Does anyone know of any designs for or examples of retractable leading edge slats added externally to an existing wing? In other words, the slat would form an external "cuff" changing the wing profile but would expose the original airfoil when deployed? The logic here is that I am looking at ways to make high lift devices like slats, slots and flaps optional--in other words, variations on the same design with and without high lift devices with little or no structural change to the basic design for maximum commonality between the different versions. Cheers, Matthew