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Distribution authorized to DoD only;Administrative/Operational Use; 20 FEB 1947.Other requests shall be referred to NationalAeronautics and Space Administration,Washington, DC. Pre-dates formal DoDdistribution statements. Treat as DoD only.

NACA research abstracts no. 70 dtd 21 Sep 1954;NASA TR Server website

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ItfMSEESENTIAL^^SSi Fi£D RM No. L6I11

KACA

RESEARCH MEMORANDUM

DRAG MEASUREMENTS OF A 34° SWEPT-FORWARD AND SWEPT-BACK

NACA 65-009 AIRFOIL OF ASPECT RATIO 2.7 AS

DETERMINED BY FLIGHT TESTS AT SUPERSONIC SPEEDS

By

Sidney R. Alexander

Langley Memorial Aeronautical Laboratory Langley Field, Va.

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NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS :->T ^-M

WASHINGTON : ^ ^ / v,» February 20, 1947 '-«••-"•-••" ' '"

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TRAG KEASUREJ.'ENTS OF A 3hP SV-EPT-FORSARD AKD SYTBPT-BACK

TACA 65-009 AIRFOIL C-T ASFECT RATIO 2-7 AS

DSTERKINED BY FLIGHT T?STS AT SUPERSONIC SPEEDS

By Sidney R. Alexander

SlEEiSY

"This report presents results cf flight tests conducted at the NAOA Filotless Aircraft Test Station at Wallops Island, 7a., • to determine the zero-lift drag of as KACA 65-OO9 airfoil of aspect ratio 2.7 sveptforward ?h°* The data were obtained by tracking rocket-propellsd winged bodies novin£ at supersonic speeds. A corxarison is made between the results of similar tests of an unswept and a 3^° swepfc-back arrangement of a previous report, JIR 5?o. L6EI7,and of this report. The test results show that for the comparable Mach number range investigated (M = 0.'? - 1«?0) both the Jü0 sv-'eot-forward and swept-back airfoils produced lower values of zero-lift drag than the tcsv-iot airfoil. At .Yach numbers between 1.0 and 1»3* the drag of the f^ept-back wing war f-bout 50 percent and that of the s.vept-for«ard using about 65 percent of the drag of the unswept winp.

IWTfiODUCTIOM

It is well established that the aerodynamic characteristics of wings in the proximity of sonic velocity could be considerably improved by the use cf a Ian forms having suitable sweep -ingle. The effects of sveenbask h^tve been experimentally verified by various means such as the investigation of reference 1 in which the results of super sonic flight t* sts of swept-b&ck airfoils have been presented. Recently, however, from practical oonaiderations such as improved Literal stability and stalling characteristics, more than usual interest has been exhibited regarding the use of swert-for*ard wings for high-soeed flight. To obtain information relative to the drag of sv.ept-forward wings at supersonic speeds, tests are being conducted at the ?;ACA Pilotless Aircr.ft Test Station at Y«allops Island, Va., of rocket-pror=Iled bodies carrying wings of

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various sweep-forward angles and aspect ratiost This report presents •bhi.-! results of drag teste of a. J>k° swept-forwerd NACA 65-009 air- foil of aspect rsbio 2.7« This aspect ratio is fcas^d on the total wing sn^n and area including that portion enclosed by the- tody. For comparison, the results of the »inswe.pt oad 3h° swept-back air- foils of equal asoect ratio, rreserted in reference 1, are included.

PODY AND TESTS

Body

A rhotograoh of the- test body equirwed with the 5J4.0 swe-pt- forward airfoil is presented in figure 1 and the gerers-1 tody arrangement is shown in figure 2. The airfoil was mounted on the fueelago at asro angle of '..ttriok with the nddsemisf&n yu&rter- chord noint at the same longitudinal station as the dcsijgi center of gravity. The "ACA 6^-00'} airfoil (chord norx.v*l to lsuding edge) hid ntither taper, twist, nor dihrdral. The unswept and "}l\P swept- baek configurations of reference 1, presented in figure 3, differed from the. 3h° swept-forward arrangement only in wing nlun form and location. T*;o test bodies of each configuration «ere i'ired under similar atmospheric conditions, and the results averaged in the evaluation of the data.

All the test bodies were propelled by J.25-inch diameter y?.rk 7 aircraft rocket motors fncioeed within the bodies. At a rrei-rnition t«irirvera'r-uro of 69 ° F» the rocket motor provided about 2200 pounds of thrust for approximately 0.87 second.

Tests

The ?/-i° sv,er>t-forward test body, as ws;ll ar the bodies of reference 1, were launched :?.t; an elevation asgle of 75° to the horizontal» Because of the high elevation a^glo and the short burning duration of the rocket motor, the trajectory of tvfce lodi.es during their suwrsonin coasting flight, -after the rrore llont w?.s expended, was approximately -x straight line. The flight velocity was measured during thi s coasting period by means of a C. '.V. Doopler radar set (A>I/TPS-5) located at the point of launching.

