• SD6080-PT (Fig. 12.113)

The SD6080 is an improvement over the S4061. Although the high-lift char­acteristics of the two airfoils are much alike, the SD6080 offers improvements at the low-lift end of the flight envelope.

Figures 12.94 and 12.113 show that the lower part of the SD6080 polar is extended over that of the S4061. Besides this extension, the drag over most of the polar is lower, particularly in those areas which are used by a typical RC sailplane.

• SD6080-PT u. s.t. xjc = 10%,k/c — .17%, w/c = 1.0% (Fig. 12.114)

• SD6080-PT u. s.t. xjc — 20%,k/c — .17%,wfc = 1.0% (Fig. 12.115)

• SD6080-PT u. s.t. x(c = 30%,hfc = .17%, ш/с = 1.0% (Fig. 12.116)

As shown in Figs. 12.114—12.116, trips were placed on the SD6080 at 10%,

20%, and 30% chord. Of the three cases, the trip at 30% is the best between Rn’s of 100k and 300k. As expected, the trip farthest forward is best at lower Rn’s. When the polars for the 30% trip and the untripped case are compared (Figs. 12.113 and 12.116), a 30% trip should clearly be used for Rn at and below 150k.

• SD6080-PT thickened trailing edge (Fig. 12.117)

As observed with the DAE51 and E374, the thickened trailing edge increases the overall drag on the order of 5%. It should be noted that the “thickened trailing edge* was slightly different for each of the three airfoils, but the effect of increased drag is common to all. The shape of the trailing edge is shown in Fig. 5.3.

Also see: S4061, E387, SD7037, SD7032 Digitizer plot: Fig. 10.43 Polar plot: Figs. 12.113-12.117 Thickness: 9.18% Camber: 3.74%