AVIATION HISTORYLecture 3c: Helicopters

By Zuliana

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 and rescue.

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 most versatile and vital vehicles in the world.

Early helicoptersFirst flown in 1936

Cockpit

Rotor Blades

TailRotor

Landing Skids

Basic Helicopter Rotor Blades

Long, flat blades that spin & give a helicopter lift & thrust.

It determine the helicopter direction.

Tail Rotor A small rotor at the back. Generate balance force (horizontal

force) to help helicopter fly stably. It also used to change the helicopter’s

direction.

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?

A helicopter doesn’t require a runway to take-off into the air, so the rotation of its rotor blades generates lift force.

When the lift force is greater than the helicopter’s weight, it will fly up vertically.

How helicopter fly vertically? The helicopter engines will provide the power to

turn the main rotor blades. The rotor blades have an airfoil shape, so as the

rotors turn, air velocity over the tops of the blades is higher than the below.

Thus, the pressure of the slower moving air flowing under the blade is greater than the above.

This difference in pressure pushes the 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 turns, it also make the helicopter’s body tend to spin also.

So, the tail rotor at the back is used to give balance force in order to prevent the helicopter’s body to spin.

For helicopter fly vertically, the pilot has to push/pull the ‘collective’ 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 ‘cyclic’ in the required direction.

To move forward, pilot has to move the ‘cyclic’ 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.

More Lift Force

Thrust

How helicopter move backward

To move backward, pilot has to move the ‘cyclic’ 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.

More Lift Force

Thrust

Helicopter move side to side

To move right, pilot has to move the ‘cyclic’ control stick to the right.

It will make the rotor blades tilted to the right, which lead to the differences of lift force generated.

As a result, it will create a sideways force, which moves the helicopter to the right.

More Lift Force

Sideways force

Helicopter move side to side

To move left, pilot has to move the ‘cyclic’ control stick to the left.

It will make the rotor blades tilted to the left, which lead to the differences of lift force generated.

As a result, it will create a sideways force, which moves the helicopter to the left.

More Lift Force

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

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

connected to long cables. Are also used to place heavy equipment on

the tops of tall buildings.

The Uses of Helicopter

Search and Rescue Helicopters Used for emergency 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.

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 targets.

Transport helicopters are used to carry troops and supplies when transport via typical military cargo is not possible.

What are the advantages of 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. A helicopter can do all this plus has the

ability to fly backwards, rotate 360 degrees on the spot and hover (can remain still)

Helicopters may be limited in their speed, but the incredible maneuverability mentioned above 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 the air) The capability to efficiently hover for

extended periods of time, reverse and rotate allows a helicopter to accomplish tasks that airplane cannot perform.

Advantages of Helicopter

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 burning buildings.