INDUSTRIAL TRAINING REPORT ON

“JET ENGINE”

Submitted in Partial Fulfillment for the award of the degree

Of

BACHELOR OF TECHNOLOGY

In

MECHANICAL ENGINEERING

By

Krishna Kanhaiya Reg.No:1021130162

DEPARTMENT OF MECHANICAL ENGINEERING SRM UNIVERSITY,NCR

CAMPUS,MODINAGAR-201204,GHAZIABAD,U.P

ACKNOWLEDGMENT

I acknowledge with profound gratitude, Mr. Rohit Sharma General

Manager(E&M) Jet Airways Delhi for providing the opportunity in getting

industrial training in this organization.

I am very greatly indebted and express our deep felt gratitude to Mr.Inderjit

Malik and Mr.B.B Singh Assistant Manager HR Department .

I Express my sincere thanks to Mr.Aniruddh Sahay.

I Specially Thanks to Mr.Dilpreet Singh (Foreman),for giving me his valuable time

and esteemed guidance during the entire training period.

Finally,I Would like to thank all those colleagues who help me out of intensifying

my technical knowledge and providing satisfactory solutions to my all queries.

INDEX

S.No Particulars

1. Abstract

2. Introduction

3. History of Jet Engines

4. Types of Jet Engine

5. Turboprop Engine

6. Turbofan

7. Turbojet Engine

8. Ramjet Engine

9. Turbines

10. Conclusion

11. References

ABSTRACT

The basic idea of the turbojet engine is simple. Air taken

in from an opening in the front of the engine is

compressed to 3 to 12 times its original pressure in

compressor. Fuel is added to the air and burned in a combustion chamber to raise the temperature of the fluid

mixture to about 1,100°F to 1,300° F. The resulting hot

air is passed through a turbine, which drives the

compressor. If the turbine and compressor are efficient,

the pressure at the turbine discharge will be nearly twice

the atmospheric pressure, and this excess pressure is

sent to the nozzle to produce a high-velocity stream of

gas which produces a thrust. Substantial increases in

thrust can be obtained by employing an afterburner. It is

a second combustion chamber positioned after the

turbine and before the nozzle. The afterburner increases

the temperature of the gas ahead of the nozzle. The

result of this increase in temperature is an increase of

about 40 percent in thrust at takeoff and a much larger percentage at high speeds once the plane is in the air.

INTRODUCTION

Jet Airways is the second largest Indian airline based

in Mumbai, Maharashtra, both, in terms of market share and

passengers carried. 51% of Jetairways owned by Naresh Goyal, and rest

of the ownership is unknown leading to SEBI's recent concerns of its

Merger with Etihad based on corporate laws. It operates over 1000

flights daily to 76 destinations worldwide. Its main hub is Mumbai, with

secondary hubs at Delhi, Kolkata, Chennai, Bengaluru and Pune. It has

an international hub at Brussels Airport, Belgium.

HISTORY OF JET ENGINE

The History of the Jet Engine Sir Isaac Newton in the 18th century was

the first to theorize that a rearward-channeled explosion could propel a

machine forward at a great rate of speed. This theory was based on his

third law of motion. As the hot air blasts backwards through then

Nozzle the plane moves forward .Henri Giffard built an airship which

was powered by the first aircraft engine, a three-horse power steam

engine. It was very heavy, too heavy to fly .In 1874, Felix de Temple,

built a monoplane that flew just a short hop down a hill with the help of

a coal fired steam engine .Otto Daimler, in the late 1800s invented the

first gasoline engine .In 1894, American Hiram Maxim tried to power his

triple biplane with two coal fired steam engines. It only flew for a few

seconds .The early steam engines were powered by heated coal and

were generally much too heavy for flight .American Samuel Langley

made a model airplanes that were powered by steam engines. In 1896,

he was successful in flying an unmanned airplane with a steam-

powered engine, called the Aerodrome. It flew about 1 mile before it

ran out of steam .He then tried to build a full sized plane, the

Aerodrome A, with a gas powered engine. In1903, it crashed

immediately after being launched from a house boat .In 1903, the

Wright Brothers flew, The Flyer, with a 12 horse power gas powered

engine .From 1903, the year of the Wright Brothers first flight, to the

late 1930s the gas powered reciprocating internal-combustion engine

with a propeller was the sole means used top Propel aircraft .It was

Frank Whittle, a British pilot, who designed the first turbo jet engine in

1930. The first Whittle engine successfully flew in April, 1937.

TYPES OF ENGINE

TAMJET

TURBOJET

TURBOFAN

TURBOPROP

TURBO FAN

The path the air takes through the engine and how power is produced

determines the type of engine. There are four types of aircraft turbine

engines—turbojet, turboprop, turbofan, and turboshaft.TurbojetThe

turbojet is the oldest kind of general-purpose airbreathing jet engine.

