Wind-tunnel investigation of seven thin NACA airfoil sections to determine optimum double-slotted-flap configurations

Document

I

-., . . .

FORAERONAUTICS

.- .,

TECHNICAL NOTE

No. 1545

VIND-TUNNEL INVESTIGATIONOF SEVEN THIN NACA AIRFOIL SECTIONI

TO DETERMINEOPTIMUMDOUBLE-SLOTTED-FLAP CONFIGURATIONS

.. ..-

By JonesF. Cahill andStanley

F. -CiSZ

Langley Memorial Aeronautical

Laboratory

------ Langley Field, Va.

--— .. .+ ,..

Washington

.—--- .-— —.’:

April 1948 ‘

—-

NA C A LIBRARY -

LANGLEY MEMOIUAL AERoNAuTlcA4

MEOR.ATORY

.t bngley Field. v~

I?JITIONAL ~SORY COMMITTEE FORAERONAUTICS

TI&NmAL m!m I?o l 1545

WTNBTUNMEL IXVESTIGATIOR OF SEVEN TMJ3? l’?ACA AIRFOIL SECTIONS

~ TO DFTERMREOF’ITMUM DOUBI&S LO’l?EbFLAP CONFIGURATIONS

I& Jones F. Cahill endStanley F. Racisz

An investigation wasmadeto determine optimum double-slckted-

flapconfigurations forseven thinNACAairfoil sections. Theairfoils

tested werethe?lACA 6+210, 64-20f3, 64-210,641-212, 65-210, 66-210,

and1410airfoil sections. Eachof theairfoil sections tested was

equipped witha mainflapof 0.250chordd a fme f~p of 0.075 chord.

Inaddition, theNACA6&210 endtheNACA64-2C8 airfoil sections w~e

sJ.so tested witha O.100-ch@enda 0.05khmd fcmeflap, respectively.

Liftmeasurements weremadeat a Reynolds number of 2.4x Id to obtain

theconfiguration giving thehighest maximum section liftcoefficient

(ideal position) foreachof theairfoil sections tested.me Ilft

characteristics weremeasured forReynolds numbers up to 9.0 X ld in

Thesection pitchi~

ordgr to obtain en indication of thescale effects.

monmnt characteristics andtheeffect of leadi~dge roughness on the

liftcheracteristfce were aeured foreachof theairfoil sections at a

3 fora double-slotted-flap position close to

. %ynoldsnumber Of 6.ox I

theideal which alsoallowed thedouble slotted flapto be ret~acted as

a unitintothewingcontour (optimum).

Theoptimum fore-flap positions weregenerally found to be about

1 percent chord forward andabout ‘2 percent chord helm theslot lip.

The optimum flapposltione v=ied co~lderabN, me ~flectio~ f~ ““ - ‘;

whichthehighest rmxclmum liftcoefficients weremeaswedwereabout

. . .. —

50° -to 55°fortheflapandabout 25°to 39°.for theforefl+p? _

Themaximum section liftcoefficient of thea~rfoil section with

. . either a split or double slotted flapdecreased as theposition of

mimimum nressure wasmoved to theresr or as theairfoil thickness was

decreased to 0.08chord.In allcases, themaximum section lift

coeffici nt increased as theReynolds number was increased from

2.4 X d to 6 .0 X 106 butgenerally decreased remained c nstant a.s

—

$ (3 tog.oxl .

theReynolds number was increased from6.0 X 1

NAC!ATN No. 1545

Increasing thefor-flapchord provided increases in themaximum section

liftcoefficients of boththeNACA64-208 andtheRACA6210 a~rfoil

of atamdard roughness

sectlone withdouble slotted flaps.Theaddition

to theleading edges of theairfoils equipped wfthdouble clotted flaps

generally decreaeed themaximum section iii%coefficients by amounts

slightly lessthanthose obtained withtheflaps retracted, decreased

the variation of themaximum section liftcoefficient withposition of

minhumpressure andwithairfoil thickness, andcaused thestallsto be

lessabrupt thanthose forthesmooth condition. Theratioof increment

nt coefficient to incre~nt,of section Hft

of section pitchi~

&

coefficient at a sectiti angle of attack of 0° ~ based on the

ik~

()

Uo=oo

total chord of theairfoil withthedouble slotted flapextetied was

apprazimately theS- as thatobtained fw theairfoil withthesplit

flap. An unstable pitchin&mcment break wasencountered at thestall

foreachof thedrfoils when equipped withthedouble slotted flapsszxl

seemed to be peculiar to double slotted flaps.

Theuaeof thinwingsections to ~ncrease thecritical speedsof

hi-speed,highly loaded airplanes hasbeenaccompanied by theneedfor

e

suitable hfg~llft devices to be usedfortake-off endlanding. An

investigation wasmadein theLangley twtifmenslonal low-turbulence

tunnels to determine high-lift trailing-edge flaps suitable for useon #

thinwings,ectlons thataremostllkely to be usedon hig&speed aircraft.

‘l’he first partof thislnvestlgation, reported in reference 1, covers

thetests of fourtypes of flapfortheNACA 65-210 airfoil section. The

double slotted flap, discussed inreference 1, gavemaxhumliftcoef-

ficients higher than~ oneof thethree single slotted flaps tested.

Thesecond mxrtof thisWvestlgetion, reported herein, covers thetests

of slmilsr doubl-slotted-flap configurations forsixother thinHACA

airfoil sections. Datafromreference 1 on theNACA 6>210 airfoil

section witha double slotted flapareincluded to complete thecomparison

of theresults obtained.

Theseven thinNACAairfoil sectlans tested withdouble slotted

flaps in theIangley twti3mensional low-turbulence tmmnels axeas

foUmws: NACA 6w210, 64-2@, 64-=0, ~1-212, 65-210, 6210, end1410

airfoil sections. I&ofiles of theplain airfoil sections exeshown in

“ figure 1.

Theidealmex liftconfigurations were determined at a l?eynoldB

P number of 2.4 x 1 foreachof thedouble slotted flaps whichconsisted

of a 0.2~0-chord mainflapanda U.07!Echord foreflap. Thesection

icswerethenmeasured at higher

liftandpitchi~cmentCharacterlst

NACATN No. 1545

-

Reynolds numbers up to 9.0x 106forconfigurations thatnotonlyapproxi-

matedtheideal maximum lift mnfimrations butthatslsoalluwed the

flapandforeflapto retract as a-unit within theairfoil contour. The

effects of lead~dge roughness on thesection liftchsracterist ics

weredetermined ‘at ‘aReynolds number of 6.0 x 106.

