AER3: Drag

Question 1

Define Drag

Answer 1

Force acting parallel and opposite to the direction of flight

Question 2

Two categories of drag?

Answer 2

Zero Lift Drag

Lift Dependent drag (Vortex drag + increments)

Question 3

What makes up zero-lift drag?

Answer 3

Surface friction drag
Form drag
Interference drag

Question 4

What does ZLD do with increasing speed

Answer 4

ZLD increases

Question 5

What does induced drag do with increasing speed

Answer 5

LDD decreases

Question 6

How does vortex drag get created?

Answer 6

The pressure differential induces a spanwise flow which creates vortexes at wingtips

Question 7

What is downwash?

Answer 7

Downwash is the air that is deflected by flowing around an airfoil.

Question 8

What factors affect induced drag?

Answer 8

a. Planform.
b. Aspect Ratio.
c. Lift and Weight.
d. Speed.

Question 9

What features/devices can reduce induced drag?

Answer 9

a. Winglets.
b. Aspect Ratio.
c. Wing Taper.
d. Washout.
e. Tip Tanks/Missiles.

Question 10

What is Vimd?

Answer 10

Indicated Minimum Drag
VIMD is the speed at which total drag is lowest. It
coincides with the best lift/drag ratio speed.

Question 11

What is V M eas/d?

Answer 11

Maximum EAS/drag ratio speed is the main
aerodynamic consideration for best range. It has the
value of 1.32 x VIMD.