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Aviation History
1921
1921 - 0311.PDF
MAY 5, 1921 SOME EXPERIMENTS ON THICK WINGS WITH FLAPS* By C. D. HANSCOM, Chief Engineer of the Glenn L. Martin Co. THE subject of thick wings has been taking on a constantlyincreasing importance in aeronautical discussions for several years. Since the War, with the urgent necessity for instantproduction removed, aeronautical engineers have been turning to practical experiments. It should, therefore,aid in general aeronautic development if all information on * Paper read before the Society of Automotive Engineers. "?4 5 10 20 JO 50 Dc, Lc AND L/D CHARACTERISTIC CURVES AND SECTION ORDINATES FOR THE GLENN MARTIN 3 WING SECTION 0.004O 0.0058 MOM (MOW Q05SO 0.0028 0.0024 0.00!? j 0.00JO 20 j 0.9016 18 O0OI6 16 0.0014 14 O.OtJlZ QI2 00010"1 10 00008 8 0.0006 6 0.0004 4 0-OOOi i 0.0000 I 7 L X 0 2 4 6 8 10 12 Anglo of Incidence,dog \ o.ooio 0.00O9 0.0005 0.0001 0.0006 00005 o° 0.00O4 O.OOOJ 0.000Z 0-0001 the subject is made available for common use. The GlennL. Martin Company has recently had tests made in the wind tunnel of the Massachusetts Institute of Technology in theendeavour to obtain more data on the action of wings with flaps. Both front and rear flaps were employed, and theresults showed several interesting features. \Vhen it was decided to have the experiments made, no sections were athand which possessed all of the qualifications needed. It was especially desirable that the movement of the flaps shouldproduce minimum discontinuities of surface. This require- ment at once limited the choice of sections. Ultimately fourbase sections were adopted and the new wings developed from them. Four Master Sections The first, and most logical, choice was the U.S.A. 27.The wing developed from this section eventually proved the best of those tried. The second base section was awing of my own, the Hi, the data for which has never heretofore been published. A third base section, which isnow being shown for the first time, by permission of its de- signer, G. M. Denkinger, was the D.I. The fourth mastersection was a composite curve which resembled no wing in particular. From these master curves, six new wings were designed.The U.S.A. 27 was thickened appreciably, and minor modifica- tions were made in its form. The new section was calledthe No. 2. The D.i was uniformly increased in camber, by a percentage ratio, producing the Glenn Martin No. 5.The H.i was modified in three ways. The rear upper surface was raised in all cases to allow more room for the flap. Thisinjured the qualities of the wing to a considerable degree. One wing, designated as No. 1, was then made having a sharp• trailing edge ; another, No. 6, with a blunt trailing edge ; and a third, No. 4, with a blunt trailing edge and a practicallyflat under camber. The fourth master section was modified- only slightly, having been designed especially for the purpose.This latter was called No. 3. The six models and the sockets were made at the Massa-chusetts Institute of Technology by its employes. The ordinates given in the different illustrations were scaled 14 16 18 20O-OOOO 18 JO 1,/D CHARACTERISTIC CURVES FOR TRB QLCITN MARTIN 6 WING SICTION 0 ?5 5 10 \ —• ——- 20 SO 40 50 60 70 80 90 100 Dc, Lc AND L/D CHARACTERISTIC CURVES AND SECTION ORDINATIS FOR THE GLBNN MARTIN 4 WlNO SECTION ! * r —•—. —-^ *• " '.5 5 10 ZO JO 40 50 60 TO 80 90 K» SECTION ORDINATES FOR THE GLENN MARTIN 5 WING SECTION 9
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