Aircraft propulsion

DEFINITION

AIRCRAFT

A machine that is able to fly by

gaining support from the air.

PROPULSION

The word is derived from two Latin

words: pro meaning before or forwards and

pellere meaning to drive.

Propulsion means to push forward or drive an

object forward.

AIRCRAFT PROPULSION

Lift – the force the causes an aircraft to

overcome gravity, climb into the air and stay in

the air.

Weight – the force generated by the

gravitational attraction of the earth on

the aircraft.

Thrust – the force which moves an aircraft

through the air.

Drag - forces acting opposite to the relative

motion of any object moving.

EXAMPLES OF AIRCRAFT

AIRPLANE

TRIVIA

It is a Boeing VC-25, a military

version of Boeing 747.

A plane can only use the call sign

“Air Force One” if it is a military

aircraft attached to the 89th Air Lift

Wing and only when the President

of the United States is on board.

HOT AIR BALLOON

TRIVIA

The first human carrying flighttechnology.

The large balloon on top is called an“envelope”. It holds hot air created by aheat source known as a burner.

Hot air balloons can fly to amazingheights, the world record is over21,000 meters.

AIRSHIP

TRIVIA

Also called as Blimps

These airships are filled with helium.The helium is maintained underlow pressure.

Goodyear Blimps uses this foradvertising purposes and for use asa television camera platform for aerialviews of sporting events.

SEAPLANES

TRIVIA

Powered fixed-wing aircraft capable

of taking off and landing on water.

Motor-powered watercraft which

uses hydrofoils to levitate their main

hull above the water when running

at a speed.

HELICOPTER

HISTORY

The earliest known mention of a rotor-

powered flying machine appears in a Chinese

text written about A.D. 320. The design of this

machine may have been based on a Chinese

toy called the flying top. Such toys flew by

means of feather rotors. In 1483, Leonardo da

Vinci sketched a design for a helicopter. It had

a large screw-like wing made of starched

linen. In 1784, two Frenchmen named Launoy

and Bienvenu built the first model helicopter

in Europe that could fly.

Da Vinci’s sketch

Model of Helicopter from

Launoy and Bienvenu

HISTORYBy early 1900’s, small, powerful petrol

engines had been developed that made

manned helicopter flight possible. The first

ever was in 1907. The craft was a four-rotor

helicopter built by Louis Breguet, a French

Inventor. This helicopter lifted a human about

61 centimeters for a minute. Later in 1907, a

French mechanic name Paul Cornu made the

first free flight in a helicopter. He flew his

tandem-rotor aircraft 2 meters for about 20

seconds.

Paul Cornu in

his

first helicopter

Full length photograph

TYPES OF HELICOPTERS

SINGLE-ROTOR HELICOPTER

Has one main rotor mounted above its body. Italso has a second, smaller rotor mounted onits tail. The main rotor may have 2 to 8 blades.It provides the helicopter’s lifting-power. Thetail rotor has from 2 to 13 blades. It is mountedvertically on the either side of the tail and sospins at a right angle to the main rotor. The tailrotor is used to control direction. It alsoovercomes the tendency of the helicopter tospin around.

TWIN-ROTOR HELICOPTER

Have 2 main rotors. The rotors turn in opposite

directions and so it doesn’t need for a tail rotor.

There are 2 types: The tandem-rotor helicopter

which has a main rotor mounted above each

end of the body and the coaxial-rotor helicopter

which has one rotor above the other.

SINGLE-ROTOR HELICOPTER

TWIN-ROTOR HELICOPTERS

Tandem-rotor

Helicopter

Coaxial-rotor

Helicopter

HELICOPTER PROPULSION


Helicopter rotor blades are rotary wings. When

an engine turns the rotors, the blades generate

lift as they whirl through the air.


Special type of wings help them create lift. A

wing’s upper surface is curved and the lower is

flat. As the wings move, air flows over and

under the wing. The air flows faster over the

wing than under the wing. There is less

pressure on the upper surface than the lower.

The air is pushing more strongly at the bottom

thus creates the lift.

BLADE ELEMENT THEORY

In rotary-wing aircraft e.g. helicopters, induced

drag decreases with increased aircraft

airspeed


Angle of attack

- the amount of lift by changing the angle

that the wings make with the airflow.

TAIL ROTOR

Newton's third law of motion requires that for

every action there is an equal and opposite

action. A typical single main rotor helicopter

has a rotor system mounted on a rotor mast.

The helicopter engine supplies power so that

the helicopter can turn the mast. When the

helicopter applies torque to the mast to spin

it, there is an equal-and-opposite torque

reaction which tries to turn the helicopter in

the opposite direction.

Aircraft propulsion

Education