INTRODUCTION TO HELICOPTERS

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INTRODUCTION TO HELICOPTERS

• Course Presentation
• Divahar J
• ME-AEROSPACE
• INDIAN INSTIUTE OF SCIENCE

2
Organization

• Forces on Helicopter
• Helicopter and Aircraft
• Helicopter Flight Modes
• Blade Collapsing
• Controls
• Gyroscopic precession
• Helicopter stability

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HELICOPTER FLIGHT
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Forces On A Helicopter
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Helicopter And Aircraft

• Weight and drag ? as usual
• lift and thrust from same means
• No separate mechanism
• Called MAIN Rotor (There is Tail Rotor too)
• Rotor ? rotating wings
• Concurrent wings !

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Helicopter And Aircraft

• lift and drag can be controlled Independently
• So forward and vertical flight
• Hovering is possible
• Only one means
• Rotor tilting essential
• Tail Rotor is also needed
• Complicates flight and controls Independently

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Helicopter Flight Modes

• Vertical flight
• Hovering
• Ascending
• Descending
• Lateral flight
• Forward Flight
• Sideward Flight
• Rearward

• Rotations
• Pitch
• Roll
• Yaw
• Autorotation

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Vertical Flight
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Lateral Flight
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VTOL Aircrafts
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Types of Rotor

• Articulated rotor
• Teetering Rotor
• Hingeless Rotor
• Bearingless Rotor

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Teetering Rotor

• Four bladed teetering rotor

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Blade Collapsing
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Blade Collapsing
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Controls

• Throttle
• cyclic and collective controls
• Pitch
• Roll
• Antitorque Control
• To avoid fuselage spin
• Yaw

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Cyclic and collective controls

• Swash Plate
• Push pull rod
• Have hydraulic assistance
• Swash Plate less
• Solid State Adaptive Rotor (SSAR)
• (Controlled Twisting)

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Collective Control
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Collective Control

• Howstuffworks.com Video for collective control
• Link http//travel.howstuffworks.com/helicopter6.
  htm

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Collective Control

• Howstuffworks.com Video for collective control
• Link http//travel.howstuffworks.com/helicopter6.
  htm

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Cyclic Control
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Cyclic Control

• Howstuffworks.com Video for collective control
• Link http//travel.howstuffworks.com/helicopter6.
  htm

22
Cyclic Control

• Howstuffworks.com Video for collective control
• Link http//travel.howstuffworks.com/helicopter6.
  htm

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Antitorque Control

• Torque applied
• Equal and opposite reaction
• Antitorque Rotor
• NOTOR

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Antitorque Rotor

• Antitorque Rotor (Tail Rotor)
• Conventional
• Fenestron (Fantail)

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NOTOR

• NOTOR
• No-Rotor
• Utilizes Gonda effect
• NOTE
• Tip Jet driven main rotors
• Contra Rotating main rotors

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Gonda effect

• Tendency of the fluid to remain attached with the
  curved surface instead of flowing straight
• Newtons 3rd law ?Net Force
• Easy Home Experiment
• Spoon

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NOTOR
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NOTOR
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Control Assembly
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Gyroscopic Precession

• The result of applying a force or moment against
  a rotating body occurs 90 later in the direction
  of rotation
• All will be ANTICLOCKWISE for moments in a RHC

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Gyroscopic Precession
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Gyroscopic Precession

• Offset control linkage needed to avoid pilot
  confusions
• Or else, ? tilt swash plate to left if rotor is
  to be tilted forward

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Gyroscopic Precession
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Take-off and Landing
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Lets Recall.
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Pendular Action and Helicopter Stability

• Any hanging body will have stability
• Same as PENDULUM
• The fuselage of the helicopter is suspended from
  a single point and has considerable mass.
• After oscillations will come back to original
  state

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Pendular Action and Helicopter Stability
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Pendular Action and Helicopter Stability
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? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ?

• QQQ ?

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• Thank Q