What is the chord line of an aerofoil?

The straight line joining the leading and trailing edges

The line midway between the upper and lower surfaces

The maximum distance between the upper and lower surfaces

How is the angle of attack defined?

Angle between the chord line and the direction of the undisturbed flow

Angle between the camber line and the chord line

Angle between the upper surface and lower surface

Angle between the span and the flow

How is the aspect ratio of a wing defined?

AR = b^2/S, span squared over plan area

AR = S/b^2, plan area over span squared

What happens at the stall angle?

The flow separates and the lift drops suddenly

2072 Chaitra · 2 marks

Terms associated with the aerofoil

Short answer

Chord line joins leading and trailing edges; chord length is the reference dimension. Camber is the maximum distance between the camber line and chord line. Angle of attack is the angle between chord line and freestream. Span is wing length perpendicular to flow. Stall angle is where lift suddenly drops.

Define the terms associated with the Aerofoil with neat sketch.

An aerofoil (airfoil) is a streamlined body shaped to produce lift with low drag when placed in a flow, as in wings and blades.

              chord line  c
      leading  <------------------------->  trailing
       edge    ___________________          edge
         (    /       camber line  \___
          \  /_________ mean line ______>
           \/___________________________/
   angle of attack a: between chord line and flow
 flow ->

Leading edge: the front, rounded edge of the aerofoil.
Trailing edge: the rear, sharp edge where the flow leaves.
Chord line: the straight line joining the leading and trailing edges.
Chord length ( $c$ ): the length of the chord line; it is the reference length for the Reynolds number.
Camber line (mean line): the line midway between the upper and lower surfaces. Camber is its maximum distance from the chord line.
Thickness: the maximum distance between upper and lower surfaces, usually given as a percentage of chord.
Angle of attack ( $\alpha$ ): the angle between the chord line and the direction of the undisturbed flow.
Span ( $b$ ): the length of the wing perpendicular to the flow.
Aspect ratio: $AR = b^2/S$ (span squared over plan area).
Stall angle: the angle of attack at which the flow separates and lift drops suddenly.

✓ Answer checked by Claude Opus 5.5 (high effort)

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