What Are tWhat Are the Characteristics That Keep Solid and Fluid DifferentWhat Are the Characteristics That Keep Solid and Fluid DifferentWhat Are the Characteristics That Keep Solid

7/26/2019 What Are tWhat Are the Characteristics That Keep Solid and Fluid DifferentWhat Are the Characteristics That Keep

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What are the characteristics that keep solid and fluid

different?

When the force is applied tangentially on solid then it

experiences a finite deformation and shear stress that is

proportional to the deformation. Whereas, when the same shear

stress is applied on the surface of fluid then it experiences

continuous increasing deformation where, the shear stress is

proportional to the rate of change of deformation.

The fluid dynamic is dividend in three different areas. They

are as follows: Hydrodynamics flow of li!uids", #as dynamics

flow of gases" and $erodynamics flow of air". Whereas, thestate of, solid doesn%t represent any of the stages.

What are the o&'ectives of $erodynamics?

$erodynamics deals with the theory of flow of air and it has

many practical applications in engineering. There are some

o&'ectives that are &eing used in aerodynamics and these are

as follows:

(t is used to predict the forces, moments and heat transfer

from the &odies that is moving through the li!uid. (t deals with the movement of wings or use of the wind

force. This way it re!uires the calculations to &e done for

the aerodynamic heating of the flight vehicles and the

hydrodynamic forces applied on the surface of the vehicle.

(t is used to determine the flows that are moving internally

through ducts. This way it makes the calculations and

measurement of the flow properties that is inside the rocket

and 'et engines.

What are the sources involved in aerodynamics?

There are two sources that are involved in the case of

aerodynamics forces and moments that are on the &ody. These

forces are as follows:

)ressure distri&ution: this is the distri&ution that is over

the &ody surface

*hear stress distri&ution: this is the distri&ution that is

over the &ody surface

These sources are for the &ody shapes and it doesn%t matterhow complex they are. The mechanism that is &eing used to


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communicate with the &odies that is moving through a fluid.

+oth the pressure p" and shear stress ?" having the

dimension force per unit area. This helps the movement of the

&ody through the fluid.

What are the conditions given for the two flows to &e

dynamically similar?

To measure the dynamicity of the two flows consider two

different flow fields over two different &odies. This way the

conditions that get generated are as follows:

The streamlined pattern shouldn%t &e geometrically similar.

The distri&ution of the volume over change in volume -",

pressure over change in pressure p-p", and time over change

in time T-T". These changes take place throughout the flowof the field and they remain the same against the common non/

dimensional coordinates

The force coefficient remains the same.

There is a similarity in &oth the flows like the solid

&oundaries are geometrically similar for &oth flows.

What are the differences &etween continuum flow and free

molecule flow?

The flow that is moving over the &ody i.e. in a circularcylinder of diameter d is the continuum flow, whereas the flow

that consists of individual molecules moving in random motion

is the free molecule flow.

The mean free path ?" defines the mean distance &etween the

collisions of the molecule and if this path ?" is smaller

than the scale of the &ody measured d" then the flow of the

&ody is considered as continuum flow.

The path ?" that is of same order as the &ody scale then

the gas molecules then the &ody surface will have an impact of

the molecules and this is known as free molecular flow.

What are the differences &etween in viscid and viscous flow?

iscous flow is the flow in which the molecule moves in

random fashion and transfers their mass, momentum and energy

from one place to another in fluid. Whereas, an in viscid flow

is the flow in which there is no involvement of friction,

thermal conduction or diffusion while the molecules are

moving. (n viscid flow consists of the limited influence of


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friction, thermal conduction and diffusion that is limited to

thin region that is limited to the &ody surface. Whereas, the

viscous flows involve the flows that dominates the

aerodynamics of the &lunt &odies like cylinder. (n this the

flow expands around front face of cylinder and it separates

from the rear surface of it.

What are the differences &etween incompressi&le and

compressi&le flows?