Datacm theliftSIXI ~itc~ nt characteristics of these airfoil

sect ionsequipped with0.2&chord split flaps deflected 600areincluded

to showa comperisan between theeffects of thetwotypes of flap.

Sm’mYIs

section angleof attack, degrees

=0

c airfoil chad withflapretracted

c1

section liftcoefficient

c~

maxhu.m

section liftcoefficient

msx

<.-----

section pitch~oment coefficient about quert~hord

cm

c/4

point

*

flapdeflection (seefig.2)

8f

for&flapdeflection, measured between farc+flap

8ff *

chord lineandairfoil chord line, degrees

x~c distance slong airfoil chord 13ne, fkctlonof chti

tic d2?fOil thickness, fraction of chard

horizontal - vertic&positions, res~ctivdy,of the

X13 71

fcme-flap reference point measured fromtrailing edge

of slotMp In percent chord(xposttive fcrrward and

y positive down)(fig. 2)

,—

hcmizontal d vertical positions, respectively, of fh~

*, 72

reference point measured fromtraillng edgeof fore

flapin percent chord(x positive forward snly positive

down)(fig. 2)

R Reynolds number

4 NACATN No. 1545

increment of secticm liftcoefflchnt

‘z

increment of seotion pitch~mcment coefficient

%

MODELS

Eachof themodels tested hada chord of 24 inches andcompletely

spanned the+foot-wide teatsecticxm of thetwotunnels. Themain

pertof eachmodel ahead of theflapwas constructed of I_amlnated

mahogany, andtheflaps wereconstructed of steel.A typicel airfoil

withdouble slotted flapsincluding theessential dimensions, 18 shown

in figure 2. Ordinates fortheplain airfoil sections aregiven In

tables 1 to 7.

Eachof the main flaps was of 0.250 chord ti wasobtdnedby

scaling theordinates of themainflaptested on theNACA 65-210 afrfoil

section (reference 1) inproportion to theairfoil thickness at each

of theflaps tested aregivenin

station along thechord.Ordinates

tables 8 to 14. Eachof theflaps wastested in combination withthe

0.075c foreflapusedinreference 1. In addition, the NACA 6h-208

airfoil wastested witha 0.056c fcmeflapandtheNACA 66210 airfoil

wastested witha O.IOOC foreflap. Sketches

of thethree foreflaps

are presented as figure 3, and their cmdinates me given in tables 15 to

17. The flaps andftmeflaps wereattached to themainparts of the

models at theendsIn sucha manner thattheycould be setat anydesired

positicms anddeflections. Theflapemdfore-flap positions weremeasured

fromtheir reference points, which aredefined as theintersection of

their chord lines withtheir leading edges. (See fig.2.)

Fortests of eaohmodelin thesmooth c-ition, themodel wassanded

withNo.400cerb-um paper to produce aer~csUy smooth surfaces.

Fartests of theairfoil withleaddng-edge roughness, thesurfaces were

thesameas fcmthesmooth condition except thatO.011-inch cerbcmundum

graiqs wereapplled avera surface length of 0.16chard centered at the

chard line. Thisleadin&&l~roughness ccadition corresponds to the

standaxd roughness described inreference 2.

APPARATUS ANDT!ESTs

Theinvestiga.tlcmwas tie h theHey twcHHmensional 1-

turbulence tunne~ andtheIangley tuo-dim?&si-&nal lcn+turbulence pressure

tunnel.

NACA!L!N NO. 1545

Section liftcharacteristics wereobtained hornstatic-~eseure

*

measurements along thefloor endceiling of thetunnel test section, —

andsection pitchi~mcmsnt chracterlstics tiredetermined from

of thetestmethods sndthe

deflections of a torque tule. Details

methods usedin correcting thedatato freeairconditions erejgiven

Inreference 2.

Liftmeasurements weremadeat a Remoldsnumber of 2.~X 106 in

theTangley two-dimensional low=hrbulence tunnel to obtain the ideal

confQurations. Theideal configurations (those giving thehighest

—

mexhmun liftcoefficients) weredetermined by first determining the

ideel position of theflaprelatfve to theforeflapforseverel combi-

me configuration giyi.% the._.. .: nations of flapandforeflap deflections.

h~ghest msxinmm liftwas,if necessery, altered slightly to allow the

flapandforeflapto be retracted as a unitwithin the wing contour.

Withthepositicm of theflapthusfixed relative to thefcmeflap,lift “-—

measurements weremadeto obtain thebestposition of-the flapandfore-

flapcombination. Thisresulting position 3s cadled theoptimum position.‘“

Theopt- positions developed in theLengley twg-dimensional lcn+

—

turbulence tunnel at eachof severel deflections werethentested in the

_Y*~~ onsllmtibtience ~essuretunnel at a Reynolds

& ger of 6.ox1 . Forthecmfiguration @v thehighest mexhum

$$

liftcoefficient at a Reynolds n~er of 6.o x 1 , pitch$ng=ncment

characteristics d theeffect of leadin&edge roughness on thelift

characteristics werealsodetermined at a Reynolds number of 6.o x 106,

& sndthe iftcharacteristics weredetermined at Rewlds numbers of

end 9.0 X106. Themximm free-streamldach number attained

3.0 x 1d

—

during my of these tests was lessthan0.18.

PRESENTATION OF RESULTS

Thedataobtained fw thea foilsection witha double slotted flap

r

at a Reynolds number of 2.4x 10 arepresented as contoumof maxhmuu

Hft coefficient forvarious flapandfor-flappositions. These data

indicate themaxinmm section liftcoefficient thatmaybe obtained fora

given flapposition anddeflection, or thelossinmexlmum sectfon lift

coefficient thatmayresult if flappositions other thantheidesl are

selected.

Theliftcharacteristics ata Reynolds number of 6.ox 106are

presented forseveral of themorepromising double-slotted-flap configu-

pitchin~ment charac-

rations foreachairfoil section.Thesection

teristics forthesmooth condition andalsotheliftcharacteristics

forthecondition withleadi~dge rou~ss =e pesentedforthe

NACATN NO. 1545

thehighest maximum liftcoefficient at a Reynolds ‘

ood’igurattcn havi

number of 6.o x 1 Additional dataarepresented showing the lift

s

andpitchi ng+cment” characteristics of theplain alrfoll, sectfcm at

several Reynolds numbers ad thelift

~ito~nt characte-

r

istfcs at a Replds mmiber of 6.o x 1 fartheairfoil secticm witha

0.2 bhcrd spilt fhp deflected 6@. Thedatafartheplain airfoil

section W thedrfoilwitha split flap were obtained franreference 2.