Two engineers, FrankWhittle in the United Kingdom and Hans von

Ohain in Germany, developed the concept independentlyinto practical

engines during the late 1930s.The turbojet engine consists of four

sections: compressor, combustion chamber, turbinesection, and

exhaust. The compressor section passes inlet air at a high rate of speed

to the combustion chamber. The combustion chamber contains the fuel

inlet and igniter for combustion. The expanding air drives a turbine,

which is connected by a shaft to the compressor, sustaining engine

operation. The accelerated exhaust gases from the engineprovide

thrust. This is a basic application of compressing air, igniting the fuel-air

mixture,producing power to self-sustain the engine operation, and

exhaust for propulsion .A turboprop engine is a turbine engine that

drives a propeller through a reduction gear. The exhaust gases drive a

power turbine connected by a shaft that drives the reduction

gearassembly. Reduction gearing is necessary in turboprop engines

because optimum propellerperformance is achieved at much slower

speeds than the engine’s operating rpm. Turboprop engines are a

compromise between turbojet engines and reciprocating power plants

.Turboprop engines are most efficient at speeds between 250 and 400

mph and altitudes between 18,000 and 30,000 feet. They also perform

well at the slow airspeeds required for takeoff and landing, and are fuel

efficiency.

Turboprop Schematic diagram showing the operation of a

turboprop engine An ATR-72, a typical turboprop aircraft .A turboprop

engine is a type of turbine engine which drives an aircraft propeller

using a reduction gear.[1]The gas turbine is designed specifically for this

application, with almost all of its output being used to drive the

propeller. The engines exhaust gases contain little energy compared to

a jet engine and play only a minor role in the propulsion of the

aircraft.[citationneeded]The propeller is coupled to the turbine through

a reduction gear that converts the high RPM ,low torque output to low

RPM, high torque. The propeller itself is normally a constant

speed(variable pitch) type similar to that used with larger reciprocating

aircraft engines.[citation needed]

Turboprop engines are generally used on small subsonic aircraft,

but some aircraft outfittedwith turboprops have cruising speeds in

excess of 500 kt (926 km/h, 575 mph).Large military and civil aircraft,

such as the Lockheed L-188 Electra and the Tupolev Tu-95,have also

used turboprop power. The Airbus A400M is powered by four

EuropropTP400 engines, which are the third most powerful turboprop

engines ever produced, afterthe Kuznetsov NK-12 and Progress D-

27.[citation needed]In its simplest form a turboprop consists of an

intake, compressor, combustor, turbine, anda propelling nozzle. Air is

drawn into the intake and compressed by the compressor. Fuel isthen

added to the compressed air in the combustor, where the fuel-air

mixturethen combusts. The hot combustion gases expand through the

turbine. Some of the power generated by the turbine is used to drive

the compressor. The rest is transmitted throughthe reduction gearing

to the propeller. Further expansion of the gases occurs in thepropelling

nozzle, where the gases exhaust to atmospheric pressure. The

propelling nozzleprovides a relatively small proportion of the thrust

generated by a turboprop.Turboprops are very efficient at flight speeds

below 450 mph because the jet velocity of thepropeller (and exhaust) is

relatively low. Due to the high price of turboprop engines, they

aremostly used where high-performance short-takeoff and landing

(STOL) capability andefficiency at modest flight speeds are required.