(ncompressi&le flows are the flows that have a constant

density ?". Whereas, the compressi&le flows are those that

consists of varia&le densities.

The flows that exist are compressi&le in nature. Whereas,

incompressi&le flows, doesn0t exist in nature or are very

rare.

(ncompressi&le flows are used to model aerodynamic pro&lems

without losing any detrimental accuracy i.e. most pro&lems

that exist in hydrodynamics considers the density ?" 1

constant. Whereas, compressi&le flow is hardly used as a

mathematical model to, represent the hydrodynamics.

High speed flows are and must &e treated as compressi&le,

whereas incompressi&le flows are not considered for high speed

flows.

What are the different speed types of flows used in

identifying 2ach num&er?

There are four types of flows that consist of different speeds

and can &e identified using 2ach num&er:

*u&sonic flow where 234 everywhere, this is a field that is

defined as su&sonic if it matches the 2ach num&er that is less

than 4 at every point. These are displayed &y smooth

streamlines that consists of no discontinuity in slope. The

flow velocity is everywhere less than the speed of sound andthe distur&ances are all around the flow field.

Transonic flow, where mixed regions exist and 234 or 254,

this is a flow field that defines that the 2 is increased

'ust a&ove the unity and it is formed in front of the &ody.

These are the mixed su&sonic and supersonic flows that are

influenced &y &oth the flows.

*upersonic flow where 254 everywhere, this type is defined

when 2ach num&er is greater than 4 at every point. They are

represented &y the presence of shock waves across which the

flow properties and streamlines changes discontinuously.

Hypersonic flow where the speed is greater than supersonic,


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this is defined when the shock waves moves closer to the &ody

surface and the strength of the shockwave increases leading to

higher temperatures &etween the shock and &ody surface.

What are the ma'or sectors involved in aircraft maintenance?

There are two ma'or sectors involved in aircraft maintenance

and these are handled &y certifying technician in the field of

support and maintenance. These are divided into two sectors

as:

6ategory +4 mechanical": these are the maintenance

technicians that have good knowledge regarding the working of

airframe, engine, electrical power systems and e!uipment. (t

also re!uires additional knowledge of aircraft structures and

materials.

6ategory +7 avionic": this deals with the integrated

knowledge of aircraft e!uipment%s, electrical, instrument and

radar related systems. They undergo proper training to handle

the aircraft e!uipment%s and gain practical experience to deal

with day to day activities.

What are the operations performed &y 6ategory + technicians?

6ategory + consists of two sectors in the field of maintenance

and they are divided in +4 and +7 with certain roles. The

operations performed &y 6ategory + technicians are as follows:

$ctivities related to schedule on field inspections for

aircraft maintenance.

$ctivities of complex rectification

8ault diagnosis on aircraft systems and their e!uipment%s.

2odification and performing special instruction to monitor

and manage the system

9epairing of airframe and other aircrafts

$ctivities performed like removal of aircraft components and

fitting the re!uired parts. se of +(T; &uilt/in test e!uipment" and diagnostic

e!uipment%s to perform repair tasks.

*upervising and certifying the work of other technicians

involved in it.

What is the main source of power in aircraft?

The main source of power is the hydraulic motor that is

provided &y the scheduled service and involves operations that

allow technicians to solve complex system pro&lems. This setupre!uired certifying the technician to operate all the system


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the same way as it is &een done with one system. The hydraulic

motor needs to &e operated the same way and maintained in a

proper way. The alignment need to in synchroni


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6$$ 6ivil aviation authority" examines the applica&ility of

self/certification of aircraft engineering and verifies the

criticality of the tasks that need to &e performed on the

system. They also check the system for further services

without doing any functional checks.

9eview of the system takes place to interpret the single

components of the aircraft that is vital in its design.

9eviewing of the !uality assurance system and the reporting

methods take place to encourage more &etter designs to &e

provided for the use.

9eviewing the need to, introduce a format of 'o& description

and grades that is &eing provided to the engineers and

managers.