~ scmacases, datafor the airfoil section witha split flapwere

available for several additional Repoldsnumbere andsrealso included.

Thefigures inwhiuhthedataem ~esented fcmeachof the airfoil

sections tested areIlsted in thefol.lowlng table $

Data

Figure

19 20

Plain airfoil and 4 8 13

27 31

split flaps

Contours of flap

28 32

5 9 14 17

b:~

position f=

cz=

18 22

Contours of fore-flap 6 .10 15

29 33

position for Ct ’25

Characteristics for 30 34

7 u 16 19 23

optimum configure

alz

b26

tia’1

ao.fJ56c fore flap.

bo.loot foreflap.

IfACA TN No. 1545

DISCUSSION

&imUIII wt

Effect of flapandfore-flap position.- Thevariation of thesection

liftcharacteristics of theflapped airfoil section as theflapposition

varies is w~marilya result of changes in theslot. shapes.A secondary

effect, resulting fromthechange in airfoil chord as theflapismoved

clpdwise, alsoexists; buttithin therangeof positions forthese tests~

thiseffect is smaU. Theideal confQirations aretherefcre theones

forwhichthebestslotshapes areformed at theflapandfor-flap

leading edges.Thedatashown on thecontours of flapandfw-flap

position indicate thatthe ideal flapandfore-flap configuration for

msxiu lift is one thatformsconverging nozzles d directs theair

overboththeflapandforeflap.

flowdowmward

Formostof theideal ccnfiguratione withthe0.07’5c foreflap, the

foreflapwas located approximately 1 percent chord forward of theslot

liparkl approximately 2 percent chord below theslotlip. Forthe

however, (fig. 6) theideal for-flap position

NACA 6~210 airfoil section, wasapproximately 1 percent chord farther forward thantheaverage.

Although thebestnosition of theforeflapforthe~CA 641-2x2 atifoil

is actually behind theslot. lip (fig. 33), little difference exists betwe= ‘–

theKaximuIII liftcoefficients obtained at the ideal position sadat the

mosition corresponding to theaverage of theothers.Theflappositions

fortheIdeal configurations varied considerably foretich of theairfoil

andflapcombinations tested, as wouldprobably be expected inasmuch as

eachairfoil section was tested withtheflapdesigned forthatairfoil.

An indication of theideal doubl~lotted–flap configurations forair-

foils andflaps .similar to those tested in thisinvestigation maybe

obtained fromthecontours of flapposition. These configurations, ho+

ever, should notbe applied to airfoil-flap combinations having shapes

add~tion, ‘m indication of the

radically different franthose tested.~

lossin maximum section liftcoefficient which maybe caused by structural

deflections of theflapor by construction errors maybe obtained from

thecontours. F@ example, in thecaseof theNACA63-210 airfoil section

(fig. 5(a) ), a depsrture of O. Olcfrcmtheideal flapposition can

decrease themaximum section liftcoefficient by as muchas 0.3. For-

mostof theoptimum configurations, theflapdeflection was 500a 55°

andthefore-flap ’deflection was 25°w 30°,although little diff&nce

existed in themaximum liftcoefficients measured forthese deflections.

lhcreasing thedeflection of thefore-flap aidsbothin forntlng a

converging slotandin directhgtheairflowdownward overtheflap.

A limitisreached In these effects, however, whenthefor-flap deflection “-

becomes highenough to cause theflowovertheuppersurface of thefore

flapitself to separate. The use of theoptimum flappositions rather

thantheideel positions in thetests whichfollowed generally resulted-in a- -

NACATN No. 1545

decrease inmaximum liftcoefficient of lessthan0.1.

Effect of fcme-f’lap chcrd.- Thedata~esentedin figures 23

and 26 showthatincreasing thefore-flap chard f!rom 0.075c to O.1OOC

inaeased themaximum sectfon liftcoefficient of’ theNACA 66-210

airfoil section by approximately 0.1at a Reynolds number of 6.ox 106.

A comparison of thedatapesentedIn figures Ill arxi 12 indicates that

decreasing thefor-flapchmd from0.075c to 0.056c reeults in a slight

decrease in themeximum section liftcoefficient of theNACA6&2C8 ai~

foilsectfon witha double slotted flap. Thedata presented in reference 3

alsoshowthatincreasing thefore-flap chord maybe beneficial in

increasing themaximun section liftcoefficient. Thefncrease inmxlmum

section liftcoefficient obtained by theuseof larwr foreflaps maybe t

attributed to a combination of theincreased srea o= thelifti&sur~ace

andbetter slotshapes.

Effect of nosition ofminimum DressWe.- The variation of c

1-

withtheposition ofminimum pressure forseveral NACA &series airfoils

of l~perce~t thiclmess is presented in fi~e 35 fora Reynolds number

of 6.0-X 10b. Datapresented inreference-2 =icate that-for airfoil

sections of thicknesses lessthanabout 0.12c, thestall usually begins

at theleading edge. !3nce thelmding-edge radllof flACA &series

airfoils decrease as theposition of m:nham pressure movesto the rear,

thistypeof stall becomes morepronounced. Thedecrease inmaximum

liftcoefficient withrearward movement of theposit~on ofminimum

pressure, shown in figure 35, is therefore probably caused principally

by thedecrease in leadi~dge radius.Forthicker airfoil sections,

wherethestall begins oversomerearpsrtof theairfoil instead of near

theleading edge, thedecrease in theleadiqpdge radius withrearward

movement of theposition ofminimum Wessure1s expected to havea

smaller effect on themaximum section liftcoefficient. TheIncrement in

section liftcoefficient caused by theaddition of thedouble elotued flap

to theNACA&seriesplain airfofl section having a mexhnum thlokness of

10 percent chord remained substantially constant (apprmc. 1.4)overbhe

rangeofminimum pressure positions tested.

