Leading-edge cuff

A leading-edge cuff is a fixed aerodynamic wing device employed on fixed-wing aircraft to improve the stall and spin characteristics.

A 1979 NASA report [9] explains that at high angles of attack the cuff discontinuity generates a vortex that acts as a fence, preventing the separated flow from progressing outboard.

The sharp discontinuity of the cuff is a key factor; all attempts by gradual fairing to suppress the vortex and the positive effects of the modification reintroduced an abrupt tip stall.

"[15] The most successful NASA experimental results were obtained on a quite low 6:1 aspect ratio wing (Grumman Yankee AA-1), with a DLE placed at 57% of the semi-span.

As the vortices (inboard cuff and wing tip) are efficient on a limited span length (about 1.5 times the local chord), a DLE alone is unable to preserve enough outboard lift to keep the roll control in case of high aspect ratio wing.

In the case of the high aspect ratio Cessna 210 wing (AR =11:1), roll damping at stall was not as efficient.

Full scale testing of a modified Cessna 172 showed that the outboard leading-edge cuff alone was not sufficient to prevent a spin departure, the aircraft lacking directional stability at high angles of attack.

[32][33] Several after-market suppliers of STOL kits make use of leading-edge cuffs, in some cases in conjunction with such other aerodynamic devices as wing fences and drooping ailerons.