The most common application of turbopropengines in civilian aviation

is in small commuter aircraft, where their greater reliabilitythan

reciprocating engines offsets their higher initial cost. Turboprop

airliners now operateat near the same speed as small turbofan-

powered aircraft but burn two-thirds of the fuelper passenger.[2]

However, compared to a turbojet (which can fly at high altitude

forenhanced speed and fuel consumption) a propeller aircraft has a

much lower ceiling.Turboprop-powered aircraft have become popular

for bush airplanes such as the CessnaCaravan and Quest Kodiak as jet

fuel is easier to obtain in remote areas than is aviation-grade gasoline

(avgas).[citation needed][edit]Technological aspectsFlow past a

turboprop engine in operationMuch of the jet thrust in a turboprop is

sacrificed in favor of shaft power, which is obtainedby extracting

additional power (up to that necessary to drive the compressor) from

turbine

Expansion. While the power turbine may be integral with the gas

generator section, many turboprops today feature a free power turbine

on a separate coaxial shaft. This enables the propeller to rotate freely,

independent of compressor speed. Owing to the additional expansion

in the turbine system, the residual energy in the exhaust jet is low.

Consequently,the exhaust jet produces (typically) less than 10% of the

total thrust.[citation needed]Propellers are not efficient when the tips

reach or exceed supersonic speeds. For thisreason, a reduction gearbox

is placed in the drive line between the power turbine and thepropeller

to allow the turbine to operate at its most efficient speed while the

propeller operates at its most efficient speed. The gearbox is part of the

engine and contains theparts necessary to operate a constant speed

propeller. This differs from the turboshaft engines used in helicopters,

where the gearbox is remote from the engine.[citation needed]Residual

thrust on a turboshaft is avoided by further expansion in the turbine

system and/ortruncating and turning the exhaust 180 degrees, to

produce two opposing jets. Apart from the above, there is very little

difference between a turboprop and a turboshaft.[citation

needed]While most modern turbojet and turbofan engines use axial-

flow compressors, turbopropengines usually contain at least one stage

of centrifugal compression. Centrifugalcompressors have the advantage

of being simple and lightweight, at the expense of astreamlined

shape.[citation needed]Propellers lose efficiency as aircraft speed

increases, so turboprops are normally not usedon high-speed aircraft.

However, propfan engines, which are very similar to turbopropengines,

can cruise at flight speeds approaching Mach 0.75. To increase the

efficiency ofthe propellers, a mechanism can be used to alter the pitch,

thus adjusting the pitch to theairspeed. A variable pitch propeller, also

called a controllable pitch propeller, can also beused to generate

negative thrust while decelerating on the runway. Additionally, in the

eventof an engine outage, the pitch can be adjusted to a vaning pitch

(called feathering), thusminimizing the drag of the non-functioning

propeller.[citation needed]Some commercial aircraft with turboprop

engines include the Bombardier Dash 8, ATR42, ATR 72, BAe Jetstream

31, Embraer EMB 120 Brasilia, Fairchild SwearingenMetroliner, Saab

340 and 2000,Xian MA60, Xian MA600, and Xian MA700.[citation

needed][edit]

