A new high-lift airfoil design philosophy has been developed and exper
imentally validated through wind-tunnel tests. A key element of the hi
gh-lift design philosophy was to make use of a concave pressure recove
ry with aft loading, Three codes for airfoil design and analysis (PROF
OIL, the Eppler code, and lSES) were used to design the example S1223
high-lift airfoil for a Reynolds number of 2 x 10(5). In wind-tunnel t
ests, the new airfoil yielded a maximum lift coefficient of 3.2. With
vortex generators and a 1% chord Gurney nap (used separately), the C-l
,C-max increased to 2.3. The airfoil demonstrates the rather dramatic
gains in C-l/max over those airfoils previously used for high-lift low
Reynolds number applications.