S2048

• S2048-PT (Fig. 12.74)

• S2048-PT with trips (Fig. 12.75)

• S2048-PT misc. trips (Fig. 12.76)

The S2048 was originally presented at the 1985 MARCS Symposium held in Madison, Wisconsin and has been used on the Synergy F3B sailplanes that have represented the U. S. at the World F3B Championships held in recent years (1987 and 1989). The airfoil is a “redesigned” HQ2/9 with slightly longer bubble ramps on the upper and lower surfaces (i. e. more gradual pressure gradients). Because the performance improvement due to changing these ramps was expected to be small in any case, more accurate models than the ones we tested would be re­quired to detect and measure it. And even if it could be measured, actually realizing or maintaining that difference would be difficult. Nonetheless the pos­sibility of bettering existing F3B airfoil designs may still yield to investigation at another time.

The effects of trips on the upper and lower surfaces are shown in Fig. 12.75; results of miscellaneous trip locations are shown in Fig. 12.76. Although no attempt was made to systematically study the effects of trip location on this airfoil, it does seem that a slight improvement in high-speed performance can be obtained through the use of an upper-surface trip around 60-70% chord combined with a lower-surface trip near 60%. As with the RG15 and HQ2/9, trips nearer the leading edge can be expected to produce lower drag at lower i£n’s.

Also see: HQ2/9, RG15, S2055, SD8000, SD2030

Digitizer plot: Fig. 10.27

Airfoil comparision plot: Figs. 11.4, 11.7

Polar plot: Figs. 12.74-12.76

Lift plot: Fig. 12.77

Thickness: 8.63% Camber: 1.94%

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