• S3021A-PT (Fig. 12.90)

• S3021B-PT (Fig. 12.92)

The S3021 has a bubble ramp longer than the transition ramp on the E205, and the resulting reduction in drag is dramatic. Certainly some of the reduction is because the S3021 is thinner than the E205, but, from the shape of the airplane polar shown in Fig. 5.9, it is clear that most of the drag reduction comes from better management of the laminar separation bubble.

Two models of the S3021 were built; version A is the more accurate one. Version В has a reflexed trailing edge which produces a steeper pressure recovery on the upper surface—a change which leads to a higher bubble drag.

Fig. 4.4 compares the data from the S3021A-PT and the E2Q5B-PT (Figs. 12.90 and 12.14 respectively) and shows that the drag of the S3021A-PT is almost everywhere lower than that of the E205B-PT. The ISES code predicted a similar drag reduction when it was used to compare the nominal airfoils.

Also see: E205, S3014, S3010, SD7080, SD7084

Digitizer plots: Fig. 10.33, 10.34

Airfoil comparision plot: Fig. 11.9

Polar plot: Figs. 12.90, 12.92

Lift plot: Fig, 12.91

Aircraft polar: Fig. 5.9

Thickness: 9.47% Camber: 2.96%

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