Thevariation of msximum liftccef-

Effect of airfoil thlclmess.-

ftcent withairfotl thickness forthethree NACA-series airfoils tested

is shown in figure 35. Thedatain f@ure 35 showthatfm airfoil

thicknesses between 0.12c endO.@c themaximum liftcoefficients of the

plain airfoils amltheairfotls withbothsplit anddouble slotted flaps

decrease as theairfoil thickness isdecreased, slthough notall in the

samemanner.Theincrement of H;.- liftcoefficient caused by the

double slotted flapdecreases at a nearly constank rateas thethickness

isdecreased, whiletheincrement in’maximurn liftcoefficient caused by

thesplit flapdecreases as thethickness isdecreased from0.12c to O.1OC

andthenIncreases again as thethickness is further decreased to 0.08c.

NACATNNo. 1545

liftcoefficients

Datainreference 2 haveshown thatthemaximum

ofmost@oil sections decrease as theairfoil thickness is increased

of these sameairfoils

above about0.L2c although themx@nmm lifts

when equipped w$thsplit flapscontinue to increase up to a thickness

scattered datahaveshowii thatthe

as highas 0.16c or 0.18c.Rrevious

BE&mm liftcoefficients of airfoil seotlons equipped withdouble

Thedatain figure 35

slotted flaps follm theseine general trea.

extend these previous results downto a thiclamss of 0.08c.

Themsximum liftcoefficient of theNACA lklo airfoil, alsoshown

infigure 35, 1s approximately thesameas themaximum liftcoefficient

fortheNACA 641-212 afifofl sectf~.

.-Thevsrlation of ~lmum section lift

Re.sznolds number effect

allcases, coefficient withReynolds number is shown in6figure 36.

#

increasing theReynolds nuniber from 2.4 x 10 to 6.o x 1 ‘resulted

in lerge increases in themsxhmm section liftcoefficients. Increasing

theReweldsnumber &cm 6.oX 106to 9.0X 106,however, caused slight

decreases or no chenge in themaximum liftcoefficients of eachof the

airfoil sections withdouble slotted flapexcept theNACA64-21O section.

Figure 11 indicates thattheNACA64-208 section followed thesametrend

as theNACA@-210 section.

h explanation of scale effect on themaximum liftof atifoil sections

is givenInreference 4, endthisexplanation is usually applicable to

airfoils withflaps.Variations of theliftwithReynolds nuniber sre

generally apparent onlyinreglons of incipient stall(high angles of

—

attack), butfw these thinafifoil sections withdouble slotted flaps

theliftdecreases withincrease in Reynolds number in thelinear part

Thisdecrease in liftcoef-

of theliftcurve(lowangles of attack).

ficient is probably caused by changes in the flowcoalitions through the

Therefore, a new ideal confi~

slots as theReynolds number is v=ied.

ration could probably be developed at higher Reynolds numbers, and

msximum lifts might be obtained.

slightly higher

Effect of flapon engleof attack formaximum lift.- A comparison of

thedatafw thep~n airfoil sections endthatfortheairfoils with

flaps deflected shows thatthestall occurEI at a considerably lower angle

Thedeflection of a trail~dge

of attack whentheflapis deflected.

flapcauses an incre-ntal loaddistribution whichconsists of an

incremental basicloaddtstributlon endan Incremental additional load

in theangle of attack

(See reference 5.) Thedecrease

distribution.

at whichthestall occurs is attributed to thefactthattheadditional

losd, whichcomprises a lsrge partof theincremental loaddistribution,

Increases theadverse pessuregradient in thevicinity of theairfoil

leading edge; and,theref~e, thecr~tfc~~ess~e =~ient iU att~~ned ---

10 NACATNNo= 1545

at a lower angle of attack.

~dge roughn

Effect of leadi ess.- Theadditfmof standsrd roughness

to theleading edgeof theairfoil decreased themeximum liftcoef-

ficients of & theairfoil cotiigurations in sucha wsythatonlya

slight variation of msxhumliftcoefficient withposition of minlmm

(Seefig. 35.)

pressure occurred.

Themaxhnunllft coefficients of theplain airfoil andtheairfofl

wftheither of theflaps in theroughcondition, increased as the air-

foilthiclmess was increased but notso rapidly as in thesmooth con-

dition.Fa theairfoil witheither a split or a double slotted flap,

thedecrement inmaxfmum section llftcoefficient caused by leadi~

edgeroughness waslessthanthatobtained fartheplain airfoil section

wfththeexception of theNACA1410andtheNACA641-212 airfoils which

gaveslightly higher decrements withthedouble slotted flapdeflected.

A comparison of theliftcurves forthesmooth condition withthose

forthecondition withleading-edge roughness itiicates thatforthin

airfoil secthns, leti-ge roughness tends to givea lessabrupt

Thischange in the

stall thanthatobtained fa thesmooth condition.

inwhichthest&ll occurs.

t~e of stall canbe attributed to themanner

Fora smooth thinairfoil section, thestall first occurs in thevlch.ity

of theleading edge; whereas withleading-edge roughness thestall occurs

overscrew resrpertof theairfoil andprogresses forward.

Pitching Moments

Glauert hasshown in reference 6that forplain trailing-edge hinged

flaps, theincremental pltchi~mament caused by thedeflection of a

flapis a linear function of theincremental Hft coefficient. The

rather meager datain figure 37 showthatthislinear relation is

probably also true forairfoils withsplit or double slotted flaps. If

—

IAC \

theratio ~m Is calculated on thebasis of thetotal chord of

()

2 ~=o*

themodel ~iththedouble slotted flapextended, reasonably goodagreement

is shown forthedouble slotted flapandthesplit flapon these airfoil

sections. Thetotal chord withtheflapextended is equal to thesum of

theflapchard andthedistance fromtheairfoil leadlng edgeto theflap

leading edge.

Foreachof these airfoil sections equipped wj.th the double slotted

flap, an unstable breakin thepitchi

-~~ c~e (decrease in

negative pitching moment) occurs at thestall.Thisunstable break seems

to be peculiar to thedouble slotted flaps since it occurs in no casefor

theplain airfoil or fortheairfoil withthesplit flap. Theactual

NACA~ NO. 1545 IL

cause of thisphenomenon Is notclear anden analysis of pressure

distribution datawould be required to shown whatflowchenges determine

thestability of thesection at thestall.

