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P R A K S H E P An Exclusive Publication from Students of Department of Aeronautical Engineering,

FGIET

THE FIRST SUMMER SEMESTER EDITION

2013

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Prakshep An Exclusive Magazine from Department of Aeronautical Engineering, F G

Institute of Engineering & Technology

Year 1, Volume 1

Published on May 30, 2013

Chief Editors

Yajur Kumar

Megha Marwari

Technical Editors

Pankaj Mishra

Pankaj K Kushwaha

Creative Editor

Pushpa Kumari

Cover, Finance, Layout and Typesetting

Yajur Kumar

PUBLISHED BY

Students of Department of Aeronautical Engineering

F G Institute of Engineering & Technology, Rae Bareli 229001

ISBN 978-1-304-01467-2

Prakshep by Students of Department of Aeronautical Engineering, FGIET is

licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0

Unported License.

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A FEW WORDS FROM THE EDITOR

When the idea of regular magazine was suggested, I was in slight doubt if we will be able to

make it in time and in an interesting flavor. From telling the students to accepting the entries,

everything was a new experience, its being our first time handling a departmental publication

and my first time handling the overall editing.

Really big things starts from small things, I learnt it from somewhere, I exactly dont know,

but the words worth immense motivation in themselves. In my years at the college, I faced

several good things, several bad things too. Most of the times I planned starting a new

project, but everything went beyond my controls, either because of financial inabilities or

because I spent too much time in planning only. But, now when I look behind, I found there

were many reasons, the most important was working alone. A really big thing also needs a

really good team. So, in this project, which is however, a small step, we started with a good

team, who have, frankly speaking, no previous experience in this field of publication. But,

what we see later, that after a lot of clashes in views and opinions, we finally made it.

The magazine is intended at demonstrating the thoughts, creativity and imagination

capabilities of the students of the aeronautical engineering in the college. We have included

different sections for the purpose like concepts-which presents some of the hard concepts of

the aeronautical engineering, technology-a section on the latest technologies being

exploited in the aerospace field, curiosity-for those who likes to think out of the box, and

writing sections-a cluster of thoughts that came out on paper by the students, poetry and

other imaginative work. In addition, several other sections of importance are added.

However, I and we tried our best to present the things, it may be possible that we may

otherwise lack on a particular point. I personally ensures the reader that there is a good team

of coming fresher, sophomores and seniors, and they will present the publication in a more

interesting and curious ways in the future editions.

We warmly welcome any further ideas or suggestions to improve the quality of the

publication, for which you may write to Prakshep Magazine Publication Board, Department

of Aeronautical Engineering, F G Institute of Engineering and Technology, Rae Bareli.

Yajur Kumar

(Chief Editor)

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AKNOWLEDGEMENTS

I would like to thank the contributors for

contributing such smart articles and essays in a

very limited period of time, which made the

publication of the magazine possible on time. The

supporting editors deserves a special place,

Pankaj Kumar Kushwaha, Pushpa Kumari and

Pankaj Mishra, who helped us editing the technical

and creative work. Joint chief editor Megha

Marwari, who also worked hard late night like me,

deciding the flavor of the magazine and also

collaging the photo stuff, deserves a warm thanks.

Finally, thanks to our teacher, assist. Prof. N.

Srivastava the man behind the idea of the

magazine.

From my desk at 5 PM of May 1, 2013

YAJUR KUMAR

CHIEF EDITOR

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ONTENTS

Message from the Institutes Director

Message from the Head of the Department

A Few Words from the Editor

Acknowledgements

Concepts 1. The Rocket Principle 10 Yajur Kumar

2. Surface Control Devices 20 Megha Marwari

3. Thrust Vectoring 24 Nripendra K Singh

4. The Pulse Jet 26 Praveen K Singh

5. The Smart Materials 29 Akshay Gupta

6. Gliding Flight 32 Pankaj Mishra

7. Use of Blunt Shape in Reentry

Vehicles 33 Akshay Malik

8. Aircraft Propellers 35 Shraddha Singh

C

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9. Aircraft Flaps 38 Archana

10. NACA Airfoil Series 41 Pushpa Kumari

11. Do You Know? 44 Prof. R K Singh

12. All about Mach

number 47 Dimple Varshney

Technology 1. How a Satellite Works? 51 Yajur Kumar

2. What are Solar Flares? 56 P K Kushwaha

3. Electronic Warfare 58 Prof. A K Pandey

4. Green Aviation 60 P K Kushwaha

5. Introducing Stealth

Technology 63 Mayank Verma

6. The Traffic Collision

Avoidance System 68 Mayank Verma

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Curiosity 1. How to Find Them? 72 Yajur Kumar

2. Are We Alone in this

Universe? 77 Shiv Om

3. Boeing 787 Dreamliner 79 Megha Marwari

4. Flying High 83 Apoorva Mehrotra & Devanand Yadav

Poet among us 1. 87 Akshay Malik 2. 89 Archana

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Writer among us 1. Set Your Goals 92 Pushpa Kumari

2. Who is Responsible? 94 Namrata Saini

3. Brief History of Aviation 97 Pankaj Mishra

4. The Paper Airplane 100 Rateesh & Abhishek

AVIATION CAREERS 105 Megha Marwari | Yajur Kumar

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Concepts

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Chief Editor Yajur Kumar Final Year

Thanks to my three person smart team who assist me in the

designing of the whole magazine layout and also, thanks to the

random photographers whose contribution makes this magazine

colorful.

Connect with Yajur at fb.com/YajurK

___________________________________________________________________________

From flying a small rocket firework to

launching a giant cargo rocket to Mars, the

principles of how rockets work

are exactly the same. Understanding and

applying these principles means mission

success. Isaac Newton, born the year Galileo

died, advanced Galileos discoveries and

those of others by proposing three basic laws

of motion. These laws are the foundation of

all rocket science. This law simply points out

that an object at rest, such as a rocket on a

launch pad, needs the exertion of an

unbalanced force to cause it to lift off. The

amount of the thrust produced by the rocket

engines has to be greater than the force of

gravity holding it down. As long as the thrust

of the engines continues, the rocket

accelerates. When the rocket runs out of

propellant, the forces become unbalanced

again. This time, gravity takes over and causes

the rocket to fall back to Earth. Following its

landing, the rocket is at rest again, and the

forces are in balance.

1. Delta IV Medium Rocket

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There is one very interesting part of this law

that has enormous implications for

spaceflight. When a rocket reaches space,

atmospheric drag is greatly reduced or

eliminated. Within the atmosphere, drag is an

important unbalancing force. That force is

virtually absent in space. A rocket traveling

away from Earth at a speed greater than

11.186 kilometers per second will eventually

escape Earths gravity. It will slow down, but

Earths gravity will never slow it down enough

to cause it to fall back to Earth. Ultimately,

the rocket (actually its payload) will travel to

the stars. No additional rocket thrust will be

needed. Its inertia will cause it to continue to

travel outward. Four spacecraft are actually

doing that as you read this. Pioneers 10 and

11 and Voyagers 1 and 2 are on journeys to

the stars!

I am now going to explain the rocket

principle, in the easiest possible way. People

are usually very familiar with Newtons third

law. It is the principle of action and reaction.

In the case of rockets, the action is the force

produced by the expulsion of gas, smoke, and

flames from the nozzle end of a rocket

engine. The reaction force propels the rocket

in the opposite direction. When a rocket lifts

off, the combustion products from the

burning propellants accelerate rapidly out of

the engine. The rocket, on the other hand,

slowly accelerates skyward. It would appear

that something is wrong here if the action

and reaction are supposed to be equal. They

are equal, but the mass of the gas, smoke,

and flames being propelled by the engine is

much less than the mass of the rocket being

propelled in the opposite direction. Even

though the force is equal on both, the effects

are different. Newtons first law, the law of

inertia, explains why. The law states that it

takes a force to change the motion of an

object. The greater the mass, the greater the

force required to move it.

The second law relates force, acceleration,

and mass. The law is often written force

equals mass times acceleration. The force or

thrust produced by a rocket engine is directly

proportional to the mass of the gas and

particles produced by burning rocket

propellant times the acceleration of those

combustion products out the back of the

engine. This law only applies to what is

actually traveling out of the engine at the

moment and not the mass of the rocket

propellant contained in the rocket that will be

consumed later. The implication of this law

for rocketry is that the more propellant you

consume at any moment and the greater the

acceleration of the combustion products out

of the nozzle, the greater the thrust.

