design of unmanned aerial combat vehicle

8/14/2019 DESIGN OF UNMANNED AERIAL COMBAT VEHICLE

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Design Of Unmanned Combat Aerial Vehicle

DESIGN OF UNMANNED COMBA AE!IA" VE#IC"E

A $!O%EC !E$O!

Submitted by

C#!ISO$#E! B#A!A#&M

D#INES# 'UMA!&U

in partial fulfillment for the award of the degree

of

BAC#E"O! OF ENGINEE!ING

in

AE!ONAUICA" ENGINEE!ING

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!A%A"A'S#MI ENGINEE!ING

CO""EGE(#ANDA"AM)*+,-+.

ANNA UNIVE!SI/00

C#ENNAI *++ +,.NOVEMBE! ,+-,

!A%A"A'S#MI ENGINEE!ING

CO""EGE

#ANDA"AM 1 *+, -+.

BONAFIDE CE!IFICAE

This is to certify that this is a bonafide record of work done by the student ,

,III year Aeronautical Engineering in the AIRCRAFT DESIG !R"#ECT $% &aboratory

during the acade'ic year ()%%$()%(.

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UNIVERSITY REGISTER No.


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Signat2re of Fac2lt3)in)Charge

S2bmitted for the $ractical E4amination held on 5555555555&&

Internal E4aminer E4ternal E4aminer

AC'NO6"EDGEMEN

*e would like to e+tend our heartfelt thanks to $rof& /ogesh '2mar Sinha for

giing us his able su--ort and encourage'ent. At this /uncture we 'ust e'-hasis

the -oint that this design -ro/ect would not hae been -ossible without the highly

infor'atie and aluable guidance of Mr& S2rendra Bogadi0Asst. !rofessor of

Aeronautical De-art'ent1, whose ast knowledge and e+-erience has greatly

hel-ed us in this -ro/ect. *e hae great -leasure in e+-ressing our sincere and

whole hearted gratitude to the'.

It is worth 'entioning about 'y friends and colleagues of the Aeronautical

de-art'ent for e+tending their kind hel- wheneer the necessity arose. I thank one

and all who hae directly or indirectly hel-ed us in 'aking this design.

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INDE7

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Serial no& Content $age no

%. Introduction

(. Data Fro' AD!$I

2. Ai' 3 "b/ectie

4. Three 5iew Diagra'

6. 5$n Diagra'

7. Gust Enelo-e

8. Schrenk9s Cure

:. &oad Esti'ation "n *ing

;.


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S/MBO"S AND NOAIONS USED

A.R. $ As-ect Ratio

= $ *ing S-an 0'1C $ Chord of the Airfoil 0'1

C $ ero &ift Drag Co$efficient

C-$ S-ecific fuel consu'-tion 0lbs?h-?hr1

C&$ &ift Co$efficient

D $ Drag 01E $ Endurance 0hr1

e $ "swald efficiency

& $ &ift 01

0&?D1 loiter $ &ift$to$drag ratio at loiter

0&?D1 cruise $ &ift$to$drag ratio at cruise

R $ Range 0k'1

Re $ Reynolds u'ber

S $ *ing Area 0'@1

Sref$ Reference surface area

Swet$ *etted surface area

Sa$ A--roach distance 0'1

Sf$ Flare Distance 0'1

Sfr$ Free roll Distance 0'1

Sg$ Ground roll Distance 0'1

Ttake$off $ Thrust at take$off 015cruise$ 5elocity at cruise 0'?s1

5stall $ 5elocity at stall 0'?s1

*e'-ty$ E'-ty weight of aircraft 0kg1

*fuel $ *eight of fuel 0kg1

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*-ayload$ !ayload of aircraft 0kg1

*) $ "erall weight of aircraft 0kg1

*?S $ *ing loading 0kg?'@1

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-&IN!ODUCION

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IN!ODUCION

The structural design of an air-lane actually begins with the flight enelo-e or 5$

n diagra', which clearly li'its the 'a+i'u' load factors that the air-lane can withstand at any-articular flight elocity. oweer in nor'al -ractice the air-lane 'ight e+-erience loads thatare 'uch higher than the design loads. So'e of the factors that lead to the structural oerload ofan air-lane are high gust elocities, sudden 'oe'ents of the controls, fatigue load in so'ecases, bird strikes or lightning strikes. So to add so'e inherent ability to withstand these rare butlarge loads, a safety factor of %.6 is -roided during the structural design.

