Paer Ist Exame 1 Dec10 2012

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PROJECTO AEROESPACIAL

TESTE Dezembro 10, 2012

Student Name/No:______________Group No. ______________ Marks: _____/100

A.DESIGNPROJECT [15MARKS]

1.Intwopageswithsketches,describethegoalofyourdesignproject,thevariousconcepts

youhavegeneratedandtherationalethatyouusedtoselectyourfinaldesign.Inparticular,

discusstheelectricpropulsionfeasibilitystudythatyourgroupperformed[15]

B.INITIALSIZINGANDPERFORMANCE [45MARKS]

1.Designobjective:Youareaskedtodesignanemergencysupplycargoplane.Theaircraft

hasapilotandco-pilot,andiscapableofcarrying1500lbsofpayload.Theaircraftshouldbe

capableofarangeof2000nm,flyingat40,000ftataMcruiseof0.75beforereleasing1500lbsof the expendable emergency payload.The aircraft then cruises back at the same altitude

allowingforamaximumceilingof45,000ftforeitherlegofthecruise.Themainwingofthe

aircrafthasanaspectratioof9,aC LMaxof1.7(cleanconfiguration)andtheminimumstall

speedimposedtothisaircraftatsealevelis95kts.

e(OswaldCoefficient)=0.8 1kg=2.2046lb

1kts=1.8Km/h μ=0.0000107lbm/(f-s)

(a)Drawthemissionprofile[5]

(b)Estimate theMaximumTakeOffWeight (MTOW).AssumeMTOW=10,000lbs for yourfirstiterationandperform2iterations.[10]

(c)Define the feasibleportion for the design spacefor your configurationbyshading the

infeasibleregionoftheT/WvsW/Splot.UsetheconstraintsforV stall,ClimbGradient(use

theclimbangleconstraintgiveninclass!

!≥ sin + 2 !!)andVcruise(usetheCruise

Speedconditionpresentedinclass:( )

⎟⎠

⎞⎜⎝

⎛+≥

S

W

V

K 2

SW2

CV

W

T

2

D

2

0

ρ

ρ )[10]

(d)Assumethattheaircraftistobedesignedforlowobservabilityforoperationinsensitive

areas.Assumethattheobservabilityoftheaircraftisafunctionofthesizeoftheaircraft(radarsignature)andthethrustrequired(moreheatmeanseasiertoobserve).Ifsomeone

toldyouthattheobservabilitywasgivenbythefollowingrelationship,determinethebest

T/WandW/Sforyourstealthsupplyaircraft.[10]

∝ −0.02!

!+

!

!+ 0.5(ImperialUnits)

(e)Calculatethewingspan,meanaerodynamicchord,assumethecorrectvaluesforsweep,

t/candtaperratioandcalculatethefunctionofthewingpolarforthepresentaircraftwing

atcruise conditions. (assumeairfoil has aClmax=1.03,!!= 0.12 perdegree and !!!"# =

−1.5degrees)[10]



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C–ENGINE/PROPELLERDESIGN [20MARKS]

1. Athreebladedpropellerhasbeenchosentopowerahighlyefficientsingleseateraircraftdesign,developedforlowaltitudeflightandforacruisevelocityof40m/s(motorglider

type).Thepropellerhasadiameterof1.2m(nogearboxisusedinbetweenthemotorand

propeller) with cruise being performed at an optimum motor speed of 2000 rpm.

Determine the characteristics of the optimum blade used in such propeller and shaftpower output and generated thrust in those conditions. Check that you make enough

thrusttoovercomethepredicteddragforceof185Natthiscondition.[20]

D–STRUCTURALDESIGN [20MARKS]

1. The initial design of a Boeing 747-400 commercial transport aircrafthas the followingcharacteristics:MTOWof397,000Kg;wingareaof525m2;ARof7.9;andCLmaxof2.1in

cruise/leanconfiguration.Theaircraftisdesignedtoflyatanaltitudeof35,000ft(9754

m)ataM=0.85.

(a) Determinetheoperational(limit)V-ndiagram

(b) Calculateandplotthebendingmomentandshearforcediagramsforthewingofthe

aircraft. For simplicity, consider the lift distribution tobe constantacross the wing

(chordwise)andapeakloadofn=4.14.Consider thatapylonmountedunder-wing

enginewillbeusedoneachhalfwing.Theengineisassumedtobemountedat7m

fromthewingroot(assumedtobeinthesymmetryplaceoftheaircraft)andtohavea

mass of 8,000 Kg. Neglect the structural weight of thewing and theweight of the

systems(suchaslandinggearandfuelsystem)inthewing.Thefollowingequationcan

beusedfortheliftdistributionalongthewing:L(y)=-8.3y+385kN .

E-STATICSTABILITY [20MARKS]

1. Due to stall behavior considerations an initial canard configuration design for a utility

aircrafthad tobechanged toconsidera threesurfaceaircraft(canard+wing+horizontal

stabilizer). Suchdesign ismeantto fly at low altitudeat a speed of120 kts.Thewingand

canardaregeometricallysimilar,whiletheadditionalthirdsurface(horizontalstabilizer)has

an AR = 2. Neglect the twist and downwash. Consider:m = 800 kg,

c = 1.5 m,

C M

0

= 0,

horstabcanard wing aaa == = 2π/rad, S wing= 18 m2, S canard = 6 m2, S horstab= 2 m2 and the distances

betweenthewingandcanarda.c.andthewingandhorizontalstabilizera.c.tobe9and6m,

respectively.

(a) Findthepointoftheconfigurationaboutwhichthemomentisconstant,independent

oftheangleofattack(neutralpoint).

(b) Toachieveanadmissiblestallbehavior itwasfoundthatthecanardangleofattack,

requiredtotrimforastaticmargin(stickfixed)of15%,hadtobe20%higherthantheoneof

thewing.Knowingthat, calculatetheanglesofattackof thethreesurfacesfor trimandthe

previously referred stick fixed static margin (if you haven’t solve the previous question

assumetheneutralpointtobe7mbehindcanarda.c.).



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Notes:

Segment Wi/Wi-1

1. Starting (taxi) and take off: 0,970

2. Climb: 0,985

3. Cruise (range): EXP{-R.C.g/[V.(L/D)]}

4. Hold (endurance): EXP[-E.C.g/(L/D)]5. Descent (may be included in 3 or 4): 1,000

6. Landing: 0,995

R – range [m]C – specific fuel consumption [kg/Ns]

V – velocity [m/s]

L/D – gliding ratio

E – endurance or holding time [s]

T/W

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Paer Ist Exame 1 Dec10 2012