TheB2–BomberACloserLookattheB2Configuration

DavidCross,JoelFaber,andRaulTelles

AOE4124–TeamProject

April1,2009

BriefHistory•  TheB‐2isarevolutionaryaircraft•  Uniqueflyingwingconfigurationwiththefollowingdesignobjectives

–  Serveasamulti‐rolebomber–  Stealthwasextremelyimportant–  Hadtobeabletoflylongmissions

•  Development–  Beganinthe1970s–  FirstoffthelineinNovemberof1988–  FirstFlightwasJuly17,1989–  In1991,B‐2designteamwasawardedtheCollierTrophy

•  B‐2inAction:–  1999inKosovo–  2001inAfghanistan–  February22,2008,firstreportedaccidentofB‐2–  Humidityonsensorswereyieldingskewedpre‐flightchecks

Jane’sMilitaryAircraftRecognitionGuide,2007

SpecificationsFirstflight: 17‐Jul‐89Classification: BomberSpan: 172feetLength: 69feetGrossweight: 336,500poundsCruisingspeed: HighsubsonicRange: 6,000milesplusCeiling: 50,000feetPower: Four19,000‐pound‐thustF118‐GE‐100enginesAccommodation: 2crewArmament: Morethan40,000‐poundnuclearorconventionalweaponpayloadRunwayLength: 6500feetCost: $2billion

Jane’sMilitaryAircraftRecognitionGuide,2007

(67.28,0)

(48.20,43.84)

(56.75,13.00)

(59.63,86.00)

(69.80,72.60)

(63.15,21.34)

(0.0,0.0)

GeometryPlanformArea: 5118.55ft2

MeanAerodynamicChord: 39.47ftX‐Centroid: 40.21ftSpanwisepositionofMAC: 29.53ftX‐LeadingEdgeofMAC: 20.47ftQuarterChordofMAC: 30.34ftAspectRatio: 5.78AverageChord: 29.76ftTaperRatio: 0.00LESweep: 34.74deg

PictureSource:http://www.aerospaceweb.org/aircraft/bomber/b2/b2_schem_01.gifDataSource:UtilizedWingPlanAnalCodetogeneratedata

CGlocation

CGlocationwascalculatedbylookingatthesideprofileoftheB‐2.

Assuminga15°anglebetweenthelandinggeargroundcontactandthecglocationandassumingthecgwaslocatedforwardofthelandinggear,thecgwascalculatedtobearound33.2feetaftofthereferencedatumline.

NeutralPoint:32.98ftaftofnose

StaticMargin:0.22ft

ReferenceDatum

NP

PictureSource:http://www.aerospaceweb.org/aircraft/bomber/b2/b2_schem_01.gifDataSource:UtilizedVLMpcCodetogenerateneutralpointdata

x

z

CdoatVariousAltitudes

DataSource:UtilizedFRICTIONcodefromhttp://www.aoe.vt.edu/~mason/Mason_f/MRsoft.html

M=0.79

NotebyMason,thiswasrunatadifferentaltitude(Re)

SpanloadingComparison

DataSource:UtilizedLIDRAGCodefromhttp://www.aoe.vt.edu/~mason/Mason_f/MRsoft.html

e=0.96

Cl=1

TwistDistributionforMinimizedDrag

DataSource:UtilizedLAMDESCodefromhttp://www.aoe.vt.edu/~mason/Mason_f/MRsoft.html

OptimizedSpanloading

DataSource:UsedspanloadingdataoutputfromLAMDESprogramfoundathttp://www.aoe.vt.edu/~mason/Mason_f/MRsoft.html

SectionClforB2

DataSource:UtilizedVLMpcCodeoutputforsectionCL’sfromhttp://www.aoe.vt.edu/~mason/Mason_f/MRsoft.html

CLatVariousAltitudes

DataobtainedfromLiftequationatMach=0.79andthecorrespondingdensitiesforeachaltitude.

Lift–to–DragRatio

DataSource:http://www.aoe.vt.edu/~mason/Mason_f/ConfigAeroAppD.pdf

TakeoffandLanding

•  Groundeffect:-  Largeareaflyingwing-  Sitsoncushion-  Hastobe“forced”toland-  Notdifficult(2ndeasiesttotheF‐15)•  Stealthdesignledtogreatliftingfeatures.

ControlSurfaces•  B‐2has4pairsofcontrolsurfaceson

thewingtrailingedge.

1)Splitdragruddersonouterwing2)Oneelevononouterwing3)Twoelevonsoninnerwing4)Beavertail

•  Outerelevonsprovideprimarypitch&rollcontrol.

•  2innerelevonsconsideredsecondarycontrolsurfaces(usedatlow‐speed).

•  Beaver‐tailworksconstantlytoalleviategustloads. Atlowspeedflight,dragrudders

areopen.PictureSource:http://people.clarkson.edu/~pmarzocc/AE430/AE‐430‐5.pdfhttp://people.clarkson.edu/~pmarzocc/AE430/AE‐430‐5.pdfStabilityandControlofConventionalandUnconventionalAircraftConfigurations:ByBerndChudobaPage201http://science.howstuffworks.com/stealth‐bomber2.htm

Stealth

LowObservableCharacteristics

‐RADARcrosssection(RCS)

‐Infraredsignature

‐Appearance

‐ElectromagneticSignature

‐AcousticSignature

Picturesource:

http://www.is.northropgrumman.com/systems/b2spirit_assets/photos/hi/01top20_94a65408.jpg

Stealth

•  ThekeytoStealthisknowhowRADARwavesarereflectedoffabody.

•  RADARwavesreflectsimilartolightrays.

•  Alightraywillreflectoffasurfacethesameangleatwhichitencounteredthesurface.

•  TogetareturnaRADARreflectionrequiresasurfaceperpendiculartotheincomingwave.

θ θ

ReferenceData:http://www.aoe.vt.edu/~mason/Mason_f/ConfigAeroStealth.pdf

http://www.answers.com/topic/stealth‐aircraft

http://en.wikipedia.org/wiki/B‐2_Spirit

Stealth

TheB‐2outerprofilehasavariableradius/continuouscurvethatdeflectsRADARwavesatanyangle(non‐tangentialsurface).Thus,reducingit’sRCS.

It’sshapealsoallowsforaerodynamicflow.

Tofurtherreduceit’sRCStheskiniscoatedwithRADARAbsorbingMaterials(RAM)

Transmitter/receivers

target

PictureSource:

http://www.is.northropgrumman.com/systems/b2spirit_assets/photos/hi/01top20_95020910.jpg

ReferenceData:InsidetheStealthBomberByBillSweetman(page25‐26)

http://www.answers.com/topic/stealth‐aircraft

http://en.wikipedia.org/wiki/B‐2_Spirit

QUESTIONS???

Picturesource:GoogleImagesSearch“B2”