Bidwell, Jerold M

Cahill, Jones F

English

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RM L9J03 
RESEARCH MEMORANDUM 
SURVEY OF TWO-DIMEXSIONAL DATA ON PITCHING-MOMENT 
CHANGES NEAR " U M  LIFT CAUSED BY DEFLECTION 
OF HIGH-LIFT DEVICES 
By Jerold M. Bidwell and Jones F. Cahi l l  
NATIONAL ADVISORY COMMITTEE 
FOR AERONAUTICS 
WASHINGTON 
December 2, 1949 
https://ntrs.nasa.gov/search.jsp?R=19930086004 2020-06-17T16:13:34+00:00Z
By Jerold M. Bidnell asd Jones 3’. C a h i l l  
The large pitchin-t. increrments associated w i t h  deflection of 
certain  types of t r a i l m d g e  high-lift devices have made it d i f f i cu l t  
o r  Impossible t o  obtain trim during land- and take-off. As an aid in 
the selection of hi&-lift devices, therefore, a survey has been made 
of two-dimensional data on trim changes new maximum l i f t  resulting 
from deflection of various tspee of lead-dge and trailing-edge high- 
lift devices. Increments of pitc-t coeffician-t; near maximum 
lift caused by deflection of trail-dge high-lift devices &en 
plotted againet Increments of.maximumlift coefficient have been found 
t o  f a l l  within a fairly mow band, regx&Less of such variables as 
flap size o r  airfoil section. Trail-dge devices which prwide as 
increase in airfoil area produce much larger pitc-t increments 
than devices which merely increase the a i r f o i l  cariber. The addition of 
l e a d i n v d g e  hi&-lift devices, and particularly those lead-ge 
devices which extend to caum an increase ln mea, cawe Urge reduc- 
tions in the   p i t ch iwoment  increments caused by t ra i l lnvdge- f lap  
deflection. The me of extensible leading-edge devlces with mexben- 
s i b l e   t r a i l i n e d g e  devices seama t o  offer the best combinatian of hi@ 
lift and low pitching-mcanent increments. 
The large pitchin-nt lzkxemmts associated with deflection of 
certain  types of trail€ng-edge hlgh-lift devices have made it d i f f i cu l t  
or impossible to obtain trim during landing and taksoff. Although 
‘other factors such a6 ground effect influence trFm, a comparison of the 
pitchin-t increments tha t  result f r o m  deflectian of various hi&- 
l i f t  devices 2s useful to obtain the optimum f l ap  ‘;me. 
2 ." . - IQACA RM LgJ03 
A survey ha8 been made of twc-dhwmianal data on pitching+mmmt 
change~l  result- fram deflectim of high-lifhievices.  Data are 
presented.for vssious  types of both  1eading-edge.and trailinedge 
devices  which are in general use. A cmpilation is  presented in 
reference 1 of data an airfoils  equipped  with  various " p e s  of trail- 
ed.ge high-lift devices. The pitchin-t data cmidered Fn refe? 
ence 1, however, w e r e  those  near.zero angle of attack. Due to the  fact 
that pitch-t curyes. f o r  .airfoils with high-lift  devices a r e  not 
generally linear, the  pitching m m t s  near zero lift may not be a good 
indication of' the magnitudemof  pitching  moments at hi@ lift coeffl- 
cients. The present analysis is  therefore  concerned only with  pitch- 
moments in the  region of maximum lift. 
SYMBOIS 
neaz-mximum section  lift  coefficient 
section pitchinvment coefficient  about aerodpamic center 
of fl-apped airnil f o r  ne" lift  coefficient . 
esg le  of attack  for ne- sectian  lift  coefficient, 
degreee . 
angle' of deflection of trail-ge flap, degrees; positive 
when trailing edge is down 
increment in nem+mximum section  lift  coefficient  caused 
by  deflection of high-lift  devices 
increment Fn section  pitching+nanent  coefficient  at n e e  
maximum section  lift  coefficient  caused by deflection  of 
high-lift  devices  measured about aerpasnamic  center of 
plain  rfoil " . 
