Wing

Airfoil selection Aerodynamic characteristics (Kmax, CLmax, stall characteristics) Structural reasons;

1

Airfoil geometry

Airfoil geometryCamber line Leading edge Chord Maximum thickness

Trailing edge Maximum thickness position Maximum camber Maximum camber position

2

Angle of attack definition

V

AoA

StallAoA=0 Separation point

AoA=10

AoA=15

AoA=20

3

Airfoil aerodynamic characteristicsLift coefficient (Cz or CL)C L MAXStall

Drag coefficient (Cx or CD )

dC l /d a0

KR

Airfoil aerodynamic characteristics

Design Cz

4

Airfoil aerodynamic characteristicsGliding ratio (Cz / Cx) Power factor (Cz3 / Cx2 lub Cz1,5 /Cx)

Airfoil aerodynamic characteristicsPitching moment coefficient Cm Derivative dCm/dCz is an indicator of stability. It is negative for stable aeroplanes and positive for unstable aeroplanes.

5

Maximum thickness t/cMaximum thickness - t

Chord - c

Effect of airfoil thickness on lift coefficient6% 8% 10% 12% 14% 16%

18%

20%

6

Effect of airfoil thickness on lift coefficient

Effect of airfoil thickness on drag coefficient6% 8% 10% 12% 14% 16%

18%

20%

7

Effect of airfoil thickness on gliding ratio6% 8% 10% 12% 14% 16%

18%

20%

Effect of airfoil thickness on power factor6% 8% 10% 12% 14% 16%

18%

20%

8

CamberCamber line

Maximum camber

Effect of airfoil camber on lift coefficient0%

0,5% 1% 1,5% 2%

2,5%

3% 3,5%

9

Effect of airfoil camber on drag coefficient0%

0,5% 1% 1,5% 2%

2,5%

3% 3,5%

Effect of airfoil camber on gliding ratio0%

0,5% 1% 1,5% 2%

2,5%

3% 3,5%

10

Effect of airfoil camber on power factor0%

0,5% 1% 1,5% 2%

2,5%

3% 3,5%

Effect of airfoil camber on moment coefficient0%

0,5% 1% 1,5% 2%

2,5%

3% 3,5%

11

Position of maximum thicknessMaximum thickness

Position of maximum thickness

Boundary layer developmentlaminar turbulent separated

transition separation

12

Effect of airfoil laminarity on drag coefficient15%

20%

25%

30% 35%

40% 45%

50%

Effect of airfoil laminarity on lift coefficient15%

20%

25%

30% 35%

40% 45%

50%

13

Effect of camber line shape on moment coefficient35% 0

2 4

6

28%

22%

15%

Effect of camber line shape on gliding ratio35% 0%

2% 4%

6%

28%

22%

15%

14

Reynolds number effect on aerodynamic coefficients

Effect of Mach number on lift coefficient

15

Effect of Mach number on drag coefficient

Effect of Mach number on moment coefficient

16

Critical Mach number

Historical values of an aeroplane airfoil thickness as a function of Mach number

17

Critical Mach number

Critical Mach number

18

Calculate Reynolds number for design airspeed

Airfoil selection500 000>Re Selig catalogue Summary of low speed airfoil data Vol.1-3 Airfoils at low speeds

Re>3 000 000 Calculate Mach number for maximum airspeed

3 000 000>Re>500 000 Wortmann catalogue Stuttgarter Profilkatalog Vol.1 i 2

Mmax>0,75

Mmax