2. The Pioneer 10

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So far, so good. But, launching

rockets into space is more

complicated than Newtons laws

of motion imply. Designing

rockets that can actually lift off

Earth and reach orbital velocities

or interplanetary space is an

extremely complicated process.

Newtons laws are the

beginning, but many other

things come into play. For

example, air pressure plays an

important role while the rocket

is still in the atmosphere. The

internal pressure produced by

burning rocket propellants

inside the rocket engine

combustion chamber has to be

greater than the outside

pressure to escape through the

engine nozzle. In a sense, the

outside air is like a cork in the

engine. It takes some of the

pressure generated inside the

engine just to exceed the

ambient outside pressure.

Consequently, the velocity of

combustion products passing

through the opening or throat of

the nozzle is reduced. The good

news is that as the rocket climbs

into space, the ambient

pressure becomes less and less

as the atmosphere thins and the

engine thrust increases. Another

important factor is the changing

mass of the rocket. As the rocket

is gaining thrust as it accelerates

upward due to outside pressure

changes, it is also getting a boost

3. An engineering concept shows NASA's new heavy lift and crew launch vehicles.

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due to its changing mass. Every bit of rocket

propellant burned has mass. As the

combustion products are ejected by the

engine, the total mass of the vehicle lessens.

As it does its inertia, or resistance to change

in motion, becomes less. As a result, upward

acceleration of the rocket increases.

In real rocket science, many other things also

come into play. Even with a low acceleration,

the rocket will gain speed over time because

acceleration accumulates. And, not all rocket

propellants are alike. Some produce much

greater thrust than others because of their

burning rate and mass. It would seem obvious

that rocket scientists would always choose

the more energetic propellants. Not so. Each

choice a rocket scientist makes comes with a

cost. Liquid hydrogen and liquid oxygen are

very energetic when burned, but they both

have to be kept chilled to very low

temperatures. Furthermore, their mass is

low, and very big tanks are needed to contain

enough propellant to do the job.

Rocket science is a subject of immense

interest for aerospace engineers, and if you

are comfortable with getting crazy about

launching these real fireworks, there is a

rocket waiting to be launched at some place

by you in the very near future.

A Boeing 737 weighing 150,000 pounds (68,000 kg) must deflect about 88,000 pounds

(40,000 kg) of air - over a million cubic feet

(31,500 cubic meters) down by 55 feet (16.75

m) each second while in flight.

FACT FILE.

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Joint Chief Editor Megha Marwari Final Year

I find it very enjoyable to edit the different sections of the

magazine. Although it was a new task for us, but thanks to our

chief editor who helped organizing things in a delightful way.

Connect with Megha at fb.com/Megha.Marwari

Many of you like to solve crossword puzzles. So heres the one, all you have to do is to find the seven surface control and high lift devices. So lets begin!

Now let us have a brief knowledge about these control surface devices and high lift devices.

T R A I G Z S L O T S

E E X O F C Y T R S P

D L N T S E B I W A Y

U I E W F Q M R Z D N

V O X V L T V U O J O

W P D M A T J D K I R

N S F B P T F D U P E

K F S R S V O E L Y L

C O X L T G W R J R I

E M Z K A I M O Q T A

W A X J B T F L C Z R

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Ailerons are the control surfaces which are used to roll the aircraft. Two aileron control surfaces on each wing at the trailing edge and move opposite to each other generating the rolling moment and rolling the aircraft. A roll is positive if the aircraft rolls towards the pilots right. A roll is negative or negative roll when the aircraft rolls towards the pilots left.

Elevators are the control surfaces which are used for the pitching moment of the aircraft and are present at the trailing edge of the Horizontal tail or

horizontal stabilizer. An elevator role is to pitch the aircraft

i.e. (nose up or nose down). When elevator moves up, the aircraft nose moves up. When elevator moves down, the aircraft nose moves down.

Rudders are control surfaces which are used to yaw the aircraft. The rudders are present on the vertical tail or stabilizer and used to the yaw the aircraft in the required direction.

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Flaps are hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed at which an aircraft can be safely flown and to increase the angle of descent for landing. They shorten takeoff and landing distances. Flaps do this by lowering the stall speed and increasing the drag.

Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilize the boat or aircraft in a particular desired attitude without the need for the operator to constantly apply a control force. This is done by adjusting the angle of the tab relative to the larger surface.

Slats are aerodynamic surfaces on the leading edge of the wings of fixed-wing aircraft which, when deployed, allow the wing to operate at a higher angle of attack. A higher coefficient of lift is produced as a result of angle of attack and speed, so by deploying slats an aircraft can fly at slower speeds, or take off and land in shorter distances. They are usually used while landing or performing maneuvers which take the aircraft close to the stall, but are usually retracted in normal flight to minimize drag.

A leading edge slot is a fixed aerodynamic feature of the wing of some aircraft to reduce the stall speed and promote good low-speed handling qualities. A leading edge slot is a span-wise gap in each wing, allowing air to flow from below the wing to its upper surface. In this manner they allow flight at higher angles of attack and thus reduce the stall speed.

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ANSWERS

T R A I G Z S L O T S

E E X O F C Y T R S P

D L N T S E B I W A Y

U I E W F Q M R Z D N

V O X V L T V U O J O

W P D M A T J D K I R

N S F B P T F D U P E

K F S R S V O E L Y L

C O X L T G W R J R I

E M Z K A I M O Q T A

W A X J B T F L C Z R

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Nripendra K Singh Final Year I worked on my final year project of wind tunnel designing with my

team and find out that there is much more to explore in the field of

aviation than we know presently. Thanks to the editors for

presenting this magazine at its best. Connect with Nripendra at fb.com/Nripendra.Kr.Singh

You all must have

heard it or learned

this fact in your

course, that an

aircraft is controlled

and maneuvered by

using the Surface

controls viz.

Elevators, Ailerons,

Rudder and Trim

tabs. But these

controls are good

until we are talking

about general

purpose aircrafts

(such as

Passenger/Cargo

aircrafts), while

taking Fighter

aircrafts and

STOL/VSTOL

aircrafts under

considerations we

need some other

tool to control and

maneuver the

aircraft more faster and tightly during crucial

turns. This tool comes in the form of the

power produced by the Engine i.e. Thrust of

the Aircraft.

Thus, Thrust vectoring can be defined as the

technique of using the Engine thrust for the

purpose of controlling the Attitude of the

aircraft

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For applying the above mentioned

technique we use the movable nozzles.

These nozzles are specially designed, so as

to deviate the thrust producing hot mass of

gas from the turbine outlet in the desired

line of action. Nowadays, almost all of the

fighter aircrafts are using the technique of

Thrust vectoring. This is because when you

are operating under the situation of war or in

the battlefield(during Dog-Fights) then very

high maneuverability is required, as under

these conditions the pilot having less control

over its aircraft will be having a great

disadvantage.

A famous example of thrust vectoring is the

Lockheed Martin F-22 Raptor fifth-

generation jet fighter, with its afterburning,

thrust-vectoring Pratt & Whitney F119

turbofan.

Earlier, usage of this technology can be seen

in the Rolls-Royce Pegasus

engine used in the Hawker

Siddeley Harrier, as well as

in the AV-8B Harrier II

variant.

In India, The Sukhoi Su-30

MKI, produced under

license at Hindustan

Aeronautics Limited

employs 2 -Dimensional

thrust vectoring. The 2 -

Dimensional thrust

vectoring makes the

aircraft highly

maneuverable and capable

it to make high angles of

attack without stalling.

Thus, making Sukhoi Su-30

MKI as one of the best

fighter aircraft in active

service with the Indian Air

Force.

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4. F22 Raptor Thrust Vectoring

Praveen K Singh Final Year

I have been researching on various areas of Aircraft

Propulsion. I hope you will enjoy reading this article on

Pulsejet engines. Also, a warm thanks to my friend and Chief

Editor Yajur Kumar for presenting this magazine at its best. Connect with Praveen at fb.com/Praveen.Singh.100

The idea that the simplest engine an

engineer can make is a jet engine will sound

strange to most people -- we perceive jet

engines as big complex contraptions

pushing multi-million dollar aircraft through

the skies. Yet, this is completely true. In its

most basic form the pulsejet -- the jet

engine can be just an empty metal tube

shaped in a proper way.

