The goal of this first work by Michael Selig (and his co-authors John Donovan and the late David Fraser) was to design a new group of high performance airfoils for radio controlled sailplanes. In this publication a large number of existing and newly designed airfoils are tested over a wide range of configurations and conditions. The performance of each airfoil is discussed in detail. Emphasis is placed on highlighting the important characteristics with respect to the other airfoils. Following these comments, smaller sections discuss:
(1) stall behavior
(2) trips and surface roughness
(3) trailing edge thickness
(4) surface waviness and contour accuracy.
Some of the airfoil discussions provide examples of sailplane performance in order to compare one airfoil with another. It should be noted in these examples that while one airfoil may be good for a particular configuration, it does not necessarily follow that it is good for all configurations. This is one of the reasons why there are so many "favorite" airfoils. In light of this, the reader is left to make the final decision as to which airfoil is best suited for a particular sailplane. To this end, a computer and an accurate performance prediction program are invaluable aids in the airfoil/aircraft integration process.
Even though most of the discussions are related to the RC sailplane, the airfoils are by no means restricted to this use. Furthermore, the aerodynamic phenomena described are common to all airfoils operating at low Reynolds numbers
Many of the airfoils tested were not originally intended for use on RC sailplanes, but have come to be used for this application by trial and error. On the other hand, the new SD-airfoils (as well as the DF-series) were designed for the RC sailplane. Rather than tailor a design to one, particular aircraft, the SD-series airfoils were designed for different, general classes of flying; for example, thermal-duration, F3B, multi-task, etc. Additional improvements in performance can probably be made by properly integrating the initial airfoil design process into the overall aircraft design.
Airfoil test results included in this book
Note: Airfoil images are not available for this volume