CONCLUSIONS

Seven thinNACAairfo~l sections - theliAcA 63-210, 6L20S, 6L21o,

641-212, 65-210, 6&210,and1L1Oairfoil sections – equipped with

double slotted flaps weretested.Eachairfoil wastented-with a

double slotted flapconsisting of a 0.250-chord mainflap andOn”>

chord foreflap. ~ addition, theNACA 66-210 ai$foil & tested witha

O.10&chmdforeflapendtheNACA64-208 airfoil wastested witha

O.@&chordforeflap. Theresults of thetests provided the”foilowi”ng “--“

conclusions $

1. Theoptimun foreflappositions forthesedrfoflsweregenerally

about 1 percent chord forwerd and2 percent chcmd below theslotlip.

Theopttmum flappositions vexled considerably. Thedeflect~ons fcw

whichthehighest mximum liftcoeff~cients weremeasured wereabout

50°to 55°fortheflapandabout 25 to 30°fcmtheforeflap.

2. For thedrfoil section witheither a splft or double slotted

flap, themazimum section liftcoefficient decreased as theposition

of mim pressure wasmovedto thereerendas theairfoil thiclmess

wasdecreased to 0.08chord.

themaximum section llftcoefficient increased

3. ha cases,

appreciably as theReynolds number was increased from2.4x 106to

6.ox 106butgenerally decreased slightly or remained constant as the

Reynolds number was increased from6.ox 106to 9.0x 106.

4. ficreasing thefor-flapchord provided increases in themaximum

section liftcoefficients of theNACA64-208 andtheNACA6S210 airfoil

sections withdbuble slotted flaps.

‘j. Theaddition of standerd roughness to theleadlng edges of

theairfoils equipped withdouble slotted flaps caused decretints in

maximum li’ft coefficient thatweregenerally slightly lessthanthose

withflaps retracted, caused a decrease in thevariation of mmximurn lift

coefficient withposition of minimum pressure andwithairfoil thickness,

andcaused thestalls tobe lessabrupt thanthose fortheairfoil in the

smooth condition.

—

NACA~ flO* 1545

6. Theratioof Increment of section pitching+muent coefficient

to increment of section lift coefficient at a section angle of attack

%

.-

ACm ‘

Of 0° — based on thetotal chord of theairfoil withthe

()

.&2

%=00

double slotted flapexterxied wasapproximately thesameas thatobtained

fortheairfoil withthesplit flap.

7. Anunstatle pitchi~ nt breekis encountered at thestall

foreachof theairfoils whenequipped withthedouble slotted flaps

endseems to be. peculiar to dou%le slotted flaps.

Iangle~hkmarlal Aeronautical Laboratory

National Advisory Committee forAeronautics

-eyFie~d~ Va.November 5, 1947.

lwFERENcEs

Wind-Tunnel hvestfgation of Four

1. CSMll, Jones F.: Tw&Dhensional

65-210 Airfoil Section.

~es of HQ&Lfft Flap on an NACA

NACATN No.1191, 1947.

Albert E.,andStivers, Louis S., Jr.x

2. Abbott, TraH.,vonDoenhoff, 1945.

Summary ofAirfotl Data. NACAACRNo.Lx@,

3. Braslow, Albert L.,andL&tin,Laurence K., Jr.: Two-Dimensional

Wind-Tunnel Investigation of an Approximately lh-l?e&cenWI%ick

NACA 66+krie*e Airfoil Section witha Double Slotted Flap.

NACATN MO. 1110, lg46.

4. Jacobs, Eastman N.,andSherman, Albert:Airfoil Section

Characteristics as Mfectedby Variations of theRemoldstiber.

NACARep.No.586,1937.

of theChordtise LaadDistribution

5. Allen, H. Julian:Calculation

overAirfoil sections tith Plain, Split, or SerialJy Hfnged

Traikh@Uige Flaps.NACARep.No.634,1938.

6. G1.auert, II.:Theoretical Relationships foran Aerofoil with Hinged

Flap. R.& M. No.1035, ~itishA.R.C., 1927.

NACA TN N~. 1545 ‘

# TASIE1 Tmr!s 2 osmmmd FOR NAOA 65-so ‘MRFOIL ORDINATES FOR NAIYA 63-210 AIFWOIL upper surfaoe Kemr surfaae Station Irdlnnt(

3tat10n )rdlnate

0.530 t 1 I L.E.radlua$ 0.68’?

L.E.radius z 0.770 Slopeof raMus throu@. L.B. t O.@k I

Slopeof radluntlmOu* L-E. $ f3.~4

— l i ORDINARIES FOR NAOA lk10 AIRFOIL — Loweruurfaue Upper summa Stat ion Ordinate Station Ordinate o I o 0 I o .

1.10 L.E.radiun; slopeof radius throux L.E. t 0.05 NATIONAL AOVISORY CONNITTE3 FM USONAVTKS -, —.

-—- ~m 90RIIMA 6)+-210 A12FXL Igper surrane Lnar 81UZ?.90* —_ )tatlonIroimte atatim Itatlm I.E. lmlins. 0.4

.x. IS 0: 1.04

low & lmo.itu 6 lqm Of MU!mti al IA.: O.ctu II

NACA TN No. 1545

Atifoll chordline .- ,1.~’-l.- “-” “ TAS1259 TAsL28 FLU ORDISAm FOR65-210 AIRFOIL FLU OFOINAT%S FOR 63-210 AIRFOIL ~tattons andordinates given frm rmp J@tlons @ ordln.tea given frauf .4 ahordlinein peroent d rfoll ohox@ chordltiain peroent alrfoll daor i Lewer aumfa- kmer mrraoe Wpper surfaoe Up,per surfaoe

I

I stationOrdlntte StationI Ordinate station ordinate stat ion O.vdlnate o 1 [ J ! t L.E. rsdiuat 0.800 L.g~r~~&eaenterz O.~0 above rlap L.E. radius 0.562 s, L.~iOMymoatOrz 0.201 *OVO fhp DimemlOn8S O.lm _.

Dimension at 0.200 .— .

TAsm 10 mm 11 — W ORDTKA~ FoR lhO AIRFOIL FLAP ORDISA ~ FOR6&-210 AIRFOIL

%’s%%:di?’%i%:% 2RW%S’?

Lowermrfaoe Upper*urfaoe I n+. *4 en IOrdirmta Station [Ordlaate —

0:;2

1.00 2.00 i:% 2:% g:a& 9.00 10.CQ 12.oo .

1 .00 ? I .m 21.00 Z&00 25.00 . , t L.E.

L.!S. radius%1.207 LE.

