BAK - Principles of Flight (Lift & Drag)

Question 1

At the same airspeed and without flaps deflected, will an increase in angle of attack increase or decrease the lift AND drag produced?

Answer 1

increase - lift AND drag

Question 2

Would a decrease in IAS (constant airspeed and AoA), increase or decrease the lift AND drag produced?

Answer 2

decrease - lift AND drag

Question 3

When flaps are lowered (flaps down) (constant airspeed and AoA), is the lift and drag of the aerofoil increased or decreased?

Answer 3

increase - lift AND drag

Question 4

What happens to the lift AND drag on an aerofoil if the AoA is increased gradually from a relatively low value (say 5deg) to the critical AoA/ stalling angle?

Answer 4

gradual increase in both lift AND drag up to the critical AoA/ stallling angle

loss of lift and significant drag beyond critical AoA/ stalling angle

Question 5

At a constant AoA and airspeed, what does lowering the flaps do to the camber of the aerofoil?

Answer 5

increase camber

Question 6

At a constant IAS and shape (flap setting), what effect does lowering the nose have on the lift and drag forces?

Answer 6

decrease both lift AND drag forces

Question 7

In straight and level flight at low IAS, will the AoA be relatively high or low, and at high IAS would the AoA be relatively high or low?

Answer 7

high AoA at low IAS (for straight and level flight)

low AoA and high IAS (for straight and level flight)

Question 8

Does the first half of flap deflection (down) produce a high or low increase in lift, and does it produce a high or low increase in drag?

Answer 8

relatively HIGH increase in LIFT

relatively LOW increase in DRAG

Question 9

What flaps are fully deflected (down), what force has the greatest increase - lift or drag?

Answer 9

drag

Question 10

What is the sum of the induced drag (from wings only) and the parasitic drag (from wings and fuselage) known as?

Answer 10

total drag

Question 11

What is another term for parasitic drag?

Answer 11

zero-lift drag

Question 12

As depicted on a total drag graph, at low airspeeds where the AoA is high, is induced drag (lift-dependent drag) high or low?

Answer 12

induced drag high at low airspeed and high AoA

Question 13

As depicted on the total drag graph, at low AoA and high airspeeds, which is higher between induced drag and parasitic drag?

Answer 13

parasitic drag

Question 14

What is the speed referred to on the total drag graph whereby the induced and parasitic drag intersect (total drag at its minimum value)?

Answer 14

minimum drag speed

Question 15

What type of drag results directly from the production of lift (the wings)

Answer 15

induced drag (lift-dependent drag)

Question 16

What is the approximate angle for the maximum lift/drag (L/D) ratio?

The same angle at which the IAS is at its maximum for the L/D ratio.

Answer 16

4 degrees (AoA of the aerofoil)

Question 17

The IAS for maximum lift/drag (L/D) ratio is the speed for minimum drag. Why is this airspeed important, what does it provide?

Answer 17

best glide speed (economical)

Question 18

Skin friction and form drag are the main components of which type of drag - induced or parasitic drag?

Answer 18

parasitic