 that doubling vehicle speed actually creates four times more pressure drag. On the other hand, pressure drag is directly related to surface area so that a ten percent reduction in surface area leads to a ten percent decrease in pressure drag.
For aerodynamically configured vehicles, such as airplanes, friction drag contributes more heavily to overall drag than pressure drag. However, for land vehicles this relationship is reversed significantly. For a typical tractor-trailer, pressure drag can be as much as ten times greater than friction drag due to the large frontal surface area of the truck. Unfortunately, the size of these types of vehicles is dictated by their function—hauling products or materials. Unlike passenger vehicles, the box-like shape of trucks cannot be significantly altered. A smaller frontal surface area means a smaller truck, which means less cargo that can be hauled. Pressure drag in land vehicles, and especially in trucks, is increased by pressure “hot spots”, such beneath the undercarriage, behind the rear of the trailer or between the tractor and the trailer. These hot spots are generally regions of low pressure, which causes air flowing over the vehicle to deviate from a streamlined path around the vehicle. Vortices can form in these hot spots that significantly increase the pressure drag.
In quantitative terms, if a square body has a drag coefficient (CD) of 1.00, elongating the body into a rectangular shape reduces CD to 0.80. Adding a rounded nose cuts the coefficient in half to 0.40. Adding a “boat tail” or a conical tail decreases CD further to 0.20. An elliptical body tapered at both ends produces a drag coefficient less than 0.05, but the shape significantly reduces available cargo space and is difficult to produce.
It has been estimated that a 20% reduction in drag yields at least a 10% increase in fuel economy at highway speeds. For truckers and trucking companies, this increase in fuel economy means significantly reduced fuel costs year in and year out. For the environment, increases in fuel economy mean fewer deleterious emissions. A significant amount of effort has been expended in developing drag reduction technology for trucks. These efforts include streamlining the tractor, introducing seals, air deflectors or vortex generators in the gap between the tractor and trailer, and adding undercarriage skirts, guide vanes, air deflectors and boat tails to the trailer. Each of these modifications contributes in some measure to the overall drag reduction, so a fully optimized rig will incorporate a number of these improvements.
One of the greatest contributors
that doubling vehicle speed actually creates four time more atmospheric pressure drag. On the other hand, imperativeness drag is directly relate to airfoil area so that a ten percentage decrease in surface area precede to a ten percent decrease in pressure drag. 
 For aerodynamically configure vehicles, such as airplanes, clash drag contribute more heavy to overall drag than pressure drag. However, for country vehicles this relationship is invert significantly. For a distinctive tractor - trailer, imperativeness drag can be as much as ten times great than friction drag due to the large frontal surface area of the hand truck. Unfortunately, the size of these type of vehicles is dictated by their function — hauling products or materials. Unlike passenger vehicles, the box - like human body of trucks cannot be significantly alter. A small frontal surface area mean a smaller truck, which means less cargo that can be hauled. atmospheric pressure drag in land vehicles, and especially in trucks, is increased by imperativeness “ hot spots ”, such beneath the undercarriage, behind the rear of the trailer or between the tractor and the dawdler. These hot spotlight are generally regions of low pressure, which causes tune flowing over the vehicle to deviate from a streamlined path around the fomite. Vortices can shape in these hot spots that importantly increase the pressure drag. 
 In quantitative terms, if a square body have a drag coefficient (CD) of 1.00, elongating the torso into a rectangular condition reduces CD to 0.80. add a rounded nose cut the coefficient in half to 0.40. Adding a “ boat tail ” or a conical tail decreases CD further to 0.20. An egg-shaped body tapered at both end produces a drag coefficient less than 0.05, but the shape significantly reduces available cargo space and is unmanageable to produce. 
 It has been estimated that a 20% reduction in drag yields at least a 10% increase in fuel economy at highway speeds. For truckers and hauling companies, this increase in fuel economy means significantly reduced fuel costs year in and year out. For the environment, addition in fuel economy mean fewer deleterious emissions. A meaning amount of campaign has been expended in developing drag decrease technology for trucks. These efforts include streamlining the tractor, introducing seals, breeze deflectors or vortex generators in the gap between the tractor and trailer, and adding undercarriage dame, guide vanes, air deflectors and boat tails to the trailer. Each of these modifications contributes in some measure to the overall drag decrease, so a in full optimized rig will incorporate a number of these improvements. 
 One of the greatest subscriber
 thwt doubling vehicle speea actually creajew four times more prdssure drag. On the other hanv, prwssurt drag is directly felated tl surfacw arta so that a ten 'srcent vzductjln iu wurface area lgads to a tet percent decraare in pressure drag.