The two 'a/or 'e'bers that need to be considered for the structural design of anair-lane are wings and the fuselage. As far as the wing design is concerned, the 'ost significantload is the bending load. So the -ri'ary load carrying 'e'ber in the wing structure is the s-ar0the front and rear s-ars1 whose cross section is an BI9 section. A-art fro' the s-ars to take thebending loads, suitable stringers need to take the shear loads acting on the wings.

nlike the wing, which is sub/ected to 'ainly unsy''etrical load, the fuselage is 'uchsi'-ler for structural analysis due to its sy''etrical crossing and sy''etrical loading. The'ain load in the case of fuselage is the shear load because the load acting on the wing istransferred to the fuselage skin in the for' of shear only. The structural design of both wing andfuselage begin with shear force and bending 'o'ent diagra's for the res-ectie 'e'bers. The'a+i'u' bending stress -roduced in each of the' is checked to be less than the yield stress ofthe 'aterial chosen for the res-ectie 'e'ber.

The Structural design inoles

Deter'ination of loads acting on aircraft

a1 5$n diagra' for the design studyb1 Gust and 'aneuerability enelo-es

c1 Schrenk9s Cure

d1 Critical loading -erfor'ance and final 5$n gra-h calculation

Deter'ination of loads acting on indiidual structures

a1 Structural design study Theory a--roach

b1 &oad esti'ation of wings

c1 &oad esti'ation of fuselage.

d1


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f1 Design of so'e co'-onents of wings, fuselage

DAA F!OM AD$)II


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Airfoil Thickness7J

Stall Angle:.6 deg

Ca'ber 6J

AIM 8 OB%ECIVE

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AIM 8 OB%ECIVE

The ob/ectie is to design the su-erior un'anned co'bat aerial ehicle and it has all kind

of wea-ons which satisfies the 'ission as well as 'ilitary reKuire'ents. This design entangles

with


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hree Vie9 Diagram

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O$ VIE6

F!ON VIE6

SIDE VIE6

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the structural 0'a+i'u' load factor1 and aerodyna'ic 0'a+i'u' C&1 boundaries for a

-articular flight condition.

This enelo-e de'onstrates the ariations of airs-eed ersus load factor 05 n1. In

another word, it de-icts the aircraft li'it load factor as a function of airs-eed. "ne of the -ri'aryreasons that this diagra' is highly i'-ortant is that, the 'a+i'u' load factorL that is e+tracted

fro' this gra-hL is a reference nu'ber in aircraft structural design. If the 'a+i'u' load factor is

under$calculated, the aircraft cannot withstand flight load safely. For this reason, it is

reco''ended to structural engineers to recalculate the 5$n diagra' on their own as a safety

factor.

!eal :al2es of load factor for se:eral aircraft

Fro' the table the li'it load factor for our CA5 ranges between

Mli'0Ne1 ;Mli'0$e1 2

First of all we need to find thea. Design


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Design


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Calc2lation Of he Negati:e C2r:e Of V)N Diagram0 Design


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0 0 0 0

25 0.65 25 -0.3253

30 0.9371 30 -0.4685

40 1.6659 40 -0.833

60 3.748 50.23 -1.31

87 7.88 175 -1.31

175 7.88 192.5 -1

192.5 6.88 192.5 6.88

The 5$n -lot is shown below, which clearly e+-lains the load factor behaior of the n'annedAerial 5ehicle

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This 5$n diagra' hel-s in -redicting the -ositie load li'it, negatie load li'it, !ositieaccelerated stall, negatie accelerated stall, s-eed li'it, Caution range, Safety li'it, structuralda'age, etc.,

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@& GUS ENVE"O$E

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Gust is a sudden, brief increase in the s-eed of the wind. Generally, winds are least gusty

oer large water surfaces and 'ost gusty oer rough land and near high buildings. *ith res-ect

to aircraft turbulence, a shar- change in wind s-eed relatie to the aircraftL a sudden increase in

airs-eed due to fluctuations in the airflow, resulting in increased structural stresses u-on the

aircraft.

