# Aerofoil

Aerofoil or airfoil refers to a cross-sectional shape whose design takes place with curved surface that provides the most favourable ratio between lift and drag in flight. Furthermore, lift is the component such that the force turns out to be perpendicular to the motion’s direction. In contrast, drag is the component that is parallel to the motion’s direction.

## Introduction to Aerofoil

The designing of the aerofoil is dependent on aerodynamic characteristics. Moreover, these aerodynamic characteristics depend on the speed, weight, and the purpose of the aircraft. Also, these depend on certain terms that must be defined in order to get a proper understanding of the design.

Aerofoil design happens to be a major facet in the field of aerodynamics. Moreover, various airfoils are helpful for different flight regimes. Most noteworthy, there is a generation of a lift at zero angle of attack by symmetric airfoils, while a symmetric airfoil is more appropriate for frequent inverted flight as in an aerobatic airplane.

Aerofoil

Chord refers to the distance between the leading edge, the point at the aerofoil’s front and has maximum curvature, and the trailing edge, the point at the aerofoil’s rear that has maximum curvature along the chord line. Moreover, the chord line refers to the straight line that connects the leading and trailing edge.

Upper surface, also known as suction surface, is one whose association takes place with high velocity and low static pressure. In contrast, the lower surface, also known as pressure surface, is one that is characterized by higher static pressure.

There are some terms that describe the behaviour when the movement of the aerofoil takes place through a fluid. Furthermore, the pitching moment is independent of lift coefficient and angle of attack (AOA) at the aerodynamic centre. Moreover, the pitching moment is zero at the centre of pressure.

The angle of attack (AOA) refers to an angle whose formation takes place between a reference line on a body and the oncoming flow. Furthermore, the pitching moment refers to a moment or torque that leads to the production of the aerodynamic force on the aerofoil.

### Types of Aerofoils

There are essentially two types of aerofoils- symmetrical and non-symmetrical. Symmetrical aerofoil has identical upper and lower surfaces such that the chord line and mean camber line happen to be the same, resulting in the production of no life at zero AOA. Moreover, this type has application in the main rotor blades of various light helicopters.

Non-symmetrical aerofoil, also known as cambered aerofoil, has different upper and lower surfaces such that the chord line happens to be placed above with large curvature. Furthermore, their chord line and chamber line are different. Also, the advantages of this type are a better lift to drag ratio and stall characteristics, thereby resulting in the production of a useful lift at zero AOA.

### Lift Coefficient

Lift coefficient, simply speaking, is a dimensionless coefficient that provides us the relationship between the lift, fluid velocity and the associated reference area. Furthermore, the generation of the lift takes place by lifting a body to fluid density. Moreover, the mathematical representation of lift coefficient is as follows:

$$C_{L} = \frac{L}{qS} = \frac{L}{\frac{1}{2}pu^{2}S} = \frac{2L}{pu^{2}S}$$

Where,

CL: lift coefficient

L: lift force

S: relevant surface

q: fluid dynamic pressure

⍴: fluid density

u: flow speed

## FAQs For Aerofoil

Question 1: What are the various types of aerofoil?

Answer 1: There are essentially two types of aerofoils- symmetrical and non-symmetrical. Symmetrical has identical upper and lower surfaces such that the chord line and mean camber line happen to be the same, resulting in the production of no life at zero AOA. Non-symmetrical, also known as cambered aerofoil, has different upper and lower surfaces such that the chord line happens to be placed above with large curvature.

Question 2: Explain what is meant by aerofoil?

Answer 2: An aerofoil refers to the cross-sectional shape of a wing, blade (of a turbine, propeller, or rotor), or sail. Furthermore, a body of such a shape moving through a fluid will cause the production of an aerodynamic force.

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