AVIATION 1035: Rotary Wing Aerodynamics

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the anti-torque system in a helicopter?

To stabilize the fuselage during landing

To enhance lift during flight

To counteract the torque produced by the main rotor blades (correct)

To increase engine power

According to Newton's third law, what occurs when power is applied to the rotor system?

The rotor system generates more lift

There is an equal and opposite reaction in the fuselage (correct)

The helicopter accelerates forward

The main rotor spins faster without consequence

How many main rotor blades do helicopters typically have?

Five to ten

One to two

Three to eight

Two to seven (correct)

What creates the torque that tries to spin the fuselage of a helicopter?

The rotor speed and main rotor mass Signup and view all the answers

If the main rotor of a helicopter rotates clockwise, which direction will the fuselage tend to rotate?

Counterclockwise Signup and view all the answers

What is the role of the tail rotor in a helicopter?

To produce thrust that counteracts the main rotor torque Signup and view all the answers

What is the primary purpose of dampers and stops in a Fully Articulated Rotor System?

To reduce shock and limit travel in certain directions Signup and view all the answers

What is meant by the term 'torque' in relation to helicopter flight?

The force causing the fuselage to rotate opposite the rotor blades Signup and view all the answers

Which rotor system design features a two-blade main rotor that can teeter like a seesaw?

Semi-Rigid Rotor System Signup and view all the answers

What is the relationship between tail rotor force and torque in helicopters?

Tail rotor force counteracts the torque produced by the main rotor Signup and view all the answers

What is one advantage of elastomeric bearings in main rotor systems compared to steel bearings?

They can absorb vibration without regular lubrication Signup and view all the answers

How do modern helicopter main rotors with flextures improve rotor system design?

By flexing to absorb forces, reducing the need for hinges and bearings Signup and view all the answers

Which aspect of helicopter engineering are designers aiming to minimize in main rotor systems?

The amount of noise and vibration produced Signup and view all the answers

What is a characteristic feature of the Fully Articulated Rotor System?

Movement limitations imposed by dampers and stops Signup and view all the answers

What benefit does the use of advanced composite materials in rotor hubs provide?

Enhanced flexibility to absorb forces Signup and view all the answers

Which of the following statements about helicopter rotor systems is NOT true?

Elastomeric bearings require regular lubrication. Signup and view all the answers

What design feature of a Fenestron® reduces ground hazards?

It has enclosed rotating blades in a shroud. Signup and view all the answers

How does the NOTAR® system generate thrust?

By venting air from adjustable slots. Signup and view all the answers

What is the primary function of the high volume of air created by the NOTAR® fan?

To counteract torque of the main rotor. Signup and view all the answers

What effect does the air venting from the slots on the right side of the NOTAR® tail boom rely on?

Coanda Effect. Signup and view all the answers

What does NOTAR® stand for?

No Tail Rotor. Signup and view all the answers

What is the role of the air expelled from the aft left side of the NOTAR® tail boom?

To create additional thrust against the main rotor's torque. Signup and view all the answers

Which of the following systems employs a multibladed ducted fan design?

Fenestron®. Signup and view all the answers

What is a significant advantage of using a shroud in rotor design?

Lowers drag in flight. Signup and view all the answers

How does the pilot control the anti-torque system?

Using foot pedals similar to rudder pedals. Signup and view all the answers

What is a specific feature of the tail rotor on the Aerospatiale SA-315B helicopter?

It has a three-bladed design Signup and view all the answers

What problem can arise when the helicopter is in forward flight with the vertical fin used?

Loss of engine power due to drag from the tail rotor Signup and view all the answers

What is an alternative design to the traditional tail rotor system?

Fenestron® or fan-in-tail design Signup and view all the answers

Where is the horizontal stabilizer typically located on helicopters?

On the tail cone or pylon Signup and view all the answers

What is a characteristic of the tail rotor blades mentioned in the content?

They are open tipped with variable pitch Signup and view all the answers

What type of danger is associated with the tail rotor system?

Injury from spinning blades Signup and view all the answers

What is the primary purpose of the anti-torque system in helicopters?

To counteract main rotor torque Signup and view all the answers

How does the NOTAR system generate the anti-torque needed during a hover?

Through a variable-pitch blade fan and the Coanda Effect Signup and view all the answers

In forward flight, what primarily provides the anti-torque function?

The vertical stabilizers Signup and view all the answers

What is the role of the variable-pitch composite blade fan in the anti-torque system?

To pressurize the tailboom and expel air for the Coanda Effect Signup and view all the answers

What happens to the airflow created by the NOTAR system as it exits the tailboom?

It induces the Coanda Effect for boundary-layer control Signup and view all the answers

Which helicopter design requires no anti-torque rotor due to its configuration?

Dual rotor helicopters like the Chinook Signup and view all the answers

What is the effect of the Coanda Effect on the helicopter's tailboom during a hover?