Shar-$edged gust 0u1 is a wind gust that results in an instantaneous change in direction or

s-eed.

Deried gust elocity 0 or 'a+1 is the 'a+i'u' elocity of a shar-$edged gust that

would -roduce a gien acceleration on a -articular air-lane flown in leel flight at the design

cruising s-eed of the aircraft and at a gien air density. As a result a (6J increase is seen in liftfor a longitudinally disturbing gust.

The effect of turbulence gust is to -roduce a short ti'e change in the effectie angle of

attack. These changes -roduce a ariation in lift and thereby load factor

For elocities u- to 5'a+, cruise, a gust elocity of %6 '?s at sea leel is assu'ed. For

5di, a gust elocity of %) '?s is assu'ed.

Effectie gust elocity The ertical co'-onent of the elocity of a shar-$edged gust that

would -roduce a gien acceleration on a -articular air-lane flown in leel flight at the design

cruising s-eed of the aircraft and at a gien air density.

Reference Gust 5elocity 0ref1at sea leel %6'?s.

Design Gust 5elocity 0ds1 ref .

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Constructon

The increase in the load factor due to the gust can be calculated by

For cure aboe 5$a+is

*here ,

Gust Alleiation Factor.

'a+


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ct Chord at ti- < m

cr Chord at root ,&-.* m ; .&*

a9 lift cure slo-e for airfoil

Swee- angle at leading Edge of *ing

a ; +&+=

Therefore we obtain,

;@=&


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=y using the eKuations and for arious s-eeds of 'a+ we get the following gust lines

Calc2lation Of he $ositi:e And Negati:e C2r:e Of G2st Diagram0

V!"oct# $o%& '%ctor V!"oct# $o%& '%ctor

0 1 0 1

25 0.3125 25 0.3125

30 0.432 30 0.175

40 0.702 40 -0.1

60 1.894 50.23 -0.38

87 5.785 175 -3.81

192.5 3.156 192.5 -0.434

The load factors at the arious -oints can be found using the for'ula using the corres-onding

alues of 'a+and the gust enelo-e is found to be,

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&SC#!EN'S CU!VE

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SchrenHs C2r:e

&ift aries along the wing s-an due to the ariation in chord length, angle of attack and swee-

along the s-an. Schrenk9s cure defines this lift distribution oer the wing s-an of an aircraft,also called si'-ly as &ift Distribution Cure. Schrenk9s Cure is gien by

*here

y%is &inear 5ariation of lift along se'i wing s-an also na'ed as &%.

y(is Elli-tic &ift Distribution along the wing s-an also na'ed as &(.

a ;.

"inear "ift Distrib2tion0

"ift at root

"root;,@


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"ift intermediate

"-;--+,


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Ellitic "ift Distrib2tion0

Twice the area under the cure or line will gie the lift which will be reKuired to

oerco'e weight

Considering an elli-tic lift distribution we get

*here

b%is Actual lift at root

a is wing se'i s-an

&ift at ti-

b-;*


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Substituting different alues for + we can get the lift distribution for the wing se'i s-an

"ift distrib2tion table along semi san

4 linear ellitic Combined

+ 24:822 7:7;.84 %88:)%.4+&. 2%77)( 7:26.2)6 %7%8%:.8

- (:448% 782).;42 %467)%

-&. (6(24) 7662.2%4 %(;447.8

, (()(); 7(;7.((% %%2(6(.7

,&. %::)8: 6;4;.27; ;8)%2.7:

@ %66;48 64;6.8;( :)8(%.4@&. %(2:%7 4;)6.;87 7427).;;

;%7:6 4%(%.:44 48;)2.4(

&. 6;664 (;;4.46 2%(84.(2

. (84(2 ) %28%%.6

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.& "OAD ESIMAION ON 6ING

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The solution 'ethods which follow Euler9s bea' bending theory 0U?y


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/,>, ; *


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Self)6eight 3@0 Self)9eight of the 9ing(

**ing ).(6W *E'-ty

).(6W2)))W;.:%

66ing; =@.=&. N

6$ort; )@*=


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';)


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3,>, (7;88.4 (.%((

6ing 27:2 %.:86

F2el 2);2.72 %.;66

!eaction force and Bending moment calc2lations

VA; +5A$;42668.6$(7;88.4N27:2N2);2.72 )

VA; ?*@=.