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FACTS

The pulsejet engine was first invented in the early 1900 by a Swedish inventor Martin Wiberg.

Paul Schmidt, who engineered the first production pulsejet during the Second World

War with his flying bomb, the Argus V1.

Nicknamed the buzz bomb because of the low hum it admitted during flight.

Used by the Germans to bomb London from 1944-1945.

Over 9,000 V-1 were fired on England during WW2.

The pulsejet took a backseat in the engineering world when the turbofan jet engine was invented.

Has returned to the engineering scene as of late because of the interest in Pulse Detonation Engines.

WORKING PRINCIPLE

A pulsejet engine is a very simple jet engine

consisting of very little to no moving parts.

The combustion cycle comprises five or six

phases: Induction, Compression, (in some

engines) Fuel Injection, Ignition,

Combustion, and Exhaust.

The rapidly expanding gasses exit out of the

engine and as this happens a vacuum is

created in the combustion chamber which

pulls in a fresh new air charge from the

atmosphere, and then the whole cycle

repeats itself.

ADVANTAGE OF PULSE JET

The pulsejet is the only jet engine combustor

that shows a net pressure gain between the

intake and the exhaust. All the others have

to have their highest pressure created at the

intake end of the chamber. From that

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station on, the pressure falls off. Such a

decreasing pressure gradient serves to

prevent the hot gas generated in the

combustor from forcing its way out through

the intake. This way, the gas moves only

towards the exhaust nozzle in which

pressure is converted to speed. The great

intake pressure is usually provided by some

kind of compressor, which is a complex and

expensive bit of machinery and consumes a

great amount of power. Much of the energy

generated in the turbojet engine goes to

drive a compressor and only the remainder

provides thrust. The pulsejet is different.

Here, the exhaust pressure is higher than the

intake pressure. There is pressure gain

across the combustor, rather than loss.

Moreover, the pulsejet does it without

wasting the power generated by

combustion. This is very important.

WHY LOOK AT PULSEJETS NOW?

All the piston engines currently used in ultra-

light flying are relatively heavy and

cumbersome, even in their simplest form.

They also require much ancillary equipment,

like Redactors, prop shafts, propellers etc.

etc. Having all that gear mounted on a

lightweight flying machine almost defeats

the original purpose. A simple lightweight

pulsejet seems much more appropriate. The

enormous advances in computing power

over the past few decades have made

modelling of pulsating combustion more

realistic, too. It is still not easy even for the

supercomputers, but it can now be done.

This can cut down development time

drastically and make it much more

straightforward.

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Akshay Gupta Final Year

I have been researching over properties of smart materials.

Smart materials can enhance the entire aviation field, if

used suitably, so as I am presenting in this short article.

Thanks to the team of smart editors for presenting this

magazine in the best and most beautiful way. Connect with Akshay at fb.com/Aks.Gpt

Basically, there is no standard definition for

smart materials, and the term smart

material is generally defined as a material

that can change one or more of its properties

in response to an external stimulus. For

example, the shape of the material will

change in response to different temperature

or application of electrical charge or

presence of magnetic field. In general, it can

be catalogued to three main groups, which

are thermo to-mechanical, electrical-to-

mechanical and magnetic-to-mechanical. In

the other hand, there are some materials

which termed as smart material do not

have the properties stated above, like the

material with self-healing property is also

termed as smart material.

Therefore, smart material can also be

expressed as a material that can perform a

special action in response to some specific

condition such as very high/low

temperature, high stress, very high/low pH

value, even material failure, etc.

How are they significant in Aeronautical

applications?

Materials have a strong relationship with

aeronautical industry, as it always

determines the weight, strength, efficiency,

cost and difficulty of maintenance of an

aircraft.

Therefore, the discovery of new material

usually makes a breakthrough in

performance of an aircraft. Especially the

findings of smart materials, it makes an

innovation in aircraft because it can provide

a special function or property. Accordingly,

the smart materials receive a great attention

in order to improve the performance of

aircraft.

Categorization

Piezoelectric Materials

Figure 5: Monocrystal [Left] and Polycrystal [Right].

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Conducting Polymers

Shape Memory Alloys (SMAs)

Electrostrictive Ceramics

Magnetic Smart Materials

Fire Resistant Composites

Piezoelectric Materials

Basically, piezoelectric materials are

transducers between electricity and

mechanical stress. The piezoelectric

material has this effect because of its

crystallized structure. For the crystal, each

molecule has a polarization; it means one

end is more negatively charged while the

other end is more positively charged, and it

is called dipole. Furthermore, it directly

affects how the atoms make up the

molecule and how the molecules are

shaped. Therefore, the basic concept of

piezoelectricity is to change the orientation

of polarization of the molecules.

A Piezoelectric Material:

PZT [Lead Zironate Titanate]

Material Youngs Modulus, Gpa

Max actuator strain, m/m

Density, gm/cm3

PZT 50-70 0.12-0.18

7.6

Regarding the orientation of polar axis, the

crystal can be divided into two types which

are monocrystal and polycrystal.

The monocrystal means that all the

molecules polar axes are oriented in the

same direction, and the polycrystal means

that the polar axes of the molecules are

randomly oriented.

Application of Piezoelectric Material

Regarding the application of piezoelectric

material, there are two main functions

which are shape control and vibration

control.

Aerodynamic Feature

In term of shape changing, it means the

changing of aerodynamic feature.

Conventionally, the aircrafts control surface

is still controlled indirectly and lack of

flexibility. However, the piezoelectric

actuator can perform an innovative

mechanism of control system; it greatly

increases the performance and

maneuverability due to flexible, efficient

and thin actuator.

Vibration Control

Regarding vibration, it is an unwanted effect

in aircraft because it can contribute to stress

concentration, material fatigue, shortening

service life, efficiency reduction and noise.

Obviously, these problems influence the

safety and maintenance cost sharply.

Besides, the noise problem is always

considered, especially the passengers

aircraft, as the noise is a great annoyance.

Therefore, the engineers always want to

minimize the vibration. Conventionally, it is

difficult to provide a precise active damping

which produces a vibration with anti-

resonance frequency. By the piezoelectric

material, it can be used as sensor and

actuator at the same time, so it has a fast

enough response to produce the anti-

resonance vibration. Furthermore, it is

flexible, small and thin to be applied in many

parts of aircraft.

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Adaptive Smart Wing

Conventionally, the flap, rudder and

elevator are adjusted by electronic motor or

mechanical control system like cable or

hydraulic system. By applying piezoelectric

actuator, no discrete surfaces are required

because the control surface can be change

the sharp itself in order to change the

aerodynamic feature.

Therefore, it creates a continuous surface

which will not cause early airflow separation

hence to reduce the drag, but also the lift is

increased due to the delay airflow

separation. Accordingly, it increases the

efficiency significantly.

Basically, the concept of smart wing is to

construct a continuous control surface

embedded by a series of piezoelectric

actuator. Furthermore, it is required to have

a high strength-to-weight ratio; it means the

actuator has to be placed strategically for

optimizing a light weight design. Finally, it

should have an ability to change the shape

response to different flight condition, hence

the performance of cruise flight can be

improved that the conventional aircraft

cannot achieve. In fact, this concept has

started to be investigated since 2000.

However, the smart wing system is mainly

focus on military aircraft performance and

maneuver improvement. Since 2004, this

smart wing project has been started by

many industries and research centers such

as US Air

Force, NASA, Northrop Grumman and

Lockheed Martin. They constructed a 30%

scale Unmanned Combat Air Vehicle (UCAV)

at NASA Langley Research Centre. By two

wind tunnel testing, it showed that the

system had a high rate, large deflection,

conformal trailing edge control at realistic

flight conditions.

Helicopter Blade Application

For the improvement of helicopter, most of

engineers focus on the eliminating acoustic

problem because it is the major problem and

disadvantage. From the theoretical and

experimental work both in Europe and USA,

it shows that the BVI (Blade Vortex

Interaction, shown in Figure) is the main

source of noise, fortunately it can be

dramatically reduced, 8 to 10dB, by an

appropriate control of blades.