L.B.radiu oenterl0.295about rlap Oho md Mne chor~line

Dlnmr-. . 19’! on -! 0.7W I

mnenaiona, 0.752

L

— -— NATIONAL ADVISO$W COMITTEE FM AERONAUTS . —

!s

Airfoil obrd M.

--l

--- mm K mu 13 mmE Llt RAP -h= FOR6&210 AIFS02L PIAP Ommm FOR &l-212 UmUL mnr mu.fmo Statiw L.Z.Wuxz O.&0 L.E&l.i.iea@nrs 0.1?0 .tave flap Dlmn.ion m: 0.200

--J

ii 1., #

, I

TADU 16 TM’L’ 17 O131kA~ FOR 0.056 -CiWLO FUFS PUP orum+mg FOR o.loo-oHom mm pm &tat lms and ordinates given frm @tation.s and ordlmten g.tvm rrm

@ions and ordlmt.. glvm frcm

fore-flap moral llna Jn p.moenr fore-rlup ohcwdMm in pemuont fore-flap ahordMm n pelment alrfoll Ohurd_ airfoil chord airfoil ohm d L,E. radius; 1.20 [on chord Mm) MAT10t4u UMSDRY CoHmTm m hEamliTK5 , .,, .1.’ -..

—.

-= -..

?~ ,, .,.

e 63-2M &l@lo 65-210 btim .’ lwa 1’ 1’ I

NACA TN No. 1545 L

(a) Airfoil Mth flap.

Y2

t

~

‘2 — — Variables ueeclto deftie flap COnfiWat~OnfJ. .

(b) NATIONAL ADVISORY CO)MITTEE FOE AERONAUTICS .

Fi@arex?.- TgpLoal airfoiland flap configuration.

NACA TN Ifo. 1545

20, .

t--’-”””c~

“ -- d .

NATIONAL ADVISORY .

COMMITTEE FOR AERONAUTICS .

Figure 3 .- Profiles 6f the” threefore flaps tested

in combination with 0.2~Ocslotted flaps.

r * ‘ ,

H

z

2“7zEmIIn

z

p

-. 2 ?+

$

c) NATIUIAL AoWWFIV Qwm122mthmmrmcs

D

if [b)‘Airfoil dth relit fllP. of = 600.

~ seotim Mft and pitahims+camt otwmotorfitlom of tho IIACA6340 tifbfl saotim WIChd timut a O.2~ BPlit ~um L.- rlnp .

i I

I ‘, II .’

. — .- .-. .- @ Optilmm P,ltic+l h 3 2 1 o-l= IZ, wrc*nt c \ ‘\ .

\\ \ \..

(.) 6* = p% am = 25?

I

, , h h

*

1, l., !

&l Optimm psltian 2:30

I \

J4

\ -\ “4 3 2 1 0-1 .

ye, pnrcmi c \ \\ \ \

Cn

y

&

O&

-T .

210 -1 -2 mrcent c \ \ \\ \

‘\

(n

a

,, ,, , , % P ,,.

:,!, I ,*

‘ii

d“

I

contouw M fhp ad fore-flw Wsition for mukm lift of tbnHAOA 6W1O tirfoil motion with I dmble slotted m- 6.- flaPI 0.W/5s farm fhP; 0.25Cb fhP.

q = 5@l J+f =30”; R =2.4 .10$.

:, I .- -..

I

3.2 2.8 2.8 .?.h .4 ~ : .

1 1 I : i 2.0 : 2.0 * ~ ,6 I x I L ~ g 1.2 ~ a a .8 ‘.a .4 -4 ‘a -16 -8 0 8 16.

Xl = 2.30;71= 1.78; ~ ..2 (a) off .2P; Of =5@.

X2 - 2.17;T2 = 1.23.

% .

z

b $-.

g’

z

a

; ““6 D

~

z

m

~

. -.

84 -U -8 0 8 16

(+

Omtlouan’la of *ttmk, ~, d,g UATIOIIU AWGOAY (b)Fi=6.O XII+, ~“~~ *ocion lIfo- pltuhing+coen t dmrmtorl-ties M tboWA 63-210 drfoil saotion with a doubh dukted flcp.

w=~ 7.- o.~o rora flql; 0.2303 rlsp.

o

** r * .

Eaatlon mgh or at-k, QU, W (.) Phbl *foil, WnaLu Amsom 2un’rmm Kxa4m.6 -.

atotiw ULS20 of at-ok, EO, b6 (b) A&roll tith mpllt flql: .+ = 60”, .— .- . .-

.%’

— 1.39 II- I I (a] 6f = by; Om = 20’?

Pi@ma9.. C.ant.xm cu flap PX1 tion ror uxti l!ft d tlm IIACA &2Cd l lrfoll motion with m double slottta rlq; 0.07% fOPO f~P; 0.25@I CM. B = 2.4 x lb.

, , -.

\ \\ \ P / i .

1-

‘7-

“1

@ out-m Foelti.nl . .

I ,, i, ,, I , l ,

I

* .

—

+ w p--

--l

l-l ‘\.

h

@ c@Jmlm POaition 765 b5210-I \ x~, mrmnt c \ \ \ \\ \ g \ (d) bf =k5°; Ofr=jOO.

1+

Fl@.a 9 .- Omttiti.

o

a)c&

,, il I ,,

;, i“

I -— -.

c30Ptlmm PO.,,,..

XZ. r+rcenc o \\ \ \ \ .

\\ \ (.) af= po; 5rr= 30”.

F%ZUW ? .- COntlmmd.

I

* .

, , .

(r) of= 55°;Off= 30°- rlgwo 9 . . Olmolwbd.

w w

i i ‘ i ~

.75

r

\ rk~. 10. - Cmtonr. of flapand fom-fhp FQ#it ion for ‘mxk.a lirt or tlu HACA 61@c9 .IIYO1l sect ICLI @th l doubl. slotted rkp; o.q50 rm nag: o.z5knap.

% ‘k5°1 brf‘25°; R =2.14 x u$.

. .

Y b, ,,, ,,

I

I , , , 2.8 Ida] .- o

‘@_JmHid

z

8 26 .16 -El o

g

&otlc’il lngl* or attmk, %, dog

D

(b)

‘?’

Sootlrm N121d or •tt~-, 5, (n) am=@; q=l.l@; yl=l.88; R=6.0xw5.