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Shear Force0

=y using the corres-onding alues of + in a--ro-riate eKuations we get the -lot of shear force

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% (20 1

(BC Ay ySF y dx V += +

% (20 1 0 1

(DC A fuel

y ySF y dx V y dx

+= + +

% (20 1 2);4

(AD A

y ySF y dx V

+= + +

2( ( % (74(7( 24:822 %284 (6 (6sin ::.2 6

( 6 2

;7286:.(4

BC

x xSF x x x x x

= + + + +

((().;86 %:8:.2DC BCSF SF x x= +

((().;86 %:8:.2 2);2.72AD BCSF SF x x x= + +


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Bending moment

=y substituting the alues of + for the aboe eKuations of bending 'o'ents obtained we can get

a continuous bending 'o'ent cure for the -ort wing.

Note0if we re-lace the + by $+ in each ter' we get the distribution of starboard wing

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( )( )

2 ( %

(

4%.6

( 2 (

%)8%) %84277.6 7:8 (6 (6 sin6

28.6 (6 ::.2 %.77 %(.6 ;7286:.(4 ()%)%;4.4(%(

BC

xBM x x x x x

xx x x x

= + + +

+ + +

(% (

2(

BC A A

y yBM y V dx M

+ = + +

DC BC fuelBM BM y dx= +2 ((().;86 ;2;.%6DC BCBM BM x x= +

2);4AD DCBM BM x=


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Shear force and bending moment diagrams d2e to loads along chord9isedirection at cr2ise condition0

Aerod3namic center)This is a -oint on the chord of an airfoil section where the bending

'o'ent due to the co'-onents of resultant aerodyna'ic force 0&ift and Drag1 is constant

irres-ectie of the angle of attack. ence the forces are transferred to this -oint for obtaining

constant


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Co$efficient of 'o'ent about aerodyna'ic centre $).%6

&ocation of aerodyna'ic centre

4ac>c;+&,.

&ocation of shear centre

4sc>c;+&@

&ift and drag are the co'-onents of resultant aerodyna'ic force acting nor'al to and along the

direction of relatie wind res-ectiely. As a result, co'-onents of the' act in the chordwise

direction also which -roduce a bending 'o'ent about the nor'al 0V1 a+is.5

Co$efficient of force along the nor'al direction,

Cn;C"Cos JCD Sin

Cn 0).)6 W Cos $41 N 0).)%(6 W Sin $41

Cn).)6

Cc ;C"Sin JCD Cos

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Cc 0).)6 W Sin $41 N 0).)%(6 W Cos $41

Cc ).%(%(

Chord wise force at root,

FR 0).6W).%(%(W%.((6W%86(W:1

F!; -m

Chord wise force at inter'ediate length,

F- ; m

F,; ?+-&.. NKm

=y using y '+ Nc again we get the eKuation as

3 ; ),.*.&.4 J -.,-?

The aboe eKuation gies the -rofile of load acting chordwise, by integrating this aboe eKuation

we get a co'-onent of Shear force and again by integrating the sa'e we get the co'-onent of

=ending


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To find fi+ing 'o'ent and the reaction force,

VA ; +

VA ; +@?&@, N

MA; +

MA ;


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Bending Moment0

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(

2 (4(8.6: 87);.6 4)2;4.2( :27%7.(4

A ABM ydx V x M

BM x x x

= +

= + +


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TorKue due to nor'al forces and constant -itching 'o'ent at cruise condition

The lift and drag forces -roduce a 'o'ent on the surface of cross$section of the wing, otherwise

called a torKue, about the shear center.


