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Wing Twist

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  Wing twist is of two types named as geometric twist and aerodynamic twist:- Geometric Twist Different angles of attack at wing root and tip. Wash in Tip chord has a higher angle of attack than that of root chord. Wash out Angle of attack at tip is lower than that at wing root. It is useful in reducing tip vortices. Aerodynamic Twist Difference between zero-lift lines of airfoils at wing root and near the tip. Airfoils at root and near the tip have different zero lift angles of attack.
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NACA Airfoil Nomenclature

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The NACA airfoils are airfoil shapes for aircraft wings designed by National Advisory Committee for Aeronautics (NACA). The shape of NACA airfoils is identified by a logical series of digits following the word NACA such as "NACA 2412" . Every digit there signifies the dimensional properties of that airfoil. NACA series extend upto 8-series but the most commonly used are defined by 4-digit, 5-digit and 6-digit series. NACA 4- Digit Series In the 4-digit series, every digit tells about the dimension of the airfoil as per the order:  1.  - First digit describes maximum camber in percentage of the chord length c = 0.02c  2.  - Second digit tells about the location of maximum camber in tenths of chord length c = 0.3c  3.  - Last two digits signifies the thickness of airfoil in percentage of chord length c = 0.16c  NACA 5- Digit Series It has an additional parameter to emphasize for the performance parameter i.e. Lift coefficient, Cl. 1.  - 3/2 of first...
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Aerodynamic Center

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  Aerodynamic Center The aerodynamic center is the point on the chord at which the pitching moment coefficient does not vary with lift coefficient, i.e. angle of attack. It is the point where the aerodynamic forces are supposed to act, a fixed location on the chord. Lift and drag forces can be applied at a single point, where they exert zero torque, at center of pressure but it moves with angle of attack as pressure distribution changes thus, makes the aerodynamic analysis complex. For most low speed airfoils aerodynamic center lies at (1/4) of chord back from the leading edge in supersonic airfoils it is nearer to the (1/2) chord location. In case of symmetric airfoils the aerodynamic moment about ac is zero for all angles of attack. With camber, the moment is non-zero and constant for thin airfoils. For a positive camber airfoil the moment is negative and results in the counter-clockwise rotation of the airfoil.
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NACA Airfoil Nomenclature

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Image
The NACA airfoils are airfoil shapes for aircraft wings designed by National Advisory Committee for Aeronautics (NACA). The shape of NACA airfoils is identified by a logical series of digits following the word NACA such as "NACA 2412" . Every digit there signifies the dimensional properties of that airfoil. NACA series extend upto 8-series but the most commonly used are defined by 4-digit, 5-digit and 6-digit series. NACA 4- Digit Series In the 4-digit series, every digit tells about the dimension of the airfoil as per the order:  1.  - First digit describes maximum camber in percentage of the chord length c = 0.02c  2.  - Second digit tells about the location of maximum camber in tenths of chord length c = 0.3c  3.  - Last two digits signifies the thickness of airfoil in percentage of chord length c = 0.16c  NACA 5- Digit Series It has an additional parameter to emphasize for the performance parameter i.e. Lift coefficient, Cl. 1.  - 3/2 of first...
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How to calculate Mean Aerodynamic Chord?

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Mean Aerodynamic Chord  The distance between leading and trailing edge of the wing, measured parallel to the normal airflow over the wing, is known as the chord. If the leading edge and trailing edge of the wing are parallel then, chord is constant along the span. Most commercial or fighter aircrafts have swept or delta wings in which chord length is greater at the root than at the tip. Consequently, chord changes along the span of the wing. The average length of Chord is known as Mean Aerodynamic Chord.  It has a geometrical importance as CG should be located at certain point of the MAC in percentage of its length. So, the location of MAC is specific and it can be found out as: Locating MAC Measure the root and tip chord and draw following points on plane : At the root of the wing, draw a line parallel to the fuselage centerline extending forward from leading edge and rearward from the trailing edge. Both lines should be the length of tip chord. Do the same thing at the tip b...
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Role of Camber in an Aerofoil

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Camber is defined as the convexity of the curvature of an Aerofoil from leading edge to the trailing edge. It is the fundamental component of Aerofoil design which varies with the volitional speed, strength and purpose of the Aerofoil. The Greater the camber of the center line (line equidistant from leading and trailing edge) the more convex will be the upper surface. When upper and lower surfaces are mirror images, that leads to the mean camber line to be coincident with chord line then, airfoil is called as uncambered airfoil or airfoil of zero camber.  Uncambered Airfoils are also known as Symmetric Airfoils as mean camber line coincides with the chord line. Camber creates a pressure difference between the upper and lower surfaces of the airfoil even at zero angle of attack, as air flows at a higher velocity on the upper surface compared to lower surface which creates a low pressure at upper surface and high pressure at lower surface, due to which there is a generation of lift ...
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