RESULTS AMD DISCUSSION

The variation of velocity with time for one of the 3U° svs-ept-forwird models, ar- measured with tht radar unit, it presented

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in figure !>.. The negligible .amount of scatter indicates consistent data. The portion of the Telocity curve during which the body «ras coasting (after the end of burning') was graphically differentiated to obtain the deceleration. The product cf the deceleration and the known body mass was equsted to the sum of the drag and the known weicht of the body. The values of the drag thus obtained are presented in figure 5 as a function of the flight, velocity for both models of the 3 if0 swoot- for ward arrangement, A single resultant drag curve was faired through these points, iilthourh the scatter of the velocity- tine cur^e has been greatly magnified by its differentiation, the curve is satisfactorily dots-rained, the average scatter of tho experimental points from the faired curve being about ±3 percent.

Prom the drag curve of figure 5» "the total drag coefficient of thp body with the 3^+'" swept-* crward airfoil has been computed and is nres6"tsd in figure 6(a^ 'slotted against Mach number. The ^ing drf;..; coefficient, derived fcy graphically t2ki:.i the numerical difference between the winged body and one identical to it, but without wings, is presented in figure 6(b'!. For comparison, the drag-coefficient curves for th^ test bodies with the unswept and 3i!4ü swept-back airfoils of refcrencj 1 are included. The values cf wing drag determined by the above method include v/ing-f use lags interference effects. The drag coefficients were based on the constant esncsvd wii'-i: olan-form area of 200 square inches. Examinat-ior of th;- figure rtveals that for the Kaih number range investigated, thK.- drae of either swept wing was less than that of the unswept vfiug. This effect was more oronouaccä for the case of the swect- taok v.-iag. The drag of the sw;ot-back wing was about 50 percent and thi.t of the swert-forwitrd v;inr .^bout 65 r-trcent of the drag of the unsircvfc wins. Aside from any differences in tip drag, part of the increase in the drag of the sv.eot-foriv-.rd wing over that of fcht? sweot-b;-ck one can be attributed to differences in flov.- in the wing-fuselage juncture; this floft telr.g largely a function of the sweep angle and direction.

The results of supersonic flight tests to determine the drag of a 3I4.0 sweet-forward ?IACA 65-QO9 airfoil of aso'-ct ratio 2*7 mounted on a rocket-orooelled tody have been "resetted herein. The drag coefficients of an unsw..--t and a 3J40 swept-baok airfoil of equal aspect ratio obtained in an idetirical fashion hive also been included as a basis for comparison. Eetween 1'a.ah numbers of 1.0 and 1.3, the drag of the ewspt-back wing was about 50 percent and

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that of the swept-forward wing about 65 percent of the drag of the unswept wing.

Langley Memorial Aeronautical Laboratory National Advisory Committee for Aeronautics

Langley Field, Va.

REFERENCE

1. Alexandert Sidney R., and Katz, Ellis: Drag Characteristics of Rectangular and Swept-Back NACA 65-OO9 Airfoils Having Aspect Ratios of 1.5 and 2.7 as Determined lay Flight Tests at Supersonic Speeds. NACA RM No. L0JI6, 19k6.

NACA RM No. L6I11 Fig. 1

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Figure 1.- The test body with 34° swept-forward wing of aspect ratio 2.7.

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Figure 3(b).- The test body with 34° swept-back wing of aspect ratio 2.7 (reference 1).

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iiDr.JRI'I)Ic:JD(ISF>::l41) ~Il. Alexander, S. R.- DIVISION, Aerodynamics (2)

SECTION, 1Iil189 and Airfoils (6)

UTHOR SI

CROSS REFERENCES, Airfoils - Drag (08200}; Airfoils, Svept-back - Drag (08280)

AMEn. TITle> Drag lIIG8.9urements of a 3 swpt-forvard and svept-back IIACA aspect ratio 2.7 as determinsd bl flisht tests at supereonic

FORG·N. TmE,

ORIGINATING AGENCY, Natioilal. Advisor,. Camn1tte8 for Aeronautics, Baahlngton, D. C. TRANSLATION, •

COUNTRY U. S.cLASS. U.S. Contd'l Feb '47

AQ»'U'ClA(1T The drag of a 340 swept-forvard and svept-back airfoil was measured. The data we ob­

tained b,. tracking rocket-propelled winged bodies moving at supersonic speeds. CoapariSOD is made bet .... en results of s1m11ar tests of previous reports and of this report. Test re­sults show that both tbe 340 swept-forward and swept-back airfoils produced lover values of zero-11ft drag than the unevept airfoils. At Mach numbers 1.0-1.3, -drag of svept-back wing Vas about 5~ and that of svept-forvard ving about 6~ of drag of unewept wing.

NOTE: Requests for copies of this report must be addrssssd to: N.A.C.A., washington, D. C.

T·2, HO., AIR MATERIEL COMMAND L.S;""'jj' eC:/fffic;.\LlltiPEX ~~

WRIGHT FIELD, OHIO, USAAF aJ..O.21 f:\AQ Q l!::l

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UNCLAS$lFJEI) per . authority of N,ACk Research Abstr~ts No •. 70 . -. dated 21 $ePiember.1954. ·(l4~O~t54)':.· '. . -' ,.

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