19MAR 1948

m!i%?&-tdATIONAii ADVISORY COMMITTEE FOR AERO

ORIGINALLY ISSUEDJune 1944ae

M3Uom’ndurilReport

DRAG~MIHIGIREYNOm m,mm

03?A MXM3mMEom m 23016 ImYImAL

cmYmtJcTIol’iWIrn sEcmoNSuBmmED

BY CHANCEVUJG3TAIRmu?I Cc&lJ?Arm

By AlbertE. vonDoenhof’fandRobertJ. Nuber

~ey MemorialAeronauticalIaboratoxyIangleyField,Va.

NACAWASHINGTON

N A C A LH3RARY

LWW3LEY MEMONAL AERONAUTICAL,LABORATORY

Langley Field, VCLNACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution ofadvance research results to an authorized group requiring them for the war effort. They were pre-viously held under a security status but are now unclassified. Some of these reports were not tech-nically edited. All have been reproduced without change in order to expedite general distribution.

—

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. .?31176 013(323914

- -----— ___NATIONAL ADVISCX?YCOMMITTEE FCR AERONAUTICS

—. ----. —.-

?$EMc&NDUM REPCXZT “

Bureau o: Aeronautica, Navy Depar&nent

IR4(3MEASUREMEN!R3AT

OF A 100-1~-CEORD

CONSTRUCTION WIN(3

BY CHANOEVOUGHT

13yAlbert E. von

. .

,

HIOH REW?OLIX NUMEERS

NACA 23016 PRACTICAL ~

SECTION StiMITTED

AIR& COMPANY .

Doenhoff And

INTRODUCTION

Calculation of the hiti-s~eed

Robert““J.Nuber

~erformanoe of someairplanes Involves the e8t1m4t~on 02 airfoil tiag coef-ficients at ?leynoldsnumbers of the order of 65to 75 million. Very little data a airfoil drag ooeffl-olents at such high Reynolds numbere are avaiIabIe. Atthe request of the Bureau of Aehonautlcs, Navy Departnwmt,therefore, drag measurements were made In the LangleyMemorial Aeronautical Laboratory two-dlmenstonal low-turbulence pressure tunnel Of an available 10(’)-inch-ohordmodel of the NACA 23016 wing section. The model w~.soOn-atructed by the Chance Vought Aircraft Company accordingto practioal construot~on methods, In me p~sen$ .~sries of tests, seotlon drcn ooeffioients rmre

The

over a-range o? Refiolds numbers from approxl-to 68 million at lift coefficients from about.0.275 with three types of eurface copdltions.

IEWRIPTION OF MOiEL”AND .TLST”METHOti

100-inch-oh=d NACA a3016 winK aeclilonused for“thesetests had a single spar iooated.~t the 30-peroent-ehord station. Both the upper and lower stifaoes wereunfair at this point. ?n addition, a flat spot located

i. A

.— . .—— ..

2 .. .

at approximately the OS.095c station onand extending halfway across the mtiel

-.

the lower surfacespan was detected

by rocking a-straight edge over-the forw--d portion ofthe slrfoil in a chordwise direction. The skin forwardof the spar was approximately 0.050 inch thick “andwasriveted to both chordwise and spanwise stiffeners. Athinner skin (approxlmatel~ 0.015-inch thick) aft of thespar was riveted to chordwise stiffeners spaced 9 inchesapart.

?he tests were made with the model surfaces In threeconditl~ns:

(1) AS received.- As received, the model was paintedwith zinc chromate primer.““A few rivets behind-the sparhad been glazed. Three minor scratches located on theupper surface near the leading edge, which were apparentlythe result of handling and shipping, were filled andsanded smooth.

“(2) Painted.- All local surface defects forward of’the .spsr,~s rivets, were faired and the surfaces”were spreyed with gray primer surfacer which was sandedsmooth. The surfaces behind the spar were also paintedand sanded, but no attempt was made to correct local

. surface defects.in this region.

- (3) Camoufla ed.-~.y ~~~~~a~~~ ~~.nfi%; ~? ~camouflage paint

sprayed over the gray-primer surfacer (condition 2). Noparticular eff’ortwas made to spray the’.camouflagepainton smoothly because, for this condition, It was desiredto simulate the spraying abilities of an,tnexperienced “person. Door jalnts were simulated by shellaoki~~ alength of string 0.012-irtchin diameter at the 0.25c sta-tion across the span on both the upper and lower surfaces.%otographs of the model showi

Ythe simulated door joints

are given in figure l(a) and (b . A rear bottom view ofthe model Is presented In fig@e l(c)-to”shchithe rivetspacing and surface irregularities.

