POF Q31 - Propellers

Question 1

Constant-speed propellers provide a better performance than fixed-pitch propellers because they:

a.have a higher maximum efficiency than a fixed-pitch propeller.

b.produce an almost maximum efficiency over a wider speed range.

c.have more blade surface area than a fixed-pitch propeller.

d.produce a greater maximum thrust than a fixed-pitch propeller.

Answer 1

b.produce an almost maximum efficiency over a wider speed range.

Question 2

If you push forward the RPM lever of a constant speed propeller during a glide with idle power and constant airspeed, the propeller pitch will:

a.increase and the rate of descent will decrease.

b.decrease and the rate of descent will increase.

c.decrease and the rate of descent will decrease.

d.increase and the rate of descent will increase.

Answer 2

b.decrease and the rate of descent will increase.

Question 3

Which of the following statements about a constant speed propeller is correct?

a.The RPM decreases with increasing aeroplane speed

b.The blade angle increases with increasing aeroplane speed

c.The selected RPM is kept constant by the manifold pressure

d.The propeller system keeps the aeroplane speed constant

Answer 3

b.The blade angle increases with increasing aeroplane speed

Question 4

Which statement about propeller noise is correct?

1) Propeller noise remains the same when the blade tip speed increases.
2) For a given engine and propeller blade shape, a decrease in the number of propeller blades allows for a reduction in propeller noise.

a.1) is correct, 2) is incorrect.

b.1) is incorrect, 2) is correct.

c.1) is correct, 2) is correct.

d.1) is incorrect, 2) is incorrect.

Answer 4

d.1) is incorrect, 2) is incorrect.

Question 5

The blade angle is defined as the angle between:

a.The chord line and the Relative Airflow

b.The plane of rotation and the Relative Airflow

c.The plane of rotation and the chord line

d.The axis of rotation and the chord line

Answer 5

c.The plane of rotation and the chord line

Question 6

The helix angle is defined at the angle between:

a.The Relative Airflow and the plane of rotation.

b.The plane of rotation and the chord line

c.The axis of rotation and the plane of rotation

d.The chord line and the Relative airflow

Answer 6

a.The Relative Airflow and the plane of rotation.

Question 7

The distance a propellor would travel forward in one revolution at zero angle of attack is known as the

a.Geometric Pitch

b.Effective Pitch

c.Theoretical Pitch

d.Fine Pitch

Answer 7

a.Geometric Pitch

Question 8

The pitch of a propeller determines how far it moves through the air in one revolution. Over a set distance a propeller with a [ ] pitch will complete more revolutions than a [ ]pitch.

Answer 8

[fine] [course]

Question 9

A blade angle that can be adjusted mechanically on the ground (after manufacture), providing a singular blade angle in flight is known as…

a.Two Pitch

b.Fixed Pitch

c.Constant Speed

d.Adjustable pitch

Answer 9

d.Adjustable pitch

Question 10

The propulsion stream tube defines the volume in which most of the work is done by the propeller disc on the air. In the propulsion stream tube…

a.the total energy of the airflow remains constant

b.the total energy of the airflow decreases

c.the total energy of the airflow fluctuates

d.the total energy of the airflow increases

Answer 10

d.the total energy of the airflow increases

Question 11

With a variable pitch propeller, when you initiate a climb without touching the engine controls, TAS will decrease, this will cause the Blade angle and AoA to reduce.

Select one:
True
False

Answer 11

False

Question 12

The direction of the RAF to the propeller blade relies upon which two factors?

a.RPM

b.Angle of attack

c.Torque Drag

d.TAS

Answer 12

a.RPM

d.TAS

Question 13

For a fixed-pitch propeller, as aircraft speed is increased..

a… the RPM reduces

b… the blade angle of attack increases

c… the blade angle of attack reduces

d… the blade angle of attack remains constant

Answer 13

c… the blade angle of attack reduces

Question 14

Consider an aircraft with a fixed blade pitch angle. The blade has been rigged with a coarse blade angle.

a.The aircraft will be efficient at all speeds

b.The aircraft will be efficient during circuit flying, however, need a long take off run due to the sideways forces being produced by the propeller

c.The aircraft will be efficient during take off and inefficient during high speed flight

d.The aircraft will be efficient in the cruise at higher speeds but will require a long take off run

Answer 14

d.The aircraft will be efficient in the cruise at higher speeds but will require a long take off run

Question 15

A negative angle of attack results in a backwards total reaction.

Select one:
True
False

Answer 15

True

Question 16

Why do designers incorporate blade twist into propellers?

a.to provide a varying angle of attack along the blade, with the optimal angle of attack at 25% chord.

b.to provide a constant angle of attack along the length of the propeller

c.To prevents over stressing this propeller hub

d.To create a high angle of attack at the blade tip

Answer 16

b.to provide a constant angle of attack along the length of the propeller

Question 17

What is the working principle of a constant speed propeller?

a.The blade pitch angle is mechanically changed by a governor to keep a constant RPM by changing the angle of attack.

b.The blade pitch angle is mechanically changed through a pitch lever to keep a constant angle of attack by maintaining constant the selected RPM.

c.The blade pitch angle is mechanically changed through a pitch lever to keep a constant RPM by maintaining the TAS

d.The blade pitch angle is mechanically changed by a governor to maintain the optimal angle of attack by maintaining constant the selected RPM.

Answer 17

d.The blade pitch angle is mechanically changed by a governor to maintain the optimal angle of attack by maintaining constant the selected RPM.

Question 18

If an engine fails with a constant speed propeller, the blade will fine off.

Select one:
True
False

Answer 18

True

Question 19

A variable pitch propeller [ ]. A [ ] propeller will fine the propeller in the event of an engine failure. If there is an engine failure it is desirable for the propeller to [ ].

Answer 19

[maintains optimum efficiency over a range of speeds] [constant speed] [feather]

Question 20

Which of the following 4 images depicts a propeller blade in windmilling flight?

a.3

b.1

c.2

d.4

Answer 20

a.3