Propellers

Question 1

What is the definition of propeller efficiency?

Answer 1

The ratio of thrust horsepower to brake horsepower.

Brake horsepower is the difference between the power a prop should theoretically be able to produce and what it actually produces because of factors like inefficiencies of combustion and internal friction,

Question 2

What is geometric pitch?

Answer 2

The theoretical distance a propeller should advance in one rotation if it was 100% effective.

Effective pitch is the distance it actually travels

Question 3

What is propeller slip?

Answer 3

The difference between geometric pitch and effective pitch

Question 4

What four ‘effects’ does a propeller produce on the airplane?

Answer 4

• Torque
• Slipstream
• Gyroscopic Precessions
  *Asymetric Thrust (P Factor)

Question 5

What direction does a prop rotate from the perspective of the pilot?

Answer 5

Clockwise

Question 6

What is slipstream and how is it countered?

Answer 6

For cruise flight engineres have offset the vertical fin a bit to compensate.

In low airspeed the offset fin isnt enough and you need to apply right rudder

Question 7

What is slipstream and how is it countered?

Answer 7

For cruise flight engineres have offset the vertical fin a bit to compensate.

In low airspeed the offset fin isnt enough and you need to apply right rudder

Question 8

What is gyropscopic effect?

Answer 8

Question 9

What is asymmetric thrust/p-factor?

Answer 9

Question 10

In a fixed pitch propeller, what controlls the RPM?

What controlls the RPM in a variable pitch prop?

Answer 10

Fixed: Throttle
Variable:

Question 11

What is the most advanced of the variable pitch props?

Answer 11

A constant speed system

Question 12

In a constant-speed prop how does it maintain the RPM you set?

Answer 12

It automatically changes the prop blade angles to maintain the RPM you set as power (throttle, airspeed) is changed