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• December 13, 2016 Create Date
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National Advisory Committee for Aeronautics, Technical Notes - Low Speed Investigation of a Thin, Faired, Double Wedge Airfoil Section with Nose Flaps of Various Chords

A thin, faired, double—wedge airfoil section was investigated with
plain nose flaps having chords equal to 12, 16, 20, and. 25 percent of the
airfoil chord. Section lift, drag, and. pitching—moment data were obtained
at S. Reynolds number of 5.8 million and. a Mach number of 0.17.

A greater positive shift in the angle of attack for zero lift and
more negative pitching moments resulted from increased chord of the nose
flap. Little effect of nose—flap chord on the maximum lift was found.
Increased chord of the nose flap produced the least drag at high lift
coefficients.

Although thin, sharp—edged airfoil sections offer considerable
promise for certain supersonic aircraft, the low minim lift and extreme
variation of drag with lift, characteristic of thin sections at low speeds;
have reduced the attractiveness of such sections for piloted aircraft.
Several low—speed investigations have indicated the benefit of nose flaps
in improving the minim lift and in reducing the drag at high lift coef—
ficients. Such benefits were shown in reference 1, wherein the results
obtained for a thin, faired, double-wedge airfoil with a l6—percent—chord
nose flap were presented.

Most of the low-speed investigations of sharp-edged airfoils that
have been undertaken to date have been primarily concerned with one
combination of airfoil and nose flap; consequently, there are available
few systematic results from which the effects of variation of the nose—
flap chord can be assessed. For this reason, it was thought desirable
to extend the investigation reported in reference 1 to include variation
of nose—flap chord. In this report, the force and moment characteristics
of the faired, double—wedge airfoil with 12-, 16—, 20—, and 25—percent—
chord nose flaps are presented. The investigation was conducted in the
Amos 7— by lO—foot wind tunnel No. 1.