E205

• E205A-PT (Fig. 12.13)

• E205B-PT (Fig. 12.14)

The popularity of the E205 grew tremendously with the introduction of the Airtronics SAGITTA standard class sailplane. Since this time, the E205 has become one of the most favored RC soaring airfoils. The SAGITTA, which was designed to compete effectively in multi-task events as well as F3B competition, owes much of its success to the E205. As compared with the E193, the better low-lift performance of the E205 offers improved wind penetration.

Of the two models constructed, the В version was the more accurate, es­pecially near the leading edge. Not surprisingly the drag of the В version is everywhere lower than the A.

From the polar it can be seen that the drag curves bunch at the lowest drag point near Ci of 0.25. Compare this to the AQUILA, where not only is the minimum drag at any Rn reached at a Ci of about 0.6, but it is also higher there than the E205 is at 0.25. Because the lift coefficient of a RC sailplane is about 0.2 when flying at high-speed cruise, the E205 is clearly better here than the AQUILA. This illustrates the general rule that good multi-task airfoils have the low drag region shifted to lower C;5s than thermal soaring airfoils.

Also see: S3021, RG15, E374, E193, SD5060, DF101, SD7080, SD7084 Digitizer plot: Figs. 10.7, 10.8 Airfoil comparision plot: Fig. 11.12 Polar plot: Figs. 12.13, 12.14

Lift plot: Fig. 12.15 .

Aircraft polar: Fig. 5.9

Thickness: 10.48% Camber: 3.01%