)roviding a mechanism for an independent assessment to carry

out the work audit and operations can &e performed smoothly.

What are the different stress types present in aircraft

operations?

*tress is a result that is caused when a solid e.g. metal &ar

is su&'ected to an external force. *tress is defined as force

per unit area and the &asic unit includes 2=-m7, =-mm7 and )a.

There are &asically three types of stress:

Tensile stress: it is the stress that is setup when the

force tries to pull the material apart. 6ompressive stress: it is the stress that is produced &y the

force that is trying to crush the material.

*hear stress: is the stress that results from the force that

tends to cut through the material i.e. tend to put one

material slide over another one.

Why is strain a ma'or factor in aircraft engineering?

*train is when a material is altered in shape, this happens

due to the fact that the force is acting on the material. The&ody is strained internally as well as externally without

having any differences of dimension &ut it 'ust has the

differences at the atomic level. (t is the ratio of change in

dimension over the original dimension. (t is very important

due to the fact that &uilding an aircraft re!uires the

knowledge of these factors and the formulas that are

associated with it to successfully implementing the parts

together. There are three types of strain:

Tensile strain

6ompressive strain and

*hear strain


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What are the different types of modulus involved in mechanics?

2odulus of elasticity is given &y the Hooke%s law that states

that stress is directly proportional to strain, while the

material remains elastic. The external forces that are acting

on the material is 'ust having the sufficient to stretch theatomic &onds this way the material can also return &ack to the

original shape. The different types of modulus are as follows:

2odulus of rigidity: this defines the relationship &etween

the shear stress t " and shear strain ? "

+ulk modulus: this defines that if a &ody volume v is

su&'ected to an increase in an external pressure then the

volume will &e changed &y d, this deformation will &e change

in volume not in shape.

What are the mechanical properties re!uired to know &efore

performing maintenance?

The mechanical properties provide the definition of the

&ehaviour of the material that is &eing put under the action

of external forces. This is an important aspect to

aeronautical engineering that is also used to gain knowledge

for applications developed for aircrafts. This provides an

overall view of the structure of the aircraft and the

maintenance aspect of it. The properties used are as follows:

*trength

*tiffness,

*pecific strength and stiffness,

>uctility,

Toughness,

2allea&ility and elasticity

;xplain in &rief a&out each property used in mechanics?

The properties of the mechanics are as follows:

*trength: this is the applied force on a material that can

withstand prior to fracture. (t is measured &y the proof or

yield stress of a material that is under action.

Working stress: this is the stress that is &eing imposed on

a material as a result of the load that is &eing su&'ected on

the material. The loads that are given must &e in the elastic

range.

)roof stress: defines the tensile stress

ltimate tensile stress T*": defines of a material that is

given &y a relationship or its maximum load. *pecific strength: defines the light and strong of a


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material that is used in aircraft making. This is done to

maximi


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down. The thrust force that is used for aircraft propulsion

should always come from air or gas pressure. The forces that

are external always act on the engine or propeller. This

propeller can &e driven either &y a piston or a gas tur&ine

engine. (f there is a use of 'et engine then the high velocity

exhaust gas is produced.

Why is the study of gyroscopes motion re!uired to learn

aircraft applications?

#yroscopic motion is considered as an important study for

aircraft application for the inertia and momentum of the &ody

that is used in circular motion. The momentum is the product

of the mass of a &ody and its velocity. This is a measure of

the !uantity of motion of a &ody. (nertia is the force that

doesn%t allow any change to happen in momentum. #yroscope is

the rotating mass that can &e moved freely at right angles to

its plane of rotation. This utili


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direction of the applied tor!ue. This also helps in finding

out the direction of the rotation of gyro/wheel. (f the tor!ue

is applied and is perpendicular to the spin axis then it can

&e transferred as a force.

What are the elements re!uired to display oscillatory motion?