36 NACA TN No. 1545

64-208 ---

NATIONAL ADVISORY

-~L 8 16

-16 -8 0

COMMITTEE FORAERONAUTICS

g

Section angle of attack,

a.s de

Fi.gUre 12. - Section lift and pitching-moment characteristlce

——

or the NACA 64-208 airfoil section witha double slotted

uff = 250; flap; 0.056c fore flap; 0.250c rl~p.

bf = 500; = 147; Y1 = 2*36; X2 = 197~: Y2= 1941;

‘i

R=6.OX1O.

I e ,# .

El

Z.11

z

p

2.0 1.6 1.2 .8

.4

0 0

2,0 x 106

2:!

standard roustwsn

z

smtion nn@e af l ttmokj ~, dog

D

(a) Plain l irfoil.

D NATIONAL ADVISORY COHHrllum UwA4mcS -. 4 8 16 -16 -0 0 &OtlOn l ngle of atta*, ~, f19g (b) Alrfoll wl tbspilt flap. 6f= 6oo.

Flguru 13. - — Seotlon Mft l nd pitohing-mment oharmteristloaf::pha NA.CA 6I+-21o akfoflieot.ion with andwithout a 0.200 split

I

o

II t I

1, ,, gl C@hn pomltkm

“654321 O. 1-2 \

*2, prcent c

\

\\

\

““(j

CmtiW, c.f fhp p.itim rem -m lift of b UffiA 6&10 l irfoil sOCtlOn rlth E don~. d.ttud tiP; rl@w llb- K = z.~x 10$.

0.0750 fOrO rw; 0.2500 m.UP.

t 1.

I I ,1, ,, 5 k 3 2. 1 0 -1-2 X2, Fdrcent n \“ \ \ .

\ \ \\ F=’) Bf= w”; Off= xl”.

w CD . .

.—

z

D

o

, * .

“hlax

2. ~ \ ;1 ?!

:2 m / t ~ 5’ I 4 3 2. 1 0-1 XI, percent c 2.

NATK.W. NMSIMJY ~ comlTEER9~ t

I

Oontmm or flap ad rore-rlql Pc.sitilm ror MMmu lifk or me UACA61@20 lli-fd,l ,eeblon tin) c dalble slotted pm 15. - fm; ~.0750 fm fm; o.ajm f~p. br=~o! Cyf=%f’; R= 2.4x1&.

o

i. , ,1 :, I

. .- 3.2 5.2 2.8 2.8 2++ 2JI 2.0 2.0 1.6 1.6 .

1.2 1.2 .8 .8 .b .4 o 0 0+-Z6”~08M 2wtllmm21* ormttmk, ~, bs

z

(a)IJ~r = 25°: q -1,18: J,= 1.91: E = 6.0 x 106.

Xl = 1.23: 71 * “ 5!P.

%

= 2.32; ~ = 0,56.

2AT12+ML lRlsoQy cmul122Fa~Q

a)

~

2’

N

-.8 0 8 Z6z

-4-264

I

1, ‘1, , * , .

2’

& m ,.

“21 O-2-2

percmt c =2, Iwmlul Kw20RY a+HlTE2Rl Maw—rKs \ \ \ \\ .

lugurm 1’/..

Omti.um M nmp WItithI f w Mdmm Urt a tb HAOA 65-so won .wJti.n withs do~h .1OWC4 flap J o.0750 fernflw; 0.2500 f-.

bf = WI off= 25°; R = 24 x 206.

1 1 ‘1

1:., 1 ‘ii

z

D

P1.@d 28. - O.mbour# or Clap srd fore-flap pneithn fcm ~tm llft of tie UiCA 65-ZIO ~Irfdl mc.tion mtth a dorble slot* flap; o.q5a fore rmp : o.250n rl.u .

of = 5@; off = 25°; R = 2.4 x d.

,, , , l ,,!1. I .

# 2.8 2 2!4 2 R 2.0 2 1.6 1.6 1.2 1.2 .8 .8 A .4 o 0 0 -.

-. 4 k -8 0 0 26 Seotian M@ of ~ttmk ao, tiE (,) plain uil.foil, -4 -. 8 +$-808 -16 .8 0 8 [o) MrfoAlfith .OouMa dotted -P; 0.2% f11P; Oa’pjdfom imp; off . w; of = w; XI = o.921 71 - 2.3i; ~ = 2.501 r2 = 1.10, I I .- -M-2 o 8 (b) M=oll wltbWit fbP; 6r = 60°; E = 6.o x l@.

-— .

I ,8 .

,,,, # .

@ O@imuaK.M.itlan (I] of= 50°; am -25°.

I I i ,1 !.l, @ C9thvi Po3itioo “65i!3210-1~ -3-k \ x~, percent c l \“

z

IUTIO!UL MW$OEY ...

u#rmTEFm Afxawm ““\ \.. ‘1 ‘\ ‘\ t, , (b) 5r = 5901 aff= 250.

Fl@re21.- Cmtlnwd.

‘,, ,, ,=, l .,.

I ,. :,,,,, ,:,; ,,,’ L, 1;1 ,il: ‘il. ,,, , II ,“’ -.

, .

, I N“ ‘\.

- \

“8765 ~3210 ‘l~\ x~, per..nt c \

S

o

\ .

D

\\ \ :.

I I :’ (s) Of = Wo; aff =’ ion.

I L “i H* 2/ .- Contfn .

1, I :i ~i ;1 ,: I ‘1”l. J :’ 1,, ; )J ,,, ,.

.- — — —————— \ \\ \ , ., , .

, .

, * . .

“ -.

(b) E = 6.0 X lti.

!’ -1 , 0 , .

, -% 0-

—2,ul- 7

A

\/ ?

(, / \y r- “2 , k- - I 1 — -+-

z

d—uu_uJ \

D

“6

5k3210-1 ~-3

o

x~, mrmnt c

D

\ \ \\\ (d 8f q 55’3] aff= 29”.

P@um 214. - Contuim of fti pmhiad for mxlmm lift cf tk YAOA 6Az1oulrroll #cation rlm s dmble810kM fW o R = 2.tj X M6.

O.lCOO fora flw; 0.2900 nap.

ill, . .

..-.

KS \\ \

o

“ .

. , w IL I

II

.-.

I .

, , , l .k.

I I I I f I I 5)

z

XZ. p.rmnt c \ \ \ \ I \\ \ Off = 3@, CUWIULW.

l 1 \ :,. ! ‘, .- \< NATIOUU Amlscw amm m Mkv4um2 \ FeO 25.. Contoulw d nap and f.m.fl.p pmitlo~ fm. ~ lMt of tho dACA 66-ZIO slxfoil motion mlth a donbla dotted flap; 0.1000 fore flw; 0.2540 flap.