chordwioe  position of aerodyaamic center,  percent  chord; 
positive  when  aerodynamic  center  is to-rear of leading 
edge 
podtion of aeroaynamic  center n o m  to chord llne, 
percent  chord;  positive  loc&tims are below chord  line 
Y 
. NACA RM L9JO3 3 
Sketches of the  various types of high-lift  devices  treated in t h i s  
paper are shown in figure 1. Ih figure 2, increments of pitchi- 
mamant coefficient about the plain-irf'oil aerodynamic center have been 
plotted against increments of lift coefficient caused by deflection of 
various types of high-lift devices. The high-lift devices were at the 
p o s i t i m  and deflection for .the highest maximum lift coefficient. &e 
data ahown in this figure are for a lift coefficient near lift 
but  before any large change in  pitching moment has resulted from the 
stall. Ln all cases  this  lift coefficient is greater than 90 percent 
of  the maximum l i f t  coefficient. Curves have bean drawn In th i s   f igure  
t o  show the general trends of the data presented but are not intended 
t o  indicate a precise variatian in these variables. In order t o  provide 
more detailed Information on these configurations, a l l  the data pre- 
sented in figure 2 are l i e t ed  in table I along w i t h  the sizes of hi@- 
lift devices used and references t o  the papers in wkich the data were 
originally presented. It must be realized that the pitchin-t 
data shown in figure 2 cannot be applied  dlrectly t o  finit" wings 
but that they aSe shown herein merely as  an indicatian of the re la t ive  
merits of the various "pes  of hi&-lif% devices aa far aa their effect 
on section lif't and pitch-t changes is concerned. IIJhe effect  
of using'different types of devices 011 different portion6 of the a 
span in particular cannot b8 shown by these data but may be inferred 
since the characteristics of the complete wing are derived frcsn a 
summation of the  characterist ics of >he m i o u s  sections along the span. 
As ahown by the data fn figure 2, the pitch-t increments 
caused by trailin" Ugh-lift devices which do not  increase  the 
wing area f a l l  within a f a i r l y  narrow, well-defined band regardlees of 
such variables as f l ap  s i z e  o r  a i r f o i l  section. (Data f o r  those single 
slotted  f laps with ahort  dot-lip extensions are included in this group 
.since they produce anly s x d l  increases Fn area.) These data differ. 
from the data shown in  reference I f o r  conditicme near zero angle of 
attack. The data in reference 1 &ow that ,  at the law angles of at-tack, 
the pitchinwament  data agree fairly w e l l  with  thin-airfoi l  theory and 
that large moment changes occur as the fla- r a t i o  is mid.. The 
data &own in figure 2 for nem+mxilnum lift tqdicate higher ne@ative 
pi tchinwoment   increpqts  Fn. all cases than the data at  lower angles 
of attack. 
&e data f o r  trail- devices that increase area are  also 
shown t o  f a l l  within a fairly well-defined band althou&  devices of 
t h i s  tspe cause much lasger  increases in pitching m.oment f o r  a given 
increase in lift coefficient than the devices which do n o t  increase 
area. This result could readily be anticipated since the increase in 
4 
area result ing f r o m  Sxtemian bf these devices is far behind the  center 
of mormnts. T r a i l m d g e  devicee. of this type can produce larger  
increases in maxFmum lift than the devices which do n o t  increase  mea 
but do so at the expense of much greater pitching momsnte. 
.- 
Leadinedge devices  increaee mimum liftcoefficiazlts  prihci-  - . .. 
pal ly  by delaying separation o f - the  flow and therefore cause l i t t l e  
change in pitching m t s  Extensible leadinvdge devices, because 
of the f a c t  tht the locat-lm of the high leadrzlg-edge load i s  moved 
forward, can act- decrease the negative  pitching moments while 
increas- maximum lif'ts. As shown in figure 2, however, the Increases 
in mElxFrrmm l i f t  produced by leading-edge devices alone are re lat ively 
amall. L e a d w d g e  high-lift devices also cause the maxFmum lift t o  
occur at higher angles of attack, which r e s t r i c t s  t h e i r  use in same 
applicatims. " 
.. 
? -  
When l e a d m d g e  devices axe used in.conjunction  with trail- 
edge devices the advantages of both the t r a i l w g e  increase in 
camber and the l e a d m d g e  delay in sepration are obtained. The 
pitchin@noment increments raail t . ing f r o m  auch combinations with no 
increase in area are of-verg nearly the  same magnitude as those for   the  
trailinege devices alone. Data axe shown f o r  only one combination 
f o r  w h i c h  the tmillng+xlge device extends but  the leading edge does not 
extend. The pitch-t increment f o r  this configuraticm shows a 
definite decrease remlting framthe me of' the leading-edge devices. 
When a l e a d w d g e  device is eXtendeQ,. decreases in negative 
pitching moment result because a k g e  portion of' the load is c m i e d  
forward of the normal a i r f o i l  leading edge. .Egtensible l e a d i w d g e  
devices in codzbFntttion wfth either extensible or nonextensible trail- 
edge devices are readily seen t u  provide the largest increments in - 
maximnu lift o f  any of the devices considered. If extans ib le  leaa ine  
edge devices are added t o   a i r f o i l s  with nonextensible t r a i l i n v d g e  
devicee, increams in l i f t  increments occur with reductions in p i t c h i n e  
moment  increments. (Compaze configurations 5 wl'th 8 and 13 with 15, 
table I. ) l3' extensible lead invdge  devic-ea are added . to a i r fo i l s  
w i t h  extensible traillng-edge devices, however, increases in maximum 
l if ts  alone occur with l i t t l e  reduction in pitch-nt incrementa. 
