Scale-effect tests in a turbulent tunnel of the NACA 65(sub 3)-418, a = 1.0 airfoil section with 0.20-airfoil-chord split flap Page: 4 of 22
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NACA ACR No. I4122
The pi tching-momert-coefficient slope with flap
deflected was erratic, but the pitching-moment-coefficient
elope for the plain airfoil became slightly more negative
with increasing Reynolds number.
I NTRODUC TI ON
Scale effect on low-dreg airfoils has regularly been
determined at Reynolds numbers above 3.0 x 10 in the
NACA two-dimensional low-turbulence pressure tunnel
(designated TDT). Tests were recently made in the TDT,
in the NACA two-dimensional low-turbulence tunnel, and
in the LMAL 7- by 10-foot tunnel to determine scale and
turbulence effects on the lift and drag characteristics
of a typical low-drag airfoil section over a wide range
of Reynolds number (reference 1).
The object of the present investigation was to find
the effect of Reynolds number on the aerodynamic
characteristics of a typical low-drag flapped airfoil
section tested under conditions of relatively high stream
turbulence. The NACA 65 -l8, a = 1.0 airfoil section
equipped with a split fl;p having a chord 20 percent of
the airfoil chord (0.20c) was tested in the LMAL 7- by
10-foot tunn 1 over a range of Reynolds number from 0.19
to 2.99 x 10
MODELS AND TESTS
Two models of 7-foot span with chords of 1 foot and
h feet were tested. Both models were built of laminated
wood 'with suitable steel reinforcemrrnts and were shaped
to the NACA 653-.18 profile. Ordinates for this section
were derived by the methods of reference 2 and are given
in table I. Both models were carefully finished and
were polished just before testing.
A 0.20c split flap was tested on each model. The
flaps were made of sheet steel and were formed to the
The airfoil section with thec flap is shown in figure 1.
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Tucker, Warren A. & Wallace, Arthur R. Scale-effect tests in a turbulent tunnel of the NACA 65(sub 3)-418, a = 1.0 airfoil section with 0.20-airfoil-chord split flap, report, September 1944; (digital.library.unt.edu/ark:/67531/metadc61404/m1/4/: accessed July 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.