% “ 55°;off= ?QOJ R = 2.hx u$.

, .

I , ,

(ad (%

ftom%’’%”l -aL .16-E o au

-” motion q.in M attu.k, ~, @

(b) R=6.0x Ic$, , K Lo .

I I I I I I I I I I I E .

Olbl V!IVN

gb131 ‘oN NIL VCWN 8’3

—

I .

4u8r

l-i-

‘ F\\

-1 \ @ Optlmm pc.nitim \ XZ, pert.nt e \\ MTmul Mwsony \ annn=m~

\ z

D

o

\ \\

D

(d af = 50°; off = 25?

— FiSIM ~.- Oontoura if flap pes!tion for muiaun llCt of ths NMA lk10 Sirfoll aaatlon rlth a tibln alutted rl.np; u = 2.4 x Id, O.q% fOt% fhpj 0.250C flw.

I -+ 1.18P 1 “-r \ NATlaiAL~ Ccwmm m KmmTlcc peraent c \ \.

“(’

\

\ \\ .

. .

1’1 1 I * —

~ 1.23

1-

1 -r ~ Optlraun position ..- X2, percent c \ \

z

. D

o

\ P

—

-P

—

(0) af =50’=’; 6rf =30’?

FIWO 28. - Conolwhd.

i

x,, por.amt c k----2.a3— ‘-4-

z

D

c1

D

F p-o 29.- contima CU flar ma fom-rMp PoniiIion f or ~ lMb M tboUCA LQO atirou motiontitba double .lottcd” fw; 0.q5c foro flap; o.2500 *. 8f- 5y; OH = 25°1 R= 2.4X 106.

. .

, .

.“

i , -’i

I

....,.,, 1 e P ?

El

z

gi

&

I’P o-l (~) 6rr =25°; af =50°.Xl=l.~;~1=l~~; (b) $fi = 30°; Xl=1.23; yl q l.n; q 2.54; 72 = 1.56.

X2 R = 6.0 x 106, UN- AOvlSmY clwtmEia AmwTuS

m

ULuu_uJ o

-a -~6 ..8 0

‘ 2ootion mglo of attmok$ %, % (0) 5ff =25°; XI=l.~;71 =l.~; R=6.o X1~.

Iugure yl .- S.aotion llft md pltding-mmnt ohxrmterlatios of th NACA l@.Oairfoil aeotion with l doublo slotted flap; 0.075a fore imp; o.25w fhP.

!’ 1”:

.! I

, .

H

z

p

@lcQt2Bm p.mlblcal

z

‘f65b3210~~ ‘3 RZ, pwaml e

D

\ \

c1

D

\\ \ ., [a) et =L50: off =2>.

.. . .

cm 1, .

a .

:, , .

, 1’ :

d

-\.

Q ‘\

nrrlowu MMm

CC+HTTU m ~Ks @ Optilmm position I I 1 1 \ I I I

\ b~

765 b3210-1 4 1~, percent c \\ \ {.) af =55°; aff =25?

H&-dM 32.- c0nt5nue4.

1’

I

I I 1 I I I l\ 1 I 65 b3210 -1+ ‘3 x*, percenb c \ ‘/ \ N4rmu mm \ aumnlEEFmmuMJrD .

\ \ \

m

l .

l , # @ optimu position (.) r+= 50”; arf= 50°.

Fl~ 32.- Cmtinwd.

I

I ~, 1, ,,11 . ,.. ,.

2!

-1

g) OptlmmMsitlon

3 NM AOVISORY

E~AEROMWICS

II

7 6 5 4 3 2 1 o-I-2

\

X2, percent c \ \

z

D

\ \ \ .

\/ \

-1 z

(r) 6f =55°; off =30:

N?

FlgurO U.- Continued.

l , ,1 [ ,.

I * , a , .

El

z

o .

!$

llATlOKU AWISWIY mll’iz FMMkwLmcs 6543210 -1-2

z

D

o

D

. . .

(8) bf = 60°; Ev = 30°.

., Fiwo 3-? ,- Cn+l”&& I ~,, ,’ ~ ,,, ;, , I 1, ,1”” ,“ .

1 ~“:1’ ““ i,, ,./ ; , ,

,1,’,’”;: , i] “

I 1, ‘1 1,11. ! J < ,:

1’J.. 1.1,!. ” I ‘ - ~

— Contotuw of flap and fore-flmp POwibica for _xlm.u IJft of tha ilAOAU1-2U a2rfoi2 pm. 33. - mntlon tlths dcnbla *lotWd Clm; o,o’(~o fore rlq; 0.2* tip.

br . yJO; Orr = q~; R = 2.4 ~ ld.

. s I .

l a’ 1 , ,

in

# am= 300; 8* = @. q = O.*; ~ = 1.g2; -.2 .

X2 = 2.lo; 72 = 1.96!

; 71 = 1.92 I u = 6.0x x$.

(.) Off “ Yf;~ = 0.98; Fi2nre 34.- MotionlMt ud pltotdngant -.?torlstiez oftha UACA 6hL-21.2 ~IIVOiI Soetion with I doobl* sl.ottea i’UPJ Cu 0.0-755- rml O.WM rm.

— Mcmtll

-—-— Stsndud lvDgIBynm /

4!!1!1!

I I I I I I ! I I 1 I 1

llllld

o .1 .2 .3 .IL .S .6 .7

POBltim of n lam plmawo, X/a

xuimlm tiicko.ss, Z/c

[a) vu.imthri of ok= with p Mica or minimm p?omlnw ; : = 0,10.

., *

z’

3. ..

\ \

z

< o ‘\ .

Double slotted flw.

~ -.1 ‘ “> \ 2.

with 0.0750 fore flap — Sput rlap \ ‘i-t-rkr : ! 2“ .-

i“

.LJ—J—LJ L++++#J

--- o .IL .8... 2.8 x 16 Inorament of oeotlon Mrt ocofriolmt, b; Rsynnlds ntiar, B Vu’laticm of Wreatnt of Seotlm lit-t OoOfflOiOnt m ~7-- tith tamcamnt a? motion pltohing~ Ooafrtiient Oausd by addition or flaps on mm w HffiA 6-HerIoB airr.il

motions. a. m 00. 1

1, :., ,, ‘1 ,, I

Overview