aircraft high lift devices

8/10/2019 Aircraft High Lift Devices

1/19

AE 321(04): Fundamental ofAerodynamics

Aircraft High Lift e!ices


2/19

"hat are High Lift e!ices#

$n aircraft design& high-lift devicesaremo!ing surfaces or stationary com'onentsintended to increase lift during certain

ight conditions


3/19

High Lift e!ices

Fla's

*lats and *lots

+lo,n Fla's


4/19

Fla's

Flapsare hinged surfaces mounted on the trailing edges ofthe ,ings of a -.ed/,ing aircraft to reduce the s'eed at ,hichan aircraft can e safely o,n and to increase the angle ofdescent for landing hey shorten taeo and landing

distances Fla's do this y lo,ering the stall s'eed andincreasing the drag

E.tending a's increases the camer or cur!ature of the ,ing&raising the ma.imum lift coecient / or the lift a ,ing can

generate his allo,s the aircraft to generate as much lift utat a lo,er s'eed& reducing the stalling s'eed of the aircraft& orthe minimum s'eed at ,hich the aircraft ,ill maintain ightE.tending a's increases drag ,hich can e ene-cial duringa''roach and landing ecause it slo,s the aircraft


5/19

y'es of Fla's

Plain ap: the rear 'ortion of airfoil rotatesdo,n,ards on a sim'le hinge mounted at thefront of the a'


6/19

y'es of Fla'sSplit ap:the rear 'ortion of the lo,er surface of the airfoilhinges do,n,ards from the leading edge of the a'& ,hilethe u''er surface stays immoile Lie the 'lain a'& thiscan cause large changes in longitudinal trim& 'itching thenose either do,n or u'& and tends to 'roduce more dragthan lift At full deection& a s'lit a's acts much lie as'oiler& 'roducing lots of drag and little or no lift


7/19

y'es of Fla'sSlotted ap:a ga' et,een the a' and the ,ing

forces high 'ressure air from elo, the ,ing o!erthe a' hel'ing the airo, remain attached to thea'& increasing lift com'ared to a s'lit a'


8/19

y'es of Fla'sFowler ap: s'lit a' that slides ac,ards at& eforehinging do,n,ards& therey increasing -rst chord& then

camer he a' may form 'art of the u''er surface ofthe ,ing& lie a 'lain a'& or it may not& lie a s'lit a' utit must slide rear,ard efore lo,ering


9/19

A fully e.tended douleslotted fo,ler a's eforelanding

A slotted fo,ler a's of a+oeing 545/400

y'es of Fla's


10/19

*lats and *lotsAnother common high/lift de!ice is the slat& a small

aerofoil sha'ed de!ice attached 6ust in front of the,ing leading edge he slat re/directs the airo, atthe front of the ,ing& allo,ing it to o, moresmoothly o!er the u''er surface ,hile at ahigh angle of attac his allo,s the ,ing to e

o'erated eecti!ely at the higher angles re7uired to'roduce more lift


11/19

*lats and *lots


12/19

*lats and *lots

A slot is the ga' et,een the slat and the ,ing

he slat may e -.ed in 'osition& or it may eretractale $f it is -.ed& then it may a''ear as anormal 'art of the leading edge of a ,ing ,hichhas slot he slat or slot may e either full s'an& or

may occur on only 'art of the ,ing (usuallyoutoard)& de'ending on ho, the liftcharacteristics need to e modi-ed for good lo,s'eed control 8ften it is desirale for 'art of the,ing ,here there are no controls to stall -rst&allo,ing aileron control ,ell into the stall


13/19

A319 slats during landing


14/19

y'es of *lats

Automatic / the slat lies ush ,ith the ,ing leadingedge until reduced aerodynamic forces allo, it toe.tend y ,ay of s'rings ,hen needed

Fi.ed / the slat is 'ermanently e.tended his issometimes used on s'ecialist lo,/s'eed aircraft(these are referred to as slots) or ,hen sim'licitytaes 'recedence o!er s'eed

o,ered / the slat e.tension can e controlled ythe 'ilot his is commonly used on airliners


15/19

+lo,n a's

o,ered high/lift systems generally use airo, fromthe engine to sha'e the o, of air o!er the ,ing&re'lacing or modifying the action of the a's

+lo,n a's use ;leed air; from the 6et engine


16/19

+lo,n Fla's


17/19

+lo,n Fla's


18/19

=/15 >loemaster $$$

The C-17 has a systemthat uses the airowfrom the enginesdirectly !y placing a ap

in the path of the


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End

aircraft high lift devices

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