1、NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS ORIGINALLY ISSUED October 1944 ae Advance Restricted Report IhJO5 m- -GATION OF rn ACA 23021 PIFOIL WITH A O.-AIRFOIL-CHORD DOUBLE SIXFIZD FIJQ By Jack Fiechel and John M. Riebe Langley Manorial Aeronautical Laboratory Langley Field, Va. WASHINGTON NACA WA
2、RTIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance 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
3、. All have been reproduced without change in order to expedite general distribution. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-t *, L) NACA RRR NO* L4J05 - NATIONAL ADVISORY COMMITTEE FOR AEROIJAUTICS AEVANCE RESTRICTED REPORT :*JIXD-TTUNAEL IN
4、VZETIGATION OF AN HACA 23021 AIRFOIL *JITH A 0.32-AIRFOIL-CHORD DOUBLE SLOTTED FLAP By Jack Fischel and John M. Riebe An investigation was made in the LML 7- by 10-foot wind tunnel of an ITACA 23021 airfoil with 8 double slotted flap having a chord 32 percent of the airfoil chord (0.32) to determine
5、 the aerodgiianic section charac- teristics with the flaps deflected at various positions. The egfects of moving the fore flap and rear flap as a unit and of deflecting or rernoving the lower lap of the slot wem also determined. Three positions were selected for the fore.flap and at each yosition th
6、e maximuii lift of the airfoil was obtafned with the rear flap at the naximum deflectLon used at that .fore-flap position. The section lift of the airfoil increased as the, Pore flap was extended and maximum lift was obtained with the fore flap deflected 30 in the aost extended posit ion. a rilaxI!i
7、m section lift coefficient of 3.31, which was higher than the value obtained with either a 0.2566 or a 0.li-O single-slotted-flap arran-ement and 0.25 less double-slotted-flap arrancement on the same airfoil. The values of the profile-drag coefficient obtained with the 0.32 double slotted flap were
8、larger than those for the 0.2566 or O.I;OC single slottea flaps for section lift coefficients between 1.0 and approximately 2.7. At all values of the section lift coefficient above 1.0, the 0.40 double slotted flap had a lower profile drag than the 0.32 double slotted flap. section lift Coefficient
9、produced by various flap deflections, the 0.32 double slotted flap gave negative than those of other slotted flaps 011 the same airfoil. The 0.32 double slotted flap gave a2poximately the same maximum section lift coefficient as, but higher profile- This arrangeinent provided than the value obtained
10、 with a O.L+OC r At various values of the maximum h section pit ching-moment coefficients that were higher d Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACA ARR No. aJ05 APPARATJS AED TESTE Models An NACA 23021 airfoil wfth a 3-foot chord and
11、a 7-foot span was the basic model xeed in these tests. c The ordinates for the NXA 25021 airfoil section are given in table I. nated mehogany and tempered wall board and is the same The airfofl waz constructed of lami- L _ _ A- drag coefficlents over tho entire lift range than, a similar arrar-gemec
12、t of a 0.3Cjc dcuble slotted flap on an NACA 23612 airfoil. I TKTHODUCTIOX The National Adv! sory Covmi.ttea for Aeronautics has undertaken en sxtenrjim investigation of various high- lift devices in order to rurrdsh inf3m.ation a9plicab2-e to the aerodynamic design of wirq-flap coinhinations that w
13、ill improve the zafetq and periormarxe of airplanes. For use in take-off anc?. initial climb, a high-lift device capable of producing high lift with low drag is desirable. For xse in landing?, k.owsve:ll, htgh lift with variable drag is belleved desi7able. Other desiraSle character- istic? are: no i
14、ncresse in Craz wit3 the flap neutral, small change in pitchhg norwit; with flap deflect20Li, low forces required to ogerats the flap, and frc:sdom from possible hazard due to icing. The results of various InvestfgatLons on the NACA 25021 z9rfoil are preserited in references 1, 2, and 3. ResElts for
15、 the NACA 22021 airfoil. with a single slotted flap havirg a chord 25.66 percefit of the airfoil chord (0.2566) are given in reference 1; results for the same airfoil with a 0.43 single slotted flap and with a 0.40 double slotted flap are given in references 2 and 3, respectively. The present invest
16、igation, in which tests were made of a 0.32 double slotted flap 0x1 the NACA 22021 airfoil (ffg. l), 5s a continuation of the investigation reported in reference 4 of a 0.50 double slotted flap on an WkCA 23012 airfoil. W Provided by IHSNot for ResaleNo reproduction or networking permitted without l
17、icense from IHS-,-,-NACA AFR RO. 405 3 i! I. airfoil previously used for the investigations reported in references 1, 2, and 3. The trailing-edge section of the model ahead of the flaps was equipped with lips of steel plate rolled to the afrfol.1 contour and extending back to the rear flap in order