(Compare canfigurations 33 with 35 and 36, t ab le  I. ) For this reason, 
extensible l e a d m d g e  devices combined with nanextensible trailine 
edge devsces seem t o  offer the best- canibinatim of high lift and 
moderate pitchin-nt Fncrements. . . . 
tils an a id  in the  application of section data on high-lift devices 
t o   t h e  camputation of finite-span w i n g  characterist ics,   detailed infor- 
mation m the nearrnaximum lift coefficients, aa.@es of attack a t  which - 
they occur, aerodynamic4enter positions, a id  the p i t c h i n v m e n t  ' 
coef'flcients about the aeroiiynamic center  for a number of high-lLft 
c 
NACA RM LgJ03 5 . 
L 
devices at vazioua defl'ectims are shown in figure 3- The variations 
of pitchin-t coefficient nlth l i f t  coefficient for a i r f o i l  
sections with high-lift aevices are not generally linear so that an 
exact aerodynamic-cmter poeition covertug caniiitiom throughout the 
entire lift range does not exist .  The aerodpmic-center posit lam 
. sham in figure 3 were coquted by the method of reference 2'8 for cm- 
di t ions that exist near maxFmLun lift but apply through a range of lift 
coefficient of about 0.8 below cz* . 
A compilation has beeQ'ma.de of a large apmunt of two-dimsneional 
data on trim changes ne= maximum lift result ing from deflection of 
various of high-lift devicee.  Bcraments of pitchin-t 
coefffcient near maxFmwn lift caused by deflection of trailing-dge 
high-lift devices when plotted against increments in maximum l i f t  
coefficient have been found t o  .fall within a fairly narrow band., 
edge devices whfch prwfde an increase in airfoil area produce mch 
higher sitch-t incremante than device6 which merely increase 
the a i r f o i l  camber. The additim of leadinvdge high-lift devices, 
a d  particularly those leadinwdge devices which extend t o  cause an 
increase Fn area, came large reductions in the pitch-nt incre- 
ments caused by t r a i 1 i n ~ e " f l a p   d e f l e c t i m .  The use of extemible 
leadinedge devices with nonextansible t ra i l invdge  devices seem t o  
offer  the best combination of high lift and low p i t c h i n w n t  
increment s . 
' regardless of such variables as f l ap  s i z e  o r  airfoil sec t im.  %ail* 
Langley Aeronautical Labo.rat0z-y 
National Advisorg Committee f o r  Aeronautics 
Langley A i r  Force Base, Va. 
6 .. . . . . .. - . . . NACA Rbf L9J03 
. 
1. C a h i l l ,  Jams I?. : Shmmary of Section Data an Traili&Edge =&- 
Uft Device8 .' NACA RM L8DO9, 1948. 
2. W e n z i n g e r ,  Carl J., and Eamis, 17hcanas A. : Wind-Ipunnel 
Inveetigatim of an B.A.C.A. 23012 A i r f o i l  with V a r i o u s  
Arrangements of Slotted Flaps. RAGA Rep. 664, 1939. 
3. A b b o t t ,  e a  H., asd eeenberg, m: Tests in the V a r i a b l e -  
mity wind o f t h e  N.A.C.A. 23012 Ai r fo i l  with plain 
and Split Flaps. W A  Rep. 661, 1939. 
4. mein, Milton M.: Pressure D i s t r i b u t i o n s  and Force Tests of 89 
mACA 65410 A i r f o i l  Section with a 5O+ercant-Chord Flap. 
W A  !IN 1167, 1947. 
5 .  Wemjnger, Carl J., and Hkmier, Thm A. : WindJTmnel 
lhvestigatian of R.A.C.A. 23012, 230Z?lj and 23030 A i r f o i l s  with 
Various Sizes of Split Flap. NACA Rep. 668, 1939. 
6. Schuldenfrei, "vin J.: WWdJTurmel Lnveetigation of an 
NAGA 23012 A i r f o i l  with a Handley Page Slat and Two Flap 
Arrangaments. I&I.CA ARR, Feb. 1942. 
7. -is, %mas A., and PUTmr, Paul E.: Wind4"ael Lnvestigatim 
of an NACA 23012 A i r f o i l  w i t h  Two Sizes  of Balanced Split ?J'lap. 
NACA ACR, Nov. 1w. 
8. Lourg, John G. : W b P l k u m e l  Ibvestigatian of an NACA 23012 A i r f o i l  
with Several Arrmgmats of Slotted Flaps with Entended Lips. 
W A  TN 808, 1941. 
9. Harris, Thamas A.:  WindJTunnel Ihvestigatian of an R.A.C.A. 
23012 Airfoil with Two Arrangemepts of a WideChord Slotted 
Flap. NACA 9 5  715, 1939. 
