Stepped Wing
Participants: Derrick Yeo, Ayden SongProject Affialiate and Sponsor:
Synopsis
In 1985 two artists published a book entitled "The Ultimate Paper Plane" in which they introduced the concept of a stepped airfoil.
A Kline-Fogelman airfoil configuration such as this was reported to have vastly improved the performance of their paper creations and was expected to have a similar effect on real aircraft. Stepped airfoils were claimed to possess excellent near-stall properties and being capable of "utilizing drag" to achieve improved aerodynamic efficiency.
Unfortunately, this latter claim is analogous to propelling your boat by sitting behind its sail and blowing on it; it requires energy to appear from nowhere. However, we feel that the re-circulating flow above a stepped airfoil may indeed have positive effects on airfoil characteristics at higher angles of attack.
As such, our study aims to investigate the near-stall behavior of a stepped airfoil configuration* in a flight situation and to assess how severe the reduction in aerodynamic performance is.
Our goals are to conduct flight tests with a suitably configured RC test platform based on a RC model airplane. These test results will then aid us in developing suitable FLUENT simulation cases that can reliably model the flow around a stepped airfoil.
To date, we have configured our selected RC airplane to acquire and record the necessary pressure data for airfoil testing. We are in the process of preliminary flight testing to finalize our pressure sensor configuration and are developing a basic 2-d model in FLUENT.
* A similar NASA sponsored study on the Kline Fogelman airfoil was carried out in 1974 at the University of Tennessee. However, the cross section carefully examined in the study had a wedge-like geometry lifted directly from the patent and kind of missed the point.
Additional Images
Project picture from (permission pending): http://users.acsol.net/~nmasters/vortex-lift/step_files/kfwing.gif