Lift and-drag coefficients were obtained by themethods described in reference 1~ The data have beencorrected for tunnel-wall constriction by the followingformulas: . .

\L 7

. ●

3

.,i- .- ----- .

“..4.

where the -primedquantities relmesent the values of theooeffiolents measured In the’”t@nel.

\

R3SULTS AND IULCUSSION

Curves of saotion drag coeflio~ent plotted againstReynolds number for various surfsze cotiitIons and llftcoefficients are given in figure i . A comparison of theresults presented In figure 2(c) w :th the skin frlotlonof smooth flat plates is presented In figure 3.

It is seen from figure 2 that ‘-h”.variation of drag‘ooefficlentwith lift coefficient, ~X.ttculsrly at himReynolds numbere, wae relatively small. Above a Reynoldsnuriberof 25 million, the changes in s-.mfacecondition ofthe model had m,oreeffect on the dra{*coefficient thanchanges In the Reynolds number. As would be expeoted,the lowest drag coefficients were obtialnodwith theemoothest surfaoes (condition 2).

The variation of the profile dra{”of’this airfoilwith ~.eynoldsnuiiberwas similar to tkat of the turbulentskin frictton of smooth flat plates up to ~ Reynoldsnumber of approximately 15 million. A)ove this Reynoldsnumber, the scale effect on drag was a~=ll. Theseresults apyear to be slmllar to those .~or rough pipesgiven on page 46 of reference 2, wher~ the’skin friction .of pipes with relatively small surface roughness at firstfollows the same curve as for smooth pipes. At scauehigher Reynolds number, depending upon the grain size ofthe roughness, the skin friction approaches a constantvalue and shows little further change even up to extremelyhigh Reynolds u-d.,;~ers.As in the case of the rough pipes,the value of the drag coefficient, for the present tests, .

-- at high Reynolds numbers was prmlly a furmtion of themodel surfaoe condition. .

Although extrapolation formulas based on the skinfrtction dra of smooth flat lates maybe reliable for

9 fairfoils hav ng aerodynamical y smooth surfaces, the

L“——

— —

4 .

4

data presented herein indfeate that, at least for modelshaving surface conditions sidlar to those of the presenttests; such formulasthe drag coefficient

would tend to give too low values ofat high Reynolds ntibers.

CONCLUSIONS

As a result of tests of an NACA 23016 practicalconstruction section over a range of Reynolds numbersfrom approximat~l~ h to 68 million, the following con-clusions may be drawn:

1. Above a Reynolds number of about 25 million, theohan~es in surface condition of the model had more effecton the dra~ coefficient than chan~es in the Reynoldsnumber.

2 ● Zxtrayolation formulas based on the turbulentskin friction di*~~ of smooth flat pl~tes tend to givetoo low values of’the drag coefficient at hi~h Reynoldsnumbers when applied to airfoils having suri’acescompa-rable to those of the model investigated in the presenttests.

Langley Memorial Aeronautical LaboratoryNational Advisory Committee for Aeronautics

Langle:-Fleld, Vs., June 30, 19~

. .

!!

REFERENCES

1. Jacobs, Eastman N., Abbott, Ira H., and-”Davidson,Milton: Preliminary Low-Drag-Airfoil’.andFlapData from Tests at Large Reynolds Numb’ersand LowTurbulence, and Supplement. NACA ACR, .Mtirch1942.

2. Prandtl.,L.: The Mechanics of Viscous Flul?k.Vol. 111, div. G, sec. 25 of Aerodynamic TheorysW. I’.Durand, cd., Julius Springer (Berlin),1935, ‘p. 46.

-..:—

(a) Fronttopviewshowingsimulateddoorjoint.

Figurel.- PracticalconstructionwingmodelofNACA 23316 sectionsubmittedbyChanceVoughtAircraft,camouflagepainted.

(b) Frontbottomviewshowingsimulateddoorjoint.

Figure 1.- Continued.

(c) Rear bottom view showing rivet spacing and surface irregularities.