Turbofan The turbofan is a type of airbreathing jet engine that is

widely used for aircraft propulsion. The turbofan isbasically the

combination of two engines, the turbo portion which is a conventional

gas turbine [1]engine, and the fan, a propeller-like ducted fan. The

engine produces thrust through a combination ofthese two portions

working in concert; engines that use more jet thrust relative to fan

thrust are knownas low bypass turbofans, while those that have

considerably more fan thrust than jet are known as highbypass. Most

commercial aviation jet engines in use today are of the high-bypass

type, and most modernmilitary engines are low-bypass,The fan serves

two duties. Part of the airstream from the fan passes through the core,

providing oxygento burn fuel to create power. However, the rest of the

air flow bypasses the engine core and mixes withthe faster stream from

the core at the back of the engine. As engine noise is a function of

exhausttemperature, turbofan engines are significantly quieter than a

pure-jet of the same thrust. Additionally, theefficiency of propulsion is

a function of the relative airspeed of the exhaust to the surrounding

air;propellers are most efficient for low speed, pure jets for high

speeds, and ducted fans in the middle.Turbofans are thus the most

efficient engines in the range of speeds from about 500 to 1000 km/h,

the [2][3]speed at which most commercial aircraft operate. Turbofans

retain an efficiency edge over pure jets atlow supersonic speeds up to

roughlyMach 1.6, but have also been found to be efficient when used

withcontinuous afterburner at Mach 3 and above. However, the lower

exhaust speed also reduces thrust athigh vehicle speeds.The vast

majority of turbofans follow the same basic design with a large fan at

the front of the engine witha relatively small jet engine behind it. There

have been a number of variations on this theme, however,including

rear-mounted fans where they can be easily added to an existing pure-

jet design, or designsthat combine a low-pressure turbine and a fan

stage in a single rear-mounted unit

Turbofans were developed to combine some of the best features of

the turbojet and the turboprop. Turbofan engines are designed to

create additional thrust by diverting asecondary airflow around the

combustion chamber. The turbofan bypass air generates increased

thrust, cools the engine, and aids in exhaust noise suppression. This

provides turbojet-type cruise speed and lower fuel consumption.The

inlet air that passes through a turbofan engine is usually divided into

two separate streams of air. One stream passes through the engine

core, while a second stream by passes the engine core. It is this bypass

stream of air that is responsible for the term “bypassengine.” A

turbofan’s bypass ratio refers to the ratio of the mass airflow that

passes throughthe fan divided by the mass airflow that passes through

the engine core.TurboshaftThe fourth common type of jet engine is the

turboshaft. It delivers power to a shaft thatdrives something other than

a propeller. The biggest difference between a turbojet andturboshaft

engine is that on a turboshaft engine, most of the energy produced by

theexpanding gases is used to drive a turbine rather than produce

thrust. Many helicopters usea turboshaft gas turbine engine. In

addition, turboshaft engines are widely used as auxiliarypower units on

large aircraft.

Turboshaft engine is made up of two major parts assemblies: the

gas generator and the power section.The gas generator consists of

thecompressor, combustion chambers with ignitors and fuel nozzles,

andone or more stages of turbine. The power section consists of

additional stages of turbines, a gearreduction system, and the shaft

output. The gas generator creates the hot expanding gases to drive

thepower section. Depending on the design, the engine accessories

may be driven either by the gasgenerator or by the power section.In

most designs the gas generator and power section are mechanically

separate so that they may eachrotate at different speeds appropriate

for the conditions. This is referred to as a free power turbine. A

freepower turbine can be an extremely useful design feature for

vehicles, as it allows the design to forego theweight and cost of

complex multi-ratio transmissions and clutches.The general layout of a

turboshaft is similar to that of a turboprop. The main difference is that

a turbopropis structurally designed to support the loads created by a

rotating propeller, as the propeller is notattached to anything but the

engine itself. In contrast, turboshaft engines usually drive a

transmission which is not structurally attached to the engine. The

transmission is attached to the vehicle structure andsupports the loads

created instead of the engine. However, in practice many of the same

engines arebuilt in both turboprop and turboshaft versions, with only

minor differences .An unusual example of the turboshaft principle is

the Pratt & Whitney F135-PW-600 engine forthe STOVL F-35B - in

conventional mode it operates as a turbofan, but when powering the

Lift Fan and its witches partially to turboshaft mode to send power

forward through a shaft (like a turboprop) and partially to turbojet

mode to continue to send thrust to the rear nozzle.

