1、1 RESEARCH MEMORANDUM f- EFFECT OF AIRFOIL SECTION AND TIP TANKS ON THE AERODYNAMIC CHARACTERIsTIs AT HIGH SUBSONIC SPEEDS OF AN UNSWEPT WING OF ASPECT RATIO 5.16 AND TAPER RATIO 0.61 By E. Norman Silvers and Kenneth P. Spreemann Langley Aeronautical Laboratory Langley Air Force Base, Va. NATIONAL A
2、DVISORY COMMITTEE FOR AERONAUTICS WASHINGTON December 1, 1949 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-c* . CHARACTERISTICS AT HIGH SUBSONIC SEl3EIE OF AN UNSWEPT WING OF ASPECT RATIO 5.16 AXD TAPER RATIO 0.61 . By H . Nomm Silvers and Kenneth
3、 P. Spreemaan An investigation of the effect of two wing sections and a tip tank on the aerodynamic characteristics of a rigid unswept wing was made in the Langley high-speed 7- by 10-foot tunnel over a Mach number range extending frcm 0.60 to 0.90. Analysis of the results indicates that airfoil -se
4、ction had an appreciable effect on the aerodynamric-center location of the wing, that the trailing-edge angle of the airfoil sectionwas a prhcipal factor in controlling this effect at high subsonic Mach numbers, that the tip tank produced lese than 1.5-percent change in the aerodpmic-center location
5、 of the wfng regardlese of airfoil section, that the effective aspect ratio change poduced by the end-plate effect of the tip tank was appreciably larger when the gap between the tsnk and wing was sealed, and that the unstable pitching mament of the tank about a point locaked at 40 percent of the wi
6、ng-tip chord was neutralized by a hori- zontal tank fin which WBB 23 percent of the Wojected area of the tank. The behavior of auxiliary fuel tanks mounted at the tips of straight wings is well established (referenee 1) in the region of speeds where cmpressibility and aeroelastic effects are of seco
7、ndary importance- As the speeds of aircraft increase, hcswenr, cmpeseibility and aero- elasticity becaw of major importance even on a wing without a tip tank 80 that the necessity for obtaining informatian on the effect of tip- mounted tanks at high speeds is apparent. Provided by IHSNot for ResaleN
8、o reproduction or networking permitted without license from IHS-,-,-2 The results presented in this paper were obtained in the Langley high-speed 7- by 10-foot tunnel and include data obtained on two identical wing plan form having different airfoil sections, with and without a tip tank, over a Mach
9、 number range frcm 0.60 to 0.90. Also aham are the effects of two modifications to the trailing portion of me of the airfoil sections. Modifications to the basic pofile were accamplished by extending the wing trailing edge* The lift; and pitching-mment coef- ficients of the tank alme ln the presence
10、 of the rigid-unewept-wing model are included in the results presented. Pitching maments of the tank alone are presented about the 40-percent-tip-chord poFnt which is considered representative of the elastic-axis locatian of a flexible wing. The effect of hmizontal tank stabilizing fine on the prope
11、rtiee of the tank alme in pireeence ,of the wing are shown. The coefficients and symbols referred to in this paper are defined as follows: pitching-mament coefficient, referred to the 0.25 (original plan form) (Twice panel pitching moment/qs) drag coefficient (Twice panel . At M = 0.85 the aero- dyn
12、amic center of section B le about 16.5 percent ahead of the aero- dynamic center of section A or about 14 percent ahead of the quarter- chord point. A preliminsry examination of the pitching-ruoment characteristics of a number of airfoil sections made in reference 2 revealed that alrfoil sections wi
13、th large trailing-edge angles had aerodynamic-center locations considerably forward of those with mall trailing-edge weeD It is to be noted that section B, which haa an aerodynamic center forward of that of section A, has a trailing-edge angle approximately 2.5 times greater than section A. Provided
14、 by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM L9J, and the drag break Mach nmiber is slightly lower (figs. ll and 12) AB the lift coef - ficient is increased, the drag of section B increases more rapidly than does that of sectian A. (See figs. 6 an
15、d 7.) The poorer drag characterietics of the wing with section B 8re reflected directly in the lift-drag ratios. It is seen that section B (figs. XI. and 12). an (L/D) ap-pnatmately 10 percent lower than that of eection A The lift-curve dope of section B is lower than that of section A with the redu
16、ction generally increasing as the Mach nllpiber is increased until. (%/h, of section B is only about 65 percent of (%/h) of section A at the highest Mach rimer investigated (M = 0.90) (See figs. u and 12.) It is cautioned, however, that a quantitative spylication of these data to eimilar profiles at
17、 larger scale is attended bg same riak because of the smceptibility of the separation enmenan involved in Reynolds nmiber effects- Effeot of Modifications to Section B In an effort to move the aerodynamic center of section B as far aft as possible and still maintain a practical airfoil section, two
18、modifi- cations designed to decrease the trailing-edge angle were made to the aft part of the original hnees to sectioq B with modiffcatfan 1 (accentuated cusp trailing edge) is included in theae data (fig. 12(a) ) Reduction of the test Reynolds nmber results in a remd movement of the aero- dynamic
19、center of 2 yercent, but leading-edge roughnes has a Bmall effect on the aerodpdc-center location. Leading-edge roughness does, however, produce a large increase in drag coefficient. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 Effect of Tip Tas
20、k The maximum change in the aerodynamic-center location of sections A and B caused by adding a tip tank with t8nk gap open OT sealed is a farward movem.ent of about 1 5 percent mean aerodynsrmic chord below force break (figs. U(a) and 12(b) The drag characteristics of the wing-tank ccmibination with
21、 tank gap open and either airfoil section at zero lift coefficient as a function of Mach number tank on, gap op. * Figure I I. - Effect of M numk OR fk adynumk charucknsks of ,the wing with s&on A and a tip-mounfed auxiliary fuel hnk insfalbtfbn. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
