Lift and Drag

Question 1

The greater the C_L max:

a) The greater the stall speed
b) Stall speed remains constant, not related to C_L max;
c) The lower the stall speed

Answer 1

c) C_L max should be as high as possible as it reduces stall speed, and hence takeoff and landing speeds.

Question 2

Where does C_DMIN occur in a symmetrical aerofoil?

Answer 2

At 0º AoA.

Question 3

L/D ratio:

a) Varies with altitude/density;
b) Remains constant with changing altitude/density

Answer 3

b) The L/D ratio (also C_L/C_D ratio) remains constant and is independant of all other factors, it only varies with AoA.

Question 4

L/D ratio also indicates what for a wing?

Answer 4

The wings efficiency

Question 5

During cruise, best L/D occurs at?

a) V_IMP
b) V_IMD
c) V_NE
d) V_FE

Answer 5

b) V_IMD - Best Range

Question 6

C_L¹/C_D gives us:

a) Best Range
b) Best Endurance

Answer 6

a) Best range

Question 7

C_L^3/2/C_D gives us:

a) V_IMP
b) V_IMD
c) V_NO
d) V1

Answer 7

a) V_IMP = Best Endurance