Coefficient of Lift

 

                                                                  Lift Coefficient:

Coefficient of lift C_L is defined as the lifting ability of the wing which depends on geometry of the airfoil. Coefficient of Lift Changes with change in angle of attack and it differs for symmetric and Assymetric airfoils.

To Know about Coefficient of lift C_L we plot the variation of lift with change in angle of attack.

For asymmetric airfoil at 0 degree of angle of attack the lift generated is minimum and at 15-16 degrees its maximum which is called C_{L max}. Angle of attack remains a straight line between 0 -12 Degrees. Above 12 Degrees rate of increase in lift reduces and forms a peak. The Peak formed denotes the maximum Angle Of attack C_{L max}. At angles of attack beyond this point Coefficient of lift C_L decreases which tends to reduce the lift.

 Now the Airfoil is stalled and it cannot produce further lift to maintain steady straight and levelled flight. The Angle at which C_{L max} occurs is called stalling angle of attack of the Airfoil.

The normal range of the Airfoil is between 0 Deg angle of attack and stalling angle of attack.

For symmetric airfoils at 0 degrees of angle of attack there is no lift. Each airfoils possess its own lifting Characteristics, so it’s possible to compare Assymetrical and Symmetrical Airfoils.

Assymetrical Airfoils generate lift at low angle of attacks and produce stall at low angle of attacks than a symmetrical Airfoil.