AVIATION HISTORY

WEEK 10

Helicopters

Helicopters

Introduction How a helicopter flies The advantages of Helicopter

Introduction

Helicopter is an aircraft than can take-off and land vertically.

They have existed for 70 years & become one of the most versatile and vital vehicles in the world.

Early helicoptersFirst flown in 1936

Basic Helicopter

Rotor: The rotating part of any device

Basic Helicopter

Main Rotor Long, flat blades that spin & give a helicopter lift

& thrust. It determine the helicopter direction.

Drive Shaft Long cylindrical rotating rod for the transmission

of power. Tail Rotor

A small rotor at the back. It blow air sideways to give balance .

Without tail rotor, the torque would force the helicopter body to rotate in the opposite direction.

It also used to turn the helicopter

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 does Helicopter Flies?

How helicopter flies? The helicopter engines will provide the energy/power to

turn the main rotor blades. As the rotor blades turn it will create Lift and Thrust force. The rotor blades have an airfoil shape, so as the rotors

turn, air flows more quickly over the tops of the blades than the below.

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

This difference in pressure pushes the blades up and gives the helicopter the lift it needs to fly.

However, when the rotor blades turns, it also produces reaction torque which tends to make the helicopter’s body spin also.

So, the tail rotor at the back is used to prevent the helicopter’s body to spin.

On twin-rotor blades the rotors turn in opposite directions, so their reactions cancel each other.

The helicopters can change their direction by changing pitch angle of the helicopter’s rotor blades.

Basic Helicopter

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

Can hover (can remain in one place in the air)

Can fly backwards (reverse) Can rotate in the air (360 degrees)

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

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.

Flexible 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 congested or isolated areas and deep jungle.