18、to provide the basic air- foil CoiltoW when the flaps were retracted (fig. 1). The double slotted flap consisted of a fore flap and a rear flap. The fore flap (0,1467c),tested was the same one designated fore flap B in the investigation reported in reference 4 an6 had an upper surface and trailing-e
19、dge of dural and a lower surface of laminated wood. The fore-flap profile is shown in figure 1 and its ordinates are given in table I. The rear flap (0.2566) tested was the one used in the investigations reported in references 1 and 3. Its proflle is also shown in figure 1 and the ordinates are give
20、n in table I. Both the fore flap and the rear flap were attached to the main part of the airfoil by special fittings that permitted them to be moved and deflected independently. Each flap also pivoted about its own nose point at any position; increments of 5 deflection were provided for the fore fla
21、p and increments of 10 deflection for the rear flap. The nose point of either flap is defined as the point of tangency of the leading-edge Erc and a line drawn perpendicular to the flap chord. The deflection of eLthor Flar, was measured between its respective chord and the chord-of the main airfoil.
22、 The model vias made to a tolerance of JcO.015 inch. Tests The model was mounted vertically in the closed test section of the LMAL 7- by lO-foot tunnel and completely spanned the jet except for mall clearances at each end. (See references 5 and 6.) The main airfoil was rigidly attached to the balanc
23、e frame by torque tubes that extended through the upper and lower boundaries of the tunnel. The angle of attack of the model was set from outside the tunnel by rotating the torque tubes with a calibrated electric drive. This type of installation closely approximates two-dimensional flow and the sect
24、ion characteristics of the model being tested can therefore be determined. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 NACA ARR No.bers Re (reference 7) were * I / approximately 3.6 x 1.0 a J,+Z x IO, respectively. In each case, Re with the fla
25、ps retracted acd on a Cuw-bulence fsctor of 1.6 for the LMAL 7- by 3.0-Toot wind tunnel. 1s baeed. 03 the ehord of the airfoil No tests were made of the plain airfoil nor of the model with the flaps coa.ete3$ Pekaocted because the characteristics of the plain airfoil had previously been investigated
26、 and reported in refcrcnce 1. The optimum flap positions for the various flap deflections were considered, for purposes of making the best selection, to be the positions at which either maxinwn lift, minimum drag, OT minimum pitching moment was ostained, although, as previously indicated, a variable
27、 drag is desired for landing conditions. Three positions of the fore flap were selected in determinina various extended positions of the flaps or a possibleupath for the extension of the flaps. least extended fore-flap positfon, having a 5O deflection (position l), and the chordwise location of the
28、inter- mediate position (position 2) were chosen arbitrarily. The location perpendicular to the chord and the 20 deflection for position 2 were optimum as determined from a maximum-lift survey with the rear flap deflected 500 and 600. Because of the large nu.nber of tests involved in deterxining the
29、 optirnun-lift position of the double slotted flap, a preliminary survey was msde to determine the optimum position and deflection of the most extended posLtio2 (position 3) of the fore flap with the rear flap deflected 600 and 70 at various positions. Tests were thereafter made with the fore flap a
30、t each of the three selected positions in order to determine the maximum lift ?he Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IJACA ARR no. L4J05 5 c 4 P and the optimum position of the rear flap at several deflections. Data were obtained for rea
31、r-flap deflections. of loob 20, 30, and 40 at gosition 1- 30, bo0, 50, and 60 at position 2; and 4-0 , 50, 606, and TO0 at position 3. 1nasmuch.as it appeared likely that only small rear-flap deflections would be used with the least exteaded fore-flap position and that only large rear-flap deflectio
32、ns would be used with the most extended fore- flap position, the tests were confined to these configu- rations. In order to determine the effect on the aero- dynamic characteristics, tests were also made with the lower lip of the slot in its normal position on the contour, deflected l9O within the a
33、irfoil contour (at fore-flap position 2), and completely removed (at fore- flap position 3). No scale-effect tests were niade because the results of earlier tests of the NACA 23021 airfoil with a slotted flap (reference 1) are considered anplicable to the results of the present investigation. attack