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or2e at cr2ise condition0

or2e d2e to normal force0

*herec chordThe eKuation for chord can also be re-resented in ter's of + by taking c '+Nk

c ; )-&-,


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or2e d2e to chord 9ise force0

or2e d2e to moment0

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(

(

W )

)

cT F

T

=

=

( (

2

( (

2

(

2

2 (

2

%

(

).%6W ).6W%.((6W%86 W

(:%2.78

(:%2.78 ).4(4 8.66 44.:(

acMT C V c

T c

T cT x x x

=

=

= = +


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Then the different torKue co'-onents are brought together in a sa'e gra-h to 'ake aco'-arison

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The net torKue will be su' of all the aboe torKues i.e. torKue due to nor'al force, chordwise

force, -ower-lant and aerodyna'ic 'o'ent

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=& MAE!IA" SE"ECION

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Aircraft Metals

nowledge and understanding of the uses, strengths,li'itations, and other characteristics ofstructural'etals is ital to -ro-erly construct and 'aintain any eKui-'ent, es-ecially airfra'es.

In aircraft 'aintenance and re-air, een a slight deiation fro' design s-ecification, or the

substitution of inferior 'aterials,'ay result in the loss of both lies and eKui-'ent. The use of

unsuitable 'aterials can readily erase the finestcrafts'anshi-. The selection of the correct

'aterial fora s-ecific re-air /ob de'ands fa'iliarity with the 'ost co''on -hysical -ro-erties

of arious 'etals.

$roerties of Metals

"f -ri'ary concern in aircraft 'aintenance are suchgeneral -ro-erties of 'etals and their alloys

as hardness,'alleability, ductility, elasticity, toughness, density, brittleness, fusibility,

conductiity contractionand e+-ansion, and so forth. These ter's are e+-lainedto establish a

basis for further discussion of structural'etals.

#ardness

ardness refers to the ability of a 'aterial to resistabrasion, -enetration, cutting action, or

-er'anentdistortion. ardness 'ay be increased by cold working the 'etal and, in the case of

steel and certain alu'inu'alloys, by heat treat'ent. Structural -arts are often

for'ed fro' 'etals in their soft state and are then heattreated to harden the' so that the finished

sha-e will beretained. ardness and strength are closely associated -ro-erties of 'etals.

Strength

"ne of the 'ost i'-ortant -ro-erties of a 'aterial isstrength. Strength is the ability of a 'aterial

to resistdefor'ation. Strength is also the ability of a 'aterial to resist stress without breaking.

The ty-e of load orstress on the 'aterial affects the strength it e+hibits.

Densit3

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Density is the weight of a unit olu'e of a 'aterial.In aircraft work, the s-ecified weight of a

'aterial -ercubic inch is -referred since this figure can be used indeter'ining the weight of a

-art before actual 'anufacture.Density is an i'-ortant consideration whenchoosing a 'aterial to

be used in the design of a -artin order to 'aintain the -ro-er weight and balance ofthe aircraft.

Malleabilit3

A 'etal which can be ha''ered, rolled, or -ressedinto arious sha-es without cracking,

breaking, orleaing so'e other detri'ental effect, is said to be'alleable. This -ro-erty is

necessary in sheet 'etalthat is worked into cured sha-es, such as cowlings,fairings, or wingti-s.

Co--er is an e+a'-le of a 'alleable'etal.

D2ctilit3

Ductility is the -ro-erty of a 'etal which -er'its it tobe -er'anently drawn, bent, or twisted

into arioussha-es without breaking. This -ro-erty is essential for'etals used in 'aking wire

and tubing. Ductile 'etalsare greatly -referred for aircraft use because of theirease of for'ing

and resistance to failure under shockloads. For this reason, alu'inu' alloys are used for

cowl rings, fuselage and wing skin, and for'ed ore+truded -arts, such as ribs, s-ars, and

bulkheads.Chro'e 'olybdenu' steel is also easily for'ed intodesired sha-es. Ductility is

si'ilar to 'alleability.

Elasticit3

Elasticity is that -ro-erty that enables a 'etal to returnto its original siVe and sha-e when the

force whichcauses the change of sha-e is re'oed. This -ro-ertyis e+tre'ely aluable because it

would be highlyundesirable to hae a -art -er'anently distorted afteran a--lied load was

re'oed. Each 'etal has a -ointknown as the elastic li'it, beyond which it cannot be

loaded without causing -er'anent distortion. In aircraftconstruction, 'e'bers and -arts are so

designed that the 'a+i'u' loads to which they are sub/ected willnot stress the' beyond their

elastic li'its. This desirable-ro-erty is -resent in s-ring steel.

o2ghness

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A 'aterial which -ossesses toughness will withstandtearing or shearing and 'ay be stretched or

otherwisedefor'ed without breaking. Toughness is a desirable-ro-erty in aircraft 'etals.

