16. Basic aerodynamic theory (Drag)

Question 1

Drag (opposes / enhances) motion through the air.

Answer 1

Opposes

Question 2

The force used to overcome the drag in straight and level flight is the …….. produced by the engine/propeller combination

Answer 2

Thrust

Question 3

If drag can be kept low, then …….. can be kept low

Answer 3

Thrust

Question 4

Total drag is the sum total of the various drag forces acting on the aeroplane, which act (parallel / perpendicular to) and (in the same direction as / opposite to) the direction of flight.

Answer 4

Parallel to; opposite to

Question 5

Total drag can be considered in two basic groups: drag that comes about in the generation of lift, known as …….. drag, and drag that is NOT associated with the production of lift, known as …….. drag.

Answer 5

Induced; parasite

Question 6

Parasite drag consists of ……..-…….., …….. …….. and …….. ……..

Answer 6

Skin-friction; form drag; interference drag

Question 7

Streamlining of shapes reduces …….. ……..

Answer 7

Form drag

Question 8

The additional turbulence caused by interference between various air flows around the aeroplane is called …….. ……..

Answer 8

Interference drag

Question 9

As the aeroplane flies faster, parasite drag (increase / decreases)

Answer 9

Increases

Question 10

The drag produced as a by-product in the generation of lift is called……..

Answer 10

Induced drag

Question 11

For a wing to produce an upward lift, the static pressure on the upper surface must be (higher / lower) than on the lower surface.

Answer 11

Lower

Question 12

Air flows around the wingtips from the higher pressure area on the (upper / lower) surface of the wing into the area of lower pressure. This forms wingtip ……..

Answer 12

Lower; vortices

Question 13

The formation of wingtip vortices and induced drag is greatest at (high / low) angles of attack.

Answer 13

High

Question 14

High angles of attack are associated with (high/ low) air speeds in straight and level flight.

Answer 14

Low

Question 15

Induced drag is highest at high angles of attack and (high / low) air speeds in straight and level flight

Answer 15

Low

Question 16

Induced drag increases at (high / low) airspeeds

Answer 16

Low

Question 17

Parasite drag increases at (high / low) speeds

Answer 17

High

Question 18

The total drag is at a minimum at (high speed / low speed / at a speed where the parasite drag and induced drag are equal)

Answer 18

At a speed where the parasite drag and induced drag are equal

Question 19

At the minimum total drag speed, the propeller has only to provide minimum ……..

Answer 19

Thrust

Question 20

At low airspeeds and high angles of attack, because of the greater …….. drag, the thrust must be (greater / less)

Answer 20

Induced; greater

Question 21

At high airspeeds and low angles of attack, because of the greater …….. drag, the thrust requirement is (greater / less)

Answer 21

Parasite; greater

Question 22

In the normal flight range, an increased airflow over an airfoil at the same angle of attack will cause (more / less / the same) lift and (more / less / the same) drag

Answer 22

More; more

Question 23

In the normal flight range, increasing angle of attack at a constant airspeed will cause (more / less / the same) lift and (more / less / the same) drag

Answer 23

More; more