Hi Jim:

My Ultra Viper has no such change in the leading edge line. As Craig pointed out BVM used to offer an attachment for the leading edge called "droops" that were supposed to enhance the stall characteristics of the wing.

Presumably on the Viper they caused the outer portion of the wing to have a steeper angle of attach than the inner portion. That way the outer portion of the wing would stall and stop producing lift while the inner portion would continue to produce lift and retain control authority. Just thinking out loud for a second, it's hard to believe that the Viper would benefit from these devices since the AOA with flaperons in the landing configuration must be steeper than the outer wing even with the droops, but I don't know for sure and would certainly defer to an aerodynamic engineer for the last word. As I think through the alternative, it may make more sense for the outer portion of the wing to "keep flying" while the root alternates between stall and producing lift. This would allow the flaperons to continue to function for roll control.

Anyhow, that's my long winded way of saying that the droops were intended to improve stall characteristics.

Antony