Parts of a Jet Engine Fan - The fan is the first component in a

turbofan. The large spinning fan sucks in large quantities of air. Most

blades of the fan are made of titanium. It then speeds this air up and

splits it into two parts. One part continues through the "core" or center

of the jet engine, where it is acted upon by the other jet engine

components. The second part "bypasses" the core of the jet engine. It

goes through a ductthat surrounds the core to the back of the jet

engine where it produces much of the forcethat propels the airplane

forward. This cooler air helps to quiet the jet engine as well asadding

thrust to the jet engine.Compressor - The compressor is the first

component in the jet engine core.The compressor is made up of fans

with many blades and attached to a shaft.The compressor squeezes the

air that enters it into progressively smallerareas, resulting in an

increase in the air pressure. This results in an increase inthe energy

potential of the air. The squashed air is forced into the

combustionchamber.Combustor - In the combustor the air is mixed

with fuel and then ignited.There are as many as 20 nozzles to spray fuel

into the airstream. The mixture of air andfuel catches fire. This provides

a high temperature, high-energy airflow. The fuel burns withthe oxygen

in the compressed air, producing hot expanding gases. The inside of the

combustor is often made of ceramic materials to provide a heat-

resistant chamber. The heat can reach 2700°.Turbine - The high-energy

airflow coming out of the combustor goes into the turbine ,causing the

turbine blades to rotate. The turbines are linked by a shaft to turn the

blades inthe compressor and to spin the intake fan at the front. This

rotation takes some energyfrom the high-energy flow that is used to

drive the fan and the compressor. The gasesproduced in the

combustion chamber move through the turbine and spin its blades. The

Turbines of the jet spin around thousands of times. They are fixed

on shafts which haveseveral sets of ball-bearing in between

them.Nozzle - The nozzle is the exhaust duct of the jet engine. This is

the jet engine part whichactually produces the thrust for the plane. The

energy depleted airflow that passed theturbine, in addition to the

colder air that bypassed the engine core, produces a force whenexiting

the nozzle that acts to propel the engine, and therefore the airplane,

forward. Thecombination of the hot air and cold air are expelled and

produce an exhaust, which causes aforward thrust. The nozzle may be

preceded by a mixer, which combines the hightemperature air coming

from the jet engine core with the lower temperature air that

wasbypassed in the fan. The mixer helps to make the jet engine

quieter.HOW A JET ENGINE WORKSThis is a picture of how the air flows

through a jet engine.Jet engines move the airplane forward with a great

force that is produced by a tremendousthrust and causes the plane to

fly very fast.All jet engines, which are also called gas turbines, work on

the same principle. The enginesucks air in at the front with a fan. A

compressor raises the pressure of the air. Thecompressor is made up of

fans with many blades and attached to a shaft. The bladescompress the

air. The compressed air is then sprayed with fuel and an electric spark

lightsthe mixture. The burning gases expand and blast out through the

nozzle, at the back of theengine. As the jets of gas shoot backward, the

engine and the aircraft are thrust forward.The image above shows how

the air flows through the engine. The air goes through the coreof the

engine as well as around the core. This causes some of the air to be

very hot andsome to be cooler. The cooler air then mixes with the hot

air at the engine exit area.A jet engine operates on the application of

Sir Isaac Newtons third law of physics: for everyaction there is an equal

and opposite reaction. This is called thrust. This law isdemonstrated in

simple terms by releasing an inflated balloon and watching the

escaping airpropel the balloon in the opposite direction. In the basic

turbojet engine, air enters the frontintake and is compressed, then

forced into combustion chambers where fuel is sprayed intoit and the

mixture is ignited. Gases which form expand rapidly and are exhausted

throughthe rear of the combustion chambers. These gases exert equal

force in all directions,providing forward thrust as they escape to the

rear. As the gases leave the engine, theypass through a fan-like set of

blades (turbine) which rotates the turbine shaft. This shaft, inturn,

rotates the compressor, thereby bringing in a fresh supply of air

through the intake.Engine thrust may be increased by the addition of

an afterburner section in which extra fuelis sprayed into the exhausting

gases which burn to give the added thrust. At approximately

1400 mph, one pound of thrust equals one horsepower, but at higher

speeds this ratioincreases and a pound of thrust is greater than one

horsepower. At speeds of less than 400mph, this ratio decreases.In a

turboprop engine, the exhaust gases are also used to rotate a propeller

attached to theturbine shaft for increased fuel economy at lower

altitudes. A turbofan engine incorporates afan to produce additional

thrust, supplementing that created by the basic turbojet engine,for

greater efficiency at high altitudes. The advantages of jet engines over

piston enginesinclude lighter weight with greater power, simpler

construction and maintenance with fewermoving parts, and efficient

operation with cheaper fuelRAMJETA ramjet, sometimes referred to as

a stovepipe jet, or an athodyd, is a form of airbreathing jetengine using

the engines forward motion to compress incoming air, without a rotary

compressor. Ramjetscannot produce thrust at zero airspeed and thus

cannot move an aircraft from a standstill. Ramjetsrequire considerable

forward speed to operate well, and as a class work most efficiently at

speedsaround Mach 3. This type of jet can operate up to speeds of

Mach 6.Ramjets can be particularly useful in applications requiring a

small and simple engine for high speed use,such as missiles, while

weapon designers are looking to use ramjet technology in artillery

shells to giveadded range: it is anticipated that a 120-mm mortar shell,

if assisted by a ramjet, could attain a range of [1]22 mi (35 km). They

have also been used successfully, though not efficiently, as tip [2]jets

on helicopterrotors.Ramjets are frequently confused with pulsejets,

which use an intermittent combustion, but ramjets employa continuous

combustion process, and are a quite distinct type of jet engine.DESIGNA

ramjet is designed around its inlet. An object moving at high speed

through air generates a highpressure region in front and a low pressure

region to the rear. A ramjet uses this high pressure in front ofthe

engine to force air through the tube, where it is heated by combusting

some of it with fuel. It is thenpassed through a nozzle to accelerate it to

supersonic speeds. This acceleration gives the ramjetforward thrust.

