Fixed and Composite Propellers Quiz

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Questions and Answers

What is the primary benefit of anodising aluminium alloy blades in propellers?

Enhances corrosion resistance (correct)
Improves fuel efficiency
Increases thrust
Reduces weight

What is a key characteristic of steel propellers that makes them susceptible to issues without treatment?

Corrosion resistance
High malleability
Brittleness (correct)
Low weight

Which process specifically distributes stresses evenly in the surface of metal propellers?

Shot peening (correct)
Metal casting
Electroplating
Anodising

Which type of materials are typically employed in shot peening processes?

Steel and glass beads (D) Signup and view all the answers

Which characteristic is NOT a result of anodising aluminium alloy propeller blades?

Increased strength (D) Signup and view all the answers

What is the purpose of using a go-no-go gauge during the inspection of the wear?

To check for proper fit and alignment. (C) Signup and view all the answers

Why is Prussian blue used on cone and hub faces?

To check the degree of mating after installation. (B) Signup and view all the answers

What material is the rear cone for center hub placement made of?

Bronze (A) Signup and view all the answers

What is the role of the removable bushing in a taper bore application?

To provide a bearing surface for blade rotation. (D) Signup and view all the answers

What is typically checked during general propeller installation?

The correct indexing position of the prop. (A) Signup and view all the answers

In the context of propellers, what does composite material typically refer to?

Fiberglass reinforced components. (D) Signup and view all the answers

Which method can be used to enhance the durability of metal propeller surfaces?

Shot peening process. (A) Signup and view all the answers

What is the purpose of using tapered cones during installation?

To align the hub on the prop shaft accurately. (C) Signup and view all the answers

What primary purpose does shot peening serve in metal propeller construction?

To enhance the surface hardness and fatigue resistance (B) Signup and view all the answers

Which composite material is NOT mentioned as being used in the construction of propeller blades?

Aluminium (B) Signup and view all the answers

In which of the following methods is a foam core placed to resist distortion in composite propellers?

Shaping composite material around an aluminum-alloy spar (C) Signup and view all the answers

What is the role of the polyurethane foam filling in Fibre-Reinforced Plastic (FRP) moulding?

To improve resistance to distortion caused by operating stresses (B) Signup and view all the answers

Which of the following statements about fibre-reinforced plastic (FRP) blades is true?

Kevlar layers are placed lengthwise and multidirectionally for strength (D) Signup and view all the answers

What is a common characteristic of the materials used in constructing composite propellers?

They are all reinforced with plastic resins and fibers (B) Signup and view all the answers

Which feature is crucial in the retention of composite materials on the shank of a propeller?

External composite windings and clamping action of hub halves (B) Signup and view all the answers

What is a significant advantage of using composite materials in propeller construction?

Resistance to distortion from operating stresses (C) Signup and view all the answers

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Study Notes

Fixed Pitch Metal Propellers

Aluminum alloy propellers are strong and malleable, extending to the propeller hub
Anodizing creates a hard coating on aluminum blades which is corrosion resistant, waterproof, and airtight.
Shot peening is a surface treatment that distributes stress and increases fatigue strength, especially for steel propellers which are brittle.
Shot peening is done by blasting small beads of steel or glass onto the surface of the propeller.

Composite Propellers

Blades can be constructed with fiberglass, Kevlar, carbon, or boron fibers.
One method of constructing composite blades involves wrapping these fibers around an aluminum-alloy spar with foam in the leading and trailing edges.
The second method uses a composite shell with a foam core.
Fibre-reinforced plastic (FRP) blades consist of a laminated Kevlar shell with a foam core.
Kevlar is layered in multiple directions to boost the strength of the shell.
The leading and trailing edges are reinforced with solid Kevlar to resist flexing and buckling.

Propeller Installation

Tapered cones are used on the front and back of the hub to center it on the prop shaft.
Prussian blue is used to check the degree of mating between the cones and hub after the prop-retaining nut has been tightened.
A protective cap should be fitted to the prop shaft threads to prevent damage during installation.
In variable-pitch propellers, a removable bushing is fitted into the blade butt to provide a bearing surface for the blades.
This bushing also allows for the fitment of a plug that balances the blades statically.

Propeller Construction

The spider forging is the main component that connects the blades to the propeller hub.

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