Figure 1.- Concluded.

.

V*

c

.

.

.

Iiiiiiiiii iiiRqnolda number, R

Kmml #mlwvCOWMEEFIMAUMUIES

.012

.008

.04

0

Reynolds numhr, R

pi~. z .. nag SOah ●ffoot of a 100-lnc~;:~d MM 23016Pmctlcal construction wing motion sutmittod by Chance Vought Aircraft., ‘KIT450, 432, and ~~.

I

.014(c) c1 = 0.075 approx.

.Ooe-%k +— -

l— -J = z’ 3 == = =

>

‘~-’ ~x ‘>

. 1c— –x— — . . ~+

x x% –+

‘+ I‘+

x-0,+

c1 Condition of Model

.OOL o 0.079 1- As recei~ed+ 0.077 2- Palntad with gray primer

surfacerx 0.074 3- Camouflage painted with

simulated door jointsGo 4 8 12 16 20 24 28 32 36 40 ~ 48 52 56 60 & 68X106

Reynolds number, R

NATICNN AOWWRY

COMMITTEE FOR #H7WiUTCS

.012(d) c1 = 0.45 approx.

x..008— — +- q <— x—

+— q ;;x

+ g--:

n > “ ux- — ~ . q —

+- —+ + + + i

% ‘-- “-”Coi=ltlon of- Mdel

.004? ;:$8 ;~%&%’~~hgrayprimer

surfacerx 0.1L2 3- Camouflage painted with

o simulated door jolnta

o h 8 12 16 20 24 28 32 56 40 & 48” 52 56 60 64 68xlo6

Reynolds number, R

~Rure 2.- Continued.

.,

I

I

I

.o16r

2(0)c1= 0.2758PPIVX.

.4s .012G+: x\Q*

.008‘ h _’ ( ..) x— -x— — 3‘ A F x xuz +

? [ ‘1 ?Mmdition of Modol:

●004c

o 0.269 1- AIIreoei.vod; + 00275 2- Painted with gray prh.r

2* surfacero x 0.276 ~-Camouflage patitedwiths al.mulated door jo,lnts

o- A . . L

Reynolds number, R

?&me 2.. Concluded.NATIONALAOMSORY

COMMInEE FORAEROMUTiCS

1

1 2 3 45 10 20 To 40 to 100

Reyno15s Number, R x 10-6

Figure ~.- Compa~ison of the drag coefficient of the NACA z3016airfoil section with the skin friction of smooth flat plates.

A/UK. TlTlfc nrag moaaurcson^p at high Boynoldo nuaboro of a 100- Inch- chord HACA 23016 practical canotruotlon wing aoctlon eubnittod by Cfcanco Yought Aircraft Caaipany

ORIGINATING AGENCY: national Advioory Ccamlttoe for Aeronautics, tiashlngtan, D. C. TRANSLATION:

VOB Doanhoff, A. E. Dubor, B. J.

AUTKCOtS)

DIVISION: Aorodyoanlco (2} SECTION: Hlngs and Alrfolio (6)

I CROSS REFERENCES: Drag, Aorodynanlo - Skin fr lotion (31290),' Alrf olio - Drag (08200)

LANGUAGE FEATURES phot 03, grapho

COUNTRY U.S. r >BG'N.CLASS] U. SJCLASS.

Unelaso. DATE PAGES

Jnn'l* 13

flQOTQACT Toots WCQPO coadmcted on a 0ACA 23016 wing ooction over a rango of Boynoldo mmboro :

b to 68 nllllan for too purpoao of obtaining drag data. Boonlts ohow that abovo a Boy- nolds number of 25 Dllllon, tho chongoo In surfaco condition bad EOTO offoct on drag ca ficlent tban ohangos in Boynoldo nanbor. Extrapolation foraal&o booed an the turbulent skin friction drag of ocooth flat plates tond to glvo tpo lotr valooo of tho drag cooffl clont at high Boynoldo robbers vhon applied to alrfoilo slollar to tho codol tested.

nOTE; Boonooto for coploo of thlo roport neat bo eddroooed to: H.A.C.A., Eaohlngtan, D. C.

T-2, KQ„ AIR MATHSa COMMAND 7&T1 ECHNICAl UNDSS WRIGHT Fiao. OHIO. USAAf (at