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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Streamline, Streakline and Pathline

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Streamline

Streamlines are the ones that drawn such that their tangents at every point along the streamline are in the same directions as the velocity vectors at that point and forms a powerful tool in understanding flows. This definition leads to the equation of streamline as follows :


Streakline

A line created by particles in a flow that have previously passed through a common point in the flow field. It is obtained by a simple and efficient integration of particle pathlines within the flow solver as the unsteady flowfield is computed.  


Pathline

The line traced by a given particle when it flows from one point to another in a flow field. In unsteady flow, the pathlines for different fluid elements passing through same point are not the same. 



                                        











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Wing Twist

-
Image
  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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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 but drawin
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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 digit in tenths of chord giv
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