A ramjet Engine is sometimes referred to as a flying stovepipe, a

very simple device comprising an air intake, acombustor, and a nozzle.

Normally the only moving parts are those within the turbopump, which

pumpsthe fuel to the combustor in a liquid-fuel ramjet. Solid-fuel

ramjets are even simpler.By way of contrast, a turbojet uses a gas

turbine driven fan to compress the air further. This gives

greatercompression and efficiency and far more power at low speeds,

where the ram effect is weak, but is alsomore complex, heavier and

expensive, and the temperature limits of the turbine section limit the

topspeed and thrust at high speed What is Thrust? Thrust is the

forward force that pushes the engine and, therefore, the

airplaneforward. Sir Isaac Newton discovered that for "every action

there is an equal andopposite reaction." An engine uses this principle.

The engine takes in a large volume ofair. The air is heated and

compressed and slowed down. The air is forced through manyspinning

blades. By mixing this air with jet fuel, the temperature of the air can be

as highas three thousand degrees. The power of the air is used to turn

the turbine. Finally,when the air leaves, it pushes backward out of the

engine. This causes the plane tomove forward. ROCKET ENGINE [1]A

rocket engine, or simply "rocket", is a jet engine that uses only

propellant mass for forming its highspeed propulsive jet. Rocket

engines are reaction engines and obtain thrust in accordance with

Newtonsthird law. Since they need no external material to form their

jet, rocket engines can be used forspacecraftpropulsion as well as

terrestrial uses, such as missiles. Most rocket engines are internal

combustionengines, although non combusting forms also exist.Rocket

engines as a group have the highest exhaust velocities, are by far the

lightest, but are the leastpropellant efficient of all types of jet

engines.Rocket engines produce thrust by the expulsion of a high-speed

fluid exhaust. This fluid is nearly alwaysa gas which is created by high

pressure (10-200 bar) combustion of solid or liquid propellants,

consistingof fuel and oxidiser components, within a combustion

chamber.

The fluid exhaust is then passed through a supersonic propelling

nozzle which uses heat energy of the gas to accelerate the exhaust to

very high speed, and the reaction to this pushes the engine in the

opposite direction .In rocket engines, high temperatures and pressures

are highly desirable for good performance as this permits a longer

nozzle to be fitted to the engine, which gives higher exhaust speeds, as

well as giving better thermodynamic efficiency .Uses of jet engines A

JT9D turbofan jet engine undergoing maintenance on a Boeing 747

aircraft Jet engines are usually used as aircraft engines for jet aircraft.

They are also used for cruisemissiles and unmanned aerial vehicles. In

the form of rocket engines they are used for fireworks, model rocketry,

spaceflight, andmilitary missiles.Jet engines have also been used to

propel high speed cars, particularly drag racers, with the all-timerecord

held by a rocket car. A turbofan powered carThrustSSC currently holds

the land speed record.Jet engine designs are frequently modified for

non-aircraft applications, as industrial gas turbines. Theseare used in

electrical power generation, for powering water, natural gas, or oil

pumps, and providingpropulsion for ships and locomotives. Industrial

gas turbines can create up to 50,000 shaft horsepower.Many of these

engines are derived from older military turbojets such as the Pratt &

Whitney J57 and J75models. There is also a derivative of the P&W JT8D

low-bypass turbofan that creates up to 35,000 HP.

CONCLUSION

Basically Industrial Training is Meant to express the individual to industrial atmosphere and also to

understand the basic structure and working principle of an organization.

This training apart from adding values towards particular knowledge has also helped in gaining practical

knowledge about working of various mechanical equipment .It also instructed us about the complex

activities and management rules involved in a larger organization .Thus the training program has added

impetus to both engineering knowledge and management skills which will definitely impact positively in

our carrier.

Bibilography

http://www.freepatentsonline.com Harris, William S.

http://www.freepatentsonline.com Jaeckel, Ernst (DE)

http:// www.google.com

http:// www.boeing.com

http:// www.jet engine.com