4.12 Discussion

4.12.1 Wing CL versus Angle of Attack, α

-10 -8 -6 -4 -2 0 2 4 6 8 100

0.05

0.1

0.15

0.2

0.25

0.3

Cl wing vs angle of attack

wing

Anle ogf attack,alpha

lft co

efficie

nt, C

l

Figure 4.1 Wing Coefficient of lift versus Angle of Attack, α

The graph above shows coefficient of lift for wing.. Graph show increment as the angle

of attack increase. The graph seems logical when compared with other reference graph.

-10 -5 0 5 10 15

-1

-0.5

0

0.5

1

1.5

Wing Coefficient Lift vs Angle of Attack

2Dexperiment

angle of attack

lift co

effici

ent

Figure 4.2 Wing Coefficient Lift vs Angle of Attack, α

The graph above show the combination of wing lift coefficient for 2D and experiment

versus angle of attack. The graph starts increase at 0º angle of attack. It is because angle of

attack is directly proportional to lift coefficient. Angle of attack increase, the lift coefficient also

increases. It has shown that lift coefficient dependent on angle of attack. For the experiment

graph, we get the value from UIUC database NACA 4412. In comparison to our data, it is shown

that our calculation almost the same with data from UIUC.

4.12.2 Various lift versus angle of attack

-10 -5 0 5 10 15

-1.5

-1

-0.5

0

0.5

1

1.5

Various Lift vs angle of attack

wingbodywing bodywing body tail

angle of attack,alpha

lift co

efficie

nt,C

l

Figure 4.3 Various of Lift versus Angle of attack

Figure 4.3 shows a relationship for different lift coefficient,CL (wing, body, wing-body

and wing-body-tail) various with angle of attack, α.

The graph indicates that the coefficient of lift for different condition have the same

behavior towards the changes of angle of attack. The coefficient of lift increases with the

increases of angle of attack, but when the airplane reaches the maximum angle of attack, αCLmax ,

the airplane will experience stall because the coefficient of lift CLwill start decrease after the

critical angle of attack.

In this case the maximum lift,CLmax=1.507 and the maximum angle of attack is αCLmax=¿

13.19º as referring to our wing lift calculation because it is the major contribution to the lift.

3.13.4 Various Drag versus Angle of Attack

Figure 3.7 Various Drag vs Angle of Attack

0 1 2 3 4 5 6 7 8 90

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Various drag vs angle of attack

wingbodywing bodywing body tail

Angle of attack, alpha

Drag

coeffi

cient

,Cd

This graph shows the various drag coefficients versus angle of attack. There are four

type of drag acting on the aircraft which are body drag, wing drag, wing body tail drag, and wing

body drag. In theory, coefficient of drag increases as the angle of attack increases. Increase angle

of attack will increases both lift and drag with lift increasing faster than drag up to a certain

critical angle. At and beyond the critical angle, drag increases enormously, lift drops to nearly

zero, and an aerodynamic stall occurs. Wing Body has the highest drag coefficient while wing

body tail has the lowest drag coefficient. Wing drag has high gradient compare to the body drag

graph. Wing body tail and wing body has almost similar in gradient of graph.

3.13.5 Drag Coefficient versus Lift Coefficient

0 0.2 0.4 0.6 0.8 1 1.2 1.40

1

2

3

4

5

6

7

8

Drag Coefficient vs Lift Coefficiet

wingwing bodywing body tail

Lift Coefficient

Drag

Coe

fficie

nt

Figure 3.8 Drag Coefficient vs Lift Coefficient

The graph above shows drag coefficient vs lift coefficient. Graph wing body tail shows

parabolic pattern while both wing body and wing shows almost in linear pattern. Basically the

Lift vs Drag curve shows where the wing/airplane provides the most amount of lift for the least

amount of drag, meaning the least amount of thrust, meaning the most economical speed. For

wing body tail, graph show higher amount of lift compare to the least amount of drag. Graph

wing body shows the negative slope for Cd vs CL graph. Therefore, a modification should be

made to minimize the drag effect and maximise the lift effect on the aircraft.