Brittleness=rittleness is the -ro-erty of a 'etal which allows littlebending or defor'ation without

shattering. A brittle'etal is a-t to break or crack without change of sha-e.=ecause structural

'etals are often sub/ected to shockloads, brittleness is not a ery desirable -ro-erty. Cast

iron, cast alu'inu', and ery hard steel are e+a'-lesof brittle 'etals.

F2sibilit3

Fusibility is the ability of a 'etal to beco'e liKuid bythe a--lication of heat.


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tail s-ars is 'uch longer than their width and de-thL the ribs hae a 'uch larger chord length

than height and?or widthL a whole wing has a s-an that is larger than its chords or thicknessL and

the fuselage is 'uch longer than it is wide or high. Een a -ro-eller has a dia'eter 'uch larger

than its blade width and thickness, etc.... For this si'-le reason, a designer chooses to use

unidirectional 'aterial when designing for an efficient strength to weight structure.

nidirectional 'aterials are basically co'-osed of thin, relatiely fle+ible, long fibers which are

ery strong in tension 0like a thread, a ro-e, a stranded steel wire cable, etc.1

An aircraft structure is also ery close to asymmetrical structure. That 'eans the u- and

down loads is al'ost eKual to each other. The tail loads 'ay be down or u- de-ending on the

-ilot raising or di--ing the nose of the aircraft by -ulling or -ushing the -itch controlL the rudder

'ay be deflected to the right as well as to the left 0side loads on the fuselage1. The gusts hitting

the wing 'ay be -ositie or negatie, giing the u- or down loads which the occu-ante+-eriences by being -ushed down in the seat ... or hanging in the belt.

=ecause of these factors, the designer has to use a 84 structural 'aterial that can

withstand both tension and co'-ression. nidirectional fibers 'ay be e+cellent in tension, but

due to their s'all cross section, they hae ery little inertia 0we will e+-lain inertia another ti'e1

and cannot take 'uch co'-ression. They will esca-e the load by bucking away. As in the

illustration, you cannot load a string, or wire, or chain in co'-ression.

In order to 'ake thin fibers strong in co'-ression, they are Zglued togetherZ with so'e

kind of an Ze'beddingZ. In this way we can take adantage of their tension strength and are no

longer -enaliVed by their indiidual co'-ression weakness because, as a whole, they beco'e

co'-ression resistant as they hel- each other to not buckle away. The e'bedding is usually a

lighter, softer ZresinZ holding the fibers together and enabling the' to take the reKuired

co'-ression loads. This is a ery good structural 'aterial.

*+*- Al2mini2m Allo3

*+*-is a -reci-itation hardening alu'iniu' alloy, containing 'agnesiu' and silicon as its

'a/or alloying ele'ents. It has good 'echanical -ro-erties and e+hibits good weldability. It is

one of the 'ost co''on alloys of alu'iniu' for general -ur-ose use.

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It is co''only aailable in -re$te'-ered grades such as, 7)7%$" 0solutioniVed1, 7)7%$T7

0solutioniVed and artificially aged1, 7)7%$T76% 0eKuialent to T7 in rolled stock1.

Basic roerties

7)7% has a density of (.8) g?c'[ 0).);86 lb?in[1.

Chemical comosition

The alloy co'-osition of 7)7% is

Silicon 'ini'u' ).4J, 'a+i'u' ).:J by weight

Iron no 'ini'u', 'a+i'u' ).8J

Co--er 'ini'u' ).%6J, 'a+i'u' ).4)J


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b *+*-)

T4 te'-er 7)7% has an ulti'ate tensile strength of at least 2),))) -si 0()8

strength of at least %7,))) -si 0%%)

c *+*-)*

T7te'-er 7)7% has an ulti'ate tensile strength of at least 4(,))) -si 0(;)

strength of at least 26,))) -si 0(4%

elongation of :J or 'oreL in thicker sections, it has elongation of %)J. T76% te'-er has si'ilar

'echanical -ro-erties. The fa'ous !ioneer -laKue was 'ade of this -articular alloy.

