Aerofoila

Aerofoil Shapes plays a major role in understanding the principles of flight. This ppt gives basic knowledge about the aerofoil shapes and the variation of aerodynamic forces.

1. Principles of Flight Topic: Aerofoils

2. Aerofoils Cross sectional shape of an object that when moved through a fluid such as air, creates aerodynamic force. Aerofoils are employed as wings to produce lift, or in propeller blade to produce thrust. Other aerofoil surfaces includes tailplanes , fins, winglets, and helicopter rotor blades. Control surfaces (e.g. ailerons, elevators and rudders) are shaped to contribute to the overall aerofoil section of the wing or empennage

3. Definitions Leading Edge  = Forward edge of the aerofoil Trailing Edge  = Aft edge of the aerofoil Chord  = Line connecting the leading and trailing edge. Denotes the length of the aerofoil Mean Camber Line  = Line drawn half way between the upper and lower surface of the aerofoil. Denotes the amount of curvature of the wing Point of Maximum Thickness  = Thickest part of the wing expressed as a percentage of the chord

4. Types of airfoils (informal) Low cambered Deep cambered Symmetrical

5. Low cambered, flat bottomed: low drag high speed thin wing section suitable for race planes, fighters, interceptors, etc

6. Deep camber, flat bottomed: high lift low speed thick wing section suitable for transports, bombers

7. Deep cambered: high lift low speed thin wing section suitable for transports, bombers

8. Deep camber: low lift high drag reflex trailing edge wing section high stability

9. Symmetrical: (cambered top and bottom) low lift high drag high stability

10. High lift less drag lower weight good stall characteristics

11. NACA aerofoils  Airfoils described as NACA xxxx or NACA xxxxx or NACA xx y -xxx series.

12. The NACA 4-digit airfoils mean the following: The first digit expresses the camber in percent chord, the second digit gives the location of the maximum camber point in tenths of chord, and the last two digits give the thickness in percent chord. Thus 4412 has a maximum camber of 4% of chord located at 40% chord back from the leading edge and is 12% thick, while 0006 is a symmetrical section of 6% thickness.

13. The NACA 5 digit series airfoil means the following:  The first digit designates the approximate camber in percent chord, the second digit indicates twice the position of the maximum camber in tenths chord, the third (either 0 or 1) distinguishes the type of mean-camber line, and the last two digits give the thickness in percent chord. Thus, the 23012 airfoil has a maximum camber of about 2% of the chord located at 15% of the chord from the leading edge (3 tenths divided by 2) and is 12% thick.

14. The NACA six, seven and even eight series were designed to highlight some aerodynamic characteristic.  For example, NACA 65 3 -421 is a 6-series airfoil for which the minimum pressure's position in tenths chord is indicated by the second digit (here, at the 50% chord location), the subscript 3 means that the drag coefficient is near its minimum value over a range of lift coefficients of 0.3 above and below the design lift coefficient, the next digit indicates the lift coefficient in tenths (here, 0.4) and the last two digits give the maximum thickness in percent chord (here, 21% of chord).

15. Presentation by Musica.S.R, Assistant Professor, Dept. of Aerospace Engineering, Karunya University The END