34、 for maximum lift was covered in 2O increments over most of the range for each test; however, when the stall condition was approached the increinent was reduced to lo. Very little data were obtained for angles of attack above the stall because of the unsteady condition of the model. Lift, drag, and
35、pitching rnonent were measured at each angle of attack. An angle-of-attack range from -60 to the angle of RESULTS AND DISCUSSION Coefficients and SpnboLs All the test results are given in standard section nondimensional coefficient form corrected for tunnel-wall effect and turbulence as explained in
36、 reference 6. Ct * section lift coefficient (t/qc) section profile-drag coefficient (do/qc) CdO * section pitching-moment coefficient about aerodynamic center of plain airfoil Cm(a.c. lo Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-XACA ARR NO, 40
37、5 6 sect ion pitching-nomont coefficient C“(a-c* 1.3 at maxi;nim section lift coefficient CZ,X Omin Cd where Z d0 m(amc. )o 9 C V P and Re zt =0 6f2 . x1 maximum section lift coefficient minimum section profile-drag coefficient sect ion lift section profile dmg sect ion gitchlng momenk about aerodgn
38、anic center of plain airfoil (fig. 2) dynamic pressure (2+pV2 chord of basic airfoil wPth flap fully retracted velocity, feet per eecori6 mass density of air effective Reynolds xumber distance from aerodgnariiic center of airfoil to center of pressure of tail, expressed in abfoil chords angle of att
39、ack for infinite aspect ratio fore-flap deflection, measured between fore- flap chord and airfoil chord rear-flap deflection, measwed between rear- flap chord and airfoil chord distance from airfoil upper-surface lip to fore-flap-nos= point, measured parallel to airfoil chord and positive when fore-
40、flap- nose point is chead of lip r* L. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-* 7 PACA ARR No. 4J05 S distance from airfoil upper-surface lip to fore-flap-nose point, measured perpen- dicular to airfoil chord and positive when fore-flap-nose
41、 point is below lip 71 x2 distance from fore-flap trailing edge to rear-flap-nose point, measured parallel to airfoil chord and positive when rear- flap-nose point is ahead of fore-flap trailing edge distance from fore-flap trailing edge to rear-f lap-nose point, measured perpen- dicular to airfoil
42、chord and positive when rear-flap-nose point is below fore- flap trailing edge Pr e c i s ion The accuracy of the various measurements in the tests is believed to be within the following limits: a, degrees f0.1 Zmax *0.03 . .0.003 m(a.c. lo fo.0003 Cdonlin . *0.0006 Cd“(cZ = 1.0) e . . *O.O02 = 2.5)
43、 Cd 64 aqd 6 degrees . f0.2 f2 Flap position . f0.001 No corrections were determined (or applied) for the effect of the airfoil or flap fittfrrgs on the section aerodyiamic characteristics because of the large number of tests required. It is believed, however, that their effect ?.s small and that th
44、z relative values of the results would not be appreciably affected. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a Fore -flap position Flain Atrfqil Position of rear-flap nose Ahead of lip 1 Below lip (per cent (percent airfoil chord) 1 airfoil ch
45、ord) KACA ARR No. d+JO5 1 2 3 The complete aerodynemic section characteristics of the plain EACA 23021 airfoil (froin rleference 1) are presented in figure 2. been discussed in reference 1, no further comment is be iieved ne ce s sar y . Sime these data have already 6 2.71 2 3.06 3 3.31 1 0 2 Determ
46、ination of 0p.tbu-m Flap Configurations Maximum lift.- The results of the maximum-lift inves- tigation with the for5.e flap at each of the three selectod positions and with the rear flap deflected and located at points over a considerable area wlth respect to the fore flap are presented In figures 3
47、 to 5. The results are presented as contours of lift cmfflcient for various positions of the rear-f3ap-nose polnt at various rear- flap deflections. TlrJe rs$u3Cva show that at each fore- flap position, the contows 61j.d not close at the srnaller rear-flap deflections inmstipited, At positions 1 and
48、 2, it is indicated that the open conccurs xould clos3 at positions of the rear-flap nose that would be impracticable because of the large gap betwen the two flaps. At each of the three fore-flap positions, as the flap deflection increesed, the position of the rear flap for maxhm section lift coefficient became more critical - that is, a given movement of the rear-flap-nose point caiised a greater change in the value of . Since the position of the rear-flap nose for c tends to move forward and upxard as its deflection increases, tbe gap between the two flaps is obtained at each fore-
