lecture 5 helicopters

8/7/2019 Lecture 5 Helicopters

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AVIATION HISTORY

Lecture 5: Helicopters

By Zuliana Ismail,2010



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.



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



Cockpit

Rotor

Blades

Tail

Rotor

Landing

Skids



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.



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.



How helicopter fly vertically?



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.



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.



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



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



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



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



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




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.




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.




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.



What are the advantagesof the helicopter compare

to airplane



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



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.



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.




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.

lecture 5 helicopters

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