In order to solve this problem, there are two

possible solutions. The first solution is to

construct the blade that can perform a

continuous twisting. The second solution is

the servo-aerodynamic control surface like

flap, tab, or blade-tip is installed on the

blade

to generate aerodynamic force. Practically,

it is difficult to install any conventional

actuator in the blades of helicopter.

However, the piezoelectric actuator seems

to be suitable for the blades, so it receives an

extensive attention.

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Editor Pankaj Mishra Final Year

We worked really hard for presenting this magazine at its

best and I hope aero-students will surely enjoy exploring it.

Gliding Flight is

heavier than air

flight without use

of thrust. Gliders means sailplanes. Take an

airplane in a power off glide. The forces act

on this aircraft are lift drag and weight;

Thrust is zero due to power off. Glide flight

path makes angle below horizontal (means

without engine power).

For an equilibrium un-accelerated glide,

sum of the forces must be zero. Sum of

these forces along flight path

D = W Sin .. (i)

Perpendicular to flight path

L = W Cos (ii)

From (i)/ (ii)

Sin/cos = D/L

tan= 1/ (L/D)

Clearly, glide angle is a function of lift to

drag ratio. Higher the L/D, shallower the

glide angle. Smallest equilibrium glide

angle occurs at (L/D) max, which corresponds

to maximum range for glide.

Most common human application of gliding

flight is in sport and re-create using aircraft

design.

Gliding can be achieved with a flat (un-

cambered) wing as with simple paper plane.

IMPORTANCE OF GLIDE RATIO IN GLIDING

FLIGHT

Best Glide ratio is important to measuring

performance of gliding aircraft. Sometimes

fly aircrafts best L/D by controlling airspeed

and smooth operate to reduce drag. To

achieve higher speed, gliders loaded with

water ballast to increase airspeed which has

little effect on glide angle but increase rate

of shrink (speed over ground in proportion)

because the heavier aircraft achieve optimal

L/D at high airspeed.

BALLAST

Used in sailboats to provide moment to

resist lateral forces on sail.

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6. Glider.

Akshay Malik Pre-Final Year

Connect with Akshay at fb.com/Akshay.Malik.718

At the time of

reentry, near outer

edge of atmosphere, the reentry vehicle has

high velocity and as it is at high altitude, it

has large amount of potential energy. But

when the vehicle reaches to surface of earth,

it has relatively small velocity and nearly

zero potential energy. This large amount of

energy is lost due to following two reasons:

1. Heating the body of vehicle.

2. Heating the airflow around

vehicle.

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The shock wave formed at the nose of

vehicle heats the airflow around the vehicle

and at same time the vehicle is heated within

the boundary layer region due to intense

skin friction.

The temperature generated by such skin

friction is very high. We are required to make

less heating of the space craft. Because such

high temperature can damage the space

craft. The heat generated in this phenomena

will either heat vehicle body or air flow

around the body. If somehow we are able to

dissipate more heat into airflow than on

vehicle body, then our aim can be fulfilled.

This can be achieved by creating a stronger

shock wave at the nose of the reentry

vehicle.

If a slender body is used for reentry purposes

then weaker shock wave will be formed at

the nose of vehicle. It is shown by following

figure-Due to creation of weaker shock

waves the vehicle body will be heated more

than the surrounding airflow.

But if we use a blunt shape body then

stronger shock waves will be generated at

the nose of vehicle. As it can be seen clearly

with the help of following figure-

Thus by using the blunt shape body reentry

vehicle large heating of vehicle surface is

avoided.

This concept was first uncovered by Harvey

Allen in 1951.

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Shraddha Singh Pre-Final Year Connect with Shraddha at fb.com/ShraddhaSingh3014

Propeller is the

word which comes from the word propel

which means drive forward. Propeller is

used for providing thrust only. The engine

supplies brake horsepower through a

rotating shaft & the propeller converts it into

thrust horsepower.

=

Blade angle is the angle between the propellers plane of rotation, and the chord line of the propeller airfoil. Blade station is a reference position on a blade that is a specified distance from the center of the hub. Pitch is the distance (in inches or millimeters) that a propeller section will move forward in one revolution. Pitch distribution is the gradual twist in the propeller blade from shank to tip.

PROPELLER SLIP The distance this particular element would move forward in one revolution along a helix, or spiral, equal to its blade angle, is called Geometrical pitch. The Effective pitch is the actual distance a propeller advances through the air in one revolution. This cannot be determined by the pitch angle alone because it is affected by the forward velocity of the airplane. The difference between geometric and effective pitch is called propeller slip. Example- If a propeller has a pitch of 50 inches, in theory it should move forward 50 inches in one revolution. But if the aircraft actually moves forward only 35 inches in one revolution the effective pitch is 35 inches and the propeller efficiency is 70%.

Blade Angle & Angle of Attack

Blade angle is the angle between the propellers plane of rotation, and the chord line of the propeller airfoil.

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Angle of Attack is the angle between the chord line of an airfoil and the relative wind. When the airplane is at rest on the ground with the engine operating, or moving slowly at the beginning of takeoff, the propeller efficiency is very low because the propeller is restrained from advancing with sufficient speed to permit its fixed pitch blades to reach their full efficiency. In this situation, each propeller blade is turning through the air at an angle of attack which produces relatively little thrust for the amount of power required to turn it. To understand the action of a propeller, consider first its motion, which is both rotational and forward. Thus, as shown by the vectors of propeller forces, each section of a propeller blade moves downward and forward. The angle at which this air (relative wind) strikes the propeller blade is its angle of attack. The air deflection produced by this angle causes

the dynamic pressure at the engine side of the propeller blade to be greater than atmospheric, thus creating thrust. The shape of the blade also creates thrust, because it is cambered like the airfoil shape of a wing. Consequently, as the air flows past the propeller, the pressure on one side is less than that on the other. As in a wing, this produces a reaction force in the direction of the lesser pressure. In the case of a wing, the air flow over the wing has less pressure, and the force (lift) is upward. In the case of the propeller, which is mounted in a vertical

instead of a horizontal plane, the area of decreased pressure is in front of the propeller, and the force (thrust) is in a forward direction. Aerodynamically, then,

thrust is the result of the propeller shape and the angle of attack of the blade. Another way to consider thrust is in terms of the mass of air handled by the propeller. In these terms, thrust is equal to the mass of air handled, times the slipstream velocity, minus the velocity of the airplane. The power expended in producing thrust depends on the rate of air mass movement. On the average, thrust constitutes approximately 80% of the torque (total horsepower absorbed by the propeller). The other 20% is lost in friction and slippage. For any speed of rotation, the horsepower absorbed by the propeller balances the horsepower delivered by the engine. For any single revolution of the propeller, the amount of air handled depends on the blade angle, which determines how big a "bite" of air the propeller takes. Thus, the blade angle is an excellent means of adjusting the load on the propeller to control the engine RPM. The blade angle is also an excellent method of adjusting the angle of attack of the propeller. On constant speed propellers, the blade angle must be adjusted to provide the most efficient angle of attack at all engine

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and airplane speeds. Lift versus drag curves, which are drawn for propellers as well as wings, indicate that the most efficient angle of attack is a small one varying from 2 to 4 degrees positive. The actual blade angle necessary to maintain this small angle of attack varies with the forward speed of the airplane.

When relative airflow increases and airspeed remains constant then angle of attack also increases. When air speed increases and relative

airflow remains constant then angle of

attack decreases.

7. Hercules

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Archana Pre-Final Year

Flaps are hinged portion at trailing edge of

aircraft wing .Flaps are used to increase lift,

drag or both when deflected and used

principally for landing and take-off. The

higher the deflection of the flap is, the

greater the drag. It is like when your palm is

flat against the wind flow as you stretch your

hand out in a moving car. As you reduce the

angle against the airflow, the drag reduces

and you get better lift and your hand moves

up.

Flaps are used when the aircraft is slowing

down in preparation for a landing. In a plane,

flaps are usually used for both takeoff and

landing. They are partially extended before

takeoff to increase lift and reduce the

runway distance required to leave the

ground. They are fully extended during the

landing phase to allow the aircraft to safely

approach the runway at the lowest possible

speed.

Flap deflection of up to 15 primarily

produces lift with minimal drag. Deflection

beyond 15 produces a large increase in

drag. Drag from flap deflection is parasite

drag, and as such is proportional to the

square of the speed. Also, deflection beyond

15 produces a significant nose-up pitching

moment in most high wing airplanes

because the resulting downwash increases

the airflow over the horizontal tail.

