Lecture 5 Helicopters
Transcript of Lecture 5 Helicopters
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AVIATION HISTORY
Lecture 5: Helicopters
By Zuliana Ismail,2010
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Introduction
Helicopters truly are amazing aircraft, and how
helicopters fly is what makes them such versatile
machines, being perfectly suited to roles ranging
from military use to fire fighting and search andrescue.
Helicopters have been around for centuries - well,
the principle anyway - but it was Russian aircraft
pioneer Igor Sikorsky who designed, built and in 1939 flew the first fully controllable single rotor / tail
rotor helicopter - the fundamental concept that would
shape all future helicopters.
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Introduction
Helicopter is an aircraft than can take-off
and land vertically.
Nowadays, they became one of the mostversatile and vital vehicles in the world.
Early helicopters
First flown in 1936
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Cockpit
Rotor
Blades
Tail
Rotor
Landing
Skids
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Basic Helicopter
Rotor Blades Long, flat blades that spin & give a
helicopter lift & thrust.
It determine the helicopter direction.
T ail Rotor
A small rotor at the back.
Generate balance force (horizontal force)to help helicopter fly stably.
It also used to change the helicopter¶sdirection.
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Basic Helicopter
Engines
Used to power the helicopter.
Cockpit
The area where the pilot sits and control the helicopter.
Cabin
The area where passengers or other things are carried.
Landing Skids Long metal feet for helicopters stand on when they are
on the ground.
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How helicopter fly vertically?
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How helicopter fly vertically? The helicopter engines will provide the power to tur n
the main rotor blades. The rotor blades have an airfoil shape, so as the
rotors turn, air velocity over the tops of the blades ishigher than the below.
Thus, t he pressure of t he slower moving air flowing under t he blade is greater t han t he above.
This difference in pressure pushes t he blades up and gives the helicopter the lift it needs to fly.
When Lift force is greater than helicopter¶s weight,it will fly up vertically.
However, when the rotor blades tur ns, it also make thehelicopter¶s body tend to spin also.
So, the tail rotor at the back is used to give balanceforce in order to prevent the helicopter¶s body to spin.
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For helicopter fly vertically, the pilot has topush/pull the µcollective¶ control stick.
While, to move forward, backward, or to the
side, the pilot uses the "cyclic" which is usually
mounted between the legs.
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How helicopter move forward
Direction of lift force can be changed by moves the µcyclic¶
in the required direction.
To move forward, pilot has to move the µcyclic¶ control
stick to the front.
It will make the rotor blades tilted to the front, which lead
to the differences of lift force generated.
As a result, it will create a forward force (thrust), which
moves the helicopter forward.
Thrust
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How helicopter move backward
To move backward, pilot has to move the µcyclic¶ control
stick to the back. It will make the rotor blades tilted to the back, which lead to
the differences of lift force generated.
As a result, it will create a backward force (thrust), which
moves the helicopter backward.
Thrust
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Helicopter move side to side
To move right, pilot has to move the µcyclic¶ control
stick to the right.
It will make the rotor blades tilted to the right, whichlead to the differences of lift force generated.
As a result, it will create a sideways force, which
moves the helicopter to the right.
Sideways force
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Helicopter move side to side
To move left, pilot has to move the µcyclic¶ control stick
to the left.
It will make the rotor blades tilted to the left, whichlead to the differences of lift force generated.
As a result, it will create a sideways force, which
moves the helicopter to the left.
Sideways force
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The Uses of Helicopter
ConstructionCommercial
FirefightingSearch &Rescue
Military
Bell 205 dropping water
on fire
Sikorsky S-64 Skycrane lifting
a mock-up house
WAH-64 Apache attack helicopter
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The Uses of Helicopter
Commercial Helicopters
Mainly used for transport.
Construction Helicopters
Helicopter that are used in construction to carry
loads are called skycranes.
The heavy loads carried by skycranes are connectedto long cables.
Are also used to place heavy equipment on the tops
of tall buildings.
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The Uses of Helicopter
Search and Rescue Helicopters
Used for emer gency medical assistance when an
ambulance cannot easily or quickly reach the scene.
Firefighting Helicopters
Used to combat fires.
These helicopters are often called Helitacks.
Helitacks carry water to perform water bombing onto
the fire.
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The Uses of Helicopter
Military Helicopters
Are used mainly for attack and for transport.
Attack helicopters are equipped with missile or miniguns which are used to attack ground tar gets.
Transport helicopters are used to carry troops and
supplies when transport via typical military car go is
not possible.
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What are the advantagesof the helicopter compare
to airplane
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Bell UH-1 Iroquois (Huey)- The most famous
helicopter in the world with several unique
characteristics
Serve as medical evacuation , instrument trainer and
general utility aircraft
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Advantages of Helicopter
A normal airplane can fly forward, up,
down, left and right.
Ahelicopter can do all this plus has the abilityto fly backwards, rotate 360 degrees on
the spot and hover (can remain still)
Helicopters may be limited in their speed, but
the incredible maneuverability mentionedabove is what makes them so useful in so
many situations.
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Summary of helicopter advantages
Can fly backwards (reverse)
Can rotate in the air (360 degrees)
Can hover (can remain in one place in theair)
The capability to efficiently hover for extended
periods of time, reverse and rotate allows a
helicopter to accomplish tasks that airplanecannot perform.
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Advantages of Helicopter
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Advantages of Helicopter
Flexible (doesn¶t require runway)
As helicopter do not need runway for take-off and
landing, it can fly almost anywhere.
Can deliver huge loads to areas that no other
vehicle can reach. For example crowd areas,
isolated areas and deep jungle.
Versatile (able to perform many functions)
Helicopter functions include transportation,construction, fight fires, search and rescue,
military uses and also can rescue people trapped
in bur ning buildings.