10. Purser, Paul E., Fiachel, Jack, and Riebe, John M.: Wind-fcunnel 
Lnveetigation of an mACA 23012 Airfoil with a O.3-0il- 
Chord Double Slotted Flay. IWCA AFLR -0, 1943. 
i- 
11. Wenzinger, Carl J., and Harris, Thomas A . :  W I n d J J h n n e l  Lnvestigation 
of an M.A.C.A. 23021 A i r f o i l  with Various Arrangement8 of Slotted 
Flaps. RACA Rep. 677, 1939. 
7 
12. Duachik, Frank: W i n d - I p u n n e l  lbveatigatian of an B.A.C.A. 
23021 ~ r f o i l  with TWO Arrangements of a 4 ~ k ~ e r c e n m o r d  
Slotted Flap. mclcA T1B 728, 1939. 
13. Fischel, Jack, and Riebe, John M. : W i n d J h n n e l  Lwestigatian of 
an NACA 23021 AirfoKL with a 0 . 3 2 ” A i r f o i l ~ O r d  Double Slotted 
Flap. RACA ARR mm, 1w. 
14.-Holtzclaw, Ralph W., and Wei-, Y a l e :  Wind-1 Investfgation 
of the  EFfects of S lo t  .shape and FLap Location an the 
Characterietics of a Lar4rag Airfoil Equipped w i t h  a 0.25”hord 
Slotted Flap. IWCA MR ~4128, 1944. 
15. Abbott, Era H., and Fullmer, Felicien F., Jr. : W ” F u n m l  
Ihvestigation of XACA 63,41C20 A i r f o i l  w i t h  2>Percmt-Chord 
Slotted Flap. mAcA ACE 3I21, 1943. 
y 17. Lowry, John G., and m e ,  John W. : W i n d 4 u n m l  Investfgation of 
an NACA 23012 Airfoil with a 3O-Percent4hord Maxwell Slat 
and with ’Ikdltng4Edge Flap6 . NACA MR, June 16, 1941. 
18. Weick, Fred E., and Platt, Robert C.: Wind-Tmml Teste m Mdel 
Wing with Fowler Elap and Specially Developed  Leading-Edge 
Slot. mcA m 459, 1933. 
22. Blackburn Aircraft Reseamh Dept.: Wind Tunnel Tests on Moderately 
W g e  Chord Flap6 with Single and Multiple Slots. Rep. No. 6350, 
Brit ish A.R.C., Jan. 7, 1943. 
23. Fullmer, Felicien F., Jr. : Two4Olmenei& W5nd”nel 
Investigation of the IUCA 6%4l2 Airfoil Equipged with Two 
m e a  -of L e a d w g e  ?Jlap. NACA 1277, 1947. 
24. Fullmer, Felicien I?. , Jr . : Twdtmemiond. WindJl2unnel 
Ibveetigation of an XACA 64-OO9 Air fo i l  Equipped with Two 
Types of Leading4dge Flap. W A  Tm 1624, 1948. 
25. Underwood, Wiliam J., and Ruber, R o b e r t  J.: 'Jho4lmfmsianal 
WM4Bmnel lbvestigation at H i g h  R e y n o l d s  Number of Two 
Sgmmetrical CircularcArc Airfoil Sections with Ei&-LIft 
DevLces. XACA RM L6K22, 1947. 
26. Ruber, R o b e r t  J., and Cheeseman, Gail A. : Two-D,Jmansicmal Wind- 
Tunnel Investigaticm of a,64Pereent+t!hick Symmetrical Circulm- 
k c  ~ i r f o f i  Section with ~ead-~~ge and TraiUn@Edge IC€&- 
Uft Devicee Deflected in C c a n b i n a t i a n .  ETACA RM L W O ,  1949. 
27. Ruber, R o b e r t  J., and Gottlieb, Stanley M.: !W&DFmensianal Wind- 
Tunnel lhvestigatian at Hi& R e y n o l d s  Rnbers of an HACA 65.~006 
Airfoi l  with High-Lift Devices. HACA RM ~ 7 ~ 0 6 ,  1948. 
28. Thompsm, M. J.: A SlmpLe Method for Determining the AeroQnamic 
C e n t e r  of. an AirPoil. J&. Aero. %I., vol. 5,  no. 4, 
Feb . 1938, py . 138-140. 
. 
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(a) Extensible  slotted  f lap. (e)  Double s lot ted   f lap .  
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Figure 1.- General arrangement of various types of f lape and slate. 
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Figure 3.- Aerodynamic  characteristica ne&t~-maxhum section lift coefficient of several NACA airfoils 
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I 
I 


Survey of two-dimensional data on pitching-moment changes near maximum lift caused by deflection of high-lift devices

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