Up/Down position of flaps during take off

It depends on the type of aircraft and the

circumstances of the takeoff. Aircraft

designed to cruise at high speedsincluding

most jet-powered aircraftmay extend

flaps slightly for takeoff because their low-

speed performance is limited by a design

that favors high-speed flight. A wing design

that provides a lot of lift at low speeds isn't

likely to be suitable for high speeds because

it will generate too much lift and too much

drag, but a wing design that works well at

high speeds may not generate a lot of lift at

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low speeds. So flaps are used to increase lift

for takeoff.

Low-speed aircraft, including small private

propeller-drive aircraft, can usually take off

without flaps, since they never fly at high

speed and their wings are designed to

generate plenty of lift at low speeds.

Flaps may also be extended (or extended

further) for takeoff from short runways,

again depending on the aircraft and the

exact circumstances. In any case, full

extension of the flaps is rare, as that often

generates more drag than it's worth.

Flaps during take-off position

Depending on the aircraft type, flaps may be

partially extended for takeoff. When used

during takeoff, flaps cover runway distance

for climb rateusing flaps reduces ground

roll and the climb rate. The amount of flap

used on takeoff is specific to each type of

aircraft.

Flaps during landing position

Flaps may be fully extended for landing to

give the aircraft a lower stalling speed so the

approach to landing can be made more

slowly or at low speed, which also allows the

aircraft to land in a shorter distance.

Types of flaps

There are basically main four types of flaps:

plain, split, fowler and slotted type

Plain flap: when this flap is deflected, it

changes (increases) both upper & lower

chamber of wing airfoil .This increase in

chamber leads to more lift at low speed and

low angle of attack. If flap is moved down

sufficiently, the drag increases significantly

and the lower surface become an effective

air-break.

Split edge flap: This type of flap is used

mostly in case of air beak where high drag is

required .when this flap is deflected upper

chamber remains same but lower chamber

increases which leads to more drag

.Deflected flap acts much like a spoiler,

producing lots of drag and little or no lift.

Fowler flap: Split flap slides backwards flat,

before deflecting downwards, thereby

increasing first chord, than camber. The flap

may act both like plain and split flap but it

must slide rearward before lowering.

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Slotted flap: In this type of flap there is

a gap between wing and flap which is

called slot and allows air from the

bottom of the wing to flow to the upper

portion of flap and downwards at

trailing edge of the wing .This delays

airflow separation and creates

downwards flow of air which produces

lift to the wing.

FACT FILE. A commercial aircraft door will not open in flight because it is actually bigger than the window

frame itself, and the door opens inwards towards the cabin. To open, it must be opened

inwards, rotated, and then slipped sideways out of the frame. Even if the door could somehow

be opened, it would be like lifting a 2,200 pound weight.

PRAKSHEP

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Editor Pushpa Kumari Final Year

To consider the creative editing was a very enjoyable experience. It

gives me a feeling that I am connected with the nature in an amazing

way. Thanks to our chief editors for presenting this magazine on time

and such a beautiful way.

Connect with Pushpa at fb.com/Pushpa.Kumari.96343

Airfoil structure is the basic of our

aeronautical world, but many times we are

not able to understand its dimensions to

know more about its parameter regarding

dimensions let see the AIRFOIL NACA

SERIES FAMILY.

NACA 4 DIGIT SERIES

The first digit specifies the maximum

camber (m) in percentage of the chord

(airfoil length). The second indicates the

position of the maximum camber (p) in

tenths of chord. The last two numbers

provide the maximum thickness (t) of the

airfoil in percentage of chord, e.g., NACA

2412

Maximum camber= .002c , position of

max camber = 0.04c, max thickness = .12c

NACA 5 DIGIT SERIES

The first digit, when multiplied by 3/2, yields

the design lift coefficient (cl) in tenths. The

next two digits, when divided by 2, give the

position of the maximum camber (p) in

tenths of chord. The final two digits again

indicate the maximum thickness (t) in

percentage of chord, e.g., NACA 23012

Lift coefficient = 0.3,

position of max camber = .15c,

max thickness = 0.12c

NACA 6 DIGIT SERIES

The first digit denotes the series and

indicates that this family is designed for

greater laminar flow than the Four- or Five-

Digit Series. The second digit is the location

of the minimum pressure in tenths of chord.

The subscript 1 indicates that low drag is

maintained at lift coefficients 0.1 above and

below the design lift coefficient (0.2)

specified by the first digit after the dash in

tenths. The final two digits specify the

thickness in percentage of chord, e.g., NACA

641-212,

The 6 denotes the series and indicates that

this family is designed for greater laminar

flow than the Four- or Five-Digit Series. The

second digit, 4, is the location of the

minimum pressure in tenths of chord (0.4c).

The subscript 1 indicates that low drag is

maintained at lift coefficients 0.1 above and

below the design lift coefficient (0.2)

specified by the first digit after the dash in

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tenths. The final two digits specify the

thickness in percentage of chord, 12%.

NACA 7 DIGIT SERIES

The 7-Series was a further attempt to

maximize the regions of laminar flow over

an airfoil differentiating the locations of the

minimum pressure on the

upper and lower surfaces, e.g., NACA

747A315.

The 7 denotes the series. The 4 provides the

location of the minimum pressure on the

upper surface in tenths of chord (40%). The

7 provides the location of the minimum

pressure on the lower surface in tenths of

chord (70%). The fourth character, a letter,

indicates the thickness distribution and

means line forms used. The fifth digit

indicates the design lift coefficient in tenths

(0.3). The final two integers are the airfoil

thickness in percentage of chord (15%).

NACA 8 DIGIT SERIES

A final variation on the 6- and 7-Series

methodology was the NACA 8-Series

designed for flight at supercritical speeds.

Like the earlier airfoils, the goal was to

maximize the extent of laminar flow on the

upper and lower surfaces independently.

The naming convention is very similar to the

7-Series, e.g., NACA 835A216.

The 8 designates the series. The 3 is the

location of minimum pressure on the upper

surface in tenths of chord (0.3c). The 5 is the

location of minimum pressure on the lower

surface in tenths of chord (50%). The letter A

distinguishes airfoils having different

camber or thickness forms, the 2 denotes

the design lift coefficient in tenths (0.2). The

16 provides the airfoil thickness in

percentage of chord (16%). Now we have a

brief description about all the NACA series.

We study above

FAMILY ADVANTAGE DISADVANTAGE APPLICATION

4- DIGIT 1. Good stall characteristics 2. Small center of pressure movement across large speed range 3. Roughness has little effect

1. Low maximum lift coefficient 2. Relatively high drag 3. High pitching moment

1. General aviation 2. Horizontal tails Symmetrical: 3. Supersonic jets 4. Helicopter blades 5. Shrouds 6. Missile/rocket fins

5-DIGIT 1. Higher maximum lift coefficient 2. Low pitching moment 3. Roughness has little effect

1. Poor stall behavior 2. Relatively high drag

1. General aviation 2. Piston-powered bombers, transports 3. Commuters 4. Business jets

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6-DIGIT 1. High maximum lift coefficient 2. Very low drag over a small range of operating conditions 3. Optimized for high speed

1. High drag outside of the optimum range of operating conditions 2. High pitching moment 3. Poor stall behavior 4. Very susceptible to roughness

1. Piston-powered fighters 2. Business jets 3. Jet trainers 4. Supersonic jets

7-DIGIT 1. Very low drag over a small range of operating conditions 2. Low pitching moment

1. Reduced maximum lift coefficient 2. High drag outside of the optimum range of operating conditions 3. Poor stall behavior 4. Very susceptible to roughness

Seldom used

8-DIGIT Unknown Unknown Very seldom used

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Assist. Prof. R K Singh Faculty Member

No one

knows who

discovered

the Jet

Propulsion

Principle, but

the favor is

sometimes

given to a

man named

Hero, who

lived in

Alexandria, Egypt, about 150 B.C.

One of the largest piston engine ever built, the R4360, 28 cylinder radial,

which develops 4,000 SHP, and the JT9D engine powering the Boeing 747.

If we use the

generally

accepted

conversion of

2.5 pounds of

thrust per SHP,

propeller static

thrust of R4360

would be

approximately

10000 lbs.,

neglecting

propeller

efficiency

losses. The

Boeing 747

8. The Jet Engine

9. R4360 Piston Engine

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would need 23 such engines to give the 230, 000 lbs. static thrust, currently

produced by its four JT9D turbofan engines.