It allows the tailboom to act like a wing, providing anti-torque Signup and view all the answers

What is the consequence of the main rotor torque in a helicopter?

Causes the helicopter to rotate uncontrollably Signup and view all the answers

Which helicopter utilizes coaxial rotors for its anti-torque system?

Kamov Ka-52 Signup and view all the answers

What is the primary function of the collective control in a helicopter?

To increase or decrease lift Signup and view all the answers

Which helicopter is designed as a tilt-rotor aircraft?

MV-22 Osprey Signup and view all the answers

How do foot pedals function in a helicopter's control system?

They change the angle of the tail rotor's pitch Signup and view all the answers

What does the cyclic control do in a helicopter?

Tilts the rotor plane for directional movement Signup and view all the answers

Which of the following helicopters is known for its coaxial rotor system?

Kamov Ka-32A-12 Signup and view all the answers

What is the role of the throttle control in a helicopters collective?

To control engine power output Signup and view all the answers

Which helicopter features an advanced rotor system improving speed and maneuverability?

Eurocopter X3 Signup and view all the answers

Study Notes

Rotary Wing Aerodynamics

This is an AVIATION 1035 course at Fanshawe College.

Fully Articulated Rotor System

Various dampers and stops are used in different designs to minimize shock and limit movement in certain directions.
Figure 1-98 demonstrates a fully articulated main rotor system with the discussed features.

Main Rotor Systems

Different types of main rotor systems exist with various designs and variations.
Engineers continually develop methods for reducing vibrations and noise from rotating helicopter components.
Hinges and their movement are displayed in Figure 5-82.
Figure 5-83 presents a Eurocopter model 725 main rotor head, including drag hinges and pitch change rods.
The Semi-Rigid Rotor system uses a two-blade main rotor.
In this system, the blades are rigidly attached to a hub which pivots like a seesaw.

Main Rotor Bearings

The use of elastomeric bearings is becoming more prevalent in main rotor systems.
These polymer bearings' ability to deform and return to their original shape allows them to absorb vibrations, preventing these vibrations from being transmitted by steel bearings and reducing maintenance.
They do not require regular lubrication.

Main Rotor Flextures

Modern helicopters utilize flextures (hubs and hub components constructed from advanced composite materials) in main rotor systems.
Advanced composite materials enable flexibility, absorbing blade hunting and lift dissymmetry forces.
The use of flextures simplifies designs by eliminating hinges and bearings.
This simplifies the rotor mast and reduces maintenance because fewer moving parts are involved.

Elastomeric Bearings on Flextures

Designs incorporating flextures often use elastomeric bearings.
Figure 1-99 shows a "STARFLEX" rotor hub with elements: laminated spherical stop (thrust bearing), star arm, sleeves, and elastomer blocks (frequency adapters).

Anti-Torque System

Helicopters typically have between two and seven main rotor blades constructed from composite materials.
A large rotating mass on the main rotor blades generates torque.
Newton's third law applies: every action has an equal and opposite reaction.
The tendency of the helicopter fuselage to move in the opposite direction of the rotor is known as torque.
The force generated by the main rotor is countered by an anti-torque system, such as the tail-boom and tail rotor.
The tail rotor has blades at the end of the tail boom.
The tail rotor's force and the distance from the tail to the main rotor determines the torque opposing the main rotor.
The counter-torque of the tail rotor is controlled by foot pedals, which change the pitch of the tail rotor blades.
Foot pedals adjust as engine power changes.
This adjustment allows precise vertical control.
A more advanced design for anti-torque, called a Fenestron®, or fan-in-tail design, uses enclosed blades in a shroud, reducing ground hazards and drag. This is seen in Figure 5-87
NOTAR® (No Tail Rotor) systems have a fan inside the tail boom driven by the main engine for counter-torque. Air is ejected in controlled ways to generate the anti-torque thus avoiding the need for a traditionally mounted tail rotor.

Anti-Torque System - Additional Features

Some helicopters counteract torque by employing two main rotors spinning in opposite directions enabling self-cancellation of torque.
The Coanda Effect explains how air directed from the tail generates a pressure difference, enabling anti-torque.
In forward flight, vertical stabilizers usually play a significant role in anti-torque.

Helicopter Controls

Helicopter controls differ slightly from fixed-wing aircraft.
The collective (operated by the pilot) influences lift by altering the angle of attack of all rotor blades.
The cyclic (located between the pilot's legs) tilts the plane of rotor blade rotation to provide directional control
Foot pedals control the pitch of tail rotor blades.
Figures 1-103 and 1-104 illustrate controls.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the concepts of rotary wing aerodynamics as part of the AVIATION 1035 course at Fanshawe College. It covers various aspects of fully articulated rotor systems, the engineering challenges of rotor design, and advancements in main rotor bearings and vibration reduction techniques.