payload range diagrams
DESCRIPTION
Payload Range DiagramsTRANSCRIPT
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Payload Range Diagrams
Explanation of the payload range diagram: Thepayloadrangediagramillustratesthetradeoffrelationshipbetweenthepayloadandtherangeofonesingleaircraft.Thepayloadreferstoallthemassthatistakenbyanairplane,excludingfuel.Thestructureofanaircraftisdesignedinordertobesustainacertainamountofloads.Theseloadsdependsontheamountofweightwhichiscarriedbytheaircraft.Hencethereisavaluefortheaircraftmaximumtakeoffweight,whichcanneverbeexceededortheframewouldcollapse.Oncetheaircraftisloadedwiththemaximumamountofpayload,theamountoffuelthatcanbeembarkedtoflyacertainrangeisthenlimitedbythemaximumtakeoffweight.Oncearrivedatsuchpoint,anyfurtherrangeisachievedonlybyreducingthepayload,whichfollowsanearlylinearrelationship.Still,theamountoffuelthatanairplanecancarryisalsolimited.Thatisthereasonthatatonesuddenpoint,thelinearrelationshipchangesdrastically.
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How to build up a payload range diagram:
1 - Collect all important data Inordertostartbuildingupapayloadrangediagramitisnecessarytoalreadyhavecompletedtheweightestimationcalculations.Youshouldknowaboutthefollowing:WtoWoeWpl
Point A: ThispointissimplyW(pl,max),atR=0
Point B: ThispointisW(pl,max),atR=maxformaxpayload
Point C: ThispointisW(pl)andR(max)whencarryingthemaximumamountoffuel.sincethefueltankshaveamaximumamounttheycancarry,thereisstillspaceforpayload.therefor,W(pl)isnotzeroherewhileW(f)ismaximum.
Point D: Here,W(pl)=0andW(f)=max.TherangeishigherthanatpointChere,becauseyouflyfurtherwithlessweightaboard.calculations:
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Point B: ForpointByouwillneedtofocusonBrequetsformula.Really,theonlythingyouhavetodoisfindoutthemaxrangetheairplanecanfly@maxpayload:
Asyoucansee,mostofthevariablesinthisformulaincludeconstants.Forajetaircraftweshouldbeprovidedwithinformationsimilartothis:
OuronlychallengeistofindoutwhatW4/W5is,sowecanuseitintheformula.Forthiswemuststartoffusingthisformula:
Wto(max)=Woe+Wpl(max)+WfStartoffbyfindingoutwhattheamountoffuelistheairplanecantakeonboard@maximumtakeoffweightandmaxpayload.(Note:Woe=We+Wtfo+WcrewandWe=a*Wto+b)Onceyouknowthat,youcanfindoutthefuelfractionWf/Wtofortheaircraft.Youshouldthenbegivenatablecontaininginformationoffuelfractionatdifferentphasessimilartotheoneshownbelow.Yourtaskistofindoutthefuelfractionforcruise(Note:Youmightneedtoincludeloiteranddiversionphases!)
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Recallthat:
SowehavealreadyWf/Wto,wecanfindoutMff:M f f = 1
WFWTO
OnceweknowMff,wecanfindoutW5/W4.Thentaketheinverseofit,andyoufinallyhaveW4/W5,whichyouneededinordertouseBrequetsformulasandfindpointB.
Point C ForPointCyoumustbegivenhowmuchfuelyouraircraftcantake@maxWto.Withityoucanthencalculatehowmuchpayloadcanbecarriedbyagainusing:
Wto(max)=Woe+Wpl+Wf(max)Andthen,therest,yes,youguessedit,isjustthesameprocedureastofindtherangeforpointB:justfollowthis:findfuelfractionfindMfffindW5/W4calculateRange
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Point D: Inthiscase,allpayloadistakenoutandyouflyatmaxWfinordertoachievemaximumrange.Thereforeourformulaforweightsreducesto:
Wto=Woe+Wpl+Wf(max)andagainwemustfindWto.Oncedonethat,just,yesyes,repeatwhatyoudidforpointBandC.