Uses

7)7% is widely used for construction of aircraft structures, such as wings and fuselages, 'ore

co''only in ho'ebuilt aircraft than co''ercial or 'ilitary aircraft.

7)7% is used for yacht construction, including s'all utility boats.

7)7% is co''only used in the construction of bicycle fra'es and co'-onents.

6elding

7)7% is highly weldable, for e+a'-le using tungsten inert gas welding 0TIG1 or 'etal inert gaswelding 0


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Forgings

7)7% is also an alloy that is co''only used in a hot forging. The billet is heated through an

induction furnace and forged using a closed die -rocess. Auto'otie -arts, AT5 -arts, and

industrial -arts are /ust so'e of the uses as a forging.

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Sar design0

S-ars are 'e'bers which are basically used to carry the bending and shear loads acting

on the wing during flight. There are two s-ars, one located at %6$()J of the chord known as the

front s-ar, the other located at 7)$8)J of the chord known as the rear s-ar. So'e of the

functions of the s-ar include

They for' the boundary to the fuel tank located in the wing.

The s-ar flange takes u- the bending loads whereas the web carries the shear loads.

The rear s-ar -roides a 'eans of attaching the control surfaces on the wing.

Considering these functions, the locations of the front and rear s-ar are fi+ed at ).%8c and

).76c res-ectiely. The ARA$D 7J airfoil is drawn to scale using any design software and the

chord thickness at the front and rear s-ar locations are found to be 0).:4 ' and ).7( '1, 0).28 '

and ).2)1, 0).(28 ' and ).%66 ' 1 for three sections res-ectiely.

The s-ar design for the wing root has been taken because the 'a+i'u' bending 'o'ent

and shear force are at the root. It is assu'ed that the flanges take u- all the bending and the web

takes all the shear effect. The 'a+i'u' bending 'o'ent for high angle of attack condition is

()%)%;4.4( '. the ratio in which the s-ars take u- the bending 'o'ent is gien as

*here

h% height of front s-ar

h( height of rear s-ar

FI!S SECION

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The yield tensile stress Uyfor 7)7% Al Alloy is (87

=oth the flanges are connected by a ertical stiffener through s-ot welding

Fro' the buckling eKuation,

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the thickness to width ratio of web is found to be ).%)%7. Also fro' \AA&]SIS AD

DESIG "F F&IGT 5EIC&E STRCTRES by =R^, the flange to web width ratio of

the T section .

=y eKuating all the three alues of the ratio in area of the section eKuation, the di'ensions of the

s-ar can be found.

Secification For Front Sar0

t( %.)(7%7W%)$2

t ; +&+@,+ m

bf; +&,+=? m

b9; +&@-. m

Secification For !ear Sar0

t( 8.6862W%)$4

t ; +&+,=. m

bf; +&-=< m

b9; +&,=+ m

SECOND SECION



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*here

U is yield strength0(87


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t( (.%22W%)$2

t ; +&+*, m

bf; +&@+ m

b9; +&.= m


t( %.8%8W%)$2

t ; +&+- m

bf; +&,*? m

b9; +&+=. m

#I!D SECION



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Afs; +&+*,

Area of the rear s-ar

Ars; +&+.,

Ass2mtions0

T sections are chosen for to- and botto' flanges of front and rear s-ars.

=oth the flanges are connected by a ertical stiffener through s-ot welding

Fro' the buckling eKuation,

the thickness to width ratio of web is found to be ).%)%7. Also fro' \AA&]SIS AD

DESIG "F F&IGT 5EIC&E STRCTRES by =R^, the flange to web width ratio of

the T section .

=y eKuating all the three alues of the ratio in area of the section eKuation, the di'ensions of thes-ar can be found.

Secification For Front Sar0

t( 4.%%4:W%)$2

t ; +&+*, m

bf; +&-*m

b9; +&*@- m


t( (.7:(W%)$2

t ; +&+., m

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bf; +&@@. m

b9; +&.+< m

FI!S SECION

SECOND SECION

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CONC"USION

The structural design \-art (^ of the


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BIB"IOG!A$#/

%. Ray'er, D.!, Aircraft Design ) a Concet2al Aroach (AIAA educational series second

edition %;;(.

(. T..G.

design of unmanned aerial combat vehicle

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