AVIATION 1035: Rotary Wing Aerodynamics
47 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

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?

<p>The rotor speed and main rotor mass (C)</p> Signup and view all the answers

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

<p>Counterclockwise (D)</p> Signup and view all the answers

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

<p>To produce thrust that counteracts the main rotor torque (C)</p> Signup and view all the answers

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

<p>To reduce shock and limit travel in certain directions (A)</p> Signup and view all the answers

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

<p>The force causing the fuselage to rotate opposite the rotor blades (B)</p> Signup and view all the answers

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

<p>Semi-Rigid Rotor System (D)</p> Signup and view all the answers

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

<p>Tail rotor force counteracts the torque produced by the main rotor (B)</p> Signup and view all the answers

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

<p>They can absorb vibration without regular lubrication (B)</p> Signup and view all the answers

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

<p>By flexing to absorb forces, reducing the need for hinges and bearings (D)</p> Signup and view all the answers

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

<p>The amount of noise and vibration produced (D)</p> Signup and view all the answers

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

<p>Movement limitations imposed by dampers and stops (A)</p> Signup and view all the answers

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

<p>Enhanced flexibility to absorb forces (C)</p> Signup and view all the answers

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

<p>Elastomeric bearings require regular lubrication. (A)</p> Signup and view all the answers

What design feature of a Fenestron® reduces ground hazards?

<p>It has enclosed rotating blades in a shroud. (A)</p> Signup and view all the answers

How does the NOTAR® system generate thrust?

<p>By venting air from adjustable slots. (B)</p> Signup and view all the answers

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

<p>To counteract torque of the main rotor. (D)</p> 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?

<p>Coanda Effect. (A)</p> Signup and view all the answers

What does NOTAR® stand for?

<p>No Tail Rotor. (B)</p> Signup and view all the answers

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

<p>To create additional thrust against the main rotor's torque. (D)</p> Signup and view all the answers

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

<p>Fenestron®. (B)</p> Signup and view all the answers

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

<p>Lowers drag in flight. (C)</p> Signup and view all the answers

How does the pilot control the anti-torque system?

<p>Using foot pedals similar to rudder pedals. (B)</p> Signup and view all the answers

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

<p>It has a three-bladed design (D)</p> Signup and view all the answers

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

<p>Loss of engine power due to drag from the tail rotor (B)</p> Signup and view all the answers

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

<p>Fenestron® or fan-in-tail design (B)</p> Signup and view all the answers

Where is the horizontal stabilizer typically located on helicopters?

<p>On the tail cone or pylon (C)</p> Signup and view all the answers

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

<p>They are open tipped with variable pitch (A)</p> Signup and view all the answers

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

<p>Injury from spinning blades (C)</p> Signup and view all the answers

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

<p>To counteract main rotor torque (B)</p> Signup and view all the answers

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

<p>Through a variable-pitch blade fan and the Coanda Effect (C)</p> Signup and view all the answers

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

<p>The vertical stabilizers (C)</p> Signup and view all the answers

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

<p>To pressurize the tailboom and expel air for the Coanda Effect (C)</p> Signup and view all the answers

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

<p>It induces the Coanda Effect for boundary-layer control (D)</p> Signup and view all the answers

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

<p>Dual rotor helicopters like the Chinook (C)</p> Signup and view all the answers

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

<p>It allows the tailboom to act like a wing, providing anti-torque (B)</p> Signup and view all the answers

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

<p>Causes the helicopter to rotate uncontrollably (A)</p> Signup and view all the answers

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

<p>Kamov Ka-52 (B)</p> Signup and view all the answers

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

<p>To increase or decrease lift (B)</p> Signup and view all the answers

Which helicopter is designed as a tilt-rotor aircraft?

<p>MV-22 Osprey (A)</p> Signup and view all the answers

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

<p>They change the angle of the tail rotor's pitch (D)</p> Signup and view all the answers

What does the cyclic control do in a helicopter?

<p>Tilts the rotor plane for directional movement (C)</p> Signup and view all the answers

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

<p>Kamov Ka-32A-12 (D)</p> Signup and view all the answers

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

<p>To control engine power output (A)</p> Signup and view all the answers

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

<p>Eurocopter X3 (A)</p> Signup and view all the answers

Flashcards

Fully Articulated Rotor System

A main rotor system with multiple hinges allowing blades to move independently in all directions.

Elastomeric Bearings

A design principle for reducing vibrations and noise in a helicopter.

Fletxures

Composites designed to flex and absorb forces, replacing hinges and bearings.

Semi-Rigid Rotor System

Main rotor system where the hub and blades can tilt like a seesaw.

Signup and view all the flashcards

Drag Hinge and Pitch Change Rods

Hub components that allow the blade to flap up and down and move laterally.

Signup and view all the flashcards

Blade Flapping

The act of blades flapping up and down due to lift and drag forces.

Signup and view all the flashcards

Blade Hunting

Blades moving out of their intended plane of rotation due to unequal forces.

Signup and view all the flashcards

Dissymmetry of Lift

Unequal lift forces on the blades due to their different positions during rotation.