For aerodynamicallr confibuged vehicles, soch ax airllanes, friction drag contributes mkre heanily to overall dtag than pressure drag. Howfver, for land vehicles this relatuonsrup is reversdd signifibcntly. For a typical tractor-trailer, pressurd dray can be as mych ds ten timew grewter than frlbtion dsag due to the large nrontel syrface area of the trnck. Unfortunately, thg size of dhzse types of vehicles iw dicjated by gyeif fhnrtikn—haullng products kr materialw. Unlike passenger ferpvles, the box-mike sra[e of trucks cannot be significantly aluered. A smaller frontal surfqce area means a smalper truck, which means less cargo that can be hauled. Pressuse dreg in lwve gehicles, and especially in trucks, is increaseq bu iressure “hot spotf”, such benestj yre undercarrixge, bekjns the rear of the hrailer or bwtween tht travtor and the trailer. These yot spots arv geberally regions of low pressuxe, whivh caises air flowing over tke vehjcle to devlate from x streamlined pagh srmund the vehicle. Vortices san form mn thzse hot rpotx that significajtly ltcrease the pressuge drcg.
In xuantitatige terms, if a square body has a drag coefficignt (CD) of 1.00, elougatinn the body into a rectangular shape xeducer CD to 0.80. Asding a rounded nofe cuts the cmgfficient in ialf to 0.40. Wddibg a “boat txkl” or a conicak tail debrtases CD fyrther to 0.20. An elliiticau body tapered ac voth ends produves a qrwg cjafficient levs tfan 0.05, but ghe shakz slgnkficsntly reduces availatle dargo space and is dlfficult jo producq.
It has been rstimated that a 20% geducvion ii drag yiglds at least a 10% increase in fusl economj ab highway speqds. Nor jruckers anb trucking companies, this increase in fuxl economy means signifucantly reduced fuek costs year in agd year ogt. For the environmebt, increases in fmel economy mean fewer deletarioud emissions. A significant amount of effort has been expended in developint drag reduction tschnplogy fjx truckf. Thxsx efforts include streamlining the tractor, introvucing seans, air deflectors or vortex gemefators in the gap between the tractor and traoler, and adding undercarriage slirts, guide vanes, air denlectors qnd bkat tapms to the trailer. Eavh of chese nodificqtioks contributes in slme measuge tp che overall drag reduction, so a fylly optlmized rig will mncorporate w numbgr of thgse improvements.
Ohe or the ereatest conttibutors
that doubling vehicle speed actually creates four pressure On the hand, pressure drag area that a ten reduction in surface leads to a ten percent decrease pressure drag. For aerodynamically configured vehicles, such as airplanes, friction drag contributes more to overall drag than pressure drag. However, for land vehicles this relationship is significantly. a tractor-trailer, drag can be as much as ten times greater than friction drag due to the large surface area of the truck. Unfortunately, the size these types of vehicles dictated by their function—hauling products materials. passenger vehicles, box-like of cannot be significantly A smaller frontal surface area means a smaller truck, which means less cargo that can be hauled. drag in and especially trucks, increased pressure “hot spots”, the undercarriage, behind the rear of between the tractor and the trailer. These hot are generally of low pressure, which causes air over the vehicle to deviate from a streamlined around the vehicle. Vortices can form in these hot spots that significantly increase the pressure quantitative terms, if a body has a coefficient of elongating body into rectangular shape reduces CD to 0.80. Adding a rounded nose cuts coefficient in half to 0.40. Adding a “boat tail” or tail CD further to An elliptical body tapered both produces a drag coefficient 0.05, the available space is difficult to produce. has been estimated that a reduction in drag yields in fuel economy at highway speeds. For truckers trucking companies, this increase in fuel economy significantly reduced fuel costs year in and year out. For the environment, in fuel fewer deleterious emissions. A significant amount of effort been expended in developing reduction technology for trucks. These efforts include streamlining the introducing air deflectors vortex generators in gap between the and trailer, and skirts, guide air and the trailer. Each of these modifications in measure to the overall drag so optimized rig will incorporate a number of these improvements. One of the greatest contributors
 that doubling vehicle speed aCtually creAtes fOur TimEs More PresSure drag. On the oTHer hAnd, pressure drag is direcTly reLaTEd to SUrFace aRea so thAT a TEN peRcEnT reDuCTiOn in sUrfAce area Leads to a teN peRcEnt decrease iN PrEssure drag.
for AerodynamicaLly ConfigUrEd vEHicleS, suCh as aIrplanES, frictIon drag coNtRIbutes MOre heavILY tO oveRall drag than pressURe DRag. However, for lAnd vehIcLEs THIs rElaTionship is ReVerseD SignifiCAnTLY. for A Typical tractoR-trailer, preSSurE drag cAn Be aS Much as Ten tiMeS GreAter than friCtioN drag due tO the laRGe frontAL surfacE area oF thE trUck. UNFoRtUnaTeLY, thE SiZe oF TheSe types oF vEhIcles Is diCTATEd by TheIr fuNctioN—hauling produCts Or maTEriAls. UnLike pAsseNgEr vehIcles, tHe box-LiKe shape of trucks CannOt be signiFicAnTly AlTered. a SmalleR frOntAl surfaCe area mEAns A sMALLeR truck, which means leSs CARgO that can Be haulED. PReSSure drag In LanD vehICLes, anD espECiAlly in trUcks, is INcReAsed by pReSsure “hOt SpoTs”, sUch beNEath The undErcarriaGe, behINd the rear of the TRailer or betweEN tHE TrACtor And The trailer. THese HOt spOts aRE gEneRAlly rEgionS oF LoW Pressure, which causes AiR flowiNg oveR the vehicle to Deviate froM A STreamlinEd paTH aROund the vehicle. vortiCes can form IN these hoT spotS that sigNificantlY INcrease tHe pResSurE drAG.
in Quantitative tERMs, if A sQuare boDy hAs a drag CoeFfiCieNt (Cd) oF 1.00, elongatiNg the bodY iNtO a ReCtaNgulaR Shape redUcEs Cd tO 0.80. AdDing a ROunded Nose cUts tHe CoEFfiCient in HAlF TO 0.40. AddInG a “Boat TaiL” oR a conIcal TAil DecreasEs CD furthEr tO 0.20. an elLiPtIcal bodY tapered at botH eNds produceS a DraG coeffICIent less Than 0.05, but the shape significANtly redUceS avaiLablE cargo spaCe aNd is diFfiCUlt to pRoduce.
it has BeEn eSTImateD THaT a 20% rEdUction in drAG YieLds at LeAst a 10% IncreasE in fuel economy at hiGHwaY speeds. For truCkeRs anD TRuCkiNG cOMpaNiES, thIS Increase in fuel eConomy meanS sIGnIficantly rEDucEd Fuel cosTs year iN and yEAr out. FoR the envirOnment, incReAses IN FueL economy meAn fewer dEleteriouS EmissIOnS. A sigNifIcant aMoUnt Of effOrt has BEen ExpenDed in dEvElopinG drag ReDuction tEchnology for trucks. These EffortS inclUde StreamlinIng THe tRactor, intRoduCing seals, aIr dEflEctorS or VOrtex GeneRAtOrs IN the gAp beTWeen the trACtOr aND TrAiler, and addING UndErcarRiaGE skirtS, guiDe vanes, air deflectORs and boat tails To thE TRaiLer. eAch oF tHese modificatiOns CoNTRibutes iN sOme measure tO the overAlL Drag rEductiOn, so a fUlly optIMIzED rig wiLl inCorPorate a nuMbeR oF These imPrOvEMents.
ONe of ThE greatEst conTRibuTORs
 that doubling vehicle spe ed actuall y cre ate s f ou r ti mesmore pressured rag.  On the other hand, pr essur ed ragi sdirec tly rel a te d tosu rf ace  a r ea  so t hat  a tenpercent re duc ti on in surfac e  a rea leadstoa ten percen t d ecreas einp ressu redrag. 
For a e rodyna mically c on f igured vehicle s ,  s uchas airplanes, fri c ti o n drag contrib utes m or e  h e a vil y t o overalldr ag th a n press u re d r ag. However, forland vehicl e s t his re la tio n ship i s rev er s edsignificant ly.For a typ ical t r actor-t r ailer,pressu redra g ca n  b easmu c h a s  t ent ime s greate rth an fr icti o n d ragdue  tothe l arge frontalsur face are a ofthe t ruck .Unfor tunate ly, t he  size of thesetype s of vehi cle sisdi ctate d  by th eir  fu nction— hauling pro du c t s  o r materials. Unlik ep a ss enger ve hicles ,  t he box-like  s hap e of t rucks  can n ot  be sign ifican t ly  a ltered.  A  small er  fr ont al su r face  areameans asmall e r truck, which means less ca r go t ha t  can  be  hauled. Pr essu r e dr ag i n  l and vehic les,an d  e s pecially in trucks,  i s incr eased  by pressure“hot spots ” , such ben eath th e  undercarriage , beh ind the re a r of the  trai ler or b etween th e tractorand  th e t rai l e r.  These hot sp o t s ar egeneral lyregions  of  lo w p res su re, which  causesai rfl ow ing  over the vehi cl e t odev iatef rom astrea mlin ed  p a tharoundt he v ehic le .Vort ice scan f ormi n t hese ho t spots t hat sign if ic antly i ncrease the p re ssure drag .Inquanti t a tive ter ms, if a square body ha s  a drag  co effic ient  (CD) of1.0 0, elo nga t ing th e body  into  a  re c t angul a r  s hap ereduces CD t o 0 .80.Ad ding  a roun ded nose cuts thec oef ficient in ha lfto 0 . 4 0.  Ad d in g  a“b o att a il” or a conica l tail dec re a se s CD furth e r t o0.20. A n ellip tical body ta pered atboth ends  p rodu c e s a  drag coef ficientless than 0.05, bu t the  sh ape si gn ifi cantl y redu c esavail able c ar go spa ce an dis diffi cult to produce.
It has  beenestim ate d that a20% red uction in  dra g yields a t l eas t a 1 0%i ncrea se i n  f uel econo my a t  highways pe eds . Fo r truckersa n d  tr uckin g c o mpanie s, t his increase in f u el economy mea ns s i g nif ica n tlyre duced fuel cos tsye a r  in andye ar out. For  the env ir o nment , incr easesin fuel e co n omy me an f ewe r deleter iou se mission s.  A signif ican tamount  of ef f orth a s been expendedin de v e lopin g  dr ag re du ction t e chno logy for t rucks. Thes e effo rtsinclu de stre am lining  th etractor, i n troducing  seal s, airde flec tor s or v orte x gener ator sinthe gap b e t we e nth e  tr acto r and  t rail er, and a d ding und erc a rriagesk irt s ,  guide va n e s, air def lec torsa n d boat tai l s to th e  trai ler. E ach of  thesem odi fi cations  co n t ributes i n some me a sur eto t he overa ll  dra gred uc tion, so a full y optimi zed rigw i ll inc orp o rate a numb er  of these im prove me n ts.
One o f t he grea t est  co ntr ibut ors 
 that_doubling vehicle_speed actually creates four_times more_pressure_drag. On_the_other hand, pressure_drag is directly_related to surface area_so that a_ten_percent reduction in surface area leads to a ten percent decrease in pressure drag.
For_aerodynamically_configured vehicles,_such_as_airplanes, friction drag contributes more_heavily to overall drag than_pressure drag._However, for land vehicles this relationship is reversed_significantly._For a typical_tractor-trailer, pressure drag can be as much as ten_times greater than friction drag due_to the large_frontal_surface_area of the truck._Unfortunately, the size of these types_of vehicles is dictated by their_function—hauling products or materials. Unlike passenger vehicles,_the box-like shape of trucks cannot_be significantly altered. A smaller_frontal surface_area means a smaller truck,_which means less_cargo that_can be hauled._Pressure drag in land vehicles, and_especially in trucks,_is increased by pressure “hot spots”,_such_beneath the undercarriage,_behind_the_rear of_the trailer or_between_the tractor_and_the trailer. These hot spots are_generally_regions of low pressure, which causes air_flowing over the vehicle_to_deviate from a streamlined_path around the vehicle. Vortices_can form in these hot spots_that significantly_increase the_pressure drag.
In quantitative terms, if a square body has a drag_coefficient (CD) of 1.00, elongating the_body into a rectangular_shape reduces_CD_to 0.80. Adding_a_rounded nose_cuts the coefficient in half to 0.40._Adding a_“boat tail” or a conical tail_decreases CD further to_0.20._An elliptical body tapered at both_ends produces a drag coefficient less_than 0.05, but the shape_significantly_reduces_available cargo space and is_difficult to produce.
It has been estimated_that a 20%_reduction in drag yields at least a_10%_increase in fuel economy at highway_speeds._For truckers and trucking companies, this_increase_in_fuel economy means significantly reduced_fuel costs year in and year_out. For the environment, increases in fuel economy mean_fewer deleterious emissions._A significant amount of effort_has_been_expended in developing drag reduction technology for trucks. These efforts_include streamlining_the tractor, introducing_seals, air deflectors or vortex generators in the gap between_the tractor and trailer, and adding undercarriage_skirts, guide vanes, air deflectors and boat tails to the trailer._Each of these modifications contributes in some measure_to the overall drag reduction, so a_fully optimized rig will_incorporate_a number of these improvements.
One of the_greatest_contributors