The Pulsejet engine is fitted with inlet

shutters (flapper valves) to open and

close the air entering the engine. These

inlet shutters blew open and close

approximately 40 times per second to

allow and stop the air entering into the

engine.

Wright brothers incorporated first time

fuel injection system into a spark ignition

engine.

In a high by-pass ratio, turbofan engine

which has a by-pass ratio of 5:1, the by-

pass air produces 80% of the thrust and

10. JT9D Turbofan Engine of Boeing 747

11. The Pulse Jet Engine

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the core engine produces only 20% of the thrust. (By-pass ratio is the ratio

between the amount of air not entering the core engine (compressor,

combustion chamber, and turbine) or by passing the core engine and

amount of air entering the core engine.)

Assist. Prof. R. K. Singh, is a premier faculty member of

Department of Aeronautical Engineering. He served Indian

Navy as Chief Aircraft Maintenance Engineer for 15 years. He

teaches Aircraft Propulsion, maintenance and advanced

subjects like Rockets and Missiles at the institute.

PRAKSHEP

47

Dimple Varshney Final Year

The Mach number is commonly used

both with objects traveling at high

speed in a fluid, and with high-speed

fluid flows inside channels such

as nozzles, diffusers or wind tunnels. As

it is defined as a ratio of two speeds, it is

a dimensionless number. At Standard

Sea Level conditions (corresponding to

a temperature of 15 degrees Celsius),

the speed of sound is 340.3 m/s (1225

km/h, or 761.2 mph, or 661.5 knots, or

1116 ft./s) in the Earth's atmosphere.

The speed represented by Mach 1 is not

a constant; for example, it is mostly

dependent on temperature and

atmospheric composition and largely

independent of pressure. Since the

speed of sound increases as the

temperature increases, the actual speed

of an object traveling at Mach 1 will

depend on the fluid temperature

around it. Mach number is useful

because the fluid behaves in a similar

way at the same Mach number. So, an

aircraft traveling at Mach 1 at 20C or

68F, at sea level, will experience shock

waves in much the same manner as

when it is traveling at Mach 1 at 11,000

m (36,000 ft.) at 50C or 58F, even

though it is traveling at only 86% of its

speed at higher temperature like 20C

or 68F.

Classification of Mach regimes

While the terms "subsonic" and

"supersonic" in the purest verbal sense

refer to speeds below and above the

local speed of sound respectively,

aerodynamicists often use the same

terms to talk about particular ranges of

Mach values. This occurs because of the

presence of a "transonic regime" around

M=1 where approximations of

the Navier-Stokes equations used for

subsonic design actually no longer

apply, the simplest of many reasons

being that the flow locally begins to

exceed M=1 even when the free stream

Mach number is below this value.

Meanwhile, the "supersonic regime" is

usually used to talk about the set of

Mach numbers for which linearized

Regime Mach Mph km/h m/s

Subsonic 8,465

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theory may be used, where for example

the (air) flow is not chemically reacting,

and where heat-transfer between air

and vehicle may be reasonably

neglected in calculations.

In the following table, the "regimes" or

"ranges of Mach values" are referred to,

and not the "pure" meanings of the

words "subsonic" and "supersonic".

Generally, NASA defines "high"

hypersonic as any Mach number from

10 to 25, and re-entry speeds as

anything greater than Mach 25. Aircraft

operating in this regime include

the Space Shuttle and various space

planes in development.

High-speed flow around objects

Flight can be roughly classified in six

categories:

Regime

Subsonic

Transonic

Sonic

Supersonic

Hypersonic

High-hypersonic

Mach

10.0

For comparison: the required speed

for low Earth orbit is approximately 7.5

km/s = Mach 25.4 in air at high altitudes.

The speed of light in a vacuum

corresponds to a Mach number of

approximately 881,000 (relative to air at

sea level).

At transonic speeds, the flow field

around the object includes both sub-

and supersonic parts. The transonic

period begins when first zones of M>1

flow appear around the object. In case

of an airfoil (such as an aircraft's wing),

this typically happens above the wing.

Supersonic flow can decelerate back to

subsonic only in a normal shock; this

typically happens before the trailing

edge. (Fig.1a)

As the speed increases, the zone of M>1

flow increases towards both leading and

trailing edges. As M=1 is reached and

passed, the normal shock reaches the

trailing edge and becomes a weak

oblique shock: the flow decelerates over

the shock, but remains supersonic. A

normal shock is created ahead of the

object, and the only subsonic zone in

the flow field is a small area around the

object's leading edge. (Fig.1b)

(a)

(b)

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Fig. 1. Mach number in transonic

airflow around an airfoil; M1 (b).

When an aircraft exceeds Mach 1 (i.e.

the sound barrier) a large pressure

difference is created just in front of

the aircraft. This abrupt pressure

difference, called a shock wave, spreads

backward and outward from the aircraft

in a cone shape (a so-called Mach cone).

It is this shock wave that causes

the sonic boom heard as a fast moving

aircraft travels overhead. A person

inside the aircraft will not hear this. The

higher the speed, the more narrow the

cone; at just over M=1 it is hardly a cone

at all, but closer to a slightly concave

plane.

At fully supersonic speed, the shock

wave starts to take its cone shape and

flow is either completely supersonic, or

(in case of a blunt object), only a very

small subsonic flow area remains

between the object's nose and the

shock wave it creates ahead of itself. (In

the case of a sharp object, there is no air

between the nose and the shock wave:

the shock wave starts from the nose.)

As the Mach number increases, so does

the strength of the shock wave and the

Mach cone become increasingly

narrow. As the fluid flow crosses the

shock wave, its speed is reduced and

temperature, pressure, and density

increase. The stronger the shock,

greater the changes. At high enough

Mach numbers the temperature

increases so much over the shock that

ionization and dissociation of gas

molecules behind the shock wave

begin. Such flows are called hypersonic.

It is clear that any object traveling at

hypersonic speeds will likewise be

exposed to the same extreme

temperatures as the gas behind the

nose shock wave, and hence choice of

heat-resistant materials becomes

important.

FACT FILE... Most planes flying internationally have their home country's flag painted on or around

their tails. Generally, the flag is facing the proper way round on the left (port) side of

the aircraft, and backward on the starboard side. Why? Because that's how it would

look if a real flag were hoisted on a pole above the airplane during flight.

PRAKSHEP

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Technology

PRAKSHEP

51

Yajur Kumar Final Year

As per definition, satellite is basically

any object that revolves around a planet

in a circular or elliptical path. Well, in

this article, we are talking about

artificial or man-made satellites.

Satellites are an essential part of our

daily lives, from their use in weather

reports, television transmission and

everyday telephone calls. In many other

instances, satellites play a background

role that escapes our notice, such as

some newspapers and magazines are

timelier because they transmit their text

and images to multiple printing sites via

satellite to speed local distribution.

Your cellphones GPS device is also

functioning by the virtue of satellites.

Emergency radio beacons from downed

aircraft and distressed ships may reach

search-and-rescue teams when

satellites relay the signal.

The Soviet Sputnik

satellite was the first to

orbit Earth, launched

on Oct. 4, 1957.

Because of Soviet

government secrecy at

the time, no

photographs were

taken of this famous

launch. Sputnik was a

58 cm and 83 kg metal

ball. On the outside of

Sputnik, four whip

antennas transmitted

on short-wave

frequencies above and below what is

today's Citizens Band (27 MHz). After 92

days, gravity took over and Sputnik

burned in Earth's atmosphere. Thirty

days after the Sputnik launch, the dog

Laika orbited in a half-ton Sputnik

satellite with an air supply for the dog. It

burned in the atmosphere in April 1958.

Sputnik is a good example of just how

simple a satellite can be. As we will see

later, today's satellites are generally far

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more complicated, but the basic idea is

a straightforward one.

The path a satellite follows is an

orbit. In the orbit, the farthest

point from Earth is the apogee,

and the nearest point is the

perigee. All satellites today get

into orbit by riding on a rocket.

Many used to hitch a ride in the

cargo bay of the space shuttle.

Several countries and

businesses have rocket launch

capabilities, and satellites as

large as several tons make it

safely into orbit regularly.