The elements re!uired to display oscillatory motion are as

follows:

)eriod: this is related to the time and it signifies the time

that elapses in &etween the motion that will repeat itself

after some time again. @scillatory motions allow themselves to

&e repeated after e!ual intervals of time and this is called

as periodic.

6ycle: it represents the completion of one period and it

also signifies the motion that is completed in one period.

8re!uency: defines the num&er of cycles completed in unit

time.

$mplitude: defines the distance from one point to another or

from highest to lowest point of the motion from the central

position.

What are the different lift augmentation devices present?

ift augmentation devices provides flaps that are moving wing

sections that increase wing cam&er and provide an angel of

attack. 8laps have their own use like if an aircraft takes off

and land in a short distance then the wings of it should

produce sufficient lift at lower speed. 8laps provide a way to

slow down the aircraft. There two categories and they are as

follows:

Trailing edge flaps includes different flaps like

)lain flap that is used to retract the complete section of

trailing edge and it is used in downward.

*plit flap gets formed &y the hinged lower part of trailingedge and the lowered top surface remains unchanged and it

eliminates the airflow that occurs over the top of the surface

of the plain flap.

eading edge flaps: is used to augment the low speed lift

that is swept on the wing aircraft. They help in increase the

cam&er and allow the coupling to operate together with the

trailing edge flaps.

What are the steps re!uired to solve the pro&lems of aircraft

flying high and at very large speed?


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There are various steps re!uired to solve the pro&lems of

aircraft flying high and at very large speed are as follows:

+uild stiff wings that allow and provide the resistance to

torsional diversion &eyond the maximum speed of the aircraft.

se two sets of ailerons and one out&oard pair that can &e

operated at low speeds.

se of one in&oard pair that can &e used to operate on high

speeds, this will have less twisting impact when the ailerons

are positioned out&oard.

se spoilers that can &e positioned independently or can &e

paired with ailerons. These reduce the lift on the down going

wing &y interrupting the airflow over the top surface.

What are the functions performed &y rudder?

The rudder is involved in providing the movement to the ports

that gives a lift force to star&oard. This will allow the

aircraft to turn and uses the ailerons effectively to &ank the

aircraft &y minimum use of rudder. The functions performed &y

rudder are as follows:

(t is used with different applications that are involved in

taking off and landing to keep aircraft straight.

)roviding assistance that is, limited only for the aircraft

to turn correctly.

sed in applications during spin to reduce the roll rate ofthe aircraft and there are some applications that provides low

speeds and high angles to allow the raising of the wings.

What are the criteria need to &e followed for an aircraft to

&e longitudinal statically sta&le?

The criteria that are re!uired for an aircraft to &e

longitudinal statically sta&le, is:

To have a nose/down pitching distur&ance that is used to

produce the aerodynamics forces to give a nose/up restoringmoment.

This restoring moment that is produced should &e large

enough to return the aircraft to its original position after

the distur&ance.

The re!uirements are met &y using the tail/plain that is

hori


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A. What is ram 'et?

B. Why you would like to 'oin the aviation industry?

C. >oesn%t simplification of complex honeycom& designed for

thermal protection system of are usa&le launch vehicle

'eopardi


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operations, dynamics and controls?

7E. What is the testing done in aerospace engineering?

7. How would you handle if your co/worker is not co/operating

with you?

7F. What would you do if your 6aptain is not following the

instructions properly?

AG. When can one deviate from any flight rules and

regulations?

A4. When a pilot is assigned a speed, how much can one deviate

from that speed?

A7. Without $ir Traffic 6ontrol, what is the minimum descent

rate you can descend the plane?

AA. How would you handle the extreme pressure during emergency

situation if you know that plane is not safe and it might

crash anytime?AB. How important is to get the passengers switch off the

mo&ile phones and laptops during land off? What could &e the

conse!uences?

AC. How many types of emergency landings are there and

explain?

AD. What are the three tactical elements of electronic

warfare?

AE. What are the main areas in $viation?

