayed on the airspeed indicator (ASI) is known as indicated airspeed. It does not include corrections for instrument errors and static pressure measurement errors (pressure error), both of which are very small. The indicated airspeed will differ progressively from actual flight speed as altitude increases and, consequently, density (ρ) decreases (q = ½ρV²). The notation for IAS is (VI).
30) Calibrated Airspeed (CAS) - Also known as Rectified Airspeed (RAS), this is the speed obtained by applying theappropriate instrument error and pressure error corrections to the ASI reading. The notation for CAS is (Vc).
31) Equivalent Airspeed (EAS) - The equation for IAS (dynamic pressure) is derived from Bernoulli’s equation, which assumes air to be incompressible. Below about 300 knots the compression that occurs when the airflow is brought to rest (as in the pitot tube) is negligible for most practical purposes, becoming increasingly significant above that speed. EAS is obtained by applying the compressibility correction to CAS. The notation for EAS is (Ve).
32) True Airspeed (TAS) - The true airspeed is the actual flight speed relative to the surrounding atmosphere, regardless of altitude. It must, therefore, take account of air density and is obtained by applying the formula:
where 
TAS is given the notation (V). At 40,000 ft, where standard density is one-quarter sea level
density, TAS will be twice EAS (√0.25 = 0.5). British ASI’s, in common with most others, are
calibrated for ISA mean sea level density (ρ0), where EAS = TAS. At all greater altitudes TAS will be greater than EAS by a proportional amount.
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