For most satellite launches, the

scheduled launch rocket is

aimed straight up at first. This

gets the rocket through the thickest

part of the atmosphere most quickly

and best minimizes fuel consumption.

After a rocket launches straight up,

the rocket control mechanism uses

the inertial guidance system to

calculate necessary adjustments to

the rocket's nozzles to tilt the

rocket to the course described in

the flight plan. In most cases, the

flight plan calls for the rocket to

head east because Earth rotates to

the east, giving the launch vehicle a

free boost. The strength of this

boost depends on the rotational

velocity of Earth at the launch

location. The boost is greatest at

the equator, where the distance 12. The GPS Network

13. A drawing of the orbital path for the TRMM (Tropical Rainfall Measuring Mission) satellite

PRAKSHEP

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around Earth is greatest and so rotation

is fastest.

To make a rough estimate of boost from

an equatorial launch, we can determine

Earth's circumference by multiplying its

diameter by pi which gives, 40,065 Kms.

To travel around this circumference in

24 hours, a point on

Earth's surface has to

move at 1,669 Kmph.

A launch from Cape

Canaveral, Florida,

doesn't get as big a

boost from Earth's

rotational speed. The

Kennedy Space

Center's Launch

Complex 39-A, one of

its launch facilities, is

located at 28 degrees

36 minutes 29.7014

seconds north

latitude. The Earth's

rotational speed

there is about 1,440

Kmph. The difference

in Earth's surface

speed between the

equator and Kennedy

Space Center, then, is

about 229 Kmph.

Well, considering that

rockets can go

thousands of miles

per hour, you may

wonder why a

difference of only 229

Kmph would even

matter. The answer is that rockets,

together with their fuel and their

payloads, are very heavy. For example,

14. STS 11 Launching from Kennedy Space Center

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the Feb. 11, 2000, lift-off of the space

shuttle Endeavour with the Shuttle

Radar Topography Mission required

launching a total weight of 2,050,447

Kgs. It takes a huge amount of energy to

accelerate such a mass to 229 Kmph,

and therefore a significant amount of

fuel. Launching from the equator makes

a real difference.

Once the rocket reaches extremely thin

air, at about 193 Kms up, the rocket's

navigational system fires small rockets,

just enough to turn the launch vehicle

into a horizontal position. The satellite

is then released. At that point, rockets

are fired again to ensure some

separation between the launch vehicle

and the satellite itself.

A rocket must accelerate to at least

40,320 Kmph to completely escape

Earth's gravity and fly off into space.

Earth's escape velocity is much greater

than what's required to place an Earth

satellite in orbit. With satellites, the

object is not to

escape Earth's

gravity, but to

balance it.

Orbital velocity

is the velocity

needed to

achieve balance

between

gravity's pull on

the satellite and

the inertia of

the satellite's

motion -- the

satellite's

tendency to

keep going.

This is

approximately

27,359 Kmph at

an altitude of 242 Kms. Without gravity,

the satellite's inertia would carry it off

into space. Even with gravity, if the

intended satellite goes too fast, it will

eventually fly away. On the other hand,

if the satellite goes too slowly, gravity

will pull it back to Earth. At the correct

15. Schematic of a Rocket Motor

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orbital velocity, gravity exactly balances

the satellite's inertia, pulling down

toward Earth's center just enough to

keep the path of the satellite curving

like Earth's curved surface, rather than

flying off in a straight line.

Despite the significant differences

between the various kinds of satellites,

they have several things in common.

Such as:

all of them have a metal or

composite frame and body,

usually known as the bus. The

bus holds everything together

in space and provides enough

strength to survive the launch.

all of them have a source of

power (usually solar cells) and

batteries for storage. Arrays of

solar cells provide power to

charge rechargeable batteries.

Newer designs include the use

of fuel cells. Power on most

satellites is precious and very

limited. Nuclear power has

been used on space probes to

other planets (read this page

for details). Power systems are

constantly monitored, and

data on power and all other

onboard systems is sent to

Earth stations in the form of

telemetry signals.

all of them have an onboard

computer to control and

monitor the different systems.

all of them have a radio system

and antenna. At the very least,

most satellites have a radio

transmitter/receiver so that

the ground-control crew can

request status information

from the satellite and monitor

its health. Many satellites can

be controlled in various ways

from the ground to do

anything from change the orbit

to reprogram the computer

system.

all of them have an attitude

control system. The ACS keeps

the satellite pointed in the

right direction.

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Editor Pankaj K Kushwaha Final Year

Designing a whole new scientific publication needs hard work

and days of planning. I am heartily thankful to our chief editor

for managing things in such a precise way. Connect with Pankaj at fb.com/Pankaj.K.Kushwaha.9

A flare is defined as a sudden, rapid, and

intense variation in brightness. A solar flare

occurs when magnetic energy that has built

up in the solar atmosphere is suddenly

released. Radiation is emitted across the

entire electromagnetic spectrum, ranging

from radio waves to gamma rays. The

amount of energy released is the equivalent

of millions of 100-megaton hydrogen bombs

exploding at the same time! The first solar

flare recorded in writing was on September

1, 1859. Two scientists, Richard C.

Carrington and Richard Hodgson, were

independently observing sunspots at the

time, when they viewed a large flare in white

light.

As the magnetic energy is being released,

particles, including electrons, protons, and

heavy nuclei, are heated and accelerated in

the solar atmosphere. The energy released

during a flare is typically on the order of

10^14

Mega

joules per

second.

Large

flares can

emit up to

10^19

Mega

joules of

energy.

This

energy is

ten million

times

greater

than the

energy released from a volcanic explosion.

On the other hand, it is less than one-tenth

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of the total energy emitted by the Sun every

second.

There are typically three stages to a solar

flare. First is the precursor stage, where the

release of magnetic energy is triggered. Soft

x-ray emission is detected in this stage. In

the second or impulsive stage, protons and

electrons are accelerated to energies

exceeding 1 MeV. During the impulsive

stage, radio waves, hard x-rays, and gamma

rays are emitted. The gradual build up and

decay of soft x-rays can be detected in the

third, decay stage. The duration of these

stages can be as short as a few seconds or as

long as an hour.

Solar flares extend out to the layer of the

Sun called the corona. The corona is the

outermost atmosphere of the Sun,

consisting of highly rarefied gas. This gas

normally has a temperature of a few million

degrees Kelvin. Inside a flare, the

temperature typically reaches 10 or 20

million degrees Kelvin, and can be as high as

100 million degrees Kelvin. The corona is

visible in soft x-rays, as in the above image.

Notice that the corona is not uniformly

bright, but is concentrated around the solar

equator in loop-shaped features. These

bright loops are located within and connect

areas of strong magnetic field called active

regions. Sunspots are located within these

active regions. Solar flares occur in active

regions.

The frequency of flares coincides with the

Sun's eleven year cycle. When the solar cycle

is at a minimum, active regions are small and

rare and few solar flares are detected. These

increase in number as the Sun approaches

the maximum part of its cycle.

A person cannot view a solar flare by simply

staring at the Sun. Flares are in fact difficult

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to see against the bright emission from the

photosphere. Instead, specialized scientific

instruments are used to detect the radiation

signatures emitted during a flare. The radio

and optical emissions from flares can be

observed with telescopes on the Earth.

Energetic emissions such as x-rays and

gamma rays require telescopes located in

space, since these emissions do not

penetrate the Earth's atmosphere

Assist. Prof. A. K. Pandey Faculty Member

In the present age the electronics plays a

great role in our life, without it the globe is

devoid. The electronic warfare utilizes

electromagnetic spectrum from the low

frequencies to the high frequencies. Mainly

it is used in military operation which includes

electronic attacks, electronic support and

electronic fortification. By this this, we can

obtain tactical intelligence and surveillance

to achieve the war goal.

As the threats received from the intruder, it

reconfigures itself to counter threats. In

doing this, higher data bit rate technique are

incorporated to track the communication

system, also to intercept, identify and locate

the source of electromagnetic wave for the

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purpose of targeting enemy resources and

planning for the future war techniques.

Electronic warfare provides electronic

protection, which is used to protect man and

material from the intentional or

unintentional circumstances.