Signup and view all the flashcards

Torque

The force that acts on a helicopter's fuselage in the opposite direction of the main rotor's rotation, caused by the conservation of angular momentum.

Signup and view all the flashcards

Anti-torque System

A system designed to counter the torque force generated by the main rotor, preventing the helicopter from spinning out of control.

Signup and view all the flashcards

Tail Rotor

A set of blades located at the end of a helicopter's tail boom that generate thrust to counteract torque.

Signup and view all the flashcards

Anti-torque Thrust

The force generated by the tail rotor that acts in the opposite direction of the torque force.

Signup and view all the flashcards

Tail Rotor Torque

The measure of the force being applied by the tail rotor multiplied by the distance between the tail rotor and the main rotor.

Signup and view all the flashcards

Main Rotor Blades

Made from a composite structure, these blades are responsible for providing lift to the helicopter.

Signup and view all the flashcards

Main Rotor Torque

The force that is generated by the main rotor blades, causing the helicopter to spin in the opposite direction.

Signup and view all the flashcards

Fenestron®

A tail rotor design that uses a multibladed ducted fan mounted in the vertical pylon to provide sideways thrust that counters the torque produced by the main rotor.

Signup and view all the flashcards

NOTAR® System

A system that uses an engine-driven adjustable fan located inside the tail boom to counteract the torque of the main rotor, without a visible tail rotor.

Signup and view all the flashcards

Coanda Effect

A phenomenon where a fluid flowing over a curved surface tends to follow the surface, creating a low-pressure area on one side.

Signup and view all the flashcards

NOTAR® Tail Boom Air Flow

Air is vented out of two long slots on the right side of the tail boom, entraining main rotor wash to hug the right side of the tail boom, creating a low pressure area. This creates a force that counteracts the torque of the main rotor.

Signup and view all the flashcards

NOTAR® Thrust Generation

The remaining air from the fan in a NOTAR® system is sent through the tail boom to a vent on the aft left side of the boom where it is expelled. This creates thrust that helps to further counteract the torque of the main rotor.

Signup and view all the flashcards

NOTAR (No Tail Rotor)

A system that uses the Coanda Effect to create a horizontal jet of air that flows along the tailboom, providing anti-torque.

Signup and view all the flashcards

Direct Jet Thruster

A type of anti-torque system that uses a jet of air directed toward the tail, providing control.

Signup and view all the flashcards

Downwash

The system that manages the downward flow of air from the main rotor.

Signup and view all the flashcards

What is the purpose of an anti-torque system?

The system that counteracts the torque produced by the main rotor, preventing the helicopter from spinning in the opposite direction.

Signup and view all the flashcards

How is the anti-torque system controlled?

The anti-torque system on helicopters is controlled using foot pedals, similar to rudders on a plane.

Signup and view all the flashcards

How does the anti-torque system work?

The pitch of the tail rotor blades is adjusted to change the amount of thrust generated, which in turn controls the helicopter's yaw (rotation about its vertical axis).

Signup and view all the flashcards

What are some potential issues with tail rotors?

The tail rotor blades are deadly if someone walks into them, and the tail rotor creates drag and takes power from the engine, especially during forward flight.

Signup and view all the flashcards

What is the role of a vertical fin or pylon on a helicopter?

A vertical fin or pylon supports the tail rotor assembly, often with a horizontal stabilizer at the tail cone for added stability.

Signup and view all the flashcards

What's another type of anti-torque system?

A 'fan-in-tail' design, also known as the Fenestron®, is an alternative to traditional tail rotors.

Signup and view all the flashcards

What are the advantages of a Fenestron?

The Fenestron design, unlike traditional tail rotors, reduces noise considerably and improves safety as the blades are enclosed.

Signup and view all the flashcards

How does a Fenestron anti-torque system work?

The Fenestron system uses a ring of blades within a shroud to generate the counter-torque force.

Signup and view all the flashcards

Coaxial Rotors

A type of anti-torque system where two rotors rotate in opposite directions, effectively canceling out the torque.

Signup and view all the flashcards

Collective Pitch Control

A control system that enables the pilot to adjust the pitch of all the main rotor blades simultaneously, effectively controlling the helicopter's lift.

Signup and view all the flashcards

Cyclic Pitch Control

A control system that allows the pilot to tilt the plane of rotation of the main rotor blades, changing the direction of the helicopter's movement.

Signup and view all the flashcards

Anti-Torque Control

A control system that allows the pilot to adjust the pitch of the tail rotor blades, thereby controlling the yaw (rotation around its vertical axis) of the helicopter.

Signup and view all the flashcards

Cyclic

The main control stick used in helicopters, located between the pilot's legs, and used to control the cyclic pitch of the main rotor.

Signup and view all the flashcards

Collective

A control lever used in helicopters to control the collective pitch of the rotor blades, affecting lift and altitude.

Signup and view all the flashcards

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.

Quiz Team

Related Documents

Rotary Wing Aerodynamics PDF (AVIA-1035)

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.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser