Aerodynamics Cont. (Lift) PDF

10. AERODYNAMICS! May$17,$2016$  LEARNING$OUTCOMES! On$comple>on$of$this$topic$you$should$be$able$to:$ Describe$about$aerodynamics$(cont.).$ 1. Thrust,$weight,$aerodynamic$resultant.$ 2. Genera>on$of$liO$and$drag.$ a. Angle$of$aPack.$ b. LiO$coefficient$ c. Drag...

10. AERODYNAMICS! May$17,$2016$  LEARNING$OUTCOMES! On$comple>on$of$this$topic$you$should$be$able$to:$ Describe$about$aerodynamics$(cont.).$ 1. Thrust,$weight,$aerodynamic$resultant.$ 2. Genera>on$of$liO$and$drag.$ a. Angle$of$aPack.$ b. LiO$coefficient$ c. Drag$coefficient.$ d. Polar$curve.$ e. Stall.$ 3. Aerofoil$contamina>on$including$ice,$snow$and$ frost.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 2!  10.4 THRUST, WEIGHT, AERODYNAMIC RESULTANT! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 3!  PRODUCTION$OF$LIFT! ! To!keep!flying!"!aircraA!must! produce!a!force!equal!to!its! own!weight.! ! Greater!force!–!to!liA!the! aircraA!!from!the!ground.! ! Force!(liA)!is!provided!by!the! wing.! ! The!producMon!of!liA!is!based! on!Bernoulli’s$theory.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 4!  Lift Thrust Drag Weight Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 5!  AERODYNAMICS$RESULTANT! It!has!been!stated!that!pressure!acMng!on!area!produces!a!force.!! The!force!(F)!resulMng!from!air!in!moMon,!is!termed!'an! aerodynamic!force'.!!The!pressure!distribu>on!is!then!replaced!by! an!arrow!represenMng!this!force!in!terms!of!magnitude!and! direc>on.! The!line!of!acMon!of!the!force!determines!the!centre!of!pressure;! i.e.!that!point!(CP)!on!the!chord!line!through!which!the! aerodynamic!force!can!be!considered!to!act.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 6! 10.5 GENERATION OF LIFT AND DRAG! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 7!  CAMBER$(CURVED)$ Airflow!around!the!cambered!wing!behave!exactly!as!airflow! in!a!venturi!tube.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 8!  AIROFOIL! 1. To$understand$how$an$airfoil$works$it$is$useful$to$first$look$at$what$happens$to$ a$slow$speed$flow$through$a$contrac>on$or$venturi.$ $ $ 2. Bernoulli$states$that$the$sum$of$the$energies$at$posi>on$1$in$the$duct$shown$in$ the$figure$are$the$same$as$the$sum$of$energies$at$posi>on$2.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 9!  AIROFOIL! ↓ bigger that ! 1 2 1 2 ρgh 1 + ρv1 + P1 = ρgh 2 + ρv2 + P2 ! 2 2 3. The$total$energy$at$2$must$equal$the$total$energy$at$1.$ 4. By$inspec>on$the$fluid$has$to$go$faster$at$posi>on$2$than$posi>on$1,$so$V$at$ posi>on$2$has$to$increase.$ 5. This$means$that$the$sum$of$the$terms$on$the$right$is$bigger$than$the$sum$of$the$ terms$on$the$leO.$So$at$least$one$of$the$terms$on$the$right$must$reduce$ 6. The$centerline$(h)$is$horizontal$and$the$height$of$the$centre$line$does$not$ change,$so$P$at$posi>on$2$must$be$lower$than$P$at$posi>on$1.$Thus$the$ pressure$drops$ 7. If$the$air$was$to$enter$a$convergent$duct$at$speeds$at$or$above$the$speed$of$ sound$then$it$would$behave$as$if$it$was$compressible.$For$these$speeds$ Bernoulli$does$not$apply.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 10!  AIROFOIL! 1. If$we$reverse$the$venturi$sides$and$we$put$the$low$pressure$areas$on$the$ outside$of$the$shape$then$we$have$makings$of$an$airfoil.$ 2. The$wings$of$aircraO$are$of$an$airfoil$shape,$as$indeed$are$the$tailplane$ (stabilizer)$and$fin.$ ! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 11!  AIROFOIL! 3. The$previous$drawing$shows$a$symmetrical$aerofoil,$which$is$not$used$very$ oOen$on$aircraO.$ 4. The$more$usual$aerofoil$for$low$speed$aircraO/helicopter$blades$is$ asymmetric$with$a$well$rounded$leading$edge$and$a$straighter$boPom$ surface.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 12!  AIROFOIL! 5. This$type$of$aerofoil$will$produce$a$nega>ve$pressure$on$the$top$surface$and$a$posi>ve$ pressure$on$the$boPom$surface.$ 6. The$pressure$distribu>on$indicated$in$the$figure$with$each$vector$line$in$the$drawing$ indica>ng$the$amount$of$liO$produced$from$that$part$of$the$airfoil.$ 7. These$can$be$added$together$to$give$one$total$air$reac>on$vector$ac>ng$from$the$centre$ of$pressure.$ ! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 13!  AIROFOIL! 8. The$total$air$reac>on$can$be$ lift at t e righ airflow organized$into$component$vectors$ –$liO$&$drag$ 9. LiO$vector$always$acts$at$right$ angles$to$the$airflow$and$drag$ vector$always$acts$at$right$angles$ at to$the$liO$vector$and$inline$with$ the$airflow.$ drasingle p Y To 10.$Figure$on$the$right$shows$how$the$ liO$and$drag$vectors$are$summed$ lift to$give$the$total$air$reac>on$on$the$ airfoil. lift + drag Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! = total direction Abdul!Razak! 14!  AIROFOIL! 11. When$an$object$moves$through$the$air$it$sends$out$pressure$waves$forward$ into$the$airstream.$ 12. The$pressure$waves$warn$the$oncoming$air$of$the$object’s$approach,$and$as$ the$air$gets$near$to$the$object$so$the$air$will$start$to$move$out$of$its$way$–$ this$is$called$Upwash.$ 13. As$the$air$leaves$at$the$trailing$edge$the$air$will$be$deflected$downwards$–$ this$is$called$Downwash.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 15!  LIFT$THEORY$ LiA!is!a!mechanical!force!generated!by!a!solid! object!moving!through!a!fluid.! There!are!many!explanaMons!for!the!generaMon! of!liA!found!in!encyclopaedias,!in!basic!physics! textbooks,!and!on!Web!sites.!! Unfortunately,!many!of!the!explanaMons!are! misleading!and!incorrect.! LiA!can!be!explain!by!using!two!Theorem;! 1. Pressure!Difference!(Bernoulli’s!Theorem)! 2. Newton’s!Third!Law!! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 16!  LIFT$THEORY! LiA!is!defined!as!the!component!of!the!total! aerodynamic!force!perpendicular!to!the!flow! direcMon,!and!drag!is!the!component!parallel!to! the!flow!direcMon! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 17!  BERNOULLI’S$THEOREM$ Daniel$Bernoulli$found$out$that$when$velocity$of$ a$fluid$increases,$its$sta>c$pressure$decreases.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 18!  BERNOULLI’S$THEOREM! # The! Theory! of! Flight! is! oAen! explained! in! terms! Bernoulli's$ Equa>on! which! is! a! statement!of!the!Conserva>on$of$Energy.!It!states!that:! For$a$nonjviscous,$incompressible$fluid$in$steady$flow,$the$sum$of$ pressure,$poten>al$and$kine>c$energies$per$unit$volume$is$constant$at$ any$point.$ # In!other!words,!ignoring!the!potenMal!energy!due!to!alMtude:! ! When$the$velocity$of$a$fluid$increases,$its$pressure$decreases$by$an$ equivalent$amount$to$maintain$the$overall$energy.$This$is$known$as$ Bernoulli's$Principle$ !! # According! to! Bernoulli's! Principle,! the! air! passing! over! the! top! of! an! aerofoil! or! wing! must! travel! further! and! hence! faster! that! air! the! travelling! the! shorter! distance!under!the!wing!in!the!same!period!but!the!energy!associated!with!the!air! must! remain! the! constant! at! all! Mmes.! The! consequence! of! this! is! that! the! air! above!the!wing!has!a!lower!pressure!than!the!air!below!below!the!wing!and!this! pressure!difference!creates!the!liA.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 19!  BERNOULLI’S$THEOREM$ Air$velocity$increase$–$the$pressure$decreases$(and$vice$ versa).$ The!total!energy!of!a!moving!fluid!is!made!up!of!three!forms! of!energy:! $ !PotenMal!Energy!–!due!to!height&or&posi+on& $ !KineMc!Energy!–!due!to!mo+on& $ !Pressure!Energy!–!due!to!pressure& In!a!streamline!flow!of!an!ideal!fluid,!the!sum!of!all!those! xignoredfra energy!is!constant.! !!Poten>al$+$Kine>c$+$Pressure$=$Constant$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 20!  VENTURI$EFFECT$ A!short!circular!tube!with! large!opening!at!both!the! front!and!rear!end!+! restrictor!between!the! opening!! Venturi!is!a!convergent/ divergent$duct$ Bernoulli’s!Theory!is!being! proven!by!passing!a! streamline!flow!of!air! through!a!venturi!duct.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 21!  VENTURI$EFFECT$ Air$flow$through$a$venturi$we$see$that$the$streamlines$are$forced$together$were$the$ speed$is$greater$and$the$pressure$is$lowest.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 22!  VENTURI$EFFECT$ INLET! CENTRE!(THROAT)! OUTLET! Airspeed!normal! Airspeed!maximum! Airspeed!decrease! Pressure!normal! Pressure!minimum! Pressure!increase! (equal!to!inlet!area)! ! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 23! FLUID$FLOW$SIMULATION$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 24! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 25!  On$the$airfoil$as$the$air$flowing$on$top$of$the$ airfoil$upper$camber,$it$will$move$faster$ resul>ng$in$decrease$of$pressure.$ At$the$boPom$surface$the$air$move$slower$in$ rela>ve$to$upper$air,$therefore$the$pressure$is$ greater$at$the$boPom.$$ This$differen>al$pressure$will$provides,$certain$ amount$of$liO$on$the$airfoil.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 26!  Note$that$the$veloci>es$are$much$higher$at$the$upper$surface$than$at$the$ lower$surface.$$ The$black$dots$are$on$>melines,$which$split$into$two$–$an$upper$and$lower$ part$–$at$the$leading$edge$ The$part$of$a$>meline$below$the$aerofoil$does$not$catch$up$with$the$one$ above.$$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 27!  NEWTON’S$LAW! # Newton’s$third$law$states$that$for.every.ac0on.there.is.an.equal. and.opposite.reac0on.$ # This! means! that! the! force! of! the! aerofoil! pushing! the! air! downwards,! creaMng! the! downwash,! is! accompanied! by! an! equal! and!opposite!force!from!the!air!pushing!the!aerofoil!upwards!and! hence!providing!the!aerodynamic!liA.! # It!is!thus!the!turning!of!the!air!flow!which!creates!the!liA. !! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 28! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 29!  down wash Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 30! Airflow!on!wing!(LiA!distribuMon)! Increased!Speed! Provide 70% of the wing’s Total Lift Decreased!Speed! Decreased pressure 70%!of!Total!LiA! Increased pressure Providing 30% of the wing’s Total Lift Decreased!Speed! Increased!Speed! 30%!of!Total!LiA! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 31!  CENTRE$OF$PRESSURE$ Each$parts$of$the$airfoil,$will$experience$different$ forces$caused$by$the$pressure$difference$and$also$ by$the$direc>onal$change$of$the$airflow.$$ This$changes$can$be$ normally$represent$ by$airfoil$pressure$ distribu>on.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 32!  But$in$prac>cal$applica>on,$it$is$quite$difficult$ for$us$to$work$with$the$pressure$distribu>on$ diagram.$ Therefore,$for$prac>cal$purposes,$the$total$ summa>on$of$this$pressure$distribu>on$is$ represented$by$Center$of$Pressure$(C$of$P)$ ac>ng$at$a$point$on$the$airfoil.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 33!  xz frm lendered At$normal$angle$of$aPack$the$C$of$P$will$act$at$ about$1/3$from$the$leading$edge.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 34!  as X moreorwad lease For$asymmetrical$airfoil$,when$angle$of$aPack$is$ increases,$the$C$of$P$will$move$forwards$usually$up$ to$¼$from$the$leading$edge$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 35! Airflow!separaMng!from!a!wing!at!a! high!angle!of!ajack! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 36!  For$asymmetrical$airfoil,$when$angle$of$aPack$is$ reduce,$the$C$of$P$will$move$backwards$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 37!  CENTRE$OF$PRESSURE! Determined!through!calculaMon!and!wind!tunnel! test!by!varying!the!airfoil’s!AoA.!! A!point!on!the!chord!line!of!an!airfoil!at!which!all!of! the!aerodynamic!forces!are!concentrated.! Expressed!as!a! percentage!of!the!chord! of!the!airfoil.! – Example:!CP!at!30%!of!an! airfoil!with!60kinch!chord!is! 18!inches!aA!of!the!leading! edge.!! ! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan!Abdul!Razak! 38!  LIFT$FORMULA! LIFT$PRODUCED$BY$AN$AEROFOIL$DEPENDS$ON:$ 1. Shape$and$Angle$of$APack$(CL)$ 2. Air$Density$(ρ)$ 3. Air$Velocity$(V)$ 4. Plan$Wing$Area$(S)$ 2 The$Formula$will$be$:$$ L = ρV SCL 1 2 Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 39!  EXAMPLE! Density!at!5000!feet!=!0.9!kg/m3! At!2º!AoA,!CL!!=!0.5! Takeoff!velocity!of!aircraA!=!200!km/hr! ! ! ! ! ! !!!!!=!55.56!m/s!! AircraA!wing!area!=!140!sq.!m! EquaMon!=!L!=!½ρV²SCL! ! !=!½x0.9x55.5555²x140x0.5! ! ! ! !=!97222.0278!N! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan!Abdul!Razak! 40!  LIFT$FORMULA! % The$equa>on$½ρV2$is$some>mes$called$the$ dynamic$equa>on$and$is$given$the$designa>on$ q.$ % $That$is$q$=$½ρV2.$ % $The$liO$equa>on$could$therefore$be$wriPen$as$ CLqS.$ % $q$is$used$in$many$other$calcula>ons$including$ those$related$to$pitot$sta>c$instruments$and$the$ calcula>on$of$drag.$$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 41!  LIFT$COEFFICIENT! The$coefficient$of$liO$(CL)$is$determined$by:$$ %The$shape$of$the$wing,$$ %The$wing$aerofoil$sec>on/planform$ %Angle$of$aPack$(AOA).$! $ The$coefficient$of$liO$is$normally$derived$from$ wind$tunnel$tes>ng.$$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 42!  FACTORS$THAT$EFFECT’S$ LIFT! From$the$liO$equa>on$we$can$see$that$liO$is$ effected$by$:$ Air$Density$$ Speed$ Wing$Size$ Coefficient$of$LiO$ 2 L = ρV SC L 1 2 Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 43!  WING$AREA$ The$amount$of$liO$generated$by$an$object$ depends$on$the$size$of$the$object.$$ LiO$is$an$aerodynamic$force$and$therefore$ depends$on$the$pressure$varia>on$of$the$air$ around$the$body$as$it$moves$through$the$air.$$ The$total$aerodynamic$force$is$equal$to$the$ pressure$>mes$the$surface$area$around$the$body.$$ LiO$is$directly$propor>onal$to$the$area$of$the$ object.$$ Doubling$the$area$doubles$the$liO.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 44!  WING$SHAPE$($CAMBER$)! The$amount$of$liO$generated$by$an$object$ depends$on$how$much$the$flow$is$turned,$which$ depends$on$the$shape$of$the$object.$ Normally$we$talk$about$the$shape$in$terms$of$ camber.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 45!  ANGLE$OF$ATTACK$ The$magnitude$of$the$liO$generated$by$an$object$ also$depends$on$how$it$moves$through$the$air.$ We$calls$this$as$Angle$of$APack$ For$thin$aerofoil$the$liO$is$directly$propor>onal$ to$the$angle$of$aPack$for$small$angles$(within$+/j$ 10$degrees).$$ For$higher$angles,$however,$the$dependence$is$ quite$complex.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 46!  As$you$can$see$from$the$graph,$at$low$angles,$the$ liO$is$nearly$linear.$$ No>ce$on$the$plot$that$at$zero$angle$a$small$ amount$of$liO$is$generated$because$of$the$ aerofoil$shape.$$ If$the$aerofoil$had$been$symmetric,$the$liO$would$ be$zero$at$zero$angle$of$aPack.$ $At$the$right$of$the$curve,$the$liO$changes$rather$ abruptly$and$the$curve$stops.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 47! a. The$liO$and$drag$of$an$aerofoil$depends$on$three$factors:$ a. The$liO$and$drag$equa>ons$ b. The$angle$of$aPack$ c. Wing$configura>on$–$for$fixed$wing$aircraO$the$use$of$slats,$flaps,$ and$spoilers$affect$liO$and$drag$considerably.$ b. $An$increase$in$the$angle$of$aPack$will$result$in$an$increase$in$the$ amount$of$liO$produced$but$with$an$aPendant$increase$in$drag.$ c. $As$the$angle$of$aPack$increases$so$the$airflow$has$more$difficulty$in$ remaining$laminar$on$the$top$surface.$ d. $At$approximately$15o$angle$of$aPack,$the$airflow$can$no$longer$remain$ laminar$on$the$top$surface$of$the$aerofoil$and$it$will$become$turbulent.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 48! % !This!will!destroy!the!liA!in!this! area!and!the!drag!will!increase! sharply.! % !This!is!called!Stalling!Angle.! % !Recovering!from!a!stalling! condiMon,!the!pilot!pushes!the! throjles!forward!(more!power).! % !Stalling!is!usually!accompanied!by! buffeMng!and!someMmes!loss!of! control!and!possible!engine! problems.! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 49! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 50! % With!rear!mounted!jet!engines!the!turbulent!air!from!the!wings!can!someMmes! cause!the!engines!to!stall!(turbulent!air!in!the!intakes!causing!the!compressor! blade!to!stall)! % !With!stalled!engines!and!ineffecMve!elevators!the!aircraA!is!in!very!serious! trouble.!! Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 51!  LIFT$AUGMENTATION! 1. LiO$is$increased$for$landing$and$takejoff$by$the$used$of$leading$edge$slats$and$ trailing$edge$flaps.$ 2. LiO$can$be$increased$in$flight$by;$ a) Increasing$the$airspeed$ b) Increasing$the$angle$of$aPack$ c) Increasing$the$effec>ve$camber$of$the$mean$camber$line$ d) Increasing$the$stalling$angle$–$some$flaps$and$leading$edge$devices$ e) Increasing$the$wing$area$ f) Using$the$ailerons$as$flaps$–$using$the$ailerons$in$a$combined$roll/flap$ mode$called$ flaperons $ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 52!  LIFT$AUGMENTATION! 3. LiO$augmenta>on$generally$refers$to$leading$and$trailing$edge$devices$which$ means$flaps,$slats,$etc.$ 4. A$Clean$Wing$ a) Every$thing$moveable$and$ aPached$to$the$wing$is$either$in$ or$up.$ b) If$we$can$make$the$Mean$Camber$ Line$(MCL)$more$cambered$or$ make$it$longer$(bigger$wing$area)$ then$liO$will$be$increased.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 53!  LIFT$AUGMENTATION! 5. The$effec>ve$MCL$becomes$more$cambered$when$flaps$are$lowered,$which$ means$liO$is$increased$–$by$about$60%$ 6. The$stalling$angle$is$not$affected$significantly.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 54!  LIFT$AUGMENTATION! Fowler$Flap$ 1. Fowler$type$flap$which$not$only$goes$ down$when$selected$but$also$travels$ rearward.$ 2. This$means$that$the$wing$area$is$ increased$as$well$as$the$camber$of$ the$MCL.$ 3. The$increase$in$liO$for$this$type$of$ flap$is$up$to$90%.$ 4. The$double$sloPed$fowler$uses$ addi>onal$small$slat$type$aerofoil$in$ front$of$the$main$flap$–$produce$up$ to$100%$more$liO.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 55!  LIFT$AUGMENTATION! Krueger$Flap$ 1. It$is$a$structure$that$is$hinged$forward$ to$increase$the$camber$of$the$EMCL,$ and$it$also$increases$the$wing$area.$ 2. Increases$the$liO$by$50%.$ Slat$ 1. This$increases$the$EMCL$slightly$as$well$ as$the$wing$area.$ 2. Its$main$advantage$is$that$it$controls$ the$boundary$layer$on$top$of$the$wing.$ 3. Increases$the$liO$by$60%.$ Prepared!By:!Wan!Nur!Shaqella!Bte!Wan! Abdul!Razak! 56!