Propeller Theory

Question 1

The helix angle is defined as the?

Answer 1

angle between the relative airflow and the plane of rotation

Question 2

From the boss to the tip, a propeller pitch angle/blade angle -

and this is called?

Answer 2

decreases, helical twist

Question 3

The distance a propeller moves entirely due to the aircrafts forward speed, is called?

Answer 3

the advance per revolution

Question 4

The pitch angle, or blade angle, is defined as the -

Answer 4

angle between the chord line and the plane of rotation

Question 5

if a propeller blade is rotated at zero degrees angle of attack (i.e at the blade angle) for one revolution, it will theoretically advance a certain distance, this is called?

Answer 5

the geometric pitch

Question 6

The difference between geometric pitch and effective pitch is called?

Answer 6

Propeller slip

Question 7

As a propeller driven aircraft flies faster, due to the relative airflow the propeller angle of attack will?

Answer 7

decrease, because the relative airflow changes.

Question 8

At faster airspeeds, the propeller angle of attack should be -

Answer 8

Increased

Question 9

At faster airspeeds the propeller relative airflow will

Answer 9

change

Question 10

When RPM is selected on a variable pitch propeller, what component is being altered?

Answer 10

The speeder spring, which determines the amount of centrifugal force applied by the flyweights.

Question 11

If the propeller is stuck in the full coarse position, the likely cause is?

Answer 11

Broken speeder spring, causing the flyweights to allow oil to flow to the hub.

Question 12

The component that controls oil flow to the hub?

Answer 12

The flyweights

Question 13

If the pitch is stuck on full fine, the likely cause is?

Answer 13

Loss of oil pressure

Question 14

With a clockwise rotating propeller, torque effect will cause the aircraft to turn to the -

Answer 14

Left

Question 15

With a clockwise rotating propeller, slipstream effect will cause the aircraft to turn -

Answer 15

to the left

Question 16

The prop blade is twisted to -

and why -

Answer 16

maintain a constant angle of attack

Since, with a constant helix angle, the pitch angle increases closer to the tip.

Question 17

Between the helix angle and the pitch/blade angle, which can we alter with a constant airspeed?

Answer 17

The pitch/blade angle

Question 18

If we alter the pitch/blade angle, what will be the effect of the angle of attack?

Answer 18

It will decrease or increase

Question 19

Using only airspeed, which angle can we change?

1. Helix angle
2. The pitch/blade angle

Answer 19

The helix angle, since it’s related to the relative airflow.