A. What is the re!uirement to &ecome a )rofessional ;ngineer

);" in the field of $erospace?

AF. ;xplain the differences &etween $eronautical ;ngineering

and astronautical engineering?

BG. >oes the knowledge of mathematics of *cience is re!uired

to get into aerospace engineering?

B4. What do you understand &y $erodynamics-performance

analysis?

B7. What will &e the responsi&ility of the spacecraft

operations, dynamics, and controls?

BA. What would you do if your 6aptain were not following theinstructions properly?

BB. When can one deviate from any flight rules and

regulations?

BC. Without $ir Traffic 6ontrol, what is the minimum descent

rate you can descend the plane?

BD. ou are a&out to take off the plane in few seconds and a

catastrophic engine fails, and your captain tells you not to

take off and 'ust stay in the centre line. What would you do?

BE. How would you handle the extreme pressure during emergency

if you know that plane is not safe and it might crash anytime?


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B. What operational &enefits do hydraulic actuator-rate

controls have over gas charged units?

BF. How do ( decide which is the &est technology to solve my

vi&ration isolation pro&lem?

CG. What is isolation efficiency?

why aircraft body is made of aluminium and Why refrigeration

is done inside aircraft?

+ody of aircraft is made up of aluminium due to its good

tensile strength I good conductor. This is the com&ined effect

low pressure I speed of plane in sky.

What is ram jet?

$ ram'et, sometimes referred to as a stovepipe 'et, or an

athodyd, is a form of 'et engine with no moving parts. 9am'etscannot produce thrust at oes not simplification of complex honeycom& designed for

thermal protection system of are usa&le launch vehicles

'eopardi


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*)(6; is *imulation )rogram with (ntegrated 6ircuit ;mphasis.

This is analogy simulator which was developed at electronics

research la& of 6alifornia niversity.

&uelling and refuelling #recautions?$n hydraulic system' what stands for red and blue colours?

What are the main areas in A!iation?

$rtificial intelligence

$ircrafts and parts

$dvanced materials, composites and specialty metals

6omputers, electronic components and systems

8ighters and attack aircraft

#overnment defence policies and goals

asers

=avigation controls and guidance systems

@rdinance and 2ilitary vehicles

6omputers, electronic components and systems

$viation electronic-$vionics

9o&otics

*atellites

*earch and detection e!uipment%s

*trategic defensive initiative

*ensors and instrumentation

*hips

*pace vehicles and commerciali


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What made you choose aircraft maintenance

engineering(aerospace engineer line as your career?

(n aircraft maintenance(aerospace engineering there are lots

of interesting topics which include rocketry, aeroplanes,

ego%s. $s a school student ( started sketching for future

aircraft and space craft, military aircraft. ( analysed the

importance of space travel, aviation history, and aerospace

industry and hence decided to get into this field.

xplain the day to day responsibilities of Aerospace

engineering?

;ach 'o& profile even in aerospace industry differs from

others. To mainly speak a&out aerospace there are two &ranches

or field. @ne is aeronautical and other is astronautics

engineering.

xplain the differences between Aeronautical ngineering and

Astronautical ngineering

$eronautical engineering deals with vehicles which operates in

the atmosphere

$eronautical engineering deals with vehicles operating in

space.

$eronautical engineering works on tunnel tests, analysing

flight test data, manned space flights, planning future space

missions, spacecraft operations, designing and testing ro&otic

systems, developing new propulsion system, computing optimum

flight tra'ectories, developing communication systems for

distance space pro&es and designing new rockets.

$stronautical engineer includes designing power systems for

spacecraft structure, developing communications systems for

distant space pro&es, developing hardware skills for

operations in spacecraft, designing and testing ro&otic

systems, developing new propulsion systems and computing

optimum flight.

)oes the knowledge of mathematics of "cience is required to

get into maintenance engineering?

The &asic understanding of 2ath is important as it is not used

at all the time during the course of aerospace engineering.

