SELIG AND DONOVAN AIRFOILS (SD)

A discussion of the design philosophy used behind the SD designs is given in Chapter 4.

SD2030

• SD2030-PT (Fig. 12.104)

The SD2030 was designed for operation at speeds higher than those typically found on most RC sailplanes. For this reason it is suitable for high-wing-loading F3B and F3E type aircraft. Since the lift range is narrow, camber-changing flaps are recommended.

Also see: SD2083, S2055, RG15, S3021

Digitizer plot: Fig. 10.39

Polar plot: Fig. 12.104 ‘

Lift plot: Fig. 12.105

Thickness: 8.56% Camber: 2.25%

SD2083

• SD2083-PT (Fig. 12.106)

The SD2083 was an early and not very successful attempt at an F3B design. The airfoil suffers from a fairly large separation bubble, and there is too much camber (2.85%) for good, high-speed performance.

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

Digitizer plot: Fig. 10.40

Polar plot: Fig. 12.106

Thickness: 8.96% Camber: 2.85%

SD5060

• SD5060-PT (Fig. 12.107)

For operation at Rn’s from 100k down (e. g. hand-launch RC sailplanes) the SD5060 is an improvement over the S3021. The stall characteristics of the SD5060, however, are not as benign as the S3021. In fact the airfoil stalls abruptly, much like the NACA 2.5411.

Also see: S3021, DF101, CLARK-Y Digitizer plot: Fig. 10.41 Polar plot: Fig. 12.107 Lift plot: Fig. 12.108

Thickness: 9.45% Camber: 2.30%