Electromagnetic radiation can be used to

degrade the combat capabilities, such as

misleading the weapon with the help of IR

rays emission, changing the transmission

frequency randomly which is known to our

forces, to deceive the enemy. The electronic

attack to devastate the enemy forces is

commonly used. In this process intense

electromagnetic waves are emitted which

can be used to block the wireless

communication which controls the radio

combat devices of the enemy.

Assist. Prof. A. K. Pandey, is a premier faculty member of

Department of Aeronautical Engineering. He served

different organizations in his brilliant career of serving the

nation. He teaches the Aircraft Instrumentation, Aircraft

Rules and advanced subjects like Avionics at the institute.

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Pankaj K Kushwaha Final Year

People around the world are switching to

skies in large numbers. In 2009, for the first

time in aviation history, Asia recorded more

air travelers than U.S., while U.S. airplanes

flew 704 million passengers, a number

forecast to reach 1.21 billion by 2020.

Catering such a humungous growth in

number of air travelers will require new

flights, more runways and airports .But

increment in all these will also have

repercussions which manifest it in the form

of engine emissions, unprecedented air

traffic, and nonstop noise and not to

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mention the unhappy citizens concerned

about their health and quality of life.

In order to reduce potential harm to the

environment and have a pleasant and

economical flight, NASA and other space

agencies are working in collaboration with

universities and industries to develop

environmentally beneficial, or "green,

aviation technologies. Green aviation means

aviation so in such a way to create least

possible disturbance in the environmental

balance.

GOALS FOR GREEN AVIATION

* to reduce aircraft fuel consumption.

* To reduce aircraft emissions.

* To reduce aircraft noise.

* To achieve the above three economically.

SOLUTIONS FOR GREEN AVIATION

Some of the above mentioned problem

could be dealt with improvement in

technologies and some with completely

revolutionary, innovative technologies.

1. The solution to reduction in fuel

consumption can be achieved by allowing

pilots to directly climb to their cruising

altitude or descend down at the touchdown

without levelling off frequently in order to

check for the traffic at the airport

2. A revolutionary satellite based air

transport communication system could be

installed with other avionics equipment to

allow fliers fly directly to their destination,

reducing 200 gallons of fuel every year.

3. Use of advanced lightweight composites

for aircraft body construction (e.g. Boeing

787 dream liner), increment of laminar flow

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over aircraft body which increases the lift is

to drag ratio.

4. Changes in engine design or operation

might include ultra-high bypass turbofans,

open rotor engines, use of alternative fuels

or locating engines on the body of the

aircraft in such a way that deflects engine

noise upward to keep it from reaching the

ground.

5. The last but not the least point to ponder

upon is research on development of

alternate fuel for the jet airliners. Amongst

all the available fuel alternatives algae

biomass has bagged the topmost position.

IT is not a food stock, scalable, has high

calorific value, easy to manufacture, works

well with existing infrastructure and meets

the fuel standard. Currently Boeing, GE,

P&W Airbus all are working on developing

biomass as an alternative fuel.

If the above mentioned points are

implemented then the earth would be a

better place to live in for sure with distances

which could be fathomed within a couple of

hours.

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Mayank Verma Pre-Final Year Connect with Mayank at fb.com/Er.Mayank2013

Stealth technology

also known as LOT

(Low Observability Technology) is a

technology which covers a range of

techniques used with aircraft, ships and

missiles, in order to make them less visible

(ideally invisible) to radar, infrared and other

detection methods.

In simple terms, stealth technology allows an

aircraft to be partially invisible to Radar or any

other means of detection. This doesn't allow

the aircraft to be fully invisible on radar.

Stealth technology cannot make the aircraft

invisible to enemy or friendly radar. All it can

do is to reduce the detection range or an

aircraft. This is similar to the camouflage

tactics used by soldiers in jungle warfare.

Unless the soldier comes near you, you can't

see him. Though this gives a clear and safe

striking distance for the aircraft, there is still

a threat from radar systems, which can detect

stealth aircraft.

STEALTH PRINCIPLE

The concept behind the stealth technology is

very simple. As a matter of fact it is totally the

principle of reflection and absorption that

makes aircraft "stealthy". Deflecting the

incoming radar waves into another direction

and thus reducing the number of waves does

this, which returns to the radar. Another

concept that is followed is to absorb the

incoming radar waves totally and to redirect

the absorbed electromagnetic energy in

another direction. Whatever may be the

method used, the level of stealth an aircraft

can achieve depends totally on the design

and the substance with which it is made of.

THE KEY FEATURES OF STEALTH

-Unusual Design

-Outer Paint

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-Reduce Heat Exhaust Signatures

-Eliminate High Altitude Contrails

-Eliminate Brown Exhaust

METHODS OF AVOIDING DETECTION

Design for stealth requires the integration of

many techniques and materials. The types of

stealth that a maximally stealthy aircraft &

ships seeks to achieve can be categorized as

visual, infrared, acoustic, and Radar.

VISUAL STEALTH

Low visibility is desirable for all military

aircraft and is essential for stealth aircraft. It

is achieved by coloring the aircraft so that it

tends to blend in with its environment. For

instance, reconnaissance planes designed to

operate at very high altitudes, where the sky

is black, are painted black. (Black is also a low

visibility color at night, at any altitude.)

Conventional daytime fighter aircraft are

painted a shade of blue known as "air-

superiority blue-gray," to blend in with the

sky. Stealth aircraft are flown at night for

maximum visual stealth, and so are painted

black or dark gray. Chameleon or "smart skin"

technology that would enable an aircraft to

change its appearance to mimic its

background is being researched

INFRARED STEALTH

Another important factor that influences the

stealth capability of an aircraft is the IR (i.e.

Infrared, electromagnetic waves in the. 72

1000 micron range of the spectrum)

signature given out by the plane. Usually

planes are visible in thermal imaging systems

because of the high temperature exhaust

they give out. This is a great disadvantage to

stealth aircraft as missiles also have IR

guidance system. The IR signatures of stealth

aircraft are minute when compared to the

signature of a conventional fighter or any

other Military aircraft.

Engines for stealth aircraft are specifically

built to have a very low IR signature. Another

main aspect that reduces the IR signature of

a stealth aircraft is to place the engines deep

into the fuselage. This is done in stealth

aircraft like the B-2, F-22 and the JSF. The IR

reduction scheme used in F-117 is very much

different from the others. The engines are

placed deep within the aircraft like any

Figure 17VISUAL STEALTH PLANE-HAWK

Figure 16 Thermal infrared image - US Military F117 Stealth

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stealth aircraft and at the outlet; a section of

the fuselage deflects the exhaust to another

direction. This is useful for deflecting the hot

exhaust gases in another direction.

Infrared radiation are emitted by all matter

above absolute zero; hot materials, such as

engine exhaust gases or wing surfaces heated

by friction with the air, emit more infrared

radiation than cooler materials. Heat-seeking

missiles and other weapons zero in on the

infrared glow of hot aircraft parts. Infrared

stealth, therefore, requires that aircraft parts

and emissions, particularly those associated

with engines, be kept as cool as possible.

ACOUSTIC STEALTH

Figure 18 Acoustic Stealth Aircraft

Although sound moves too slowly to be an

effective locating signal for antiaircraft

weapons, for low-altitude flying it is still best

to be inaudible to ground observers. Several

ultra-quiet, low-altitude reconnaissance

aircraft, such as Lockheed's QT-2 and YO-3A,

have been developed since the 1960s.

Aircraft of this type are ultra-light, run on

small internal combustion engines quieted by

silencer-suppressor mufflers, and are driven

by large, often wooden propellers. They make

about as much sound as gliders and have very

low infrared emissions as well because of

their low energy consumption. The U.S. F-117

stealth fighter, which is designed to fly at high

speed at very low altitudes, also incorporates

acoustic-stealth measures, including sound-

absorbent linings inside its engine intake and

exhaust cowlings.

RADAR STEALTH

Radar stealth or invisibility requires that a

craft absorbs incident radar pulses, actively

cancel them by emitting inverse waveforms,

deflect them away from receiving antennas,

or all of the above. Absorption and deflection

treated below are the most important

prerequisites of radar stealth.

AB SORPTION

Metallic surfaces reflect RADAR; therefore,

stealth aircraft parts must either be coated

with RADAR-absorbing materials or made out

of them to begin with. The latter is preferable

because an aircraft whose parts are

intrinsically RADAR-absorbing derives

aerodynamic as well as stealth function from

the