@ne should have a &asic understanding of mathematical

definitions and knowledge on computers is very important as

the computer programs will help in doing simple calculations

and verify the results are reasona&le.

+ut on the science front it is very important to have a verygood understanding on various su&'ects like dynamics and


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mechanics in physics, strong emphasis on chemistry,

electromagnetism. 8or a good engineer one should know how law

of forces makes things happen.

$lso if you are good at physical sciences when opposed to lifesciences like &iology you will &e a fit candidate for

aerospace engineering.

*easons for why patch work are in round in shape?

+ow would you handle if your co,worker is not co,operating

with you?

Talk to your co/worker directly and explain him that you are

having a pro&lem working with him and make him understand the

situation, if he is not willing to listen or not co/operating,

then direct the issue to chief pilot.

What would you do if your %aptain is not following the

instructions properly?

9efer to your plane manual and discuss the same with your

client and ensure you make him understand the procedures and

rules. (f he does not respond, you will call your concerned

aircraft officer at the airport and escalate and make sure

your voice fre!uency is recorded.

Without Air -raffic %ontrol' what is the minimum descent rate

of the plane?

$ )ilot can descend up to CGGK &are minimum, without informing

the $T6 $ir Traffic 6ontroller" and this is only during an

exceptional cases. However, it%s always &etter to &e in

regular touch with the $ir Traffic 6ontroller and to keep him

informed a&out the descent rate. This will not have any

traffic pro&lems during landing in the runway.

What is +ard Landing? And mergency Landing?

+ow would you handle the extreme pressure during emergency

situation if you know that plane is not safe and it might

crash anytime?

8ew professions demand you to &e selfless, and our respective

clients would &e the most important thing, that is why

customer service differs completely in such fields compared to

other streams. 8or example, >octors, awyers, )ilotsLthese are

the professions where employee saving your customer is the up

most important thing.


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*o, as a engineer ( fully understand my duties and

responsi&ilities and will ensure that whatever panic situation

( could &e in, ( will continue to deliver my duties till the

end and ensure passengers are safe all times. *imultaneously (

will own the full responsi&ility of maintenance of $ir 6raft

safe and in the airworthy condition.

+ow many types of emergency landings are there and explain?

There are three types of emergency landings like:

8orced landing: This is a situation where $ir 6raft engine

fails and )ilot is forced to land the plane in the nearest

airport.

)recautionary landing: This is used when )ilot faces a

pro&lem due to severe weather conditions, or &eing lost in

the air space traffic or due to lack of fuel or expecting an

engine trou&le.

>itching: This is when where )ilot cannot avoid this situation

&ut to 'ust land on water, which is safer than air &ound.

.ou are a &light ngineer? +ow important is to get the

passengers switch off the mobile phones and laptops during

land off? What could be the consequences?

(t is very important to check if laptop and mo&ile phones are

switched off or not, as the conse!uences can &e &adL.&ecauseinterference of air crafts communication devices and

electronic devices interfere with each other and there could

&e chances of not proper landing.

*o, it%s highly recommended that all electronic and

communication devices should &e

switched off during take/off and landing.

What interests and abilities would help me as an Aircraft

Maintenance ngineering(Aerospace engineer?

*uccessful aerospace engineers need lots of curiosity, pro&lem

solving skills, organi


19/19

#ood pay, good promotion potential, travel, respect from the

community at large, and you get to say that you are a man with

rocket scienceN

What are the disad!antages of being in aerospace industry?The &iggest disadvantage is that it is a relatively small

field, and the num&er of companies in the field is getting

smaller lots of mergers &etween &ig companies in the news

lately".

Aircraft Maintenance ngineering&ut now foreign companies are catching upM this means that

$merican companies are streamlining their organi

Documents

What Are tWhat Are the Characteristics That Keep Solid and Fluid DifferentWhat Are the Characteristics That Keep Solid and Fluid DifferentWhat Are the Characteristics That Keep Solid